Ceiling Radar Direction Detection via Time Difference of Arrival
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Solution Overview
Problem
Radar systems installed on ceilings struggle to determine the direction of movement of objects on the floor within their field of view, despite being able to detect presence and velocity through the Doppler effect.
Innovation Solution
A radar system comprising multiple receivers and a computing device that measures the time difference in receipt of reflected electromagnetic waves between receivers to determine the direction of movement of objects, with receivers arranged in a two-dimensional array to calculate motion vectors along or orthogonal to the axis between them.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a radar system is installed on a ceiling to detect objects on the floor, then the radar system can detect the presence of moving objects, but it cannot determine the direction of movement of the objects
Solution Approach 1:
The radar system divides the reception function into multiple separate receivers arranged in a two-dimensional array. Each receiver captures reflected electromagnetic waves independently, and the computing device processes the time differences between receivers to determine direction of movement. This segmentation enables directional detection capability while maintaining system simplicity.
Solution Approach 2:
The system transitions from a single-point detection approach to a two-dimensional array of receivers. By adding the spatial dimension of multiple receivers positioned at different locations, the system gains the ability to calculate time differences and determine direction of movement, transforming a one-dimensional detection problem into a two-dimensional solution.
2Measurement precision
If multiple receivers are arranged in a two-dimensional array to determine direction of movement, then the radar system can accurately calculate motion vectors, but the device complexity increases
Solution Approach 1:
The computing device performs multiple functions: it processes signals from all receivers, calculates time differences, determines direction of movement, and computes motion vectors. By making the computing device multi-functional, the system avoids adding separate dedicated hardware for each function, thereby limiting the increase in overall device complexity while maintaining high measurement precision.
Solution Approach 2:
The system uses the time differences between receivers' signals to automatically determine direction of movement and calculate motion vectors without requiring external intervention or complex additional processing hardware. The existing receiver array and computing device work together to self-determine directional information through straightforward time difference calculations.
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 accurate determination of the direction of movement of objects within the field of view, integrating seamlessly with existing radar systems without significant modifications, and is cost-effective.
Implementation Method 1
an emitted electromagnetic (EM) wave may strike an object in a field of view (FOV) of the radar system and be reflected. A receiver of the radar system may receive the reflected EM wave.
Implementation Method 2
If the object has a velocity relative to the receiver of the radar system, the reflected EM wave is shifted by the Doppler effect, relative the emitted EM wave. The Doppler effect may be used to determine the relative velocity of the object.
Implementation Method 3
determine a first time of receipt, by a first receiver, of a reflected electromagnetic wave associated with the emitted electromagnetic wave; determine a second time of receipt, by a second receiver, of the reflected electromagnetic wave associated with the emitted electromagnetic wave; and determine, based on a difference between the first and second times of receipt, a direction of movement of the object
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
A system and method for a radar system is disclosed. The method 300 includes determining 302, by a computing device, a first time of receipt, by a first receiver, of a reflected electromagnetic wave associated with the emitted electromagnetic wave. The method further includes determining 304, by the computing device, a second time of receipt, by a second receiver, of the reflected electromagnetic wave associated with the emitted electromagnetic wave. The method further includes determining 306, by the computing device, based on a difference between the first and second times of receipt, a direction of movement of the object relative to any one or a combination of the first and the second receivers.