Abstract
Disturbance torque and unmodeled dynamics are the main important factors which affect the angular velocity precision of a gimbal system in double gimbal control moment gyro (DGCMG). In this paper, a compound control method combining reduced-order cascade extended state observer (RCESO) and integral sliding mode control (SMC) is proposed, aiming at effectively eliminating the influence of exogenous disturbances and unmodeled dynamics, and achieving high precision angular velocity control of the gimbal system. Firstly, the disturbance torque is observed by the RCESO, and the parameter tuning method of RCESO is studied. Secondly, to enhance the robustness of the whole control system and take into account disturbance estimation errors, an integral sliding mode control is introduced. Simulation and experimental results show that the proposed control method not only improves the compensation performance of the gimbal system with external disturbances, but also enhances the robustness and improves the angular velocity precision of the gimbal system.
Highlights
Control moment gyro (CMG) has the advantages of large output torque, good dynamic performance and high control accuracy, making it the preferred actuator of attitude control for large spacecraft [1], [2]
Considering the disturbance estimation errors of the total disturbance and with the aim of achieving total robustness and high precision angular velocity, this paper proposed a compound controller by putting together the design of using sliding surface and reduced-order cascade extended state observer (RCESO)
The traditional cascaded ESO (CESO) can be transformed into a RCESO cascaded by two similar secondorder extended state observer (ESO), which simplifies the model of traditional CESO
Summary
Control moment gyro (CMG) has the advantages of large output torque, good dynamic performance and high control accuracy, making it the preferred actuator of attitude control for large spacecraft [1], [2]. Yu: Anti-Disturbance Control Based on Cascade ESO and SMC for Gimbal System of DGCMG was proposed to compensate the nonlinear friction torque of gimbal system. The theory and parameter configuration method of second-order ESO are relatively mature, and has been successfully applied in many industrial processes [27], [28] To overcome this problem, a cascaded ESO (CESO) where the m+1 order ESO is replaced by m similar cascaded second-order ESOs with the same parameters was used to improve the accuracy of gimbal angular velocity [29]. A reduced order CESO (RCESO) which is cascaded by two similar second-order ESOs is designed to estimate the unknown uncertainties and exogenous disturbances, and the parameter configuration method are given through frequency domain analysis.
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