DECOUPLING OF TWIN ROTOR MIMO SYSTEM

By- Murari Lal Garg Vishnuram Abhinav Rahul Nemiwal Kangkana Medhi

Under the guidance of Dr. Jeevamma Jacob

PHASE - 1

TRMS• It is a laboratory set-up designed for control experiments. In certain aspects its behaviour resembles that of a

twin-rotor helicopter.• TRMS is driven by two D.C. motors• Its two propellers are perpendicular to each other and joined by

a beam pivoted on its base that can rotate freely in horizontal and vertical planes

• Joined beam can be moved by changing the input• Voltage in order to control rotational speed of propellers• It is equipped with a pendulum counterweight hanging from

the beam• It possesses a strong coupling between main and tail rotor• So in certain aspect, it resembles of a twin-rotor helicopter

Mathematical Modeling • The system is modelled in terms of 2 DOF

dynamics using Newtonian mechanics.• All the effective forces have to be considered.• Modelling is classified as 2 part:1. 1DOF (without coupling)–I. Vertical part(main rotor)II. Horizontal part(tail rotor)2. 2DOF –

combination of both part with cross coupling

VERTICAL PART(1DOF)• MAIN ROTOR : using Newton torque equation –

And,

Also,

Thus, SIMULINK MODEL –

HORIZONTAL PART (1DOF)• TAIL ROTOR:

same as equations in main rotor –

Thus, SIMULINK MODEL –

• Motor transfer function and torque function of speed of rotor.

Tail rotor-

Main rotor-

Simulation and Results (1DOF)

Response of tail rotor

Response of main rotor

COMPLETE 2DOF MODEL

RESULTS

Response of the system with unit step input to main rotor and unit impulse to tail rotor

Response of tail rotor to various inputs with different main rotor input

Response of main rotor to different step input

CONCLUSION• Output of system is obtained what is

expected.• Settling time of main rotor is very high.• Response of input to main rotor is highly non-

linear.• There is significant effect of main rotor input

to tail rotor (cross coupling).• With the zero input to the main rotor, the

system is stable at 0.9326rad .

REFERENCES• [1] Twin Rotor MIMO System 33-220 User Manual, 1998 (M/S Feedback

Instruments, Crowborough, UK).• [2] Ahmad, S.M., Shaheed, M.H. Chipperfield, A.J and Tokhi, M.O.,

“Nonlinear modelling of a twin rotor MIMO system using radial basis function networks ”, IEEE National Aerospace and Electronics Conference, 2000.pp 313-320.

• [3] Ahmad, S.M., M.H. Chipperfield, A.J and Tokhi, M.O., “Dynamic modelling and optimal control of a twin rotor MIMO system”, IEEE National Aerospace and Electronics Conference, 2000.pp 391-398

• [4] Lu, T.W. , Wen , P. ,”Decoupling control of twin rotor MIMO system using robust deadbeat control technique” , IET Control Theory Appl. , April 2008, Volume 2, Number 11, .pp 999-1007.

• [5] B. Kada, Y. Ghazzawi, “Robust PID Controller Design for an UAV Flight Control System” Proceedings of the World Congress on Engineering and Computer Science 2011 Vol II, WCECS 2011, October 19-21, 2011, San Francisco, USA.