Servomotor modelling and control for safe robots

This paper presents a method of modelling and control of servomotor for safe robots. Safety has indeed come to represent one of the major themes in robotics research for those applications that bring robots in contact with humans. Beyond this is the classical research topic of impedance control which has recently found new interest after the progress in the improved control and sensing principles. There exist a few different strategies for robot impedance control, where different amounts of sensor information are used. Among them, a kind of sensorless force control, torque observer method based on motor model, current and position information has many advantages and is widely researched. This paper discusses the permanent magnet synchronous motor (PMSM) modelling and control for the sensorless force control of safe robots. DSP controller for performing the vector and current control functions for a PMSM is implemented, and field oriented control is used to convert the PMSM into equivalent separately excited dc machines which have highly desirable control characteristics. Also, the nonlinear equations of the PMSM, PID controller equations and a real time model of the inverter switches are used in the simulation. At last, key theoretical results are verified by loading experiments.