Ultrasonic Presence Detection Using Loudspeaker and Microphone Array
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing presence-sensing devices require specialized and resource-intensive hardware, such as dedicated ultrasonic transducers, to detect motion and provide contextual information, which is costly and power-consuming, and they often fail to offer directionality and multiple user detection effectively.
Innovation Solution
The use of on-board loudspeakers to emit ultrasonic signals and microphone arrays to analyze Doppler shifts in reflections, combined with machine-learning models, to detect presence, direction, and number of users in an environment, leveraging existing audio processing techniques to accommodate out-of-band frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If specialized ultrasonic transducers and sensors are used for presence detection, then detection precision and reliability are improved, but device cost and complexity increase
Solution Approach 1:
The patent applies universality by enabling existing audio devices (smartphones, computers, tablets) to perform presence detection functions without requiring specialized ultrasonic transducers. The device uses its existing speaker and microphone components for multiple purposes: audio output and presence detection, thereby reducing hardware complexity while maintaining detection capability
Solution Approach 2:
The invention enables the audio device to detect presence using its own built-in speaker and microphone components. The speaker emits ultrasonic signals and the microphone captures reflections, allowing the device to serve its own detection needs without external specialized sensors, thus reducing overall system complexity
2Reliability
If specialized presence-sensing hardware is deployed, then detection reliability is improved, but power consumption increases
Solution Approach 1:
The patent reuses existing audio components (speaker and microphone) for dual purposes: audio playback and presence detection. By eliminating the need for separate powered sensors and transducers, the system maintains detection reliability while significantly reducing overall power consumption of the presence detection subsystem
3Measurement precision
If dedicated sensors and processors are used for motion detection, then detection precision is improved, but device cost increases
Solution Approach 1:
The invention enables existing audio devices to perform presence and motion detection using their built-in speaker and microphone, eliminating the need to manufacture devices with specialized sensors. This approach maintains detection precision through software-based Doppler analysis while significantly reducing manufacturing costs by using components already present in consumer electronics
Solution Approach 2:
The patent uses the existing audio output capability of the device to generate ultrasonic signals, effectively copying the function of a dedicated transducer. The speaker reproduces ultrasonic frequencies that would normally require specialized hardware, allowing the device to detect presence and motion without additional manufacturing costs
4Device complexity
If traditional audio speakers are used to emit ultrasonic signals, then device complexity is reduced, but signal quality and detection precision deteriorate
Solution Approach 1:
The patent dynamically adjusts audio processing parameters to optimize ultrasonic signal generation from standard speakers. The system modifies signal characteristics based on the speaker's frequency response and operational characteristics, enabling effective ultrasonic emission and detection despite the speaker not being specifically designed for this purpose
Solution Approach 2:
The invention changes the operational parameters of existing audio components by driving the speaker at ultrasonic frequencies and adjusting signal processing parameters to compensate for the speaker's frequency response characteristics. This allows the standard speaker to effectively emit ultrasonic signals for presence detection
5Ease of operation
If existing audio processing techniques are adapted for ultrasonic frequencies, then ease of operation is improved, but detection precision deteriorates
Solution Approach 1:
The system dynamically adjusts audio processing parameters including sampling rates, filter frequencies, and signal analysis methods to optimize for ultrasonic detection. The processing adapts to the higher frequency characteristics of ultrasonic signals while maintaining the ease of operation through automated parameter adjustment
Solution Approach 2:
The patent modifies audio processing parameters such as increasing sampling rates and adjusting frequency analysis thresholds to accurately detect ultrasonic Doppler shifts. These parameter changes maintain detection precision while preserving ease of operation by automating the adjustment process within the existing audio processing framework
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 approach allows for efficient detection of user presence, direction, and multiple users without the need for specialized hardware, reducing costs and power consumption while providing contextual information, and enabling effective control of secondary devices.
Implementation Method 1
cause a loudspeaker of a computing device to emit an ultrasonic signal into an environment of the computing device
Implementation Method 2
analyzing audio data representing reflections of the ultrasonic signal off objects in the environment to detect presence or a user
Data Source
AI summary
This disclosure describes presence-detection devices that detect movement of a person in an environment by emitting ultrasonic signals into the environment, and characterizing the change in the frequency, or the Doppler shift, of the reflections of the ultrasonic signals off the person caused by the movement of the person. In addition to detecting movement, and thus presence of a person, the presence-detection devices may include a microphone array to perform techniques for identifying a direction of movement of the person, and also to perform techniques for identifying a number of people that are in the room. Additionally, the techniques described herein include processing audio signals in such a way to allow for the use of on-board loudspeakers to transmit ultrasonic signals at out-of-band frequencies.