Rear Axle Center Positioning Using IMU Roll Pitch Compensation
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Solution Overview
Problem
Tractors face challenges in accurately determining their position due to the offset of GPS antennas from the rear axle center, exacerbated by vibrations and roll/pitch movements, which existing technologies struggle to compensate for effectively, leading to inaccurate positioning estimates.
Innovation Solution
The use of multiple inertial measurement units to determine and combine roll and pitch data, potentially with existing camera and GPS unit IMUs, and applying these measurements through a Kalman filter to accurately translate GPS antenna positions to the rear axle center, while also considering vibration levels to adjust trust in sensor readings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If GPS antenna is located on the roof of the tractor to enhance signal reception, then signal reception is improved, but positioning accuracy deteriorates due to offset from rear axle center and exacerbation of vibration and roll/pitch
Solution Approach 1:
The patent introduces an intermediary transformation model that mediates between the GPS antenna position and the rear axle center position. This model uses roll and pitch angle measurements to calculate the precise offset transformation, thereby resolving the positioning inaccuracy caused by the GPS antenna's displaced location on the roof.
Solution Approach 2:
The patent changes the parameter approach by incorporating roll and pitch angle measurements into the positioning calculation. Instead of directly measuring position at the rear axle center, the system measures angles at the GPS antenna location and transforms these parameters to obtain accurate rear axle center positioning, thereby compensating for the offset.
2Measurement precision
If multiple inertial measurement units are used to determine roll and pitch, then positioning accuracy is improved, but device complexity increases
Solution Approach 1:
The patent merges multiple inertial measurement units into a unified positioning system. By combining data from multiple IMUs, the system achieves more accurate roll and pitch measurements while managing complexity through integrated processing. The merged IMU data provides redundant measurements that improve accuracy through averaging and cross-validation.
Solution Approach 2:
The patent makes the inertial measurement units multi-functional by using them not only for roll and pitch measurement but also for vibration level detection and trust assessment. This multi-functionality reduces the need for separate dedicated sensors, thereby managing system complexity while maintaining high measurement precision.
3Ease of manufacture
If existing camera and GPS unit IMUs are utilized, then cost is reduced, but measurement accuracy deteriorates due to lower fidelity sensors
Solution Approach 1:
The patent merges data from multiple lower-fidelity IMUs (including camera and GPS unit IMUs) to achieve accuracy comparable to higher-cost sensors. By combining the measurements and applying data fusion techniques, the system compensates for the individual limitations of each low-cost sensor while maintaining overall measurement precision.
Solution Approach 2:
The patent implements feedback mechanisms where the system continuously monitors the quality and trust level of IMU measurements. Based on this feedback, the system dynamically adjusts the weighting and processing of measurements from different IMUs, allowing it to maintain high accuracy even when using lower-fidelity sensors by compensating for their limitations through adaptive processing.
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 more accurate and cost-effective tractor positioning estimates by compensating for roll and pitch, allowing for precise control of steering and operation even without continuous GPS signals, using existing hardware to enhance accuracy and reduce costs.
Implementation Method 1
The example tractors, computer-readable mediums and methods determine the roll and pitch of the tractor by utilizing multiple inertial measurement units and combining the data from the multiple inertial measurement units
Implementation Method 2
the data is combined using a Kalman type filter, such as an extended Kalman filter
Implementation Method 3
Global positioning systems, also known as global navigation satellite systems, are sometimes used to determine a geo-referenced location of the tractor
Data Source
AI summary
A rear axle center (RAC) locating system may include a tractor and a RAC location acquisition unit. The tractor may include a rear axle having a center, a global positioning system (GPS) antenna offset from the rear axle, and inertial measurement units. The RAC location acquisition unit may include a processing unit and a non-transitory computer-readable medium containing instructions to direct the processing unit to determine a geographic location of the GPS antenna based upon signals received by the GPS antenna and determine a geographic location of the center of the rear axle based upon the geographic location of the GPS antenna and combined data from the inertial measurement units.