Elevator Control Device Worker Presence Detection
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Solution Overview
Problem
Maintenance workers on an elevator are at risk due to incorrect restoration of elevator operation modes, which can lead to unsafe conditions during maintenance work.
Innovation Solution
An elevator control device and method that includes a maintenance worker boarding/leaving judgment unit, platform door open/close judgment unit, switch confirmation unit, switch operation permission unit, and operation control unit, which monitor and manage the switching between normal and maintenance modes to ensure safe operations by preventing elevator travel when a maintenance worker is on board.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the elevator operation mode is switched back to normal mode after maintenance work, then the elevator can resume normal operations, but maintenance workers on the elevator car are at risk of injury
Solution Approach 1:
The system continuously monitors governor rotation data to detect whether the elevator car is occupied by maintenance workers. This feedback mechanism prevents mode switching when workers are present, resolving the contradiction by enabling safe resumption of operations only when the car is clear.
Solution Approach 2:
The system performs preliminary detection of worker presence through governor rotation analysis before allowing mode switching. By checking occupancy status in advance, the system prevents unsafe mode transitions while enabling efficient operations when safe.
2Reliability
If the governor rotation quantity detector is used to detect worker presence, then worker safety is improved, but the device complexity increases
Solution Approach 1:
The governor encoder, which already exists for speed detection, is repurposed to detect worker presence by analyzing rotation quantity differences. This self-service approach enables safety detection without adding dedicated sensors, resolving the contradiction between safety and complexity.
Solution Approach 2:
The governor encoder serves dual functions: traditional speed detection and worker presence detection. By making the existing device multi-functional, the system achieves safety monitoring without increasing hardware complexity.
3Reliability
If the system monitors governor rotation to detect worker presence, then safety is improved, but the loss of time for operation switching increases
Solution Approach 1:
The governor rotation monitoring operates continuously during maintenance mode, accumulating data without interruption. This continuous monitoring eliminates the need for time-consuming checks during mode switching, resolving the contradiction between safety and switching speed.
Data Source
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AI summary
An elevator control device having an operation control unit to control operation of an elevator in accordance with an operation mode selected by a selector switch installed at an upper part of an elevator car includes: a maintenance worker boarding/leaving judgment unit to judge whether a maintenance worker boards or leaves the elevator car on the basis of a signal from a governor encoder for detecting a travel distance of the elevator car in a hoistway; and a switch operation permission unit to permit the operation control unit to operate in an operation mode selected by the selector switch on the basis of a state where the maintenance worker boards or leaves the elevator car judged at the maintenance worker boarding/leaving judgment unit.