INTELLIGENT ACTUATORS - WAYS TO AUTONOMOUS ACTUATING SYSTEMS

The integration of microelectronics within the actuator allows not only replacement of the analog position controller but addition of several functions which give the actuator more intelligent functions. The actuator control is performed in different levels and includes adaptive nonlinear control, optimization of speed and precision, supervision and fault diagnosis. The actuator knowledge base comprises actuator models based on parameter estimation, controller design and a storage of the learned behavior. An inference mechanism makes decisions for control and fault diagnosis, and a communication module operates internally and externally. After a short review of important actuator principles and their properties, as examples, electromagnetic and pneumatic actuators are considered and it is shown how the control can be improved considerably by model-based nonlinear control, taking into account time varying nonlinear characteristics and hysteresis effects. Supervision with fault detection indicates faults in the electrical and mechanical subsystems of the actuator. Several experimental results are shown including the implementation on a low-cost microcontroller.