Occlusion-Aware CACC Safety Speed Control
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Solution Overview
Problem
Existing vehicular platooning systems face challenges in maintaining safety during environmental occlusions and cyber-attacks, as erroneous relative spacing measurements can lead to collisions and destabilization of the vehicle string.
Innovation Solution
A new occlusion-aware cooperative adaptive cruise control (CACC) strategy that determines a safety speed based on minimum spacing and relative velocity values before occlusion, and adjusts the control command to maintain a speed that ensures collision-free operation even during occlusions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If memory-hold method is used to manage environmental interference, then short occlusions can be handled, but safety cannot be guaranteed for relatively longer occlusions
Solution Approach 1:
The system performs preliminary actions by determining minimum spacing and velocity values, and calculating a safety speed threshold before the occlusion occurs. This allows the system to have safety parameters ready in advance, enabling it to maintain safety even during extended occlusion periods when sensor data is unavailable.
Solution Approach 2:
The system applies beforehand cushioning by using the determined safety speed as a protective threshold that prevents collisions during occlusion. By maintaining speed below this pre-calculated threshold, the system creates a safety buffer that compensates for the lack of real-time sensor information during long occlusions.
2Reliability
If filtering techniques are used to estimate lost communication signals, then collision prevention is possible when CACC degrades to ACC, but the technique requires accurate onboard sensor measurements which may not be available during jamming
Solution Approach 1:
The system uses an intermediary approach by relying on pre-determined safety parameters (minimum spacing, minimum velocity, and safety speed) that were calculated before occlusion. These intermediary values serve as substitutes for real-time sensor measurements, allowing the system to prevent collisions even when both communication and sensor measurements are unavailable due to jamming.
3Ease of operation
If ACC uses relative spacing and velocity measurements to determine control actions, then cruise control functionality is achieved, but erroneous measurements from environmental occlusions or cyber-attacks can cause collisions or destabilize the vehicle string
Solution Approach 1:
The system applies preliminary anti-action by determining safety constraints (minimum spacing, minimum velocity, and safety speed) before environmental interference occurs. These pre-established constraints act as protective measures that prevent erroneous control actions during occlusions or cyber-attacks, thereby counteracting the harmful effects before they can cause collisions or destabilization.
Data Source
AI summary
In some embodiments, a method of controlling speed of an ego vehicle in a vehicle platoon is provided. Cooperative adaptive cruise control (CACC) commands based on at least one of a vehicle-to-vehicle communication control received from a preceding vehicle and a feedback control based on a sensor output of a long-range sensor of the ego vehicle are provided to a speed controller. In response to detecting an occluded state, a minimum spacing value and a minimum relative velocity value between the ego vehicle and the preceding vehicle are determined based on information received before the detection of the occluded state; a safety speed based on the minimum spacing value and the minimum relative velocity value is determined; and an occluded adaptive cruise control command is provided to the speed controller to maintain a speed of the ego vehicle that is less than or equal to the safety speed.