A quadrotor helicopter has been developed intended for future use as an aerial vehicle test bed.
The developed vehicle is able to perform all the basic functions needed for future development and has been constructed in such a manner that is easy for others to develop and change the existing design. This report documents the research and development of this platform and also gives guidance in regards to its future development and possible projects that could be based off of the platform.
Introduction
The development of small autonomous aerial vehicles is an area of interest that many researches wish to explore. There is currently a large range of projects and research topics emerging in this field .Thus it was decided to construct and develop an aerial vehicle that would be a base for future projects in this field of research.
Autonomous aerial vehicles are true mechatronic systems that combine elements of mechanical, electrical, software and control engineering. The amount of time needed to be spent constructing an entire vehicle to undertake research on a small facet of autonomous aerial vehicles is too time consuming, thus the ability to use an already constructed platform to build the desired experiments on will greatly speed up research in the future.
Preliminary research has shown that the most versatile and mechanically easy to construct autonomous aerial vehicle is a quadrotor helicopter. This is due to the fact that quadrotors can be fully controlled solely by varying the speed of the four rotors and no mechanical linkages are required to vary the rotor blade pitch angles as with a conventional helicopter.
This report will cover research into previously published papers on quadrotors in order to understand how they are commonly built and controlled as well as researching an already existing quadrotor control board that is available for purchase.
The report will also document research, design and construction of our own quadrotor helicopter that is planned to be used as a test bed for future projects at
Massey University. Conclusions will then be made on the current state of the project and suggestions and recommendations for future research projects and ways the current design can be improved will be given.
A quadrotor helicopter was developed for the purpose of creating an aerial vehicle test bed. Major work has been undertaken in the designing and constructing of the physical vehicle and basic software has been implemented for communication with a computer via RS232, motor speed control as well as the beginnings of an inertial navigation system. A testing station has been constructed so that future developments in control strategies can easily be tested without introducing unnecessary risks to hardware and operators.
What Is A QuadCopter and How It Works
A QuadCopter is a helicopter with four rotors, so it’s also known as quadrotor. Because of its unique design comparing to traditional helicopters, it allows a more stable platform, making quadcopters ideal for tasks such as surveillance and aerial photography. And it is also getting very popular in UAV research in recent years.
The Quadcopters exist in many different sizes. From as small as a CD up to something as big as one meter in width.
On a regular helicopter has one big rotor to provide all the lifting power and a little tail rotor to offset the aerodynamic torque generated by the big rotor (without it, the helicopter would spin almost as fast as the propeller)
Unlike a helicopter, a quadrotor has four rotors all work together to produce upward thrust and each rotor lifts only 1/4 of the weight, so we can use less powerful and therefore cheaper motors. The quadcopter’s movement is controlled by varying the relative thrusts of each rotor.
These rotors are aligned in a square, two on opposite sides of the square rotate in clockwise direction and the other two rotate in the opposite direction. If all rotors turn in the same direction, the craft would spin would spin just like the regular helicopter without tail rotor. Yaw is induced by unbalanced aerodynamic torques. The aerodynamic torque of the first rotors pair cancelled out with the torque created by the second pair which rotates in the opposite direction, so if all four rotors apply equal thrust the quadcopter will stay in the same direction.
To maintain balance the quadcopter must be continuously taking measurements from the sensors, and making adjustments to the speed of each rotor to keep the body level. Usually these adjustments are done autonomously by a sophisticated control system on the quadcopter in order to stay perfectly balanced. A quadcopter has four controllable degrees of freedom:Yaw, Roll, Pitch, and Altitude. Each degree of freedom can be controlled by adjusting the thrusts of each rotor.
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