Trailer Backup Assist Selectable Hitch Angle Limits
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Solution Overview
Problem
Backing up a vehicle with a trailer is challenging due to the need for counter-steering and braking to prevent jack-knifing, and small steering errors amplify, causing the trailer to deviate from the desired path, especially for infrequent drivers.
Innovation Solution
A trailer backup assist system with normal and advanced modes that limits steering commands based on calculated angle limits, allowing drivers to select modes through a user interface and adjust limits, using sensors to monitor hitch angle and trailer dynamics for precise control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the steering command allows maximum controllable angle for tighter turns, then the turning capability is improved, but the risk of jack-knifing and trailer deviation increases
Solution Approach 1:
The system dynamically adjusts the steering angle limit based on operating conditions. In advanced mode, the system permits steering commands up to the maximum controllable angle (first angle limit) when conditions allow, but automatically applies a more conservative second angle limit when the trailer approaches unstable hitch angles, thus adapting the control strategy to real-time conditions to prevent jack-knifing while maximizing turning capability when safe
Solution Approach 2:
The system continuously monitors the hitch angle and trailer dynamics through sensors, providing real-time feedback to the controller. This feedback mechanism allows the system to detect when the trailer is approaching unstable conditions and automatically restricts steering commands to the second angle limit, preventing jack-knifing while informing the driver through the human-machine interface of the current angle limit being applied
2Reliability
If a conservative angle limit is used to prevent jack-knifing, then safety is improved, but the turning capability and maneuverability are reduced
Solution Approach 1:
The system transitions between two distinct operating modes: normal mode applies the conservative second angle limit for safety, while advanced mode allows the maximum first angle limit for enhanced turning capability. The system dynamically switches between these modes based on real-time hitch angle monitoring, providing safety when needed and maximum capability when conditions permit
Solution Approach 2:
The system changes the steering angle limit parameter based on operating conditions and user selection. The controller can apply either the first angle limit (maximum controllable angle for tight turns) or the second angle limit (conservative limit for stability), switching between these parameter values to balance safety and turning capability according to the current situation
3Ease of operation
If the system provides simple automated control, then ease of use is improved, but the ability to handle complex maneuvers is reduced
Solution Approach 1:
The control system is segmented into two distinct modes: normal mode for simplified automated control that prioritizes ease of use with conservative angle limits, and advanced mode for experienced users who need maximum turning capability and can handle complex maneuvers. This segmentation allows the system to cater to different user skill levels and maneuver requirements without compromising either simplicity or capability
4Ease of operation
If the system allows maximum steering input for tight turns, then the turn radius is reduced, but the trailer path accuracy deteriorates
Solution Approach 1:
The system uses real-time feedback from hitch angle sensors to monitor trailer response to steering commands. When maximum steering input is applied in advanced mode, the feedback mechanism detects hitch angle changes and automatically applies the conservative second angle limit if the trailer begins to deviate from the desired path, thus maintaining path accuracy even when tight turns are initiated
Solution Approach 2:
The system takes preliminary anti-action by preemptively applying angle limits before jack-knifing or significant deviation can occur. The controller continuously calculates the risk of unstable conditions and restricts steering commands to prevent the trailer from entering problematic states, countering potential path accuracy deterioration before it happens
Data Source
AI summary
A backup assist system for a vehicle reversing a trailer includes a controller receiving a driver control signal and outputting a vehicle backing steering command based on the control signal and limited by one of a first angle limit corresponding with a calculated maximum controllable angle and a second angle limit at a maneuverability threshold below the maximum controllable angle. The system further includes an interface outputting an indication of the one of the first and second angle limits.