ADAPTIVE SERVOMOTOR CONTROLLER

The gain of a servomotor driven process control system is adaptively compensated for changes in the motor coulomb friction torque. The gain is manually adjusted at the time of installation. Thereafter, the minimum motor current occurring in a process cycle is identified, and the gain is automatically adjusted if the identified minimum motor current changes over time, indicating a change in the motor coulomb friction torque. As a result, the level of response stability achieved at the time of installation is maintained despite changes in the motor coulomb friction torque.