Research On The Robotic Force And Position Hybrid Control Grinding System For Rails

With the rapid development of China's economy,China's production is becoming more and more scientific and modern.In recent decades,the rapid development of railway,and rail as the foundation of the railway industry,its processing quality has higher requirements.The welding line grinding of rail is a key point in the development of high-speed railway.With the rapid development of industrial automation in recent decades,it has become an inevitable trend to automate the grinding of rail welding seams.In the process of automatic grinding of rail welding seam by robot,common position control will cause stuck problem when grinding the surface of complex rail welding seam because of the bump of welding seam.In order to strengthen the quality of automatic grinding,it is necessary to add force control to robot control.Based on the characteristics of industrial robots,this paper analyzes the force/bit hybrid control scheme of the grinding robot,realizes the constant force grinding of the grinding robot in the process of grinding,and improves the grinding quality of the grinding robot.Relevant research work includes:(1)The kinematics model of grinding robot is established.Firstly,the kinematics description of the robot is introduced,and the coordinate system of each link is established for the grinding robot of this project,and the forward and inverse kinematics are solved.In the feedback control link of force control,the position of the tool end needs to be adjusted to achieve the effect of force compensation,and the realization of the position will be decomposed to each joint through the kinematics.(2)The force/bit hybrid control scheme is studied.Through the research and understanding of the current control methods,combined with the actual situation of grinding,the joint control method of position ring based compliant control and speed ring based force/bit hybrid control is proposed.The stability of the control system is analyzed,the gravity compensation of the six-dimensional force sensor is given,and the coordinate calibration of the six-dimensional force sensor is analyzed.(3)Simulation and experiment of force/bit hybrid control system.The control system of the grinding robot is simulated and analyzed in MATLAB,including the step performance and tracking performance of the control system.In addition,the verification experiment of the control system is established to solve the control parameters required by the control system.The practicability of the control system is analyzed through the experiment.The experiment proves that the system has the effect of force/bit hybrid control and can make the direction requiring force control realize constant force contact.