Development of the Tri-Level Variable Rate Trajectory With Discretely Vanishing Shock for Optimum Design

Abstract

The tri-level variable rate trajectory is a general motion which can be applied to programmable controllers, robotic manipulators, mechanisms, and mechanical devices where the input crank orientation, velocity, and acceleration vary with time. In the work presented here, the tri-level variable rate trajectory is an extension of the variable-rate trans-symmetric motion developed by the first author in 1984. That motion and the one developed here consist of discrete segments of constant and linearly varying accelerations occurring over specified time intervals, thereby providing versatile programmable trajectories with several advantages over the constant acceleration motion, simple harmonic motion, cycloidal motion, and the popular polynomial trajectories used in robotics. The tri-level variable-rate trajectory allows much more control of the acceleration contour of the motion and as a result, there is a decrease in the power required, a decrease in the operating cost, and a decrease in dynamic responses such as shock, vibration, and shaking force and virtual elimination of the overshoot problem that sometimes accompanies the polynomial segment motions. This is a general method which can be applied to many applications. The results of applying this trajectory to a complex machine controller are presented as an example.