What is a Compliant Mechanism?

A mechanism is a device that transfers or transforms motion, force, or energy in order to perform work. Traditional rigid-body mechanisms contain moving parts and joints, such as gears and pins, which work together in order to carry out the function of the mechanism. Compliant mechanisms, on the other hand, work by flexing all or some of their parts. A few examples that come to mind are a spring, tweezers, and a bow-and-arrow. Many devices, such as a stapler, are a combination of rigid-body and compliant mechanisms.


One of the advantages of compliant mechanisms is their ability to be miniaturized. They can be injection-molded out of one piece of material, or manufactured in the same manner as integrated circuits. This makes them ideal candidates for use in microelectromechanical systems (MEMS).


Compliant mechanisms are more difficult to design well than their rigid-body counterparts. Predicting their actions, and the effect of stress and fatigue over their lifespan, requires an iterative design process. This process can be lengthy, particularly for inexperienced designers who lack a “big-picture” view of what goes into good design and why.

Enter CoMeT

CoMeT was created to shorten the compliant mechanism design process. The goal was to enable the designer to gain a “big picture” view of the critical facets of compliant mechanism design, fabrication and use, and to develop a simulation tool that may be used to generate and evolve new compliant mechanism designs.

Using a tablet PC, a designer can draw a preliminary sketch of a mechanism. CoMeT converts this sketch into matrix equations that are analyzed by Matlab, and then converts the Matlab analysis back to a sketch (flexed mechanism) and numerical data (stresses, displacements and screw axis characteristics) that are interpreted by the designer. This process is repeated until a final design is reached, which (thanks to CoMeT) can occur in minutes instead of hours.

Exploring and Using CoMeT