Numerical Controller Position Error Field Collision Checking
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Solution Overview
Problem
Existing processing machines, such as machine tools, lack a method to reliably check for collisions between the tool, workpiece, and machine elements during operation, as the real kinematics of the machine are not considered in parts programming, leading to potential collisions and errors.
Innovation Solution
A method where a numerical controller determines setpoint axis values for position-regulated axes, associates virtual protection bodies with machine elements, the workpiece, and the tool, and checks for collisions by simulating the movement of these bodies, taking into account a position error field to correct for deviations from ideal positions and orientations, thereby preventing collisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the real kinematics of the processing machine are not taken into account in parts programming, then the parts program can be established without complex machine-specific data, but collisions between the tool, workpiece, and machine elements cannot be detected
Solution Approach 1:
The patent performs a preliminary collision check by virtually moving protection bodies assigned to machine elements, workpiece, and tool along the tool path defined by the parts program. This preliminary action detects potential collisions before actual machining, allowing the system to identify unsafe tool paths without requiring complex machine-specific kinematic data during programming.
Solution Approach 2:
The patent creates virtual copies (protection bodies) of the tool, workpiece, and machine elements. These protection bodies are moved virtually along the intended tool path to simulate actual machining movements. By checking for intersections between these virtual protection bodies, the system can detect collisions without requiring complex real kinematics data, thus resolving the contradiction between ease of programming and collision detection capability.
2Productivity
If position error fields are not considered in collision checking, then the collision check can be performed quickly using ideal setpoint positions, but the actual collision risk is not accurately assessed
Solution Approach 1:
The patent performs a preliminary collision check using ideal setpoint positions from the parts program to quickly identify obviously unsafe tool paths. This first pass maintains high processing speed while filtering out clearly dangerous movements before more detailed analysis.
Solution Approach 2:
The patent applies position error fields locally to specific machine elements and their protection bodies when performing the collision check. Rather than uniformly applying complex error compensation to all elements, the system selectively uses position error data for elements where it most critically affects collision risk assessment, thus balancing computational speed with prediction accuracy.
Data Source
AI summary
A numerical controller of a processing machine determines corresponding setpoint axis values based on setpoint position values for position-regulated axes operating on machine elements. Before controlling the position-regulated axes, volumes to be occupied by protection bodies associated with the machine elements, a workpiece and a tool are defined and it is checked whether the protection bodies remain disjoint while controlling the position-regulated axes. Depending on the result of the checks, the controller either controls the position-regulated axes in accordance with the setpoint position values or merely executes an error response without control. The controller contains a position error field which specifies for any given setpoint axis value an actual position the tool relative to the workpiece. The position error field is taken into consideration, at least for a subset of the protection bodies, when defining the volumes to be occupied by the protection bodies upon activation of the position-regulated axes.