Braking Force Controller Managing Negative Jerk

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Solution Overview

Problem

Existing vehicle braking systems fail to provide an appropriate deceleration feel and ride comfort during coasting states, as they do not effectively manage negative jerk, leading to shocks that deteriorate the riding experience.

Innovation Solution

A braking force controller that utilizes a combination of actuators, including a differential gear and an in-wheel motor, to calculate and generate target jerks, ensuring minimal shock and appropriate deceleration by distributing braking forces between actuators based on vehicle speed, drive mode, road gradient, and actuator conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If braking force is applied during coasting state, then deceleration feel is improved, but shock is generated due to negative jerk

Engineering Contradiction:

Improvedeceleration feelVSAvoidshock

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The braking force control is segmented into two independent control paths: one for the first actuator unit (engine braking) and one for the second actuator unit (regenerative braking). Each path calculates and controls braking force independently, allowing the system to manage negative jerk more effectively by coordinating these segmented control actions rather than applying braking force as a single unit.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The control system dynamically adjusts the braking force distribution between the first and second actuator units based on real-time vehicle conditions. The processor continuously monitors the coasting state and calculates optimal braking forces to achieve target deceleration while maintaining negative jerk within acceptable limits, making the system adaptive rather than static.

Inventive Principle:

Principle #15Dynamics

2Use of energy by moving object

If regenerative braking is used, then fuel efficiency is improved, but shock is generated due to sudden braking force

Engineering Contradiction:

Improvefuel efficiencyVSAvoidshock

Core Design Contradiction:

Use of energy by moving objectVSObject-affected harmful factors

Solution Approach 1:

The control system performs preliminary calculations of the required braking force and negative jerk characteristics before actual braking engagement. By pre-calculating the target braking force and considering the negative jerk constraints, the system prepares the optimal braking strategy in advance, allowing for smoother activation of regenerative braking without sudden shocks.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The control system implements feedback by continuously monitoring the actual braking force generated and comparing it with the target braking force. Based on this feedback, the processor adjusts the braking force distribution between engine braking and regenerative braking to maintain negative jerk within acceptable limits while maximizing energy recovery.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS11565669B2Braking force controller and vehicle

Publication Date: 2023.01.31 TOYOTA JIDOSHA KK

AI summary

A braking force controller causes a first actuator unit to generate a target jerk when the target jerk is equal to or larger than a first jerk, causes the first actuator unit to generate the first jerk and a second actuator unit to generate a jerk obtained by subtracting the first jerk from the target jerk as an additional jerk when the target jerk is smaller than the first jerk and equal to or larger than the sum of the first jerk and a second jerk, and causes the first actuator unit to generate the first jerk and the second actuator unit to generate the second jerk as the additional jerk when the target jerk is smaller than the sum of the first jerk and the second jerk.