Brushless servo motor control using variable structure approach

The variable structure system (VSS) is expected to be a powerful tool for constructing a control strategy for AC machines since it is based on discontinuous control inputs, i.e. variable structures. The application of VSS to the position control of a brushless servo motor is discussed. The resulting system is robust with respect to parametric variations and disturbances. On-off patterns for switching devices are generated directly by VSS, and the robustness is obtained in a total system including the inverter. This approach is useful for a nonlinear plant such as a direct-drive robot arm