6-DOF Manipulator Motion Trajectory and Attitude Planning Based on NURBS Curves and Surfaces

• Main Authors: Tsung-Chi Yeh, 葉宗祺
• Other Authors: Chin-Sheng Chen
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/46xnyy

碩士 === 國立臺北科技大學 === 自動化科技研究所 === 104 === Traditionally, 6-DOF manipulator trajectory planning is only based on the trajectory of tool contact locations and takes the inverse kinematics transformation to get the angular position of each axis. However, the motion states for each axis will beyond the mechanical specification (velocity, acceleration or jerk) when we consider the tool pose in the high curvature motion trajectory. That will affect the machining performance and even destroy the manipulator. This thesis proposes the 6-DOF manipulator motion trajectory and attitude planning based on NURBS curves and surfaces. The key techniques include: (1) NURBS curve pre-processing, (2) NURBS curve planning, (3) NURBS curve and surface interpolation, and (4) planning of motion trajectory attitude. Firstly, the curve segmentation is applied to filter the line segments and separate the different NURBS curve segments. Then, the estimated feedrate, which satisfies the chord accuracy and maximum feedrate limitation, can be evaluated by adaptive feedrate. Furthermore, the above estimated feedrate will be fed into two kinds of S-Curve and S-L-Curve ACC/DEC profiles based on mechanical specification, to generate accurate servo command by compensated NURBS curve and surface interpolator. The tool pose is designed according to user’s requirements in the final step. The proposed method simultaneously satisfies the specifications of chord accuracy, the limitation of maximum velocity, acceleration, jerk and feedrate error in each segment. Finally, the proposed methods are implemented to control the 6-DOF manipulator to verify the motion performance.