1. 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

2. 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

3. 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

4. VERTICAL PART(1DOF)
• MAIN ROTOR :
using Newton torque equation –
And,
Also,

5. Thus, SIMULINK MODEL –

6. HORIZONTAL PART (1DOF)
• TAIL ROTOR:
same as equations in main rotor –

7. Thus, SIMULINK MODEL –

8. • Motor transfer function and torque function
of speed of rotor.
Tail rotor-
Main rotor-

9. Simulation and Results (1DOF)
Response of tail rotor

10. Response of main rotor

11. COMPLETE 2DOF MODEL

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

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

15. Response of main rotor to different step input

16. 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 .

17. 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.