A Unified Approach for Independent Manipulator Joint Acceleration Control and Observation

The ultimate goal of a manipulator control design is to combine the design of both the controller and the observer into one procedural approach. Hence, the stability of the global system, namely, the manipulator dynamics, controller, and observer is guaranteed. This paper presents a new, unified approach in combining the control and observation problem for robotic manipulators. It links the design of an independent joint acceleration controller to the design of a variable structure state observer that is used to estimate the joint acceleration. Since both the joint acceleration controller and the observer introduced in this paper are likely to implement high gains to improve tracking, the effects of the time delay between the measurement of the output and the control loop response has been investigated. The observer design also considers the observation robustness against unknown but bounded disturbances using the theory of variable structure systems. A simulation study to investigate the performance of the joint acceleration controller and observer is conducted on a PUMA 560 robot. Simulation results showed that the proposed combination of observer and controller are robust to the change in the payload and small time delays.