| With the substantial increase in labor costs,a trend of"robots replacing humans"has gradually formed in China.The grain industry is no exception,and it is difficult to recruit and employ people,especially in the grain leveling operation of grain entering and leaving the warehouse.Grain leveling operations are faced with large-scale,loose and easy-to-collapse grain piles,which are difficult for manual operations and lack of automatic operation machinery.Based on the study of the screw-driven traveling mechanism and the automatic grain leveling operation control system,this paper explores the technical path to realize the automatic operation of the coarse leveling of the grain pile and the fine leveling of the grain surface.The main research contents of this paper include:（1）Dynamics and kinematics analysis of the walking mechanism of the flat-grain robot.Carry out dynamic analysis of the walking mechanism of the flat-grain robot,analyze the relationship between the propulsion force of the screw drive wheel and the driving direction,and build its dynamic model.Carry out kinematic analysis of the walking mechanism of the flat-grain robot,analyze the lateral speed and longitudinal speed of the screw drive wheel.The influence of the change of speed on the motion law of the robot,and its kinematic model is constructed.The linear relationship between the speed of the driving wheel and the speed of the body is established through experiments,the speed measurement error of the motor encoder is quantified,and the relationship between the pitch of the screw driving wheel and the helix angle is established.The motor encoder speed measurement model determines the linear relationship between the kinematic model parameterγand the angular velocity.（2）The design of the automatic grain leveling operation scheme of the grain leveling robot.It is proposed to use the manual-integrated grain pile rough leveling operation algorithm and the whole area"S"shape path planning grain surface fine leveling operation algorithm to complete the grain pile rough leveling operation and the grain surface fine leveling operation respectively;Use the speed PID algorithm,the position PID algorithm and the angle The angular velocity cascade PID algorithm precisely controls the robot’s driving speed,driving distance and steering function;The robot’s attitude angle is calculated in real time through the Mahony complementary filtering and fusion algorithm.The attitude angle fluctuates between-0.05°and 0.2°under static conditions.The attitude angle fluctuates between-4°and 4°when driving.The encoder data and IMU data are fused based on the extended Kalman filter algorithm to obtain accurate positioning output.The average relative positioning error of the robot after data fusion is about 2.7%.Complete the calibration of the ultrasonic ranging module enables the robot to maintain a safe distance of 50 cm from the granary wall when the ultrasonic interruption trigger distance is 54.43 cm.（3）The design of the control system of the flat grain robot.Based on the Free RTOS real-time operating system,the STM32 main controller chip is used to complete the hardware design and software design of the Ping Grain robot control system.The hardware design of the control system includes four unit modules:chassis motion control unit,sensor unit,action unit and communication unit.The software design of the control system is based on the Free RTOS real-time operating system.The six tasks of task,motion pose analysis task,ultrasonic obstacle avoidance task and OLED display task are coordinated and scheduled,so that the grain leveling robot can drive freely on the grain surface,and realize the rough leveling operation of the grain pile and the fine leveling of the grain level by the grain leveling robot operation.（4）Grain leveling robot test.On the basis of completing the construction of the control system,in order to test the grain leveling effect of the grain leveling robot,the grain leveling ability test,the coarse leveling operation test of the grain pile and the grain leveling operation test of the grain leveling robot were designed respectively.Through the grain leveling ability test of the grain leveling robot,it is shown that the grain leveling robot can flatten the grain pile through its own gravity and rotational motion,and the rotating leveling area of the grain leveling robot is proportional to the length of the driving wheel,and the best climbing speed is 0.274 m/s;Through the grain leveling robot rough leveling test,the feasibility of the automatic manual grain leveling operation algorithm is verified.The average rough leveling efficiency of the grain leveling robot is 0.0392 m~3/min,and the grain leveling operation The highest point of the surface is 80 mm,the lowest point is-26 mm,the data range of the grain surface height is 106 mm,the average value of the grain surface height is 14 mm,the variance of the grain surface data in the operation area is8 mm,and the flatness of the grain surface is relatively high.After the grain leveling robot precision leveling operation test,the feasibility of the"S"-shaped path planning grain surface precision leveling operation algorithm in the whole area is verified.Leveling efficiency is 4.927 m~2/min,and the height difference of the grain surface after the fine leveling operation is about 5.5 mm.Compared with the rough leveling operation of the grain pile,the flatness of the grain surface is greatly improved. |
