Compensating the Influence of Backlash in Highly Rigid Kinematic Transmission of Electromechanical Tracking Systems

The existing methods of compensating the influence of backlash in electric drive tracking systems, implementing contour-positioning control of production machine loads, were analyzed. Their advantages and disadvantages for controlling single-channel electric drives have been identified. Based on correct application of the describing function method for linearization of nonlinearity, detailed analysis was performed of a standard astatic tracking system for electric drive with cascade control of current, speed and position. The causes of automatic oscillation and deteriorated quality of transient processes in electric drive with backlash in its mechanical section have been revealed. As a result of frequency analysis of the dynamics of a nonlinear electric drive system, we have developed complementary methods of compensating the influence of backlash by correcting the properties of integrating elements in the main position control loop given abrupt changes in kinematics. These methods are implemented by using a PI position controller with a switchable integral part, and by introducing additional stabilizing feedback for angular displacement difference of the electric motor and operating unit at current controller input. The effectiveness of the results of our theoretical research is confirmed by detailed mathematical simulation of the developed electric drive control systems, and also by in situ experiments on a multifunctional test bench.