Motor Restart Pinch Detection Using Pre-Braking Reference Values
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Solution Overview
Problem
Existing anti-pinch technologies for power windows and similar movable members in vehicles face challenges in reliably detecting pinches during transient motor states, particularly when the window is stopped temporarily in an intermediate position and then starts closing again, due to dynamic changes in armature current and speed influenced by factors like supply voltage, temperature, and window position.
Innovation Solution
A control apparatus that determines a reference value of the motor's physical quantity, such as current or speed, before braking, and uses this reference to detect pinches during subsequent closing movements by comparing current values to a threshold value, which is adjusted with a correction factor, allowing for efficient pinch detection even in transient states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional sensors (force or speed sensors) are used for pinch detection, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The motor controller performs pinch detection using existing motor current and speed measurements that are already available for normal motor control operations. The system serves dual purposes: controlling the motor and detecting pinches, without requiring additional dedicated sensors.
Solution Approach 2:
The existing motor control system is made multi-functional by using the same current and speed measurements for both motor control and pinch detection purposes. The controller analyzes motor parameters to detect abnormal loads indicating pinches, eliminating the need for separate detection hardware.
2Speed
If pinch detection is performed during motor start-up transient state, then detection speed is improved, but measurement precision deteriorates due to dynamic changes in current and speed
Solution Approach 1:
The system prepares by establishing baseline current and speed values before motor start-up. During the transient start-up phase, it compares real-time measurements against these pre-established baselines and expected transient profiles to detect pinches, enabling fast detection while maintaining accuracy through contextual comparison.
Solution Approach 2:
The detection algorithm adapts to the dynamic transient state by using time-varying thresholds and expectations rather than fixed values. It anticipates the natural current and speed changes during start-up and identifies pinches based on deviations from the expected dynamic profile, allowing accurate detection during rapid transitions.
3Productivity
If the anti-pinch algorithm is deactivated before the window seal is reached, then productivity is improved, but safety may be compromised
Solution Approach 1:
The system applies different detection thresholds and algorithms at different positions during window closing. Near the seal position, where normal high forces are expected, the system uses position-aware detection that distinguishes between seal contact forces and actual pinches, allowing the window to close completely while maintaining safety.
Solution Approach 2:
The detection parameters such as force thresholds and time constants are dynamically adjusted based on window position. As the window approaches the seal, the system modifies its detection criteria to account for increased normal forces, preventing false pinch detection while maintaining sensitivity to actual hazards.
Data Source
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AI summary
The pinch detector includes a first portion that, in a first situation in which the member is being closed in a first closing movement but is stopped in an intermediate position not completely closed, obtains a reference value of a measured physical quantity of the motor, when braking the motor is ordered to stop the member, said reference value representing the physical quantity of the motor just before motor braking; a second portion that, in a second situation following the first situation and in which the member is moved in a second closing movement from said intermediate position not completely closed, compares current values of the measured physical quantity of the motor to a threshold value depending on said reference value in order to detect a pinch at closing member based on a comparison result.