High performance control of a transmission based servo actuator system

High performance actuation is a key factor in the industrial robot area. The transmission based servo actuator system (TBA) is a new type of robot actuator with a brushless DC servo motor and a three speed discrete variable transmission (DVT).; The TBA is a typical hybrid dynamic system consisting of three continuous dynamic systems and a discrete state controller. This dissertation addresses the fundamental problems associated with the TBA system control from a hybrid system point of view.; A detailed dynamic model of the TBA is developed. The TBA system is simplified into a hybrid system with three second order linear time invariant systems, on which all the controls are developed.; For a hybrid system, the stability problem has much broader range of issues than a purely continuous system. In general, the plant stability and the subsystem stability are independent. In this dissertation, a sufficient condition is established for stability of the TBA system. It is proven that the TBA system is stable under asynchronous switching because a common Lyapunov function can be found by using state feedback. The feedback controller to stabilize the TBA can be transformed into a PID equivalent controller because the subsystems are second order linear time invariant systems (LTI). The PID controller was then implemented and high performance in terms of position error and transient suppression has been achieved.; The discrete state controller should be stable, which means that its output should be consistent if the hybrid system is subjected to disturbances. This research proposes a switch strategy consisting of two boundaries to achieve the transition stability, and it is proved that the proposed switch strategy is transition stable.; Based on the proposed control methods, a multithread real time control software has been developed to achieve a deterministic control loop sampling. The control software is developed in C/C++ under Real Time Application Interface (RTAI), which provides a real time programming environment in a normal Linux operating system.