Research On Control Of Cable Driven Deep Squat Training Robot

Nowadays with the development of technology,there is a vigorous development in manned space flight that human being have been making a footstep to space gradually.However,the health of astronaut is threatened by the major space negative factor—microgravity.To address the single function and the unsatisfactory training effect of the current rehabilitation training equipments for astronauts,a cable-driven deep squat training robot based on the feature that the parallel cable-driven robot can simulate gravity is proposed.The robot can load the force on human body and assist astronaut to realize deep squat training to alleviate the adverse impact caused by the adaptation space syndrome.To ensure effectively load of the robot,the theoretical and experimental analysis of overall scheme of structure,flexible cable-driven unit and man-machine control strategy are conducted,the specific research contents are as follows:By analyzing the hazard of adaptation space syndrome,the mechanism of deep squat training can be obtained and the design requirements of robot are also explicit.Therefore,the system overall scheme of structure and controller can be designed according to requirements.The single flexible cable force servo controller which is applied to control system can be developed based on structure invariance principle.The model of forward kinematic and inverse kinematic are established by taking human lower extremity as the study object.The angle variation law of knee joint and ankle joint are studied by the simulation of deep squat.At the same time,the dynamic model of human lower extremity is also established and the mechanical properties of joints are studied by simulation.Then the model and traction force planning of flexible cable are carried out.Through the simulation,the mathematics relationship between the expected loading force,the tension and length of each cable during the deep squat can be revealed.The active force servo control strategy of single flexible cable is proposed according to its servo drive model.The precision and rapidity of the strategy are evaluated by simulation.The passive force servo control strategy is designed to ensure the robustness of the system and the effect of eliminating the surplus force is validated by simulation.A quasi closed loop control strategy of flexible cable-driven deep squat training robot is carried out.The effectiveload of each flexible cable-drive unit are ensured by inner loop—single flexible cable passive force servo controller,the desired force of each flexible cable are calculated by the longitudinal traction force planning model,the influence of transverse force is real time eliminated by the compensation planning strategy,so the loading precision of the system can be improved.The model of man-machine system is built by using MATLAB/Simulink toolbox and the effectiveness of the passive loading of the quasi closed loop control strategy is verified by simulation.The single flexible cable servo control experiment,double flexible cable servo control experiment and man-machine system experiment are conducted,respectively,through arranging the flexible cable-driven units into different prototype configuration.The configuration rationality of the flexible cable-driven deep squat training robot and the effectiveness of the control system are further verified through the experiment.The experiment results show that the flexible cable-driven deep squat training robot can assist the astronauts to carry out deep squat training during space trip.