Research On NURBS Trajectory Planning And Control System Design Of Industrial Robot

Nowadays,with the development of industrial robot application,the more strict requirements are put forward to improve the robot work quality.In order to improve the smoothness of trajectory of the robot,faced with the robot frequently starts and stops during the operation,and meet the real-time requirements of the process,this paper,aiming at trajectory planning,velocity planning,real-time interpolation,carries out deep research on the above fields.What’s more,the trajectory quality was evaluated by contour error model,and the trajectory contour control was put forward.The main contents are as follows:(1)According to the robot configuration,the kinematics algorithm is designed to meet the fast solution and real-time performance requirements.Then based on these kinematics algorithms,the trajectory planning algorithm in joint space and cartesian space is studied to meet the real-time requirements and lay the foundation of common curve planning algorithm.(2)According to the process requirements of complex curves,a NURBS algorithm based on unified model was designed to construct the incentive trajectory and carry out trajectory planning.At the same time,a slerp posture planning algorithm based on quaternion description was designed,and S-velocity planning was used to interpolate and obtain the end-effector trajectory with well smoothness.The simulation shows that the above planning method ensures the continuous change of end-effector posture,smoothness of velocity curve and continuity of acceleration curve,reduces the impact of joint motor and improves the operation quality.(3)Based on the space curve generating from the proposed trajectory planning algorithm,the quality evaluation system of the trajectory is established by contour error model.Then based on simple curves such as lines and arcs,this paper designs contour error estimation algorithms based on tangent approximation and osculating circle approximation.Then,based on traditional cross-coupling control,the cross-coupling control in the local task coordinate frame was designed according to the robot configuration in this paper.The contour control of the planned trajectory was carried out,and the comparison experiment was designed for the 5-degree polynomials.The simulation results show that the NURBS curve based trajectory contour control performance is better than the 5-degree polynomial,which reflects the effectiveness of the proposed planning algorithm.(4)In view of the real-time requirements of robot assignment,the RTAI real-time system based on Linux framework was built,and the real-time test of the system was carried out to meet the real-time requirements of the operation.Based on the RT-system,this paper designs the trajectory planning algorithm architecture,builds the robot servo system,and develops the teaching pendant system,then the trajectory planning experiment is carried out on this platform.The simulation shows that the NURBS based industrial robot trajectory planning algorithm can improve the trajectory smoothness,avoid the problem of frequent start and stop,meet the real-time requirements,and improve the quality of robot operation.