Motorized Window Treatment Position Tracking Across Power Loss
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Solution Overview
Problem
Motorized window treatments experience inaccuracies in determining the position of movable components due to power loss events, leading to potential damage or aesthetic issues, exacerbated by hysteresis in sensor state generation and continued motor rotation during power loss.
Innovation Solution
A motorized window treatment system with a control circuit that detects power loss events by monitoring supply voltage, stores accurate sensor states before power loss, and calculates an accurate present position upon power restoration by comparing predicted and present sensor states, adjusting for any discrepancies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the motor drive unit uses sensor states to determine the present position of the covering material, then the position can be monitored for control purposes, but power loss events cause inaccuracies in position determination due to hysteresis and continued motor rotation
Solution Approach 1:
The control circuit stores the last known accurate position and sensor states in memory before a power loss event occurs. This preliminary recording of position data enables the system to recover and reconstruct the accurate present position after power restoration, rather than relying on potentially inaccurate sensor readings taken during the power loss period.
Solution Approach 2:
The system compares the stored sensor states from before power loss with the current sensor states after power restoration. This feedback mechanism identifies discrepancies caused by hysteresis and motor rotation during power loss, allowing the control circuit to calculate the accurate present position by accounting for these differences.
2Productivity
If the control circuit continuously monitors sensor states to track motor position, then real-time position control is achieved, but power loss during motor rotation causes sensor state inconsistencies that lead to inaccurate position data
Solution Approach 1:
The control circuit captures and stores the sensor states at the moment before power loss occurs. This preliminary action preserves the accurate position information that would otherwise be lost or corrupted during the power loss event, enabling recovery of the correct position state after power restoration.
Solution Approach 2:
The system creates a copy of the sensor states and position data from the period before power loss. This copied data serves as a reference that can be compared against current sensor readings after power restoration, allowing the system to identify and correct for any position drift that occurred during the power loss event.
3Speed
If the motor continues to rotate during power loss event, then the system maintains operational momentum, but the sensor states become inconsistent with the actual motor position, exacerbating position determination errors
Solution Approach 1:
The control circuit compares the stored sensor states from before power loss with the current sensor states after power restoration. This feedback loop identifies the discrepancy in sensor states that occurred during the power loss event, allowing the system to calculate the accurate motor position by determining how many sensor edges were missed during the rotation that continued without power.
Solution Approach 2:
Instead of relying solely on mechanical sensor feedback that may be inconsistent during power loss, the system uses computational methods to reconstruct the accurate position. By calculating the difference between stored and current sensor states and determining the number of missed sensor edges, the system substitutes computational correction for unreliable mechanical sensing during the power loss recovery period.
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
Ensures accurate determination of the movable component's position post-power loss, preventing movement beyond set limits and maintaining aesthetic alignment, thus avoiding damage and operational inefficiencies.
Implementation Method 1
detecting a power loss event based on a supply voltage falling below a predetermined low-voltage threshold
Implementation Method 2
inaccurate sensor state detection, which may in turn result in inaccurate determination of the present position. Such inaccuracies may be caused by hysteresis in the generation of the states (e.g., a high state versus a low state) of the signals produced by circuitry used to sense magnetic fields associated with rotations of the motor (e.g., a Hall-Effect sensor circuit)
Data Source
AI summary
Motorized window treatment systems are disclosed. A motorized window treatment system may include a covering material, a sensor circuit, and a control circuit. The sensor circuit may be configured to generate sensor signals indicative of a position of the covering material. The control circuit may be configured to determine a present sensor state of the sensor circuit, determine a predicted sensor state for the sensor circuit based at least in part on a power-down position recorded at a first time and a final position recorded at a second time, compare the predicted sensor state with the present sensor state, and determine a present position of the covering material based on the comparison of the predicted sensor state and the present sensor state. Methods of adjusting a position of a covering material of a motorized window treatment also are disclosed.