Several Fundamental Theroy Research On The Bionics Design Of Humanoid Robot Hip Joint Based On Spherical Parallel Mechanism

With the advancement of contemporary mechanisms developing towards intelligent, high precision, higher-speed, highly reliability and highly integrated etc, and due to the excellent advantages, parallel mechanisms shows, such as compact structure, higher stiffness, superior kinetic characteristics and strong bearing capability, continuous researchers’ attentions were put into parallel mechanisms. Seval basic bionic theories of humanoid hip joint were analyzed respectively, basing on a spherical parallel mechanism, and referring to the hip joint structure’s traits and it’s kinetic characteristics. Mainly contents of this paper are as follows:Via studying details of the hip joint’s structure traits, kinetic characteristics and its moving space limits, and basing on the preciple that mechanisms’ structure and its function traits have to be consistent with human’s hip joint’s characteristic, the 3-SPS/S(where S denotes a spherical joint; P denotes a translational pair) spherically parallel mechanism was selected as the bionic prototype.Kinetic analysis of this 3-SPS/S parallel mechanism was completed, then it’s kinetic-inverse solution was built as well; on the base of influence coefficient method, lower-mobility mechanism’s first-order and second-order influence coefficient matrix were deduced respectively, and it’s driving pairs and constraint pairs are not contained in one same limb. Basing on the analysis above, the velocity and acceleration of mechanism were studied, then the deduced equations and analyzing results were demonstrated by simulation software.Orientation workspace and position workspace were drew though the numerical method; when mechanism’s input range, kinetic pairs’ rotation-ability, interferences between different components and other factors were considered comprehensively. Taking the largest workspace of the mechanism as the objective function, the dimension parameters of the bionic joint was optimized via genetic algorithm(GA), then reasonable bionic structure sizes have been obtained.Singular orientations and positions were confirmed via analyzing mechanism’s singularity based on Gosselin method, meanwhile, singular tracks were depicted. Considering its symmetry, other singular tracks were deducted and verified as a supplement, simultaneously, its validity was demonstrated.According to the influence coefficient matrix of mechanism’s first-order and second-order, dynamic analysis for mechanism is processed, considering D’alembert’s principle and principle of virtual work. Then, using ADAMS software, mechanism’s dynamic motions were simulated. Thus under a given track of moving platform, mechanism’s driving force-time curve, spherical joint’s(on the platform) force-time curve and centrically spherical joint’s force-time curve were depicted individually.