Snake Aerial Manipulators: A Review <s> C. APPLICATIONS AND DRAWBACKS <s> This paper proposes a control strategy for the stabilization of a jet-powered flying humanoid robot. In particular, the contribution of the paper concerns the design of a control framework capable of tracking a desired robot position and orientation trajectory while flying. Asymptotic stability of the closed loop system is shown by means of a Lyapunov analysis. Simulations are carried out on a model of the humanoid robot iCub to verify the soundness of the proposed approach. <s> BIB001 </s> Snake Aerial Manipulators: A Review <s> C. APPLICATIONS AND DRAWBACKS <s> In this article, a novel Thrust Vectoring Vortex Climbing Robot (TVV-CR) will be presented from a design development and experimental evaluation perspective. To the goal of providing an efficient and robust climbing robot design, with minimized weight and high permissible payload, a novel Electric Ducted Fan (EDF)-based actuation design is proposed for achieving simultaneous locomotion and adhesion via a controllable tilt mechanism, while excluding the need for active motorized wheels. Towards the development of the TVV-CR, the design and development stages will be presented in detail, while proposing a P-PI-based cascaded control structure for evaluating its overall properties. The efficiency of the suggested scheme will be evaluated by multiple experimental results indicating the robot's ability to follow randomly generated paths, while maintaining its adhesion under different surface inclinations. <s> BIB002 </s> Snake Aerial Manipulators: A Review <s> C. APPLICATIONS AND DRAWBACKS <s> This report aims to present maneuverability of an underwater vehicle with a thrust vectoring system. So far, the thrust vectoring system has been applied in the products of Bluefin Robotics, and its equipment makes possible to eliminate the protrude control fins. It is also capable of contributing the better maintenance and handling in actual operation. In this paper, at first, captive model tests and free running model tests in towing tank are extensively conducted for the model having thrust vectoring system, and then used mathematical model of the thrust vectoring inspired by the azimuthing propeller model of the surface ships is correlated. As a result, the tank test results show that although the thrust vectoring system in this research generates larger rudder forces at lower speed range, there exists the directional instability due to the low slenderness and the elimination of the aft control surface. In addition, the numerical consideration using an optimal control theory shows that the additional aft fins on the shroud of thrust vectoring system well contribute directional stability and controllability over a wide speed range. <s> BIB003 </s> Snake Aerial Manipulators: A Review <s> C. APPLICATIONS AND DRAWBACKS <s> The recent advances in state estimation, perception, and navigation algorithms have significantly contributed to the ubiquitous use of quadrotors for inspection, mapping, and aerial imaging. To further increase the versatility of quadrotors, recent works investigated the use of an adaptive morphology, which consists of modifying the shape of the vehicle during flight to suit a specific task or environment. However, these works either increase the complexity of the platform or decrease its controllability. In this letter, we propose a novel, simpler, yet effective morphing design for quadrotors consisting of a frame with four independently rotating arms that fold around the main frame. To guarantee stable flight at all times, we exploit an optimal control strategy that adapts on the fly to the drone morphology. We demonstrate the versatility of the proposed adaptive morphology in different tasks, such as negotiation of narrow gaps, close inspection of vertical surfaces, and object grasping and transportation. The experiments are performed on an actual, fully autonomous quadrotor relying solely on onboard visual-inertial sensors and compute. No external motion tracking systems and computers are used. This is the first work showing stable flight without requiring any symmetry of the morphology. <s> BIB004 </s> Snake Aerial Manipulators: A Review <s> C. APPLICATIONS AND DRAWBACKS <s> This article reviews the current state of the art in the development of modular reconfigurable robot (MRR) systems and suggests promising future research directions. A wide variety of MRR systems h... <s> BIB005 </s> Snake Aerial Manipulators: A Review <s> C. APPLICATIONS AND DRAWBACKS <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> BIB006 </s> Snake Aerial Manipulators: A Review <s> C. APPLICATIONS AND DRAWBACKS <s> Abstract Autonomous underwater vehicles (AUVs), which serve as main tool platforms, have played an important role in underwater surveys in scientific, military, and commercial applications. However, conventional AUVs are unable to perform missions at zero or low forward speeds because the control surfaces are ineffective in this regime. This paper presents novel vectored-thruster AUVs based on a 3-R P S parallel manipulator; the performance of the AUVs at zero and low forward speeds is found to be effectively improved. The 3-R P S parallel manipulator used for the thrust-vectoring mechanism provides certain advantages, including high positioning accuracy, fast response and compact structure. Additionally, studies of the kinematics and dynamics of the thrust-vectoring mechanism have been performed through a theoretical analysis and numerical simulation. Meanwhile, a simplified kinematics method for the 3-R P S parallel manipulator is presented and verified in MATLAB. The analysis and numerical simulation of the thrust-vectoring mechanism prove the feasibility of the design. Using this novel thrust-vectoring mechanism based on the 3-R P S parallel manipulator, the AUVs obtain the ability to provide the motion required for thrust-vectoring propulsion effectively and efficiently. <s> BIB007 </s> Snake Aerial Manipulators: A Review <s> C. APPLICATIONS AND DRAWBACKS <s> The paper contributes towards the modeling, identification, and control of model jet engines. We propose a nonlinear, second order model in order to capture the model jet engines governing dynamics. The model structure is identified by applying sparse identification of nonlinear dynamics, and then the parameters of the model are found via gray-box identification procedures. Once the model has been identified, we approached the control of the model jet engine by designing two control laws. The first is based on the classical Feedback Linearization technique, while the second one on the Sliding Mode control method. The overall methodology has been verified by modeling, identifying and controlling two model jet engines, i.e. P100-RX and P220-RXi developed by JetCat, which provide a maximum thrust of 100 N and 220 N, respectively. <s> BIB008 </s> Snake Aerial Manipulators: A Review <s> C. APPLICATIONS AND DRAWBACKS <s> ABSTRACTThe traditional way to underwater thrust vectoring is mainly based on a specially designed mechanical system which provides the propulsion system additional degree of freedom. This method i... <s> BIB009
With the existing technology their immediate application is not entirely feasible due to power consumption and omnidirectionality challenges even with tethered power supplies (tethered in the sense of power because concerning to this topic is also employed in the sense of linkage). However, they allow the study and research on derived applications such as the reconfigurable robotics BIB004 ,  , BIB005 Fig.2 , the continuum robotics BIB006 , flying humanoids and non-flying vehicles. In the first case, they are modular shape-morphing structures moving through the three-dimensional space. In the second case, snake aerial manipulators can be seen as discrete systems powered by the action of propellers and thus, they lay the preliminary notions for the study of continuous systems driven through valves and pneumatic or hydraulic fluids, leaving in this case the open problem on the efficiency between using actuators based on the motor-propeller interaction or those based on valves and flows. Concerning to flying humanoids, snake aerial manipulators can be seen as the subsystems or limbs of this kind of robots BIB001  BIB008 . Finally, with respect to non-flying vehicles it must be indicated that extrapolations of the topics described in this text to vehicles different from aircraft can be found at BIB009 BIB002 BIB007 BIB003  . More details about the aforementioned drawbacks and other important problems will be analysed in the next sections.