Joint Trajectory Planning For Serial Six-axis Industrial Robots

Domestic industrial robot market is huge.However,domestic industrial robot brands is weak than foreign brands in market competition.Trajectory planning technology,as one of the important technologies in industrial robot controller,not only plays an important role in improving the motion performance of the robot but also improving its market competitiveness.By comparing the trajectory planning technology in foreign industrail robot brands,domestic trajectory planning technique still needs to be improved.The purpose of this dissertation is to propose the joint trajectory planning algorithm of serial six-axis industrial robotic arm which is suitable for industrial application.In the serial manipulator,especially the six-axis manipulator,the movement speed far lower than parellel manipulator because of its mechanical structure.Therefore,the motion time is not the most important performance of the trajectory planning.But the joint motor arm joint motor power and rated current are relatively large,hence the trajectory of the smoothness of its movement is an important indicator of its performance.And the smoothness of the trajectory has great relationship with the motor torque and the motor current.With the kinematics modeled by D-H algorithm and dynamics calculated by the Newton-Euler iterative dynamic equations,the minimum energy joint trajectory planning algorithm will be applied.In minimum energy joint trajectory planning algorithm,the trajectory will be paramerized by five order B-spline curve with motion time,which is fixed,as its knot vector.The energy optimal trajectory planning is divided into three modes: the optimal joint torque,the minimun mechanical work cost and the least energy consumed by the mortoe.All three methods are studied in this paper.After that,we find that the energy optimal trajectory planning algorithm can not precisely control the shape of the motion path and needs long time to find the optimal solution,so jerk continous joint thrajectory planning algorithm will be proposed in this dissertation.Firstly,using jerk is sine curve trajectory planning algorithm to planning trajectory without blends in this algorithm.Then using the 5th and 7th polynimial to planning blends,the optimal coefficient in blends function is obtained by different methods to make its trajectory more smooth.Experiments show that when using 5th polynimial and minimum snap to abtain optimal coefficient to plan trajectory of blends has best performance.