Reseach On Motion Control Technology Of Rubber Tapping Robot Based On Hybrid Mechanism

As a raw material for industrial equipment and daily necessities,rubber plays an extremely important role in industrial production and daily life.Traditional rubber tapping method,which is still mainly labor-intensive production,has been far from satisfying the development of the rubber planting industry in China.The mechanization and intellectualization of rubber plantations production will be a inevitable trend in the future.In this thesis,according to the requirements of rubber tapping,a rubber tapping robot which is based on the six-degree-of-freedom hybrid mechanism is designed.The basic theory and key technologies of the robot were studied in the meantime.The main contents are as follows:A novel six-degree-of-freedom hybrid rubber tapping robot is proposed which consists of a two-degree-of-freedom(2SPU+U)parallel mechanism and a four-degree-of-freedom(RRRR)serial mechanism.The robot realizes the profiling of rubber tree secant lines through real-time feedback of two contact sensors installed in the horizontal and vertical directions at the end of the effector.The rubber tapping robot is taken as 6R serial robot through equivalent algorithmic,the forward and inverse kinematics were analysed by using the D-H method,and the velocity and acceleration formulas were drived.The forward and inverse kinematics of the two-dof parallel mechanism were analysed and the velocity and acceleration formulas were drived too.The correctness of forward and inverse kinematics of the 6R serial mechanism were validated.The theories above lay a theoretical foundation for the robot's motion control.The workspace of the(2SPU+U)parallel mechanism and the 6R series mechanism were analysed by using the limit boundary search method.The statics of the hybrid robot was analysed based on the statics equilibrium equation,the force of the end-effecter between driving force and constraint force are derived,the dual relationship of the two-dof parallel mechanism's velocity jacobin matrix and force jacobin matrix are verified.The trajectory interpolation methods of rubber tapping robot in Cartesian space and joint space were studied.A novel interpolation algorithm for arc based on equal radian data sampling is derived,the arc path is divided into the equal radians,and the dividing point always falls on the arc,eliminating the accumulated error of the traditional interpolation.The calculation of interpolation algorithm is greatly simplified.Attitude interpolation algorithm in Cartesian space was realized based on the four dimensional principle,the angular acceleration and jeak are continuous in the motion of the robot.An approximate trapezoid velocity interpolation algorithm for cycloid transition was proposed in the joint space,it is helpful to reduce the vibration and impact of the whole system and improve its life.A control algorithm which suitable for different rubber tree diameters and ensuring the robot's end effector point to the tree center in real time is proposed.The six axis motion control system based on DSP and mobile phone wireless bluetooth are designed.The closed-loop control of rubber tree in the depth of tapping was realized.