Design Approach Research On Lightweight Robotic Arm Based On CFRP/AA Hybrid Structure

Robotic arm is an electromechanical integration device that includes machine,material and control technology in one mechanical equipment,and it has been widely applied in industrial,aerospace and medical services sector.But with the increasing shortage of global energy,the development of traditional robots has been restricted because of large mass and high energy consumption.Lightweight design for robots could improve energy efficiency conforming to the future development demand,which gradually has become research hotspot in lightweight robotic arm domain.Compared with steel,aluminum alloy(AA)and other metal materials used in traditional manipulators,Carbon Fiber Reinforced Plastic(CFRP)has high specific stiffness,high specific strength and outstanding designability,and it is used for designing robots contributing to improving light-weight grade.Taking the immature manufacturing process of composites in contrast with conventional materials,a hybrid structure composed by CFRP and AA parts was designed and applied into body structure of robots;in order to further increase load/weight ratio,the deisgn method for hybrid structure in robotic arm was explored.The specific study content is as follow:Firstly,the design scheme and flow of robot with hybrid structure were confirmed.The configuration of manipulator was selected according to feature of tasks.Then,a comprehensive analysis was carried on for different materials properties,aiming at selecting suitable lightweight materials.Based on the characteristics of configuration,static and dynamic performance of robot,the design plan of links was defined;referring to robotic arm in AA,the joint shells were improved design,and then local modular joints were designed taking joint compactness and task characteristics into account.As for hybrid structures composed by joint shells and links in different materials,its connection plan was determined by material processing technology and connection ways between parts.Base on this,the lightweight design process of robot with hybrid structures was completed.Secondly,optimization model was established and used to calculate.Some relevant dimensions of hybrid structures were parameterized as design variables;that hybrid structures have minimum weight was selected as design objective;and static performances,dynamic properties and connection performance were defined as design constraints.Thus the optimization model was constructed.Taking a 4-DOF robotic arm as optimization example,it was conducted on a platform integrating ABAQUS with modeFRONTIER utilizing GA to achieve the optimal parameter.Combined kinematics and dynamics the joint torque was realized,and through developing USDFLD the progressive damage of upper arm was investigated,which verify the feasibility of design result.Lastly,the prototype was fabricated and tested.The robotic arm with hybrid structures was manufactured based on design results.By static and dynamic tests,the results show the robot could have excellent static and dynamic properties simultaneously.In addition,the tested joint torques was compared with that of a robot in AA to demonstrate the validity of above lightweight design method.Furthermore,the measured joint temperature was in contrast with simulation results to verify the accuracy of finite element model used in heat analysis.