Research On Trajectory Planning Of 7 - DOF Robot

With the rapid development of computer technology and microelectronic technology, robot technology has been developed quickly. People’s requirements in all aspects of performance of the robot are also increasing, not only to meet the requirements to complete the assigned task, but also need cost less time guaranteeing the quality of the job, so as to improve the working efficiency of the robot.In order to satisfy the requirements,seven DOF serial robot Robai Cyton Gamma 300 is taken as the object of research, the article uses five B spline curve to plan the trajectory of robot joints.In the condition of satisfying the kinematic constraints,the improved genetic algorithm is used to optimize trajectory time,and makes the joints’ motion smooth and continuous,reducing joint wear, prolonging the service life,so that the robot can move along the original path in the shortest time.Firstly, the paper introduces the present research status and future development trend of the robot technology, a comprehensive summary of the domestic and foreign scholars’ s research results on robot trajectory planning in recent years. The kinematics theory of robot is described, and the kinematics model for seven DOF serial robot Robai Cyton Gamma 300 is set up in the D-H method. The current methods for solving the inverse kinematics equation are analysed,and the genetic algorithm to optimize the BP algorithm is used for robot kinematics inverse solution to changes the end effector of a robot in Cartesian space pose into the joint variables of joint space.Then,the main methods of trajectory planning commonly used in the two aspects of the joint space and Cartesian space are introduced in detail.The process of B spline curve is constructed for each joint trajectory of the robot is studyed deeply,and the path points of the end effector in Cartesian space are collected through the robot teaching operation.The trajectory planning in cubic B spline and five degree B spline curve is conducted.In the MATLAB programming simulation, each joint trajectory planned with five degree B spline curve, the velocity,acceleration and jerk curve change smoothly,which proved the robot is steady in the process of movement.Finally, based on traditional genetic algorithm, this paper improves the coding method, crossover probability and mutation probability etc. The efficiency of the algorithm can be improved through real number coding.The ranking selection operator can be more convenient, efficient selection of individuals with high fitness.The adaptive crossover probability and mutation probability can guarantee the global optimization, at the same time can improve the local search ability.Through the comparison of the simulation results and analysis, in satisfied with the kinematics constraint condition, the improved genetic algorithm can obviously shorten the time of robot movement along the trajectory of the robot, so as to improve the work efficiency.