Back-EMF Window Position Detection for Anti-Pinch Safety
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Solution Overview
Problem
Existing power-window apparatuses for motor vehicles rely on external sensors for precise position measurement and are dependent on specific motor parameters, limiting their effectiveness and flexibility, especially in anti-pinch safety functions.
Innovation Solution
The system utilizes the back electromotive force of the d.c. electric motor to determine the window's position without external sensors, employing Pulse-Width Modulation (PWM) to isolate parasitic effects and calculate the position based on the motor's inherent physical quantities, allowing for self-calibration and independence from motor characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external sensors are used for position measurement, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The motor serves itself by using its own back electromotive force as the measurement signal. The control module measures the back EMF generated by the motor during operation to determine window position, eliminating the need for external position sensors and simplifying the system while maintaining measurement precision.
Solution Approach 2:
The back electromotive force acts as an intermediary that carries position information. By measuring this intermediate electrical signal generated by the motor's own operation, the system indirectly obtains position data without requiring direct mechanical or optical sensing components.
2Reliability
If motor parameters are specified for anti-pinch function, then reliability is improved, but adaptability decreases
Solution Approach 1:
The control module universally applies the anti-pinch detection method based on back EMF measurement that works with any d.c. motor. By using a general physical principle (back EMF) rather than motor-specific parameters, the system becomes adaptable to different motor types and specifications while maintaining reliable anti-pinch protection.
Solution Approach 2:
The system changes from relying on fixed motor parameters to dynamically measuring electrical characteristics (back EMF) during operation. This allows the anti-pinch function to adapt to varying motor parameters and conditions while maintaining reliability through real-time monitoring.
3Device complexity
If current measurement is used for obstacle detection, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The back electromotive force serves as an intermediary signal that provides more precise obstacle detection information than current alone. This electrical intermediary carries detailed information about motor load and position, enabling precise anti-pinch detection while keeping the system simple by using existing motor electrical characteristics.
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 enables precise and reliable anti-pinch functionality without external sensors, ensuring robustness and flexibility in motor replacements, simplifying the system and enhancing safety by accurately detecting pinching conditions.
Implementation Method 1
The system utilizes the back electromotive force of the d.c. electric motor to determine the window's position without external sensors
Implementation Method 2
employing Pulse-Width Modulation (PWM) to isolate parasitic effects and calculate the position based on the motor's inherent physical quantities
Data Source
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AI summary
Described herein is an apparatus for automatic movement of sliding windows in a motor vehicle, in particular a power-window apparatus, comprising a d.c. electric motor (10) that moves a window (F) so that it slides along guides, the device (20) comprising an electronic control module (21) for controlling the d.c. electric motor (10), in particular a microprocessor, the electronic control module (21) being configured for measuring a current (I) of the motor (10) and for measuring a position (X) of the window (F), the control module (21) being moreover configured for driving reversal (190) of operation of the electric motor (10) if it is verified (180) that the current (I) is higher than a threshold current (Ith) and the position (X) of the window (F) falls within a given zone (APZ) of a path (P) of movement of the window (F). According to the invention, the anti-pinch circuit device (20) is configured for measuring (130) a back electromotive force (E; Em) of the motor (10), and the electronic control module (21) is configured for calculating (180) the position of the window (F) as a function of the back electromotive force (E; Em) of the motor (10), so as to operate without the aid of external sensors. The control module (21) is configured for calculating the coefficient of proportionality (Ke) of the system via a calibration procedure.