Posted on

Controller Design Of Twin Rotor System Engineering Essay

The inquiry of Multi-Input-Multi-Output ( MIMO ) control has ever been a thought- provoking sub-field surrounded by the field of control technology. Among the systems that involve MIMO control, the chopper rises out as one of the dramatic theoretical accounts. This sort of aircraft demands two rotors, whirling in perpendicular planes, hence, can non depend on Single-Input-Single-Output accountants to maneuver in the deep infinite. Besides, un-manned choppers have non yet been viewed in ground forcess globally ; this fact gives the occupation of planing MIMO control systems for choppers a big infinite to excite [ 1 ] .

The twin rotor system establishes the conventions of a nonlinear MIMO system with considerable cross yoke. Its operation approaches a chopper but the angle of onslaught of the rotors is fixed, and the aerodynamic forces are regulated by altering the velocity of motors. The full mechanical theoretical account for this machine has been matured. Based on this mechanical theoretical account, assorted control designs are devised to command the setup utilizing MATLAB-Simulink [ 2 ] . These control schemes are formed to fix the Twin-Rotor system go to prearranged aims and trail periodic input signals.

The exercising of intriguing the control designs demands the writer to make much labour on state-space formation linearization and exploratory plants. Mathematical appraisal is besides executed to accomplish the approximated multinomials for variables association. In most of the realistic control systems such as flight control systems, there survives impregnation limitation on accountant end products [ 3 ] , [ 4 ] . If a feedback accountant intended without taking into consideration such restraint is employed the closed-loop system may be inconsistent in the instance where big external signal is supplemented. One method to handle with such a trouble is to explicate a low-gain accountant which does non shock input restrictions for all extrinsic signals that will be introduced. However, it is clear that this attack culminates in fusty control operation.

The TRS comprises of a beam centered on its nucleus in such a manner that it can spiral freely both in the horizontal and perpendicular planes. At both terminals of the beam, there are rotors ( chief rotor and tail rotor ) steered by DC motors. A counterweight arm with a weight on its terminal is rooted to the beam at the axis [ 5 ] . The province of the beam is characterized by four system variables: horizontal and perpendicular angles calculated by place detectors provided at the pivot, and two matching angular speeds. Two conventional province variables are the angular speeds of the rotors, regulated by tachometers linked with the DC motors [ 6 ] .

In a standard chopper, the aerodynamic force is regulated by changing the angle of onslaught. However, where the angle of onslaught is fixed so the aerodynamic force is controlled by changing the velocity of motors. Therefore, the control inputs are supply electromotive forces of the DC motors. A alteration in the electromotive force usage ends in a alteration of the whirling velocity the rotor which culminates in a alteration of the complementary place of the beam.

To get the better of the conservative design attack, different control approaches that employ online optimisation have been introduced [ 7 ] , [ 8 ] , [ 9 ] . The state-dependent gain-scheduled control strategy [ 8 ] , [ 9 ] is one of the attacks. In this design a control regulation which has an agreement that a high-gain control regulation and a low addition control regulation are interposed by a programming parametric quantity is employed. The programming parametric quantity is settled by calculating out a bulging optimisation inquiry on-line. The control jurisprudence of [ 8 ] , [ 9 ] is formed established on the polytypic account of a impregnation portion of [ 10 ] . As a effect, the control jurisprudence can achieve great subdivision of appeal even if the works is unstable. This process is expanded to tracking control jobs [ 11 ] . However, efficiency of these attacks are assessed merely by manner of numerical paradigms of additive systems whose sizes are illumination and have non been entrenched by experiments. In existent systems, there exist interventions, nonlinearities, unmodeled kineticss, and computational hold. These constituents may hold badly detrimental furnishings on control public presentation. Therefore, to gauge the competency of the methods of [ 8 ] , [ 9 ] , [ 11 ] by experiments is rather of import to set the methods to practical usage.

Fig.1 Model of TRS

The theoretical account of TRS is given in Fig.1. It comprises of a perpendicular axis A on which a lever arm L is connected by a cylindrical articulation utilizing an L shaped nexus. This L shaped nexus is made of two bars: one saloon holding a length h1 and the other holding a length h2. These two bars are at right angles to each other. The saloon h1 works as the horizontal axis. Two rotors are scaled on the lever arm: a chief rotor and a tail rotor. The electromotive forces u1 and u2 are the inputs to this theoretical account. A weight is mounted on an adjustable place towards the tail rotor.


In this subdivision the linearized province infinite theoretical account of TRS is given. Nonlinear theoretical account of TRS is foremost linearized about its operating point. The operating point that we found work outing the nonlinear province infinite equations of TRS is given below

This operating point is found utilizing the MATLAB bid “ spare ” . Using this operating point in MATLAB we found the linearized theoretical account of TRS utilizing the bid “ linmod. ” The additive theoretical account is given below.

( 1 )

( 2 )


= AZ angle

= AZ speed

= lift angle

= lift speed

= angular speed of chief rotor

= angular speed of tail rotor

= triping signal

= triping signal

= AZ angle

= lift angle

This province infinite theoretical account will be used in following subdivisions to plan the different type of accountants for twin rotor system.


In this subdivision we will be planing the and accountants for twin rotor system. Before planing the optimum accountants we check the system response by planing a Linear Quadratic Regulator ( LQR ) utilizing the MATLAB bid “ K=lqr ( A, B, Q, R, N ) . ” The matrices Q and R are chosen by hit and test method and it must be noted that the Q matrix must be semi positive definite and R matrix must be symmetric positive definite. The accountant addition K that we got from LQR is given below.

The responses of the system with measure input utilizing this accountant are given Fig.2.

Fig.2 Step Response with LQR

Linear simulation consequences are shown in Fig.3.

Fig.3 Linear Simulation Results of LQR

It is apparent from the simulation consequences that the accountant designed by LQR in MATLAB does non supply sufficient stableness to the TRS system. As this does non supply the coveted consequences so we move towards the design of and accountants.

First we design the accountant for TRS. We know that this type of accountant minimizes the cost map of the system while supplying the supportive consequences. To plan this accountant we use the MATLAB bid “ [ K.Tzw ] =h2syn ( P.Ny, Nu ) ” that gives us the accountant addition K for our works i.e TRS system. Here P is the jammed works of our additive theoretical account, Ny is the dimension of end product at Nu is the dimension of input. This accountant is obtained after work outing the Riccati equation. The accountant obtained through this is given in the matrix below.

After acquiring this accountant addition K we made a simulink theoretical account and run the simulations after puting the parametric quantities harmonizing to our demand. The simulink theoretical account and its responses are given in Fig.4 and Fig.5.


Fig.4 Simulink theoretical account for H2 Control

The end product Y is obtained utilizing range 3, response of works is obtained utilizing range 2 and response of accountant is obtained utilizing range 1 in simulink theoretical account. . Perturbations are besides added in simulink theoretical account.


Fig.5 Simulation of Simulink theoretical account with perturbations

Simulation consequences show that the accountant designed utilizing H2 attack is robust and it stabilizes the works in the presence of uncertainnesss. In comparing with LQR, H2 is much more robust and gives the coveted consequence for TRS.

Now we design the accountant like H2 accountant. To plan this type of accountant we use MATLAB bid

[ K, Tzw, Gama ] =hinfsyn ( P, Ny, Nu, Gamamin, Gamamax, Tol, )

In this bid P is the jammed works matrix, Ny and Nu are the dimensions of end product and input, Gamamin and Gama soap are the minimal and maximal bounds of gama and tol is the tolerance parametric quantity. The accountant obtained through this is

After acquiring this accountant addition K we made a simulink theoretical account and run the simulations after puting the parametric quantities harmonizing to our demand. The simulink theoretical account and its responses are given in Fig.6 and Fig.7.


Fig.6 Simulink theoretical account for accountant

The responses are given below.


Fig.7 Responses of accountant

Simulation consequences show that the accountant designed utilizing attack is robust and it stabilizes the works in the presence of uncertainnesss. In comparing with LQR, is much more robust and gives the coveted consequence for TRS.

Simulation Parameters

This subdivision gives the parametric quantities that are used in simulations to obtain the additive province infinite theoretical account of duplicate rotor system.




Unit of measurement

Arm length to chief rotor




Arm length to chase rotor




Mass of lever saloon




Horizontal distance




Vertical distance




Distance from pivot to burden




Mass of weight




Mass of chief rotor




Mass of tail rotor




Time changeless for chief rotor




Time changeless for tail rotor




Lift coefficient for chief rotor




Drag coefficient for chief rotor




Lift coefficient for tail rotor




Drag coefficient for tail rotor




Motor invariable for chief rotor




Motor invariable for tail rotor




Clash of perpendicular axle bearing




Clash of horizontal axle bearing





In this paper we have expeditiously designed and Controllers for a twin rotor system. Simulation consequences shown in this paper are the grounds that the accountants that are designed in MATLAB are robust plenty that it can manage the works with more efficiency when there are some perturbations are besides present. In comparing with LQR, both the accountants provide stabilising consequences and guarantee that the works will stay stable. Sufficient back uping graphs are shown in this paper that support the accomplishment of the said nonsubjective. Although the system in originally unstable and nonlinear but after linearization it can be made stable utilizing the processs of accountant designs.

Leave a Reply

Your email address will not be published.