Towards Safer Autonomous Driving in an Open World: A Dual-Process Approach
Authors: Simon Janssen, Michiel Braat, Chris van der Ploeg, Serge Thill, Jan-Pieter Paardekooper
Organizations: Netherlands Organisation for Applied Scientific Research, Integrated Vehicle Safety Group, 5700 AT Helmond, The Netherlands · Eindhoven University of Technology, Dynamics and Control Group, Mechanical Engineering Dept., P.O. Box 513, 5600 MB, Eindhoven, The Netherlands · Radboud University, Donders Institute for Brain, Cognition and Behaviour, P.O.Box 9010, 6500 GL, Nijmegen, The Netherlands
Before autonomous driving systems can be deployed on public roads, it is vital that these systems comply with safety standards, traffic rules, and social norms. Although neural networks trained on large amounts of driving data perform well in routine driving tasks, these models often struggle in novel situations that are not well-represented in the data. In this work, we propose a novel framework that combines a neural network for intuitive, learning-based planning in routine driving tasks with model predictive control for reasoning-based planning in unfamiliar situations, inspired by Dual Process Theory. A meta-cognitive component is designed to switch between the two, using a knowledge graph to reason about contextual risk based on explicit perceptual information and relevant traffic rules and social norms. Contextual risk is represented through risk fields, guiding both the switching mechanism in the meta-cognitive component and compliance with safety standards, traffic rules, and social norms in the reasoning-based planner. The effectiveness of our framework is tested in CARLA for variations of a typical out-of-distribution situations involving (emergency) vehicles running a red light. We show that the novel architecture reduces the number of collisions in the scenarios by 89% and improves compliance with the special right-of-way rules, compared to the NN-only planner.
Figures & tables
Fig. 1 : The overall structure of the proposed framework.
Fig. 2 : Entity hierarchy.
Fig. 3 : Most important relations for physical entities.
Fig. 4 : Most important relations for infrastructure entities.
Priority
Natural Language Rule
0
When a line is dashed, it is acceptable to cross
0
When a line is solid, it is not acceptable to cross
0
When a line is a road edge, it is not acceptable to cross
1
When a line is dashed, it is on the left side of the road and connected to a lane in the opposite direction, it is not acceptable to cross
2
When a line is a left or right border of a lane that is itself part of an intersection, it is acceptable to cross
3
When a line is a left or right border of a lane that is itself part of an intersection, and the ego vehicle is on that lane, it is not acceptable to cross
TABLE I : Natural language descriptions and priorities of rules that specify line crossing acceptability.
Priority
Natural Language Rule
0
An object has medium risk.
1
When an object is behind the ego vehicle, it has low risk
2
When an object is in front of the ego vehicle,and the object is not on a lane in the opposite direction or a lane that is in the opposite direction of another lane that the ego vehicle can reach by following its current lane, and the ego vehicle could reach the object in less than 2 seconds (assuming constant ego velocity), it has high risk.
3
When an object has an object type emergency vehicle, it has high risk.
TABLE II : Natural language descriptions and priorities of rules that specify object risk levels.
Priority
Natural Language Rule
0
It is permissible to drive on a lane.
1
When a lane is in the opposite direction of the lane that the ego vehicle is currently on, or a lane is in the opposite direction of another lane that the ego vehicle can reach by following its current lane, it is not permissible to drive on.
TABLE III : Natural language descriptions and priorities of rules that specify driving permissibility.
Priority
Natural Language Rule
0
The ego vehicle has the right of way at an intersection.
1
When an intersection is managed by traffic lights, the traffic light is turned red, and this is the first intersection that the ego vehicle approaches by following its current lane, the ego vehicle does not have the right of way.
1
When an intersection is not managed by traffic lights, it is the first intersection that the ego vehicle approaches by following its current lane, it is the first intersection that another physical entity approaches by following its current lane, the physical entity comes from the right, and either the physical entity is expected to enter the intersection within 5 seconds, or its distance to the intersection is less than 10 meters, the ego vehicle does not have right of way.
2
When an intersection is the first intersection that the ego vehicle approaches by following its current lane, and it is the first intersection that another physical entity approaches, the physical entity has object type emergency vehicle, and either the physical entity is expected to enter the intersection within 10 seconds, or the distance to the intersection is less than 20 meters, the ego vehicle does not have right of way.
3
When the ego vehicle is on a lane that is part of an intersection, the ego vehicle has right of way.
TABLE IV : Natural language descriptions and priorities of right of way rules.
Object Class
Risk Level
AO
σx
σy
Car
Low
2
1.5lO+0.05
1.1wO+0.05
Car
Medium
3
1.5lO+0.1
1.1wO+0.1
Car
High
4
1.5lO+0.3
1.1wO+0.3
Pedestrian
Low
2
1.5lO+1.2
1.1wO+1.2
Pedestrian
Medium
4
1.5lO+1.7
1.1wO+1.7
Pedestrian
High
7
1.5lO+2.2
1.1wO+2.2
TABLE V : Risk parameters for objects, based on classification, dimensions, and risk level.
Lane Type
Acceptability
AL
σ
Regular
Acceptable
1.5
0.6
Regular
Not acceptable
4
0.6
Intersection
Acceptable
0
0.6
Intersection
Not acceptable
0.65
0.6
TABLE VI : Risk parameters for lane markings based on the lane type and line crossing acceptability.
Precedence
AI
σ
Right of way
0
1.5
No right of way
4
1.5
TABLE VII : Risk parameters for intersections based on right of way.
Permissibility
AD
Permissible
0
Not permissible
3
TABLE VIII : Risk parameters for lanes based on driving permissibility.
Par.
Description
Value
Unit
ts
Sampling time
0.15
s
N
Maximum trajectory horizon
20
-
T
Decision threshold MCC
0.7
-
ℓu
Input weights
[0.001, 1]
-
m
Terminal weights
[0.1, 0.01, 0, 0, 0]
-
x,xˉ
Position x-coordinate
[ −∞,∞ ]
m
TABLE IX : Simulation parameters.
Fig. 5 : For different intersection setups were used in the simulations.
Parameter
range
Scenario trigger distance
[20, 23, 27, 30] (m)
Adversary speed
[35, 40, 45, 50, 55] (km/h)
Adversary vehicle model
[ambulance, car]
Intersection
[A, C, B, D]
TABLE X : Scenario parameters.
Infraction Type
TF++
TF++ & MCC
TFv6
Collisions with Vehicle
48
5
8
Collisions with Road Layout
0
7
0
Outside lane
0
1
0
TABLE XI : Number of scenarios with infraction.
Fig. 6 : Collisions with vehicle per scenario parameter.
Fig. 7 : Snapshot where the MCC risk is above the threshold and the MPC is activated, stopping the vehicle.
Fig. 8 : Snapshot where the MCC risk is above the threshold and the MPC is activated adjusting the system I trajectory.
Fig. 9 : Snapshot where the MPC engages but only is able to calculate a path that collides with a roadside fence.
Autonomous driving develops vehicles that perceive road scenes, predict interactions, and plan and control safe movement with limited or no human input.
Department of Information Management, Peking University, Beijing 100871, China · School of Intelligence Science and Technology, Peking University, Beijing 100871, China · State Key Laboratory of General Artificial Intelligence, BIGAI, Beijing 100080, China +3