Regenerative Torque Control for Natural Motorcycle Braking Feel

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Solution Overview

Problem

Existing electric vehicle regeneration control systems fail to replicate the braking feeling intended by the user, leading to discomfort for drivers familiar with internal combustion engine vehicles, as they do not effectively adjust regenerative torque based on user input.

Innovation Solution

A regeneration control method that determines the required regenerative torque for an electric motor by analyzing the degree of decrease in the accelerator operation amount over time, using a processing circuitry to switch between normal and strong regenerative torque maps, ensuring the regenerative torque matches the user's intended braking force.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If regenerative braking control is performed in electric vehicles, then energy recovery efficiency is improved, but braking feeling comfort deteriorates

Engineering Contradiction:
Improveenergy recovery efficiencyVSAvoidbraking feeling comfort
Core Design Contradiction:
Loss of energyVSEase of operation

Solution Approach 1:

The patent applies dynamics by making the regenerative braking torque adjustable and time-dependent. The control system dynamically modifies the torque characteristics based on the vehicle's operational state and temporal factors, transitioning from a static torque application to a dynamic one that adapts to driver expectations and vehicle conditions, thereby improving both energy recovery and braking comfort

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the parameter of regenerative braking torque magnitude over time. By implementing a time-based torque reduction strategy where the regenerative torque is gradually decreased after initial application, the system maintains effective energy recovery while adapting the braking sensation to match driver expectations, thus resolving the contradiction between energy efficiency and comfort

Inventive Principle:
Principle #35Parameter changes

2Productivity

If regenerative torque is increased to improve energy recovery, then productivity is improved, but driver comfort deteriorates

Engineering Contradiction:
Improveenergy recoveryVSAvoiddriver discomfort
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent implements periodic action through time-based torque modulation. The regenerative braking torque is applied in a structured temporal sequence: initially at a higher level to maximize energy recovery, then gradually reduced over a predetermined time period. This periodic modulation allows the system to capture maximum energy while preventing sustained high torque that would cause driver discomfort

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The patent applies beforehand cushioning by pre-planning the torque reduction schedule. The control system anticipates potential driver discomfort from sustained high regenerative torque and proactively reduces the torque after an initial period, cushioning the driver from the harmful effects of excessive or prolonged regenerative braking while maintaining overall energy recovery efficiency

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

Data Source

PatentEP4477451A1Regeneration control method and straddle-type vehicle
Publication Date: 2024.12.18 KAWASAKI MOTORS LTD
  • EP4477451A1 patent drawingFigure 1
  • EP4477451A1 patent drawingFigure 2
  • EP4477451A1 patent drawingFigure 3

AI summary

There are provided a regeneration control method for a vehicle and a straddle-type vehicle which is an example of the vehicle. The regeneration control method is executed in a processing circuitry of the vehicle including an electric motor as a drive source, and the regeneration control method includes: determining whether a start condition of regeneration control for requesting the electric motor to generate a regenerative torque is satisfied; acquiring a degree of decrease in an accelerator operation amount with lapse of time before start of the regeneration control; and determining a required regenerative torque, which is the regenerative torque required for the electric motor, based on the degree of decrease in the accelerator operation amount.