One-Pedal Drive Torque Control for Smooth Vehicle Stopping

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Solution Overview

Problem

In one pedal driving mode, vehicles lack an efficient method to control speed reduction and stopping without relying on friction brakes, especially when the accelerator pedal is released, leading to inconsistent braking experiences.

Innovation Solution

A controller-operated electric machine provides braking torque based on a predetermined speed versus time profile, increasing torque when the vehicle speed exceeds a target speed and decreasing torque when it falls below, allowing for smooth deceleration to zero without friction brakes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If regenerative braking is used without friction brakes in one pedal drive mode, then energy recovery is improved, but braking consistency and control precision deteriorate

Engineering Contradiction:

Improveenergy recoveryVSAvoidbraking consistency

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The controller continuously monitors vehicle speed and compares it against a predetermined speed profile, adjusting the regenerative braking torque in real-time based on the difference between actual and target speeds. This closed-loop feedback control ensures consistent stopping behavior while maximizing energy recovery.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system dynamically adjusts the regenerative braking torque throughout the deceleration process, transitioning from higher torque at higher speeds to lower torque as the vehicle approaches the target speed. This dynamic adjustment maintains braking consistency across varying conditions while optimizing energy recovery.

Inventive Principle:

Principle #15Dynamics

2Force

If regenerative braking torque is increased to improve stopping capability, then braking force is improved, but stopping precision deteriorates due to overshooting the target speed

Engineering Contradiction:

Improvebraking forceVSAvoidstopping precision

Core Design Contradiction:

ForceVSMeasurement precision

Solution Approach 1:

The controller periodically updates the braking torque commands based on the vehicle speed feedback, adjusting the torque in controlled increments rather than applying maximum torque continuously. This periodic adjustment prevents overshooting while maintaining effective braking force throughout the deceleration process.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The system changes the braking torque parameter dynamically based on the vehicle's current speed relative to the target speed profile. As the vehicle approaches the target speed, the controller reduces the torque magnitude to prevent overshooting, thereby achieving both sufficient braking force and precise stopping control.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If a predetermined speed profile is used to control deceleration, then stopping consistency is improved, but system complexity increases due to additional control logic

Engineering Contradiction:

Improvestopping consistencyVSAvoidcontrol logic complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The speed profile is predetermined and stored in the controller before deceleration begins. This preliminary preparation allows the controller to simply compare actual speed against the pre-calculated profile during deceleration, achieving consistent stopping behavior without requiring complex real-time calculations or additional hardware.

Inventive Principle:

Principle #10Preliminary action

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

This method enables consistent and controlled vehicle stopping from low speeds, maintaining similar stopping feel and distance on flat ground, utilizing regenerative braking to manage speed reduction effectively.

Implementation Method 1

releasing the accelerator pedal may cause the generator to regeneratively brake the vehicle

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

the electric machine provides braking torque according to a predetermined speed versus time profile

Methodology Applied

Scientific EffectElectromagnetic torque: Lorentz Force

Data Source

PatentUS11623629B2One-pedal drive method to control vehicle speed to a stop using feedback powertrain torque controls

Publication Date: 2023.04.11 FORD GLOBAL TECH LLC

AI summary

A controller, responsive to accelerator pedal release and a speed of the vehicle being less than a threshold, operates an electric machine to provide braking torque according to a predetermined speed versus time profile that defines a predetermined duration for the speed to become zero and a target speed for each time instant during the predetermined duration such that, for a given one of the time instants, the electric machine increases the braking torque responsive to the speed being greater than the target speed and decreases the braking torque responsive to the speed being less than the target speed.