Ceiling Fan Speed Control for Wobble-Aware Occupancy Sensing
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Solution Overview
Problem
Ceiling fans experience vibrations and wobbling, which interfere with occupancy sensing signals and affect the accuracy of control systems, leading to suboptimal operational conditions and thermal comfort in spaces.
Innovation Solution
A control device for ceiling fans is equipped with a motor drive circuit, an occupancy sensing circuit, and a control circuit that uses adaptive noise cancellation and image stabilization algorithms to adjust rotational speed, minimizing wobble and optimizing thermal comfort based on occupancy conditions, temperature, and humidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the ceiling fan operates at higher rotational speeds to improve cooling efficiency, then the thermal comfort in the space is enhanced, but the vibrations and wobbling increase, interfering with occupancy sensing signals and reducing measurement accuracy
Solution Approach 1:
The patent detects the fan-induced vibrations using the occupancy sensing circuit and converts this harmful interference into useful information. By analyzing the vibration patterns and frequencies detected by the PIR sensor, the system identifies when vibrations are affecting occupancy detection and automatically adjusts fan speed to eliminate the interference, thus converting the harmful vibration signal into a beneficial control feedback mechanism.
Solution Approach 2:
The system implements a feedback loop where the occupancy sensing circuit continuously monitors both the occupancy status and the fan vibrations. The control circuit processes this feedback information and dynamically adjusts the fan speed to maintain accurate occupancy detection while preserving thermal comfort. This closed-loop feedback mechanism resolves the contradiction by continuously adapting the fan operation based on real-time vibration and occupancy conditions.
2Productivity
If the fan speed is increased to improve air flow and thermal comfort, then the cooling performance is enhanced, but the wobble magnitude increases, affecting the reliability of the control system
Solution Approach 1:
The patent implements dynamic fan speed adjustment based on real-time vibration detection. Instead of operating at fixed high speeds, the control circuit continuously monitors vibration levels and dynamically modifies the fan speed to maintain optimal performance. This dynamic approach allows the system to achieve high air flow when conditions permit while automatically reducing speed when vibrations threaten control reliability, thus resolving the contradiction between productivity and reliability.
3Extent of automation
If the occupancy sensing circuit is used to detect occupancy conditions, then the automatic control function is enabled, but the vibrations from the fan create noise in the sensing signals, reducing the accuracy of occupancy detection
Solution Approach 1:
The patent converts the harmful vibration noise into a useful diagnostic tool. The occupancy sensing circuit detects both occupancy-related thermal signals and fan-induced vibration patterns. By analyzing the frequency and characteristics of the detected signals, the system distinguishes between genuine occupancy changes and vibration-induced noise, thereby converting the harmful interference into a beneficial feature that enhances automatic control reliability.
Solution Approach 2:
The control circuit acts as an intermediary that processes the raw sensing signals from the occupancy sensing circuit. It separates the occupancy-related thermal signals from the vibration-induced noise by analyzing signal characteristics and frequency patterns. This intermediary processing layer enables the automatic control function to operate reliably by filtering out vibration interference while preserving genuine occupancy detection capabilities.
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 effectively eliminates the interference from vibrations, providing accurate occupancy detection and adjusting fan speed to enhance thermal comfort and minimize wobble, 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 control device may comprise a movement sensing device (e.g., an accelerometer) configured to generate an output signal that indicates a magnitude of vibrations and/or wobbling of the ceiling fan
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.