Ride-hailed shared autonomous vehicles (SAV) have emerged recently as an economically feasible way of introducing autonomous driving technologies while serving the mobility needs of under-served ...communities. There has also been corresponding research work on optimization of the operation of these SAVs. However, the current state-of-the-art research in this area treats very simple networks, neglecting the effect of a realistic other traffic representation, and is not useful for planning deployments of SAV service. In contrast, this paper utilizes a recent autonomous shuttle deployment site in Columbus, Ohio, as a basis for mobility studies and the optimization of SAV fleet deployment. Furthermore, this paper creates an SAV dispatcher based on reinforcement learning (RL) to minimize passenger wait time and to maximize the number of passengers served. The created taxi-dispatcher is then simulated in a realistic scenario while avoiding generalization or over-fitting to the area. It is found that an RL-aided taxi dispatcher algorithm can greatly improve the performance of a deployment of SAVs by increasing the overall number of trips completed and passengers served while decreasing the wait time for passengers.
This paper presents a trajectory planning framework to deal with the highly dynamic environments for on-road driving. The trajectory optimization problem with parameterized curvature control was ...formulated to reach the goal state with the vehicle model and its dynamic constraints considered. This in contrast to existing curve fitting techniques guarantees the dynamic feasibility of the planned trajectory. With generation of multiple trajectory candidates along the Frenet frame, the vehicle is reactive to other road users or obstacles encountered. Additionally, to deal with more complex driving scenarios, its seamless interaction with an upper behavior planning layer was considered by having longitudinal motion planning responsive to the desired goal state. The trajectory evaluation and selection methodologies, along with the low-level tracking control, were also developed under this framework. The potential of the proposed trajectory planning framework was demonstrated under different dynamic driving scenarios such as lane-changing or merging with surrounding vehicles with its computation efficiency proven in real-time simulations.
In this paper, explicit model predictive control (MPC) of a two-stage turbocharged diesel engine is presented. MPC provides superior performance over conventional map-based PID boost pressure ...control. It can be easily adapted to multivariable control and is relatively easy to tune. A control-oriented multiple-input multiple-output model of a turbocharged diesel engine was derived using system identification methods. As MPC control design is based on a linear model, validation of the controller was carried out using a high-fidelity nonlinear engine model. Using the high-fidelity simulation model provides the opportunity to fine-tune the controller before the real-time testing. The experimental real-time tests demonstrate a superior control performance in a wider range compared with the performance obtained using conventional control.
Connectivity between ground vehicles can be utilized and expanded to include aerial vehicles for coordinated missions. Using Vehicle-to-Everything (V2X) communication technologies, a communication ...link can be established between Connected and Autonomous vehicles (CAVs) and Unmanned Aerial vehicles (UAVs). Hardware implementation and testing of a ground-to-air communication link are crucial for real-life applications. In this paper, the V2X communication and coordinated mission of a CAV & UAV are presented. Four methods were utilized to establish communication between the hardware and software components, namely Dedicated Short Range communication (DSRC), User Datagram Protocol (UDP), 4G internet-based WebSocket and Transmission Control Protocol (TCP). These communication links were used together for a real-life use case scenario called Quick Clear demonstration. In this scenario, the first aim was to send the accident location information from the CAV to the UAV through DSRC communication. On the UAV side, the wired connection between the DSRC modem and Raspberry Pi companion computer was established through UDP to get the accident location from CAV to the companion computer. Raspberry Pi first connected to a traffic contingency management system (CMP) through TCP to send CAV and UAV location, as well as the accident location, information to the CMP. Raspberry Pi also utilized WebSocket communication to connect to a web server to send photos that were taken by the camera that was mounted on the UAV. The Quick Clear demonstration scenario was tested for both a stationary test and dynamic flight cases. The latency results show satisfactory performance in the data transfer speed between test components with UDP having the least latency. The package drop percentage analysis shows that the DSRC communication showed the best performance among the four methods studied here. All in all, the outcome of this experimentation study shows that this communication structure can be utilized for real-life scenarios for successful implementation.
This paper is on a pedestrian collision avoidance system for low speed autonomous shuttles based on Vehicle-to-Pedestrian (V2P) communication. When pedestrians cannot be detected using line-of-sight ...sensors like camera, radar and LIDAR, V2P communication with the Dedicated Short Range Communication (DSRC) enabled pedestrian smartphone is used to detect and localize them through the in-vehicle DSRC radio used for Vehicle-to-Everything (V2X) communication. The vehicle, then, either stops or, if possible, goes around the pedestrian in a socially acceptable manner using the elastic band method for locally modifying the vehicle trajectory in real time. The elastic band method of collision avoidance is modified for fast real time execution in this paper. Along with model-in-the-loop simulations, a hardware-in-the-loop simulator using an automated driving vehicle model in the high fidelity vehicle dynamics simulation program Carsim Real Time with Sensors and Traffic with two DSRC modems emulating the vehicle and pedestrian communications is introduced and used in this paper as a prerequisite to real world experiments. Both stationary and moving pedestrians are considered in the model and hardware-in-the-loop simulations. Two real world experiments are also presented to demonstrate the V2P based avoidance of crashes between low speed autonomous shuttles and pedestrians.
An ABS control algorithm based on extremum seeking is presented in this brief. The optimum slip ratio between the tire patch and the road is searched online without having to estimate road friction ...conditions. This is achieved by adapting the extremum-seeking algorithm as a self-optimization routine that seeks the peak point of the tire force-slip curve. As an additional novelty, the proposed algorithm incorporates driver steering input into the optimization procedure to determine the operating region of the tires on the "tire force"-"slip ratio" characteristic-curve. The algorithm operates the tires near the peak point of the force-slip curve during straight line braking. When the driver demands lateral motion in addition to braking, the operating regions of the tires are modified automatically, for improving the lateral stability of the vehicle by increasing the tire lateral forces. A validated, full vehicle model is presented and used in a simulation study to demonstrate the effectiveness of the proposed approach. Simulation results show the benefits of the proposed ABS controller.
This paper is motivated by the autonomous shuttle service that operates in the geo-fenced Linden Residential Area of Columbus, Ohio that links residents to the two nearby locations of opportunity of ...a community center and a transit hub. This paper focuses on path planning and path tracking of an autonomous shuttle which are its most fundamental autonomous driving functions. Path planning is based on improving efficiency of computation and smoothness of path. Velocity planning is based on obeying speed limits, limiting longitudinal acceleration along straight segments and lateral acceleration during curved segments for improved ride comfort of the passengers. Path tracking control focuses on robust implementation that keeps accuracy of path following in the presence of uncertainties and variations in speed. A realistic, 3D virtual simulation environment of the actual geo-fenced urban area used here is built for evaluating and developing the path planning and path tracking functions of this paper. The same environment can also be used for developing and evaluating other autonomous driving functions with the capability of generating complicated traffic scenarios. The path tacking control results are compared with those of the pure pursuit path tracking algorithm of the open source and publicly available Autoware autonomous driving interface for the Robot Operating System.
This paper is on the design of cooperative adaptive cruise control systems for automated driving of platoons of vehicles in the longitudinal direction. Longitudinal models of vehicles with simple ...dynamics, an uncertain first order time constant and vehicle to vehicle communication with a communication delay are used in the vehicle modeling. A robust parameter space approach is developed and applied to the design of the cooperative adaptive cruise control system. D-stability is chosen as the robust performance goal and the feedback PD controller is designed in controller parameter space to achieve this D-stability goal for a range of possible longitudinal dynamics time constants and different values of time gap. Preceding vehicle acceleration is sent to the ego vehicle using vehicle to vehicle communication and a feedforward controller is used in this inter-vehicle loop to improve performance. Simulation results of an eight vehicle platoon of heterogeneous vehicles are presented and evaluated to demonstrate the efficiency of the proposed design method. Also, the proposed method is compared with a benchmark controller and the feedback only controller. Time gap regulation and string stability are used to assess performance and the effect of the vehicle to vehicle communication frequency on control system performance is also investigated.
The current approach to connected and autonomous driving function development and evaluation uses model-in-the-loop simulation, hardware-in-the-loop simulation and limited proving ground use, ...followed by public road deployment of the beta version of software and technology. The rest of the road users are involuntarily forced into taking part in the development and evaluation of these connected and autonomous driving functions in this approach. This is an unsafe, costly and inefficient method. Motivated by these shortcomings, this paper introduces the Vehicle-in-Virtual-Environment (VVE) method of safe, efficient and low-cost connected and autonomous driving function development, evaluation and demonstration. The VVE method is compared to the existing state-of-the-art. Its basic implementation for a path-following task is used to explain the method where the actual autonomous vehicle operates in a large empty area with its sensor feeds being replaced by realistic sensor feeds corresponding to its location and pose in the virtual environment. It is possible to easily change the development virtual environment and inject rare and difficult events which can be tested very safely. Vehicle-to-Pedestrian (V2P) communication-based pedestrian safety is chosen as the application use case for the VVE in this paper, and corresponding experimental results are presented and discussed. A no-line-of-sight pedestrian and vehicle moving towards each other on intersecting paths with different speeds are used in the experiments. Their time-to-collision risk zone values are compared for determining severity levels. The severity levels are used to slow down or brake the vehicle. The results show that V2P communication of pedestrian location and heading can be used successfully to avoid possible collisions. It is noted that actual pedestrians and other vulnerable road users can be used very safely in this approach.
A parameter‐space‐based robust platooning controller for the event‐triggered heterogeneous platoon is presented. The novel heterogeneous platoon is established with different longitudinal vehicle ...dynamic and driving preferences and the event‐triggered communication scheme is designed to reduce the utilization of communication resources. To handle the stricter demand of the heterogeneous system and the disturbance caused by event‐triggered communication scheme, the parameter space approach is adopted to optimize the gains of a robust controller. The feasible region where internal stability and L2 string stability are satisfied is then visualized in the parameters space, by extending the parameter space approach to the D‐stability and frequency response magnitude specifications. Subsequently, the robust controller, which combines the feedforward loop and feedback loop, is developed by selecting the gain from the feasible solution area. The simulation results of the event‐triggered heterogeneous platoon are presented and evaluated to verify the efficiency of this control algorithm. It is seen that the internal stability and string stability of the event‐triggered heterogeneous platoon are guaranteed by this robust controller. Furthermore, 89.7% of communication resources are saved by the application of event‐triggered communication scheme, while the following performance is also favourable during the highway fuel economy cycle.
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