Collision Map Planning for Real-Time Machine Tool Interference Checks
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Solution Overview
Problem
Existing interference checking techniques for multi-axis machine tools are cumbersome, computationally intensive, and often inaccurate, making real-time collision avoidance challenging due to the complexity of calculating distances and detecting interferences between CAD models of machine tools and obstacles.
Innovation Solution
The use of obstacle and tool height maps to generate a collision map, which defines a collision-free tool height above each grid cell, allowing for rapid collision checks by comparing trajectory check points to grid cells, thereby simplifying the interference checking process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If CAD models are used for interference checking, then measurement precision is improved, but device complexity and computation time increase
Solution Approach 1:
The workspace is segmented into a grid of cells, and each cell is assigned a height value representing the maximum obstacle height in that cell. This segmentation transforms the continuous CAD model into a discrete height map, reducing computational complexity while maintaining sufficient accuracy for collision detection.
Solution Approach 2:
Instead of directly using complex CAD models for real-time collision checking, the patent creates a simplified copy in the form of a height map that captures the essential geometric information (maximum heights) of obstacles. This copy can be rapidly processed without the computational burden of full CAD models.
2Productivity
If geometry primitives are used for interference checking, then computation time is reduced, but measurement precision deteriorates
Solution Approach 1:
The patent creates a height map copy of the actual obstacle geometry, preserving the true shape and height information rather than approximating with simple geometric primitives. This allows accurate collision detection while maintaining fast computation through the simplified grid-based representation.
3Measurement precision
If full CAD model analysis is performed, then measurement precision is improved, but productivity decreases
Solution Approach 1:
The continuous workspace is divided into discrete grid cells, transforming the complex problem of analyzing full CAD models into the simpler task of comparing height values at discrete locations. This segmentation enables real-time processing while maintaining accuracy by checking collision at sufficient resolution.
Solution Approach 2:
The patent changes the representation parameters from continuous CAD model coordinates to discrete grid cell heights. This parameter transformation simplifies the computational problem from solving complex geometric intersections to comparing scalar height values, enabling real-time processing.
4Ease of operation
If geometry primitives are used, then ease of operation is improved, but reliability decreases due to false positives
Solution Approach 1:
The height map creates an accurate copy of obstacle geometry from CAD models, eliminating the need for manual primitive approximation. This automated copying process preserves the true obstacle shapes while maintaining ease of operation, as the system automatically generates the height map without user intervention.
Data Source
AI summary
An object interference checking technique using collision maps. A CAD model of a workpiece is converted to an obstacle height map defining obstacle height above a reference plane for each cell of a grid. A CAD model of a tool is used to construct a tool height map. The obstacle height map and the tool height map are used to generate a collision map defining a collision-free tool height above each grid cell of the collision map. The collision map is generated by scanning the tool height map over the obstacle height map and, for each scan point, determining a height of the tool height map which results in no interferences between any pixel of the tool height map and a corresponding pixel of the obstacle height map. A collision check of a tool trajectory is then performed by comparing trajectory check points to grid cells of the collision map.