Movable Body Positioning via Load Current Retry
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Solution Overview
Problem
Existing methods for precise positioning of movable bodies relative to fixed bodies, such as in machine tools, often suffer from indexing errors due to sliding resistance and residual pressures, which require external position detecting devices that are complex, expensive, and not easily attachable, leading to operation delays.
Innovation Solution
A method that determines positioning based on load thresholds, performing retry operations from different starting positions to adjust for variations in sliding resistance, eliminating the need for external position detecting devices by using motor load current to correct positioning before clamping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a position detecting device is externally provided to detect positioning accuracy, then positioning precision is improved, but device complexity and cost increase
Solution Approach 1:
The system uses the motor's own load current as a feedback signal to detect positioning accuracy. The load current naturally varies when the movable body encounters resistance or misalignment during positioning, eliminating the need for external position detecting devices. This self-service approach allows the motor to simultaneously perform positioning and self-diagnosis functions.
Solution Approach 2:
The patent replaces mechanical position detecting devices with an electrical measurement approach by monitoring motor load current. Instead of using mechanical sensors or position detectors that add complexity, the system substitutes these with electrical current monitoring that leverages the motor's inherent electrical characteristics to infer positioning status.
2Measurement precision
If a position detecting device is externally provided, then positioning precision is improved, but loss of time increases due to operation delays
Solution Approach 1:
The system implements a feedback mechanism by continuously monitoring motor load current during positioning operations. When the load current exceeds a predetermined threshold, the system automatically determines that positioning has not been achieved and triggers a retry. This real-time feedback eliminates the need for separate position detection and reduces operation delays by enabling immediate correction of positioning failures.
Solution Approach 2:
The patent performs preliminary detection of positioning status by monitoring load current before final clamping occurs. By detecting positioning failures early through load current thresholds, the system can retry positioning before the clamping operation commits to an incorrect position, preventing the need for lengthy re-indexing operations later.
3Measurement precision
If retry operations are performed multiple times, then positioning precision is improved, but loss of time increases due to repeated operations
Solution Approach 1:
The system performs a limited number of retry operations (typically 1-3 times) rather than attempting unlimited retries. This partial action approach balances the need for positioning precision with time constraints, allowing sufficient retries to overcome transient issues like residual pressure while preventing excessive time consumption. The predetermined retry limit ensures that the system does not indefinitely postpone production.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for precise positioning without external sensors, reducing operation delays by adjusting for sliding resistance variations through retry operations, ensuring accurate engagement of gear coupling teeth and preventing index errors.
Implementation Method 1
sliding resistance between the swivel part and the fixed part
Implementation Method 2
residual pressure in the hydraulic pressure circuit which is provided to the attachment
Data Source
AI summary
In a case where the load is not smaller than the predetermined value, the positioning is not completed even when it is determined that the movable body is moved to the position supposed to be the target position, then the movable body is moved to a retry starting position different from the position supposed to be the target position, subsequently a retry operation is performed for moving the movable body from the retry starting position to the position supposed to be the target position, and consequently the positioning is completed when the load becomes smaller than the predetermined value after the retry operation is performed for a predetermined number of times.