Off-Road Speed Control With Wheel Slip Torque Modulation
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Solution Overview
Problem
Existing vehicle speed control systems are ineffective in off-road conditions, particularly at low speeds, as they often require user intervention and are disabled by wheel slip events, and have minimum speed requirements that hinder progress in varied terrains.
Innovation Solution
A control system that automatically adjusts vehicle speed based on a target set-speed and terrain conditions, using a lookup table to determine incremental values for torque application, allowing continuous speed control without user intervention and managing wheel slip to maintain progress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cruise control systems are set with a minimum speed requirement to reduce low speed collision risk, then safety is improved, but the system becomes ineffective in low speed off-road conditions
Solution Approach 1:
The system dynamically adjusts the minimum speed threshold based on detected terrain conditions. On off-road terrain, the system allows operation below the standard 15mph threshold, while maintaining the threshold on road surfaces to prevent collisions. This dynamic adaptation resolves the contradiction by making the speed requirement flexible rather than fixed.
Solution Approach 2:
The system changes the operational parameters of the cruise control by modifying the minimum speed threshold parameter according to terrain type. The parameter is set to a higher value (15mph) for road conditions to ensure safety, and lowered or disabled for off-road conditions to enable progress, thus resolving the contradiction through parameter adaptation.
2Reliability
If cruise control systems cancel speed control upon detection of wheel slip events, then traction control is improved, but continuous speed control is lost in off-road conditions
Solution Approach 1:
The system uses feedback from wheel slip detection to modulate torque application rather than cancelling speed control. When wheel slip is detected, the system reduces torque to regain traction, then resumes speed control once traction is restored. This continuous feedback loop maintains both traction control and automated speed control simultaneously.
Solution Approach 2:
The control system acts as an intermediary between the wheel slip event and the speed control function. Instead of allowing wheel slip to directly cancel speed control, the system mediates by adjusting torque as an intermediate action, thereby maintaining continuous speed control while still addressing the traction issue.
3Productivity
If torque is applied to propel the vehicle at target speed, then progress is improved, but wheel slip events occur in varied terrain
Solution Approach 1:
The system applies torque in a periodic modulation pattern rather than continuously. When wheel slip is detected, torque is reduced or interrupted, then restored when traction improves. This periodic adjustment of torque maintains progress while preventing sustained wheel slip, resolving the contradiction between productivity and traction stability.
Solution Approach 2:
The torque application is dynamically adjusted based on real-time terrain conditions and wheel slip detection. The system increases torque to maintain progress when traction is good, and reduces torque when slip occurs, creating a dynamic response that balances productivity and traction stability according to current conditions.
Data Source
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AI summary
The present invention relates to a control system for a vehicle having a plurality of wheels, the control system is configured to automatically control the speed of the vehicle in dependence on an input target set-speed. The system comprises receiving means for receiving a user input of a target set-speed at which the vehicle is intended to travel comprising an input means to enable the user to incrementally increase and/or decrease the target set-speed upon each actuation of said input means by an incremental value. Applying means are provided for applying torque to the at least one of the plurality of wheels for propelling the vehicle at the vehicle control speed. The control system is configured to determine said incremental value in dependence upon said at least one of: the instantaneous vehicle speed; the target set-speed; or the terrain over which the vehicle is travelling.