Motorized Shade Position Tracking Through Power-Loss Sensor Drift
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Solution Overview
Problem
Motorized window treatment systems face inaccuracies in determining the position of movable components after power loss events, leading to potential misalignment and damage due to hysteresis in sensor signal generation and continued motor rotation during power loss.
Innovation Solution
A control circuit that detects power loss by monitoring supply voltage, stores accurate sensor states before power loss, and upon power-up, compares predicted and actual sensor states to calculate the correct position of the covering material, adjusting for any discrepancies to ensure accurate positioning and prevent damage.
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 inaccurate sensor state detection leading to position inaccuracies
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 action ensures that when power is restored, the system has reference data to reconstruct the position accurately without relying solely on potentially inaccurate sensor states taken during the power loss period.
Solution Approach 2:
The control circuit compares sensor states taken during normal operation with sensor states taken during power loss events. By detecting discrepancies between these sensor states and using feedback from the comparison result, the system can identify and correct position inaccuracies, ensuring reliable position determination even after power loss.
2Duration of action of moving object
If the motor continues to rotate during power loss event, then the system may complete ongoing operations, but the sensor states become inconsistent with the stored position data
Solution Approach 1:
The control circuit captures and stores the accurate sensor states and position data immediately before power loss occurs. This preliminary recording ensures that even if the motor continues to rotate during power loss, the system retains a reference point of the state before the inconsistency began, enabling later correction of position data.
Solution Approach 2:
The control circuit uses feedback comparison between the stored pre-power-loss sensor states and the actual sensor states after power restoration. This feedback mechanism detects the drift caused by continued motor rotation during power loss and enables the system to calculate corrective adjustments to restore position accuracy.
3Loss of information
If the control circuit stores sensor states during power loss, then position can be reconstructed after power-up, but hysteresis in sensor signal generation causes inaccuracies in the stored states
Solution Approach 1:
The control circuit compares sensor states taken during normal operation with sensor states taken during power loss events. By detecting discrepancies between these sensor states and using feedback from the comparison, the system can identify which sensor states are inaccurate due to hysteresis and correct the position data accordingly.
Solution Approach 2:
The control circuit replaces reliance on potentially inaccurate sensor states taken during power loss with a computational approach. By using the last known accurate position and calculating the expected sensor states based on motor rotation data, the system substitutes direct sensor measurement with a calculated value that compensates for hysteresis effects.
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
This solution ensures accurate reconstruction of the movable component's position after power loss events, preventing misalignment and damage, and maintaining aesthetic and operational integrity of the motorized window treatment system.
Implementation Method 1
A control circuit that detects power loss by monitoring supply voltage
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.