Height-Adjustable Worktop Control for Stuck Contact Sensors
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Solution Overview
Problem
In electrically height-adjustable kitchen worktops, if the contact sensor becomes jammed or bent after encountering an obstacle, the system fails to initiate an inspection run, leading to the worktop being stuck in an upper position and unable to be lowered by the operator.
Innovation Solution
A time delay mechanism in the controller that deactivates the lifting drive if the contact sensor remains actuated beyond a predefined period, ensuring the worktop remains in the upper position and preventing further operation to prevent accidental lowering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the worktop performs an inspection run after obstacle detection, then operational safety is improved, but the system becomes unresponsive if the sensor remains stuck
Solution Approach 1:
The control continuously monitors whether the contact sensor releases during the inspection run. If the sensor fails to return to the open position by the expected time, the system detects this abnormality and transitions to a fault state, preventing indefinite unresponsiveness.
Solution Approach 2:
The system dynamically transitions between operational states based on sensor behavior. When the sensor fails to release within the expected timeframe, the control automatically shifts from waiting for sensor release to activating a fault indication, making the system's response adaptive rather than static.
2Reliability
If the control waits for the contact sensor to release before allowing further operation, then safety is improved, but the system becomes unresponsive when the sensor is jammed
Solution Approach 1:
The control implements a predefined waiting period during the inspection run to allow the sensor to release naturally. If the sensor does not release within this predetermined time frame, the system proactively activates a fault state rather than waiting indefinitely, preventing excessive unresponsiveness while maintaining safety.
Solution Approach 2:
The system replaces indefinite mechanical waiting with a time-based control mechanism. Instead of passively waiting for sensor release without limit, the control uses timed thresholds to automatically transition to fault detection, substituting passive mechanical behavior with active electronic timing control.
Data Source
Figure 1
AI summary
In a piece of furniture with a height-adjustable furniture part (2), with an electric lifting drive (3) for moving the furniture part (2), with at least one contact sensor (4) arranged on the underside of the furniture part (2) and with a lifting drive (3) controlling controller (5), which stops the moving down of the furniture part (2) when the contact sensor (4) is actuated and the furniture part (2) moves up until the contact sensor (4) is released again, according to the invention the controller (5) has a time delay ( 6) which, in the event that the contact sensor (4) is not released again after a predefined period of time after its actuation, deactivates the lifting drive (3) or the controller (5), in particular disconnects it from a supply voltage (7).