Dynamic Threshold Collision Detection in Coordinate Measuring Machines
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Solution Overview
Problem
Existing coordinate measuring machines face challenges in rapidly and accurately judging collisions between a probe or movement mechanism and an object due to the use of constant thresholds, which are inadequate for varying target speeds and accelerations, leading to potential erroneous judgments.
Innovation Solution
A coordinate measuring machine that dynamically sets thresholds based on target speed, using a load judging unit to adjust the threshold value proportionally with the target speed, and judges the load status based on the duration the current value exceeds the threshold, avoiding erroneous judgments during speed changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a constant threshold is used for judging collision, then the device complexity is reduced, but the collision judgment accuracy deteriorates at low speeds
Solution Approach 1:
The patent applies dynamics by transitioning from a static constant threshold to a dynamic threshold that varies with target speed. The load judging unit calculates the threshold based on the target speed for moving the probe, making the threshold adaptive to different operating conditions. This resolves the contradiction by improving collision judgment accuracy at low speeds without significantly increasing device complexity, as the threshold adjustment is performed through software calculation rather than hardware complexity.
Solution Approach 2:
The patent changes the threshold parameter dynamically based on the target speed parameter. The load judging unit sets the threshold in proportion to the target speed, so when target speed is high, the threshold is high, and when target speed is low, the threshold is low. This parameter change approach allows the system to maintain appropriate collision detection sensitivity across varying speeds without requiring multiple fixed thresholds or complex adjustment mechanisms.
2Ease of operation
If a constant threshold is used for collision judgment, then the ease of operation is improved, but the response time for collision detection deteriorates at low speeds
Solution Approach 1:
The system dynamically adjusts the threshold based on target speed, which improves collision detection response time at low speeds while maintaining ease of operation. The load judging unit automatically calculates the appropriate threshold based on the target speed parameter, eliminating the need for manual threshold configuration by the user. This dynamic adjustment ensures timely collision detection across different speed conditions without complicating the user interface or operation procedures.
3Speed
If a stepwise threshold is set in accordance with target speed and acceleration, then the collision judgment speed is improved, but the threshold setting complexity increases
Solution Approach 1:
The patent simplifies the threshold setting mechanism by using a direct proportional relationship between target speed and threshold, rather than requiring complex stepwise tables or multiple parameters. The load judging unit calculates the threshold as a function of the target speed parameter, which can be implemented through a simple formula or lookup table based on acceleration characteristics. This approach maintains fast collision judgment while reducing the complexity of threshold configuration and management.
Data Source
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AI summary
A coordinate measuring machine (1) includes: a probe (21) for measuring an object; a movement mechanism (22) for moving the probe; and a motion controller (3) for controlling the movement mechanism. The motion controller (3) includes: a current value detecting unit (33) that detects a current value for moving the probe (21) by the movement mechanism (22); and a load judging unit (34) that judges a status of a load applied on the movement mechanism (22) based on the current value detected by the current value detecting unit (33) and a threshold that is set in accordance with a target speed for moving the probe (21) by the movement mechanism (22). The target speed is in proportion to the threshold.