Study On The Variable Stiffness Cable Driven Joint Modules

Cable driven robots have the advantages of light weight,small moment of inertia and good security and get widespread attention in the field of service robots.However,the stiffness of the traditional cable driven robots can't be adjusted and controlled which restricts the further improvement of the security.In order to significantly improve the motion flexibility and operation safety of cable driven robots,this thesis focuses systematically and deeply on the study of the core components:variable stiffness cable driven joint modules,of the modular cable driven variable stiffness robot arm.The main research content is as follows:(1)Design of the Variable Stiffness Device:The variable stiffness device is the key of the cable driven joint modules to achieve a wide range of stiffness adjustment.Based on the design theory and method of the flexible parallel mechanism,this thesis comprehensively analysised the configuration and structure of the variable stiffness flexible parallel mechanism.After the optimization design,three kinds of variable stiffness devices were proposed.They had simple and compact structure,large stiffness variation range and highly linear stiffness;(2)Design of the Single DOF Cable Driven Variable Stiffness Joint Module: Based on the stiffness model of the variable stiffness device,this thesis presented the stiffness analysis method of the single DOF cable driven joint module and optimized the joint module.After optimization,two kinds of the single DOF cable driven variable stiffness joint modules,which had larger variation range of stiffness,were got.(3)Design of the 2 DOF Cable Driven Variable Stiffness Joint Module: Based on the stiffness model of the variable stiffness device,this thesis presented the stiffness analysis method of the two DOF cable driven jointmodule.According to the proposed method,the joint module using 4 vairable stiffness devices was optimized.After optimization,the two DOF cable driven varaible stiffness joint module,which had larger variation range of stiffness,was got.(4)The Building of the Performance Test Platform: Based on the test requirements of the variable stiffness cable driven joint modules,this thesis designed and built a performance test platform for the cable driven joint modules,which can conveniently perform motion control and stiffness performance test of the cable driven joint modules.Through utilizing the redundant drive characteristic of the cable driven mechanisms,the proposed variable stiffness cable driven joint modules can achieve variable stiffness control by optimizing the tension distribution and further realize the intrinsically safe compliant motion like human arms.