Control system design of multi-gimbal Electro-Optical platform by the technique of μ-synthesis

To extend target tracking range, configuration of two-axis four-gimbal is used for high precision Electro-Optical stabilized platform, but coupling among gimbals and complexity of system are augmented. The significant target of control system design is to improve the stabilized performance of optical sensors´ line-of-sight. Based on dynamic equations of the platform system, state space model is derived. Because of coupling characteristic, the inner gimbal subsystem and the outer gimbal subsystem are regarded as a multi-input multi-output plant so that multivariable control is employed. With parameter variation considered as perturbation, which is associated with elevation channel coupling information, a controller for azimuth channel based on μ-synthesis is designed according to respective performance specification of stabilizing and angle position servo. Simulations show that the system has achieved robust performance with changing of elevation working conditions, and that under the circumstances of ensuring appropriate servo precision, there is improvement in evidence about stabilizing performance comparing with system using decoupling controllers for inner gimbal subsystem and outer. Owing to multivariable μ-synthesis control method, system performance is improved effectively.