Autonomous Vehicle Brake Control for Smooth Hill Drive-Off

Solution Overview

Problem

Autonomous driving vehicles face challenges in controlling braking on gradients, leading to rolling issues and inefficient acceleration from a stop, which affects safety, passenger comfort, and efficiency, especially on inclined surfaces.

Innovation Solution

A redundant holding control system that dynamically activates primary, secondary, and electronic parking brakes, and engine brake based on rolling speed and distance from obstacles, combined with adaptive torque control for smooth acceleration, to prevent rolling and ensure safe and agile drive-off on various slopes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the ADV applies brake torque quickly to prevent rolling, then vehicle stability is improved, but passenger comfort deteriorates due to high ramp-up rates

Engineering Contradiction:

Improvevehicle stabilityVSAvoidpassenger comfort

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies dynamics by making the brake torque ramp-up rate adaptive rather than fixed. The control system dynamically adjusts the ramp-up rate based on real-time vehicle status (including slope, speed, and braking force), allowing the system to optimize between stability and comfort for each specific situation. This resolves the contradiction by enabling the system to apply sufficient braking force while controlling the rate of application to remain comfortable for passengers.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the parameter of brake torque ramp-up rate from a constant value to a variable parameter that adjusts based on vehicle conditions. By modifying this parameter dynamically according to slope, speed, and braking force, the system can achieve both high vehicle stability (through adequate braking) and passenger comfort (through controlled rate of application).

Inventive Principle:

Principle #35Parameter changes

2Productivity

If the ADV accelerates quickly from a stop, then productivity is improved, but safety deteriorates due to potential rollback on gradients

Engineering Contradiction:

Improvedrive-off speedVSAvoidvehicle stability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies preliminary action by having the braking system engage before the drive-off maneuver begins. The system determines the appropriate braking force based on slope and other factors, applies this braking force prior to acceleration, and then releases it in a controlled manner during the drive-off. This preliminary braking action prevents rollback while enabling smooth and efficient acceleration, resolving the contradiction between productivity and safety.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent ensures continuity of useful action by maintaining braking force throughout the drive-off process rather than applying it intermittently. The braking force is applied continuously and adjusted dynamically based on real-time vehicle status, ensuring stable prevention of rollback while enabling continuous smooth acceleration. This continuous control resolves the contradiction by maintaining both safety and productivity throughout the entire drive-off maneuver.

Inventive Principle:

Principle #20Continuity of useful action

3Reliability

If the ADV uses a high ramp-up rate of brake torque, then vehicle stability is improved, but passenger comfort deteriorates

Engineering Contradiction:

Improvevehicle stabilityVSAvoidpassenger comfort

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent applies dynamics by making the brake torque ramp-up rate adaptive rather than fixed. The control system dynamically adjusts the ramp-up rate based on real-time vehicle status (including slope, speed, and braking force), allowing the system to optimize between stability and comfort for each specific situation. This resolves the contradiction by enabling the system to apply sufficient braking force while controlling the rate of application to remain comfortable for passengers.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the parameter of brake torque ramp-up rate from a constant value to a variable parameter that adjusts based on vehicle conditions. By modifying this parameter dynamically according to slope, speed, and braking force, the system can achieve both high vehicle stability (through adequate braking) and passenger comfort (through controlled rate of application).

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS20250018947A1Vehicle control for autonomous driving vehicle for smooth drive-off

Publication Date: 2025.01.16 APOLLO AUTONOMOUS DRIVING USA LLC

AI summary

Smooth and agile acceleration of an autonomous driving vehicle (ADV) that is being held at a standstill or is otherwise at a stop is important for ADV safety, efficiency, and occupant enjoyment. For example, as a practical matter, an ADV at an uncontrolled intersection should quickly and smoothly drive-off when it is its turn to advance—otherwise, it may get stuck at the intersection. Embodiments herein provide systems and methods to facilitate a pleasant and comfortable ride while having the ADV drive off smoothly (e.g., not a large jerk) and safely while driving from a stop—regardless of whether the ADV is on a sloped surface.