Radar Ego Motion Estimation Beyond Ambiguous Velocity Limits
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Solution Overview
Problem
Conventional ego motion estimation methods for vehicles, such as those using D-GPS, wheel velocity sensors, and radar sensor systems, face accuracy limitations, especially in ambiguous velocity environments, impacting autonomous vehicle navigation.
Innovation Solution
A radar sensor system employing an algorithm that generates instantaneous three-dimensional ego motion estimates by concatenating radar frames with shifted frames to disambiguate velocity values, using linear least squares—Moore-Penrose inverse estimation to accurately estimate vehicle motion beyond the unambiguous maximum velocity of the radar system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If radar sensor systems are used for ego motion estimation, then measurement capability is provided, but the maximum detectable velocity is limited by the unambiguous maximum velocity of the radar sensor system
Solution Approach 1:
The patent transforms the velocity measurement problem from a one-dimensional limited range into a multi-dimensional solution by concatenating multiple radar frames with different velocity assumptions. By creating a concatenated radar frame that includes multiple hypotheses about vehicle velocity, the system can resolve ambiguities and detect velocities beyond the traditional unambiguous maximum velocity limit.
Solution Approach 2:
The system changes the parameter of velocity interpretation by testing multiple possible velocity values (including velocities exceeding the unambiguous maximum) against the radar data. By evaluating different velocity hypotheses and selecting the most consistent one, the system extends its measurable velocity range beyond conventional limitations.
2Measurement precision
If D-GPS is used for ego motion estimation, then position information is obtained, but accuracy is detrimentally impacted by buildings in dense urban areas
Solution Approach 1:
The patent uses static objects detected by radar (such as buildings, trees, and other environmental features) as intermediary references to estimate vehicle motion. Instead of relying on satellite signals that can be blocked, the system uses these environmental intermediaries as pseudo-static targets to calculate ego motion through velocity compensation algorithms.
Solution Approach 2:
The system replaces the GPS satellite-based electromagnetic signal system with a radar-based local environmental reference system. By substituting external satellite signals with locally detected static objects, the system achieves accurate positioning in urban canyons where GPS signals are blocked or reflected.
3Measurement precision
If wheel velocity sensors are used for ego motion estimation, then speed estimates are provided, but accuracy deteriorates in the event of slippage
Solution Approach 1:
The patent uses detected static objects in the environment as intermediary reference points to verify and correct wheel velocity sensor readings. By comparing the motion of these external references with wheel-based velocity estimates, the system can detect and compensate for slippage conditions where wheel rotation no longer correlates with actual vehicle motion.
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 high-accuracy ego motion estimation in both ambiguous and non-ambiguous velocity environments, allowing autonomous vehicles to navigate with precise sensor data without velocity limitations.
Implementation Method 1
Each of the detection points can have a radial velocity value... The shifted radar frame can include detection points of the radar frame having respective radial velocity values shifted by a multiple of an unambiguous maximum velocity value
Data Source
AI summary
Various technologies described herein pertain to a radar sensor system that performs ego motion estimation. A radar sensor system can be utilized to generate an instantaneous three-dimensional ego motion estimate of a vehicle. The radar sensor system employs an algorithm that enables generating ego motion estimates for velocities of the vehicle that can be greater than, less then, or equal to the unambiguous maximum velocity of the radar sensor system. Moreover, a single radar sensor system of a vehicle can implement the approaches set forth herein and the techniques can be applicable regardless of modulation of the radar sensor system.