Heavy-Duty Vehicle Braking Control Under High Lateral Force
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Solution Overview
Problem
Heavy-duty vehicles with electrified propulsion systems face safety challenges during regenerative braking, particularly when the operator fails to react quickly to situations requiring foundation brakes due to insufficient brake torque from releasing the accelerator pedal, especially under conditions of high lateral forces.
Innovation Solution
A method and system that determine the maximum allowable lateral force on vehicle wheels based on vertical wheel force, road friction, and road inclination, transmitting a signal to the operator or automatically engaging foundation brakes when the lateral force exceeds this limit, ensuring safe braking by integrating electric machine and foundation brake systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If regenerative braking is used to extend battery operating distance, then energy efficiency is improved, but braking reliability deteriorates when lateral forces are high
Solution Approach 1:
The system dynamically adjusts the braking strategy based on real-time lateral force conditions. When lateral forces exceed the maximum allowable threshold, the control system automatically transitions from relying solely on regenerative braking to engaging foundation brakes, ensuring braking reliability is maintained under varying road conditions while preserving energy efficiency during normal operation
Solution Approach 2:
The system continuously monitors lateral forces on the wheels and provides feedback to the control unit. When the lateral force exceeds the calculated maximum allowable lateral force, the system receives feedback signaling insufficient brake torque and automatically engages foundation brakes, creating a closed-loop control system that ensures both energy efficiency and braking reliability
2Productivity
If one pedal speed control is implemented to increase regenerative braking occasions, then productivity is improved, but safety deteriorates due to delayed operator reaction
Solution Approach 1:
The system performs self-monitoring and self-correction by automatically detecting when lateral forces indicate insufficient brake torque and autonomously engaging foundation brakes without requiring operator intervention. This eliminates the safety gap caused by delayed human reaction while maintaining the productivity benefits of one-pedal speed control
Solution Approach 2:
The system proactively monitors lateral force conditions and prepares to engage foundation brakes before a safety-critical situation develops. By continuously comparing actual lateral forces against maximum allowable thresholds, the system takes preliminary action to prevent braking deficiencies rather than reacting after the operator detects a problem
3Reliability
If foundation brakes are engaged to ensure adequate braking force, then braking reliability is improved, but energy efficiency deteriorates due to loss of regenerative braking
Solution Approach 1:
The system dynamically selects the optimal braking mode based on real-time lateral force conditions. Foundation brakes are engaged only when lateral forces exceed the maximum allowable threshold, while regenerative braking remains the primary braking method during normal conditions, thus maintaining energy efficiency while ensuring braking reliability when needed
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
Enhances safety by providing timely alerts or automatic engagement of foundation brakes, ensuring adequate braking force is applied even when electric machines alone cannot reduce vehicle speed effectively, particularly in curved or inclined road conditions.
Implementation Method 1
the electric machines are configured to generate electric power during braking. In this situation, electric power generated by the electric machine is fed to the battery to charge the battery, so-called regenerative braking
Implementation Method 2
an estimated road friction between a tire surface of the at least one wheel and a road surface operable by the vehicle
Data Source
AI summary
A method of controlling a heavy-duty vehicle, comprising an electric machine configured to apply a propulsion torque on at least one wheel of the vehicle upon applying a pressure on an accelerator pedal of the vehicle, and to apply a brake torque on the at least one wheel upon releasing the pressure from the accelerator pedal, the method comprising determining a lateral force on the at least one wheel of the vehicle; determining a maximum allowable lateral force of the at least one wheel for obtaining a desired longitudinal brake force by the electric machine when releasing the pressure from the accelerator pedal; and transmitting a signal indicative of a foundation braking interaction to an operator of the vehicle when the lateral force is higher than the maximum allowable lateral force.