Design, dynamics, and identification of a flexible joint robot manipulator

Joint flexibility limits the performance of an industrial robot by introducing resonant frequencies in the same range of the control band width. If joint flexibility is considered in modelling, advanced control techniques can be designed to achieve a higher performance. This paper describes the design, dynamics, and identification of a two-degree-of-freedom flexible joint robot manipulator. The robot serves as a test bed to formulate and evaluate the performance of control algorithms for position and force control of flexible joints robot manipulators. The development and dynamic characteristics of two different models are presented. In the first model, the links subsystem and the motors subsystem are only statically coupled, whereas in the second model the two subsystems are dynamically and statically coupled. The identification of the robot parameters is reduced to the identification of two transfer functions, one for each motor-link system. A comparison between the computed parameters using a solid modeller and the experimental values is presented. A feedback linearization control algorithm is designed and implemented in the joint space as a means of validating the identification results when using such a model-based controller.