Movable Barrier Position Sensing for Early Obstruction Detection
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Solution Overview
Problem
Existing safety devices for movable barriers, such as roller doors, often fail to detect larger obstructions like people or vehicles and are prone to environmental degradation, requiring specialist installation and being costly.
Innovation Solution
A standalone safety device that uses a position sensor and controller to monitor relative movement between a barrier and a target, sending a stop signal when abnormal movement is detected, allowing for early obstruction detection without relying on motor current or RPM, and is simpler and more cost-effective with reduced maintenance needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a safety edge system is used to detect obstructions, then the door can detect small obstructions through compression of the rubber seal, but it fails to detect larger obstructions like people or vehicles because the door weight is too light to generate sufficient compression force
Solution Approach 1:
The patent replaces the mechanical safety edge compression system with an optical detection system using light grids and photoelectric sensors. This substitution allows detection of large obstructions without relying on mechanical compression forces, as the optical beams can detect any object that blocks them regardless of the door's weight.
Solution Approach 2:
The patent introduces light grids as an intermediary detection mechanism between the door and the control system. The light grids create invisible optical barriers that detect obstructions before the door contacts them, providing early warning and allowing the door to stop or reverse without physical contact.
2Reliability
If a photoelectric cell or light grid system is used to detect obstructions, then large obstructions can be detected and collisions prevented, but the system becomes difficult to install requiring high technical competence and becomes prohibitively expensive
Solution Approach 1:
The patent divides the detection system into modular components: multiple light-emitting diodes creating individual light beams, separate photodetector elements, and distributed mounting positions. This segmentation allows flexible installation and simplifies the system into manageable units that can be installed incrementally.
Solution Approach 2:
The patent changes the operational parameters of the optical system by using low-power LEDs and simple photodetector circuits that operate at low voltages and currents. This simplification reduces the technical expertise required for installation and maintenance while maintaining effective obstruction detection capability.
3Measurement precision
If a light grid system is positioned at a single height, then it can detect obstructions at that level, but it cannot detect obstructions below the height of the optical beam
Solution Approach 1:
The patent extends the detection system from a single horizontal plane to multiple vertical levels by positioning light grids and photodetectors at different heights along the door's path. This multi-level arrangement creates vertical coverage, ensuring obstructions at any height including low-level objects are detected.
4Reliability
If motor current sensing is used to detect obstructions, then the system can identify obstructions through changes in motor current, but it cannot be used with lightweight roller doors that do not have motor load carrying bearings
Solution Approach 1:
The patent creates a universal detection system using optical sensors and light grids that can be applied to various door types including lightweight roller doors, heavy sectional doors, and garage doors. The system does not depend on door weight or motor characteristics, making it universally applicable across different door configurations and motor types.
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
The solution effectively detects obstructions early, preventing damage and ensuring user safety without the need for complex installation or high maintenance, making it suitable for various movable barrier systems including garage doors and window shutters.
Implementation Method 1
the position sensor is configured to detect movement of the target relative to the position sensor and provide an output signal to the controller
Data Source
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AI summary
A safety device (200) is provided for a movable barrier system ((100). The safety device comprises a position sensor (210) mountable, in use, to or adjacent a barrier (110). A target (220) is mountable to the other of the barrier, such that movement of the barrier causes relative movement between the position sensor and the target. A controller (240) can communicate with the position sensor. The position sensor can detect movement of the target relative to the position sensor and output a signal to the controller. The controller can receive the output signal from the position sensor, determine one or more signal characteristics from the output signal, and compare the one or more determined signal characteristics with one or more predetermined signal characteristics to determine if the relative movement between the target and the position sensor is within a predefined range. A movement detection method is also provided.