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Helicopters performing external load missions are subject to instabilities that arise in high speed flight that limit their operational flight envelope. This thesis addresses the problem of active stabilization of slung loads in high speed flight. To demonstrate the method, simulations of a utility helicopter with a dynamic inversion controller (as its automatic flight control system) and a CONEX cargo container were used. An airspeed scheduled controller utilizing cable angle feedback to the primary dynamic inversion controller was designed for the nonlinear coupled system by the classic root locus technique. Nonlinear simulations of straight and level flight at different airspeeds were used to validate the controller performance in stabilizing the load pendulum motions. Controller performance was also evaluated in a complex maneuver and in more demanding scenarios by adding different levels of atmospheric turbulence to the previous cases. The results show that the use of cable angle feedback provides or improves system stability when turbulence is not included in the simulation. When light/moderate turbulence is present sustained limit cycle oscillations are avoided by the use of the controller. For severe turbulence levels, the controller did not provide any significant improvement.
Helicopters must carry out a variety of missions, ranging from military to civilian uses. Missions mayinvolve delivery of a payload from one location to another. Some loads are externally attached to thehelicopter by cables. In this configuration, the loads are referred to as slung loads. Due to the couplingbetween the slung load aerodynamics and inertial forces, loads dynamics can become unstable whenairspeed increases. Slung load instabilities limit the flight operations of a rotorcraft. Because limitingflight speeds reduce the operational efficiency of the rotorcraft, methods for stabilizing external loadsin forward flight are the subject for research. In recent years, the dynamics and control of slung loadswere studied using analysis, dynamic wind tunnel tests, and flight tests.The research presented in this thesis investigated a control design methodology and its feasibilityto stabilize an external load across the flight envelope, including high speed flight. The capability of anactive cargo hook (ACH) to provide external load stabilization in high speed flight is studied. The ACHis an electromechanical device that can slide longitudinally and laterally along the base of the fuselage.Previous work used the ACH to directly control the loads roll and pitch but only during hover and lowspeed flight. Previous studies results proved promising.The test load and helicopter simulated in this thesis is a CONEX cargo container and a UH-60 BlackHawk helicopter, respectively. During high speed flight, the load can become unstable, exhibiting sustainedperiodic motion, or limit cycle oscillations, which can degrade helicopter handling qualities. Previousstudies observed the load dynamics in a wind tunnel. The findings showed the excessive swingingand rotation in the slung load are due to its nonlinear dynamics.The control methodology first examined designed a full-state feedback (FSF) linear-quadratic regulator(LQR) controller. In this controller, the load states and cargo hook longitudinal and lateral positionsare used as inputs to the controller with the commanded cargo hook longitudinal and lateral positionsas outputs. Results showed high damping in the loads attitude response with little saturation in theACH stroke and stroke rate. The full-state LQR controller demonstrated success in stabilizing the slungload.The FSF controller, however, requires sensors to measure the loads states real-time. A more practicalapproach is using a reduced order model (ROM) using relative cable angle feedback (RCAF). With RCAF,the relative cable angles can be measured real-time, requiring less sensors and measurements. Thereduced order model is used to design an LQR controller for the ACH. The inputs for the controllerare the relative cable angles, relative cable angular rates, and ACH positions. The results demonstratedbetter performance than the FSF LQR controller, stabilizing the load approximately 20 percent quicker.The loads damping of the RCAF controller is higher than the FSFs and the ACH does not saturate instroke or stroke rate. The settling time of the load was also improved significantly. Furthermore, thecontrollers robustness was tested through applying a Dryden Turbulence model in the simulations. TheRCAF was able to appropriately stabilize the load through low, mild, and severe turbulence levels.
Backstepping Control of Nonlinear Dynamical Systems addresses both the fundamentals of backstepping control and advances in the field. The latest techniques explored include ‘active backstepping control’, ‘adaptive backstepping control’, ‘fuzzy backstepping control’ and ‘adaptive fuzzy backstepping control’. The reference book provides numerous simulations using MATLAB and circuit design. These illustrate the main results of theory and applications of backstepping control of nonlinear control systems. Backstepping control encompasses varied aspects of mechanical engineering and has many different applications within the field. For example, the book covers aspects related to robot manipulators, aircraft flight control systems, power systems, mechanical systems, biological systems and chaotic systems. This multifaceted view of subject areas means that this useful reference resource will be ideal for a large cross section of the mechanical engineering community. Details the real-world applications of backstepping control Gives an up-to-date insight into the theory, uses and application of backstepping control Bridges the gaps for different fields of engineering, including mechanical engineering, aeronautical engineering, electrical engineering, communications engineering, robotics and biomedical instrumentation
Multiservice Helicopter Sling Load: Basic Operations And Equipment COMDTINST M13482.2B; TM 4-48.09 (FM 4-20.197); MCRP 4-11.3E; NTTP 3-04.11; AFMAN 11-223 On the Cover: K9 Piper is one of the very special dogs that keep airports safe. You can find Piper's social media accounts by searching: @airportsk9. This manual is one of a series of manuals for aviation and ground personnel who perform helicopter sling load missions ashore or aboard ship. These manuals are a coordinated effort of the US Army, US Marine Corps, US Navy, US Air Force, and US Coast Guard. All services participate in the sling load certification program begun by the Army in 1984. These manuals include standardized rigging procedures and other information from that program. Efforts were made to standardize ground crew and hookup procedures and terminology. The terms "helicopter" and "aircraft" refer to vertical lift aircraft that participate in sling load operations. Where service-unique requirements apply to an entire chapter or body of text, the service initials are at the beginning of the chapter or text. Otherwise the initials are at the end of the applicable sentence. The information in this manual will familiarize personnel with the sling sets, cargo nets, and other sling load equipment in the DOD inventory. It will also acquaint them with the helicopters used for sling load and provide basic procedures for rigging and hooking up loads. Rigging equipment and procedures described in this manual may not be authorized for all aircraft or services because of equipment or service restrictions. This manual does not provide details on aviation operations nor does it present detailed data that is normally contained in unit standing operating procedures (SOPs). Why buy a book you can download for free? We print the paperback book so you don't have to. First you gotta find a good clean (legible) copy and make sure it's the latest version (not always easy). Some documents found on the web are missing some pages or the image quality is so poor, they are difficult to read. If you find a good copy, you could print it using a network printer you share with 100 other people (typically its either out of paper or toner). If it's just a 10-page document, no problem, but if it's 250-pages, you will need to punch 3 holes in all those pages and put it in a 3-ring binder. Takes at least an hour. It's much more cost-effective to just order the bound paperback from Amazon.com This book includes original commentary which is copyright material. Note that government documents are in the public domain. We print these paperbacks as a service so you don't have to. The books are compact, tightly-bound paperback, full-size (8 1/2 by 11 inches), with large text and glossy covers. 4th Watch Publishing Co. is a HUBZONE SDVOSB. https: //usgovpub.com
This second of three volumes from the inaugural NODYCON, held at the University of Rome, in February of 2019, presents papers devoted to Nonlinear Dynamics and Control. The collection features both well-established streams of research as well as novel areas and emerging fields of investigation. Topics in Volume II include influence of nonlinearities on vibration control systems; passive, semi-active, active control of structures and systems; synchronization; robotics and human-machine interaction; network dynamics control (multi-agent systems, leader-follower dynamics, swarm dynamics, biological networks dynamics); and fractional-order control.