IGMR mechanism lexicon: interactive, internet-based knowledge repository

gt lexikon

The IGMR mechanism lexicon [Ni00, Ni03] was the first step towards an interactive, internet-based knowledge repository (Fig. 1). It is based on the IGMR's large collection of mechanism models, which was systematically collected at an early stage and is intended to provide assistance in the development of kinematic designs for solving motion tasks. The main focus is on the principle synthesis of non-uniform transmissions. The mechanism lexicon therefore includes a collection of gearing solution principles as well as numerous application examples. Thanks to its computer-based implementation, the gear lexicon offers considerable advantages over knowledge stores in the form of books and catalogues in paper form, which can be utilised to advantage in the design of non-uniformly translated gear units.


Beginning in 1988 [Di88] a series of nearly sixty transmission descriptions with detailed theoretical background and the relevant design equations and diagrams [Di95/1] were developed. So far, about half of these transmission descriptions have been included in the mechanism lexicon. The content of the mechanism lexicon consists of descriptions of gearing principles, the representation of suitable gearing structures and descriptions of application examples. The content is always assigned to the motion tasks for which they are suitable for. Furthermore, selected technical terms which are necessary for the description of motion tasks and movement devices are explained in the mechanism lexicon. To make orientation easier, the four chapters are each marked with a colour (Fig. 2), which indicates the affiliation of each page as a stripe on the left margin. The alphabetical order of the keywords is used as a further classification criterion within the four chapters as is customary in lexicons. Appropriate controls allow the developer to access the contents of the lexicon. In addition to information access with the help of the classification criteria related to the keywords, the lexicon also provides for the use of various search functions.


In addition to the versatile forms of knowledge presentation, the mechanism lexicon is intended to support the user equally in the application of the treated knowledge. Application programs that are available for the synthesis, analysis or simulation of transmissions should therefore be connected to the lexicon at an appropriate place. For example, when describing transmission functions, it is advisable to offer suitable prepared worksheets of a mathematical program (Fig. 3), which allow the user to calculate the transmission function and its derivatives for specific kinematic dimensions of a transmission. It is also very helpful to integrate analysis and synthesis programs that allow the use of appropriate interpretation methods.


With the help of a classification system for describing motion tasks developed for the mechanism lexicon, the basis was laid for a search form that was included in the mechanism lexicon (Fig. 4). It is equally suitable for the search for executed example transmissions as well as for transmission solution principles. By selecting appropriate properties, the user determines the search criteria with which a search is to be carried out. The contents stored in the encyclopedia are determined, which correspond to the specified search criteria. The result is a list of these contents. Thus, in addition to the already described access options through the standard operating elements, which are all word-oriented, the lexicon offers a special possibility to retrieve suggestions for solutions with regard to a given task. The search form can be called up either by pressing a button in the menu bar of the help system or by an entry in the table of contents. It consists of standard form elements of the HTML language and is divided into three areas: transmission structure, transmission tasks and management tasks.


When searching for a suitable solution, it may be necessary to carry out a preliminary design in order to better assess the suitability of a suitable transmission structure. In addition, there are numerous graphic synthesis and analysis methods that can be used advantageously in this phase of development. It is shown that such graphic constructions can be carried out with the help of geometry programs on the computer. One program that offers this possibility is the interactive geometry program Cinderella. This program allows the creation of geometric constructions on the computer in a simple, intuitive way. It is a mouse-executed, interactive geometry program in which the basic elements of the construction can be "grasped" and moved with the mouse after the construction has been completed. The whole construction follows the movement in a consistent manner, so that the "dynamic" behaviour of the geometric construction can be explored in a very descriptive way [Cs01]. In addition, the geometry program can also be used to display local curves, a feature that is of great importance for applications in gear technology. In the simplest case, this functionality can be used to display the coupling curves of gears (Fig. 5), but also, for example, polar orbit or center point curves.


The KINTOP program was developed at the Institute of Mechanism Theory, Machine Dynamics and Robotics for kinematic analysis of planar crank gears and gear units. With the program it is possible to calculate the motion parameters (position, speed, acceleration) of all transmission elements and to generate motion animations. Trajectories, velocity and acceleration vectors as well as velocity hodographs of any point can be displayed. For some of the transmissions, which are integrated in the mechanism lexicon as examples, there are already data sets for simulation using the KINTOP program. In this way, the function of a transmission can be clarified more clearly, and the developer can thus better assess whether a transmission is suitable for solving a particular motion task. Fig. 6 shows as an example the short description of a transmission for guiding a plough blade. By clicking on the KINTOP symbol, the program with the corresponding data set can be called up.

The current web version of the mechanism lexicon can be found in the Services section.



Institute of Mechanism Theory, Machine Dynamics and Robotics

RWTH Aachen University

Eilfschornsteinstraße 18

52062 Aachen



Phone: +49 241 80 95546

Fax:      +49 241 80 92263


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