Electric Motor Braking Torque for Faster Autonomous Emergency Stops
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Solution Overview
Problem
Current braking systems in autonomous vehicles take longer to build up brake pressure without driver input, leading to extended stopping distances during emergency braking, as they rely solely on the service brake system which is slower than a driver's manual operation.
Innovation Solution
A method where the longitudinal dynamics system, comprising an electric motor and a separate service brake system, automatically generates a total braking torque during emergency braking, with the electric motor providing initial braking torque quickly and the service brake system contributing once it can, ensuring rapid deceleration without driver intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the service brake system is used alone for emergency braking in autonomous vehicles, then the braking system is simpler, but the stopping distance increases due to slower brake pressure buildup
Solution Approach 1:
The patent combines the electric motor of the electric drive with the service brake system to create a hybrid braking system. The electric motor provides rapid initial braking torque while the service brake system builds up pressure, merging the advantages of both systems to achieve short stopping distances without requiring complex additional braking components
Solution Approach 2:
The electric motor serves dual functions: propulsion during normal operation and emergency braking assistance when needed. This multi-functionality allows the system to achieve rapid deceleration without adding dedicated braking components, maintaining system simplicity while improving stopping performance
2Loss of time
If the electric motor provides initial braking torque during emergency braking, then the stopping distance is reduced, but the control system becomes more complex
Solution Approach 1:
The control system automatically manages the coordination between the electric motor and service brake system without requiring manual driver input. The system self-regulates the braking torque distribution based on real-time conditions, performing the control function autonomously to reduce stopping distance while maintaining manageable control complexity
3Ease of operation
If autonomous vehicles operate without driver input for braking, then the ease of operation is improved, but the braking response time increases compared to manual driver operation
Solution Approach 1:
The electric motor is immediately activated to provide braking torque as soon as emergency braking is initiated, before the service brake system has time to build up pressure. This preliminary action compensates for the delay inherent in hydraulic brake pressure buildup, achieving rapid deceleration comparable to manual driver response while maintaining autonomous operation
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 allows for immediate and effective emergency braking in autonomous vehicles, reducing stopping distances by leveraging the electric motor's rapid torque changes to supplement the service brake system, thereby enhancing safety and reducing the need for manual driver input.
Implementation Method 1
an electric motor of an electric drive of the motor vehicle, which generates a first braking torque during the emergency braking maneuver
Implementation Method 2
a separate service brake system. For emergency braking, a total braking torque is automatically built up or generated by the longitudinal dynamics system of the motor vehicle
Data Source
Figure 1~2
AI summary
The invention relates to a method for decelerating a motor vehicle (1) during emergency braking, wherein the entire emergency braking operation is carried out automatically by a longitudinal dynamics system (5) of the motor vehicle (1), wherein in order to perform emergency braking an overall braking torque is generated automatically by the longitudinal dynamics system (5) of the motor vehicle (1), and for this purpose an electric motor (4) of an electric drive (3) of the motor vehicle (1) can generate a first braking torque at least as a portion of the overall braking torque, in a time interval (t0 to t32) starting with the automatic initiation of the emergency braking and for less than the overall time period of the emergency braking in which the overall braking torque can not yet be generated solely by a service brake system (6) of the longitudinal dynamics system. The invention further relates to a motor vehicle (1).