| It is unclear whether the biomechanical mechanism of the formation and treatment of common ankle disease clinically.Therefore,it is urgent to study the mechanical relationship between the components of the ankle,including the relative motion,interaction force,and the time course of the muscle strength of the ankle to complete the normal gait and various complex movements.For the above questions,this paper presents a 6-DOF ankle gait simulator based on electric and liquid hybrid drive and applied to human ankle gait simulation and mechanics measurement.The horizontal drive hydraulic system,as a subsystem of the simulator,is a typical electro-hydraulic proportional position control system with load disturbance during the simulation test of the ankle complex,and its dynamic tracking accuracy and robust performance play a crucial role in the process of gait simulation and mechanical measurement of the ankle complex.Therefore,it is necessary to study the control strategy of electro-hydraulic proportional position control system with load disturbance to improve the test effect of 6-DOF ankle gait simulator.The corresponding research work has been done for 6-DOF ankle gait simulator horizontal drive hydraulic system,and main research work is presented as follows:Firstly,according to the kinematics and kinetic characteristics of the ankle complex,the overall scheme design of the 6-DOF ankle simulator is completed,including horizontal drive hydraulic system,6-DOF platform,tibia loading system and tendon loading system.At the same time,the design ideas and schemes of 6-DOF platform,tibia loading system and tendon loading system are discussed respectively.In particular,the overall design of the horizontal drive hydraulic system and the selection of components are described in detail.Then,the mathematical model of the electro-hydraulic proportional position control system with load disturbance is established by combining basic equations of the hydraulic power component of the electromagnetic proportional directional valve,the hydraulic flow equation and the dynamic balance equation of the hydraulic cylinder.And adaptive robust control strategy is proposed for effects of uncertain parameters and disturbance,such as the oil supply pressure of the accumulator,the inertia force of the 6-DOF platform,the tibia loading and the tendon loading,on the tracking accuracy and robust performance of the ankle gait simulation process.Moreover,methmatical and physical simulation models are established,based on mathematical derivation and physical components,to verify reflection of the design of state space expression on the actual physical model.At last,6-DOF ankle gait simulator experimental platform is set up and control program is completed based on LabVIEW software.On the basis of that,the experimental study on the horizontal driving hydraulic system with load disturbance is carried out.The experimental results show that the robust control strategy has a great effect on the robust performance of the electro-hydraulic proportional position control system and can guarantee the requirements of 6-DOF ankle gait simulator.In comparison,the adaptive robust control strategy improves the tracking accuracy of the system while ensuring the robust performance,and ensures that horizontal drive hydraulic system to stably and accurately cooperate to complete the biomechanical experimental work of ankle complex with different nonlinear load disturbance. |
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