Quadcopter Requirements and Parts Planning - Phase Alpha

Hi!  My name is Jordan!  This will be my first blog entry for our quadcopter project.  I'm very excited to get started on the project, but my Dad is advising me to calm down and run this like a true design project.  He said that "we need to limit our initial goals to the basics, so we don't tie up too much money in the project before we get it to fly properly", so we will be leaving the GPS tracking and GoPro Hero 3 purchases for a later time... dang it!

On a 2-mile walk with the family, my Dad and I got a chance to have a long talk about the quadrotor project.  We talked about the list of requirements for the first version of the project, which we are calling "Quad Alpha".  We also discussed things like Beta and revision numbering for the hardware and firmware.  My Dad insists on calling the programming part "firmware", probably because of his work experience.

List of "Quad Alpha" Requirements

·         Autonomous Flight
·         Autonomous Take-Off
·         Autonomous Landing
·         Maintaining Level Flight
·         Object Avoidance in X/Y/Z Directions
·         Microcontroller control (required for autonomous functions)
·         Data Communication with Controller Board to send basic commands, like

o   begin take-off routine

o   begin landing routine

Starting with the list of requirements above, we discussed the parts that would be needed.  For the basic flight system, we would need four motors, two clockwise and two counter-clockwise rotors (explained here), four Electronic Speed Controllers (ESCs), a controller board, a battery and a frame to hold them all together.  We are going to forego the full remote control at this time, mainly because of the high cost and small number of commands we need to send.  We will try to send commands to the device through some type of simple data communication, like infrared, for the Quad Alpha phase.   

To maintain level, we will need a gyroscope.  To do take-off and landing, we will need a longer-range sensor on the bottom.  Dad suggested some type of sonar sensor.  To do object avoidance, we will need a single long-range sensor and four shorter-range sensors.  I used ultrasonic sensors for proximity sensing with my Lego Mindstorms NXT 2.0 and in First LEGO Robotics League.  I'm very familiar with their usage.  We talked about the placement of each part on the body of the quadcopter, like the sonar sensors on the top and bottom of the quad so that it can determine how high it is flying when indoors.  The ultrasonic sensors would be placed under the four rotors so the program could determine distances between objects and the rotor ends to protect the rotors.  The gyroscope would be mounted in the center of the quadcopter to sense the small changes in level.

We created a "Bill of Materials" in a spreadsheet to keep track of the items for this part of the project.
 

Part Description	Quantity
Motor	4
CCW Rotor	2
CW Rotor	2
ESC	4
Microcontroller Board	1
Quadcopter Frame	1
Gyroscope	1
Sonar Sensor	2
Ultrasonic Sensor	4
Battery Pack	1

For the next blog entry, we will put together a schematic showing how all these parts will be wired together.  This will help us pick the right parts the first time.