From the President

Dear colleagues:

This has been an extremely active year for IFToMM and TMM-related activities. The number of technical meetings of all sorts, conferences, symposia, and the like, was literally overwhelming, which is a reason why it was impossible to attend all events for which we received invitations, and which we wished to attend. Fortunately, in coordination with our quite mobile Secretary-General, Prof. Tatu Leinonen, we could attend many of these events. A unique event that I attended was the International Conference on Mechanical Transmissions and Mechanisms, MTM '97, from July 1 to July 4, in Tianjin, People's Republic of China, organized by the local committee of TMM. Judging from the conference itself and the works presented there, this committee is among the most active ones on TMM. Prof. Ce Zhang's leadership and enthusiasm are to be acknowledged for the activity that this committee is displaying. Just a few days prior to MTM '97, I had the opportunity to attend RAAD '97, the International Workshop on Robotics in the Alps-Adria-Danube Region, which took place in Cassino, Italy, from June 26 to 28. Although RAAD '97 is not an IFToMM-sponsored meeting, it was well attended by IFToMM colleagues, with an impressive representation from Italy.

This year marked the celebration of the Seventh IFToMM International Symposium on Linkages and Computer-Aided Design Methods-SYROM'97. This symposium is held every four years in Bucharest, Romania, thanks to the effort and enthusiasm of the late Prof. Manolescu, its founding father. The symposium continues under the leadership of Prof. Iosif Tempea, current Chair of ARoTMM, the Romanian Committee of TMM. This year, the symposium took place in August 26-30. May I bring this event to the attention of the IFToMM community, for we would like to see more international participation in the coming symposia. In recent years, international participation has declined, with an unusually weak participation from North America. Currently, I am holding an intensive dialogue with Prof.\ Tempea in looking for ways and means to make this symposium more attractive for the international IFToMM community. Any suggestions from the community at large are quite welcome.

Attendance to RAAD '97 and MTM '97 was not easy. Just prior to these events I was attending (and directing) a two-week NATO Advanced Study Institute on Computational Methods in Mechanisms, near Varna, in Bulgaria. For those who are too young to remember, Varna was the venue, in 1965, of the First International Congress on TMM, what became later the World Congress on TMM. Currently, ASIs must have a Co-Director from what is called a Cooperation Partner (CP) country. Essentially, all countries of the now defunct Warsaw Pact are CP countries. Another feature of current ASIs is that 50% of participants must be from CP countries, which gave us the opportunity to have participants from local committees of TMM of Eastern Europe and Central Asia. A book with the invited lectures held at this ASI will be published soon by Springer-Verlag, as per the announcement in the section on books in this issue.

Furthermore, and in trying to comply with a self-imposed mandate of bringing back to IFToMM Latin American committees that have suspended their membership, and to attract new members from Latin America, I accepted an invitation to participate in the III Congreso Iberoamericano de Ingeniería Mecánica (Third Ibero-American Congress of Mechanical Engineering), which was held in Havana, from September 24 to 26. The trip to Havana was fruitful: The Cuban Committee on TMM is quite active and numerous, and eager to get back on board. By the same token, contacts were established with the Executive Council of the Federación Iberoamericana de Ingeniería Mecánica, the organization behind the Congreso, which seems to be the most natural access to Latin American countries. I am confident that soon we will have Cuba again as a member and that, with the aid of the Federación, our number of members from Latin America will grow.

Attendance to the meetings mentioned above gave me the opportunity to meet old acquaintances like Prof. Minkoff, a driving force of BulKToMM, the Bulgarian Committee on TMM, as well as Prof. Emilija Vetadzokoska, Secretary-General of the Macedonian National Committee of TMM. Likewise, I had the opportunity to meet some Chairs of local committees of TMM, namely, Prof. Ce Zhang, of Tianjin, People's Republic of China, Prof. Hong-Sen Yan, of Tainan, Taiwan, and Prof. Z. Zh. Baigunchekov, of Almaty, Kazakhstan.

On another business, I take the opportunity to thank all Chairs of PCs and TCs who served in the past four-year term and stepped down, for the effort and time devoted to IFToMM. PCs and TCs are the core of IFToMM, and the health of the Federation depends first and foremost on the health of its PCs and TCs. It is my great pleasure to welcome on board all new Chairs of PCs and TCs, including those who are continuing from the previous term. I wish them all a most fruitful four-year term.

During the correspondence with outgoing chairs, we found that some committees have decided to have a Deputy Chair, termed Vice-Chair or Secretary-General. Our By-Laws do not recognize other IFToMM Officer than the Chair--referred to as Chairman in a rather politically-incorrect fashion--which has prompted us to wonder if we need a second officer in each PC or TC. Herewith I am asking the community to send us their views on this matter at their earliest convenience, but on time for discussion at the 1998 meeting of the EC, in early July. In talking of political correctness, a discussion has been going on at EC meetings on the necessity to change the name of the TC Man-Machine Systems. Here we also need some feedback from our readership.

My initiative under the name TMM 21 continues. This year was devoted to the compilation of a mailing list of contact persons in local committees. All Chairs of these committees were asked to submit a name and the corresponding address of the contact person, and many already responded. We have now a list of 14 contact persons and a Steering Committee composed of: Prof. Joseph Davidson (USA); Prof. Yukio Hori (Japan); Prof. Adam Morecki (Poland); Prof. Cezary Rzymkowski (Poland); Prof. Kenneth Waldron (USA); and myself. The addresses of these individuals are included in an appended mailing list. May I remind our readers that the purpose of TMM 21 is to produce, by mid 1999, the year in which the mandate of the current EC comes to an end, a report on the health of TMM and our views on its evolution in the XXI Century. The report should include an account of the technical accomplishments recorded up to the year of the report, with special focus on the accomplishments of the century, as well as an identification of the problems that lie ahead. It is important to point out in this report how we see TMM contribute to the technological developments to come and to the solution of the overwhelming problems in front of us: overpopulation; famine; and environmental damage, to name but a few. In order to get this project started, I prepared a position paper under the title ``A fin-de-siècle view of TMM'', which I presented at MTM '97 in Tianjin, and that I distributed for discussion. This paper is now available in the Home Page of IFToMM:

I am herewith reminding our readers that any comments on this paper are most welcome.

On the issue of local committees' standing with regard to their annual subscription, it is my pleasure to report that progress has been made in some cases with chronic problems. Likewise, I received assurances that some committees that have faced recent financial problems that prevented them from paying their annual subscription are now seriously studying means of solving these problems. On a piece of bad news, a committee with a longstanding affiliation to IFToMM and a pristine record with regard to the payment of its annual subscription, has seen the financial support from its national ministry withdrawn, which prevented it from meeting its 1997 payment. We are planning to contact individuals of this committee to find ways of normalizing their IFToMM standing.

Last, but not least, may I wish you all the most delightful holiday season, as 1997 comes to an end, and all the best for the new year.

Jorge Angeles, IFToMM President


From the Editor

Dear IFToMM Friends:

Here we are to meet our annual deadline, with the 1997 edition of the Newsletter, in which we update you on events that happened and those to come in the near future. We also include views from individuals of the IFToMM community at large. In this issue, we include two entries around the TMM 21 initiative, one submitted by Prof. G. Boegelsack, TU Ilmenau, Germany, and the other by Prof. A. Bessonov, Mechanical Engineering Research Institute, Moscow. Professor Boegelsack's point of view is both objective with regard to the role of TMM in modern engineering and optimistic with regard to the future of TMM. Prof. Boegelsack kindly submitted his entry in two versions, the German version being printed out verbatim; the English version appears with some editorial work behind. Professor Bessonov's brief discussion has some points in common with Professor Boegelsack's, although Prof. Bessonov's entry stops short of advancing a personal view. We hope that these entries will keep the discussion on the issues raised by TMM 21 animated and, that with the viewpoints of the IFToMM community at large, we will be able to come up with specific recommendations on these issues by mid 1999.

One more entry that we received is from Prof. P. J. Zsombor-Murray, of McGill University (Montreal, Canada), currently on sabbatical at The Technical University of Graz, where he is trying to bridge the gap between geometers (a.k.a. geometricians) and engineers. Professor Zsombor-Murray kindly allowed us to reproduce the Editorial that he wrote for a recent issue of the Transactions of the Candian Society for Mechanical Engineering, a bilingual English-French archival periodical, of which he is the Editor. We thus received two versions of this editorial, that we are including here. In the same section, On the Move, we are including a note received from Dr. Evert Dijksman, Technical University of Eindhoven, NL.

Again, we ask our readership for entries to the Newsletter, which can be informative or subjective. News on books, journals, theses, and other technical materials are welcome. Based on the space available, we may not be able to publish all entries on these items in their entirety, for which we ask our contributors for their understanding. Please note that contributions are welcome in any of the four official languages of IFToMM. We will publish these items in the language of submission. With regard to the format of submission, please note that the Newsletter is edited in LaTeX. We ask our readership, therefore, to submit their entries as ASCII files, and to do so by electronic mail, rather than by disquette.

In the obituary section, we have an entry submitted by Prof. K. Luck, Technical University of Dresden, on Prof. J. Müller's life as a productive educator and professional of TMM. We are publishing verbatim this entry in the language of submission, German.

On the business of the editorship of the Newsletter, Prof. G. Stepan, Technical University of Budapest, has kindly accepted to give the editorship a try. Prof. Stepan has also accepted to chair the Permanent Commission on Conferences, on a provisory basis, while the role of this commission is studied, and possibly merged with the activities around the editing of the Newsletter. A proposal from Prof. Stepan on this matter is expected for discussion at the 31st Meeting of the Executive Council, scheduled for early July, 1998 in Paris.

Also note that we are updating you on the 10th World Congress on TMM, to be held in Oulu, Finland, on June 20-24, 1999. Please block these dates in your calendar, and get ready to attend! Jorge Angeles, Editor


From the Secretary-General

New Members

The 30th IFToMM Executive Council Meeting took place on June 7, 1997 in Paris, at Laboratoire de Robotique de Paris, Université de Paris VI, with Prof. J.-C. Guinot as host. Eleven members of the EC and one guest, Prof. Oleg V. Berestnev, of Minsk, Belarus attended the meeting. Based on the result of a postal ballot, the local committees of Armenia, (South) Korea, and Pakistan were admitted as new members of IFToMM. The EC welcomes the new members and looks forward to their active participation in IFToMM activities.

 

Nine New Chairs of IFToMM PCs and TCs

Nine new Chairs of IFToMM Permanent Commissions (PCs) and Technical Committees (TCs) were appointed for the four-year term starting on January 1, 1998. The new Chairs are

 

  • PC Standardization for Terminology: Dr. Theodor Ionescu, of Bucharest, Romania;
  • PC Education: Prof. Kenneth Waldron, of Columbus (Ohio), U.S.A.;
  • PC History of TMM: Prof. Marco Ceccarelli, of Cassino, Italy;
  • TC Computational Kinematics: Dr. Jean-Pierre Merlet, of Sophia-Antipolis, France;
  • TC Gearing: Prof. Veniamin Goldfarb, of Izhevsk, Russia,
  • TC Linkages and Cam Mechanisms: Dr. Miroslav Vaclavik, of Liberec, Czech Republic;
  • TC Robots and Manipulators: Prof. Jean-Claude Guinot, of Paris, France; and
  • TC Transportation Machinery: Prof. Bahram Ravani, of Davis (California), U.S.A.
Besides, the EC decided to establish a new TC for Reliability in TMM, based on the proposal of Prof. Oleg V. Berestnev. Prof. Berestnev, of Minsk, Belarus, was appointed Chair of this new TC. The Chairs of the PCs and TCs below were reappointed for a new four-year term:

 

  • PC Publications: Prof. Terry E. Shoup, of Santa Clara, California (USA);
  • TC Man-Machine Systems: Prof. Krzysztof Kedzior, of Warsaw, Poland;
  • TC Mechatronics: Prof. Manfred Hiller, of Duisburg, Germany;
  • TC Micromechanisms: Prof. Teru Hayashi, of Yokohama, Japan; and
  • TC Rotordynamics: Prof. Giorgio Diana, of Milan, Italy.
Furthermore, Prof. L. P## &#;'27 st's term as Chair of the TC Nonlinear Oscillations continues until the end of 1999. The affiliations and addresses of the foregoing IFToMM officers are included in the mailing lists appended to this issue.

The role of the PC Conferences, in light of the current communication scheme of IFToMM, based on the Newsletter, was discussed. In last year's EC meeting, Prof. Angeles suggested the establishment of the new position of Communications Officer within the EC, but without enlarging it. The idea was to replace one of the existing positions for this new one in due time, since this change requires a constitutional modification. In this light, Prof. Gabor Stepan, a member of the EC, was asked to study the issue and submit a proposal for the EC meeting of 1998, which will be held in Paris.

On the Road

This year I attended several conferences and symposia, where I have given technical papers and taken the opportunity to provide an account of the IFToMM activities, especially promoting the 10th World Congress on TMM, as per the item below. With these trips, I have been attempting to attract new members to IFToMM. Here is a list of my travel activities:

 

  • May 22-23, 1997: The OST-97 Symposium, in Tallinn, Estonia. The Finnish Committee of TMM was a sponsor of this symposium, with the participation of colleagues from Estonia, Finland, and Sweden. The organizers of the symposium were Professor Ilmar Kleis and Dr. Lembit Uksti from Tallinn TTU.
  • ICED`97 was held on August 19-21 at the Technical University of Tampere, Finland. The Finnish Committee of TMM was cosponsor of the symposium, chaired by Professor Asko Riitahuhta. During the symposium, the local Committee had its own meeting.
  • August 26-29: Syrom`97 was held in Bucharest, Romania, under the organization of ARoTMM, the Romanian Committee of TMM, with Prof. Iosif Tempea as Chairman.
  • September 2-4: ISMM`97 took place in Belgrad, Yugoslavia, with Prof. Todor L. Pantelic as Honorary Chairman, and Prof. Zivota Zivkovic as Chairman.
  • September 18-22: The 1997 ASME Design Technical Conferences were held in Irvine California, with Prof. Bahram Ravani, Davis, as Chairman. This was the biggest conference that I attended this year.

10th World Congress Update

The 10th World Congress on TMM will take place in Oulu, Finland, from June 20 to June 24, 1999. The important deadlines are listed below:


tabular28

For further updates, please consult the World Congress WWW Home Page:

Submitted by Prof. Tatu Leinonen
IFToMM Secretary-General

Note from the Editor

For everybody's benefit, we reproduce below a note from Vol. 5, if with some editorial changes in the wording, on the 10th World Congress:

``PCs and TCs were requested not to organize independent workshops or symposia in 1999, while including all in the 10th World Congress in 1999. The PCs and TCs will evaluate the full papers of their own symposia. The arrangements for paper reviews are as follows:

  1. Abstracts are sent by the authors to their local committees, which will conduct the first evaluation. Each local committee then will propose to which PC or TC the paper belongs.
  2. The Congress Chair will ask authors of accepted papers to submit their full paper in due time.
  3. The final evaluation, based on the full paper, will be conducted by the corresponding PC or TC.
  4. The Congress Chair will announce the result of the evaluation to each author.''

Notwithstanding the above policy, the EC granted its endorsement to the 4th World Congress on Gearing and Power Transmission, to be held in Paris, from June 1 to June 3, 1999, just 17 days before the 10th World Congress on TMM. Prof. Veniamin Goldfarb, appointed Chair of the TC Gearing, alerted the EC on this congress in 1999, and recommended that IFToMM give its endorsement to the congress. The EC accepted the reasons given by Prof. Goldfarb.


TMM 21

We include below two entries submitted in the framework of this initiative; the first one, by Prof. G. Boegelsack, of the Technical University of Ilmenau, received both in German, and English. The English version was edited. The paper referred to by the author, ``A Fin-de-Siècle View of TMM'', is available at the IFToMM Home Page

Moreover, the Newsletter entry by Prof. Davidson to which Prof. Boegelsack refers, is available in the same Home Page, within the 1996 issue of this Newsletter. The second entry was submitted by Prof. A. Bessonov, Russian Academy of Sciences, Moscow. This entry was submitted in English, and appears here in edited form.

Some Thoughts About the Prospect of Developments in Teaching and Research

The paper written by Prof. J. Angeles, ``A Fin-de-Siecle View of TMM'', within the context of the IFToMM initiative TMM 21, raised a welcome and broad discussion. First comments are on the table, e.g. by Prof. J. K. Davidson, in his entry under the title ``The Health of TMM'' [see the IFToMM Newsletter issue of 1996]. These comments encouraged me to summarize my opinion on the state of and possible progress in TMM:

 

  1. The technical evolution at present is characterized by the increasing automation of very different processes in all fields of human life. An essential feature of automation is information, which is represented by sequences of signals. Information needs carriers, which should have negligible inertia (e.g., electromagnetic and light waves).
  2. In information processes that are automated increasingly by means of electronic and optical principles, mechanics is mainly needed only in elements for operating, orienting, supporting, and enveloping. In contrast to that, automation of processes involving the transformation of material objects do need mechanics with all its complexity: geometry; kinematics; dynamics; control; and moving masses.
  3. Therefore, machines are invariably associated with the living conditions of mankind: Human beings are individuals who eat, live, dress, travel, etc. For that, they need goods that are to be produced, i.e., goods whose form, composition, and position have to be processed.
  4. Machines are engineering systems that supply mechanical power: Driving forces are to be generated (by means of motors and actuators), transmitted to the driven system (mechanism), and brought to effect a task (end-effector). Control elements influence the input energy or act on the power flow. Automatic control demands sensors and signal processing.
  5. Computer applications in motion systems make possible to simultaneously control a number of actuators. Complicated motions can be resolved into several components (axes). In this way, the structure of a system becomes simpler and can be synthesized out of modules. The dimensional synthesis of sophisticated mechanisms can be replaced by the synthesis of the control software. The same structure can now meet numerous different functions.
  6. Actuators in a motion system can be arranged either ``serially'', i.e., some of the actuators, laid out in an open chain, are moved themselves under the effect of their downstream counterparts, or ``in-parallel'', i.e., all actuators are frame-fixed, the transmission mechanisms needing to develop additional structural effort. There are many hybrid solutions between these extreme possibilities. The designer has to find the optimum solution.
  7. In the development and analysis of an automatic machine, the complexity of the respective system is to be considered. Mechanisms are to be treated as system elements in their interaction with actuating, effecting and controlling elements. Computers are unavoidable not only for the control of the power transmission but also for the simulation and analysis in the design process.
  8. Power transmission by mechanisms is determined by forces and motion. For a long time in the training of students in the theory of mechanisms, scaled models have been used in order to bring to life the sometimes rather complicated motions of spatial mechanisms. This goal is reachable much more extensively and effectively nowadays by means of computer simulations and animations during the lectures.
  9. The development of mechanism technology is often impacted by new demands for machines, instruments, devices, or by progress in other research fields. Recent significant examples are: Microprocessors made possible to control open and closed kinematic chains with a high degree of freedom; new materials and new processing technologies permit the development of mechanisms in extremely miniaturized dimensions --micromechanics, micromechanisms, and microelectromechanical systems (MEMS).
  10. Although motion systems in technology and biology have several common features, zoological structures still offer a host of design principles which are by far not yet investigated, let alone utilized. Biological motion systems can perform fast, slight, and precise motions. These systems exist in macro- and microscales and contain compliant elements; they should be taken increasingly more often as models in the pursuit of new engineering solutions.
  11. The ``classical'' theory of mechanisms mainly deals with rigid-body systems. Mechanisms having elastic elements usually are modelled as rigid structures with concentrated flexibilities. For compliant mechanisms having continously-distributed flexibilities and possibly nonuniform material properties (density, texture), those models are not valid. Although some succesful research has already been reported, e.g., by Crossley, Shoup, Midha, and others, additional efforts on the analysis and synthesis of these systems seem to be necessary.
  12. My recommendations for teaching the theory and practice of mechanisms would be:
  • to keep the research results of the classical theory of mechanisms and to consistently use computer methods for calculating and visualizing mechanisms (e.g., kinematic analysis and Burmester's theory);
  • to consider the generation, transmission, and control of motion and forces in motion systems in their full complexity;
  • to deal with multiactuator systems and the related control algorithms;
  • to introduce, in a step-by-step fashion, research results in new fields (e.g. compliant mechanisms, bionics);
  • to train students in team work and interdisciplinary work.
  • In the German language, the term ``Mechanismus'' is known to have a broader meaning and a more comprehensive scope than the term ``Getriebe'' (as in ``ungleichmäßig übersetzendes Getriebe'', i.e., nonuniform-transmission mechanisms), which it should overtake, rather than the other way around. This term should also include what is taugth in courses on ``transmission engineering'' in some departments of Mechanical Engineering, namely, gear trains, chain-and-sprockets, belt-pulleys, etc. ``Getriebe'' cannot include concepts as manipulators, pedipulators, biological motion systems, compliant mechanisms, and micromechanisms. Furthermore, the lonesome place of ``Getriebe'' in an international context is to be considered. A teaching experience of a few decades at the Technical University of Ilmenau has taught me that ``Mechanismentechnik'' (mechanism engineering) has a broader scope than ``Getriebetechnik'' or ``Getriebelehre'' among colleagues and students from elsewhere. Happily, IFToMM has implicitly given the term ``mechanism engineering'' a terminological legitimacy with the expression ``Theory of Machines and Mechanisms''.
  • Countering the proposal of replacing the term ``Getriebetechnik'' with ``Bewegungstechnik'' (motion engineering), we must take into account a few items, namely,
a)
``Motion'' implies a reduction to kinematics. The underlying forces are not apparent in this expression. ``Getriebetechnik'' would have to give up a certain part of its realm.

 

b)
Electrical, pneumatic, and hydraulic actuators are also motion generators, and hence, belong to ``motion engineering''.

 

c)
With regard to motion-oriented biomechanics and sports science there are bound to be clashes. The term ``mechanism engineering'' does not lead to these problems and finds itself more compatible with the internationally recognized ``TMM'' expression.

 

In Summary, I would like to say that there seems to be no reason to worry about the future of TMM. The foresight of the IFToMM founding fathers, nearly thirty years ago, is highly commendable. Since then, the number of IFToMM members grew significantly, the scope of IFToMM became broader and more differentiated. IFToMM became a world-wide recognized scholarly organization. IFToMM's technical journal, MMT, is highly regarded, while its congresses and symposia are well attended. IFToMM has played an important role in the development of TMM, a fallout of this positive effect not being noticeable. In the future, the technical evolution will continue to demand efficiently controllable and adaptive motion systems. That cannot be done without the theory of mechanisms, which will remain a cornerstone of mechanical engineering. However, different universities will answer the question of depth and breadth of the related training in a different way. Therefore, it is highly desirable that the IFToMM iniative TMM 21 lead to some practical recommendations.

Prof. Dr. G. Boegelsack, Technische Universität Ilmenau, Germany

Einige Gedanken zur Entwicklungs-Perspektive in Lehre und Forschung der TMM

Der Aufsatz von Prof. J. Angeles ``A Fin-de-Siecle View of TMM'' und die sich anschließende IFToMM-Initiative TMM 21 haben eine begrüßenswerte und fachweltweite Diskussion über die zu erwartende Entwicklung des Lehr- und Forschungsgebietes TMM ausgelöst. Erste Stellungnahmen z. B. von Prof. J. K. Davidson (``The Health of TMM'') [s. die 1996-Nummer des IFToMM-Rundschreibens] liegen vor. Sie haben mich dazu angeregt, meine Einschätzung der Situation und des potentiellen Fortschritts in den folgenden Thesen zusammenzufassen.

  1. Die technische Evolution der Gegenwart ist durch zunehmende Automatisierung von sehr unterschiedlichen Prozessen in allen Bereichen menschlichen Wirkens gekennzeichnet. Automatik (als Selbststeuerung) ist ausdrücklich informationsdeterminiert. Information, dargestellt durch eine Folge von Signalen, braucht Informationsträger, die im Interesse größter Effektivität möglichst trägheitsarm sein müssen (Elektromagnetische Wellen, Lichtwellen).
  2. Informationsprozesse werden zunehmend mit Hilfe elektronischer und optischer Wirkprinzipien automatisiert. Mechanik ist dabei nur für Bedienungs-, Richt-, Stütz- und Hüllfunktionen zuständig. Im Unterschied dazu erfordert die Automatisierung von Prozessen, in denen auf massebehaftete Objekte eingewirkt wird, zugleich auch Mechanisierung, d. h. die zweckgerichtete Verbindung von Geometrie, Kinematik, Dynamik, Steuerung und bewegter Masse in automatisierten Maschinen.
  3. Maschinen und Mechanismen sind demzufolge eng mit den Existenzbedingungen der Menschheit verkoppelt: Menschen sind Einzelwesen, die individuell essen, wohnen, sich kleiden und fortbewegen wollen. Die dafür notwendigen Gegenstände und Mittel sind massebehaftete Objekte, die bestimmten Stoff-, Form- oder Lageänderungen im weitesten Sinne zu unterziehen sind, also maschinelle Arbeitsprozesse mit einer großen Menge von Einzelobjekten und meist intermittierender Charakteristik erfordern.
  4. Maschinen sind technische Systeme, die mechanische Leistung vollbringen: Bewegende Kräfte werden erzeugt (Motor, Aktuator), zur Wirkstelle übertragen (Mechanismus als Transformator) und zur Wirkung gebracht (Effektor). Die Steuerung nimmt zumeist Einfluß auf die Antriebsenergie oder wird an anderen Stellen im Leistungsfluß wirksam. Automatische Steuerung (Regelung) erfordert Sensorik und Signalverarbeitung.
  5. Die Anwendung der Computertechnik zur Bewegungssteuerung erlaubt, komplizierte Bewegungsvorgänge, zerlegt in einzelne Komponenten, multi-axial simultan zu steuern. Der strukturelle Aufbau wird dadurch einfacher und modularisierbar, an die Stelle der ``Maß-Synthese'' von Hardware tritt die Entwicklung von Steuer-Software. Mit gleicher mechanischer Struktur können unter einfacher Änderung des Steuerpro
    gramms unterschiedliche Funktionen realisiert werden.
  6. In einem Bewegungssystem können dezentralisierte Antriebselemente in bezug auf das Gestell ``seriell'' angeordnet sein, das heißt, einige Aktuatoren sind in den offenen Antriebsketten unter bestimmten dynamischen Nebenwirkungen mitzubewegen, oder ``parallel'', das heißt, die Aktuatoren sind gestellfest, und es ist ein grösserer struktureller Aufwand für die Übertragungsmechanismen erforderlich. Zwischen beiden Extremen sind viele Hybridlösungen möglich, deren strukturell-dynamisches Optimum durch geeignete Verfahren zu bestimmen ist.
  7. Die Entwicklung automatisierter Maschinen und die Analyse ihres Betriebsverhaltens verlangen eine Arbeitsmethodik, die die Komplexität des jeweiligen Systems berücksichtigt. Mechanismen jeglicher Art sind als Systembestandteile in ihrem Zusammenwirken mit den Antriebs-, Steuer- und Wirkelementen zu behandeln. Die Computertechnik ist dabei von wesentlicher Bedeutung sowohl für die automatische Steuerung des Leistungsübertragungsprozesses als auch für dessen Analyse und Simulation.
  8. Die Leistungsübertragung durch Mechanismen wird bestimmt von Kraftwirkungen und den damit einhergehenden Bewegungen. In der Ausbildung zur Mechanismentechnik (Getriebelehre) werden seit jeher Modelle benutzt, um die oft sehr komplizierten Bewegungen von Mechanismengliedern in der Ebene und im Raum bzw. auch andere geometrische Zusammenhänge (zum Beispiel Lagengeometrie, Bahnkurven, Achsenflächen, belastungsabhängige Deformationen) anschaulich werden zu lassen. Dieses Ziel läßt sich mit Hilfe von Computer-Simulationen (im Hörsaal und im Seminarraum) weit umfassender, effektiver und rationeller erreichen.
  9. Die Mechanismentechnik empfängt Impulse für ihre Weiterentwicklung aus neuen technologischen Anforderungen an Maschinen, Geräte, Instrumente und nutzt auch technische Fortschritte anderer Fachgebiete. Als markante Beispiele können gelten: Mikroprozessortechnik ermöglicht die Anwendung offener und geschlossener kinematischer Ketten hohen Freiheitsgrades in der Robotertechnik; neue Werkstoffe und neue Fertigungsverfahren erlauben die Entwicklung nachgiebiger Mechanismen (compliant mechanisms) bis zu Strukturen mit in sich geschlossener Stoffkohärenz und in extrem miniaturisierten Dimensionen (Mikromechanismen, Mikromechanik, Mikroelektromechanischen Systemen, als MEMS abgekürtzt).
  10. Technische Bewegungssysteme haben viele Merkmale mit biologischen Bewegungssystemen gemeinsam. Die unübersehbare Vielfalt zoologischer Bewegungsstrukturen bietet eine Fülle von Arbeitsprinzipien, die aus konstruktiver Sicht noch nicht hinrechend erforscht sind, geschweige denn in technischen Systemen genutzt werden. Biologische Bewegungssysteme erlauben meist sehr schnelle, geschmeidige und präzise Bewegungen. Sie treten in Makro- und Mikro-Dimensionen auf und haben nachgiebige Strukturelemente. Sie sollten mehr noch als bisher nach möglichen Vorbildern für neue oder verbesserte, innovationsträchtige technische Lösungen durchforscht werden.
  11. In der ``klassischen'' Mechanismentechnik steht bisher überwiegend der Sonderfall der Starrkörper-Strukturen im Vordergrund, Mechanismen mit elastischen Elementen werden als ``gefederte'' Strukturen mit konzentrierten Elastizitäten modelliert. Das reicht für den allgemeinen Fall der nachgiebigen Mechanismen mit verteilten Elastizitäten und möglicherweise differenzierten Materialeigenschaften (Dichte, Textur) nicht mehr aus. Für die Analyse und Synthese dieser beweglichen mechanischen Kontinua ist ebenfalls noch viel Forschungsarbeit zu leisten.
  12. Kurzgefaßt lassen sich einige Aufgaben für die Lehre in der Mechanismentechnik folgendermaßen beschreiben:
    • Beibehaltung der wissenschaftlichen Erkenntnisse der ``klassischen'' Mechanismentechnik und konsequente Anwendung der Computertechnik für Berechnung und Veranschaulichung (Z.B. kinematische Analyse, Burmester-
      Theorie u.a.);
    • Komplexe Betrachtung von Erzeugung, Übertragung und automatischer Steuerung von Bewegungen und Kräften in Bewegungssystemen;
    • Behandlung von Multi-Aktuator-Systemen und deren Steuerungsalgorithmen;
    • Schrittweise Einbeziehung von neuen Forschungsergebnissen (Z. B. Nachgiebige Mechanismen, bionische Bewegungssysteme);
    • Training der Studenten in Team-Arbeit und interdisziplinärer Arbeit.
  13. Im deutschen Sprachgebrauch sollte dem Begriff ``Mechanismus'' mehr Bedeutung und ein umfassenderer Begriffsinhalt zugemessen werden. Er sollte dem Begriff ``Getriebe'' übergeordnet und nicht (als ``ungleichmäßig übersetzendes Getriebe'') untergeordnet sein. Er sollte auch die an einigen deutschen Maschinenbau-Fakultäten unter ``Antriebstechnik'' behandelten Getriebe wie Zahnradgetriebe, Kettengetriebe, Bandgetriebe usw. eins-
    chließen. Es fällt schwer, im Zusammenhang mit Manipulatoren, Pedipulatoren, biologischen Bewegungssystemen, nachgiebigen Mechanismen, Mikromechanismen von ``Getrieben'' zu sprechen. Dazu kommt die solitäre Stellung der Bezeichnung ``Getriebe'' im internationalen Terminologie-Vergleich. Jahrzehntelange Lehr-Erfahrungen an der TU Ilmenau haben mir auch gezeigt, daß ``Mechanismentechnik'' sowohl bei Fachkollegen anderer Wissenschaftsgebiete wie auch bei Studenten mehr Verständnis findet als ``Getriebetechnik'' oder ``Getriebelehre''. Erfreulicherweise gibt die IFToMM mit dem Begriff ``Theorie der Maschinen und Mechanismen'' dafür eine terminologische Legitimation.
  14. Gegen den Vorschlag, anstelle von ``Getriebetechnik'' die Bezeichnung ``Bewegungstechnik'' einzuführen, sind folgende Bedenken anzumelden:
    a)
    ``Bewegung'' impliziert eine Einschränkung auf die Kinematik. Die zur Leistungsübertragung notwendigen Kraftwirkungen werden in der Bezeichnung nicht sichtbar. Die Getriebetechnik würde möglicherweise einen gewissen Teil ihres bisherigen Terrains preisgeben.
    b)
    Die Elektrische Antriebstechnik (``Antrieb'' im Sinne von ``Energiewandler''!), die Pneumatik und die Hydraulik erzeugen mit Aktuatoren jeglicher Art natürlich auch Bewegung, sie betreiben ebenfalls ``Bewegungstechnik''.
    c)
    Auch im Hinblick auf bewegungsorientierte Biomechanik und die Sportwissenschaften würden Irritationen unvermeidbar sein. Die Benennung ``Mechanismentechnik'' führt nicht zu diesen Problemen und befindet sich zudem in besser Übereinstimmung mit der international eingeführten und anerkannten ``TMM''.

Als Schlußfolgerung ist festzustellen, daß eine Sorge um die Zukunft des Lehr- und Forschungskomplexes TMM nicht begründet ist. Es war weit vorausschauend und eine sehr verdienstvolle Leistung der Gründer der IFToMM, diese Föderation vor nunmehr fast dreißig Jahren ins Leben zu rufen. Seither ist nicht nur ihre Mitgliederzahl deutlich gestiegen, sondern auch ihr Arbeitsbereich hat sich ständig erweitert und differenziert. Sie hat sich zu einer anerkannten Fachorganisation entwickelt, die auch für benachbarte Fachgebiete eine bemerkenswerte Attraktivität hat. Das wissenschaftliche Journal MMT zeichnet sich durch ein hohes fachliches Niveau aus. Das gleiche gilt für die sehr frequentierten Weltkongresse und Symposien. Die IFToMM hat die weltweite Entwicklung der TMM maßgeblich gefördert, es ist kein Nachlassen dieser positiven Wirkung erkennbar.

Die technische Evolution wird auch weiterhin immer leistungsfähigere steuerbare und adaptive Bewegungssysteme verlangen. Die Grundlagen der Mechanismentechnik werden unverzichtbarer Bestandteil der Ausbildung von Maschinenbau-Ingenieuren bleiben müssen. Die Frage nach der Lehrintensität und -extensität dieses Faches und der institutionellen Zuordnung der Fachvertreter wird allerdings in den einzelnen Technischen Universitäten unter
schiedlich beantwortet werden. Es wäre deshalb zu begrüßen, wenn aus der IFToMM-Initiative TMM 21 international abgestimmte Empfehlungen abgeleitet werden könnten!

Prof. Dr. G. Boegelsack
Technische Universität Ilmenau,
Deutschland Current mechanization and automation of human activities have been developing intensely in many branches of engineering.

Our Federation cannot be an outsider in this matter and should accept all modern scientific achievements connected with the process of automation and mechanization. I think that IFToMM has recently been introducing essential changes in the structure and formation of new technical committees and sections at IFToMM Congresses. This process should be continued.

Modern requirements of research institutes, industry, and universities must be taken into account in developing our Federation. Does the name of our Federation correspond to these modern requirements?

Current and prospective machines and mechanisms should be intelligent systems with a maximum of automation and computer control, highly productive, energy-efficient, reliable, ecologically-friendly, with low metal contents, and meet other requirements.

No discipline can embrace all the complexity of these issues including TMM. Researchers and designers use achievements of many disciplines when designing modern machines, which is just natural.

Submitted by Professor A. P. Bessonov
Russian Academy of Sciences, Moscow

Further Reading

The reader is invited to look at ``Motion Control in Product Design'', by A. G. Erdman, University of Minnesota, published in the August, 1997 issue (Vol. 119, No. 8) of Mechanical Engineering, the monthly publication of ASME International.

Moreover, the difference between ``Mechanismus'' and ``Getriebe'' in German is described in the Vol. 6, No. 5 (1991) issue of Mechanism and Machine Theory devoted to terminology, and compiled by the IFToMM Commission A on Standards for Terminology.


What's in a Name?

In the 1996 issue of this Newsletter the IFToMM President, Jorge Angeles, asked ``whether Theory of Machines and Mechanisms is a suitable name for our organization''. This question was discussed at the EC meeting, the agreement reached being to keep the abbreviation IFToMM unchanged and to change only the name behind it. Based on the proposals discussed, the new meaning of IFToMM would be one of the names below: {

International Federation for the

 

  1. Theory of Machines and Mechatronics;
  2. Theory of Machines and Mechanical Systems;
  3. Technology of Machines and Mechanisms;
  4. Technology of Machines and Mechatronics; or
  5. Technology of Machines and Mechanical Systems.
The EC decided to ask all member committees for their opinion and submit a proposal prior to the next EC meeting, to be held in early July, 1998. Submitted by Prof. Tatu Leionen
IFToMM Secretary-General It is not clear from its name that IFToMM has developed both in breadth and depth. In fact, we are currently introducing changes in the content of our TCs.

Other similar international organizations like IFAC, IUTAM, etc. also introduce current research achievements, without changing their names.

We are ready to discuss many problems within IFToMM but the matter of a name change is not simple, and should be given careful consideration. VARIANT 1 It is almost impossible to include in the very name everything we even partially use in our work. Nevertheless, we can try to emphasize that the Federation understands and takes into consideration the present. For instance, the following names are to be discussed.

  • IFATMM - International Federation for Advanced Theory of Modern Machines
  • IFATPM - International Federation for Advanced Theory and Practice of of Machines

The reading in abbreviation: IFAT MM, IFAT PM.

However, we must not forget euphony!

I am ready to discuss any other names and principal matters within TMM 21. One should be very careful including in the name such words as mechanics, electronics, control, automatics, in order to avoid confusion with other International organizations like IUTAM, IFAC, etc. VARIANT 2 It is necessary, perhaps, to leave the principal name as is, but under the name, an explanation would be given in brackets, in small print, e. g., INTERNATIONAL FEDERATION FOR THE THEORY OF MACHINES AND MECHANISMS: Advanced Theory, High Technology of Design and Control, Modern Applications. I am in a position to discuss other suggestions. This is just a summary of my opinion.

Submitted by Professor A. P. Bessonov
Russian Academy of Sciences, Moscow Consider the name:

International Federation for Theory and Advancement of Mechanical Systems, with the accronym IFTAMS.

Maybe Theory could be replaced by a derivative of Technology, or something else.

Submitted by Dr. Farzam Ranjbaran,
Bombardier Inc., Mirabel, Quebec, Canada


On the Move

News from Austria

Here I am in sunny Styria in the fall, beginning a sabbatical year in the Geometry Institute of the Technical University of Graz, with the Mechanics Institute one floor down. An ideal situation, you say, and so I thought and so it may still come to pass. However it's going to be hard to bridge the chasm between geometry and mechanical engineering. Here's an example. A dear colleague at McGill regularly laments the geometricians' tendency to seek an ``ideal coordinate system'' in which to set up problems. Well, that's what engineering is all about; formulating problem models and trying to solve them, but the more general the better; so, special coordinate systems are out, OK?

After catching the last day (Austrians are inveterate procrastinators, just like me; of course there was a crowd) of an exhibition (It packs up and moves to Museum of Modern Art in New York) of some works of Egon Schiele, last Sunday, a friend and I tried to get an algorithm to obtain the lines which intersect four given ones in space. This relates to simple screw systems as these pertain to kinematics and statics, so you can see the engineering motive. Essentially this comes out as four or five linear equations and a quadratic one and all looked easy until MAPLE said ``object too large''. After a few beers and head-scratching (The late Paul Erdos said a mathematician is a device for turning coffee into theorems. Geometers, at least Austrian ones, and engineers share affinity to other lubricants), one line was put on the z-axis, another intersecting and perpendicular to the x-axis. A little high-school algebra and a fewer-than-twenty-statement algorithm finished the job. Score one for geometry! Not entirely, the simplification requires coordinate transformations to and from the idealized frame and this is exactly what my engineer friend deplores in the name of coordinate-freedom.

In this case it was worthwhile because the alternative frustration would entice any engineer to sacrifice a bit of dedication to pure generality in exchange for results. On the other hand, one may carry things a bit too far. A second geometrician comes along, ``Hah!'' saith he, ``I can do better and use a special projection that will render three of the four lines along each of the mutually perpendicular axes.'' Of course, then things are even simpler but the poor guy gave up trying to obtain the transformations to and from his wonderfully trivial kernel. It all boils down to your work will reflect how you feel, what you're familiar with, who you talked to last and how far you're prepared to go to prove your way is best.

Auf Wiedersehen!, it's off to swinging Budapest and away from all this arcane stuff for a bit.

Submitted by Prof. Paul J. Zsombor-Murray, McGill University, on sabbatical at TU Graz. This entry first appeared as the Editorial of Vol. 21, No. 3, 1997 issue of the Transactions of the Canadian Society for Mechanical Engineering.

 

News from the Netherlands

Dr. Evert Dijksman, TU Eindhoven, sent us a post card with an extensive account of his fall trip throughout many places in North America. Dr. Dijksman is in his first year of retirement, and before he has recovered from such a hectic trip, he is already wondering what to do next. In that trip, Dr. Dikjsman visited the University of Florida at Gainsville, then McGill University, in Montreal, followed by a visit to the General Motors R & D Center, near Detroit, with a short stop at Toronto. He then went on to Cookeville, TN and Auburn, AL, before returning to the Netherlands. Dr. Dikjsman and his wife, Maty, drove a total of 8,000 km, through 16 states and provinces in a matter of only a couple of weeks.


Ça bouge

Des nouvelles d'Autriche

En ce moment j'ai la chance d'être en Styrie, sous le soleil autrichien, depuis l'automne, dans le cadre d'une année sabbatique au département de Géométrie de l'Université Technique de Graz. L'Institut de Mécanique se trouve un étage plus bas. Situation idéale diriez-vous et vous auriez raison ; cela est peut-être le cas. Il est de plus en plus difficile de combler le gouffre entre la géomètrie et le génie mécanique. En voici un exemple : Un de mes collègues de McGill se lamente régulièrement sur la tendance des géomètres à chercher un ``système de coordonnées idéal'' qui permettrait de résoudre les problèmes. C'est le propre de tout ingénieur de modéliser des problèmes et d'essayer de les résoudre. Mais plus c'est général, mieux c'est, ce qui exclut les systèmes de coordonnées spécifiques, n'est-ce pas?

Après avoir assisté le dernier jour à une exposition d'Egon Schiele (elle part pour le Musée d'Art Moderne à New York), où il y avait beaucoup de monde (les Autrichiens s'y prennent toujours au dernier moment, comme moi), un ami et moi avons essayé de concevoir un algorithme pour trouver les lignes qui coupent quatre autres lignes données dans l'espace. Ceci est relié à des systèmes simples hélicoidaux, comme ceux qui appartiennent à la cinématique ou à la statique. Vous pouvez voir les motivations des ingénieurs. Ce problème se résume essentiellement à quatre ou cinq équations linéaires et à une équation quadratique. Tout ceci paraissait simple jusqu'à ce que le logiciel MAPLE dise ``objet trop grand''. Après quelques bières et grattements de tête (feu Paul Erdos a dit qu'un mathématicien est une machine qui transforme le café en théorèmes ; les spécialistes en géometrie, du moins les Autrichiens, et les ingénieurs partagent la même affinité, mais pour d'autres ``lubrifiants''), une ligne a été placée sur l'axe z, l'autre coupant perpendiculairement l'axe x. Un peu d'algèbre de niveau école secondaire et un algorithme avec moins de vingt lignes a fini le travail. Résultat : un but à zéro en faveur de la géométrie!

Pas tout à fait, parce que cette simplification exige une transformation des coordonnées.

Dans ce cas, cela valait la peine parce que sinon la frustration aurait convaincu n'importe quel ingénieur de sacrifier un peu de sa dévotion pour les généralités pures au profit des résultats. D'un autre côté, on peut pousser les choses un peu plus loin. Un deuxième géomètre nous a rejoints et a dit ``Hah! moi je peux faire mieux, j'utilise une projection spéciale qui rendra trois des quatres lignes le long de chacun de leur axe mutuellement perpendiculaire''. Naturellement, après cette transformation, les choses sont plus simples, mais le pauvre homme a déclaré forfait en essayant d'obtenir la transformation dans les deux sens vers son merveilleux et trivial ``noyau''. Tout cela revient à dire que votre travail sera le reflet de ce que vous ressentez, de ce avec quoi vous êtes familiarisé, à qui vous avez parlé dernièrement et jusqu'à où vous êtes prêt à aller pour prouver que votre solution est la meilleure.

Auf Wiedersehen! il est temps d'aller à Budapest, et de sortir des arcanes, au moins pour un instant.

Soumis par le Prof. Paul J. Zsombor-Murray, de l'Université McGill, à l'heure actuelle en congé sabbatique à TU Graz. Ce texte a fait l'objet de l'éditorial du ntex2html_wrap_inline191 3, tome 21, 1997, des Transactions de la Société canadienne de génie mécanique.


De Re Historiae

I have just been appointed by the IFToMM Executive Council as Chair of the PC on History of TMM. It is my intention to promote activities such as symposia, organized sessions, and meetings to further develop the knowledge of History of TMM and mainly the awareness of a historical background within our disciplines in TMM and in the IFToMM Community at large.

As a first act I would like to ask our readers to submitt a paper on historical studies to the 10th IFToMM World Congress, as per the information supplied in this issue.

Also let me know if you are interested in attending to give a paper in a Conference on the History of TMM that could be organized by the Permanent Committee on History of TMM in the year 2000. I am looking for financial suport to help those who will need it to attend the Conference; in order to be more effective I have been suggested to have some letters of intention from potential participants, which can be submitted by E-mail. Indeed, the Conference will be organized only if a large enough number of persons will be really interested.

I shall appreciate any suggestions you may have on other colleagues who could be interested, also with the aim of having a first mailing list. Submitted by Prof. Marco Ceccarelli
cecca@ing.unicas.it


Nachruf

Am 1. Februar 1997 wäre der emeritierte Ordinarius für Getriebelehre an der Universität Rostock, Prof. Dr.-Ing.habil. Jörg Müller, 70 Jahre alt geworden. Im Jahre 1927 in Leipzig geboren, besuchte er dort die WILHELM-
WUNDT-Oberschule, an der er 1946 das Abitur ablegte. Von 1947 bis 1951 studierte er an der Fakultät für Maschinenwesen der damaligen Technischen Hochschule Dresden, u.a. bei solche namhaften Professoren wie HEIDEBROEK, BERNDT, WILLERS, NEUBER, FALTIN UND LICHTENHELDT, seinem späteren Doktorvater. Zum Erwerb praktischer Fähigkeiten absolvierte J. MüLLER bereits vor dem Studium und auch während der Semesterferien eine praktische Ausbildung in Großbetrieben des Gießereiwesens, des Verarbeitungsmaschinenbaus sowie des Schwertransportmittelbaus.
Nach einem Sonderstudienplan studierend, verteidigte er bereits vor Abschluß des vierten Studienjahres seine am Lehrstuhl für Getriebelehre bei Prof. LICHTENHELDT angefertigte Diplomarbeit zu dem Thema Konstruktion einer vollautomatischen Flachbeutelmaschine. Als wissenschaftlicher Assistent und Oberassistent wirkte J. MüLLER aktiv mit beim Aufbau des von Prof. LICHTENHELDT geleiteten Instituts für Getriebelehre, Feinmechanik und Textilmaschinen. Die Dresdner Schule für Getriebelehre fortsetzend, verteidigte er 1953 erfolgreich seine Promotionsarbeit Konstruktionsverfahren für acht- und zehngliedrige Kurbelgetriebe. Mit dieser Arbeit gelang es, die Eigenschaften der höhergliedrigen Koppelgetriebe zur Realisierung komplizierter Bewegungsaufgaben zu nutzen. Von 1954 bis 1961 war J. MüLLER als Entwicklungsingenieur und wissenschaftlicher Mitarbeiter bei CARL ZEISS JENA tätig und anschließend bis 1964 im Industrie-Institut der damaligen VVB Regelungstechnik, Gerätebau und Optik in Berlin. Während seiner Industrietätigkeit absolvierte er eine außerplanmäßige Habil-Aspirantur an der TU Dresden und verteidigte 1963 erfolgreich seine Habilitationsschrift zum Thema Theoretische und experimentelle Untersuchung zum Herstellen von Kurvenkörpern (Kurvenschablonen) im zwanglaufmechanischen Erzeugungsverfahren. Die Anregung zur Entwicklung eines solchen Verfahrens war von der polygrafischen Industrie ausgegangen. Im Zuge der Entwicklung der Fachrichtung Landtechnik an der damaligen Technischen Fakultät der Universität Rostock erfolgte seine Berufung zum Hochschuldozenten für Getriebetechnik im Jahre 1964. Eine Fülle von Lehraufgaben wie u.a. die Vorlesungen

 

  • Grundlagen der Getriebetechnik,
  • Konstruktionslehre der Getriebe,
  • Technische Kinematik und
  • Darstellende Geometrie
wurden von ihm wahrgenommen.

Im Jahre 1969 erfolgte seine Berufung zum Ordinarius für Getriebetechnik an die Universität Rostock. Seine Forschungsarbeiten konzentrierten sich seitdem entsprechend den Erfordernissen der Praxis auf das Schädigungsverhalten spezieller Baugruppen in Landma schinen, u.a. auf:

  • Rollenkettengetriebe, Zugmittel- und Rädergetriebe,
  • Schubkurbel- und Kurvengetriebe in Verbrennungsmotoren sowie
  • Welle-Nabe-Verbindungen.

Mit Nachdruck setzte sich J. MüLLER für die Überleitung der Forschungsergebnisse in die Praxis ein. Dies dokumentieren ca. 150 Veröffentlichungen in Fachzeitschriften des In- und Auslandes sowie die Monographie Getriebetechnik-Rollenkettengetriebe, die unter seiner Federführung entstand und 1983 im Verlag Technik, Berlin erschienen ist.

Des weiteren seien die von ihm vorbereiteten und durchgeführten Fachtagungen Getriebetechnik mit internationaler Beteiligung 1977 und 1987 in Rostock besonders hervorgehoben. Sie dienten vor allem auch der Kontaktpflege mit ausländischen Fachkollegen aus Ost und West. Die Pflege und Vertiefung internationaler Beziehungen kommt u.a. durch seine aktive Teilnahme an internationalen Kongressen und Symposien sowie durch Gastvorlesungen in Miskolc, Sofia, Wroclaw und Trondheim zum Ausdruck. Unmittelbar nach der ``Wende'' setzte sich J. MüLLER tatkräftig für die Hochschulerneuerung an der Universität Rostock ein. Durch seine aktive Mitwirkung konnte das Institut für Land- und Nahrungsmittelmaschinen am Fachbereich Maschinenbau und Schiffstechnik im Juli 1990 gegründet werden, dessen Leitung ihm übertragen wurde. Wer JöRG MüLLER als Hochschullehrer und Wissenschaftler näher kennengelernt hat, wird sich seiner bescheidenen aber gütigen und zielstrebigen Art gern erinnern. Sein wissenschaftliches Vermächtnis lebt weiter durch die Arbeit seiner Schüler.

Mitgeteilte von Prof. Dr.-Ing. habil. Kurt Luck, Fakultät Maschinenwesen, Technische Umiversität Dresden, Deutschland.


Books

  • Angeles, J. and Zakhariev, E. (editors), 1998, Computational Methods in Mechanical Systems. Mechanism Analysis, Synthesis, and Optimization, NATO ASI Series, Springer-Verlag, Heidelberg (in press). A collection of 16 lectures delivered at the NATO ASI on Computational Methods in Mechanisms held at Varna, Bulgaria, from June 16 to June 28, 1997. The book is organized in three parts: Kinematics of Mechanical Systems; Dynamics and Control of Rigid-Body Systems; and Dynamics of Flexible Multibody Systems. Topics cover a broad spectrum, from fundamentals to applications in analysis, design, and control of specific systems, such as advanced steering mechanisms in terrestrial vehicles, crashworthiness simulation, and robot design.
  • Gronowicz, A. and Miller, S., 1997, Mechanizmy-Metody Tworzenia Zbiorów Rozwiazan Alternatywnych. Katalog Schematów Strukturalnych i Kinematycznych (Mechanisms-Methods for the Generation of Sets of Alternative Solutions. A Catalogue of Structural and Kinematic Sketches), Politechnika Wroctex2html_wrap193awska Publishing Office, Wroctex2html_wrap193aw, Poland. The book deals with the problems of structural synthesis of mechanisms. Its first part (Chapters 2 and 3) gives the fundamentals of structural synthesis. The main part (Chapter 4) is a catalogue of many planar mechanisms. Mechanisms are classified in nine groups according with the type of motion of the input and output links. The output link can realize rotary (R), translatory (T) or general (O) motion, while the driving link is rotational (R), translatory (T) or of variable length (D). The readership to which the book is addressed includes both students of mechanical engineering and engineers, especially designers of machines and other engineering devices. The book is written in Polish but about 70% of its content comprises illustrations and formulas that should be understandable by any mechanical engineer working in the field.

    Submitted by Prof. A. Gronowicz, Wroclaw University of Technology, Wroclaw, Poland.

  • Rao, J. S., 1996, Rotor Dynamics (Third Edition), New Age International, New Delhi-London. The third revised and enlarged edition of this book presents an in-depth study of the dynamic behaviour of rotating and reciprocating machinery. It evolved out of lectures delivered at different universities, in Kharagpur, New Delhi, Kassel, Montreal, Lyon, Chia Yi, and Sydney over the last three decades; the first edition appeared in 1983. The book deals with torsional and bending vibrations of rotors, stability aspects, balancing, condition monitoring, and expert systems. Closed-form solutions are given where possible, as well as parametric studies, for a clear understanding of the subject. Both transfer matrix and finite element methods are given and practical cases of rotors presented. Special attention is given to transient analysis of the rotors, which is becoming an essential part of the design of high-speed machinery. Another special feature of the book is the treatment of fluid film bearings and squeeze film dampers. Cracked rotors, multi-spool geared rotors and other special topics are included. A first course on the theory of vibrations is a prerequisite to this study, ideally given to postgraduate students in Mechanical Design or as a special elective course to undergraduate students.

    Submitted by Prof. J. S. Rao, India Institute of Technology, New Delhi.

  • Rao, J. S., 1996, The Theory of Machines Through Solved Problems, New Age International, New Delhi-London. This book is written in the style of Schaum's series of solved problems; the subject of Theory of Machines or Mechanism and Machine Theory is first introduced to fresh undergraduate students. As there is no solved-problem book on this subject, there were several requests from various colleges in India which resulted in this work. This book contains 20 chapters. A total of 326 solved problems are given with several illustrations, and 138 additional problems are included for practice. A special feature of this book is the adoption of IFToMM terminology throughout the text. This book is also available on a floppy disk with the text in Amipro software and all solved problems in Autocad. The advantage of this is to provide the solutions on the screen so that the student can verify the steps (not included with the book). Three computer programs are available: CALOPL, which can be used to generate a mechanism, animate it, and analyze its velocity and accelerations; DYREMI, which provides rotating machine balancing, flywheel, reciprocating machinery balancing, force analysis of the engine parts; and CAMSOFT, a program that can be used to design a cam with specific inputs; all in accordance with the theories given in the book (Not included with the book); these two items can be provided on special request for the present.

    Submitted by Prof. J. S. Rao, India Institute of Technology, New Delhi.

  • Dietrich, M. and Kedzior, K., 1996, Lecture Notes of the ICB Seminars: Biomechanics and Biomechanics of the Spinal Systems, Warsaw, Poland.

    This volume contains the proceedings of the 37th Seminar of the International Centre of Biocybernetics (ICB) held in Warsaw in November 20th through 23rd, 1996. The symposium was organized jointly by the ICB and the IFToMM Technical Committee ``Man-Machine Systems''. The Institute of Aeronautics and Applied Mechanics, Warsaw University of Technology, and the Institute of Modern Civilisation, Warsaw, co-sponsored the Symposium.

  • Morecki, A., Bianchi, G. and Rzymkowski, C., 1997, RoManSy 11, Theory and Practice of Robots and Manipulators, Springer Verlag, Vienna.

    The proceedings of this eleventh edition of RoManSy focus mainly on problems of mechanical engineering and control.In his opening lecture, O. Khatib presented an overview of the ongoing efforts, at Stanford University, for the development of mobile manipulation systems and summarized the basic models and methodologies for their analysis and control. The 46 papers illustrate significant contributions in mechanics (10 papers), synthesis and design (4), walking machines and mobile robots (13), biomechanical aspects of robots and manipulators (2), control of motion (11), sensing and machine intelligence (3) and applications and performance evaluation (3). They appear here in the order and form in which they were presented in the various working sessions.

  • Angeles, J. and López-Cajún, C., 1997, Optimization of Cam Mechanisms (in Japanese), Nikkan Kogyo Shimbun, Tokyo. This is the Japanese edition of the original published in English by Kluwer Academic Publishers, Dordrecht, in 1993. The original was revised and translated by Dr. Masao Nishioka, R & D Director of Sankyo Manufacturing Co. Ltd., of Japan.

Theses

  • Zhang, Wen-Jun, 1994, An Integrated Environment for CAD/CAM of Mechanical Systems, Ph.D. Thesis, Delft University of Technology. The research described in this dissertation is aimed at developing a software environment (CIMOME) to integrate computer-based tools for designing and manufacturing mechanical systems (mechanisms in particular). The tools include those developed at the Laboratory of Mechanization of Production, of Delft University of Technology, in the past two decades and those commercially available. The function spectrum of the tools covers the whole life cycle of the machine development. Both theoretical studies and implementation have been carried out. The theoretical studies resulted in new observations and approaches to modern CAD/CAM systems, which have been verified through the implementation of a prototype CIMOME.

    Submitted by Prof. W. J. Zhang, City University of Hong-Kong, Kowloon, Hong-Kong.

  • Vasiliu, A. A., 1997, Une approche CAO pour la préconception des mécanismes plans générateurs de trajectoire: REALISME, Thèse de doctorat, École Centrale de Paris, Châtenay-Malabry, France.

    The use of neural networks for mechanism synthesis is proposed in this thesis. The idea is to model the application between the function of a mechanism, i.e., its performance or the value of the objective function representing the task or the optimal length of the trajectory it can reach along the desired one and its structure.

    In an example pertaining to the synthesis of planar mechanisms, the author uses a database of cases (about 30,000 different mechanisms) which have been simulated. Thereafter, he optimizes a neural network for matching this database. Finally, he uses this model for obtaining a mechanism which will be adapted to a new given trajectory out of the database. This approach is limited to dimensional synthesis, and is implemented in the software package REALISME.



A FIN-DE-SIECLE VIEW OF TMM tex2html_wrap_inline108

Jorge Angeles
Department of Mechanical Engineering
McGill University
Montreal, Quebec, Canada
angeles@cim.mcgill.ca

Abstract

A critical view of TMM at the end of the XX Century is attempted in this paper, with the aim of pointing out key issues that have to be addressed by the TMM community, if the discipline is to survive the current and foreseen technological developments and challenges.

Keywords:

theory of machines and mechanisms; mechanical systems; evolution

INTRODUCTION

Theory of Machines and Mechanisms, abbreviated TMM, is a term that seems to have been coined in Russia in the XIX Century [1]. The term was transferred to the West, and hence to the world, upon the foundation of The International Federation for the Theory of Machines and Mechanisms, IFToMM for brevity, in Zakopane, Poland, in 1969, during the Second International Congress on TMM. Henceforth, we will refer to TMM as the discipline.

A definition of the discipline, surprisingly, is not given in the otherwise quite comprehensive work of IFToMM's Commission A for the Standardization of Terminology [2]. However, TMM can be best understood via IFToMM's fields of activity, as per its Technical Committees, namely,

  • Computational Kinematics
  • Gearing
  • Linkages and Cam Mechanisms
  • Man-Machine Systems
  • Mechatronics
  • Micromechanisms
  • Nonlinear Oscillations
  • Robots and Manipulators
  • Rotordynamics
  • Transportation Machinery

We can thus realize that the subdisciplines encompassed by TMM cover a rather broad spectrum, their common denominator being mechanical systems.

 

THE RECENT EVOLUTION OF TMM

To say that tracing back the origins of TMM--as those of any human activity, for that matter--is a difficult task would be an understatement. We shall not attempt here to give a historical account of the discipline, but rather focus on its development in the last three centuries, with the sole purpose of putting this paper in perspective. Moreover, since TMM relies first and foremost on kinematics, the development of the former is intertwined with that of the latter. The milestones that we can cite in connection with the development of TMM in the time span of interest are listed below:

 

  1763:
Giulio Mozzi introduces the concept of screw axis [3].
  1776:
Leonhard Euler shows that every rigid-body rotation about a fixed point leaves a line of the body fixed, which is nothing but the axis of rotation [4].
  1808:
P. Lanz and A. Bétancourt, Ecole polytechnique (Paris), publish Essai sur la Composition des Machines.
  1811:
J. N. P. Hachette, Ecole polytechnique (Paris), publishes Traité Elémentaire des Machines.
  1829:
A. Schubert, TU Dresden, introduces the pressure angle of cam mechanisms.
  1830:
Michel Chasles in France and Gaetano Giorgini in Italy prove rigorously the existence of Mozzi's screw axis.
  1840:
Olinde Rodrigues derives a formula relating the unit vector parallel to the axis of rotation and the angle of rotation with the original and the final position vectors of a point of a rigid body undergoing a rotation about a fixed point. Additionally, Rodrigues derives the formula for the composition of rotations and proposes what is now known as the Euler-Rodrigues parameters or quaternions.
  1841:
Robert Willis, Cambridge University, publishes his Principles of Mechanisms.
  1844:
Sir William Rowan Hamilton invents quaternions [5]
  1872:
S. Aronhold discovers the Theorem of Three Centers.
  1875:
Sir Robert Stawell Ball publishes ``The Theory of Screws. A Geometrical Study of the Kinematics, Equilibrium, and Small Oscillations of a Rigid Body''.
  1875:
Franz Reuleaux publishes Theoretische Kinematik, Gründzuge einer Theorie des Maschinenwesens 1.
  1886:
A. B. W. Kennedy discovers, independently from Aronhold, the Theorem of Three Centers.
  1895:
Lorenzo Allievi publishes his Cinematica della Biella Piana in Naples.
  1903:
E. Study publishes Geometrie der Dynamen.
  1955:
Jacques Denavit and Richard S. Hartenberg introduce a kinematic notation aimed at the algebraic analysis of spatial kinematic chains with the aid of matrices [6].
  1958:
Jacques Denavit introduces dual matrices in the analysis of mechanisms [7].
  1959:
Joseph S. Beggs establishes the Aronhold-Kennedy Theorem in three dimensions in Ein Beitrag zur Analyse Räumlicher Mechanismen, Doctoral Dissertation, TH Hannover.
  1963:
A. T. Yang publishes Application of Quaternion Algebra and Dual Numbers to the Analysis of Spatial Mechanisms.
  1965:
I. I. Artobolevskii publishes his Teoriia Mashin i Mekhanismov.
  1965:
The First International Congress on Theory of Machines and Mechanisms is held in Varna, Bulgaria.
  1969:
The International Federation for the Theory of Machines and Mechanisms is founded in Zakopane, Poland, during the Second International Congress on TMM. Its first President is Acad. I. I.\ Artobolevskii.
  1978:
F. M. Dimentberg publishes Teoriia Vintov i ee Prilozheniia (Theory of Screws and its Applications.)
  1978:
Oene Bottema and Bernard Roth publish Theoretical Kinematics.
  1988:
The First International Workshop on Advances in Robot Kinematics is held in Ljubljana.
  1988:
Hongyou Lee (a.k.a. Hongyou Li) reports the solution of what is called the inverse kinematic problem, named ``the Mount Everest of Kinematics'' by F. Freudenstein.
  1991:
A Symposium on the First Forty Years of Modern Kinematics is held in Minneapolis to honor Ferdinand Freudenstein. The proceedings of the symposium are collected in book form [8].
  1993:
The First International Workshop on Computational Kinematics is organized in Schloß Dagstuhl, Germany, with the participation of thirty-plus kinematicians, geometers, mathematicians, and computer scientists.
  1994:
Manfred Husty proposes an algorithm to derive the 40th-degree characteristic polynomial of a general platform manipulator.

 

The evolution that we see above is remarkable: TMM has evolved in merely two and a half centuries from a rather empirical discipline to one that is well established within the realm of mechanics, while embracing geometry, algebra, electronics, and computer science. This evolution, on the other hand, is but an instance of the evolution of science and engineering, as prompted by the advent of the information age, best summarized by Strang [9] as

 

Solving a problem no longer means writing down an infinite series or finding a formula like Cramer's rule, but constructing an effective algorithm.

In the above list of milestones, 1991 is recognized as the 40th anniversary of modern kinematics. What marked the emergence of modern kinematics is the electronic computer, which enabled the development of what came to be known as Computer-Aided Design or, in a more general context, Computer-Aided Engineering. The first 40 years of modern kinematics can thus be characterized by an intensive search for the numerical solution of traditional kinematics problems that were recognized as unsurmountable with drafting instruments, paper, and pencil.

The numerical aspect of those forty years came about naturally, as one of the first functions of the electronic computer was number crunching, the other one being data organization--hence the French name ordinateur for this machine, which was first regarded as a device to order data. Moreover, the most impressive developments in numerical analysis came in the fifties and the sixties; for example, the concept of numerical conditioning of a problem, which had been puzzling numerical analysts during World War II, was first identified by Wilkinson after the war. George E. Forsythe, widely acknowledged as the founder of modern numerical analysis, gave a lucid explanation of numerical conditioning by pointing out the difference between computing by longhand calculations and doing it with an electronic computer, in a famous paper [10]. Furthermore, the sixties saw the rise of Fortran as the universal language for scientific computing; with this came IMSL, the American standard package of scientific routines for numerical computations. The development of modern kinematics and, with it, of modern TMM was made possible thanks to IMSL and its counterparts elsewhere, like NAG in the UK.

Up until the fifties, the practice of kinematic analysis and synthesis was largely circumscribed to graphical methods, although theoretical kinematics had reached a stage of maturity at the turn of the century. To a great extent, it was the pioneer work of Freudenstein [11] in the United States and of Levitskii and Shakvazian [12] in the former Soviet Union that paved the way to modern kinematics. Needless to say, the impact that this work has had over the last 40 years in the development of TMM would not have been possible without the concurrent advent of the digital computer. The work of these pioneers is now considered to have drawn the line that separates classical from modern kinematics. Almost simultaneously appeared the work of Denavit and Hartenberg [6] on a systematic description of spatial kinematic chains that is suitable for algorithmic implementation. In the mid sixties, the digital computer had already become a commonplace tool in engineering, and TMM could not escape its influence.

Not too long after the advent of the electronic computer a breakthrough in computer technology was recorded: Intel introduced its first microprocessor in 1971, which paved the way to robotics and automation. The microprocessor allowed the real-time control of systems and processes, and opened new avenues for the development of TMM. At the same time, it posed new challenges to researchers in the discipline: The body of knowledge comprised in classical mechanics was soon discovered to be unsuitable for direct application in the control of robots. Indeed, Hollerbach [13] pointed out that, if the classical Euler-Lagrange equations were to be programmed with the purpose of applying them to the real-time computed-torque control of a six-axis robotic manipulator, roughly 120,000 flops--floating-point operations--would have to be performed per sampling period, which was bordering at the limit of computer technology in the late seventies. Work thus intensified in the eighties aiming at the devising of real-time-implementable algorithms that would allow their application to the control of robots. Research in this area led to quite efficient algorithms that consume as little as 1,000 flops for the same purpose.

In the realm of kinematics research, Freudenstein's ``Mount Everest of kinematics problems'' kept researchers quite busy for over a decade. In the process of finding solutions for what is called the inverse kinematic problem (IKP), reasearchers soon discovered that a purely numerical approach would not be enough to answer fundamental questions like ``what is the number of postures with which a general six-revolute manipulator can pose its end-effector?'' Fortunately, computer science research in the seventies led to a reliable piece of software for computer algebra, Macsyma, which could be applied to eliminate unknowns from a system of polynomial equations; this is just what was needed to solve the IKP.

Computer algebra made it possible to devise an algorithm for the solution of the IKP, which was thus found to admit up to 16 solutions. Having left the IKP behind, researchers embarked on an even more challenging problem: the direct kinematics of a general six-degree-of-freedom platform manipulator. A platform manipulator of general architecture consists of two platforms connected by six legs, each consisting of a six-axis open kinematic chain. The usual layout of the legs gives rise to an SPU chain, since the first three revolute axes intersect, thereby forming a spherical or S joint, and so do the last two, which thus form a universal or U joint. The manipulator is actuated by means of hydraulic jacks located at the joint lying between the S and the U joints, which is thus a prismatic or P joint. Furthermore, the centers of the S joints connecting the leg to the base platform as well as those of the U joints connecting the moving platform to the leg, observe arbitrary layouts in the base and in the moving platform, respectively.

Although the question of whether Husty's 40th-degree polynomial is minimal, i.e., of whether a general platform manipulator with six degrees of freedom actually admits 40 poses of its moving platform for a given set of six leg lengths, is still to be answered, this problem is essentially solved. What the foregoing discussion indicates is that the solution of current problems in mechanisms calls for the merging of various disciplines; computer science, geometry, algebra, and kinematics were needed to devise the aforementioned algorithm.

 

THE CHALLENGES THAT LIE AHEAD

The ultimate function of a machine being to satisfy a human need, the purpose of fundamental research in TMM should be to end up with such a machine. Engineers at large, but to a great extent those working in TMM, face challenges brought about by the population growth that we have seen in the current century. Feeding the six-billion-plus inhabitants of the Earth, most of whom live under conditions of extreme poverty, is the major challenge that is posed to engineers of our discipline. Satisfying to the needs of this huge populatiom calls for an increase in productivity, which can be simply stated as producing more with less. The need to increase productivity to unprecedented levels calls for unprecedented solutions, which takes us TMM engineers and researchers to developing unheard of machine performances in terms of speed, accuracy, economy, and reliability.

Current serial manipulators are capable of speeds of 1 m/s at the tip of their end-effector. Raising this speed calls for original solutions that are yet to be found. As a means of increasing the operation speed of robotic manipulators, parallel robots have been proposed. One such machine, the Delta robot, was designed [14] as a three-dof positioning manipulator. Later on, this machine was enhanced with orienting capabilities, thereby ending up with a six-dof parallel manipulator, the Hexa robot [15], that has recorded tip speeds of 3 m/s. This increase in speed was attained by placing all six motors at the base, which is made possible by the special architecture of parallel manipulators. While a three-fold increase in speed performance is an impressive gain, it is not yet an increase by an order of magnitude in tip speeds. In order to attain higher operation speeds, dramatic innovations in the mechanical transmissions and in the control systems of parallel manipulators will have to be put in place.

The control of parallel manipulators for path-tracking operations requires comparing the current pose of the end-effector with the nominal one, which calls for an on-line direct kinematics solution. It is out of the question to compute the 40 real and complex, actual and spurious solutions of the general parallel manipulator at every sampling instant, because of the huge computational overhead involved. Alternatives to this purely kinematic approach to manipulator control have been proposed that call for redundant sensors. The task of the TMM engineer is then to decide (i) how many extra sensors to place on the manipulator--besides those required by the local controller, to keep track of the controlled leg lengths--so as to ease the computational burden of the control system without increasing unnecessarily the cost of the machine, (ii) where to place the extra sensors, and (iii) how to manage the information flow and processing.

The above discussion thus leads us to realize that TMM as we knew it in the sixties is no longer sufficient to face the challenges that lie ahead. The traditional subdisciplines of TMM will have to be merged with new technologies like sensor fusion, mechatronics, and many others that are as yet to be developed.

The TMM engineer should be equipped with the education needed to face the aforementioned challenges, which calls for new attitudes toward the teaching of TMM. The traditional TMM curriculum comprising courses on kinematics and dynamics of machines will have to be revised to include chapters on sensing and actuation, while at the same time complemented with emerging disciplines. Kinematics and dynamics alone are no longer enough to solve the current technological problems and to propose novel solutions to these problems. TMM has to be studied now as a discipline that involves, at its very core, the processing of information in a reliable manner. It is impossible nowadays to design and manufacture machines without the intervention of the computer. The ``computer-aided'' qualifier that gained so much popularity in the seventies is thus rapidly becoming an obsolescence.

 

CONCLUSIONS

If TMM is to survive the current and foreseen technological developments brought about by the information age, new attitudes toward the teaching, research, and applications of the discipline will have to be brought about. Algorithm development and implementation is becoming a fundamental activity of TMM, and hence, a strong background in computer science and electronics, besides classical kinematics and dynamics of machines, is required in the education of TMM engineers.

 

ACKNOWLEDGEMENTS

Professor Marco Ceccarelli, University of Cassino, Italy, is thankfully acknowledged for his help in producing the milestones of Section 2. The participation in this conference was made possible by the Natural Sciences and Engineering Research Council, of Canada.

 

REFERENCES

 

  1. Artobolevskii, I. I., Bernstein, S. N., Bruevich, N. G., Vinogradov, I. M., Kolmogorov, A. N., Krylov, A. N., Leibenson, L.\ S., Smirnof, V. I., Sobolev, S. L., Delone, B. N., Goncharov, 1948, Polnoe Sobranie Sochinienii P. L. Chebysheva. Tom IV: Teoriia Mekhanismov (Complete Works of P. L.\ Chebyshev. Vol IV: Theory of Mechanisms.), Akademiia Nauk SSSR, Moscow-Leningrad.
  2. IFToMM Commission A for Standardization of Terminology, 1991, Mechanism and Machine Theory, Vol. 26, No. 5.
  3. Mozzi, G., 1763, Discorso Matematico Sopra il Rotamento Momentaneo dei Corpi, Stamperia di Donato Campo, Naples.
  4. Euler, L., 1776, ``Nova methodus motum corporum rigidorum determinandi,'' Novii Comentarii Academiæ Scientiarum Petropolitanæ, Vol. 20 (1775) 1776, pp. 208-238 = Opera Omnia Vols. 2-9, pp. 99-125.
  5. Hamilton, W.R., 1844, ``On quaternions: or a new system of imaginaries in algebra,'' Phil. Mag., 3rd. ser. 25, pp. 489-495.
  6. Denavit, J. and Hartenberg, R.S., 1955, ``A kinematic notation for lower-pair mechanisms based on matrices,'' ASME J. Applied Mechanics, Vol. 77, pp. 215-221.
  7. Denavit, J., 1958, ``Displacement analysis of mechanisms based on matrices of dual numbers'', VDI Berichte, Vol. 29, pp. 81-89.
  8. Erdmann, A. G. (editor), 1993, Modern Kinematics. Developments in the Last Forty Years, John Wiley and Sons, Inc., New York.
  9. Strang, G., 1988, Linear Algebra, Third Edition, Harcourt Brace Jovanovich College Publishers, Fort Worth.
  10. Forsythe, G. E., 1970, ``Pitfalls in computation or why a math book isn't enough'', American Mathematical Monthly, Vol. 77, pp. 931-956.
  11. Freudenstein, F., 1954, ``An analytical approach to the design of four-link mechanisms'', Transactions of the ASME, Vol. 76, pp. 483-492.
  12. Levitskii, N. I. and Shakvazian, K. K., 1954, ``Synthesis of spatial four-link mechanisms with lower pairs'', Trudy Seminara Po Teorii Mshin i Mekhanizmov, Akademiia Nauk SSSR, Moscow.
  13. Hollerbach, J.M., 1980, ``A recursive Lagrangian formulation of manipulator dynamics and a comparitive study of dynamic formulation complexity,'' IEEE Transactions on Systems, Man, and Cybernetics, Vol. SMC-10, No. 11, pp. 730-736.
  14. Clavel, R., 1988, ``Delta, a fast robot with parallel geometry,'' Proc 18th Int. Symposium on Industrial Robots, Lausanne, pp. 91-100.
  15. Pierrot, F., Fournier, A., and Dauchez, P., 1991, ``Towards a fully-parallel 6 dof robot for high-speed applications,'' IEEE International Conference on Robotics and Automation, Sacramento, pp. 1288-1293.