Latency-aware edge server for safe autonomous driving
Time: Wed 2021-07-14 10.00 - 10.30
Respondent: Mustafa Adnan , Reglerteknik - DCS
Opponent: Mustafa Al-Janabi
Supervisor: Frank Jiang
Examiner: Jonas Mårtensson
This thesis examines how a smart edge server, that communicates with autonomous vehicles in an intersection, could contribute to the safety of autonomous driving. Safe path planning is possible when an autonomous vehicle is aware of its surroundings such as obstacles, pedestrians and other vehicles. Occlusions in intersections caused by for instance buildings, trees and parked vehicles affect the sensing of autonomous vehicles which in turn lead to unsafe autonomous driving. Having a smart edge server that senses and processes useful information in the intersection such as pedestrians, obstacles and other vehicles and share it with autonomous vehicles will be beneficial for safe autonomous driving. However an important aspect that affects the safety is the delay caused by processing the information as well as the network latency. The path planning of an autonomous vehicle will not be accurate nor safe if the information of its surroundings is delayed and old.
The objective of this thesis is to implement a latency aware edge server that communicates with the autonomous vehicles and provide them information of their surroundings. For safe autonomous driving an obstacle avoidance Nonlinear Model Predictive Control, NMPC, algorithm is implemented using the information from the edge server. In order to avoid collisions in an intersection the edge server uses reachability analysis to compute the set of future possible states for each autonomous vehicle as zonotopes. These reachable sets along with static obstacles in the intersection are broadcasted as useful information. Each autonomous vehicle in the intersection listens to the edge server and adds those obstacles and other vehicles' reachable sets as unsafe sets in its obstacle avoidance NMPC formulation to plan a safe trajectory.
The implementations are evaluated for different scenarios and it is shown that a latency aware edge server reinforces safety for autonomous driving. The result shows that autonomous vehicles, that have intersecting paths, enter into unsafe situations if a smart edge server is not considered. When implementing the smart edge server with the obstacle avoidance NMPC the vehicles still enter into unsafe situations if the edge server does not take the delay into account in the reachable sets computation. Including latency awareness in the sense that the edge server takes the network latency and computational time into account the autonomous vehicles were able to avoid collision and plan a safe trajectory for different scenarios.