Vehicle UWB Positioning With Switched Antennas Against Metal Interference
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Solution Overview
Problem
Existing Ultra Wide Band (UWB) position estimation methods face errors due to the type of vehicle and outer metal material, particularly in indoor environments with multi-path issues, leading to inaccurate distance measurements.
Innovation Solution
A UWB precision position estimation system with a UWB tag and N anchors, featuring directional or omni-directional antennas spaced at regular intervals, a switch for controlling antenna ON/OFF, and a controller for determining the position angle and distance using Two-Way Ranging and triangulation methods, minimizing interference and measurement errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional UWB position estimation methods are used, then position estimation can be performed, but measurement errors occur due to vehicle type and outer metal material
Solution Approach 1:
The system segments the position estimation process by separately determining position angle (via TWR with multiple antennas) and distance (via triangulation with multiple anchors), then combining these independent measurements to calculate final position. This segmentation allows each measurement to be optimized independently, reducing the cumulative effect of vehicle body interference on overall accuracy.
Solution Approach 2:
The system introduces an intermediary calculation step where position angle and distance are determined separately through different measurement methods (TWR and triangulation), then used as intermediate values to compute the final position. This intermediary approach allows the system to compensate for metal interference by using multiple independent measurement paths rather than relying on a single vulnerable measurement channel.
2Measurement precision
If multiple antennas are used to reduce measurement errors, then position accuracy improves, but device complexity increases
Solution Approach 1:
Multiple antennas are configured to serve dual functions: they perform both Two-Way Ranging for position angle determination and participate in triangulation for distance measurement. This multi-functionality allows the system to achieve high positioning accuracy using the same antenna array for multiple measurement purposes, reducing the need for separate dedicated components for each function.
Solution Approach 2:
The system employs periodic switching of antenna ON/OFF states at predetermined time differences to sequentially activate different antenna elements for measurement. This periodic action allows multiple antennas to be controlled through time-division multiplexing rather than requiring simultaneous operation of all antennas, reducing the real-time control complexity while maintaining measurement accuracy through sequential sampling.
3Measurement precision
If antennas are switched ON/OFF at predetermined time differences, then measurement errors are reduced, but time consumption increases
Solution Approach 1:
The system performs preliminary calibration by measuring signal delays multiple times with different antenna configurations before final position calculation. These preliminary measurements are stored and processed offline to determine optimal antenna switching patterns, allowing the actual position estimation to use pre-determined switching sequences that minimize measurement time while maintaining accuracy.
Solution Approach 2:
The system uses the measured signal delays from sequential antenna switching to automatically determine which antennas provide reliable measurements (those with delays within threshold values). This self-service mechanism allows the system to adaptively select the minimal necessary subset of antennas for accurate positioning, reducing the total measurement time by excluding antennas that would require excessive switching or provide redundant information.
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 system ensures accurate positioning between a vehicle and a smart key by reducing measurement errors caused by vehicle type and metal material, while using simpler and fewer modules, resulting in cost reduction and improved accuracy.
Implementation Method 1
measuring a delay of received signal from the UWB tag with certain number of times, determining antennas in which the measured delay of received signal with the certain number of times is less than or equal to a predetermined threshold value
Implementation Method 2
measuring the distance between UWB anchor and UWB tag measured using a triangulation method for N UWB anchors installed in the vehicle and UWB tag
Data Source
AI summary
The present invention is to perform position estimation in relation to a vehicle and a key module by using an ultra-wideband (UWB) and, specifically, relates to a method and system for precise position estimation for a vehicle, whereby position can be estimated, with effects minimized that result from the type of the vehicle and the quality of exterior metal of the vehicle. The method for precise position estimation for a vehicle over a UWB comprises the steps of: receiving, by an LIN transceiver, a position estimation-related signal delivered from an internal part of a vehicle, and transmitting the signal to a UWB transceiver to start the position estimation; the control unit measuring a predetermined number of times reception signal delays occurring in relation to a UWB tag, while turning on or off the switch of each of M antennas at predetermined time intervals; determining antennas at which the value of a corresponding reception signal delay measured the predetermined number of times is lower than a preset threshold; measuring the distances between the determined antennas and the distances between each of the antennas and the UWB tag; determining position angles with respect to the UWB tag by using a two-way ranging (TWR) positioning method on the basis of the distances between the antennas and the distances between each of the antennas and the UWB tag; measuring the distances between the UWB tag and UWB anchors measured using a triangulation method according to the M anchors and UWB tag; and estimating the position of the UWB tag on the basis of the position angles with respect to the UWB tag and the distances between the N UWB anchors and the UWB tag.