Motorized Window Treatment Position Recovery After Controller Reset
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Solution Overview
Problem
Motorized window treatments, such as roller shades, face disruptions due to motor overload conditions, low-line conditions, or electrostatic discharge events, which cause the microprocessor to reset, leading to inaccurate position information and potential loss of desired final positions.
Innovation Solution
A method and electronic drive unit that store the desired and present positions of the motorized window treatment in memory, allowing the controller to recall these positions after a reset and automatically drive the motor to maintain minimal interruption and achieve the desired position, using a rotational position sensor and memory to ensure accurate positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the microprocessor continuously tracks position by counting motor rotations, then position control precision is improved, but the system becomes vulnerable to reset events causing position loss
Solution Approach 1:
The system stores position information in non-volatile memory before disruptive events can occur. The microprocessor saves the current position count to EEPROM or other non-volatile storage, ensuring position data is preserved even if the microprocessor resets during motor operation.
Solution Approach 2:
The system creates a backup copy of the position information in non-volatile memory. Instead of relying solely on volatile memory or registers that would be lost on reset, the position data is copied to persistent storage that maintains data across power interruptions and microprocessor resets.
2Speed
If the system stores position data in volatile memory for fast access, then operational speed is improved, but position information is lost during microprocessor reset
Solution Approach 1:
The system performs preliminary storage of position data in non-volatile memory before potential reset events occur. The microprocessor periodically or continuously writes position information to EEPROM or other non-volatile storage, ensuring data is preserved before any disruptive event.
Solution Approach 2:
The system maintains copies of position information in both volatile memory (for fast access during operation) and non-volatile memory (for persistence across resets). This dual-storage approach allows the system to benefit from fast volatile memory access while protecting against data loss through non-volatile backup.
3Reliability
If the microprocessor resets during motor operation, then the system recovers from overload or ESD events, but position control accuracy deteriorates
Solution Approach 1:
The system saves position information to non-volatile memory before reset events occur, allowing the microprocessor to recover and resume operation with accurate position knowledge. After reset, the microprocessor reads the saved position data and continues motor control from the correct position rather than losing track.
Solution Approach 2:
The system creates a persistent copy of position data in non-volatile memory that survives microprocessor reset events. When the microprocessor resets and restarts, it retrieves the copied position information from non-volatile storage, enabling seamless resumption of position-controlled motor operation without accuracy loss.
4Reliability
If the system continuously monitors motor current for overload detection, then motor protection is improved, but the frequency of microprocessor resets increases
Solution Approach 1:
The system continuously saves position data to non-volatile memory at regular intervals or before potential disruptive events. This preliminary action ensures that even if multiple reset events occur due to overload protection, the position information is preserved and the system can quickly resume operation without significant productivity loss.
Data Source
AI summary
A method of controlling a motorized window treatment provides for continued operation of the motorized window treatment during an overload condition, a low-line condition, or an electrostatic discharge (ESD) event. The motorized window treatment is driven by an electronic drive unit having a motor, a motor drive circuit, a rotational position sensor, a controller, and a memory for storing the command. The controller stores the present position of the motorized window treatment in the memory each time the rotational position of the motor changes by a predetermined angle, such that a plurality of positions are stored in the memory. When the controller is reset due to an overload condition or ESD event, the controller recalls the desired position from the memory, determines the present position, and continues to drive the motor drive circuit in response to the command and the present position.