Brake Booster Validation Signal for Driver Override Detection
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Solution Overview
Problem
Existing brake systems face challenges in reliably detecting driver manipulation of the brake pedal during autonomous emergency braking, particularly in small differential travel ranges, due to mechanical tolerances and the need for plausibility checks.
Innovation Solution
A method that superimposes a varying validation signal on the control of the autonomous driving system to monitor the differential travel between the actuator element and the brake pedal, allowing detection of driver manipulation by analyzing changes in differential travel, ensuring the validation signal is unique and not replicable by pedal manipulation, thereby enhancing the reliability of emergency braking activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the brake pedal manipulation is detected by monitoring differential travel between the brake pedal and actuator element, then the emergency braking can be initiated, but the detection reliability deteriorates in small differential travel ranges due to mechanical tolerances
Solution Approach 1:
A validation signal is introduced as an intermediary element between the autonomous driving system control and the brake actuator. This validation signal modulates the actuator's movement in a detectable pattern, allowing the system to distinguish between actuator movements caused by autonomous control and those caused by actual brake pedal manipulation by the driver, thereby resolving the detection reliability issue in small differential travel ranges
Solution Approach 2:
The system continuously monitors the differential travel between the brake pedal and actuator element and compares it against expected values based on the validation signal. This feedback mechanism allows real-time detection of deviations indicating driver intervention, maintaining reliable detection even when mechanical tolerances cause small variations in the differential travel
2Reliability
If the mechanical catch limits the differential travel to prevent unnecessary emergency braking, then false emergency braking is reduced, but the ability to detect driver manipulation deteriorates in small differential travel ranges
Solution Approach 1:
The validation signal dynamically modulates the actuator's position within the mechanically limited differential travel range. By creating a time-varying pattern of differential travel that is superimposed on the static mechanical catch limitation, the system enables detection of driver manipulation through changes in the validation signal pattern, resolving the detection difficulty caused by the mechanical catch
3Extent of automation
If the brake booster pulls along the brake pedal during autonomous braking, then emergency braking can be executed without driver input, but the detection of driver manipulation becomes more complex
Solution Approach 1:
The validation signal serves as an intermediary that decouples the complexity of detecting driver manipulation from the autonomous braking control. By modulating the actuator through this validation signal, the system creates a clear reference pattern against which driver input can be detected, simplifying the overall detection logic despite the brake booster's ability to move the pedal autonomously
Data Source
AI summary
A method for operating a brake system of a vehicle, in particular, of a motor vehicle. The brake system includes at least one electric actuator, in particular, a brake booster, which may be driven to generate a braking force, the actuator being controllable by an autonomous driving system, and as a function of manipulation of a brake pedal of the vehicle; and an emergency braking action being initiated, when the actuator is driven both by the autonomous driving system and by manipulation of a brake pedal. The control by the autonomous driving system is superimposed with a varying validation signal, a differential travel between an actuator element of the actuator and the brake pedal is monitored, and the driving of the actuator via manipulation of the brake pedal during the control by the autonomous driving system is detected, if the differential travel varies.