Fixed-wing unmanned aerial vehicles (UAVs) can be an essential tool for low-cost aerial surveillance and mapping applications in remote regions. There is, however, a key limitation, which is the fact that low-cost UAVs have limited fuel capacity and, hence, require periodic refueling to accomplish a mission. Moreover, the usual mechanism of commanding the UAV to return to a stationary base station for refueling can result in the fuel wastage and inefficient mission operation time. Alternatively, one strategy could be the use of an unmanned ground vehicle (UGV) as a mobile refueling unit, where the UAV will rendezvous with the UGV for refueling. In order to accurately perform this task in the presence of wind disturbances, we need to determine an optimal trajectory in three-dimensional taking UAV and UGV dynamics and kinematics into account. In this paper, we propose an optimal control formulation to generate a tunable UAV trajectory for rendezvous on a moving UGV that also addresses the possibility of the presence of wind disturbances. By a suitable choice of the value of an aggressiveness index that we introduce in our problem setting, we are able to control the UAV rendezvous behavior. Several numerical results are presented to illustrate the reliability and effectiveness of our approach.

In this paper we address the minimum lap-time problem for a single-track rigid car which includes tire models and load transfer. Given a planar track including lane boundaries, our goal is to find a trajectory of the car minimizing the lap time subject to tire and steering limits. By using a new set of coordinates, the time-dependent system is transformed into a “space-dependent” (and space-variant) system. The choice of a suitable set of coordinates and the partition of the dynamics into a “longitudinal” one and a “transverse” one, allows us to convert the minimum time problem into a fixed horizon constrained optimal control problem. Based on a projection operator nonlinear optimal control technique, we propose a minimum lap-time strategy to push the rigid car to the limit of its handling capabilities. Finally, we provide numerical computations that: (i) show the effectiveness of the proposed strategy, and (ii) allow us to highlight important features of minimum lap-time trajectories.

In this brief, we provide optimal control-based strategies to explore the dynamic capabilities of a single-track car model that includes tire models and longitudinal load transfer. First, we propose numerical tools to analyze the equilibrium manifold of the vehicle. That is, we design a continuation and predictor-corrector numerical strategy to compute the cornering equilibria on the entire range of operation of the tires. Second, as a main contribution of this brief, we explore the system dynamics by the use of nonlinear optimal control techniques. Specifically, we propose a combined optimal control and continuation strategy to compute aggressive car trajectories. To show the effectiveness of the proposed strategy, we compute aggressive maneuvers of the vehicle inspired to testing maneuvers from virtual and real prototyping.