Rough Trajectory Planning for Redundant-Drive Machine Tools
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Solution Overview
Problem
Existing methods for determining a rough trajectory for machine tools with redundant drive devices are often computationally intensive and may not accurately reflect the physical capabilities of the machine, leading to extended machining times and potential inaccuracies in machining.
Innovation Solution
A method that iteratively constructs a rough trajectory by determining nodal points based on a specified distance condition, using a starting point from the original contour, ensuring that the high-dynamic drive's displacement limits are not exceeded, without requiring low-pass filtering or reparameterization, thus simplifying the calculation process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional methods (low-pass filtering, reparameterization) are used to determine rough trajectory, then trajectory smoothing is achieved, but computing time is excessively long
Solution Approach 1:
The contour is segmented into multiple contour sections based on distance conditions, and the rough trajectory is constructed by iteratively determining nodal points for each section. This segmentation approach avoids global filtering operations while maintaining trajectory accuracy.
Solution Approach 2:
The method performs preliminary determination of contour sections and their nodal points before constructing the final rough trajectory. By pre-processing the contour data into manageable sections with identified key points, the computation is significantly reduced while preserving accuracy.
2Ease of manufacture
If the high-dynamic drive's displacement limits are not considered in rough trajectory calculation, then calculation is simpler, but the machine tool cannot reach target points accurately
Solution Approach 1:
The method incorporates the high-dynamic drive's displacement limit as a distance condition parameter in the nodal point determination process. By adjusting the selection criteria for nodal points based on this parameter, the trajectory ensures reachability while maintaining calculation efficiency.
3Productivity
If redundant drive devices are used to increase machining speed, then productivity improves, but the complexity of trajectory control increases
Solution Approach 1:
The trajectory control is segmented into rough trajectory (for low-dynamic drive) and fine trajectory (for high-dynamic drive). This segmentation simplifies the control complexity by assigning different levels of precision to different drive devices while maintaining overall productivity.
Solution Approach 2:
The low-dynamic drive performs the partial action of covering large displacements with rough trajectory, while the high-dynamic drive handles the remaining fine adjustments. This division of labor leverages the strengths of each drive device without requiring full precision from both simultaneously.
Data Source
AI summary
The invention relates to a method for ascertaining a rough trajectory from a specified contour for controlling a machine tool which has at least two mutually redundant drive devices for carrying out superimposed movements, wherein the contour is determined by a contour function which is defined in portions at least by contour nodal points P0-Pn+1 with ascending indices and contour portion functions p0-pn assigned to the contour nodal points P0-Pn+1 and has a contour starting nodal point P0, wherein the rough trajectory is determined by a rough trajectory function which is defined in portions by rough trajectory nodal points Q0 to Qn+1 with ascending indices and has a rough trajectory starting nodal point Q0, wherein the rough trajectory starting nodal point Q0 is equated to the contour starting nodal point P0 and thenin a first iteration step, on the basis of the contour nodal points Pj to Pn+1, the index value k of which is greater than or equal to the index value j of the respective rough trajectory starting nodal point that contour nodal point Pk which has the smallest possible index value k and the distance of which from the rough trajectory starting nodal point Qj still just satisfies a specified distance condition is ascertained, andin a second iteration step, a respective following rough trajectory nodal point Qj+1 which follows the respective rough trajectory starting nodal point Qj and lies on a connecting line between Qj and Pk or between Qj and a centroid of the portion contour Pj to Pk is ascertained.