Aperture Closure Control Using Discriminated Pulse Counting
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Solution Overview
Problem
Existing motorized aperture closure systems, such as garage doors, lack effective monitoring mechanisms to slow down movement near extremes and detect resistance or foreign bodies, which can lead to inaccurate positioning and potential damage.
Innovation Solution
A control arrangement that includes a pulse generator, counter, and discriminator to create and differentiate between first and second type pulses based on the position of a rotatable member with irregular features, allowing for precise monitoring of aperture closure member movement using a sensor and Hall effect sensor, and a control circuit to modulate signal current for motor control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a simple pulse counting system is used to monitor aperture closure member movement, then the device complexity is reduced, but the positioning precision and ability to detect extreme positions are insufficient
Solution Approach 1:
The pulse train is segmented into two types: first type pulses generated at regular intervals by evenly spaced teeth, and second type pulses generated at irregular intervals by the irregularity in the tooth pattern. The discriminator segments the pulse processing by identifying and differentiating between these two pulse types, enabling precise position detection through selective counting of appropriate pulses based on current position state.
Solution Approach 2:
The discriminator acts as an intermediary component between the pulse generator and the counter. It receives the mixed pulse train, discriminates between first and second type pulses based on their temporal patterns, and selectively passes appropriate pulses to the counter. This intermediary function enables precise positioning without requiring complex direct sensing mechanisms.
2Productivity
If the closure member moves at high speed throughout its range, then the productivity is improved, but the safety and damage risk increase when approaching extreme positions
Solution Approach 1:
The irregularity in the tooth pattern is positioned to generate a second type pulse before the closure member reaches its extreme position. This preliminary pulse serves as an advance warning signal, allowing the control system to prepare for and execute speed reduction before the member actually reaches the extreme, thereby maintaining both productivity and safety.
Solution Approach 2:
The system uses feedback from the discriminator's identification of second type pulses to control the motor speed. When a second type pulse is detected indicating approach to extreme position, the control circuit reduces motor speed. This closed-loop feedback mechanism ensures safety at extremes while allowing high-speed operation during normal travel.
3Measurement precision
If no discrimination between pulse types is implemented, then the device complexity is reduced, but the ability to provide accurate positioning indication and detect foreign bodies is lost
Solution Approach 1:
The tooth pattern includes regularly spaced teeth that generate periodic first type pulses during normal operation, providing continuous position feedback. The irregularity creates a distinctive non-periodic second type pulse pattern at specific positions. The discriminator exploits these periodic and non-periodic patterns to provide accurate position indication and detect anomalies such as foreign bodies.
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
Enables accurate positioning and safe operation of aperture closure members by distinguishing between regular and irregular features to adjust counting resolution, ensuring precise control and reducing the risk of damage from foreign bodies or resistance.
Implementation Method 1
The sensor may include a magnet and a Hall effect sensor, both in proximity with the rotatable member to sense changes in magnetic field as the features pass the sensor.
Data Source
AI summary
An aperture closure member control arrangement includes a disc which rotates as the aperture closure member moves. The disc has a ring of teeth. A sensor, such as a Hall effect sensor and permanent magnet, detect the passage of teeth as a cyclic waveform of amplitude and frequency determined by the spacing of the teeth, and the speed of rotation of the disc. An irregularity in the form of a missing tooth creates an irregularity in the output of the sensor, in the form of a pulse of greater amplitude and lower frequency. Accordingly, pulses from the irregularity can be discriminated and counted to provide a coarse indication of position, or pulses from the teeth can be counted, to provide a fine indication.