Design Of Parallel Picking Mechanism For Agricultural Robot Based On Visual Servo

Since the twenty-first century,the automation technology has been developing rapidly,and which had penetrated into the production of agriculture,and more and more attention to agricultural automation and intelligent by people.The agricultural harvesting robot is a typical automation and intelligent products,and it had become one of the hot research topics around all over the world.The agricultural harvesting robot is a complex and comprehensive system,and the picking mechanism is an important basis part of the agricultural harvesting robot which has picking function.Therefore,this paper designed the parallel picking mechanism for agricultural robot on visual servo,and it has used digital image processing technology to identify and locate the target.We establish the relationship between the target position in the image and the motion control volume of parallel picking through calibration experiments.MCU receives the motion control volume and drives linear actuator through the relay module.The main researches were as follows:(1)We had designed the mechanical body of-the parallel picking mechanism,and explained the structure of it.We had analyzed the degrees of freedom and its position inverse solution,and the kinematics simulation is carried out by using Adams software.(2)Designing the vision system and control system of the parallel picking mechanism,collecting the image information,and using OpenCV for image to image processing,such as gray-scale processing,threshold processing,opening and closing operation treatment,eliminated background information.We identified multiple targets and selected the largest area one to be the target for first picking.The four vertex coordinates of the object with the minimum circumscribed rectangle are solved on the image,and the position of the target can be calculated.(3)According the coordinate of the goal and picking in the image,We can calculate the distance between the two values,and the angle which connected with X axis.We calibrate the corresponding relation between the distance values and the picking mechanism bending degrees through the experimental method.We calibrate the corresponding relation between the angle values and bending directions through the experimental method.We set up six kinds of direction angles and four bending angles,respectively with the characters’ a’to’ f ’on behalf of the bending direction,with the characters’ g ’ to ’ J ’ represents the bending degree.(4)Computer as the upper computer,microcontroller as the lower computer.The upper computer calculated the motion control volumes which were represented by two characters,then send to the lower computer through the serial communication.MCU matched the character and calculated steering angle and bending angle in the program.According to the direction angle value of the picking,MCU gives the appropriate value to PI pin.According to the value of bending angle,MCU calculated the keeping time of the PI in the direction angle.The parallel picking mechanism could be driven by the relay module to complete the appropriate action.(5)Taking the cotton as a specific picking object.The experiment carried out by the parallel picking mechanism based on visual servo,which proved the feasibility of picking.