The Control Research Of Suspended Low-gravity Simulation System

With the vigorous development of aerospace,simulation and verification of experimental equipment on the ground are researched widely.In order to simulate the space or the gravitational environment of the other planets,a low-gravity simulation system is needed.At present,most of the gravity environment simulation system use the way of suspension,which utilize the weight or spring to balance the gravity,this approach is generally applicable to low-speed moving objects and difficult to apply to the vertical separation of the planet’s surface.In this paper,an active suspended low-gravity simulation method is proposed.A series of measures,including hardware and software,are proposed to improve the response speed and simulation precision of the system.The experimental platform of low-gravity simulation system is completed and verified.The control algorithm of the system is designed from the aspects of classical control and modern control.The realization scheme of the whole suspended low-gravity simulation system is put forward according to the required performance index.By adding the buffer spring,increasing the rigidity of the rope and the length of the suspension to improve the response speed and simulation precision,at the same time,take the force control and speed control in two ways to improve the response speed by utilizing the stall operation mode torque motor.The mechanical structure and the comprehensive control system are designed and the experimental platform is built.The control scheme of hardware and software are established and determine port’s connection method of the measurement and the control amount.The control model of torque motor and the nominal model of the system are established according to the experimental platform.The resonant frequency of the electromechanical servo system and the buffer mechanism are analyzed,which provide a reference for the designing of the controller.In order to control the system effectively,the control algorithm is designed by the classical control theory.The basic control model of the system is established,and the reasonable transition process is arranged for the input signal.The static and dynamic equilibrium of the system are established by Z-N setting PID control and the system’s correction,at the same time,the static equilibrium error experiment is carried out to analyze the system The vertical motion of the target object is equivalent to the external disturbance of the system and the feedforward compensation based on structural invariant and the establishment of perturbation observer disturbance strategy are simulated and verified.In order to make the system adaptable,a selfadaptive fuzzy PID control method is proposed,and the linguistic variable,the membership function and the fuzzy rule are established,and the fuzzy controller adapted to the system is obtained.In order to solve the uncertainties of the system and the external position disturbance,it is proposed to use H∞ robust control to obtain the controller by means of analytic method.The uncertainty of the system is analyzed and processed,and the weighting function is determined by the small gain theorem into the H∞ standard design problem.The generalized control object is obtained and the controller is calculated.The controller is reduced by Hankel approximation in order to increase physical availability.The Simulink is used to simulate the controller performance and compared the original controller to the reduction.