Position-Dependent Force Limiting for Automatic Doors
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Solution Overview
Problem
CNC machines pose safety hazards due to their automatic operation and powerful tools, particularly with the moving door mechanism that can pose risks to operators and bystanders during opening and closing.
Innovation Solution
A control system for a moveable door that includes a direction detector, position detector, and control unit to regulate the force and acceleration based on the door's position and direction, implementing position-dependent torque limiting to ensure safe operation by reducing force when the door is closing and entering a 'danger zone'.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the door uses a powerful force generating element to ensure rapid opening and closing, then the door operation speed and productivity are improved, but the safety risk increases due to potential crushing or trapping hazards
Solution Approach 1:
The system dynamically adjusts the force generating element's output based on real-time door position feedback. The control system modifies acceleration and force parameters according to the door's location in its travel path, allowing high speed during safe zones while reducing force in danger zones to prevent crushing hazards
Solution Approach 2:
The patent changes the operational parameters (acceleration, force, speed) of the force generating element based on door position. By monitoring position and adjusting parameters dynamically, the system achieves both high productivity when safe and safety when approaching closed or open positions where trapping could occur
2Ease of operation
If the door applies high force to overcome friction and inertia during motion, then the door can move smoothly and quickly, but the risk of injury to operators increases
Solution Approach 1:
The system continuously monitors door position and feeds this information back to the control system, which adjusts the force generating element's output accordingly. This closed-loop control ensures smooth operation while preventing excessive force that could injure operators near the door
Solution Approach 2:
The control system proactively reduces force before the door reaches positions where operators might be present. By anticipating potential hazard zones and pre-reducing force in advance, the system prevents injury while maintaining smooth motion during safe operation phases
3Device complexity
If the door mechanism is designed with simple force control, then the device complexity is reduced, but the ability to prevent crushing hazards in specific positions is compromised
Solution Approach 1:
The door system monitors its own position and automatically adjusts its force application without external intervention. The integrated position sensing and control system enables the door to self-regulate force in danger zones, preventing crushing hazards while maintaining relatively simple overall system architecture
Data Source
AI summary
A method of controlling the motion of a moveable door includes determining the direction that the door is moving with respect to its anticipated closed position, and based on the direction, regulating an amount of force that is available to the door for its motion. The method may further include monitoring the position of the door as it is moving, and adjusting the motion of the door and regulating the amount of force available to the door for its motion, based on the calculated difference between the door's position as detected during monitoring and its expected position.