As a typical bionic walking robot, hydraulic quadruped robot has attracted much attention because of its high mobility, strong load capacity and steady motion. The electro-hydraulic servo cylinder, as its power actuator, requires low friction, good lateral load resistance and high speed motion. The electro-hydraulic servo cylinder hydrostatic bearing seal guide sleeve is taken as the research object in this paper. By using Fluent software to analyze and contrast the film characteristics of rectangular and I-shaped oil chamber of hydrostatic bearing seal guide sleeve, the relationship between piston rod moving speed, eccentricity, oil film carrying capacity, friction force and leakage volume, as well as the relationship between oil feed flow and oil film bearing capacity, friction force, inlet pressure and leakage volume were analyzed. This study provides a theoretical basis for optimizing the static pressure bearing seal parameters.
A prototype of hydraulically powered quadruped robot is presented.The aim of the research is to develop a versatile robot platform which could travel fleetly in outdoor terrain with long time of endurance and high load carrying ability.The current version is 1.1m long and 0.48 m wide,and weights about 150 kg.Each leg has four rotational joints driven by hydraulic cylinders and one passive translational joint with spring.The torso carries the control system and the power system.A novel control algorithm is developed based on a Spring-Loaded Inverted Pendulum model and the principle of joint function separation.The robot can not only cross a 150 mm high obstacle in static gait and trot at 2.5km/h and lkm/h on the level-ground and 10°sloped-terrain respectively,but also automatically keep balanced under lateral disturbance.In this paper,the mechanical structure and control systems are also discussed.Simulations and experiments are carried out to validate the design and algorithms.
