| Maintaining constant force on the workpiece during the robot's automatic polishing of the workpiece helps to improve polishing efficiency and polishing accuracy.For freeform workpieces,in order to maintain constant force during polishing,the end effector must be designed according to the curvature of the surface,surface material and other characteristics.The state of constant force machining of the surface is maintained by the compliant control of the robot combined with the end effector.Currently,there are two main types of robotic compliance control,namely active compliance and passive compliance.Passive compliance mainly relies on springs,damping and other mechanisms that can store a part of the external force,so as to maintain the initial state of the robot end device;active compliance is the robot through the feedback information,actively adjust some mechanisms to change the force,so that the force control tends to be stable with the target value.The process of numerical values.Active and supple control is more accurate than passive compliance,so it has continued to grow.This paper focuses on the research of robotic constant force polishing based on active compliance control.(1)According to the process requirements and technical specifications of aeroengine blade polishing,design a robot end grinding wheel polishing tool.The conventional abrasive belt wheel is modified,and the contact wheel is controlled by the guide rail sliding block module and the elastic device.The mathematical model of the whole system is established according to the structural parameter parameters of the polishing tool,the output of the guide rail sliding table and the force analysis between the tool and the workpiece.Based on this,the process of the entire control system is established,and the system with the notebook and the microcontroller as the upper and lower machine control is determined.(2)Trajectory planning for robots based on compliant polishing tools.According to the known parameters such as the axial length of the working robot and the range of the rotation angle,the tool coordinate system at the end of the working robot is established by the forward and backward kinematics of the robot,and the end effector is compensated for the pose,and the tool coordinate system is moved to the end point of the actuator..The CAD/CAM function in UG(NX)software is used to model and generate the exported tool motion track file,which is then converted into a robot-recognizable JBI format.A simplified model of six-degree-of-freedom robot is established in MATLAB,and known trajectory points are acquired and simulated to verify the feasibility of trajectory planning.(3)Decoupling the robot force/position hybrid control,and performing constant force control at the end of the robot and the normal direction of the workpiece.In order to increase the response speed and robustness of the control system,combined with the advantages of fuzzy logic control and PID control,a constant force control system is established.The proportional,integral,differential parameters used in the PID control and the parameter settings in the fuzzy logic control are obtained by simulation.According to the trajectory and fuzzy PID controller system,a robotic force/bit hybrid control system based on compliant device is built to verify the feasibility of force/bit hybrid control based on fuzzy PID algorithm.(4)Establish a polishing experiment platform according to the previously set control flow,using the robot control cabinet and STM32F103ZET6 microprocessor as the controller of the whole system,the robot control system motion track,and the single chip control the end output force.The use of the robot control platform for polishing can effectively reduce the surface roughness of the workpiece and maintain a small range of pressure between the workpiece and the tool,thereby obtaining a method based on the active compliant control of the robot polishing. |
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