Autonomous Vehicle Brake Torque Control via Leading Vehicle Deceleration
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Solution Overview
Problem
In autonomous driving scenarios, existing technologies lack effective methods for safe emergency braking when the primary brake control system fails, particularly due to the absence of reliable sensor data for friction coefficient and wheel speed, which increases the risk of wheel locking and instability.
Innovation Solution
A method that utilizes an environment sensor system to determine the longitudinal deceleration of the vehicle ahead, allowing the secondary brake control system to build up braking torque at a controlled rate, ensuring safe deceleration without wheel locking, and includes a mechanism to estimate the minimum deceleration limit based on the vehicle ahead's dynamics and road friction, enabling driver-independent interventions for emergency braking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the secondary brake control system builds up braking torque rapidly to achieve fast deceleration, then the deceleration performance is improved, but the risk of wheel locking increases due to lack of friction coefficient data
Solution Approach 1:
The system performs preliminary assessment of the vehicle ahead's deceleration behavior before applying brake torque. By analyzing the longitudinal dynamics of the leading vehicle first, the system determines a safe deceleration limit value that prevents wheel locking while enabling rapid but controlled braking intervention.
Solution Approach 2:
The system uses feedback from the environment sensor system regarding the vehicle ahead's deceleration to continuously adjust the braking torque application. The brake control system monitors the deceleration limit value derived from the leading vehicle's behavior and adjusts the braking torque build-up rate accordingly, switching between first and second build-up rates based on real-time conditions.
2Ease of manufacture
If the brake control system uses a single-channel design for cost reduction, then the manufacturing cost is reduced, but the system complexity for reliable emergency braking is reduced
Solution Approach 1:
The single-channel brake control system is designed to perform multiple functions: normal braking, emergency braking, and wheel locking prevention. By making the system universal and capable of handling all braking scenarios through intelligent control algorithms rather than dedicated hardware channels, the system achieves cost reduction while maintaining reliability.
Solution Approach 2:
The system compensates for the simplified single-channel design by dynamically changing control parameters such as brake torque build-up rate and deceleration limit values. These parameter adjustments enable the system to adapt to different emergency situations and maintain reliable emergency braking performance despite the reduced hardware complexity.
3Reliability
If the system determines deceleration limit based on vehicle ahead's dynamics, then the braking safety is improved, but the response time is increased due to additional analysis
Solution Approach 1:
The system continuously monitors and analyzes the longitudinal dynamics of the vehicle ahead in advance, maintaining ready-to-use deceleration limit values. This preliminary analysis ensures that when emergency braking is required, the system can immediately apply pre-determined safe deceleration limits without delayed calculation, thus improving both safety and response time.
Data Source
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AI summary
The invention relates to a method for longitudinal dynamic regulation in a motor vehicle during an autonomous driving operation, wherein, by means of an environment sensor system, the presence of a vehicle travelling in front of the motor vehicle is determined, by means of the environment sensor system, at least one front vehicle longitudinal dynamic value is determined which describes the longitudinal dynamic of the vehicle in front, and, depending upon the front vehicle longitudinal dynamic value, at least one value is determined which is entered into a brake regulation system of the motor vehicle.