Autonomous vehicles are expected to play a key role in the future of urban transportation systems, as they offer potential for additional safety, increased productivity, greater accessibility, better road efficiency, and positive impact on the environment. Research in autonomous systems has seen dramatic advances in recent years, due to the increases in available computing power and reduced cost in sensing and computing technologies, resulting in maturing technological readiness level of fully autonomous vehicles. The objective of this paper is to provide a general overview of the recent developments in the realm of autonomous vehicle software systems. Fundamental components of autonomous vehicle software are reviewed, and recent developments in each area are discussed.
25 November 2019 in IEEE Transactions on Intelligent Vehicles
In this paper we present a trajectory generation method for autonomous overtaking of unexpected obstacles in a dynamic urban environment. In these settings, blind spots can arise from perception limitations. For example when overtaking unexpected objects on the vehicle's ego lane on a two-way street. In this case, a human driver would first make sure that the opposite lane is free and that there is enough room to successfully execute the maneuver, and then it would cut into the opposite lane in order to execute the maneuver successfully. We consider the practical problem of autonomous overtaking when the coverage of the perception system is impaired due to occlusion. Safe trajectories are generated by solving, in real-time, a non-linear constrained optimization, formulated as a receding horizon planner that maximizes the ego vehicle's visibility. The planner is complemented by a high-level behavior planner, which takes into account the occupancy of other traffic participants, the information from the vehicle’s perception system, and the risk associated with the overtaking maneuver, to determine when the overtake maneuver should happen. The approach is validated in simulation and in experiments in real world traffic.
Mobile manipulators are nowadays popular in various fields, including military missions, civil defense, rescue, and social services. Along with the wide use of such robots, the associated control problems require more and more attention to the nonlinearity and uncertainties of the dynamic models. In this paper, targeting the challenges of trajectory control for applications in which the robots have to overcome complex terrain conditions, we present a rapid virtual prototyping using Matlab-Simulink with embedded design and implementation of two control strategies - feedforward nonlinear control and adaptive control for controlling the end-effector of a two-link robot arm with/without well-known models. Simulation results show the efficacy of the feedforward nonlinear controller and adaptive controller developed. Comparisons of the performances are made to provide an analytical evaluation as well as a general reference for selecting controllers in different cases.
When a vehicle observes another one, the two vehicles' poses are correlated by this spatial relative observation, which can be used in cooperative localization for further increasing localization accuracy and precision. To use spatial relative observations, we propose to add them into a pose graph for optimal pose estimation. Before adding them, we need to know the identities of the observed vehicles. The vehicle identification is formulated as a linear assignment problem, which can be solved efficiently. By using pose graph techniques and the start-of-the-art factor composition/decomposition method, our cooperative localization algorithm is robust against communication delay, packet loss, and out-of-sequence packet reception. We demonstrate the usability of our framework and effectiveness of our algorithm through both simulations and real-world experiments using three vehicles on the road.