Research On Compliance Peg-in-hole Assembly Technology Of Industrial Robot

Robot assembly is the last step to realize automated production.It is very important to ensure the immobility and accuracy of assembly process.Traditional industrial robots are mostly used for position control.Aiming at the specific application of assembly operation,whether the contact force can be well-controlled is the most important factor to ensure the success of assembly.Aiming at the typical shaft hole assembly problems,a control strategy is put forward in this thesis to realize the peg-in-hole assembly task of industrial robot with the six dimensional force sensor,and build a high-precision peg-in-hole assembly experimental platform,which verifies the feasibility of the control system through tests and experiments.Firstly,the kinematics model of SR4 C industrial robot is established through DH parameter model.In view of the structural characteristics of SR4 C industrial robot,this thesis analyzes the solution of inverse kinematics,and finishes the mutual transformation from Cartesian space to joint space.Secondly,the compliant assembly method of industrial robot is studied.The assembly process is divided into three stages,the forces and adjust mode is analyzed.Then,an admittance controller is designed to establish the relationship between contact force and position,and the improved selection matrix is used to realize the mutual switch between position control and force control,which makes the control mode switch process smoother.In addition,to solve the problems of offset and to reduce the data noise collected by the six-dimensional force sensor,a gravity compensation algorithm was proposed to compensate the offset,and Kalman filter was used to filter the data noise.Then,the soft framework of the control system of assembly is built.The force data acquisition module and visual positioning module are developed as a software.The communication program among robot controller,force sensor,industrial camera,teaching pendant is written to realize the data transmission among every module.The human-machine interaction interface of industrial robot are developed based on Qt integrated development environment.Finally,the experiment platform of peg-in-hole assembly was built,including industrial robot,pneumatic gripper,industrial camera and teaching pendant.The visual positioning function and peg-in-hole assembly function were tested respectively,and the experimental verification was finished for three different fitting clearance.Experimental results show that different fitting clearance will lead to differences in assembly time and contact force.However,industrial robot can complete the peg-inhole assembly task,which verifies the feasibility of the compliance assembly strategy in this thesis.