ADRC Inverse Compensation for Mechatronic Systems with Output Backlash & Single Encoder

The Backlash non-linearity limits the dynamic performance and the precision of control systems in positioning tasks, especially in systems equipped with a single encoder installed before the backlash mechanism. To deal with this problem, this article proposes two different schemes to compensate for backlash effects in a system with output-backlash and a single encoder. First, a mechatronic system model with backlash is presented. Then, a parameter estimation method is presented to obtain accurate parameters of the backlash model. Later, an Active Disturbance Rejection Controller (ADRC) is designed and applied in order to evaluate: a) two backlash compensation schemes, and b) two backlash inverse models. A set of tests with different backlash angles and backlash uncertainties are proposed to assess the performance of the controller and the backlash compensation schemes. Finally, simulation results and problems evidenced are presented.