The Application Of Parallel Leg Mechanisims In Quadruped/Biped Reconfigurable Walking Robot

Walking machine can walk steadily on uneven terrain, avoid the obstacle, climb stairs and trudge swamp. As a result, it can be applied to the load running and the life assistive walking. At present, the legs of walking robot are mostly based on the series leg mechanisms. A quadruped/biped reconfigurable walking robot based on PM (parallel mechanism) used for the elderly and disabled people is introduced in this paper. The advantages of the walking robot based on PM are analyzed. The kinematics model of the parallel leg mechanisms and the quadruped/biped reconfigurable walking robot are investigated. The results affirm the application of the lower-mobility parallel mechanisms in the walking robot. This research provides a theoretical basis for the further investigate of the walking robot with quadruped/biped reconfigurable parallel leg mechanisms.Firstly, the paper researches the development status of the walking robot technology, analyzes the motion characteristics of the walking robots and its leg mechanism. The 3-UPU parallel mechanism with three DOF (degrees of freedom) is analyzed, and the application of the parallel mechanisms in the reconfigurable quadruped/biped walking robot is discussed.Secondly, the paper proposes the 6-SPU PM made by two 3-SPU PM to act as the biped walking robot legs based on the geometric properties and kinematics characteristics of the 3-SPU PM. It also makes the kinematics analysis of three typical 6-SPU PMs.Next,the kinematics modeling methods, the DOF of the robot, the inverse displacement and inverse velocity and acceleration of the quadruped/biped robot are investigated.Then, according to a typical crawling gait, the static stability analysis of the quadruped walking is analyzed. The minimum and the maximum static stability area (SSA) which was caused by the offset of the center of gravity in the process of static stability are defined. And the general ways to increase the static stability area (SSA) are proposed.Finally, a virtual prototype of a quadruped/biped walking robot with parallel leg mechanism is built in PRO/E. The displacement curves of drive rods, the velocity and acceleration curves when two terminal trails are obtained. And the kinematics simulations are shown with the software of ADAMS.