Brake Pedal Stroke Control for Smooth Regenerative Deceleration
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Solution Overview
Problem
Drivers experience discomfort when operating the brake pedal in vehicles that generate deceleration through both accelerator and brake pedal operations, leading to inconsistent deceleration torque feelings.
Innovation Solution
A braking/driving force control method and device that adjusts brake pedal stroke based on accelerator pedal operation, utilizing regenerative braking and hydraulic actuator control to minimize frictional braking, optimizing deceleration torque generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If deceleration driving force is generated when accelerator pedal operation amount is small, then energy recovery efficiency is improved, but driver comfort deteriorates due to unexpected deceleration before brake pedal operation
Solution Approach 1:
The control device performs preliminary action by controlling the brake pedal to advance toward the accelerator pedal before the accelerator pedal reaches the release position. This preliminary movement of the brake pedal ensures that friction braking is ready to engage smoothly, preventing sudden deceleration and improving driver comfort while maintaining energy recovery efficiency through coordinated regenerative and friction braking.
2Measurement precision
If brake pedal operation is required for deceleration, then driver control precision is improved, but system complexity increases due to coordination of multiple braking mechanisms
Solution Approach 1:
The control device merges regenerative braking and friction braking into a unified control system. By integrating the control of the driving force source (regenerative braking) and the brake pedal (friction braking) into a single coordinated system, the patent achieves precise deceleration control while managing system complexity through unified management of multiple braking mechanisms.
Solution Approach 2:
The control device acts as an intermediary that coordinates between the driver's accelerator pedal input and the multiple braking mechanisms. It mediates the transition between acceleration and deceleration by automatically controlling the brake pedal position based on accelerator pedal position, providing precise deceleration control without requiring direct driver intervention in the braking system.
3Speed
If friction brake is used for deceleration, then deceleration response speed is improved, but energy loss increases due to non-regenerative braking
Solution Approach 1:
The control device implements periodic action by alternating between regenerative braking (when accelerator pedal is depressed) and friction braking (when accelerator pedal is released). This periodic switching between braking mechanisms ensures rapid deceleration response when needed while maximizing energy recovery during acceleration phases, thereby reducing overall energy loss.
Solution Approach 2:
The control device changes the parameter of braking mechanism selection based on accelerator pedal position. When the accelerator pedal operation amount exceeds a threshold, regenerative braking is used; when it falls below the threshold, friction braking is activated. This dynamic parameter change optimizes the balance between deceleration response speed and energy loss.
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
Reduces driver discomfort by smoothing deceleration torque transitions and enhances regenerative energy recovery efficiency.
Implementation Method 1
a hydraulic actuator that controls a brake pedal stroke amount
Implementation Method 2
by generating deceleration driving force when the operation amount of the accelerator pedal is smaller than a predetermined operation amount
Data Source
Figure 1
Figure 2~3B
Figure 4A~4F
AI summary
A braking/driving force control method includes detecting an accelerator stroke amount being the stroke amount of an accelerator pedal (S1), calculating a driving force to be generated by a vehicle driving force source when the accelerator stroke amount is larger than a predetermined first stroke amount (S3), calculating a deceleration driving force to be generated by the vehicle driving force source when the accelerator stroke amount is smaller than a second stroke amount set to a value smaller than or equal to the first stroke amount (S4), controlling the vehicle driving force source to generate the calculated driving force and deceleration driving force (S6), and generating a braking force on wheels according to a depressing operation of a brake pedal by a driver and controlling a brake stroke amount being the stroke amount of the brake pedal according to the calculated deceleration driving force (S5).