Preliminary Electronics

I just wanted to post the current state of our preliminary electronics design. Well, it's not so much of a design as it is components selection. The first components that we have to figure out are the ones that will supply the controller with what it needs to know about the plane. The second set it the rest including the actual main processor/controller, batteries, data links, etc. There's a lot of research that we've done that isn't reflected on this document yet including a bunch of different camera modules and wireless link we've been looking at as well as processing units. Anywhere, here it is:

Driving Needs

Flight State Parameters
1. Orientation (pitch, roll, yaw)
   a. IMU package
2. Rates (translational, rotational)
   a. IMU package
3. Acceleration
   a. IMU package
4. Airspeed
   a. Pitot-static tube and pressure transducer
5. Heading (faster refresh than GPS)
   a. Magnetic compass
6. Global position
   a. GPS module
7. Global velocity
   a. GPS module
   b. IMU package (acceleration integration)
8. Altitude
   a. General (pressure)
      i. Pitot-static tube and pressure transducer
   b. Back up
      i. GPS module
   c. Detailed (near ground for landing)
      i. Laser range finder
      ii. Sonic range finder

Other Electronics Needs
1. Processing unit
   a. Gumstix + Robostix
   b. ATmega168 microcontroller(s)
   c. TERN Inc. i386-Drive
2. Power supply
   a. Lithium-ion batteries
   b. Nickel metal hydride batteries
   c. Solar
3. Data Link (radio communication)
   a. Radio modem
4. Camera
   a. Camera
   b. Wireless link
5. Servos
   a. http://www.pololu.com/products/servos.html

Solutions

IMU package
Parameters: Orientation (pitch, yaw, roll), rates (translational, rotational), acceleration
Product choices:

IMU 6 Degrees of Freedom - v2 with ADXRS150
http://www.sparkfun.com/commerce/product_info.php?products_id=8192
Price: $324.95
Dimensions: 2" × 2" × 1"
Weight: 29 grams (0.064 lbs, 1.0 oz)

IMU 6 Degrees of Freedom - v2 with ADXRS300
http://www.sparkfun.com/commerce/product_info.php?products_id=8192
Price: $324.95
Dimensions: 2" × 2" × 1"
Weight: 29 grams (0.064 lbs, 1.0 oz)

Digital compass
Parameters: Heading
Product choices:

Compass Module - HMC6352
http://www.sparkfun.com/commerce/product_info.php?products_id=7915
Price: $59.95
Dimensions: 2" × 2.5" × ?
Weight: ?

Compass Module - Vector 2Xe
http://www.sparkfun.com/commerce/product_info.php?products_id=236
Price: $84.95
Dimensions: ? × ? × ?
Weight: ?

GPS module
Parameters: Global position, global velocity, heading, backup altitude
Product choices:

20 Channel EM-406A SiRF III
http://www.sparkfun.com/commerce/product_info.php?products_id=465
Price: $59.95
Dimensions: 1.18” × 1.18” × 0.42” (30.00 mm × 30.00 mm × 10.70 mm)
Weight: 16 grams (0.035 lbs, 0.56 oz)

LEA-5S ROM-based u-blox 5 GPS Module with KickStart
http://www.abacuscity.ch/abashop?s=142&p=productdetail&sku=78
Price: $99.00
Dimensions: 0.67” × 0.87” (17 mm × 22 mm)
Weight: ?

Pitot/static tube & pressure transducer
Parameters: Altitude (pressure), airspeed
Product choices:

RCAT 6” Stainless Steel Pitot-Static Probe
http://rcatsystems.com/accessories/pitotprobes.php
Price: $79.95
Dimensions: ? × ? × ?
Weight: ?

Kulite Pressure Transducer
http://www.kulite.com/pdfs/pdf_Data_Sheets/ET-3DC-312.pdf
Price: ?
Dimensions: ? × ? × ?
Weight: ?

Sonic range finder
Parameters: Altitude (detailed)
Product choices:

Maxbotix LZ-EVx
http://www.sparkfun.com/commerce/product_info.php?products_id=639
Price: $24.95
Dimensions: 0.785” × 0.870” × 0.735”
Weight: 4.3 grams (0.0095 lbs, 0.15 oz)

Radio modem
Parameters: Data link
Product choices:

XStream OEM RF Module
http://www.digi.com/products/wireless/long-range-multipoint/xtend-module.jsp
Price: $179
Dimensions: 1.6” × 2.825” × 0.665”
Weight: 18 grams (0.040 lbs, 0.63 oz)

AeroComm 4790-200
http://www.aerocomm.com/rf_transceiver_modules/ac4790_mesh-ready_transceiver.htm
Price: ?
Dimensions: 1.65” × 1.9” × ?
Weight: < 20 grams (0.044 lbs, 0.71 oz)

First Iteration of Aircraft Ready

The first iteration of the aircraft has been completed. Attached is a photo of the model built using AVL, an aerodynamics and aircraft stability analysis software. Numerical flight simulations can now proceed using the results generated by AVL.

Software to Hardware

Utilizing the really nice USB serial interface to the microcontroller, I managed to get a simple but effective software to hardware interface. On the microcontroller I coded a simple program to recognize commands sent as ASCII over the serial interface and respond based on the request. So the microcontroller was controlling two servos and talking with the Wii Nunchuck and would send data from the back to the computer if the computer sent a request for it.

On the computer side I wrote a .NET program in C++ that would connect to the serial port. Writing the program acted as a wonderful foundation for what will eventually be our own proprietary ground station software. The program sports a command line that you can just to write your own commands to the microcontroller. Whether it will recognize it or not depends on the microcontroller. Anyway, so it will display what is being received in one panel and a sort of orientation instrument in another panel. The orientation instrument is updated based on returning data on the Wii Nunchuck accelerometers. That data is requested by the program either by hand using the command line or about every 10 milliseconds. If the program picks up data coming back, it parses it to see what kind of data it is. If it recognizes something then it picks out the important details and does whatever it's supposed to do with it.

Anyway, I hope you guys will see the ramifications of this bit of progress. It's essentially a proof-of-concept for a proprietary ground station program. Communication with hardware, graphical display, Windows controls handling, message handling and parsing, and more were achieved with this small program. That's basically everything we need to make a bare bones system. To make a more advanced one, such as one that will utilize Google Earth and such, will take some more tinkering.

Also, on Wednesday, January 25th, I held a kickoff meeting of sorts for the project. This is our first time opening it up to other people. The attendance was nice and overall it went fine. It looks like people share the general objection to simply buying commercial products and putting it together. Hopefully that will motivate people to work hard on actually engineering a final product.

New (Sorta) Finds

So, while I was busy not listening in class today, I found some more links to parts that we may want to use.

KT&C Camera:
http://www.ktnc.co.kr/product_07.asp
If you look to the left of that page, you will also find lenses for the camera.

Panasonic Camera and Lens: http://catalog2.panasonic.com/webapp/wcs/stores/servlet/ModelList?storeId=11201&catalogId=13051&catGroupId=14458
http://catalog2.panasonic.com/webapp/wcs/stores/servlet/ModelList?storeId=11201&catalogId=13051&catGroupId=14687

Future Hobbies Video System (or other parts if you just go to Future Hobbies):
https://www.futurehobbies.com/items_detail.asp?id=1&item=70

Review of Pan/Tilt gimbals (probably just use for ideas):
http://blog.wired.com/geekdad/2007/07/testing-three-p.html

Pitot Static Tubes (they call them probes): http://rcatsystems.com/accessories/pitotprobes.php

Pressure transducer to "read" the probe: http://www.kulite.com/reference/Pitot-staticTransducer.pdf

That's all folks!!

We're Alive

So some good news came in today. Well, it's generally not good news that $500 was withdrawn from your bank account, but in this case it is because it means our application for the project went through. While I'm at it, why is information for this competition so hard to find?! I can't even find a contact point for the competition. The website doesn't even have standings from previous years or an archive of reports (it does have the 2007 papers though, linked to the right). Anyway, the links to the right were reorganized a bit. A few more were added too, check it out.

In terms of progress, the currently small team has started its first tasks. Although most of it is research it is rather important research. Matt and I will be looking into flight state acquisition and the many methods to achieve it. Hopefully we'll get those findings onto the blog. Gerard and Jerry in the mean time will be doing an initial design and sizing of our plane. Configuration conditions such as using a high wing for stability instead of complicating manufacturing with a dihedral are about the things they'll be considering. By the end of it we should have a good idea and sketch of what the plane will look like and where the payload will be. Gaurav will be spending some time become our team expert on gas motors, something we need considering that we've never made a plane with a gas motor before.

Worth noting is that our aircraft performance & stability and aircraft design professor (er, lecturer) Damian Toohey is willing to officially advise us on the project. No official adviser is necessary, but it is nice to know that he's ready to help when we need it. He's worked on autonomous formation flying before dealing with IMU's, gas motors, and all that good stuff. He's even made gyro-stabilized camera platforms on blimps before, for fun.

In other news, I've personally ordered a GPS module recently; it should come in this week. It's a unit I bought personally to play with, but hopefully my selection will also be a sufficient one for the project. Even if it isn't, the experience to come from playing with it should be useful enough. I also received my shipment of four extra ATmega168 micro-controllers that work with the Arduino. Hopefully I'll have some cool parallel processes going for things such as input conditioning and data buffering pending query. Matt also stumbled upon the AeroSim blockset for Simulink which should help us rapidly prototype the controller. You can find more about it at http://www.u-dynamics.com/