High-Flyer FYDP Brought to you by Group 16
Flying high above the big blue sky
Overview
The airship operates with four main components: The hull, the gondola, the mobile phone, and the tilt controller. The hull is designed to be filled with enough helium to be just over the lifting capacity of the payload. This ensures that there is enough buffer lift if problems occur, which can easily be calibrated by adding additional weights to the center of mass.
The gondola attaches to the helium filled hull and houses all of the electronics that enable successful operation of the vehicle. Inside is the microcontroller, multiple sensors to determine range and altitude, power distribution circuits, and a lithium polymer battery. The tilt controller operates on a servo and gear train to enable the motors and propellers which drive the vehicle to be tilted up and down and enable verticle climb or descent.
The mobile phone is the component that allows image processing to occur which can lock on a target based on colour and give the microcontroller the position of said target for either tracking or following.
The Hull
The hull is made out of a strong mylar composite which allows for easy construction as the shape can be created by ironing a preset outline. The shape is designed so that there is an aerodynamic shape on the front and a more rounded curve on the back for attaching the fins which are made out of balsa wood. The entire contruction is made from three flaps of individual mylar which are joined together; using three folds instead of the usual two allows for a more cylindrical shape and better aerodynamic performance. The hull contains approximately 1.5 meters cubed of volume which is enough to lift over 1 kg of weight if pure helium is used.
Gondola
As stated, the gondola is the means of housing many of the most imporant components of the airship. Inside is the microcontroller which is the brains of the operational structure of the vehicle. It collects information from the various sensors attached to the sides and bottom of the encasement and uses a control algorithm to determine how fast the motors should turn, at what speed difference the left motor should turn from the right, and the tilt of the propellers. The battery connects at the back to provide addtional room for the components inside. There are two power distribution circuits; one distributes the 7.4 volt power from the battery to the electronic speed controllers and to the microcontroller. The other circuit takes power from the UBEC (Universal Battery Elimination Circuit), and divides it up for use by the sensors.
There are a total of two infrared sensors on the gondola each pointing outward on the sides of the ship. These detect the longitudinal distances between the nearest obstacle and pass the information to the controller. There is a barometric sensor attached to underside of the gondola that measures the altitude; there is also an ultrasonic sensor pointed downwards to help calibrate the data obtained from the barometric sensor. Having two sensors that aid each other in measurment increases the likelyhood of correct measurements.
The gondola is made of balsa wood which is a very light wood composition that allows the airship to stay light.
The Design of the Airship
The Tilt Controller
The tilt controller is a means to adjust the height of the airship without introducing additional motors. Vertical climb is achieved by simply tilting the propellers upward, and descent is conducted by decreasing the tilt. The entire operation runs through a lightweight but powerful servo that turns a gear train connected to a metal shaft where two motors are attached. These motors are connected through flexible cables provided by the electronic speed controllers which allow the tilt to be properly adjusted.
Android Phone
Having a mobile phone increases the computational capacity of the airship singificantly. The android phone contains enough memory and CPU power to conduct image processing with ease. The program developed on the phone allows the airship to lock in on a specific colour and shape and thus perform object tracking. This tracking can be performed by the vehicle then by the aid of the controller which is implemented on the Arduino. The picture on the left depicts the software in demonstration mode where it has locked in on the red box in front of it, and passed the relative coordinates of the distance to the Arduino in three dimentions to the serial port via USB.