Vehicle Speed Control System Wheel Slip Handling
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Solution Overview
Problem
Existing vehicle speed control systems, such as cruise control, are ineffective in low-speed conditions and off-road terrains due to cancellation upon wheel slip events, making them unreliable for maintaining progress in adverse conditions like slippery or icy surfaces.
Innovation Solution
A vehicle speed control system that temporarily suspends acceleration when a wheel slip event is detected, maintaining the current speed until the slip event ceases, and resumes acceleration at a limited rate when conditions are favorable, allowing the vehicle to maintain a set speed without user intervention in challenging terrains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If cruise control systems are designed to operate only above a certain speed (15-20mph), then high-speed highway driving is improved, but low-speed off-road progress is prevented
Solution Approach 1:
The system dynamically adjusts its operational characteristics based on detected driving conditions. The speed control system transitions between different control modes (cruise control for high-speed, progress control for low-speed) depending on whether the vehicle is operating above or below the threshold speed, allowing it to adapt to both highway and off-road conditions effectively
Solution Approach 2:
The control system is designed to perform multiple functions across different operating ranges. By integrating both cruise control and progress control capabilities within a single system that can operate across the entire speed range (both above and below 15-20mph), the system achieves versatility across different driving conditions including highway, congested traffic, and off-road terrains
2Reliability
If cruise control systems are disabled upon wheel slip detection, then safety is improved, but off-road progress capability is reduced
Solution Approach 1:
The control system is segmented into distinct functional modes: cruise control mode for high-speed operation where cancellation on slip is appropriate, and progress control mode for low-speed off-road operation where continued operation during slip is beneficial. This segmentation allows each mode to be optimized for its specific operating conditions without compromising the other
Solution Approach 2:
The system changes its operational parameters based on the detected driving conditions. When operating below the threshold speed in off-road conditions, the system modifies its response to wheel slip events by continuing to provide speed control rather than cancelling, thereby maintaining productivity while still ensuring safety through appropriate parameter adjustment
3Productivity
If acceleration is continuously applied to reach target speed, then productivity is improved, but wheel slip and surface degradation increase
Solution Approach 1:
The system continuously monitors wheel slip conditions and uses this feedback to modulate acceleration. When wheel slip is detected during acceleration, the system reduces or suspends further acceleration temporarily, then resumes at a limited rate once conditions improve. This closed-loop feedback control balances productivity with prevention of harmful wheel slip and surface degradation
Data Source
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AI summary
A vehicle speed control system for a vehicle having a plurality of wheels, the vehicle speed control system comprising: means for receiving a user input of a target speed at which the vehicle is intended to travel; and means for commanding application of torque to one or more wheels of the vehicle, wherein the system is configured such that when it is required to accelerate the vehicle to achieve the target speed and the system detects a wheel slip event, the system is operable temporarily to suspend further acceleration of the vehicle.