Advanced control of high performance drives in robotics

Abstract

This paper deals with the application of VSS (Variable Structure System) theory for an electrical drive with sinusoidal brushless permanent magnet motor. An adaptive model following control (AMFC) loop is added in order to rebuild the back e.m.f. coefficient. The identification of the back e.m.f. coefficient allows to cancel the non-linear term due to the back e.m.f. by means of a feedforward compensation. A variable structure controller is proposed in order to increase the performance of standard PID regulators. To suppress chattering at steady-state the conventional VS control laws are modified, with simple tuning rules. The controller has been implemented on a transputer and generates the signals nedded to control the inverter: this technique allows an extremely fast modification of the control parameters. Simulations and experimentaal results are reported to show the performance improvements obtainable by using the proposed control technique.