Adaptive Cruise Control for Abrupt Target Vehicle Deceleration
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Solution Overview
Problem
Existing adaptive cruise control systems in autonomous vehicles fail to maintain a safe inter-vehicle distance when target vehicles decelerate abruptly, leading to psychological discomfort and potential emergency braking due to delays in data processing and actuator response.
Innovation Solution
An adaptive cruise control method that substitutes the target vehicle's acceleration as the setpoint when the calculated inter-vehicle time falls below a predetermined percentage and the target acceleration is less than a threshold, ensuring smoother vehicle approach and reducing the need for emergency braking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the adaptive cruise control uses a predetermined inter-vehicle time setpoint to calculate acceleration setpoint, then the speed regulation is stable, but the responsiveness to target vehicle deceleration is delayed
Solution Approach 1:
The system dynamically adjusts the acceleration setpoint based on real-time conditions. When the target vehicle decelerates strongly, the system transitions from using a predetermined inter-vehicle time setpoint to directly using the target vehicle's deceleration as the acceleration setpoint, making the speed regulation adaptive and responsive to changing conditions
Solution Approach 2:
The system continuously monitors the inter-vehicle time and compares it with the predetermined setpoint. When the calculated inter-vehicle time falls below a threshold (indicating the target vehicle is decelerating), the system receives feedback and adjusts the acceleration setpoint accordingly, creating a closed-loop control that improves responsiveness
2Ease of operation
If the adaptive cruise control calculates acceleration setpoint with predetermined inter-vehicle time, then the control is smooth, but the inter-vehicle distance is not maintained when target vehicle decelerates abruptly
Solution Approach 1:
The system changes the control parameter from a fixed predetermined inter-vehicle time setpoint to a variable acceleration setpoint that directly reflects the target vehicle's deceleration. This parameter change allows the system to maintain the inter-vehicle distance accurately even when the target vehicle decelerates abruptly
3Device complexity
If the system uses calculation times and actuator response times (around 500 ms), then the processing is manageable, but the autonomous vehicle approaches the target vehicle too abruptly at low speeds
Solution Approach 1:
The system performs preliminary monitoring of the inter-vehicle time and detects when it falls below the threshold before the actual deceleration becomes problematic. This allows the system to prepare and apply the corrected acceleration setpoint in advance, compensating for the inherent 500 ms delay in calculation and actuator response
Solution Approach 2:
The system applies a cushioning effect by using the target vehicle's deceleration directly as the acceleration setpoint, which creates a smoother deceleration profile that anticipates the need for gradual speed reduction, thereby reducing abrupt approaches and psychological discomfort
Data Source
AI summary
The invention relates to a method and a device for regulating the speed of an autonomous vehicle, referred to as ego vehicle, comprising an adaptive cruise control, said method comprising the steps of activating (201) said adaptive cruise control, receiving (202) information relating to said target vehicle, referred to as target information, receiving (203) information relating to said ego vehicle, referred to as ego vehicle information, determining (204) an inter-vehicle time, determining (205) an alert signal from said target information and said ego vehicle information, determining conditions (206) for substituting (207) a target acceleration for a setpoint acceleration of said cruise control.