AVH Release Control for Smooth Vehicle Launch
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Solution Overview
Problem
The existing Automatic Vehicle Hold (AVH) systems cause driver fatigue and uncomfortable vehicle start experiences due to the difficulty in precisely matching torque generation with braking force extinction, leading to feelings of being caught or rushing, especially on steep roads.
Innovation Solution
A method that allows drivers to select between two modes for releasing the AVH function: one by increasing power train torque via the accelerator pedal and another by releasing braking hydraulic pressure via the brake pedal, with the latter ensuring torque is maintained at or below creep torque levels, and includes visual or audible alarms for perception and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the AVH function is released by increasing power train torque through accelerator pedal depression, then the vehicle can start smoothly, but it causes driver fatigue due to the need to continue depressing the brake pedal in long-time stopping states
Solution Approach 1:
The AVH system automatically maintains vehicle stop state without requiring continuous driver input. The system self-regulates by maintaining brake pressure through the hold controller, eliminating the need for the driver to continuously depress the brake pedal, thus preventing driver fatigue while maintaining ease of operation
2Ease of operation
If the AVH function is released by matching torque generation with braking force extinction, then vehicle start control can be improved, but it causes feeling of being caught or rushing due to difficulty in precisely matching torque generation with braking force extinction
Solution Approach 1:
The system performs preliminary action by pre-releasing brake pressure before torque generation is complete. The release controller initiates brake pressure reduction in advance, creating a buffer that ensures smooth transition to motion without sudden jerks or rushing sensations, thereby improving start reliability
Solution Approach 2:
The system uses feedback from sensors monitoring brake pressure, torque generation, and vehicle motion to dynamically adjust the release profile. The release controller continuously receives feedback and modifies brake pressure reduction rate to match actual vehicle conditions, preventing feeling of being caught or rushing while maintaining smooth starts
3Stability of the object's composition
If the AVH function is released on steep roads by coordinating brake release with torque generation, then vehicle stability can be maintained, but it causes uncomfortable start feelings due to coordination difficulties between brake release and torque generation
Solution Approach 1:
The release controller acts as an intermediary between the brake system and power train, mediating the transition from stop to motion. It coordinates brake pressure release with torque generation by introducing a controlled delay and ramping the pressure reduction, which smooths the transition and eliminates uncomfortable start feelings while maintaining vehicle stability on steep roads
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 approach enhances driver convenience by allowing selection of release modes based on driving conditions, minimizing uncomfortable start feelings and ensuring safe vehicle launches, particularly on inclined roads.
Implementation Method 1
releasing hydraulic pressure of the brake without raising torque of the power train
Implementation Method 2
increase in torque of a power train by depressing an accelerator pedal
Implementation Method 3
distribution of friction force between frictional materials and disks of a brake system
Data Source
AI summary
A method of releasing an Automatic Vehicle Hold (AVH) function of an automotive vehicle equipped with a pedal simulator is provided. During operation of the AVH function, either a first mode for releasing the AVH function by an increase of torque of a power train by depressing the accelerator pedal or a second mode for releasing the AVH function by an increase of torque of the power train by depressing the brake pedal again is selected according to driving conditions.