Mobile Robot Radar Obstacle Detection Using Synthetic Aperture
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Solution Overview
Problem
Autonomous moving objects, such as mobile cleaning robots and robotic lawn mowers, face challenges in reliably detecting obstacles using single radar sensors due to ambiguity in object localization and complexity associated with multi-antenna arrays and beamforming techniques, especially in real-world environments with multi-path fading.
Innovation Solution
The implementation of synthetic aperture radar (SAR) technology using a single radar sensor, which creates a virtual array of antennas by moving the robot and taking repeated measurements, allowing for spatially resolved obstacle detection without the need for trilateration or multi-antenna arrays, and enabling detection of obstacles in various spatial angles, including those above the movement path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple distance sensors are used with trilateration or beamforming, then object localization precision is improved, but device complexity increases
Solution Approach 1:
The patent applies synthetic aperture radar processing to transform temporal signal variations (as the robot moves along its trajectory) into spatial resolution. By moving the single antenna through different positions and processing the phase-coherent signals accordingly, the system creates a virtual array that resolves objects in angular space, effectively adding a spatial dimension through temporal motion.
Solution Approach 2:
The patent creates a virtual copy of a multi-antenna array system using a single physical antenna that moves through space. The synthetic aperture radar processing generates signals that are equivalent to what would be obtained from multiple stationary antennas, allowing the robot to achieve multi-antenna performance without the physical complexity of multiple antennas.
2Measurement precision
If beamforming techniques are used with multiple receiver antennas, then spatial resolution is improved, but device complexity and cost increase
Solution Approach 1:
The patent transforms the spatial arrangement problem into a temporal processing problem. Instead of requiring multiple antennas positioned in space simultaneously, the system uses a single antenna moving through space over time, with synthetic aperture radar processing converting the temporal sequence of measurements into spatial resolution equivalent to a multi-antenna beamforming system.
Solution Approach 2:
The patent creates a virtual multi-antenna receiver system using signal processing. The synthetic aperture radar algorithm generates complex signals that replicate the output of multiple receiver antennas performing beamforming, allowing the system to achieve high spatial resolution without physically implementing multiple antennas and their associated phase-coherent receiver chains.
3Device complexity
If a single radar sensor is used, then device complexity is reduced, but object localization precision deteriorates due to ambiguity
Solution Approach 1:
The patent resolves the localization ambiguity of a single antenna by introducing the temporal dimension of motion. As the robot moves, the single antenna samples the electromagnetic field at different positions. The synthetic aperture radar processing uses these temporal variations to reconstruct the spatial distribution of objects, converting the single-point measurement limitation into a distributed spatial measurement capability.
Solution Approach 2:
The patent creates virtual signals from multiple antenna positions using a single physical antenna. The synthetic aperture radar processing generates complex signals that are equivalent to what would be measured by multiple antennas at different locations, allowing the system to achieve multi-antenna localization precision without the physical complexity of multiple antennas.
4Measurement precision
If phase coherent signals are required for beamforming, then measurement precision is improved, but device complexity increases due to receiver chain requirements
Solution Approach 1:
The patent creates a virtual phase-coherent multi-antenna receiver system using signal processing. The synthetic aperture radar algorithm processes the signals from a single antenna to generate complex signals that replicate the phase-coherent output of multiple receiver antennas, achieving high-precision angular reconstruction without the hardware complexity of multiple phase-coherent receiver chains.
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 provides a robust and accurate obstacle detection system that is simpler, more cost-effective, and capable of detecting obstacles likely to collide or not, with improved signal-to-noise ratio and decision-making accuracy for control commands, while not being limited to horizontal plane detection.
Implementation Method 1
a radar sensor (110) mounted on the autonomous moving object and configured to scan a volume (150) in front of the object during a movement of the object (100) along a movement path (L)
Data Source
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Figure 3~4
Figure 5A~5C
AI summary
The disclosure relates to an autonomous moving object (100) comprising: a radar sensor (110) configured to scan a volume (150) in front of the object, and a radar signal processor (120) configured to: acquire a sequence (170) of radar responses, each radar response of the sequence (170) being acquired at a different position (P) of the autonomous moving object (100), and perform synthetic aperture radar processing of at least parts of the acquired sequence (170) of radar responses to obtain a synthetic aperture radar image (180a) representing response amplitude as a function of at least distance and angle with respect to the radar sensor (110), the autonomous moving object (100) further comprising: a controller (130) configured to detect presence of a potential obstacle (160) within a pre¬ defined sub-volume (155) in front of the autonomous moving object (100) by analyzing the synthetic aperture radar image (180a) and, in response to detecting presence of a potential obstacle (160), output a control command configured to cause a changed movement of the autonomous moving object (100).