Digital position control of synchronous motors using an optimal state feedback structure

A dynamic observer of the load torque yielding a good estimation of the load is derived from a simple model. Using such an adaptive device allows the control of a given synchronous servomotor with characteristics that do no more depend on the load torque. Thus, the mechanical mode could be linearized, and a control law that provides excellent performance, particularly in applications where the load changes significantly (such as in robotics), was implemented