Work Vehicle GNSS Antenna Layout for Accurate Low-Speed Auto Steering
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Solution Overview
Problem
Work vehicles face challenges in maintaining high accuracy for automatic travel on diverse work sites due to noise interference from structures like metal poles and wires, and difficulties in calculating orientation during low-speed turns with single GPS antennas or inertial measurement devices.
Innovation Solution
A work vehicle equipped with multiple positioning antennas and a positioning unit that calculates current position and orientation using a satellite positioning system, with a determination unit ensuring high-accuracy positioning states before initiating automatic travel, allowing for accurate navigation regardless of site conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single mobile GPS antenna is used for position measurement, then the device complexity is reduced, but the measurement precision of vehicle body position and orientation deteriorates
Solution Approach 1:
The patent divides the single antenna system into multiple segmented antennas (front antenna and rear antenna) positioned at different locations on the vehicle body. This segmentation allows the system to calculate both position and orientation by measuring signals at multiple points, thereby improving measurement precision while maintaining manageable device complexity.
Solution Approach 2:
The patent transitions from a single-point measurement (single antenna) to a multi-point spatial measurement system. By adding the dimensional aspect of spatial distribution with multiple antennas, the system can derive both position and orientation information, enhancing measurement precision without excessive complexity increase.
2Device complexity
If a geomagnetic sensor is used for orientation detection, then the device complexity is reduced, but the measurement precision deteriorates in environments with metal structures
Solution Approach 1:
The patent uses GPS signal measurements at multiple antenna positions as an intermediary method to calculate orientation. Instead of directly measuring magnetic field orientation with a geomagnetic sensor, the system indirectly derives orientation from positional differences between multiple GPS antennas, avoiding interference from metal structures while maintaining reasonable device complexity.
3Measurement precision
If an inertial measurement device is used for orientation measurement, then the measurement precision is improved, but the device complexity and cost increase
Solution Approach 1:
The patent extracts the orientation measurement function from dedicated inertial sensors and implements it through GPS signal processing. By taking out the orientation detection task from the sensor suite and solving it through computational methods using existing GPS antennas, the system achieves improved orientation precision without adding complex inertial measurement devices.
4Adaptability or versatility
If the vehicle turns at low speed, then the adaptability to various travel states is improved, but the measurement precision of orientation deteriorates due to small sensor output values
Solution Approach 1:
The patent compensates for the weakness of inertial sensors at low speeds by introducing GPS-based orientation calculation as a counterbalancing method. The GPS-derived orientation serves as a counterweight to the insufficient signal from inertial sensors during low-speed turns, maintaining measurement precision across diverse travel states without requiring excessive system complexity.
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 the work vehicle to travel accurately along a target path even in complex environments and during low-speed turns by using multiple antennas and inertial measurement, ensuring reliable automatic travel control.
Implementation Method 1
a positioning unit that uses a satellite positioning system to measure current position and current orientation of a vehicle body
Data Source
AI summary
This work vehicle has: a positioning unit for measuring the current position and the current direction of the vehicle body using a satellite positioning system; and an automatic travel control unit for executing automatic travel control based on positioning information from the positioning unit. The positioning unit comprises: a plurality of positioning antennas provided on the vehicle body; a plurality of positioning units for measuring the positions of the positioning antennas; a calculation unit for calculating the current position and the current direction of the vehicle body on the basis of positioning information from the positioning units; and a positioning state determination unit for determining whether or not the positioning state of the positioning units is a high-accuracy positioning state. When at least two positioning units are in the high accuracy positioning state, the positioning state determination unit permits the start of the automatic travel control.