Design Of Vertical Compensation Control System For Air-floatation Platform With Six Degrees Of Freedom

With the advancement of science and technology,the demand for exploration of outer space has become stronger and more urgent.As the space exploration tool,spacecraft has played an indispensable role in the exploration process.The tasks in space are more tedious and t he space environment is complex which propose strict requirements on the design and development of spacecraft.Therefore,it is particularly important and necessary to carry out spacecraft test experiments on the ground.The six degrees of freedom air-floatation platform simulation system test is one of them.The six degrees of freedom air-floation platform simulation system includes an orbiter and a riser,which can fully simulates the on-orbit rendezvous and docking process of the spacecraft,thereby effectively reducing the testing cost and further optimizing the performance of the mission.In order to make the process of rendezvous and docking more stable and rapid,this article will conduct in-depth research on the vertical compensation control system o f the orbiter and the center-of-mass stability control system of the upper platform.First of all,for the vertical air bearing,the process of vertical control of the entire operation is analyzed,and the effects of various influencing factors such as film resistance,electrical proportional valves,etc.on the vertical control system are comprehensively considered,and a component-level modeling method is used.The model of each part is established and the hysteresis factor is taken into account.Combined with the overall stress,the pressure control system model and the vertical displacement control system model are obtained.The simulation verify the feasibility of the system model.Secondly,for the cascaded control system where the internal pressure lo op has a hysteresis loop,Smith predictive control is used to perform compensation control.The outer ring first adopts a digital incremental PID controller,and the inner loop adopts a Smith predictive controller to perform preliminary compensation and control on the lag link.For the mismatch condition of the model,an improved Smith predictor based on the principle of super-stability is improved.Then,combined with the requirements of real-time control,a compound controller based on the improved fuzzy controller and PID controller is designed as the controller of the outer loop.The effect of the entire compensation control is optimized,and then different control schemes are compared and verified by simulation.Thirdly,the working principle and proces s of the center-of-mass stability control system on the attitude of the orbiter are studied and analyzed.Combined with the modeling method of Rodriguez parameters,a centroid control system model of the upper platform is established.According to the requ irement of anti-jamming and fast stabilization,a fast non-singular terminal sliding mode controller is designed and its performance is compared with that of PID controller.The simulation compares the effects of the two control algorithms.Finally,the hardware system of vertical compensation control system and center of mass stability control system is selected and the software and hardware systems are built.Design human-computer interaction interface,write control program and carry out engineering experiment test on the proposed control scheme.