Hybrid Acoustic RF Indoor Positioning System
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Solution Overview
Problem
Current indoor positioning systems face challenges with multipath reflections and calibration difficulties due to the use of radio frequency signals, and acoustic-based systems require numerous emitters and struggle with penetration through obstructions.
Innovation Solution
A hybrid acoustic/RF positioning system that uses modulated acoustic ranging signals and a signal processor to calculate phase differences and time of arrival, allowing for self-calibration and accurate positioning with reduced infrastructure calibration needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If radio frequency signals are used for indoor positioning, then positioning coverage is achieved, but positioning accuracy deteriorates due to multipath reflections
Solution Approach 1:
The patent combines acoustic signals and radio frequency signals into a hybrid positioning system. Acoustic signals are used for accurate distance measurement through time-of-flight calculations, while RF signals provide positioning coverage and device communication. This merging resolves the contradiction by using each signal type's strengths to compensate for the other's weaknesses.
Solution Approach 2:
Acoustic signals serve as an intermediary for precise distance measurement between devices and access points. The system uses acoustic time-of-flight as a mediator to establish accurate range measurements that are then combined with RF signal data, allowing the system to achieve both coverage and accuracy that neither signal type could provide alone.
2Measurement precision
If more radio beacons are placed in the environment to improve positioning accuracy, then positioning precision improves, but system cost and calibration complexity increase
Solution Approach 1:
The system performs self-calibration using acoustic signals. Devices measure acoustic time-of-flight to automatically determine their positions and use these measurements to calibrate the RF positioning network. This eliminates the need for manual calibration of each beacon, allowing the system to improve accuracy by adding beacons without proportionally increasing calibration complexity.
Solution Approach 2:
The system changes the calibration approach from manual coordinate input to automatic acoustic measurement-based calibration. By using acoustic time-of-flight parameters to automatically determine device positions and calibrate the network, the system can scale beacon density without linearly increasing calibration effort.
3Measurement precision
If acoustic signals are used for positioning, then positioning accuracy improves, but signal penetration through obstructions deteriorates
Solution Approach 1:
The hybrid system merges acoustic and RF signal paths. Acoustic signals provide accurate positioning measurements in line-of-sight conditions, while RF signals provide positioning capability when acoustic signals are blocked by walls or obstructions. The system fuses these complementary signal paths to maintain both accuracy and penetration capability.
Solution Approach 2:
The system dynamically changes which signal type is used for positioning based on environmental conditions. When acoustic signals are available and provide good measurements, the system uses them for high-accuracy positioning. When obstructions block acoustic paths, the system switches to or supplements with RF-based positioning, changing the operational parameters to match the physical environment.
4Reliability
If a significant number of acoustic speakers are distributed to cover an area, then positioning coverage improves, but system cost and complexity increase
Solution Approach 1:
The system makes existing devices (smartphones, tablets, laptops) serve multiple functions: they act as both RF receivers for communication and acoustic receivers for positioning. This universality eliminates the need for dedicated acoustic speaker infrastructure, as any device with a speaker can emit acoustic ranging signals and any device with a microphone can receive them, providing coverage without adding specialized infrastructure.
Solution Approach 2:
Existing devices in the environment self-serve as acoustic transmitters and receivers. Rather than requiring a centralized acoustic infrastructure, the system uses the devices themselves to emit and detect acoustic signals, turning the devices into their own positioning infrastructure and eliminating the need for separately deployed acoustic speaker systems.
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 system provides accurate, reliable, and cost-effective indoor positioning with reduced calibration requirements and improved penetration through obstacles, enabling precise location determination and automatic mapping of environments.
Implementation Method 1
a first acoustic transducer disposed along a first axis of the positioning node and coupled to a first acoustic ranging signal that is modulated using a first ranging sequence, the first acoustic transducer configured to transmit the first acoustic ranging signal to the secondary device
Implementation Method 2
an acoustic receiver disposed on the secondary device and configured to detect the first and second acoustic ranging signals
Implementation Method 3
to calculate a time of arrival of the first and second acoustic ranging signals
Implementation Method 4
to calculate a phase difference between the first and second acoustic ranging signals using the first and second acoustic ranging sequences
Implementation Method 5
to determine the angle between the positioning node and the secondary device from the plurality of angles of arrival using a difference between the time of arrival of the first and second acoustic ranging signals
Data Source
AI summary
The present technology may be directed a system for determining an angle and distance between a positioning node and secondary device using a plurality of acoustic transmitters to transmit acoustic ranging signals that are modulated using ranging sequences, respectively. The system includes an acoustic receiver to detect the acoustic ranging signals, and a signal processor to calculate times of arrival and a plurality of aliased angles of arrival of the acoustic ranging signals. An anti-aliasing module may select an angle of arrival from the calculated plurality of aliased angles using the times of arrival of the acoustic ranging signals. A time of flight may be calculated from a comparison of times of arrival for radio signals and the acoustic signals. The time of flight may be used to calculate the distance between the positioning node and secondary device.