ROBOT LINK AND CONTACT SURFACE DYNAMIC INTERACTION - AN EXPERIMENTAL-STUDY OF CONTACT TASK INSTABILITY

In this article we explore, both theoretically and experimentally, the effect of multiple structural compliance sources on robot stability d uring contact task execution. Here we examine the effect of link compl iance and compliance of the contact surface on overall system stabilit y. Using the theory associated with singularly perturbed dynamic syste ms, the stability of the robotic system is examined for three distinct cases: (1) link stiffness much greater than contact surface stiffness ; (2) contact surface stiffness much greater than link stiffness; and (3) link stiffness comparable to surface stiffness. Theoretical result s lead to a conclusion of stability only for case (1). Experiments ind icate stable behavior for all these cases. Through the use of singular perturbation modeling and analysis, we are able to write dynamic mode ls of the robot during contact with a complaint surface such that the complaint behavior of the robot links and contact surface are paramete rized with just two variables. In doing so, theoretical examination an d experimental study of stability, or the lack thereof, is greatly sim plified. Instead of exhaustive tests in which experiments or stability analyses are conducted over a wide range of values of link and contac t surface compliance, a select number of cases are examined. Under the assumptions that validate the use of singular perturbation modeling t echniques, the resultant stability analysis and experimental results a re hence conducted in an efficient manner. (C) 1997 John Wiley & Sons, Inc.