Research On Attitude Adjustment System Of Electric Vehicle Automatic Charging Robot

At present,the development of new energy trams is changing with each passing day.And the automatic driving technology has been demonstrated and operated successively,which drives the emergence of automatic charging technology.But compared with the man-made charging,the manipulator used to realize the automatic plug-in of the charging gun is rigid.Once the vehicle position and posture change,it may cause damage to the charging arm,especially in the case of moving of vehicles such as unmanned threedimensional garage.In order to solve the above problems,two kinds of snake arm pose adjustment technologies are proposed for different charging stages,which can make the snake arm adapt to the vehicle posture change and protect the snake arm from damage.In order to realize the attitude adjustment strategy based on the feedback of inertia measurement unit(IMU),a forward kinematics model of snake arm based on matrix transformation and Denavit-Hartenberg method(D-H method)is established.Then,the special solution method of inverse kinematics of snake arm is proposed.Then,the kinematics is verified in the modeling software.The attitude solution of snake arm based on Mahony complementary filter algorithm is completed.The gyroscope is compensated by accelerometer,and the precise end angle value is obtained;Finally,the bending model of cantilever beam is used to simulate the bending of the flexible gun head.The distance of the vertical direction of the snake arm should be adjusted at different bending angles is obtained.The rope length model and rope force model of snake arm are analyzed in the strategy of posture adjustment based on the relaxed rope.The model of rope length of snake arm is established by using vector method.The rope is divided into several segments and expressed in corresponding coordinate system.The sum of the modulus length of the rope segment vector is the length of the rope.Then,based on the simplified model of snake arm,the dynamic equation of snake arm is established by Lagrange method.The joint torque of snake arm in different states can be calculated according to the equation.After that,the analysis of the rope force of snake arm is completed,and the force of rope to the snake arm at different contact points is analyzed.The tension of the rope should be calculated to keep the snake arm static under gravity.Finally,the design of the software and hardware parts of the two control systems is completed,including the selection of chip and the choice of communication protocol.Then the software flow of the two control systems is designed.After that,the experimental platform of snake arm is built,and the effect of the two control systems is verified.When the trajectory of the position and attitude adjustment system based on IMU feedback is not in line with the expectation,the reason for the error is found out and the modified control system realizes the purpose of adjusting the flexible gun head to the level,Then,the actual effect of the posture adjustment system based on the relaxed rope is verified.The results show that the snake arm can change with the change of vehicle position and posture in real time after the rope is loosened,and the snake arm can return to normal state after tightening the rope,and achieve the expected effect.