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This paper considers optimal trajectory planning for autonomous nonholonomic vehicles used in investigating environmental phenomena. In particular, we present an algorithm that generates locally optimal trajectories to find the global maximum of the underlying environmental field. Our algorithm uses Gaussian process priors to estimate the unknown field and the notion of expected improvement to develop...
This paper details a method to ascertain the reachability of known emergency landing sites for any fixed wing aircraft in a forced landing due to engine failure in steady uniform wind conditions. With knowledge of the aircraft's state and parameters, and landing site location and landing direction, the minimum height loss path can be defined. This uses glide performance calculations and a trajectory...
This paper presents a system for collision-free trajectory planning with multiple Unmanned Aerial Vehicles (UAVs) which automatically identifies conflicts among them. After detecting conflicts between UAVs, the system resolves them cooperatively using a collision-free trajectory planning algorithm based on a stochastic optimization technique named Particle Swarm Optimization (PSO). The new implementation...
This paper describes the theory and implementation of a trajectory optimization layer operating within an energy-aware, airborne, dynamic data-driven application system (EA-DDDAS). The work addresses wind field data estimation, trajectory optimization, and implementation of communication protocols to increase sUAS endurance in persistent sensing missions. The trajectory optimization layer acts as...
In this article, we proposed a framework to realize vision based multi-UAV cooperative mapping and control with image based visual servoing (IBVS). Equipped with a camera on each UAV platform respecitively, the multi-UAV system with overlapping camera field of view (FOV) can achieve ground mapping and formation cooperatively by image information interaction. Initially, we introduce the Multi-UAV system...
This paper presents a trajectory tracking controller for multi-rotor UAVs to improve their flight performance in the presence of various uncertainties. The proposed tracking system consists of a velocity guidance law based on relative distance and an L1 adaptive augmentation loop for tracking velocity commands. In the proposed structure, the desired velocity generated by the guidance law is the reference...
This work presents the design of an open-source control architecture specifically tailored to the rapid development and testing of control and coordination algorithms on micro quadrotors. The proposed design extends an existing open-source and open-hardware quadrotor project, i.e., the Crazyflie nano quadrotor, by adding the guidance, navigation and control layers required to accomplish autonomous...
This paper considers the control of a multirotor-type unmanned aerial vehicle (UAV) with a suspended load. The load is modeled as a pendulum, with a rigid link. We consider the case when the suspended load is connected to the centre of gravity of the UAV, and the interconnected system is modeled by Kane's method. A nonlinear controller based on the backstepping technique is derived, that ensures trajectory...
This article is focused on the trajectory tracking using a hybrid terrestrial aerial vehicle. An integral backstepping control is proposed for the UAV vehicle mode. In addition, a nested saturation control is developed and applied to regulate the position of the cart vehicle. These control laws are validated by simulations and some experimental results on position control was performed by applying...
This paper presents implementation of a novel guidance logic for multi-agent fixed-wing unmanned aerial systems using a moving mesh method. The moving mesh method is originally designed for use in the adaptive numerical solution of partial differential equations where a high proportion of mesh points are placed in the regions of large solution variation and few points in the rest of the domain. In...
This paper presents a real-time path planning algorithm for UAVs to avoid collision with other aircraft. Reachable sets are used to represent the collection of possible trajectories of obstacle aircraft. It is used in collision prediction for UAVs in path planning. Once a collision is detected, a sampling-based method is used to generate a collision avoidance path. A second collision check is performed...
In this paper we propose a novel approach for trajectory optimization for constrained Unmanned Aerial Vehicles (UAVs). With regard to the classical trajectory optimization problem, we take a Virtual Target Vehicle (VTV) perspective by introducing a virtual target that plays the role of an additional control input. Based on a nonlinear projection operator optimal control technique and extending the...
Motion control of UAVs is an interesting problem due to the nonlinear and underactuacted nature of their dynamics. This paper focuses on position and yaw control of a rotary-wing UAV with state and input constraints using an inner-outer loop control structure. The outer loop generates saturated thrust and reference roll and pitch angles, while the inner loop is designed to follow the reference angles...
A monocular vision-based approach to indoor autonomous navigation for an off-the-shelf, low-cost Micro Air Vehicle (MAV) quadcopter is presented. Our approach is fully automated and relies on the extraction and analysis of the visual contours of the surrounding physical environment to successfully steer the MAV in hallways and to turn at intersections. All image analysis and processing necessary for...
Aerial vehicle landing is an open and challenging problem. This paper focuses on development of simple guidance laws for quadrotor landing with known GPS location - stationary and moving. The guidance laws are based on missile guidance principles, namely pure pursuit, line-of-sight, and pure proportional navigation. Comparison on the performance of these guidance laws is presented through Matlab simulations...
This paper presents the algorithms enabling real-time 4-Dimensional Flight Trajectory (4DT) functionalities in Next Generation Mission Management Systems (NG-MMS), which are the core element of future Remotely Piloted Aircraft Systems (RPAS) avionics. In particular, the algorithms are employed for multi-objective optimisation of 4DT intents in various operational scenarios spanning from online strategic...
This paper reports the results of the UNIZG-FER team in the third European Robotics Challenge (EuRoC). More precisely, the results of the 1st qualifying stage of the challenge where a micro aerial vehicle (MAV) is tested in realistic simulation scenarios. The paper presents the entire controller setup, starting from the power distribution level, low level cascade controllers with wind disturbance...
This paper presents the key design features, the numerical simulations and the experimental ground/flight test activities performed to verify the functionalities of an obstacle detection and avoidance system suitable for various classes of manned and unmanned aircraft. The Laser Obstacle Avoidance and Monitoring (LOAM) system is proposed as one of the key non-cooperative sensors adopted for avoiding...
This article proposes a methodology for enabling Unmanned Aircraft Systems (UASs) to avoid obstacles. The strategy, which makes use of a Robust Exact Differentiation (RED), relies on spiral trajectory tracking maneuvers, and is based on a backstepping controller with disturbance compensation. The RED strategy has been adopted since it enables the exact estimation of disturbances from the first moment,...
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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