Snake Aerial Manipulators: A Review <s> F. DESIGN CONSIDERATIONS ACCORDING TO THE THRUSTER AUTONOMY <s> Since the original publication of Helicopter Dynamics by A.R.S. Bramwell in 1976, this book has become the definitive text on helicopter dynamics. As such it is an essential aid to those studying the behavior of helicopters. The second edition builds on the strengths of the original, and hence the approach of the first edition is retained. The authors provide a detailed summary of helicopter aerodynamics, stability, control, structural dynamics, vibration, and aeroelastic and aeromechanical stability. <s> BIB001 </s> Snake Aerial Manipulators: A Review <s> F. DESIGN CONSIDERATIONS ACCORDING TO THE THRUSTER AUTONOMY <s> The steering system on a micro helicopter is the key element for control and navigation. For a sufficient control authority the steering has to be fast, precise, reliable and lightweight. While on full scale helicopters the choice of the steering mechanism is limited, there exist many possibilities to steer a helicopter in small scale. In this paper a survey on different concepts is given followed by a realization on the coaxial micro helicopter muFly. The mechanism uses piezoelectric actuation and a simplified swash plate to apply cyclic pitch and thus maneuver the Micro Air Vehicle. <s> BIB002 </s> Snake Aerial Manipulators: A Review <s> F. DESIGN CONSIDERATIONS ACCORDING TO THE THRUSTER AUTONOMY <s> Whenever the realization of a swash plate mechanism is not feasible (e.g. due to miniaturization limitations), center of gravity steering is an interesting alternative to swash plate steering. We present an approach to describe the dynamic behavior of a coaxial micro helicopter steered by a center of gravity shifting mechanism. The mechanical design of an existing system is improved to increase mechanical robustness and steering quality. In parallel, a simulation model is developed and implemented. It is used to estimate the system response to steering inputs, and to compare center of gravity to swash plate steering. Experimental flight results show an improvement of the helicopter performance due to the mechanical redesign. <s> BIB003 </s> Snake Aerial Manipulators: A Review <s> F. DESIGN CONSIDERATIONS ACCORDING TO THE THRUSTER AUTONOMY <s> Abstract In this paper, the design of two prototypes of the autonomous micro helicopter muFly is introduced. These prototypes have been built and flown in untethered test flights. The rotor configuration and steering principle selection of the prototypes are discussed according to the specifications, and the selection of a coaxial configuration with a swash plate steering of the lower rotor is justified based on dynamic simulation results. The two prototype designs are shown and discussed with special attention paid to their respective system integration issues, which are solved. Finally, the prototypes are compared and conclusions for future designs of autonomous micro helicopters are drawn. <s> BIB004 </s> Snake Aerial Manipulators: A Review <s> F. DESIGN CONSIDERATIONS ACCORDING TO THE THRUSTER AUTONOMY <s> Unmanned Rotorcraft Systems explores the research and development of fully-functional miniature UAV (unmanned aerial vehicle) rotorcraft, and provides a complete treatment of the design of autonomous miniature rotorcraft UAVs. The unmanned system is an integration of advanced technologies developed in communications, computing, and control areas, and is an excellent testing ground for trialing and implementing modern control techniques. Included are detailed expositions of systematic hardware construction, software systems integration, aerodynamic modeling; and automatic flight control system design.Emphasis is placed on the cooperative control and flight formation of multiple UAVs, vision-based ground target tracking, and landing on moving platforms. Other issues such as the development of GPS-less indoor micro aerial vehicles and vision-based navigation are also discussed in depth: utilizing the vision-based system for accomplishing ground target tracking, attacking and landing, cooperative control and flight formation of multiple unmanned rotorcraft; and future research directions on the related areas. <s> BIB005 </s> Snake Aerial Manipulators: A Review <s> F. DESIGN CONSIDERATIONS ACCORDING TO THE THRUSTER AUTONOMY <s> This paper presents the work that has been done to derive an accurate nonlinear model for a miniature fixed-pitch coaxial helicopter. Starting from the Newton-Euler rigid body dynamic equations, forces and torques generated at various parts of the UAV have been identified and formulated. The physical meanings behind the model are clearly explained, and the methods of identifying all the important model parameters are also provided. The full model is verified by comparing simulation results and actual flight tests with the NUS FeiLion coaxial UAV. The agreement between the two is promising. <s> BIB006 </s> Snake Aerial Manipulators: A Review <s> F. DESIGN CONSIDERATIONS ACCORDING TO THE THRUSTER AUTONOMY <s> The Handbook of Unmanned Aerial Vehicles is a reference text for the academic and research communities, industry, manufacturers, users, practitioners, Federal Government, Federal and State Agencies, the private sector, as well as all organizations that are and will be using unmanned aircraft in a wide spectrum of applications. The Handbook covers all aspects of UAVs, from design to logistics and ethical issues. It is also targeting the young investigator, the future inventor and entrepreneur by providing an overview and detailed information of the state-of-the-art as well as useful new concepts that may lead to innovative research. The contents of the Handbook include material that addresses the needs and know how of all of the above sectors targeting a very diverse audience.The Handbook offers a unique and comprehensive treatise of everything one needs to know about unmanned aircrafts, from conception to operation, from technologies to business activities, users, OEMs, reference sources, conferences, publications, professional societies, etc. It should serve as a Thesaurus, an indispensable part of the library for everyone involved in this area. For the first time, contributions by the worlds top experts from academia, industry, government and the private sector, are brought together to provide unique perspectives on the current state-of-the-art in UAV, as well as future directions. The Handbook is intended for the expert/practitioner who seeks specific technical/business information, for the technically-oriented scientists and engineers, but also for the novice who wants to learn more about the status of UAV and UAV-related technologies.The Handbook is arranged in a user-friendly format, divided into main parts referring to: UAV Design Principles; UAV Fundamentals; UAV Sensors and Sensing Strategies; UAV Propulsion; UAV Control; UAV Communication Issues; UAV Architectures; UAV Health Management Issues; UAV Modeling, Simulation, Estimation and Identification; MAVs and Bio-Inspired UAVs; UAV Mission and Path Planning; UAV Autonomy; UAV Sense, Detect and Avoid Systems; Networked UAVs and UAV Swarms; UAV Integration into the National Airspace; UAV-Human Interfaces and Decision Support Systems; Human Factors and Training; UAV Logistics Support; UAV Applications; Social and Ethical Implications; The Future of UAVs. Each part is written by internationally renowned authors who are authorities in their respective fields.The contents of the Handbook supports its unique character as a thorough and comprehensive reference book directed to a diverse audience of technologists, businesses, users and potential users, managers and decision makers, novices and experts, who seek a holistic volume of information that is not only a technical treatise but also a source for answers to several questions on UAV manufacturers, users, major players in UAV research, costs, training required and logistics issues. <s> BIB007 </s> Snake Aerial Manipulators: A Review <s> F. DESIGN CONSIDERATIONS ACCORDING TO THE THRUSTER AUTONOMY <s> A tilt-quad rotor is a fusion of the quad rotor and tiltrotor concepts. A tilt-quad rotor is able to move itself in all six degrees of freedom while maintaining its central core leveled, result of adding two tilting motions to two opposed rotors while the other two rotors remain fixed. Condensing the main information required to build a simulator, this paper presents the tilt-quad rotor original concept, its implementation in the ALIV3 prototype, and its modeling. The procedures and results of a thorough experimental identification of the structural, actuators and sensors parameters are also provided. <s> BIB008 </s> Snake Aerial Manipulators: A Review <s> F. DESIGN CONSIDERATIONS ACCORDING TO THE THRUSTER AUTONOMY <s> We have developed a robot with a new control mechanism in order to collect information on flying robots in multiple fields. We aimed for a function that could rotate the tilt angle continuously and without limit and a function for flying maintaining any desired tilt angle with a structure that could efficiently use the thrust generated by the propellers. We devised a mechanism that connected two bicopter modules, each of which combines two of the four propellers into one set and named this mechanism the “Bi2 Copter”. This mechanism provided movements including landing, take-off, and flying with any desired tilt angle. This ability of this mechanism to fly walls with continuously changing surface angles and full 360° spherical coverage makes possible applications in investigation, measurement, etc. This report covers the design concepts of this flying robot, the structure design, basic control and operations verification. <s> BIB009 </s> Snake Aerial Manipulators: A Review <s> F. DESIGN CONSIDERATIONS ACCORDING TO THE THRUSTER AUTONOMY <s> A comprehensive mathematical model of a coaxial helicopter’s swashplate mechanism is established, analyzed and verified in this paper. The mechanism widely used in helicopters to manipulate blade pitch angles is complex because of its configuration of multi closed-loop kinematic chains, especially for coaxial layout. First, geometrical method is used in determining the direct and inverse position kinematics. Based on that model, an approach of differentiation on spatial vectors is adopted to induce the relative velocity and acceleration matrices of every part of the system. The influence of rotors’ rotation is also considered in the modeling of velocity and acceleration kinematics to obtain a comprehensive model. The workspace and dexterity characteristics are analyzed in detail under the constraint of actuators’ inputs. After that, the complete direct kinematic model is simulated with consideration of control allocation and actuator dynamics. Finally, an integrated verification approach is designed based... <s> BIB010 </s> Snake Aerial Manipulators: A Review <s> F. DESIGN CONSIDERATIONS ACCORDING TO THE THRUSTER AUTONOMY <s> In this paper, we introduce a novel type of the multirotor aerial vehicle with two-dimensional multilinks which enables the stable aerial transformation for high mobility in three-dimensional environments. Our goal is to hold and carry object by using the whole-body manipulation in the air. The research involved three steps. First, we developed the modeling of the link modules that compose a multirotor with two-dimensional multilinks and conducted a quadrotor prototype. Second, we derived a stable flight control method for aerial transformation on the basis of linear-quadratic-integral optimal control. Third, we investigated the whole-body aerial manipulation based on the enveloping grasping method for the four-link type which takes the additional inertial parameters and joint torque into account. Successful aerial transformation and manipulation with the quadrotor prototype were demonstrated, confirming the feasibility of our proposed transformable multirotor for aerial maneuvering. <s> BIB011 </s> Snake Aerial Manipulators: A Review <s> F. DESIGN CONSIDERATIONS ACCORDING TO THE THRUSTER AUTONOMY <s> Abstract In this paper, the application of the principle of virtual work to the inverse dynamic modelling of a coaxial helicopter’s swashplate mechanism is discussed. The swashplate mechanism is always designed as a configuration of multi closed-loop kinematic chains which dynamics is difficult to be analyzed, especially for coaxial layout. Firstly, the whole mechanism is decomposed into two submodules, the lower one and the middle-upper one, with driving torques of actuators and aerodynamic hinge moments as the input to each submodule respectively. After derivation of Jacobian matrices for the main components, the equations of equilibrium about the two submodules are constructed based on the principle of virtual work and then combined to achieve the complete inverse dynamic model. Furthermore, an integrated actuating system model for coaxial helicopter is established by combining the inverse dynamic model with mechanism kinematics, rotor dynamics, actuator dynamics and command allocation. Based on that model, an efficient approach to load analysis for actuators of helicopter in flight is created. Finally, a series of simulation for load analysis of actuators is performed. <s> BIB012
Autonomous manipulation: Is that in which the aerial system works by itself, in this case, the autonomous approaches are defined as those where the UAVs or propellers perform, in addition to the transport of the whole system, the totality of the task of manipulation  Fig. 1, 2,5 . Assisted manipulation: in this case, the tasks of the UAVs and the tasks of the manipulation system are still a coupled type, but auxiliary engines are incorporated as elements of manipulation or force transmission Fig. 2,6,8 BIB011 . The drones keep the entire structure hovering and the auxiliary engines modify the position of the UAVs or their propellers in a kind of exoskeleton (e.g. by servomotors), this is useful to separate the execution of tasks for which the propellers possibly do not have enough force or torque. So far and according to our investigation, such an operation is characteristic of the conventional mechanisms of steering of coaxial aircrafts and another small UAVs BIB002 , BIB008 , BIB009 ,  BIB007 BIB003 BIB004 BIB006 and the swashplate-systems of bulky and massive aircrafts BIB001 , BIB010 BIB012 BIB005 . Discussion: As was proposed, this section talks about propeller task independence, or certain assistance by using position engines like servomotors, this is a classic deal among force, cargo and dexterity. The purpose of a propeller is to keep an object floating on air, understanding that it will not provide greater lateral forces and moments than thrust of elevation. Therefore, snake aerial manipulators with motorized assistance in the propellers are recommended, notwithstanding the previous line facts, this could be compensated by redirecting the thrust of the propeller through a vectorizer, but since the vectorizer is a auxiliary motorization element the same point is retaken. In this way, at least for the authors, the purpose of an autonomous or non auxiliary motorized snake aerial manipulator is the development of specialized laws of control and the study of phenomena such as turbulence and vortex effects. However, their use should not necessarily applied in force tasks but in mobility and dexterity applications, one of these could be systems able to navigate between windows or pipes without the need for other things than their own propellers. It should be remembered that each auxiliary motor also represents mechanical and electrical load and in both cases the duration of batteries is reduced or the cost for using power tethered supplies is increased. On the other hand, in the case of the methods based on valves and pumps, the assistance of a motor is questionable and in fact an open question is whether a specialized pneumatic or hydraulic motor is more efficient than the action of a valve or not. In other words, the use of auxiliary motors to move the propellers is a necessary ''exoskeleton'' for physical interaction with objects, this allows the designer to assign the elevation, orientation and position task of the snake aerial manipulator to its propellers and the force of action and contact to the auxiliar engines. A very feasible line of research here is that where the auxiliary engines also work as elements of selective damping (i.e. non-passive dampers) or use them as a channel for haptic interaction. It is also convenient to design mixed systems as for example by using clutches  , that allow the designer to choose when the performance is assisted or autonomous and also to design fault tolerant controllers to continue using the snake aerial manipulators if one or more auxiliary engines are damaged, this implies underactuated tasks (manipulation) sharing space but different functionality with overactuated tasks (the mobility of the entire aerial vehicle)