Ceiling Fan Speed Control with Vibration-Filtered Occupancy Detection
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Solution Overview
Problem
Existing ceiling fan control systems face challenges in accurately detecting occupancy and vacancy conditions due to interference from vibrations and wobbling, which affect the reliability of sensing signals and fan operation, and they lack effective methods to adjust fan speed for optimal thermal comfort.
Innovation Solution
A control device for ceiling fans is developed, incorporating a motor drive circuit, an occupancy sensing circuit with passive infrared, image sensing, and RADAR capabilities, along with an adaptive noise cancellation algorithm and stabilization algorithms to filter out vibrations and wobbling effects, allowing for precise occupancy detection and adaptive fan speed control to enhance thermal comfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If occupancy sensing circuits are used to detect occupancy conditions, then occupancy detection capability is improved, but the detection accuracy deteriorates due to interference from vibrations and wobbling
Solution Approach 1:
The patent extracts and removes the harmful vibration and wobble components from the sensing signals through signal processing. The control circuit identifies and eliminates the portions of the sensing signals that are caused by fan vibrations and wobbling, thereby isolating the true occupancy detection information from the noise.
Solution Approach 2:
The patent introduces an intermediary signal processing mechanism that mediates between the raw sensing signals and the occupancy detection result. The control circuit acts as an intermediary that processes the sensing signals, filtering out vibration-induced noise while preserving the genuine occupancy information before making detection decisions.
2Ease of operation
If fan speed control is implemented to improve thermal comfort, then user comfort is improved, but system complexity increases due to multiple sensing circuits and processing algorithms
Solution Approach 1:
The patent combines multiple sensing circuits (occupancy sensing, vibration sensing, wobble sensing) and their processing functions into a single integrated control circuit. This merging approach allows the system to handle multiple sensing tasks and complex signal processing within one unified component, reducing overall system complexity while maintaining advanced functionality.
Solution Approach 2:
The control circuit is designed with multi-functionality, serving as both the occupancy detection processor and the fan speed controller. It performs multiple functions including signal processing from various sensors, occupancy detection, vibration analysis, wobble analysis, and motor control, thereby reducing the need for separate dedicated circuits for each function.
3Duration of action of stationary object
If vibrations and wobbling are present during fan operation, then fan operation is maintained, but sensing signal reliability deteriorates
Solution Approach 1:
The patent converts the harmful effect of vibrations and wobbling into a beneficial signal processing opportunity. By using vibration sensors and wobble sensors to detect these phenomena, the system generates reference signals that are then used to identify and eliminate the corresponding noise components from the occupancy sensing signals, thereby transforming the harmful vibrations into useful information for noise cancellation.
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
The solution enables accurate detection of occupancy and vacancy conditions, minimizes fan wobble, and adjusts fan speed to provide optimal thermal comfort by filtering out noise and using adaptive algorithms, thereby improving the operational efficiency and user experience.
Implementation Method 1
The occupancy sensing circuit may comprise a passive infrared (PIR) sensing circuit configured to generate a sense signal that indicates the occupancy condition or a vacancy condition in the space
Implementation Method 2
the occupancy sensing circuit may comprise a RADAR circuit and one or more transmit and receive antennas for transmitting and receiving RADAR signals to detect occupancy in the space
Data Source
AI summary
A control device for a ceiling fan may have a motor drive circuit configured to control a rotational speed of a motor of the ceiling fan, an occupancy sensing circuit, and a control circuit configured to adjust the rotational speed of the motor in response to a detected occupancy or vacancy condition. The control circuit may process the signals generated by the occupancy sensing circuit to eliminate the effects of vibrations and/or wobbling of the ceiling fan. The control circuit may control the motor drive circuit to adjust the rotational speed of the motor in response to an accelerometer to minimize the magnitude of the wobble of the ceiling fan. The control circuit may be configured to learn a preferred rotational speed for the motor. The control circuit may also be configured to control the rotational speed of the motor to affect a thermal comfort level of an occupant.