Cascade servo control for LOS stabilization of opto-electronic tracking platform—design and self-tuning

A dual speed loop cascade control structure using the DC tachometer motor to constitute the inner speed loop, and using the rate gyro to constitute the outer stabilized loop is presented since there is shortcome in single speed loop servo control composed of rate gyro for LOS stabilization in opto-electronic tracking platform system. The functions of reducing inner friction disturbance and bating carrier turbulence are designed respectively. The aspects of the system performance and robustness are analyzed and compared with single speed loop control structure in detail. The inner speed loop adopts PI tuner to overcome the influence of nonlinearities caused by friction and mechanical resonances and a time optimal self-tuning PID control algorithm is developed to bate the carrier disturbance in outer stabilized loop. The proposed control structure and scheme based on DSP have been realized in a four-axis opto-electronic stabilized tracking platform. Experimental results can achieve higher stabilized precision and perfect control performance. The proposed control structure and method is effective and practicable in real practical applications.