Introducing fundamental concepts of control: A case study in robot force control

This paper describes an approach to teaching concepts of automatic control, aimed principally at mechanical engineering students on courses that do not include a dedicated control module. The application area employed is robot force control, which has been the focus of much research during the past three or more decades. In this work, a robot is modelled in MATLAB and Simulink as a simple one degree-of-freedom ‘arm’, which is based upon a velocity controlled DC motor. The paper describes the development of this model and how it can be approximated as a standard second order system from step response data. Three example solutions for designing a suitable force controller are then discussed, for a situation where the stiffness of contact at the robot/task interface is known and constant. The approach can be used in conjunction with a more traditional course in automatic control, or act as standalone tutorial for those with a more specific interest in force control