Coasting Brake Force Allocation for Consistent Multi-Actuator Deceleration

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Solution Overview

Problem

Existing vehicle braking systems during coasting driving often fail to accurately match the expected braking force with the actual force generated, leading to inconsistencies and user dissatisfaction due to independent operation of actuators based on individual control system requests.

Innovation Solution

A vehicular braking force control system comprising a coasting state detection unit, a target braking force calculation unit, and a braking force distribution control unit that collectively manages multiple actuators to ensure the generated braking force aligns with user expectations by calculating and distributing forces within actuator limits, thereby achieving a consistent target braking force.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If actuators operate independently based on individual control system requests, then each actuator can be controlled by its own control system, but the actual braking force deviates from the target braking force and greatly fluctuates

Engineering Contradiction:
ImproveIndependent actuator controlVSAvoidBraking force consistency
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent merges multiple independent actuator control systems into a unified braking force distribution control system. The control device centrally manages multiple actuators (engine braking, regenerative braking, friction braking) that previously operated independently, coordinating their braking forces to achieve a consistent target braking force and eliminate fluctuations.

Inventive Principle:
Principle #5Merging (Combining)

2Manufacturing precision

If a target braking force is smoothly increased with vehicle speed, then the braking force profile is optimized for user expectation, but the actual braking force deviates due to independent actuator operation

Engineering Contradiction:
ImproveTarget braking force profile accuracyVSAvoidActual braking force measurement
Core Design Contradiction:
Manufacturing precisionVSMeasurement precision

Solution Approach 1:

The patent implements a feedback control mechanism where the control device continuously monitors the actual braking force generated by multiple actuators and compares it with the target braking force. Based on this feedback, the control device adjusts the distribution of braking forces among actuators to minimize the deviation and achieve the desired smooth braking force profile.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent dynamically adjusts the braking force distribution among multiple actuators based on real-time vehicle conditions and actuator capabilities. The control device continuously optimizes the braking force allocation to maintain consistency between target and actual braking forces, adapting to changing operating conditions such as vehicle speed and road surface gradient.

Inventive Principle:
Principle #15Dynamics

3Use of energy by moving object

If fuel cut is performed at 40 km/h boundary, then fuel economy is improved, but the braking force greatly fluctuates through the target braking force

Engineering Contradiction:
ImproveFuel consumption during coastingVSAvoidBraking force stability
Core Design Contradiction:
Use of energy by moving objectVSStability of the object's composition

Solution Approach 1:

The patent dynamically coordinates multiple braking actuators to compensate for the discontinuous braking force changes that occur during fuel cut operations. When fuel cut is activated at the 40 km/h boundary, the control device adjusts the distribution of braking forces among engine braking, regenerative braking, and friction braking to maintain stable total braking force and prevent fluctuations.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP3536569B1Braking force control system and method
Publication Date: 2023.10.18 TOYOTA JIDOSHA KK
  • EP3536569B1 patent drawingFigure 1
  • EP3536569B1 patent drawingFigure 2
  • EP3536569B1 patent drawingFigure 3~5

AI summary

A vehicular breaking force control system includes: a plurality of actuators capable of generating a braking force for a vehicle; a coasting state detection unit configured to detect that a coasting state has been established; a target braking force calculation unit configured to calculate a target braking force on the basis of a state of the vehicle when the coasting state detection unit detects that the coasting state has been established; and a braking force distribution control unit configured to determine a distribution braking force that is a braking force to be caused to be generated by each actuator, such that the distribution braking force is equal to or less than a braking force generable by the actuator and a sum of the distribution braking forces is equal to the target braking force, and to perform control of causing each actuator to generate the distribution braking force.