Research On Hybrid Force Control Strategy Of Weld Defect Autonomous Grinding Robot Based On Six-dimensional Force Perception

Along with the rapid development of artificial intelligence technology in China,it has accelerated the reform of intelligent production in China.At present,industrial robots have gradually replaced production workers and are widely used in various grinding and polishing industries.The use of robots for grinding work not only improves the grinding quality of the workpiece,but also greatly increases the efficiency of grinding.However,the grinding and polishing of weld defects after metal welding is still dominated by manual polishing due to the complexity of the surface and the need to keep the grinding contact force constant while removing excess material to avoid damage to the workpiece,which requires high grinding and polishing precision.The problems of manual grinding include low efficiency,poor workpiece consistency,high intensity and poor working environment,which affects the physical and mental health of workers,so there is an urgent need for industrial robots to replace production workers to complete the grinding and polishing of metal weld defects.In this paper,we develop a six-dimensional force perception-based autonomous grinding system to polish weld defects.The main research elements of the paper are as follows.Firstly,the polishable weld surface defects appearing in the welding process are introduced,the overall planning of the robot automatic grinding system is proposed,and a multi-directional force analysis of the grinding process is carried out to establish a weld defect material removal model and complete the robot kinematic modelling.Secondly,gravity compensation calculations are completed for the sixdimensional force sensor so that the sensor can collect real-time polished contact forces.On the premise of force sensing information and force analysis,different contact force compensation strategies are proposed for contact forces in different directions.Namely,in the normal direction,which mainly affects the sanding quality,the force compensation is carried out by means of main force control;in the horizontal feed direction,the impedance control algorithm is used to control the robot’s position,thus indirectly completing the control of the force in the robot’s feed direction;in the direction of the lateral force,where the high speed rotation of the grinding wheel and the unbalanceable motor torque bring about the trajectory deflection,will cause the sanding trajectory to be shifted,and in this direction The focus is on the compensation of the trajectory.And on this basis a hybrid controller is designed for frequent switching of the control algorithm and thus for constant control of the output force of the sanding process.The robot’s autonomous grinding trajectory is then investigated,using a genetic algorithm to find the shortest path for the robot from the start point to the target point,after which the trajectory of the robot’s grinding process is optimised using the proposed3-5-3 segmented polynomial interpolation.Finally,the experimental platform of the robot grinding and polishing system is set up,and the surface defects of the polishable welds are subjected to grinding experiments,while the contact force information fed back by the sensors is recorded by the host computer,and different experiments are set up to compare the contact force information of the grinding process and test the effectiveness of the designed robot autonomous grinding hybrid force control strategy.