Steer-by-Wire Torque Vectoring with Slip-Limited Speed Control

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Solution Overview

Problem

Existing steer-by-wire steering systems fail to effectively prevent wheel slipping during unstable driving situations, leading to undesirable tire wear and reduced driving dynamics and safety.

Innovation Solution

A steer-by-wire steering system with a single wheel drive on the front axle, controlled by a drive controller that sets target speeds for each wheel to minimize the difference between target and actual speeds, limiting slip to a predefined range, thereby preventing wheel spinning and maintaining traction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If torque vectoring is applied to counteract understeering or oversteering, then vehicle stability is improved, but wheel slipping cannot be effectively prevented

Engineering Contradiction:

Improvevehicle stabilityVSAvoidwheel slip prevention

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The system segments the drive torque control by independently controlling each wheel through separate wheel drives (10, 100) on the front axle. The drive controller (11) calculates individual target speeds for left and right wheels based on steering angle and vehicle speed, enabling independent torque application to each wheel to prevent slip while maintaining stability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system dynamically changes the torque parameters applied to each wheel based on real-time operating conditions. The drive controller adjusts target wheel speeds as a function of steering angle (βs) and vehicle speed (vFZ), modifying drive torques to minimize slip while maintaining vehicle stability during torque vectoring operations.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If wheel spinning is not controlled, then driving dynamics are reduced, but tire wear increases

Engineering Contradiction:

Improvedriving dynamicsVSAvoidtire wear

Core Design Contradiction:

ProductivityVSLoss of substance

Solution Approach 1:

The system implements feedback control by continuously monitoring actual wheel speeds and comparing them to target speeds calculated by the drive controller. The controller adjusts drive torques based on the difference between target and actual speeds, providing feedback control that minimizes slip (improving driving dynamics) while preventing excessive wheel spinning (reducing tire wear).

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS11505245B2Steer-by-wire steering system with torque vectoring and integrated anti-slip control

Publication Date: 2022.11.22 THYSSENKRUPP PRESTA AG

AI summary

A steer-by-wire steering system for a motor vehicle with a steerable front wheel axle that has two steerable wheels. The front wheel axle includes a single wheel drive which, by means of a drive controller, individually drives wheel drives which are associated with the steerable wheels. The drive controller has a controller which determines a target speed for the left-hand wheel and a target speed for the right-hand wheel in accordance with an accelerator pedal angle and a rotational angle of a steering shaft, and which limits the target speeds to a slip-limited speed. The drive controller individually drives the wheel drives in such a way that the difference between the target speed and the actual speed for each steerable wheel is minimal.