Dynamic Wheel Slip Control for Multi-Motor EV Torque Bias

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Solution Overview

Problem

Conventional four-wheel vehicles with four-wheel drive systems suffer from driveline windup, crow hop, and poor responsiveness due to mechanical lockers forcing all wheels to rotate at the same speed, regardless of steering input or terrain variation, and reactive brake-based solutions offer poor performance.

Innovation Solution

A dynamic slip target control system using multiple electric motors to independently control wheel slip based on steering angle and vehicle speed, calculating an expected differential speed and enforcing it, allowing for enhanced grip and yaw control without locking components, using a PID controller for aggressive tuning.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If mechanical lockers are used to force equal wheel speed, then wheel/tire grip performance is improved, but driveline windup and poor responsiveness occur

Engineering Contradiction:

Improvewheel/tire grip performanceVSAvoidsteering responsiveness

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent replaces mechanical lockers with an electronic control system that uses multiple independent motors and a controller to manage wheel slip dynamically. This substitution eliminates the mechanical constraints that caused driveline windup while maintaining grip through active control of differential wheel speeds based on steering angle and vehicle speed sensors.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system dynamically adjusts wheel slip targets based on real-time sensor inputs (steering angle, vehicle speed, wheel speed) rather than forcing fixed equal-speed operation. The controller continuously modifies torque distribution to achieve desired trajectory tracking while adapting to changing driving conditions, thereby maintaining both grip and steering responsiveness.

Inventive Principle:

Principle #15Dynamics

2Power

If mechanical lockers force equal speed distribution, then torque distribution is improved, but driveline binding and crow hop occur

Engineering Contradiction:

Improvetorque distributionVSAvoiddriveline binding

Core Design Contradiction:

PowerVSObject-generated harmful factors

Solution Approach 1:

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system changes the operational parameters from fixed equal-speed distribution to dynamic speed differential distribution. The controller calculates target wheel slip values and adjusts motor torque outputs based on actual wheel speeds and steering conditions, allowing torque to be distributed optimally without forcing equal speeds that cause binding.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If reactive brake-based solutions are used to control wheel spin, then wheel slip control is achieved, but performance is poor

Engineering Contradiction:

Improvewheel slip controlVSAvoidcontrol performance

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The system performs preliminary action by proactively controlling wheel slip through motor torque management before excessive wheel spin occurs. Rather than reacting to wheel spin with brakes, the controller prevents it by adjusting torque distribution in real-time based on predicted wheel slip targets, achieving superior control performance.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent replaces reactive brake-based control with proactive motor torque control. The electronic system manages wheel slip by adjusting motor outputs rather than applying brakes, providing more precise and responsive control performance.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Reliability

If multiple independent motors are used for independent wheel control, then grip and yaw control are improved, but device complexity increases

Engineering Contradiction:

Improvegrip and yaw controlVSAvoidpowertrain complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The controller performs multiple functions including trajectory tracking, wheel slip control, torque distribution, and steering assistance using a single integrated electronic control system. This multi-functionality achieves improved grip and yaw control without proportionally increasing overall system complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS12515535B2Techniques for dynamic wheel slip target control in multi-motor electrified vehicles

Publication Date: 2026.01.06 FCA US LLC

AI summary

Dynamic slip target control systems and method for a multi-motor electrified powertrain of an electrified vehicle including a driveline having four wheels involve determining (i) a steering angle of the driveline of the electrified vehicle, (ii) a vehicle speed of the electrified vehicle, and (iii) a wheel speed of each the four wheels of the driveline, dynamically determining a target wheel slip based on a wheel speed model with inputs including the steering angle and vehicle speed, determining an expected differential speed based on the dynamically determined target wheel slip, determining a torque bias adjustment based on a difference between wheel speed errors and the expected differential speed, and controlling two or more electric motors of the multi-motor electrified powertrain based on an estimated torque bias and the torque bias adjustment.