Abstract: To solve the problem of sorting coal gangue in coal mine production,a robot sorting scheme was proposed in this paper,and the phenomena of time delay,jitter,shock and low sorting speed when the robot is tracking and sorting coal gangue were analyzed and discussed.It was found through analysis that the main reason for these phenomena is because coal gangue is a large-scale,fast-moving sorting object,and it determines that the mechanical body of the robot has a large inertia load.The traditional tracking algorithm is not suitable for fast tracking and stable grabbing of large-mass and dynamic target because of the large amount of data.Specific to this problem,a dynamic target grabbing algorithm based on cosine law-PID was proposed in combination of actual working conditions and the advantages of different tracking methods.First of all,the trajectory planning was carried out by using the law of trapezoidal velocity motion,and the gate-shaped trajectory with arc transition was established.Then a mathematical model was established for the grabbing of large-mass,dynamic targets in a dynamic environment,specific to which,a dynamic target grabbing algorithm based on cosine law-PID was put forward.This algorithm first calculates the theoretical grabbing point of the robot through the law of cosine,and after controlling the robot to reach the theoretical grabbing point rapidly,it controls the end of the robot arm to synchronize with the coal gangue through the position-speed dual-loop PID algorithm.The test results of the algorithm show that the calculation of the theoretical grabbing point through the law of cosine can reduce the time that the robot arm tracks the coal gangue to a great extent,and make the robot end quickly approach the target,improving the tracking efficiency.The algorithm controls the robot arm to synchronize with the coal gangue through the position-speed dual-loop PID algorithm in order to ensure that the manipulator grabs the coal gangue stably and accurately,which effectively solves the problem of time delay,jitter and shock during the grabbing.The experimental results of the prototype show that the algorithm can enable the coal gangue sorting robot to grab the large-mass dynamic targets stably and accurately at the optimal time,and the grabbing speed of a single robot can reach 25 times/min,which verifies the accuracy,efficiency and stability of the algorithm.