Ultrasonic Ranging for Mobile Location Accuracy

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Solution Overview

Problem

Existing location-based techniques for mobile computing devices using RSSI measurements are inaccurate and inefficient due to interference and require labor-intensive mapping, which needs frequent updates with environmental changes.

Innovation Solution

A method involving a mobile computing device that outputs a radio signal requesting a ranging operation, followed by an ultrasonic pulse, and receives a response from a beacon device to determine its location based on the time difference, allowing for more accurate and efficient positioning without constant active ultrasonic transponder usage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If RSSI measurements are used for location determination, then location capability is provided, but measurement accuracy deteriorates due to interference and multi-path effects

Engineering Contradiction:

Improvelocation determination capabilityVSAvoidlocation accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent replaces the electromagnetic wave-based RSSI measurement system with an ultrasonic acoustic wave-based ranging system. The mobile device transmits ultrasonic pulses and receives echoes from walls or objects, using the time of flight of sound waves to determine location. This substitution eliminates the interference and multi-path problems that plague RF-based RSSI measurements, as ultrasonic waves have different propagation characteristics and are less susceptible to the same types of interference.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If continuous ultrasonic and radio signal processing is performed, then location tracking is maintained, but energy consumption increases

Engineering Contradiction:

Improvelocation trackingVSAvoidbattery consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent implements periodic location updates instead of continuous signal processing. The mobile device performs ultrasonic ranging operations at specific intervals or when location changes are detected, rather than continuously transmitting and processing signals. This periodic approach maintains adequate location tracking while significantly reducing the energy consumption associated with constant radio and ultrasonic signal processing.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The system utilizes the building's existing structural elements (walls, surfaces) as passive reflectors for ultrasonic waves. These structural features naturally provide the reflection needed for ranging without requiring active transponders or additional infrastructure. The mobile device itself performs both transmission and reception, eliminating the need for separate location infrastructure and reducing overall system energy requirements.

Inventive Principle:

Principle #25Self-service

3Measurement precision

If RSSI maps are created to improve location accuracy, then positioning precision improves, but system complexity and labor requirements increase

Engineering Contradiction:

Improvepositioning accuracyVSAvoidmapping system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces the complex RSSI mapping infrastructure with a direct ultrasonic time-of-flight measurement system. Instead of creating and maintaining spatial maps of signal strengths from multiple access points, the system directly measures distance by timing the flight of ultrasonic pulses. This eliminates the need for labor-intensive map creation, storage, and processing, while providing accurate location determination through straightforward physical measurement.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 enhances location accuracy and reduces battery consumption by minimizing the need for continuous ultrasonic and radio signal processing, improving precision and scalability in determining the device's location within a building.

Implementation Method 1

outputting, by the mobile computing device, an ultrasonic pulse that includes a second data packet

Methodology Applied

Scientific EffectSound wave propagation: Sound

Implementation Method 2

determining, by the mobile computing device, a time difference between outputting the ultrasonic pulse and receiving the second radio signal

Methodology Applied

Scientific EffectTime of flight: Time of Flight

Data Source

PatentEP3356841B1Cloud-coordinated location system using ultrasonic pulses and radio signals

Publication Date: 2019.10.16 GOOGLE LLC

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AI summary

In general, this disclosure describes location techniques for a mobile device. A mobile device may request permission from a server device to perform a ranging operation. Responsive to receiving an indication of allowance, the mobile device may output a first data packet via a radio signal, which is received by a beacon device that activates an ultrasonic transponder upon receipt of the first data packet. The mobile device then outputs a second data packet via an ultrasonic pulse. The beacon device receives the ultrasonic pulse and outputs a third data packet via a second radio signal that includes information identifying the beacon device. The mobile device calculates a time difference between outputting the ultrasonic pulse and receiving the second radio signal and determines its location based on the third data packet and the time difference.