Crop-Row Steering Angle Limiting for Autonomous Work Vehicles
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Solution Overview
Problem
When a work vehicle performs self-traveling among crop rows in a field, there is a desire to reduce or prevent unwanted contact with the crop rows, which can lead to damage and affect driving stability.
Innovation Solution
A work vehicle equipped with wheels responsible for steering, a steering device, exterior sensors, and a controller that sets a maximum steering angle based on the vehicle's state and environment, detects crop rows, sets a target path, computes a target steering angle, limits it to the maximum steering angle if necessary, and controls the steering device to follow the target path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the work vehicle uses a large steering angle to navigate between crop rows, then the vehicle can follow the target path more accurately, but the vehicle may contact the crop rows causing damage and reducing driving stability
Solution Approach 1:
The maximum steering angle is not fixed but dynamically adjusted based on the detected distance to crop rows. When the distance sensor detects that the vehicle is close to crop rows, the maximum steering angle is reduced to prevent contact. This dynamic adjustment allows the vehicle to maintain high path following accuracy when safe, while ensuring driving stability when approaching crop rows.
Solution Approach 2:
The system continuously monitors the distance to crop rows using distance sensors and adjusts the maximum steering angle accordingly. This feedback mechanism ensures that the steering angle is optimized in real-time to balance path following accuracy with the prevention of crop row contact, thereby maintaining both measurement precision and reliability.
2Reliability
If the work vehicle reduces steering angle to avoid contacting crop rows, then driving stability is improved, but the vehicle's ability to follow the target path accurately is reduced
Solution Approach 1:
The maximum steering angle is dynamically adjusted based on real-time distance measurements. When the vehicle is far from crop rows, a larger steering angle is permitted to improve path following accuracy. When the vehicle approaches crop rows, the maximum steering angle is reduced to maintain driving stability. This dynamic adjustment resolves the contradiction by adapting the steering angle to the current operational context.
Solution Approach 2:
Different steering angle limits are applied in different spatial contexts. In areas where the distance to crop rows is large, larger steering angles are allowed for better path following. In areas where the distance is small, smaller steering angles are enforced to prevent contact. This local quality approach allows the system to optimize path following accuracy where safe while ensuring driving stability where needed.
3Productivity
If the work vehicle increases maximum steering angle for faster navigation, then productivity is improved, but the risk of contacting crop rows increases
Solution Approach 1:
The system uses distance sensors to continuously monitor the environment and provides feedback to the steering control system. This feedback enables the vehicle to use larger steering angles (improving productivity) when the distance to crop rows is sufficient, while automatically reducing the steering angle (preventing contact) when the distance becomes small. This resolves the contradiction between productivity and crop row contact risk.
Solution Approach 2:
The system proactively reduces the maximum steering angle before the vehicle actually contacts the crop rows. By detecting the distance in advance and adjusting the steering angle limit accordingly, the system prevents harmful contact while maintaining efficient navigation. This preliminary action approach allows the vehicle to optimize productivity without compromising crop safety.
Data Source
AI summary
A work vehicle includes wheels for steering, a steering device to change a steering angle of the wheels for steering, a sensor to output data indicating features around the work vehicle, and a controller to control self-traveling of the work vehicle, set a maximum steering angle for the wheels for steering based on a state of the work vehicle or its surrounding environment, detect two crop rows on opposite sides of the work vehicle based on the data, set a target path for the work vehicle in between the two crop rows, compute a target steering angle for the wheels for steering, limit the target steering angle to be equal to or smaller than a maximum steering angle when the computed target steering angle is greater than the maximum steering angle, and control the steering device so that the steering angle of the wheels for steering equals the target steering angle.