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With the recent advances in intelligent vehicular ad-hoc networks (inVANETs), the traditional traffic control problem at intersections is being revisited to cope with the future intelligent transportation systems. The traditional traffic light scheduling, the recently developed artificial-intelligence-based traffic control approaches, or the trajectory maneuver remain all either inaccurate, inflexible,...
With increasing numbers of air traffic, and new kinds of air traffic emerging, new strategies are being developed in air traffic management to guarantee the safety of air traffic. Decision support tools in operation today barely extend beyond safety net features providing last-minute alerts for evasive actions. Tools with a greater time horizon to facilitate timely and gentle corrective action are...
We explore the probabilistic foundations of shared control in complex dynamic environments. In order to do this, we formulate shared control as a random process and describe the joint distribution that governs its behavior. For tractability, we model the relationships between the operator, autonomy, and crowd as an undirected graphical model. Further, we introduce an interaction function between the...
This paper addresses the air traffic control problem of conflict detection and resolution (CDR) under intent uncertainty, in a multiple model (MM) trajectory information processing framework. The conflict detection is based on a predicted probability of conflict. The problem of conflict resolution (CR) is formulated as one of a chance-constrained model predictive control, whereby the constraint is...
The improvement of collision avoidance for vessels in close range encounter situations is an important topic for maritime traffic safety. Typical approaches generate evasive trajectories or optimise the trajectories of all involved vessels. The idea of this work is to validate these trajectories related to guaranteed motion safety, which means that it is not sufficient for a trajectory to be collision-free,...
To be safe, mobile multi-robots systems need to be able to adapt to unexpected behaviours of robots as well as to exogenous changes in the environment. In this paper, we describe a novel approach for the development of multi-robots systems where robots collectively collaborate with each other to satisfy their goals and to adapt their behaviour in a collective way satisfying the overall system safety...
We address the problem of verifying motion plans for aerial robots in uncertain and partially-known environments. Thereby, the initial state of the robot is uncertain due to errors from the state estimation and the motion is uncertain due to wind disturbances and control errors caused by sensor noise. Since the environment is perceived at runtime, the verification of partial motion plans must be performed...
In this paper, we present a new robotic uterine positioner for total laparoscopic hysterectomy. The robot is designed to actively position the patient's uterus during surgery, a lengthy and tedious task that is traditionally performed by a human assistant. Safety is simply the most important concern when developing robots for surgical purposes; we address this concern in the design of our robot from...
This paper presents recent findings in maritime trajectory pattern and anomaly detection using long-term data collected via a shore-based network of Automatic Identification System (AIS). Since the establishment of the AIS network around Taiwan in 2009, the accumulated massive vessel trajectories have been extensively explored under a series of government research projects. The project themes include...
Hamilton-Jacobi-Isaacs (HJI) reachability analysis has been employed to guarantee safety in a number of applications including robotics, air traffic control, and control of HVAC systems. The current standard for these methods can result in overly-conservative controllers that degrade system performance with respect to other objectives. There has been interest in incorporating online machine learning...
This paper is concerned with the development of motion safety criteria and associated proofs of safe operation for the class of reciprocal collision avoidance methods based on the relative velocity paradigm; including Velocity Obstacles (VO), Reciprocal Velocity Obstacles (ORCA), and Continuous Control Obstacles (CCO) - thus covering both holonomic and non-holonomic configurations. In the first part...
In this paper, a model predictive control approach is proposed for a vehicle convoy traveling on homogeneous highway. Specifically, the lane change behavior of a cut-in vehicle in front of the vehicle convoy is estimated and predicted for the predictive control of the leading vehicle in the convoy. In order to capture state differences of the preceding vehicle in different lane change manners, a cost...
This paper presents a new controller for prevention of unintended roadway departures using model predictive control (MPC). The uncertainty with the driver's behavior is taken into account as the Gaussian disturbance. Correspondingly, we impose a lower bound on the probability of the vehicle remaining within the lane. Using current information of the vehicle and predicted steering of the driver, a...
This paper considers the trajectory planning problem of a vehicle system for automated lane change maneuvers. By considering a lane change maneuver as primarily a longitudinal planning problem, the proposed trajectory planning algorithm determines whether there exists a longitudinal trajectory which allows the ego vehicle to safely position itself in a gap between surrounding vehicles in the target...
Geometric controllers for mechanical system have been well-developed in past research work. Although geometric controllers possess the advantages of being coordinate-free and compact, these controllers don't take into account constraints such as safety-critical collision constraints or input saturations. In this paper, we utilize the concepts of control Lyapunov function(CLF) and control Barrier function(CBF)...
In this paper, we have considered the development of predictive collision avoidance as an individual driver behavior modeling. First, our investigation focuses on developing a subjective collision risk estimation model. Through the game theoretic estimation of the counterpart's behaviors and the corresponding time-evolution of the unsafe collision areas, we compute an objective collision model. In...
We consider the problem of coordinating a set of automated vehicles at an intersection with no traffic light. The priority-based coordination framework is adopted to separate the problem into a priority assignment problem and a vehicle control problem under fixed priorities. This framework ensures good properties like safety (collision-free trajectories, brake-safe control) and liveness (no gridlock)...
For a closed-loop system composed of a linear controlled plant and an MPC feedback strategy we show how to verify that closed-loop state trajectories either enter or avoid a given set of unsafe states. The search for the safety certificate is formulated as a mixed-integer linear programming problem which yields non-conservative certificates. The optimal control commands generated by the MPC policy...
This paper addresses some alternatives to classical trajectory generation for an autonomous vehicle which needs to pass through a priori given way-points. Using differential flatness for trajectory generation and B-splines for the flat output parametrization, the current study concentrates on constraint relaxations and on obstacle avoidance conditions. The results are validated through simulations...
This paper describes the development of a Sense and Avoid (S&A) algorithm that can ensure an Unmanned Aerial Vehicle (UAV) being able to avoid collisions autonomously. Firstly, the Closest Point of Approach (CPA) can predict the conflict. Secondly, the developed path planner generates the feasible path using differential geometric guidance and flatness techniques, where the constraints of UAV...
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