Trailer Hitch Angle Offset Estimation and Jackknife Prevention
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Solution Overview
Problem
Reversing a vehicle while towing a trailer is challenging due to the need for opposite steering inputs and amplified steering errors, and existing trailer backup assist systems are complex and costly, assuming a straight path and requiring complex human-machine interfaces and sensors to prevent jackknife conditions.
Innovation Solution
A method and system for estimating the actual hitch angle between a vehicle and a trailer using sensors and a controller, allowing for intuitive path curvature control through a user-friendly interface, such as a steering knob, and implementing countermeasures to prevent jackknife conditions by monitoring hitch angle and vehicle parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a trailer backup assist system assumes a straight path (zero curvature), then the system complexity is reduced, but the system cannot accommodate real-world curved path requirements
Solution Approach 1:
The system dynamically determines path curvature based on real-time sensor data (GPS coordinates, odometer readings, compass headings) rather than assuming a fixed straight path. The curvature calculation adapts to the actual driving conditions and user intentions, allowing the system to handle both straight and curved paths seamlessly.
Solution Approach 2:
The system continuously monitors vehicle position, speed, and orientation through sensors and uses this feedback to calculate the desired path curvature. This closed-loop approach allows the system to adjust its path assumptions based on actual driving behavior, improving both accuracy and adaptability without significantly increasing complexity.
2Measurement precision
If complex sensors (cameras, inertial navigation, high precision GPS) are used to determine desired path and detect jackknife conditions, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The system uses a multi-functional sensor suite where GPS provides both position information for path curvature calculation and reference points for jackknife detection. The same sensors serve multiple purposes: determining desired path, monitoring actual path, and detecting jackknife conditions, thereby reducing overall system complexity while maintaining precision.
Solution Approach 2:
The system introduces an intermediary calculation layer that processes data from simple sensors (GPS coordinates, odometer, compass) to derive complex information such as path curvature and jackknife risk assessment. This mathematical intermediary approach avoids the need for expensive dedicated sensors while achieving comparable measurement precision.
3Measurement precision
If a hitch sensor is used to measure hitch angle, then measurement capability is provided, but measurement precision is insufficient due to offset errors between measured and actual hitch angles
Solution Approach 1:
The system continuously monitors the relationship between steering angle and hitch angle through feedback from sensors. By analyzing how changes in steering angle correlate with changes in hitch angle during normal operation, the system can dynamically determine and compensate for offset errors, improving measurement precision without adding complex measurement hardware.
Solution Approach 2:
The system uses its own operational data (steering inputs, vehicle motion, sensor readings) to self-calibrate and determine the offset between measured and actual hitch angles. This self-service approach eliminates the need for external calibration equipment or more expensive dedicated hitch angle sensors.
4Reliability
If opposite steering inputs are required when backing a trailer, then jackknife prevention is achieved, but ease of operation deteriorates for unskilled drivers
Solution Approach 1:
The system replaces the need for driver skill and manual judgment with an automated electronic control system that monitors hitch angle, vehicle speed, and steering input. When jackknife conditions are detected or predicted, the system automatically applies countermeasures such as adjusting steering angle or reducing vehicle speed, eliminating the need for drivers to learn complex opposite-steering techniques.
Solution Approach 2:
The system proactively detects conditions that could lead to jackknife (such as excessive hitch angle combined with high reverse speed) and applies countermeasures before the jackknife condition fully develops. This preliminary anti-action approach prevents jackknife while maintaining simple, intuitive steering operation for the driver.
Data Source
AI summary
A system and a method are provided for estimating an actual hitch angle between a vehicle and a trailer. A hitch sensor on the vehicle continuously senses a measured hitch angle and a steering sensor continuously senses a steering angle of steered wheels of the vehicle. A controller determines an offset between the measured hitch angle and the actual hitch angle when the measured hitch angle and the steering angle are substantially constant while the vehicle and trailer are reversing.