In order to improve the motion stability of a pointing mechanism, the trajectory planning and trajectory optimization were conducted. To obtain better motion stability, the jerk is required continuous. Therefore, high...
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In order to improve the motion stability of a pointing mechanism, the trajectory planning and trajectory optimization were conducted. To obtain better motion stability, the jerk is required continuous. Therefore, higher order polynomial or B-spline are needed and the calculation amount increases in trajectory planning. A novel hybrid interpolation algorithm "7-order polynomial + improved quartic uniform B-spline curve + 7-order polynomial" was proposed for trajectory planning, which cannot only ensure the trajectory passes through all path points but also ensure the jerk is continuous. From the first path point to the second path point and from the penultimate path point to the last path point, 7-order polynomial is chosen as the interpolationalgorithm. The intermediate path points are interpolated by improved quartic uniform B-spline curve which is newly proposed. The improved quartic uniform B-spline curve can pass through all path points and does not require complicated calculation. To carry out the trajectory planning of a X-Y pointing mechanism, the kinematic model was derived at first. Secondly, the hybrid interpolation algorithm was presented. Thirdly, the NSGA-II algorithm was applied to the multi-objective optimization which are time, acceleration and jerk. Finally, the trajectory planning experiment was conducted to prove the validity of the proposed hybrid interpolation algorithm. The experimental results show that the pointing accuracy is improved by using the hybrid interpolation algorithm and the NSGA-II algorithm. This hybrid interpolation algorithm for trajectory planning can be applied to other robots as well.
In five-axis machining, nonlinear errors arise due to deviations between the interpolated cutter contact point (CCP) and the tool cutting edge profile, which negatively impacts machining accuracy and surface quality. ...
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In five-axis machining, nonlinear errors arise due to deviations between the interpolated cutter contact point (CCP) and the tool cutting edge profile, which negatively impacts machining accuracy and surface quality. To address this challenge, a real-time optimization method for both tool position and tool axis vector is proposed, based on the interpolated CCP. First, a cutting profile surface calculation is introduced, enabling the determination of the shortest distance between the interpolated CCP and the cutting profile. This allows precise compensation of CCP errors caused by overcutting or undercutting, improving machining accuracy. Additionally, a hybridinterpolation method combining linear interpolation and quaternion spherical linear interpolation (SLERP) is employed to ensure smooth transitions in tool axis orientation. This approach maintains computational efficiency while providing stability in regions with large angular variations. Experimental results show that the proposed method significantly reduces CCP errors and surface roughness, enhancing machining precision and surface quality. The approach demonstrates high efficiency and reliability in machining complex surfaces, offering a robust solution for high-precision applications in five-axis machining.
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