Vehicle Launch Assist Torque Constraints for Slip Prevention
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Solution Overview
Problem
Existing vehicle control systems fail to effectively prevent excessive wheel slip during vehicle launch on low-friction surfaces like sand, as they rely on torque control systems that may not intervene promptly enough to prevent wheels from sinking into the surface.
Innovation Solution
A Vehicle Launch Assist (VLA) function is implemented, which activates a set of constraints on torque applied to the wheels based on terrain-specific data, including tyre pressure and surface characteristics, to prevent excessive wheel slip by limiting powertrain torque and response to driver demand.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a vehicle slip control system is used to reduce wheel slip, then wheel slip can be reduced, but the system cannot intervene when vehicle speed is below a threshold speed
Solution Approach 1:
The VLA function performs preliminary action by imposing torque constraints before wheel slip can occur during vehicle launch. The system proactively limits powertrain torque based on terrain-specific data and tyre pressure information, preventing excessive wheel slip from occurring in the first place, rather than reacting after slip is detected.
Solution Approach 2:
The VLA function acts as an intermediary system that bridges the gap between the powertrain and the slip control system. It imposes intermediate torque constraints that work in conjunction with the slip control system, allowing effective wheel slip prevention at low speeds where the slip control system alone cannot intervene.
2Speed
If torque is increased to improve acceleration, then acceleration performance improves, but excessive wheel slip occurs on low-friction surfaces
Solution Approach 1:
The system dynamically changes torque parameters based on operating conditions. The VLA function adjusts the maximum allowable powertrain torque according to tyre pressure data and terrain characteristics, optimizing the balance between acceleration performance and wheel slip prevention for specific surface conditions.
Solution Approach 2:
The torque constraint imposed by the VLA function is dynamic rather than static. The system continuously monitors vehicle speed, tyre pressure, and terrain conditions, adjusting the torque limit in real-time to maintain optimal acceleration while preventing wheel slip as conditions change during vehicle launch.
3Object-affected harmful factors
If torque constraints are imposed to prevent wheel slip, then wheel spin is reduced, but acceleration performance is reduced
Solution Approach 1:
The VLA function applies localized torque constraints specific to the launch condition rather than globally limiting torque in all operating conditions. The system uses terrain-specific data and tyre pressure information to impose appropriate constraints only when needed during vehicle launch, maintaining acceleration performance in other operating conditions.
Solution Approach 2:
The system applies partial torque constraints rather than completely limiting powertrain torque. The VLA function imposes only the necessary torque limit to prevent wheel spin during launch, allowing the vehicle to still achieve acceptable acceleration performance while preventing the harmful effect of excessive wheel spin on low-friction surfaces.
Data Source
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AI summary
The present invention relates to a vehicle control system for at least one vehicle subsystem of a vehicle, the system being operable to activate a vehicle launch assist (VLA) function to prevent excessive wheel slip, when the launch assist function is active the system being configured to impose a set of one or more prescribed constraints on an amount of torque applied to one or more wheels of a vehicle, wherein the set of one or more constraints are determined by reference to information or data in respect of an amount of wheel torque that may be applied before the amount of wheel slip exceeds a prescribed value.