| Legged robot has a strong ability to adapt to the environment in the process of walking because of only need discrete support points,and has broad application prospects in the field of exploration and military action,even can engage in dangerous work instead of human.Hydraulic drive has the advantages of large power density,quick response,strong anti-interference ability,and large shock and overload,It can satisfy the demandes of legged robot in load,power and dynamic performance.When the legged robot interacts with the ground for an instant,the impact force will affect the stability of robot motion,serious damage to the robot body and key components.Therefore,it is urgent to realize the compliant control of robot.However,only active or passive compliance can not simulate the flexibility,adaptability and impact resistance of human or other animal,Therefore,it is great significance to study the method of combining the active compliance control of the hydraulic servo unit with the passive compliance of the series elastic actuator(SEA,Series,elastic,actuator).In this paper,the core of the study is the compliance control of single joint,Research around with design the single joint experimental platform based on SEA and hydraulic drive unit,analysis force servo characteristics of the system,build the impedance control model of force control based on single joint.On the basis of the structure of series elastic actuator(SEA),combine with hydraulic drive unit,design a single joint experimental platform,and verify the rationality of the structure.analyzes the model of valve controlled asymmetric hydraulic cylinder;Use the pressure sensor to measure the friction force of the hydraulic drive unit and compensate for it,establish the mathematical model of force servo system of hydraulic drive unit and series elastic element,and the Simulink simulation model of the system.By analyze the control strategy of impedance control,build the impedance control model of force control based on single joint,and establish its Simulink simulation block diagram;On the basis of QNX system,PC104 embedded system as the core,set up the control system platform,give the software architecture of its control program,propose the specific algorithm of impedance control,and draw program flow chart of its.In order to study the impedance control characteristics of the single joint experimental platform,build the platform of double cylinder alignment,establish the impedance control model and its Simulink simulation block diagram,and put forward the control algorithm and specific realization of impedance control.On this basis,carried out the experiment of the impedance control on the single joint experiment platform,The results show that the single joint structure and control algorithm are reasonable. |
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