Helicopter load alleviation using active control

2008 ◽  
Vol 112 (1137) ◽  
pp. 663-672
Author(s):  
M. Voskuijl ◽  
D. J. Walker ◽  
B. J. Manimala
Keyword(s):  
Control System ◽  
Flight Control ◽  
High Speed ◽  
Flight Control System ◽  
Order Model ◽  
Longitudinal Control ◽  
Handling Qualities ◽  
Control Techniques ◽  
Maneuvering Flight

Abstract This paper discusses how structural load objectives can be included in a rotorcraft flight control system design in an efficient and straightforward way using multivariable control techniques. Several research studies have indicated that pitch link loads for various rotorcraft types can reach high or even unacceptable values, both in steady state and maneuvering flight. This is especially the case for high-speed aggressive maneouvers. Pitch link loads at high-speed flight are therefore taken as a case study. A novel longitudinal control system is presented, designed to reduce helicopter pitch-link loads during high-speed longitudinal manoeuvres whilst providing a pitch attitude command attitude hold response type. The design is based on a high-order model of a helicopter representative of the UH-60 Black Hawk. New metrics are presented for the analysis of structural loads that can be used in combination with ADS-33 handling qualities requirements.

Design and Flight Test of a Cable Angle Feedback Flight Control System for the RASCAL JUH-60 Helicopter

2014 ◽  
Vol 59 (4) ◽  
pp. 1-15 ◽  
Author(s):  
Christina M. Ivler ◽  
J. David Powell ◽  
Mark B. Tischler ◽  
Jay W. Fletcher ◽  
Carl Ott
Keyword(s):  
Control System ◽  
Flight Control ◽  
Flight Test ◽  
Feedback System ◽  
Military Operations ◽  
Flight Control System ◽  
Handling Qualities ◽  
Maneuvering Flight ◽  
Rate Feedback ◽  
Tailored Approach

The ability of a helicopter to carry externally slung loads makes it very versatile for many civil and military operations. However, the piloted handling qualities of the helicopter are degraded by the presence of the slung load. A control system is developed that uses measurements of the slung load motions as well as conventional fuselage feedback to improve the handling qualities for hover/low-speed operations. Prior research has shown a fundamental trade-off between load damping and piloted handling qualities for a feedback control system with cable angle/rate feedback. A new task-tailored approach proposed and implemented herein uses a method of switching between a load damping mode and a piloted handling qualities mode. These modes provide appropriate load feedback depending on the piloting task and flight regime. This provides improved handling qualities for maneuvering flight and for improved precision load control at hover. A new mission task element for precision load placement is developed (for possible inclusion into ADS-33E-PRF) to test the ability of the cable feedback system to improve load placement task performance. The improvements provided by this control system are demonstrated in a piloted flight test on the JUH-60A RASCAL fly-by-wire helicopter. The average load set-down time was reduced by a factor of two for the 1000-lb load on a 56-ft sling.

Design of sliding mode flight control system for a flexible aircraft

2021 ◽  
pp. 095441002110455
Author(s):  
Majeed Mohamed ◽  
Madhavan Gopakumar
Keyword(s):  
Control System ◽  
Rigid Body ◽  
Flight Control ◽  
High Speed ◽  
Sliding Mode ◽  
Flight Mechanics ◽  
Frequency Separation ◽  
Flight Control System ◽  
Flexible Aircraft ◽  
Aircraft Dynamics

The evolution of large transport aircraft is characterized by longer fuselages and larger wingspans, while efforts to decrease the structural weight reduce the structural stiffness. Both effects lead to more flexible aircraft structures with significant aeroelastic coupling between flight mechanics and structural dynamics, especially at high speed, high altitude cruise. The lesser frequency separation between rigid body and flexible modes of flexible aircraft results in a stronger interaction between the flight control system and its structural modes, with higher flexibility effects on aircraft dynamics. Therefore, the design of a flight control law based on the assumption that the aircraft dynamics are rigid is no longer valid for the flexible aircraft. This paper focuses on the design of a flight control system for flexible aircraft described in terms of a rigid body mode and four flexible body modes and whose parameters are assumed to be varying. In this paper, a conditional integral based sliding mode control (SMC) is used for robust tracking control of the pitch angle of the flexible aircraft. The performance of the proposed nonlinear flight control system has been shown through the numerical simulations of the flexible aircraft. Good transient and steady-state performance of a control system are also ensured without suffering from the drawback of control chattering in SMC.

scholarly journals Model-Based Systems Engineering Approach with SysML for an Automatic Flight Control System

2021 ◽  
Author(s):  
Haluk Altay ◽  
M. Furkan Solmazgül
Keyword(s):  
Control System ◽  
Complex Systems ◽  
Systems Engineering ◽  
Flight Control ◽  
Flight Control System ◽  
Engineering Approach ◽  
Model Based ◽  
Multidisciplinary Study ◽  
Model Based Systems Engineering

Systems engineering is the most important branch of engineering in interdisciplinary study. Successfully performing a multidisciplinary complex system is one of the most challenging tasks of systems engineering. Multidisciplinary study brings problems such as defining complex systems, ensuring communication between stakeholders, and common language among different design teams. In solving such problems, traditional systems engineering approach cannot provide an efficient solution. In this paper, a model-based systems engineering approach is applied with a case study and the approach is found to be more efficient. In the case study, the design of the helicopter automatic flight control system was realized by applying model-based design processes with integration of tools. Requirement management, system architecture management and model-based systems engineering processes are explained and applied of the case study. Finally, model-based systems engineering approach is proven to be effective compared with the traditional systems engineering methods for complex systems in aviation and defence industries.

scholarly journals Sliding Mode Implementation of an Attitude Command Flight Control System for a Helicopter in Hover

10.14311/748 ◽  
2005 ◽  
Vol 45 (4) ◽  
Author(s):  
D. J. McGeoch ◽  
E. W. McGookin ◽  
S. S. Houston
Keyword(s):  
Control System ◽  
Flight Control ◽  
Sliding Mode ◽  
Flight Control System ◽  
Design Standards ◽  
Handling Qualities ◽  
Control Scheme ◽  
Non Linear ◽  
Order Representation ◽  
Control Implementation

This paper presents an investigation into the design of a flight control system, using a decoupled non-linear sliding mode control structure, designed using a linearised, 9th order representation of the dynamics of a PUMA helicopter in hover. The controllers are then tested upon a higher order, non-linear helicopter model, called RASCAL. This design approach is used for attitude command flight control implementation and the control performance is assessed in the terms of handling qualities through the Aeronautical Design Standards for Rotorcraft (ADS-33). In this context a linearised approximation of the helicopter system is used to design an SMC control scheme. These controllers have been found to yield a system that satisfies the Level 1 handling qualities set out by ADS-33. 

Flight Simulator as a Tool for Flight Control System Synthesis and Handling Qualities Research

2009 ◽  
Vol 147-149 ◽  
pp. 231-236 ◽  
Author(s):  
Tomasz Rogalski ◽  
Andrzej Tomczyk ◽  
Grzegorz Kopecki
Keyword(s):  
Control System ◽  
Control Systems ◽  
Flight Control ◽  
Flight Simulator ◽  
Flight Control System ◽  
Aircraft Control ◽  
Flight Testing ◽  
Flight Tests ◽  
Control Laws ◽  
Handling Qualities

At the Department of Avionics and Control Systems problems of aeronautical control systems have been dealt with for years. Several different kinds of aeronautical control systems have been designed, prototyped and tested. These control systems are intended for general aviation aircraft and unmanned aircraft. During all research projects computer simulations and laboratory tests were made. However, since in some cases such tests were insufficient, in-flight tests were conducted leading to a series of reliable results. The in-flight tests were made with the use of M-20 Mewa aircraft (autopilot for a GA aircraft) and PZL-110 Koliber aircraft (control system for UAV and indirect flight control system for a GA aircraft). Nevertheless, in-flight testing is very expensive and problematic. To avoid some problems appearing during in-flight tests and their preparation, a simulator – which is normally used for professional pilot training – can be used. The Aviation Training Center of the Rzeszów University of Technology possesses the ALSIM AL-200 MCC flight simulator. We have started preparing this simulator for the research. It is possible to control the simulated aircraft with the use of an external control system. The solution proposed enables testing the aircraft control algorithms, indirect control laws (e.g. control laws modifying handling qualities), as well as testing and assessment of the students’ pilotage skills. Moreover, the solution makes it possible to conduct tests connected with aircraft control, crew management, crew cooperation and flight safety. The simulator allows us to test dangerous situations, which – because of safety reasons – is impossible during in-flight testing. This paper presents modifications to the simulator’s hardware and additional software, which enable the described research.

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