Angle-Resolving FMCW Radar Sensor Virtual Antenna Arrays
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Solution Overview
Problem
Current radar sensors face challenges in achieving high angular resolution and measurement accuracy due to ambiguities and increased hardware costs, especially when tracking objects over time, and require more powerful processors to maintain temporal resolution in safety-relevant applications.
Innovation Solution
A MIMO radar system with a measurement cycle that switches between multiple combinations of transmitting and receiving arrays, using virtual antenna arrays and combining real and virtual antenna elements to enhance aperture and reduce ambiguities, while also utilizing previous measurement cycles' data to shorten the cycle time and improve speed data accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the distances between adjacent antenna elements are increased to reduce the number of elements and hardware costs, then the number of antenna elements and hardware costs are reduced, but ambiguities in angle measurement occur and measurement precision deteriorates
Solution Approach 1:
The patent creates virtual antenna elements by combining signals from multiple transmitting antenna elements with receiving antenna elements. These virtual elements are copies that simulate the presence of additional physical antenna elements, thereby maintaining measurement precision without increasing the actual number of hardware components. The virtual antenna array is formed through signal processing that replicates the phase and amplitude relationships of a denser physical array.
Solution Approach 2:
The patent transitions from a two-dimensional physical antenna array to a three-dimensional virtual antenna array by incorporating the time dimension through sequential transmission from multiple transmitting elements. This additional dimension allows the system to synthesize a denser effective aperture without adding physical space requirements, resolving the contradiction between element spacing and measurement precision.
2Measurement precision
If multiple frequency modulation ramps are used to improve distance and speed measurement accuracy, then measurement precision is improved, but cycle time increases and temporal resolution deteriorates
Solution Approach 1:
The patent uses data from previous measurement cycles to provide preliminary estimates of object positions and velocities. These preliminary results are then refined using current cycle data, allowing the system to achieve high measurement precision with fewer complete measurement cycles. The preliminary action from prior cycles reduces the computational burden and time required for full precision measurements in the current cycle.
Solution Approach 2:
The patent implements feedback by continuously using measurement results from previous cycles to inform and adjust the current cycle's measurements. This feedback mechanism allows the system to maintain high temporal resolution while achieving accurate distance and speed measurements, as each cycle builds upon and refines the information from prior cycles rather than requiring complete independent measurements.
3Measurement precision
If the aperture of the antenna is increased to achieve high angular resolution, then angular resolution is improved, but the number of antenna elements increases and hardware costs rise
Solution Approach 1:
The patent synthesizes a larger effective aperture by creating virtual antenna elements through signal processing combinations of transmitting and receiving elements. These virtual copies extend the effective aperture without requiring corresponding increases in physical antenna elements, thereby achieving high angular resolution while controlling hardware complexity and costs.
Solution Approach 2:
The patent extends the aperture in the virtual dimension by utilizing sequential transmission from multiple transmitting antenna elements combined with receiving elements. This creates an effective three-dimensional aperture that provides high angular resolution without requiring a proportionally large two-dimensional physical array, thus reducing hardware complexity while maintaining measurement precision.
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 improves angular resolution, reduces ambiguities, and shortens the cycle time, leading to more accurate and efficient radar measurements with reduced hardware costs and increased temporal resolution.
Implementation Method 1
Angle-resolving FMCW radar sensor
Implementation Method 2
the position of which depends on the Doppler shift and the propagation time of the radar signals
Implementation Method 3
A baseband signal is generated from a received signal by mixing it with the transmitted signal
Data Source
Figure 1
Figure 2~4
Figure 5
AI summary
Angle-resolving FMCW radar sensor having a plurality of antenna elements that are arranged in various positions in a direction in which the radar sensor is angle-resolving and form at least three transmission arrays and at least one reception array, and having a control and evaluation device that is designed for a mode of operation in which the at least three transmission arrays periodically transmit signals whose frequency is modulated in accordance with a series of modulation ramps and in which radar echoes of the transmitted signals are respectively received by a plurality of antenna elements of the at least one reception array and the angle of a located object is determined from amplitude and/or phase relationships between radar echoes that correspond to different combinations of transmission and reception arrays, wherein a measurement cycle of the radar sensor comprises at least two periods in which at least two combinations of transmission and reception arrays are respectively alternated, and the combinations of transmission and reception arrays involved are different from one another for the at least two periods.