One-Pedal Launch Torque Control for Uphill Rollback Prevention

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Solution Overview

Problem

Electric vehicles in one-pedal driving mode face challenges in launching from a standstill without rollback on uphill grades due to insufficient propulsion torque, as existing systems rely on driver input or immediate brake release, which can lead to unintended vehicle movement.

Innovation Solution

A vehicle controller programmed to automatically engage and release friction brakes based on estimated wheel torque exceeding a grade-compensation torque threshold, ensuring smooth launch without rollback by coordinating electric machine propulsion and regenerative braking.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the friction brakes are released immediately when the vehicle is stationary in one-pedal mode, then the vehicle can respond quickly to acceleration requests, but the vehicle may experience rollback on uphill grades due to insufficient propulsion torque

Engineering Contradiction:

Improvevehicle response speedVSAvoidlaunch reliability on uphill grades

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The system performs preliminary action by delaying brake release until the electric machine generates sufficient propulsion torque to overcome the grade-compensation torque threshold. This ensures the vehicle has adequate force ready before the brakes are released, preventing rollback while maintaining ready-to-launch capability.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The controller continuously monitors the estimated propulsion torque and compares it against the grade-compensation torque threshold. This feedback mechanism ensures brakes are released at the optimal moment when sufficient torque is available, resolving the contradiction between quick response and reliable launch on grades.

Inventive Principle:

Principle #23Feedback

2Reliability

If the friction brakes are held until sufficient propulsion torque is achieved, then rollback is prevented on uphill grades, but the vehicle launch response time is delayed

Engineering Contradiction:

Improvelaunch reliability on uphill gradesVSAvoidvehicle launch response time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The system dynamically adjusts the brake release timing based on real-time torque conditions. Rather than using a fixed delay, the controller monitors propulsion torque continuously and releases brakes as soon as the torque exceeds the grade-compensation threshold, optimizing both reliability and response time.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The electric machine serves itself by generating the necessary propulsion torque to enable brake release. The system uses its own propulsion capability to determine when it is ready for launch, eliminating the need for external timing mechanisms or driver input.

Inventive Principle:

Principle #25Self-service

3Use of energy by moving object

If the vehicle uses only regenerative braking to hold the vehicle stationary, then the battery is recharged, but the vehicle cannot maintain position on uphill grades without friction brake engagement

Engineering Contradiction:

Improveregenerative braking energy recoveryVSAvoidstationary holding capability on grades

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The system merges regenerative braking with friction braking to achieve reliable stationary holding on uphill grades. The friction brakes provide the necessary mechanical holding force, while regenerative braking can contribute additional force when available, creating a combined braking system that overcomes the limitations of either system alone.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The friction brakes act as an intermediary mechanism that bridges the gap between regenerative braking capability and the actual force needed to hold the vehicle on grades. This intermediary system ensures reliable stationary holding while allowing regenerative braking to contribute when possible.

Inventive Principle:

Principle #24Intermediary (Mediator)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enables reliable and smooth vehicle launch from standstill in one-pedal mode on uphill grades by delaying brake release until sufficient propulsion torque is achieved, preventing rollback and enhancing driver convenience.

Implementation Method 1

an electric machine configured to power driven wheels

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

friction brakes

Methodology Applied

Scientific EffectFriction: Friction

Implementation Method 3

capable of regenerative braking to recharge the battery by converting mechanical power into electrical power

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS20220080971A1Uphill vehicle launch in one-pedal driving mode

Publication Date: 2022.03.17 FORD GLOBAL TECH LLC

AI summary

A vehicle includes a powertrain having an electric machine configured to power driven wheels and friction brakes. A vehicle controller is programmed to, with the vehicle being in a one-pedal driving mode and the friction brakes automatically engaged to hold the vehicle stationary, release the friction brakes absent input from a brake pedal in response to an estimated torque of the driven wheels exceeding a grade-compensation torque threshold that is based on road grade to launch the vehicle without rollback.