Autonomous Vehicle Emergency Stop Trajectory Control
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Solution Overview
Problem
Current devices for determining an emergency stop trajectory for autonomous vehicles rely solely on the last movement vector, leading to violent and unsafe braking, especially in curved lanes, which can result in the vehicle leaving the road, and fail to maintain a non-zero speed in risky zones.
Innovation Solution
A device that determines the emergency stop trajectory by using both the last movement vector and predefined trajectory reference vectors, allowing real-time correction and optimization of the braking process to maintain the vehicle on the predefined path, ensuring a 'soft' deceleration and minimizing lateral offset.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If sudden automatic braking is applied to reduce speed to 20 km/h or less, then the emergency stop is achieved quickly, but the braking becomes violent and unsafe for passengers
Solution Approach 1:
The patent applies dynamics by making the deceleration profile adaptive rather than fixed. The control device dynamically adjusts the deceleration rate based on real-time vehicle state (position, speed, trajectory) and environmental conditions (road curvature, distance to obstacles). This allows the system to optimize the balance between stopping speed and passenger comfort/safety, transitioning from static sudden braking to dynamic controlled deceleration.
Solution Approach 2:
The patent changes the parameter of deceleration from a fixed value (sudden braking to 20 km/h) to a variable parameter that is continuously adjusted. The control device modifies deceleration parameters based on multiple factors including vehicle position on the trajectory, current speed, road geometry, and obstacle distance. This parameter change enables smooth, adaptive deceleration that maintains safety while achieving the emergency stop.
2Loss of time
If sudden automatic braking is applied, then the vehicle stops quickly, but the vehicle may leave the road due to lane curvature changes during stopping
Solution Approach 1:
The patent implements feedback by continuously monitoring the vehicle's actual position relative to the predefined emergency stop trajectory and using this information to adjust control commands. The control device receives real-time data on vehicle position, compares it with the reference trajectory, and modifies steering and braking commands to keep the vehicle on the intended path. This closed-loop feedback control prevents the vehicle from leaving the road during the stopping process.
Solution Approach 2:
The patent applies preliminary action by pre-calculating and storing an emergency stop trajectory that accounts for potential road curvature changes. Before the actual stopping begins, the system has already determined a safe stopping path that considers the road geometry. During execution, the vehicle follows this pre-planned trajectory, which was designed to maintain road contact even as speed decreases and lane curvature may change.
3Reliability
If the vehicle stops completely in risky zones (intersections, pedestrian areas), then safety is compromised, but maintaining non-zero speed increases stopping distance
Solution Approach 1:
The patent applies preliminary action by pre-identifying risky zones (intersections, pedestrian areas, other vehicles) along the emergency stop trajectory and planning the stopping sequence in advance. The control device determines which zones should be avoided and calculates a stopping strategy that brings the vehicle to a complete stop only in safe zones, while maintaining slow non-zero speed when passing through risky zones. This pre-planned approach balances safety requirements with the need to minimize stopping distance.
4Device complexity
If only the last movement vector is used to determine emergency stop trajectory, then the control system is simple, but the trajectory optimization is insufficient
Solution Approach 1:
The patent applies preliminary action by pre-storing the complete emergency stop trajectory (including reference vectors for position, speed, and acceleration at multiple future time steps) in the control device's memory before an emergency situation occurs. When emergency braking is triggered, the system retrieves and executes this pre-calculated optimal trajectory rather than computing it in real-time. This approach maintains relatively simple hardware while achieving high trajectory accuracy through advance planning and storage of optimized control parameters.
Data Source
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AI summary
This device (10) is automatically activated in the presence of an emergency stop instruction, and includes: - a calculation module (14) for at least one instruction for the automatic movement of the vehicle to follow an emergency stop trajectory comprising a plurality of successive emergency stop vectors (VE1, VE2, VE3) each associated with a segment (P2, P3, P4) distinct from a part of the successive segments of the predefined trajectory, based at least for each emergency stop vector (VE1, VE2, VE3): ∘ on a last actual movement vector of the autonomous vehicle (A) stored, ∘ on the predefined movement trajectory of the autonomous vehicle, and ∘ on a last location data of the autonomous vehicle (A) stored, and delivered by at least one sensor of the autonomous vehicle (A), - an emergency steering module (16) capable of directing the vehicle according to said at least one instruction.