Q: What is CoMeT?
A: CoMeT is a conceptual design tool used to aid in the synthesis and design of compliant mechanisms. The software enables a user to sketch a mechanism concept and then perform rapid, kinematic/stress analysis. This is completed by converting a hand sketch of a mechanism design into mathematical equations which are solved by Matlab, and the converted equations back into a sketch for qualitative/quantitative interpretation of results. The design and analysis process is accomplished rapidly since the sketching interface eliminates the need to construct a formal parametric model (e.g. CAD, points, lines, surfaces, volumes) and eliminates the need to mesh the model. With this tool, designers can:
- Test feasibility of design concepts (without time needed to build a CAD/FEA model, mesh, post process, etc…)
- Obtain answers within 5 – 10 % of measured values
- Rapidly converge on an optimum concept design
- Develop their engineering intuition about compliant mechanism
Q: How do I obtain CoMeT?
A: At present, we are distributing CoMeT-lite, a modified version of CoMeT (see next question). It is free to download/use for all academic, university research, government research and educational purposes. CoMeT-lite is not free to use for commercial applications. The software is available for download.
Q: Is there a User Guide and tutorials for CoMeT?
A: Yes, the User Guide contains instructions on the software function and use. Tutorial exercises are provided within the User Guide. Videos showing the completion of the tutorials are contained within the software download. See the User Guide for instructions on launching the videos. The User Guide may be downloaded here.
Q: How do I install CoMeT-lite?
A: The downloaded executable should walk you through the setup. If you have problems, you should double check your version of Matlab and reference the Users Guide on the installation process. You should also make sure that Matlab is installed PRIOR to the installation of CoMeT/CoMeT-lite. The information you find here can fix typically 80% of the installation problems we’ve experienced to date.
If you have installed Matlab but still cannot install CoMeT, you can add a registry key which will allow you to override the Matlab requirement:
- Start -> run -> regedit
- Navigate to HKEY_LOCAL_MACHINE\SOFTWARE\MathWorks\MATLAB
- Right-Click on MATLAB
- Choose New->Key. Name the key COMET_OVERRIDE
- Right-Click on COMET_OVERRIDE
- Choose New->String Value. Name the String Value MATLABROOT
- Double-click on MATLABROOT. In the Value Data box, type the path where CoMeT is to be installed, e.g. D:\CoMeT
If you are still having trouble, you may contact Prof. Culpepper, culpepper “at” mit.edu.
Q: What is the difference between CoMeT and CoMeT-lite?
A: CoMeT is a compliant mechanism design software with four modes
– Editor: Mode in which the mechanism and boundary/loading conditions are constructed
– Analysis: Mode in which the model is solved to determine static deformations, stress/strain and kinematic behavior.
– Optimization: Mode in which the geometry of models may be changed via an optimization routine to optimize mechanism characteristics for a given set of inputs.
– Sensitivity: Mode in which models may be assessed to determine sensitivity of performance to geometric, loading and material uncertainties
CoMeT-lite is contains fully functional versions of the Editor and Analysis modules.
Q: Does CoMeT/CoMeT-lite run on a Tablet PC, Desktop, Laptop, or all of them?
A: CoMeT was designed to work best with a Tablet PC. The sketching utility of the Tablet is particularly helpful. CoMeT/CoMeT-lite may be run on a Laptop or Desktop by using the traditional mouse/screen.
Q: Is CoMeT-lite a stand alone software package?
A: No, CoMeT requires Matlab (Tested on version 6.5.1 or higher, will probably run on the few preceding versions of Matlab) to run. CoMeT-lite is launched from within the command line prompt of Matlab.
Q: Who do I call for help/support?
A: Contact Prof. Martin L. Culpepper (culpepper “at” mit.edu)
Q: Where did CoMeT come from?
A: CoMeT was funded via the Microsoft iCampus project (http://icampus.mit.edu/) as part of the RobotWorld project for technology-based Teaching Infrastructure. Continued funding for CoMeT has been provided through an NSF grant from the DMII Nanomanufacturing program under Career Grant: #0348242 – CAREER: Research and Education Plans for Modeling and Design of Fixtures and Six-Axis Manipulators for Nanomanufacturing. The software was developed by Prof. Martin Culpepper and graduate student Patrick Petri as part of an MS research thesis.
Q: How is CoMeT used at MIT?
A: CoMeT is used in research and teaching activities at MIT
Use in the classroom:
(1) An exploratory learning tool – The sketching and analysis components enable students to rapidly explore many designs and learn about screw axes (3D), virtual centers of rotation, stress, strain and stiffness. Through exploration, students gain a working sense of compliant mechanism fundamentals.
(2) A project design tool – CoMeT-Lite can be used to enhance learning in students’ compliant mechanism projects. Students can spend more time on the project’s learning goals rather than devoting project time to learning a CAD program and/or an FEA program. This can be done without losing sight of the important fundamentals of the analysis. CoMeT-Lite is used at MIT (2.000: How & Why Machines Work–psdam.mit.edu/2.000/start.html) by students to design compliant robotic nano-manipulators.
CoMeT has been used in the undergraduate curriculum (2.000 How and Why Machines Work, http://ocw.mit.edu/courses/mechanical-engineering/2-000-how-and-why-machines-work-spring-2002/ ) and in graduate curriculum (2.76 Multi-Scale System Design and Manufacturing, http://ocw.mit.edu/courses/mechanical-engineering/2-76-multi-scale-system-design-fall-2004/ ).
Q: What is planned for the future of CoMeT?
A: We are steadily adding extra functionality to the software. Updates will be announced as they are made ready.
Use in compliant mechanism research:
CoMeT-Lite has been used at MIT to synthesize 1st order designs of compliant mechanisms for robotics applications and award winning Nanomanipulation equipment.