Dynamical Analysis and System Identification of the Gantry-Tau Parallel Manipulator

Abstract: This report presents work done in the field of linear and nonlinear system identification on robots. The subject of study has been a new parallel manipulator called Gantry-Tau. The work shall be seen as one of the first steps in the dynamical analysis of the robot. All practical work presented in the report was conducted on a prototype situated at University of Queensland. The actuators have been analysed and modelled with the aim to gain knowledge of weaknesses and dynamical behaviour. The analysis resulted in a study of nonlinear grey-box identification of hysteresis in the drive train of the actuators. A very compact nonlinear hysteresis model was used together with a three-step identification procedure. The results show that a model of the nonlinear system can be successfully identified from measurement data. Finally a method for estimation of parameters in the model for the inverse dynamics of the leg structure has been investigated. It turns out that the investigated method is not able to give accurate estimates. This is thought to be a result of unmodelled behaviour in the system and noisy data.