Speaker: Chong Peng

Advisor: Dr. R. S. Sodhi

ABSTRACT

A new optimal or approximate mechanism synthesis method for motion and path generation is developed. According to the nature of synthesis problems, we uses crank length error as objective function. In precise synthesis, the moving pivot of the crank, which moves with the moving plane, should have a circular path. Thus the goal of optimal synthesis can be stated as finding a point on the moving plane whose path is mostly close to a circle. Selecting the coordinates of the center and circle points as design variables, we minimize the fluctuation of the distance between the circle point and the center point while the circle point is moving. Solving the optimization problem, we find the center and circle points and then the linkage which achieves the prescribed positions with the minimum error.

This method has several advantages over traditional optimal synthesis methods, which use structure error (the error between generated and desired motion) as objective function. The objective function in this method is much easier to construct than in the traditional ones. The new method is more compatible. For many kinds of synthesis problems, its objective function has the same form, so it can be applied to many synthesis tasks with only a few adjustments. This method can also be used for spatial mechanism synthesis. The disadvantage is that this method is not capable of dealing with order problem because the crank angle is not included in the design variables.

Synthesis examples are given for the planar motion and path generation. Future work includes the application of this method to spatial mechanisms, infinitesimally separated positions, adjustable mechanisms and so on.