Modeling and Control of High Speed Mechanisms Using Inverse Dynamic Analysis

Abstract

Inverse dynamic analysis can be used in designing controllers, but the computational requirements may prevent its use in real time. A combined piecewise linearization and off-line inverse dynamic analysis approach has been exploited in this paper to achieve the required computational efficiency with the convenience of traditional linear controllers, coupled with the accuracy and adaptability of inverse dynamic analysis. The paper simulates a three-degree-of-freedom RRR planar mechanism to demonstrate the techniques. An inverse dynamic analysis of this mechanism is carried out for different desired motions and for different operating speeds. A piecewise linearization approach is introduced to represent the system as a multi-input multi-output linear system with motion and speed dependent coefficients. A separate linearization method is developed to determine the error dynamics off-line. A standard linear-quadratic regulator is applied to the linearized model for the design of a feedback controller. The robustness against external disturbances of the proposed adaptive linearized feed-forward and feedback controller is examined by simulated examples. Most of the computationally demanding inverse dynamic and linearization calculations are carried out off-line, therefore the technique offers many potential applications involving highly complex systems.