| By far wheeled robots and tracked robots are technically mature and extensively adopted, however, they are constrained to move on even terrains. Over half of the land surfaces are rugged mountains, jungles, and lands covered by snow and ice. In nature, many kinds of animals, especially the four-legged mammals, not only can walk on these complex terrains rapidly, but also have large load capacity. As a result, humans have been trying to manufacture a wide variety of quadruped bionic robots. In recent years, hydraulic-driven quadruped bionic robot, possessed of high dynamic ability and large load capacity, is brought to the attention of more and more people.Although numerous quadruped bionic robots have been produced, bionic structure design, power drive system, dynamic modeling, locomotion control methods and other various aspects, have not formed any mature theory systems, and still remain explored. In this paper, the bionic structure design of the hydraulic driven quadruped bionic robot, the planning of foot trajectory, kinematics analysis, dynamics simulation, the design and realization of onboard hydraulic power system, and the integration and experiment validation of the experimental prototype have been performed. The main content is as follows:(1) Based on the analysis and research about the bone structure and motion pattern of typical four-legged mammals, a hydraulic driving mechanism with12active DOFs, which equipped with front and rear symmetrical motion and omni-direction motion ability and rapid walking ability has been designed. Based on the simulation results of the co-simulation model established in ADAMS/MATLAB, each joint’s moving range, moving velocity and joint driving force and other important parameters were obtained. The optimization and perfection of the bionic structure of the quadruped robot were accomplished, on the basis of which highly dynamic and highly integrated hydraulic power unit whas been designed.(2) A composite foot trajectory planning method was proposed in this paper, which greatly decreased the impact forces between swing feet and ground at the touchdown moment and enabled the robot move more steadily. A numerical analysis was carried out for SCalf based on D-H kinematics model. The variation curves of joints angles, joints angular velocities, joints angular accelerations, cylinder displacements, cylinder velocities, cylinder accelerations were given from the analysis results. Subsequently, another numerical analysis was carried out for SCalf based on a computer aided kinematics analysis method which has good real-time quality. The results were identical to those of numerical analysis based on D-H kinematics model.(3) Many important parameters such as impact forces between robot feet and ground, driving forces of each hydraulic servo cylinder, the velocity and acceleration undulations of torso were gained from the kinematics and dynamics simulations under ADAMS by both off-line planning with spline driving and co-simulating with MATLAB.(4) High power/mass ratio, highly compact and quake-proof onboard hydraulic power system were designed and implemented with a positive pressure closed hydraulic circuit made up of miniature variable oil tank and high speed plunger pump and twelve asymmetric hydraulic servo cylinders, which solved the power problem for SCalf robot to walk on the field.(5) A hydraulically actuated quadruped robot with twelve active DOFs and four passive DOFs is integrated. The experiments of load capacity, uneven terrains adaptability, resistance to lateral impact, maximum speed, uphill, downhill, endurance were done to test the comprehensive performance of it. The experimental results proved its high dynamic ability, large load capacity and international advanced technical indicators.The hydraulically actuated quadruped robot developed in the thesis had passed the on-site test and evaluation organized by the National I ligh-Tech Development Management Center on January16,2013. The conclusion is that the research task has been done excellently. |
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