A new nonlinear gain structure for PD-type controllers in robotic applications

Abstract

This article introduces a generic enhancement to certain proportional plus differential (PD)-type, joint-space controllers for robotic manipulators that can be utilized to reduce peak levels of servo output without increasing the duration of the transient response. This enhancement takes the form of nonlinear, partially hyperbolic multipliers that are applied to re-scale the error signal gains. The rationale prompting the design of the aforementioned gain structure is discussed at length, and a mathematical formulation of the modified control law is presented for application to both position and full trajectory control. The stability of the suggested control strategy is addressed, and numerical simulations involving a three degree of freedom (3-DOF) robot model are presented to demonstrate quantitatively the potential benefits of implementing such. ©1999 John Wiley & Sons, Inc.