Abstract
In the article, a heavy-duty quadruped robot was designed. A parallel cylinder transmission scheme for the heavy load torque of the hip joint of heavy-duty hydraulic quadruped robot is proposed, the mathematical model of the parallel cylinder system is derived, the model characteristics of the parallel cylinder system are analyzed, the characteristics of internal force and joint control of parallel cylinders are considered, the force/position hybrid control of parallel cylinder is proposed to eliminate the internal forces and realize the requirement of joint control and the force/position control is decoupled by the design of the force and position signal. According to the characteristics of the servo cylinder force control model, the flow compensation and speed compensation are introduced, the minimum control synthesis controller is used to control the servo cylinder force and the proportional integral controller is applied to control the position of servo cylinder. The compound control strategy is analyzed on the table of parallel cylinder, and the experimental results show that the amplitude attenuation and phase lag of position and force are less than 10% and 18°, respectively, and the efficiency of the proposed control strategy is verified. The research results of this article will be widely used in many fields of robot control in the future.
Highlights
Most electro-hydraulic servo actuators have been used as driving units of hydraulic quadruped robot, which have the characteristics of large driving force, high power density and compact structure
Hydraulic quadruped robots have been studied in Shandong University, Beijing Institute of Technology, Harbin University of Technology and National Defense University of Science and Technology.[5,6,7]
According to the characteristics of parallel cylinder system, the decouple of force/position control was realized by designing the force signal and position signal
Summary
Most electro-hydraulic servo actuators have been used as driving units of hydraulic quadruped robot, which have the characteristics of large driving force, high power density and compact structure. The diagram, the cylinder bottom of another hydraulic cylinder A0 cannot be located in the sector area composed of CBC0 and DBE when the driving mode is double cylinder At this point, the drives joint of piston rod have a dead center, and the desired motion cannot be achieved. The form of figure (f) can guarantee the same driving force of roll joint in the positive and negative directions, and it is an ideal choice. Roll joints are driven by two electro-hydraulic servo actuators to increase the joint drive torque. According to the equivalent principle of the load, the equivalent model of the electro-hydraulic servo actuator is obtained, as shown, where m 1⁄4 J L=L2, KL 1⁄4 KL1=L2, FL 1⁄4 T L=L and L is the distance between the roll shaft and joint bearing of actuator piston rod. Equation (2) can be expressed as equation (3) for cylinders 1 and 2 f 1 1⁄4 Ca1V ðsÞu1 À Ca1y1s y2
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