Mechanism Analysis And Trotting Stability’s Gait Planning Of Hydraulic Quadruped Robot

Quadruped robots have abilities of high load, good stability, great mobility and adaptabilitywhich advantage wheeled robots seldom possess. In the future, quadruped robots are expected to beemployed for a variety of dangerous and dirty tasks in fields like search and rescue, humanitariandemining etc. This thesis makes a research on a hydraulic qaudruped robot, deeply analyses itsmechanism, kinematics, dynamics and hydrautic system. Based on stability theory of trotting gait,elliptical leg-trajectory was planned, and such work was completed as below:1. Robot’s mechanical feature and its foward and inverse kinematics were analysed, and acomposite cycloidal leg-trajectory was planned. Combining with trotting gait’s trajectory planning,robot’s stability was analysed in ADAMS.2. Dynamic model of single leg was established based on lagrangian dynamics, verified inADAMS, and simplified properly. Besides, joint internal force of single leg was deduced, calculatedand verified, so as to provide important mechanical basis for body’s mechanical analysis and dynamicstability research of robots. At last, hydraulic cylinder’s mechanical analysis was deduced to help dodeep study on hydrautic mechanism of the robot.3. Hydraulic oil-line system and foot’s work space of the robot are analysed. Combining withmovement speed’s design objective of the robot, relevant gait parameters are designed, and then fluxwhich the oil hydraulic pump needs in theory was calculated. Further more, gait parameters’ impacton the flux was analysed. All work in this part helps to improve robot’s structure and select oil pump.4. Combining with virtual leg principle, linear inverted pendulum model (LIPM) and zeromoment point (ZMP), based on trotting gait with duty cycle of0.5, quadruped support phase wasadded reasonably in the motion transition stage, and trotting gait trajectory was planned. Duringstance phase, smooth ZMP trajectory was used to deduce robot’s COM trajectory, so as to obtain foottrajectoty of the stance phase. And during swing phase, in order to ensure the consecutiveness andsmoothness of location and velocity, ellipse and cubic polynomial are combined to plan foot trajectoryof the swing phase. At last, the rationality of new gait was verified in ADAMS. As a result, thestability of qraudruped robots is enhanced to a great extent from the perspective of gait planning.