Evaluating H∞ controllers on the NRC Bell 205 fly-by-wire helicopter

Smerlas, Alex; Walker, Daniel J.; Postlethwaite, Ian; Strange, M. E.; Howitt, J.; Gubbels, Arthur

doi:10.1016/s0967-0661(00)00088-5

Cited by 33 publications

(12 citation statements)

References 5 publications

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“…The first helicopter flight-test of an H ∞ controller was conducted in 1997 by the Control Group of the University of Leicester, UK, [26], [25], [22] with subsequent flight tests reported in [29]. More recently, the application of loop-shaping procedures to a new non-linear model of the Bell 205 has led to several improvements [27], [21].…”

Section: Introductionmentioning

confidence: 99%

Static H/sub /spl infin// loop shaping control of a fly-by-wire helicopter

Prempain

Postlethwaite²

2004

2004 43rd IEEE Conference on Decision and Control (CDC) (IEEE Cat. No.04CH37601)

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This paper introduces a novel static output feedback version of the design procedure of McFarlane and Glover [18]. Existence conditions for a static output loop shaping controller are given in terms of two coupled matrix inequalities. Simple linear sufficient conditions can be derived from these coupled nonlinear inequalities and the determination of a static, sub-optimal, H ∞ loop shaping controller reduces to an optimization problem over Linear Matrix Inequalities. The new procedure is demonstrated by its application to the design of a flight control system for the Canadian fly-by-wire research Bell 205 helicopter. The resulting H ∞ controller has just 3 states and would appear to be the simplest flight control system used on this helicopter. The system was successfully flight-tested and high levels of performance were achieved.

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Section: Introductionmentioning

confidence: 99%

Static H/sub /spl infin// loop shaping control of a fly-by-wire helicopter

Prempain

Postlethwaite²

2004

2004 43rd IEEE Conference on Decision and Control (CDC) (IEEE Cat. No.04CH37601)

Self Cite

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“…Conditions for a static output loop-shaping controller in terms of two coupled-matrix inequalities are presented in [22]. The application of loopshaping procedures has lead to several improvements in helicopter control system design methods [23].…”

mentioning

confidence: 99%

Structured H-Infinity Command and Control-Loop Design for Unmanned Helicopters

Gadewadikar

Lewis

Subbarao

et al. 2008

Journal of Guidance, Control, and Dynamics

124

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The aim of this paper is to present rigorous and efficient methods for designing flight controllers for unmanned helicopters that have guaranteed performance, intuitive appeal for the flight control engineer, and prescribed multivariable loop structures. Helicopter dynamics do not decouple as they do for the fixed-wing aircraft case, and so the design of helicopter flight controllers with a desirable and intuitive structure is not straightforward. We use an H 1 output-feedback design procedure that is simplified in the sense that rigorous controller designs are obtained by solving only two coupled-matrix design equations. An efficient algorithm is given for solving these that does not require initial stabilizing gains. An output-feedback approach is given that allows one to selectively close prescribed multivariable feedback loops using a reduced set of the states at each step. At each step, shaping filters may be added that improve performance and yield guaranteed robustness and speed of response. The net result yields an H 1 design with a control structure that has been historically accepted in the flight control community. As an example, a design for stationkeeping and hover of an unmanned helicopter is presented. The result is a stationkeeping hover controller with robust performance in the presence of disturbances (including wind gusts), excellent decoupling, and good speed of response. Nomenclature A = system or plant matrix a s = longitudinal blade angle B = control-input matrix b s = lateral blade angle C = output or measurement matrix D = disturbance matrix D in = inner-loop disturbance matrix D o = outer-loop disturbance matrix dt = disturbance G = nominal plant G s = loop-shaped plant K = static output-feedback gain matrix p = roll rate in the body-frame components Q = state weighting matrix q = pitch rate in the body-frame components R = control weighting matrix r = yaw rate in the body-frame components r fb = yaw-rate feedback U = velocity along the body-frame x axis ut = control input V = velocity along the body-frame y axis W = velocity along the body-frame z axis X = inertial position x axis x in t = inner-loop state vector x o t = outer-loop state vector Y = inertial position y axis y in t = inner-loop output vector y o t = outer-loop output vector Z = inertial position z axis zt = performance output = system L 2 gain in = L 2 gain inner loop o = L 2 gain outer loop = pitch angle = roll angle = yaw angle

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“…The resulting controller has been shown to enjoy some favourable properties, such as no pole-zero cancellation occurs in the closed-loop system (except for a certain special class of plants), see [13]. In addition, the controllers, thus, designed have been successful in various applications; examples are those described in [14][15][16][17].…”

Section: ∞ Loop-shaping Designmentioning

confidence: 99%

Lateral Control Implementation for an Unmanned Aerial Vehicle

Samar

Shah

Nzar³

2013

ISRN Aerospace Engineering

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This paper presents practical aspects of guidance and control design for UAV and its flight test results. The paper focuses on the lateral-directional control and guidance aspects. An introduction to the mission and guidance problem is given first. Waypoints for straight and turning flight paths are defined. Computation of various flight path parameters is discussed, including formulae for real-time calculation of down-range (distance travelled along the desired track), cross-track deviation, and heading error of the vehicle; these are then used in the lateral guidance algorithm. The same section also describes how to make various mission-related decisions online during flight, such as when to start turning and when a waypoint is achieved. The lateral guidance law is then presented, followed by the design of a robust multivariable ∞ controller for roll control and stability augmentation. The controller uses the ailerons and rudder for control of roll angle and stabilization of yaw rate of the vehicle. The reference roll angle is generated by the nonlinear guidance law. The sensors available on-board the vehicle do not measure yaw rate; hence, a practical method of its estimation is proposed. The entire guidance and control scheme is implemented on the flight control computer of the actual aerial vehicle and taken to flight. Flight test results for different mission profiles are presented and discussed.

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Evaluating H∞ controllers on the NRC Bell 205 fly-by-wire helicopter

Cited by 33 publications

References 5 publications

Static H/sub /spl infin// loop shaping control of a fly-by-wire helicopter

Static H/sub /spl infin// loop shaping control of a fly-by-wire helicopter

Structured H-Infinity Command and Control-Loop Design for Unmanned Helicopters

Lateral Control Implementation for an Unmanned Aerial Vehicle

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