Indoor Motion Tracking Using CW Radar Trilateration
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Solution Overview
Problem
Conventional motion tracking systems in indoor environments face challenges in achieving accurate target localization due to limitations in Doppler radar systems, which fail to estimate target range, and other systems like camera-based or Bluetooth-based systems are not suitable for privacy-sensitive scenarios or ambient lighting conditions, while FMCW radar modules are ineffective for indoor applications requiring meter-level accuracy.
Innovation Solution
A system utilizing multiple CW radar devices installed in an indoor environment, capturing Doppler data at a higher sampling rate to estimate initial target position, and employing trilateration and mesh grid representation to minimize localization errors, with a network environment processing radar data from multiple devices to compute velocity vectors and subsequent target positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If CW radar is used to detect target radial velocity, then target velocity detection is improved, but target range estimation capability deteriorates
Solution Approach 1:
The patent combines multiple CW radar devices working together to achieve both velocity detection and range estimation. Each radar provides velocity information through Doppler shift, while the spatial arrangement of multiple radars enables range determination through trilateration, merging the capabilities that single radar lacks.
Solution Approach 2:
The system transitions from single-radar measurements to multi-dimensional spatial analysis by deploying radars at different positions. This dimensional expansion allows the system to extract range information from the geometric relationships between radar positions and target positions, complementing the velocity data from Doppler measurements.
2Measurement precision
If FMCW radar modules are used for indoor localization, then both target velocity and range can be estimated, but meter-level accuracy requirement is not met
Solution Approach 1:
The patent segments the indoor environment into multiple measurement zones covered by individual CW radar devices. Each radar performs localized velocity measurement, and the segmented data from multiple zones is then integrated through trilateration to achieve precise overall positioning, overcoming the limitations of single-radar or FMCW systems.
Solution Approach 2:
The system changes the operating parameters by using multiple CW radars with higher sampling rates and implementing trilateration algorithms. This parameter transformation from single-radar FMCW mode to multi-radar CW mode enables meter-level accuracy by leveraging the spatial distribution of multiple measurement points.
3Measurement precision
If multiple CW radars are used for target tracking, then localization accuracy is improved, but computational complexity increases
Solution Approach 1:
The patent performs preliminary actions by pre-establishing the spatial coordinates of multiple CW radar devices and pre-configuring the trilateration algorithm. This preparation allows the system to efficiently process real-time measurements without complex computational overhead, as the geometric framework is already in place for rapid position calculation.
Solution Approach 2:
The system uses simplified copying of radar data processing patterns, where each CW radar follows the same data collection protocol and the trilateration algorithm applies a standardized computational template. This replication and standardization reduces computational complexity compared to handling unique, complex processing requirements for each radar individually.
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
Enables precise and accurate motion tracking in indoor environments with meter or centimeter-level accuracy, reducing computational intensity and localization errors through the use of multiple CW radar devices and trilateration-based heuristic methods.
Implementation Method 1
CW radar can be used to detect the target radial velocity. According to the Doppler principle, the frequency of a transmitted electromagnetic signal shifts because of any target movement within the transmitter vicinity.
Data Source
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Figure 4A
AI summary
This disclosure relates generally to tracking motion of target in indoor environment. The method includes estimating an initial position of the target in a mesh grid form based on radar data captured from radar devices installed in the indoor environment. For a subsequent target movement, a subsequent position of the target is estimated in the mesh grid form based on the initial position and a resultant velocity vector of the target. A number of outlier grid-points is computed with a threshold number, and based on comparison the outlier grid-points are either replaced with interpolated grid-points or the subsequent position of the target is repaired based on a probable position of the target obtained from at least one of a linear regression based analysis of prior positions of the target, prior knowledge of the target velocity and sampling interval, and a trilateration based technique.