Download or read book Advanced Robust Nonlinear Control Approaches for Quadrotor Unmanned Aerial Vehicle written by Moussa Labbadi and published by Springer Nature. This book was released on 2021-09-14 with total page 263 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book studies selected advanced flight control schemes for an uncertain quadrotor unmanned aerial vehicle (UAV) systems in the presence of constant external disturbances, parametric uncertainties, measurement noise, time-varying external disturbances, and random external disturbances. Furthermore, in all the control techniques proposed in this book, it includes the simulation results with comparison to other nonlinear control schemes recently developed for the tracking control of a quadrotor UAV. The main contributions of the present book for quadrotor UAV systems are as follows: (i) the proposed control methods are based on the high-order sliding mode controller (SMC) and hybrid control algorithm with an optimization method. (ii) the finite-time control schemes are developed by using fast terminal SMC (FTSMC), nonsingular FTSMC (NFTSMC), global time-varying SMC, and adaptive laws. (iii) the fractional-order flight control schemes are developed by using the fractional-order calculus theory, super twisting algorithm, NFTSMC, and the SMC. This book covers the research history and importance of quadrotor system subject to system uncertainties, external wind disturbances, and noise measurements, as well as the research status of advanced flight control methods, adaptive flight control methods, and flight control based on fractional-order theory. The book would be interesting to most academic undergraduate, postgraduates, researchers on flight control for drones and applications of advanced controllers in engineering field. This book presents a must-survey for advanced finite-time control for quadrotor system. Some parts of this book have the potential of becoming the courses for the modelling and control of autonomous flying machines. Readers (academic researcher, undergraduate student, postgraduate student, MBA/executive, and education practitioner) interested in nonlinear control methods find this book an investigation. This book can be used as a good reference for the academic research on the control theory, drones, terminal sliding mode control, and related to this or used in Ph.D. study of control theory and their application in field engineering.

Download or read book Nonlinear and Fault tolerant Control Techniques for a Quadrotor Unmanned Aerial Vehicle written by Tong Li and published by . This book was released on 2011 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: Unmanned Aerial Vehicles (UAVs) have become more and more popular, and how to control them has become crucial. Although there are many different control methods that can be applied to the control of UAVs, nonlinear control techniques are more practical since the nonlinear features of most UAVs. In this thesis, as the first main contribution, three widely used nonlinear control techniques including Feedback Linearization Control (FLC), Sliding Mode Control (SMC), and Backstepping Control (BSC) are discussed, investigated, and designed in details and flight-tested on a unique quadrotor UAV (Qball-X4) test-bed available at the Networked Autonomous Vehicles (NAV) Lab in Concordia University. Each of these three control algorithms has its own features. The advantages and disadvantages are revealed through both simulation and experimental tests. Sliding mode control is well known for its capability of handling uncertainty, and is expected to be a robust controller on Qball-X4 UAV. Feedback linearization control and backstepping control are considered a bit weaker than sliding mode control. A comparison of these three controllers is carried out in both theoretical analysis and experimental results under same fault-free flight conditions. Testing results and comparison show the different features of different control methods, and provide a view on how to choose controller under a specific condition. Besides, safety and reliability of UAVs have been and will always be a critical issue in the aviation industry. Fault-Tolerant Control (FTC) has played an extremely important role towards UAVs' safety and reliability and the safety of group people if an unexpected crash occurred due to faults/damages of UAVs. Therefore, FTC has been a very active and quickly growing research and development field for UAVs and other safety-critical systems. Based on the use of sliding mode control technique, referred to as Fault-Tolerant SMC (FT-SMC) have been investigated, implemented, flight-tested and compared in the Qball-X4 test-bed and also simulation environment in both passive and active framework of FTC in the presence of different actuator faults/damages, as the second main contribution of this thesis work.

Download or read book Dynamic Modeling and Robust Nonlinear Control of Unmanned Quadrotor Vehicle written by Amr Mohamed Elhennawy and published by . This book was released on 2018 with total page 238 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: It is not easy to control a quadrotor due to its highly nonlinear dynamics, variable coupling and model uncertainties. The underactuation property of the quadrotor also poses another degree of complexity to the model due to the limited availability of control techniques that can be applied to underactuated systems. This thesis presents the development of mathematical modeling, control techniques, simulation and real-time testing on a developed quadrotor as an unmanned aerial vehicle. Modeling of the dynamic system of a quadrotor including the motor dynamics is carried out using Newton-Euler mechanics and state space representation is obtained. Using this model a second-order Sliding Mode Control (SMC) is developed as a nonlinear robust control technique. For the SMC development, quadrotor system is divided into two subsystems, One represents the fully actuated degrees of freedom and the other one represents the underactuated degrees of freedom. The aim of the proposed flight controller is to achieve asymptotic position and attitude tracking of the two subsystems by driving the tracking errors to zero to achieve the required tracking performance. Tackling of chattering problem associated with SMC is introduced. Using the developed mathematical model and the developed two control techniques as linear and nonlinear approaches: the Proportional plus Derivative (PD)and SMC, simulation testing is conducted with and without the presence of external disturbances representing weight variation. Multiple simulations testing are performed to ensure the adequacy of the proposed control techniques using MATLAB and Simulink. Detailed discussion on the results of each control technique and comparison are presented with elaborate consideration of the robustness against weight variation. The simulation results demonstrate the ability of the SMC to drive the vehicle to stability and achieve the desired performance characteristics. . Finally, hardware design of a quadrotor has been developed and implemented with considerations on the hardware challenges are presented. Results of real-time ght tests using the two developed control techniques are presented and compared with that of the simulation results and it shows reliable performance of the nonlinear robust SMC controller. Flight tests results came consistent with the simulation results in terms of tracking performance, robustness and actuators e orts. Hardships in the implementation are mentioned and recommendations and future work are proposed.

Download or read book Adaptive Hybrid Control of Quadrotor Drones written by Nihal Dalwadi and published by Springer Nature. This book was released on 2023-03-01 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book discusses the dynamics of a tail-sitter quadrotor and biplane quadrotor-type hybrid unmanned aerial vehicles (UAVs) and, based on it, various nonlinear controllers design like backstepping control (BSC), ITSMC (Integral Terminal Sliding Mode Control), and hybrid controller (BSC + ITSMC). It discusses single and multiple observer-based control strategies to handle external disturbances like wind gusts and estimate states. It covers the dynamics of slung load with a biplane quadrotor and a control architecture to handle the effect of partial rotor failure with wind gusts acting on it. An anti-swing control to prevent damage to the slung load and a deflecting surface-based total rotor failure compensation strategy to prevent damage to the biplane quadrotor are also discussed in this book. The monograph will be helpful for undergraduate and post-graduate students as well as researchers in their advanced studies.

Download or read book Robust Formation Control for Multiple Unmanned Aerial Vehicles written by Hao Liu and published by CRC Press. This book was released on 2022-12-01 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is based on the authors’ recent research results on formation control problems, including time-varying formation, communication delays, fault-tolerant formation for multiple UAV systems with highly nonlinear and coupled, parameter uncertainties, and external disturbances. Differentiating from existing works, this book presents a robust optimal formation approach to designing distributed cooperative control laws for a group of UAVs, based on the linear quadratic regulator control method and the robust compensation theory. The proposed control method is composed of two parts: the nominal part to achieve desired tracking performance and the robust compensation part to restrain the influence of highly nonlinear and strongly coupled parameter uncertainties, and external disturbances on the global closed-loop control system. Furthermore, this book gives proof of their robust properties. The influence of communication delays and actuator fault tolerance can be restrained by the proposed robust formation control protocol, and the formation tracking errors can converge into a neighborhood of the origin bounded by a given constant in a finite time. Moreover, the book provides details about the practical application of the proposed method to design formation control systems for multiple quadrotors and tail-sitters. Additional features include a robust control method that is proposed to address the formation control problem for UAVs and theoretical and experimental research for the cooperative flight of the quadrotor UAV group and the tail-sitter UAV group. Robust Formation Control for Multiple Unmanned Aerial Vehicles is suitable for graduate students, researchers, and engineers in the system and control community, especially those engaged in the areas of robust control, UAV swarming, and multi-agent systems.

Download or read book Robust Discrete Time Flight Control of UAV with External Disturbances written by Shuyi Shao and published by Springer Nature. This book was released on 2020-09-26 with total page 207 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book studies selected discrete-time flight control schemes for fixed-wing unmanned aerial vehicle (UAV) systems in the presence of system uncertainties, external disturbances and input saturation. The main contributions of this book for UAV systems are as follows: (i) the proposed integer-order discrete-time control schemes are based on the designed discrete-time disturbance observers (DTDOs) and the neural network (NN); and (ii) the fractional-order discrete-time control schemes are developed by using the fractional-order calculus theory, the NN and the DTDOs. The book offers readers a good understanding of how to establish discrete-time tracking control schemes for fixed-wing UAV systems subject to system uncertainties, external wind disturbances and input saturation. It represents a valuable reference guide for academic research on uncertain UAV systems, and can also support advanced / Ph.D. studies on control theory and engineering.

Download or read book Lyapunov based Fault Tolerant Control of Quadrotor Unmanned Aerial Vehicles written by Xiaobing Zhang and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Nonlinear Control of Robots and Unmanned Aerial Vehicles written by Ranjan Vepa and published by CRC Press. This book was released on 2016-10-14 with total page 544 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nonlinear Control of Robots and Unmanned Aerial Vehicles: An Integrated Approach presents control and regulation methods that rely upon feedback linearization techniques. Both robot manipulators and UAVs employ operating regimes with large magnitudes of state and control variables, making such an approach vital for their control systems design. Numerous application examples are included to facilitate the art of nonlinear control system design, for both robotic systems and UAVs, in a single unified framework. MATLAB® and Simulink® are integrated to demonstrate the importance of computational methods and systems simulation in this process.

Download or read book Development of Control Algorithm PID LQR for Point to Point Movement of a Nonlinear Quadrotor Unmanned Aerial Vehicle written by Muhammad Kamran binti Joyo and published by . This book was released on 2013 with total page 78 pages. Available in PDF, EPUB and Kindle. Book excerpt: In recent years the area of quadrotor UAV has drawn prominent attention of the researchers enabling to develop immense research area in the field of UAVs. A quadrotor has a simple architectural design due to which designing gets simple. Having advantage of uniqueness in shape and simple design it carries numerous kinds of issues regarding its controlling. A quadrotor system is nonlinear in nature, so it requires a suitable controller to ensure its stability during flight. However, researchers have been able to provide some solutions to the issues regarding angular stability, altitude and position control of quadrotor under the challenging conditions such as wind burst and noisy measurements but still they are not successfully resolved. In this thesis report modern control design techniques are discussed and their application in quadrotor control issues are presented. The control techniques are implemented on a longitudinal motion control of quadrotor i.e. issues related while maneuvering on horizontal plane. After imposing few renowned control techniques on the system it was observed that system requires to build a robust control technique for the quadrotor system. An innovative and more robust control technique is proposed for the position controlling quadrotor system. The controller is designed by fusing two distinct control techniques PID and LQR, which is named as PID-LQR. While flying quadrotor can experience two major issues; noises and external disturbance applied on the system. The nature of noises is the noise generated from GPS sensor and the system itself. The nature of disturbance is the disturbance applied externally on the system. The control technique works in such a way that PID is used for tackling a disturbance such as an external push or wind gust and LQR for rejecting noises of the sensor measurements. Furthermore the effectiveness of proposed control technique is also verified by comparing it with auto-tuned PID and optimized LQR techniques under disturbed and noisy conditions. The simulated results indicate that the proposed method yields a better response as compared to the conventional methods.

Download or read book Flight Formation Control written by Josep M. Guerrero and published by John Wiley & Sons. This book was released on 2012-12-17 with total page 279 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the last decade the development and control of Unmanned Aerial Vehicles (UAVs) has attracted a lot of interest. Both researchers and companies have a growing interest in improving this type of vehicle given their many civilian and military applications. This book presents the state of the art in the area of UAV Flight Formation. The coordination and robust consensus approaches are presented in detail as well as formation flight control strategies which are validated in experimental platforms. It aims at helping students and academics alike to better understand what coordination and flight formation control can make possible. Several novel methods are presented: - controllability and observability of multi-agent systems; - robust consensus; - flight formation control; - stability of formations over noisy networks; which generate solutions of guaranteed performance for UAV Flight Formation. Contents 1. Introduction, J.A. Guerrero. 2. Theoretical Preliminaries, J.A. Guerrero. 3. Multiagent Coordination Strategies, J.A. Guerrero, R. Lozano, M.W. Spong, N. Chopra. 4. Robust Control Design for Multiagent Systems with Parametric Uncertainty, J.A. Guerrero, G. Romero. 5. On Adaptive and Robust Controlled Synchronization of Networked Robotic Systems on Strongly Connected Graphs, Y.-C. Liu, N. Chopra. 6. Modeling and Control of Mini UAV, G. Flores Colunga, J.A. Guerrero, J. Escareño, R. Lozano. 7. Flight Formation Control Strategies for Mini UAVs, J.A. Guerrero. 8. Formation Based on Potential Functions, L. García, A. Dzul. 9. Quadrotor Vision-Based Control, J.E. Gomez-Balderas, J.A. Guerrero, S. SALAZAR, R. Lozano, P. Castillo. 10. Toward Vision-Based Coordination of Quadrotor Platoons, L.R. García Carrillo, J.A. Guerrero, R. Lozano. 11. Optimal Guidance for Rotorcraft Platoon Formation Flying in Wind Fields, J.A. Guerrero, Y. Bestaoui, R. Lozano. 12. Impact of Wireless Medium Access Protocol on the Quadrotor Formation Control, J.A. Guerrero, Y. Challal, P. Castillo. 13. MAC Protocol for Wireless Communications, A. Mendez, M. Panduro, O. Elizarraras, D. Covarrubias. 14. Optimization of a Scannable Pattern for Bidimensional Antenna Arrays to Provide Maximum Performance, A. Reyna, M.A. Panduro, A. Mendez.

Download or read book Advanced Contemporary Control written by Andrzej Bartoszewicz and published by Springer Nature. This book was released on 2020-06-24 with total page 1560 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents the proceedings of the 20th Polish Control Conference. A triennial event that was first held in 1958, the conference successfully combines its long tradition with a modern approach to shed light on problems in control engineering, automation, robotics and a wide range of applications in these disciplines. The book presents new theoretical results concerning the steering of dynamical systems, as well as industrial case studies and worked solutions to real-world problems in contemporary engineering. It particularly focuses on the modelling, identification, analysis and design of automation systems; however, it also addresses the evaluation of their performance, efficiency and reliability. Other topics include fault-tolerant control in robotics, automated manufacturing, mechatronics and industrial systems. Moreover, it discusses data processing and transfer issues, covering a variety of methodologies, including model predictive, robust and adaptive techniques, as well as algebraic and geometric methods, and fractional order calculus approaches. The book also examines essential application areas, such as transportation and autonomous intelligent vehicle systems, robotic arms, mobile manipulators, cyber-physical systems, electric drives and both surface and underwater marine vessels. Lastly, it explores biological and medical applications of the control-theory-inspired methods.

Download or read book Robust Integral Backstepping Control of a Quadrotor Unmanned Aerial Vehicle written by and published by . This book was released on 2014 with total page 184 pages. Available in PDF, EPUB and Kindle. Book excerpt: For the case of quadrotor unmanned aerial vehicle control, a non-linear model and robust integral backstepping control method is proposed to provide stabilization of attitude and motion under different assumptions and environmental uncertainties. The developed control method is robust to reject external disturbances and compensate for potential parameter uncertainties. This thesis investigates the advantages of a robust integral backstepping controller based on the plant model. An analysis of the benefits of the proposed control method is presented by comparison to classic linear control methods. This analysis is supported by simulation of a mathematical model and a physical prototype of the quadrotor system. The parameters and assumptions modeled match that of the constructed prototype to provide a consistent means of validation.

Download or read book Robust and Adaptive Control Methods for Small Aerial Vehicles written by Prasenjit Mukherjee and published by . This book was released on 2012 with total page 86 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent advances in sensor and microcomputer technology and in control and aeroydynamics theories has made small unmanned aerial vehicles a reality. The small size, low cost and manoueverbility of these systems has positioned them to be potential solutions in a large class of applications. However, the small size of these vehicles pose significant challenges. The small sensors used on these systems are much noisier than their larger counterparts. The compact structure of these vehicles also makes them more vulnerable to environmental effects. This work develops several different control strategies for two sUAV platforms and provides the rationale for judging each of the controllers based on a derivation of the dynamics, simulation studies and experimental results where possible. First, the coaxial helicopter platform is considered. This sUAV's dual rotor system (along with its stabilizer bar technology) provides the ideal platform for safe, stable flight in a compact form factor. However, the inherent stability of the vehicle is achieved at the cost of weaker control authority and therefore an inability to achieve aggressive trajectories especially when faced with heavy wind disturbances. Three different linear control strategies are derived for this platform. PID, LQR and H[infin] methods are tested in simulation studies. While the PID method is simple and intuitive, the LQR method is better at handling the decoupling required in the system. However the frequency domain design of the H[infin] control method is better at suppressing disturbances and tracking more aggressive trajectories. The dynamics of the quadrotor are much faster than those of the coaxial helicopter. In the quadrotor, four independent fixed pitch rotors provide the required thrust. Differences between each of the rotors creates moments in the roll, pitch and yaw directions. This system greatly simplifies the mechanical complexity of the UAV, making quadrotors cheaper to maintain and more accessible. The quadrotor dynamics are derived in this work. Due to the lack of any mechanical stabilization system, these quadrotor dynamics are not inherently damped around hover. As such, the focus of the controller development is on using nonlinear techniques. Linear quadratic regulation methods are derived and shown to be inadequate when used in zones moderately outside hover. Within nonlinear methods, feedback linearization techniques are developed for the quadrotor using an inner/outer loop decoupling structure that avoids more complex variants of the feedback linearization methodology. Most nonlinear control methods (including feedback linearization) assume perfect knowledge of vehicle parameters. In this regard, simulation studies show that when this assumption is violated the results of the flight significantly deteriorate for quadrotors flying using the feedback linearization method. With this in mind, an adaptation law is devised around the nonlinear control method that actively modifies the plant parameters in an effort to drive tracking errors to zero. In simple cases with sufficiently rich trajectory requirements the parameters are able to adapt to the correct values (as verified by simulation studies). It can also adapt to changing parameters in flight to ensure that vehicle stability and controller performance is not compromised. However, the direct adaptive control method devised in this work has the added benefit of being able to modify plant parameters to suppress the effects of external disturbances as well. This is clearly shown when wind disturbances are applied to the quadrotor simulations. Finally, the nonlinear quadrotor controllers devised above are tested on a custom built quadrotor and autopilot platform. While the custom quadrotor is able to fly using the standard control methods, the specific controllers devised here are tested on a test bench that constrains the movement of the vehicle. The results of the tests show that the controller is able to sufficiently change the necessary parameter to ensure effective tracking in the presence of unmodelled disturbances and measurement error.

Download or read book Vision Based Autonomous Control Schemes for Quadrotor Unmanned Aerial Vehicle written by Laxmidhar Behera and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This chapter deals with the development of vision-based sliding mode control strategies for a quadrotor system that would enable it to perform autonomous tasks such as take-off, landing and visual inspection of structures. The aim of this work is to provide a basic understanding of the quadrotor dynamical model, key concepts in image processing and a detailed description of the sliding mode control, a widely used robust non-linear control scheme. Extensive MATLAB simulations are presented to enhance the understanding of the controller on the quadrotor system subjected to bounded disturbances and uncertainties. The vision algorithms developed in this chapter would provide the necessary reference trajectory to the controller enabling it to exercise control over the system. This work also describes, in brief, the implementation of the developed control and vision algorithms on the DJI Matrice 100 to present real-time experimental data to the readers of this chapter.

Download or read book Unmanned Aerial Systems written by Anis Koubaa and published by Academic Press. This book was released on 2021-01-21 with total page 652 pages. Available in PDF, EPUB and Kindle. Book excerpt: Unmanned Aerial Systems: Theoretical Foundation and Applications presents some of the latest innovative approaches to drones from the point-of-view of dynamic modeling, system analysis, optimization, control, communications, 3D-mapping, search and rescue, surveillance, farmland and construction monitoring, and more. With the emergence of low-cost UAS, a vast array of research works in academia and products in the industrial sectors have evolved. The book covers the safe operation of UAS, including, but not limited to, fundamental design, mission and path planning, control theory, computer vision, artificial intelligence, applications requirements, and more. This book provides a unique reference of the state-of-the-art research and development of unmanned aerial systems, making it an essential resource for researchers, instructors and practitioners. Covers some of the most innovative approaches to drones Provides the latest state-of-the-art research and development surrounding unmanned aerial systems Presents a comprehensive reference on unmanned aerial systems, with a focus on cutting-edge technologies and recent research trends in the area

Download or read book Trajectory Generation for a Quadrotor Unmanned Aerial Vehicle written by Douglas Conover and published by . This book was released on 2018 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt: The field of multirotor unmanned aerial vehicles (UAVs) has seen substantial progression in the past decade. Trajectory generation and control has been a main focus in this domain, with methods that enable the performance of complex three-dimensional maneuvers through space. Efforts have been made to execute these maneuvers using concepts of nonlinear control and differential flatness. However, a lack of theory for the estimation of higher-order dérivatives of a multirotor UAV has prevented the experimental application of several of these techniques concentrated on trajectory control. This work firstly explores the existing control approach of sequential composition for the execution of quadrotor manoeuvres through narrow windows. This technique involves the combination of several theoretically simple controllers in sequence in order to produce a complex result. Experimental results conducted in the Mobile Robotics and Automated Systems Laboratory (MRASL) at Polytechnique demonstrate the validity of this approach, producing precise and repeatable manoeuvres through narrow windows. However, they also show the limitations of such a method in real world applications, notably its initial inaccuracy and lack of feasibility evaluation. This thesis then focuses on the development of a state-estimation architecture based on linear Kalman filter techniques in order to provide a real-time value of a quadrotor UAV's second and third derivatives (referred to as acceleration and jerk, respectively). Filters of different complexities are developed with the goal of incorporating all available system information into the resulting estimate. A full-state estimator is produced that uses a quadrotor's position and acceleration measurements as well as control inputs in order to be usable for feedback. A jerk-augmented controller based off of optimal control theory is then developed in order to validate this estimator. It is designed in such a way to use the UAV's jerk, acceleration, velocity and position as design parameters and to be unstable without feedback in each of these terms. Tests are conducted in order to examine the performance of both the estimator and controller. Firstly, the quadrotor is commanded to track various reference inputs in 3D space to ensure its stability. The controller tracks these references very closely to simulated responses. The controller is then asked to follow a changing reference in order to evaluate the precision of the developed estimator. Results show that the real-time estimation of the jerk follows offline values adequately. To the best of our knowledge, this is the first application to implement the feedback of a multirotor UAV's jerk in real-world experimentation.

Download or read book Autonomous Flying Robots written by Kenzo Nonami and published by Springer Science & Business Media. This book was released on 2010-09-15 with total page 341 pages. Available in PDF, EPUB and Kindle. Book excerpt: The advance in robotics has boosted the application of autonomous vehicles to perform tedious and risky tasks or to be cost-effective substitutes for their - man counterparts. Based on their working environment, a rough classi cation of the autonomous vehicles would include unmanned aerial vehicles (UAVs), - manned ground vehicles (UGVs), autonomous underwater vehicles (AUVs), and autonomous surface vehicles (ASVs). UAVs, UGVs, AUVs, and ASVs are called UVs (unmanned vehicles) nowadays. In recent decades, the development of - manned autonomous vehicles have been of great interest, and different kinds of autonomous vehicles have been studied and developed all over the world. In part- ular, UAVs have many applications in emergency situations; humans often cannot come close to a dangerous natural disaster such as an earthquake, a ood, an active volcano, or a nuclear disaster. Since the development of the rst UAVs, research efforts have been focused on military applications. Recently, however, demand has arisen for UAVs such as aero-robotsand ying robotsthat can be used in emergency situations and in industrial applications. Among the wide variety of UAVs that have been developed, small-scale HUAVs (helicopter-based UAVs) have the ability to take off and land vertically as well as the ability to cruise in ight, but their most importantcapability is hovering. Hoveringat a point enables us to make more eff- tive observations of a target. Furthermore, small-scale HUAVs offer the advantages of low cost and easy operation.