Design And Control Of Flexible Cable-driven Charging Pile Robotic System

With the rapid development of electric vehicles(EVs)and plug-in hybrid vehicles(PHEVs),the demand for charging piles has also greatly increased.Traditional charging piles need manual operation,which have very low automation.If the charging head is not unplug in time,the charging pile will be occupied all the time causing low efficiency.In addition,the popularity of intelligent park also puts forward new demand for automatic charging technology.Traditional rigid-link robots have disadvantages,such as large size and poor obstacle avoidance ability.They are not suitable for the narrow and complicated environment required by automatic charging equipment.Therefore,this paper develops a cable-driven flexible intelligent robotic system with application to automatic charging,which is delicate and dexterous.It can be used to realize the automatic charging of new energy vehicles in many occasions,such as intelligent garages and smart parking lots.Based on the analyses of the working environment and application scenarios,the function and performance index of the charging robot system is determined.Then,systematic design of the cable-driven flexible robot is proposed,which mainly includes an operating arm and a control box.The operating arm consists of three 2-DOF linkage modules and one 2-DOF cross axle module.Each module is driven by 3 steel ropes,and each rope is actuated by a motor and a guide screw mechanism,through which the rotary motion of the motor can be converted to the linear motion of the rope.During the motion of the ropes,the linkage module has constant curvature bending,thus increasing the motion precision and load capacity.All motors,transmission mechanisms,sensors and controllers are placed in a box(called the control box),which greatly reduces the mass and size of the operating arm,enabling the robot to move dexterously in a confined environment.In addition,an automatic lock-and-release mechanism is designed in the control box in order to automatically clamp and release the driving rope,and thus the operating arm and the control box can be easily separated,which is convenient for system assemblage and debug.In order to realize precise control of the trajectory,kinematic equation of the robot is derived,successfully mapping the robot pose and the motor angles,based on which pseudo inverse method is used for solving the inverse kinematics.Furthermore,the typical trajectory of the end of the robot is planned,including the trajectory of an arc,the trajectory of a straight line and the general curve trajectory.In addition,the control system is developed based on the embedded ARM processor to realize combined control of the servo motors.At the same time,trajectory planning and control algorithms are transplanted to the robot system,which are realized with Microsoft Visual C++ 6.0.In addition,the CANBUS is used to achieve the communication with the embedded control system,achieving a number of control modes including independent control and cooperative control.Thus human-computer interaction is enhanced.Based on the above work,the integration of the robot prototype is completed,and experiments are carried out,such as the straight trajectory tracking,the arc trajectory tracking and the simulated charging movement.The experiment results indicate that the robot can meet the design requirements.