Vehicle Closure Pinching Detection Using Motor Torque Maps
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Solution Overview
Problem
Existing closure member control devices for vehicles, which use DC motors, face challenges in accurately detecting pinching of foreign objects due to fluctuations in motor load caused by road irregularities, temporary impacts, and motor instability during start-up, leading to erroneous determinations and increased complexity.
Innovation Solution
A control device that calculates a reference torque based on stationary motor torque and adjusts it for different operational conditions, allowing for pinching determination without a mask period, using rotation speed, acceleration, and voltage detection to differentiate between pinching and disturbances, and incorporates a motor torque map to account for individual motor characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mask period is used to avoid erroneous pinching detection during motor start-up, then reliability is improved, but detection speed deteriorates because pinching cannot be detected immediately
Solution Approach 1:
The system pre-calculates and stores a torque map specific to each motor that represents normal operating torque at different rotation speeds. This preliminary preparation allows the control device to immediately compare actual torque against the pre-stored map during operation, enabling instant pinching detection without requiring a mask period during motor start-up.
Solution Approach 2:
The invention changes the detection parameter from simple load estimation to differential torque analysis by comparing actual motor torque with torque values from a pre-stored torque map. This parameter transformation allows the system to distinguish between normal start-up torque fluctuations and actual pinching conditions, enabling reliable detection from the moment the motor starts rotating.
2Productivity
If the pinching detection threshold is set low for quick detection, then detection speed is improved, but false detection increases due to motor load fluctuations from road irregularities
Solution Approach 1:
The system transforms the detection approach by changing from fixed threshold comparison to dynamic differential analysis. By calculating the difference between actual torque and torque values from the pre-stored map at corresponding rotation speeds, the system can detect pinching at any threshold level without false positives, as the differential method inherently filters out normal operational variations.
Solution Approach 2:
The control device continuously monitors motor torque and rotation speed, retrieves corresponding values from the torque map, and performs real-time differential comparison. This feedback mechanism allows the system to adaptively detect pinching conditions while automatically compensating for normal load fluctuations, maintaining both high detection speed and accuracy.
3Measurement precision
If individual motor characteristics are accounted for using a torque map, then detection accuracy is improved, but device complexity increases
Solution Approach 1:
Instead of modifying the physical motor or adding complex hardware, the invention creates a digital copy of the motor's normal torque characteristics in the form of a torque map stored in memory. This virtual model captures individual motor characteristics and allows accurate pinching detection through software-based comparison, avoiding the need for complex hardware modifications.
Solution Approach 2:
The system replaces potential mechanical solutions (such as multiple sensors or complex mechanical linkages) with an electronic/software-based torque map approach. By using computational methods to model and compare torque characteristics, the system achieves high detection accuracy while maintaining relatively simple device structure.
Data Source
AI summary
The control device for a closure member of a vehicle according to the present invention comprises: estimated load calculation means (8b) for obtaining an estimated load from a rotation speed, acceleration, and drive voltage of a DC motor (3) for driving a closure member (9); motor torque calculation means (8b) for calculating a motor torque from the rotation speed and drive voltage of the motor; reference torque calculation means (8f) for calculating a reference torque based on a stationary state of the motor torque; and pinching determination means (8c) for determining a pinching of an object based on the estimated load, motor torque and reference torque, wherein the pinching determination means determines that there is no pinching when at least one of the estimated load and the motor torque is below the reference torque even when the estimated load is greater than a prescribed threshold value.