Snake Aerial Manipulators: A Review <s> D. DESIGN CONSIDERATIONS OF ENERGY AND POWER <s> A tethered rotor platform is a special type of a rotary wing drone. Its dynamical behaviour is mainly determined by the interaction of the rotor, fuselage and tether. Starting from a discussion of the control and stabilization problems involved, the paper presents dynamical models of the plant with special emphasis on tether dynamics. These models were developed for the analysis of the dynamical behaviour of the vehicle and in particular for the design of an automatic hover control system (AHCS). Two approaches for the design of an AHCS are discussed. One uses optimal linear control theory and the other classical control techniques, resulting in a cascaded controller-structure for the various stabilization and guidance tasks. A discussion of the hardware realization, the measurement problems involved and results of actual flight tests with the designed AHCS are presented. <s> BIB001 </s> Snake Aerial Manipulators: A Review <s> D. DESIGN CONSIDERATIONS OF ENERGY AND POWER <s> Several research investigations have examined the challenges and opportunities in the use of small robotic rotorcraft for the exploration of Mars. To date, only vehicles smaller than 150 kg have been studied. This paper proposes to examine the question of maximum Mars rotorcraft size, range, and payload/cargo capacity. Implications for the issue of whether or not (from an extreme design standpoint) a manned Mars rotorcraft is viable are also discussed. <s> BIB002 </s> Snake Aerial Manipulators: A Review <s> D. DESIGN CONSIDERATIONS OF ENERGY AND POWER <s> In today's world, there is a continuous global need for more energy which, at the same time, has to be cleaner than the energy produced from the traditional generation technologies. This need has facilitated the increasing penetration of distributed generation (DG) technologies and primarily of renewable energy sources (RES). The extensive use of such energy sources in today's electricity networks can indisputably minimize the threat of global warming and climate change. However, the power output of these energy sources is not as reliable and as easy to adjust to changing demand cycles as the output from the traditional power sources. This disadvantage can only be effectively overcome by the storing of the excess power produced by DG-RES. Therefore, in order for these new sources to become completely reliable as primary sources of energy, energy storage is a crucial factor. In this work, an overview of the current and future energy storage technologies used for electric power applications is carried out. Most of the technologies are in use today while others are still under intensive research and development. A comparison between the various technologies is presented in terms of the most important technological characteristics of each technology. The comparison shows that each storage technology is different in terms of its ideal network application environment and energy storage scale. This means that in order to achieve optimum results, the unique network environment and the specifications of the storage device have to be studied thoroughly, before a decision for the ideal storage technology to be selected is taken. <s> BIB003 </s> Snake Aerial Manipulators: A Review <s> D. DESIGN CONSIDERATIONS OF ENERGY AND POWER <s> Preface 1 History of Aviation 1.1 Introduction 1.2 Early history and the invention of ballooning 1.3 The period between 1799 and 1870 1.4 The decades between 1870 and 1890 1.5 From 1890 until the Wright Flyer III 1.6 European aviation between 1906 and 1918 1.7 Aviation between the world wars 1.8 Development after 1940 Bibliography 2 Introduction to Atmospheric Flight 2.1 Flying - How is that possible? 2.2 Static and dynamic aviation 2.3 Forces on the aeroplane 2.4 Lift, drag and thrust 2.5 Properties of air 2.6 The earth's atmosphere 2.7 The standard atmosphere 2.8 Atmospheric flight Bibliography 3 Low-Speed Aerodynamics 3.1 Speed domains and compressibility 3.2 Basic concepts 3.3 Equations for steady flow 3.4 Viscous flows 3.5 The boundary layer 3.6 Flow separation and drag 3.7 Shape and scale effects on drag Bibliography 4 Lift and Drag at Low Speeds 4.1 Function and shape of aeroplane wings 4.2 Aerofoil sections 4.3 Circulation and lift 4.4 Aerofoil section properties 4.5 Wing geometry 4.6 High-aspect ratio straight wings 4.7 Low-aspect ratio wings 4.8 The whole aircraft Bibliography 5 Aircraft Engines and Propulsion 5.1 History of engine development 5.2 Fundamentals of reaction propulsion 5.3 Engine efficiency and fuel consumption 5.4 Piston engines in aviation 5.5 Gas turbine engine components 5.6 Non-reheated turbojet and turbofan engines 5.7 Turboprop and turboshaft engines 5.8 Gas turbine engine operation 5.9 Propeller performance Bibliography 6 Aeroplane Performance 6.1 Introduction 6.2 Airspeed and altitude 6.3 Equations of motion for symmetric flight 6.4 Steady straight and level flight 6.5 Climb and descent 6.6 Gliding flight 6.7 Cruising flight 6.8 Take-off and landing 6.9 Horizontal steady turn 6.10 Manoeuvre and gust loads Bibliography 7 Stability and Control 7.1 Flying qualities 7.2 Elementary concepts and definitions 7.3 Tail surfaces and flight control 7.4 Pitchingmoment of aerofoils 7.5 Static longitudinal stability 7.6 Dynamic longitudinal stability 7.7 Longitudinal control 7.8 Static lateral stability 7.9 Dynamic lateral stability 7.10 Lateral control 7.11 Stalling and spinning Bibliography 8 Helicopter Flight Mechanics 8.1 Helicopter general arrangements 8.2 Hovering flight 8.3 The rotor in level flight 8.4 Flight performance 8.5 Stability and control Bibliography 9 High-Speed Flight 9.1 Complications due to the compressibility of air 9.2 Compressible flow relationships 9.3 Speed of sound and Mach number 9.4 Flow in a channel 9.5 Shock waves and expansion flows 9.6 High-subsonic speed 9.7 Transonic speed 9.8 Supersonic speed 9.9 Supersonic propulsion 9.10 Performance and operation Bibliography A Units and Dimensions B Principles of Aerostatics Index <s> BIB004 </s> Snake Aerial Manipulators: A Review <s> D. DESIGN CONSIDERATIONS OF ENERGY AND POWER <s> Abstract The design, construction, and flight test of a fuel cell-powered small unmanned aircraft are described. A fuel cell system featuring a polymer electrolyte membrane fuel cell combined with a hydrogen generator, which serves as a new power source alternative to the existing batteries, is proposed. The hydrogen generator uses a catalytic hydrolysis reaction to extract hydrogen from an alkaline solution of sodium borohydride, and constructed with a reactor, pump, separator, and fuel cartridge. Considering the performance characteristics of the fuel cell, the hybrid power management of a fuel cell and a battery was contrived. The fuel cell stack, hydrogen generator, and power management system were evaluated at the various load conditions. A high efficiency unmanned aircraft was designed and fabricated to validate the possibility of the proposed fuel cell system, and a small flight control system was developed for a high endurance test flight. Wind-tunnel tests were conducted before the flight tests under actual flight conditions. The possibility for the utilization of a fuel cell in a small aircraft was validated through the fuel cell powered flight test. The fuel cell aircraft flew for 2 h without incidents in the fuel cell system. <s> BIB005 </s> Snake Aerial Manipulators: A Review <s> D. DESIGN CONSIDERATIONS OF ENERGY AND POWER <s> Traditional vertical take-off and landing micro aerial vehicles (VTOL MAVs) are generally underactuated, i.e., equipped with fewer actuators than degrees-of-freedom (DOF). As a consequence, they possess a limited mobility because of the inherent underactuation (e.g., they can neither translate laterally with a zero attitude nor hover at a spot with a nonzero attitude). In this paper, we present the design of a novel MAV, the Omnicopter, with two central counter-rotating coaxial propellers for thrust and yaw control and three perimeter-mounted variable angle ducted fans to control roll and pitch and provide lateral forces. It can work under two configurations, a fixed 90° ducted fan angle configuration and a variable angle ducted fan configuration. The variable angle configuration provides full actuation to the Omnicopter position/attitude. After a brief introduction of the Omnicopter platform, we discuss the control design, allocation and implementation for the two configurations separately. Simulations and experimental results verify the performance of the Omnicopter. <s> BIB006 </s> Snake Aerial Manipulators: A Review <s> D. DESIGN CONSIDERATIONS OF ENERGY AND POWER <s> Tethered aerial robots (TAR) that can be continuously powered by power cables for extended mission time and range are newly proposed. The TAR can overcome the limited mission time of conventional battery-based aerial vehicles and the mission range is quite extended with a virtue of a long aerial multi-wounded power cable. The TAR is equipped with an aerial contactless power system (ACPS) for avoiding the use of brush and an aerial tension control system (ATCS), first proposed in this paper, for avoiding tangled power cable. A prototype TAR including the ACPS and ATCS was developed and successfully demonstrated at outdoor environment, where the output power of 180 W at 100 kHz and a flight altitude of 20 m for 30 minutes were achieved. <s> BIB007 </s> Snake Aerial Manipulators: A Review <s> D. DESIGN CONSIDERATIONS OF ENERGY AND POWER <s> Abstract Advanced hybrid powerplants combining a fuel cell and battery can enable significantly higher endurance for small, electrically powered unmanned aircraft systems, compared with batteries alone. However, detailed investigations of the static and dynamic performance of such systems are required to address integration challenges. This article describes a series of tests used to characterise the Horizon Energy Systems' AeroStack hybrid, fuel-cell-based powertrain. The results demonstrate that a significant difference can exist between the dynamic performance of the fuel-cell system and its static polarisation curve, confirming the need for detailed measurements. The results also confirm that the AeroStack's lithium-polymer battery plays a crucial role in its response to dynamic load changes and protects the fuel cell from membrane dehydration and fuel starvation. At low static loads, the AeroStack fuel cell recharges the battery with currents up to 1 A, which leads to further differences with the polarisation curve. <s> BIB008 </s> Snake Aerial Manipulators: A Review <s> D. DESIGN CONSIDERATIONS OF ENERGY AND POWER <s> Abstract Solarcopter is a direct sunlight powered helicopter. It is a remote control quadcopter UAV able to continuously fly in sunlight without any need for energy storage. The prototype successfully flew under irradiance of 1000 W/m2 and achieved a thrust to weight ratio of 1.36:1. The Solarcopter is a proof of concept prototype demonstrating that the power required for helicopters can be obtained directly from sunlight. <s> BIB009 </s> Snake Aerial Manipulators: A Review <s> D. DESIGN CONSIDERATIONS OF ENERGY AND POWER <s> In this paper, new tethered aerial robots including roaming tethered aerial robots (RTARs) for radioactive material sampling and stationary tethered aerial robots (STARs) for environment monitoring are proposed to meet extremely-long-endurance missions of nuclear power plants. The flight of the proposed tethered aerial robots may last for a few days or even a few months as long as the tethered cable provides continuous power. A high voltage AC or DC power system was newly adopted to reduce the mass of the tethered cable. The RTAR uses a tethered cable spooled from the aerial robot and an aerial tension control system. The aerial tension control system provides the appropriate tension to the tethered cable, which is accordingly laid down on the ground as the RTAR roams. The STAR includes a tethered cable spooled from the ground and a ground tension control system, which enables the STAR to reach high altitudes. Prototypes of the RTAR and STAR were designed and successfully demonstrated in outdoor environments, where the load power, power type, operating frequency, and flight attitude of the RTAR and STAR were: 180 W, AC 100 kHz, and 20 m; and 300 W, AC or DC 100 kHz, and 80 m, respectively. <s> BIB010 </s> Snake Aerial Manipulators: A Review <s> D. DESIGN CONSIDERATIONS OF ENERGY AND POWER <s> Abstract This article discusses the design of an unmanned aerial vehicle whose purpose is to study the use of electric ducted fans as control and propulsion system. Thrust vectoring is essential for stabilizing the vehicle. We present measurement results characterizing the thrust vectoring capabilities of the propulsion system (both statically and dynamically), discuss a first-principle model describing the behavior of the flying machine, and analyze and quantify the controllability about hover. The first-principle model is subsequently used for a cascaded control design, which is shown to work reliably in practice. Furthermore, system identification results are discussed and used to extended the model. The resulting augmented model is shown to match the measured frequency response function. <s> BIB011 </s> Snake Aerial Manipulators: A Review <s> D. DESIGN CONSIDERATIONS OF ENERGY AND POWER <s> In this paper we present a novel concept of attitude control for a multi-rotor unmanned aerial vehicle by actively controlling its center of gravity. This research is a part of our efforts to build a heavy lift multi-rotor platform capable of carrying over 50 kg of payload. To that end, we propose using miniature two-stroke combustion engines to supply the necessary lift and combine them with moving masses used to control the vehicle attitude. In this paper we present a complete nonlinear dynamical model of such a vehicle and use it to derive the transfer functions of roll and pitch dynamics. Furthermore, we formulate a detailed root-locus based stability and sensitivity analysis of the proposed control scheme and discuss its underlining effect on the mechanical parameter design. We present the experimental testbed, consisted of the vehicle mounted on a 2 degrees of freedom gimbal, and derive necessary conditions for testbed parameters in order to match the testbed and free-flight quadrotor dynamics. Finally, we present simulation results from a Gazebo based simulator and experimental results of the testbed. Both results confirm the findings of our mathematical analysis. <s> BIB012 </s> Snake Aerial Manipulators: A Review <s> D. DESIGN CONSIDERATIONS OF ENERGY AND POWER <s> In this paper we present identification results of an internal combustion engine propulsion system. We aim to use this system in a large quadrotor designed to lift heavy objects with flight autonomy up to 60 minutes. In this paper we describe the testbed which we have built to perform the experiments. We present the static and dynamical characteristic of the propulsion system and discuss its dependence on the fuel-air mixture. In particular, we determine the static throttle-speed and speed-thrust curves. For dynamics analysis, we assume that the rotor dynamics can be represented by a PT 1 term and present its parameters for different engine regimes. Using the overall system transfer function we design a simple PI control of the rotor speed which assures setpoint tracking. Finally, we discuss if the achieved closed loop dynamics is suitable for attitude control of a large quadrotor. <s> BIB013 </s> Snake Aerial Manipulators: A Review <s> D. DESIGN CONSIDERATIONS OF ENERGY AND POWER <s> This paper exposes the Control technology embedded in a propeller propulsion for Unmanned Aerial Vehicle (UAV). The system relies on systems combining low-cost sensors, embedded controller and control algorithms based on aerodynamics models. Presented results are for standard propeller assignment and advanced assignment using the variable pitch propeller and its algorithms. <s> BIB014 </s> Snake Aerial Manipulators: A Review <s> D. DESIGN CONSIDERATIONS OF ENERGY AND POWER <s> Small satellites have seen an increase in recent years, and their use has been proposed in active space debris removal, which demands motors capable of high delta-Vs and precise attitude control. However, existing methods for attitude control impose relatively high mass and volume penalties when used for small-scale applications. Fluidic thrust vectoring is being investigated as a possible solution to this problem. The inverted pendulum problem was chosen to represent a highly simplified case of fluidic thrust vectoring in order to investigate how such a thrust vectoring method may be controlled, with the secondary aim of developing an educational tool for teaching control at UNSW Canberra introduced during the project. The system was simulated in MATLAB® Simulink™ to determine suitable control and hardware parameters for both PID and Fuzzy Logic Control, and two iterations of a physical system capable of achieving the calculated outputs were constructed. Both control methods were then demonstrated on each iteration with varying success. <s> BIB015 </s> Snake Aerial Manipulators: A Review <s> D. DESIGN CONSIDERATIONS OF ENERGY AND POWER <s> Flexible continuum robots exhibit a strong potential for approaching narrow and intricate spaces. However, such long flexible bodies often experience oscillations, making them unstable. To enhance their performance in order to realize rapid and precise movements, unnecessary vibrations should be suppressed. The authors have proposed a new type of continuum robot, aimed for firefighting; this robot, Dragon Firefighter (DFF), can fly using water jets. The DFF suffers from the same problem of body oscillation. In particular, a more challenging issue for the DFF is the use of limited number of actuators owing to the constraints of weight and water flow. Discrete locations of the actuators on the long body of a robot can generate uncontrollable resonant modes. This letter proposes a mechanical approach to suppress the oscillation passively without actuation control. The proposed mechanism is composed of wires threaded along the body and connected to rotary dampers to restrict the deformation of the body. First, a numerical model to simulate the oscillation and damping behavior was reported. A basic experiment with a 1-m-long flexible tube shows that the damping mechanism suppresses the vibration appropriately, which also corresponds well with the simulation. Second, a stability analysis of the simulation of the flying motion shows that the passive damping mechanism can improve the stability, with the convergence time becoming approximately 2.4 times shorter than that in the case without the mechanism. Finally, we apply the damping mechanism to a 3.6-m-long flying robot. The demonstration shows that the robot can float stably and that the damping mechanism works correctly. <s> BIB016
The snake aerial manipulators with our actual technology are feasible in three manners: By propellers: almost all the cases previously described have as reference, vehicles based on propellers, mainly by their cost of development and acquisition By valves: they are relatively new designs and instead of aircraft or propellers, they use a set of valves and pumps systematically commanded By turbines: the use of turbines is promoted because moving large masses or volumes involves a proportional change of propellers, however in turbines, the relation thrust vs propeller dimension is acceptable and not so abrupt, remarkable attempts to have mini turbine -drones with vertical take off and landing correspond to BIB011 , BIB006 (although they have been around for aeronautical and aerospace applications). It is also feasible to think of aircraft combining propeller technology and turbines such as turbojets (e.g. V-22 Osprey)  , BIB004 . Whatever the selected option, it will require a power source and according to commercially available sources of energy, there are four alternatives: fuel sources, solar sources, battery sources and direct wired connection (electrical or not like the pneumatic pump case). Table. 3 A serious problem to deal with aerial manipulation is power consumption. Consider, for example, an air-torso  , suppose that coaxial bicopters are used instead of quadrotors, in order to provide a waist, 2 shoulders and 2 elbows, 10 propellers will be required and their respective servo steering system, suppose that all the system without batteries or fuel weights 15kg and that it is required a capability of manipulation of another 10 kg at 50 m of altitude at least for 1 hour. Two problems arise from these suppositions: the first is related to power consumption, calculations show that at least 8000watts are required (e.g. MORUS project) BIB012 . In this manner the option for this power consumption and desired flight time are internal combustion engines BIB012   BIB013 if it is pretended to do a free flight. Or a direct electrical wire connection if it is not a drawback to fly anchored Fig. 9 [113]- BIB007 . The second problem is related with density of energy, actual batteries and solar cells needs huge volumes and spaces to provide enough power and flight time. In this way, despite the efforts and popularity, these sources of energy are not a viable option for practical long flight operations of snake aerial manipulators BIB009 BIB008 BIB005 BIB003 . As is noticed, the problems arise as consequence of size and mass, an useful dissertation to know when to refer to small or large scales is BIB002 Large scale: actual approaches of MM-UAV are not feasible in large scale aircrafts, for example, researchers that change the direction of rotation of the propellers for faster control of orientation, must deal with the counterpart in big scale UAVs where this change is slow and dangerous. The approach of tilting the entire body of a propeller and its corresponding motor is also not feasible, because the required engine capable of moving a rotating propeller, demand too much power, because they work against considerable gyroscopic and inertial effects In this way is needed to develop snake aerial manipulators focused on turbine thrust vectoring methods (in fact, the propeller technology becomes oversized) or work in new ways for varying the angle of attack of the propellers with swashplates or another methods including non-mechanical BIB014 BIB015  , of course, if it is even possible to use propellers. Discussion: This section has dealt with the relationship of power and scale, the existing approaches for this high-power consumption technology, are internal combustion engines and power-tethered sources, being this last one and at least to the date, the one with the greatest impact and development. As indicated in the Table. 3, the research to be developed is to determine the best modes of operation and control for tethered and wireless power supplies (including on-board power supplies such as batteries). Currently by the technological effects of energy density and power density, the most adequate supplies seem to be the tethered ones, but said anchors impose restrictions of operation in terms of mobility (radial geometries due to the cable and for the purpose of not self-entanglement with the vehicle) and also force restrictions (in order to avoid breaking said umbilical cord) BIB010 , BIB001 . For long-time operation wireless power supplies, as on-board fuel tanks, research is still under development, the current research works in the response times of the actuators, because by the action of sprinklers mechanism for fuel injection, they have slower response times than the obtained by using electric motors BIB012   . Therefore, it seems that the most convenient snake aerial manipulators are those powered by electricity, however, this implies short flight operations to ensure a thermal rest of the motors or to carry cooling systems as heatsinks or fans (these motors can be optimized such that the same propellers cool them). On the other hand recent approaches have found new methods as power supplies, for example, and even though that its power efficiency has not yet been studied, the snake aerial manipulator based on regulated hydraulic jets has an immediate application as intelligent or controllable fire hose BIB016 . Finally, the characteristic that will determine or will help to determine efficiencies and applications is the size of the aircraft. As suggested, some methods for vectorization and power supplies are physically unthinkable for large scale aircraft, while for smaller dimensions and weights, there are more possibilities but more restricted applications (there are more methods but as a consequence of the size there is also less force or mobility to make any possible interaction with the environment or with themselves).