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Near-earth environments, such as forests, caves, tunnels, and urban structures make reconnaissance, surveillance and search-and-rescue missions difficult and dangerous to accomplish. Micro-air-vehicles (MAVs), equipped with wireless cameras, can assist in such missions by providing real-time situational awareness. This paper describes an additional...
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... four forces of flight acting on the aircraft dur- ing this large angle-of-attack maneuver are lift (L), weight (W ), thrust (T ) and drag (D) (see Figure 4). Summing the forces parallel and perpendicular to the flight path, which is opposite to the free-stream ve- locity, yields the following two equations ...
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In the last years, there has been lots of investigation on the aerodynamics of flapping wing micro air vehicles. By analysing the flapping mechanics of natural flyers like birds and insects, human made robotical unmanned aircrafts are manufactured. In general, the works which investigates the flows at low Reynolds numbers covers both the biological...
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... For example, a number of researchers [14,15,27,32,38] have developed various hover maneuver controllers that can handle the autonomous transition from steady level flight to a hovering position, which mainly based on PID control, Model Predictive Control (MPC) and Time-Varying Linear Quadratic Regulator (TVLQR). While these approaches were able to successfully fulfill the hovering task, they cannot capture the aggressiveness of truly aerobatic flight. ...
... The values of states can be obtained from JSBSim, and then the reward is calculated according to states in s E using Eq. (15). Subsequently, the reward and states are fed to PPO for training. ...
Autonomous agile flight control has been a challenging problem due to complex highly nonlinear dynamics, and generating feasible basic flight maneuvers off-line for subsequent online motion planning has become a solution. In this paper, we present a novel reinforcement learning-based basic flight maneuvers generation method for a 6 degrees of freedom aircraft model via Proximal Policy Optimization (PPO). Different from traditional control methods depending on model simplification or complex controller design, the proposed algorithm can automatically generate maneuvers by directly selecting different aircrafts and adding or subtracting reward components. First, we propose a new approach to ensure the continuity and avoid large oscillations of the control command by designing its time derivative as the output of policy network and then using the integral operator to obtain the final control action exerted to the plane, which is effective to achieve complex flight control tasks based on the aircraft model with high-fidelity. Second, the reward function used in PPO training is comprised of desired aims of which the weights can be adaptive according to the task type or conditional trigger during training. By this method, we successfully generate most of the basic flight maneuvers, including level flight, coordinated turn, climb/descent and horizontal roll. A series of simulation results show that our proposed algorithm can not only learn these maneuvers in a short time within 0.2–10 h but also has superior performance in settling time and robustness compared with the traditional PID control method while attaining similar accuracy.
... • examine microbial life of tellurian caves as Mars analogs (e.g., Boston, 2004;Boston et al., 2006;Léveillé & Datta, 2010;Röling et al., 2015;Selensky et al., 2021;Westall et al., 2015); • model environments of terrestrial and potential martian cave systems (e.g., Schörghofer et al., 2018;Titus et al., 2010;Williams & McKay, 2015;Williams et al., 2010); • improve cave detection capabilities (e.g., Cushing et al., 2015;Hong et al., 2015;Pisani & De Waele, 2021;Wynne et al., 2008Wynne et al., , 2021); • develop and expand upon life detection instrumentation and techniques (e.g., Patrick et al., 2012;Preston et al., 2014;Storrie-Lombardi et al., 2011;Uckert et al., 2020); • expand the number of cave explorer robotic platforms under development (Green & Oh, 2005;Kesner et al., 2007;Morad et al., 2019;Nesnas et al., 2012;Parness et al., 2017;Titus, Wynne, Boston, et al., 2021;Titus, Wynne, Malaska, et al., 2021); • advance robotic sensing and navigational capabilities (e.g., Agha-Mohammadi et al., 2021;Kalita et al., 2017;Kim et al., 2021;Thakker et al., 2021); and, • propose mission concepts (e.g., Kerber et al., 2019;Phillips-Lander et al., 2020;Whittaker et al., 2021;Ximenes et al., 2012) and strategies to optimize future planetary cave exploration efforts (e.g., Rummel et al., 2014;Titus, Wynne, Boston, et al., 2021;Titus, Wynne, Malaska, et al., 2021;Wynne et al., 2014;Wynne, Titus, et al., 2022). values. ...
We provide the first solar system wide compendium of speleogenic processes and products. An examination of 15 solar system bodies revealed that six cave‐forming processes occur beyond Earth including volcanic (cryo and magmatic), fracturing (tectonic and impact melt), dissolution, sublimation, suffusion, and landslides. Although no caves (i.e., confirmed entrances with associated linear passages) have been confirmed, 3,545 SAPs (subsurface access points) have been identified on 11 planetary bodies and the potential for speleogenic processes (and thus SAPs) was observed on an additional four planetary bodies. The bulk of our knowledge on extraterrestrial SAPs is based on global databases for the Moon and Mars, which are bodies for which high‐resolution imagery and other data are available. To further characterize most of the features beyond the Moon and Mars, acquisition (preferably global coverage) and subsequent analysis of high‐resolution imagery will be required. The next few decades hold considerable promise for further identifying and characterizing caves across the solar system.
... Academia, private, and government entities have been developing autonomous navigation systems for sea [1], land [2], air [3], and space [4] to improve safety and efficiency for decades. To date, robust systems have been achieved in each of these domains with the glaring exception of on-road autonomous vehicles (AVs) due to the greater complexity of the driving environment [5]. ...
Commercialization of autonomous vehicle technology is a major goal of the automotive industry, thus research in this space is rapidly expanding across the world. However, despite this high level of research activity, literature detailing a straightforward and cost-effective approach to the development of an AV research platform is sparse. To address this need, we present the methodology and results regarding the AV instrumentation and controls of a 2019 Kia Niro which was developed for a local AV pilot program. This platform includes a drive-by-wire actuation kit, Aptiv electronically scanning radar, stereo camera, MobilEye computer vision system, LiDAR, inertial measurement unit, two global positioning system receivers to provide heading information, and an in-vehicle computer for driving environment perception and path planning. Robotic Operating System software is used as the system middleware between the instruments and the autonomous application algorithms. After selection, installation, and integration of these components, our results show successful utilization of all sensors, drive-by-wire functionality, a total additional power* consumption of 242.8 Watts (*Typical), and an overall cost of $118,189 USD, which is a significant saving compared to other commercially available systems with similar functionality. This vehicle continues to serve as our primary AV research and development platform.
... Hereby, u F denotes the total thrust parallel to the main body axis, while u Mi are roll, pitch and yaw moment respectively. Since the matrix M in (28) has full rank, the actuator commands ω c can be easily computed from the controller output u c as: (29) which was used in [88,73]. ...
This paper provides a broad perspective and analysis of the work done in control of hybrid and convertible unmanned aerial vehicles (UAVs) for the main existing designs. These flying machines are capable of vertical take off and landing (VTOL) in helicopter mode and able to transition to high-speed forward flight in airplane mode and vice versa. This paper aims at helping engineers and researchers develop flight control systems for VTOL UAVs. To this end, a historical perspective first shows the technological advances in VTOL aircraft over the years. The main VTOL concepts and state-of-art flight control methods for VTOL UAVs are presented and discussed. This study shows both the common parts and the fundamental differences in the modeling, guidance, control, and control allocation for each hybrid-VTOL-UAV type. The open challenges and the current trends in the field are highlighted. These are namely: 1) augmenting or replacing classical controllers with data-driven methods such as neural networks and machine-learning-based controllers; 2) incorporating as much knowledge of the vehicle as possible into the flight controller, for example through model predictive control or model-based nonlinear controllers; 3) a trend towards finding a unified-control approach valid in all flight modes without the need to switch among flight controllers or to perform predefined-gain scheduling, and 4) the need to mitigate control complexity and available computing resources.
... Endurance is a major focus, directly influencing the maximum range. Helicopters typically have about half the endurance of fixed-wing craft [23] and have benefitted from decades of propulsion system research and development [24]. Although helicopter configurations are still used for large unmanned systems their use in smaller systems has diminished due to the complexity and maintenance requirements of collective pitch rotor systems [25]. ...
The backdrop to the rapidly expanding use of drones is described, including development of drone technology, followed by an overview of current civilian use, focusing on use in and around the urban environment. The inhibitors to further use are considered including technological and societal aspects. The operation and control issues are reviewed including autonomous or semi-autonomous operation. Issues of lack of regulation, safety, lack of endurance/payload, noise, inability to fly well in adverse weather are considered. Research into how these issues may be overcome is discussed and comparisons are drawn with how equivalent-sized natural flyers (bird and larger flying insects) cope within the urban environment are made. The paper concludes with an overview of possible and planned use in the urban environment.
... Fixed wing drones usually require a thrust loading less than one and less power to fly than a helicopter with the same weight in hovering mode [88,89]. In larger drones, the lift over drag ratio is more than 30 [88]. ...
... All types of rotorcraft must rely solely on their rotors to produce sufficient thrust to overcome weight for hover or climb. Rotary wing aircraft typically have about half the endurance of fixed wings of the same weight with a moderate lift/drag ratio (L/D) of four (Green and Oh, 2005). Endurance is heavily influenced by disk loading, which is defined as the weight per area swept by the rotor. ...
... The operation of hybrid VTOL vehicles during hover and forward flight may require different sets of flight control strategies, making the control design very challenging. The commonly studied hybrid VTOL concepts in the literature include monoplane wing tail-sitter [1][2][3][4], tiltrotor [5,6], compound helicopter, quad tiltrotor [7], and quad-tiltwing [8] concepts. The monoplane tail-sitter concept has the simplest design, but it suffers from poor control authority during hover due to use of a solitary propeller. ...
This paper presents the development of 6-degrees-of-freedom (6-DOF) flight dynamics model and nonlinear control design for a novel hybrid biplane-quadrotor unmanned aerial vehicle capable of efficient operation in both vertical takeoff and landing (VTOL) mode and forward flight mode. The development of vehicle dynamics model considers a complete description of flight dynamics, wing aerodynamics, and prop wash modeling. Rotor and wing aerodynamics during hover, transition, and forward flight are the key components of the vehicle dynamics equations and are systematically validated with experimental data available in the literature. The rotor aerodynamic loads calculated using blade element theory and uniform inflow–based model is found to offer adequate fidelity during both axial and edgewise flights of the rotor. The rigid body rotation of 90° about pitch axis during transition from hover to forward flight and back necessitates the use of quaternions for representation of the attitude of the vehicle to avoid singularity associated with Euler angles for such maneuvers. A comprehensive nonlinear control design using dynamic inversion approach is developed for the whole flight regime that includes climb/descent, hover, transition, and forward flight. The performance of the proposed control design is demonstrated through numerical simulations on the 6-DOF model of the vehicle.
... A simple mechanism is preferable for UAV, because weight saving is crucial for the VTOL maneuver. Several types of tail-sitter UAVs have been developed (Stone 1999;Taylor et al. 2003;Green and Oh 2005;Frank et al. 2007; Kita et al. 2009). However, because the fixed-wing becomes dead-weight during hovering, payload capacities of these tail-sitter aircrafts are smaller than that of a rotarywing aircraft or conventional fixed-wing aircraft. ...
A quadrotor equipped with a fixed-wing (hereinafter referred to as the quadrotor tail-sitter UAV) has been developed by authors. The quadrotor tail-sitter UAV can hover like a quadrotor and can fly like a fixed-wing airplane. The remarkable characteristic of the developed quadrotor tail-sitter UAV is that it does not use any control surfaces during any form of flight; hovering, transition flight or level flight. This paper discusses an optimal transition from hovering to level flight for the quadrotor tail-sitter UAV because transition flight is most likely to be unstable throughout flight owing to stalling of the fixed-wing. The paper proposes three transition strategies: (i) normal transition (PID feedback to a step input), (ii) minimizing the transition time, and (iii) minimizing the transition time with keeping altitude constant. To realize the above optimal transition strategies, the aerodynamic parameters of the developed quadrotor tail-sitter UAV are measured by the wind tunnel test in advance. The three strategies are experimentally verified and the comparison among the three strategies is presented.
... These drones can be used in various types of missions where the high speed is required, such as flying over water and forests. Fixed wing drones usually require a thrust loading less than one and less power to fly than a helicopter with the same weight in hovering mode [239,240]. In larger drones, the lift over drag ratio is more than 30 [239]. ...
Nowadays, there is a growing need for flying drones with diverse capabilities for both civilian and military applications. There is also a significant interest in the development of novel drones which can autonomously fly in different environments and locations and can perform various missions. In the past decade, the broad spectrum of applications of these drones has received most attention which led to the invention of various types of drones with different sizes and weights. In this review paper, we identify a novel classification of flying drones that ranges from unmanned air vehicles to smart dusts at both ends of this spectrum, with their new defined applications. Design and fabrication challenges of micro drones, existing methods for increasing their endurance, and various navigation and control approaches are discussed in details. Limitations of the existing drones, proposed solutions for the next generation of drones, and recommendations are also presented and discussed.
