Power Window Pinching Detection via Speed Change Analysis
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Solution Overview
Problem
Existing power window systems struggle to detect pinching of objects of intermediate hardness, leading to delayed or inaccurate detection and increased pinching load, as they are designed to differentiate between hard and soft objects using threshold values, which fails to account for objects of intermediate hardness.
Innovation Solution
An opening and closing member control system that includes a drive means, a moving speed sensing means, and a pinching sensing means. The pinching sensing means computes the change in moving speed per unit interval and total change in moving speed to detect pinching, using threshold values to confirm pinching without increasing the pinching load, and adjusts thresholds based on disturbances to prevent erroneous detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a power window system uses a single threshold value for detecting pinching, then detection of hard objects is reliable, but detection of soft objects is delayed or inaccurate
Solution Approach 1:
The patent segments the pinching detection process into two distinct phases: a first determination process using a first threshold value for initial detection, and a second determination process using a second threshold value for confirmation. This segmentation allows the system to achieve both rapid initial detection and accurate final determination, resolving the contradiction between detection speed and accuracy.
2Measurement precision
If a power window system uses a low threshold value to detect soft objects, then soft object detection is improved, but erroneous detection of hard objects increases
Solution Approach 1:
The patent divides the detection process into two stages with different threshold values. The first determination process uses a lower first threshold value to enable soft object detection, while the second determination process uses a higher second threshold value to confirm pinching and eliminate false positives. This two-stage segmentation resolves the contradiction between sensitivity and reliability.
Solution Approach 2:
The first determination process acts as a preliminary screening stage that identifies potential pinching events using a lower threshold. This preliminary action allows the system to prepare for confirmation without immediately triggering the pinching response, enabling subsequent verification with a higher threshold to prevent erroneous detections.
3Reliability
If a power window system waits for continuous threshold exceedance to detect intermediate hardness objects, then false detection is reduced, but pinching load increases and detection is delayed
Solution Approach 1:
The first determination process performs preliminary detection using the first threshold value, allowing the system to identify potential pinching events before the pinching load becomes excessive. This preliminary action enables early intervention while maintaining reliability through the subsequent second determination process.
Solution Approach 2:
The patent dynamically switches between two determination processes based on the detection state. The system transitions from the first determination process (using first threshold) to the second determination process (using second threshold) when pinching is detected, creating a dynamic detection system that adapts to different detection stages and object hardness levels.
Data Source
AI summary
A motor drives a window glass of a door of a vehicle in an opening direction and a closing direction. A rotation sensing device outputs a pulse signal in response to rotation of the motor. A controller senses pinching of an object by the window glass based on the rotational speed signal. Specifically, the controller computes a rate of change in the rotational speed, i.e., a rotational speed difference based on the rotational speed signal. The controller senses start of the pinching based on the rotational speed difference. When an amount of change in the rotational speed since the time of sensing the start of the pinching exceeds a pinching determining threshold value, the controller confirm the pinching of the object.