Altitude Control System Case Study

Introduction

I will be designing an altitude control system for a helicopter. This system will only apply for vertical motion. For a helicopter system, a forward or backward tilt is known as pitch and a sideways tilt is known as roll. The overall amount of lift is dependent on all the blades’ angles of attack. They need to all be adjusted at the same time, by the same amount to affect ascent or descent.

Inputs and Outputs

In most cases, a helicopter makes use of four flight control inputs, namely: cyclic stick, anti-torque pedals, throttle and collective lever. The collective is used to change the pitch of all the rotor blades at the same time by changing the angle of attack of the main rotor simultaneously on both blades [2]. Twisting the

To descend, the collective would be lowered gradually. As the required height is approached, the collective would be lifted slowly to decrease the rate at which the descent is occurring, and then again until the hovering state is acquired.

A helicopter’s altitude system needs to be controlled because to achieve the various movements of a helicopter, very careful adjustments and balance of the controlling inputs needs to occur. If one input is slightly off-balance from the others, control of the helicopter could be lost which may have detrimental effects on the passengers and the people/environment around where the helicopter may crash. Effective control over this system would result in a much safer and more efficient utilisation.

Passenger Considerations

During lift off, target altitude approach and touchdown, there needs to be gradual changes in acceleration before the helicopter comes to a complete stop or enters the hovering state. This will allow for a more comfortable experience for the passengers. Jerking motions or whiplash would not be

Block Diagram

Key: u(t): Input in volts c(t): Collective signal

FT: Thrust

FL: Lift

FG: Force due to gravity

FN: Net force y(t): Output in metres (altitude)

References

[1]M. Brain and W. Harris, 'Flying a Helicopter: Taking Off - How Helicopters Work', HowStuffWorks, 2015. [Online]. Available: http://science.howstuffworks.com/transport/flight/modern/helicopter7.htm. [Accessed: 09- Mar- 2015].

[2] Pilotfriend.com, 'helicopter controls and components', 2015. [Online]. Available: http://www.pilotfriend.com/training/flight_training/rotary/helis.htm. [Accessed: 09- Mar- 2015].

[3] Helicopterpage.com, 'THE HELICOPTER PAGE', 2015. [Online]. Available: http://www.helicopterpage.com/html/unique.html. [Accessed: 09- Mar- 2015].

[4] Copters.com, 'Helicopter Aviation', 2015. [Online]. Available: http://www.copters.com/pilot/attitude.html. [Accessed: 09- Mar- 2015].

[5] Stop the Chop NYNJ, 'Effects on Health', 2015. [Online]. Available: http://www.stopthechopnynj.org/effects-on-health.html. [Accessed: 10- Mar-