Sunday, November 18, 2012
Wednesday, March 28, 2012
A few months ago, some college colleagues and I started work on a prototype for patent number 7,535,358 B2, Method and Apparatus for Electronically Tracking Luggage. This was the Xerox fellowship project that our group had to complete for the semester. Having led the effort and tackling the hardware aspect, I decided to publish a small report on the work that was accomplished along with the design details. All the hardware that was used is open source and cost around $250. Here is a list of the hardware used:
Sparkfun GSM cellular module with patch antenna
Adafruit SD logger Shield
EM-406A GPS module
6 AA Rechargeable batteries
Photocell (light sensor)
Medium OtterBox for the enclosure
The device would be placed in a piece of luggage with the photocell and reed switch as the primary triggers. The SD card shield would record an entry onto the SD card every minute, with the Unix timestamp, light sensor and photocell value, latitude and longitude. The time is kept by the RTC on the SD logger shield. If the light sensor or the reed switch thresholds were surpassed, the system would immediately send an SMS through the GSM module to a Twitter account to indicate that the bag had been opened.
Here is the Arduino code for the final device…excuse me for the crappy coding :)
The logged data can be analyzed in the following ways:
The owner of the bag could upload the logged data using a simple uploader script to a website that we built. Once uploaded the data is parsed and plotted indicating spikes in the light sensor or reed swtich readings along with a Google map showing the locations in the spikes. It is always possible that the GPS module would not have a fix as the bag enters structures that inhibit GPS fixes.
A webpage had also been constructed to scrub the last 10 tweets posted via SMS to the Twitter account. Once scrubbed, the Tweet was parsed for the timestamp and latitude/longitude data. The information was then pushed onto the Google maps API where the location information was pinned. One of the hardest things to do was to fit everything in the Otterbox without shorting/crushing my electronics. It worked out well. The Otterbox is an awesome enclosure btw.
Please contact me with any questions regarding this project. I would be more than happy to assist. Thanks to all the folks at Adafruit for your assistance and awesome documentation. Keep doing what you are doing, you are inspiring budding engineers such as me to try stuff they have never before. Your prompt responses to my forum questions really helped in getting this thing to work. This device is a bit ahead of its time in terms of regulations to be used on an airplane. Once the Feds allow cellphone use on airplanes, this device would be able to fly!
Sunday, February 19, 2012
I set out to develop a system that would allow me to monitor the production and consumption of energy for a solar panel set-up. The solution was to use XBEE wireless sensors to capture current/voltage data and relay that to a base station connected to a laptop. The information would then be sent to the internet. The raw data received from the XBEEs would be parsed using Python. The KWH consumed would be logged. More details would be posted as the project progresses.
Wednesday, December 28, 2011
I bought the Sparkfun Cellular Shield SM5100B with an Arduino UNO, and Quad-band Wired Cellular Antenna SMA antenna. Hope to use it for an upcoming project. Here’s how I set it up. I followed the instructions at http://tronixstuff.wordpress.com/2011/01/19/tutorial-arduino-and-gsm-cellular-part-one/ to get the cell module working/ Everything went well till I got to the part for setting up the band for the US. I was using a T-mobile post paid SIM card. T-mobile is on the GSM850&PCS1900 i.e AT+SBAND=7. This was the message on startup +SIND: 1 +SIND: 10,'SM',1,'FD',1,'LD',1,'MC',1,'RC',1,'ME',1 +SIND: 3 +SIND: 4 +SIND: 8 (loss of signal)
I eventually figured out that the band setting for the US was not set correctly on the module. I did that by using ZedLeps code modification at http://www.sparkfun.com/products/9607, uploading the sketch to the board, and then entering AT+SBAND=7 in the arduino serial monitor. This did the trick. I also had to hit the reset button on the UNO using a piece of plastic to reach under the shield once I made the change. This time around, success! Got +SIND: 11. eventually managed to send text messages and receive a call.
Sunday, October 9, 2011
I bought a SD card logger shield for my Arduino Duemilanove to be used on a project. The kit was ordered from Adafruit and was assembled without issue. Ladyada has all you need to assemble and test the shield. Worked great! This shield has many applications and provides a simple way to log data from a temperature or light sensor with a time-stamp.
Tuesday, August 30, 2011
Monday, August 1, 2011
I bought a Dynam Hawk Sky a couple of weeks ago from Nitroplanes.com and here
is a little review.
The package was delivered without any issue. The foam parts were packaged well. Plugged in the LiPo to charge on the provided balance charger. The charger gave a wierd high-pitched sound when charging, I guess that was normal as the 2 LEDs were green. It took about 45 minutes to charge. The instruction manual is poorly written, so I would suggest looking for some help online. If you have previous RC experience, most of the construction is common sense. The horizontal stabilizer and the rudder were attached using 20 minute epoxy ensuring that the parts were square. The rudder and elevator clevises are a couple of brass attachements with a screw to hold the push-rod in place. It was quite flimsy in my opinion, will get to that in a minute. I let the epoxy harden overnight. The aeileron servos/push-rods came installed. The wing installs by sliding each side into the fuselage after connecting the servo leads. There is a plastic tube that goes between the wings to add some strength. The wings are held in place by the tightness between the wing root and fuselage. I found that a little unsettling, hence added a couple of pieces of electrical tape for good measure. I would have hated for the wings to come loose in flight :)
I wasn't too sure about the 2.4GHz radio system that came with the plane, so I replaced the transmitter/receiver with a Tactic system from another plane that I had. The stock servos worked with the Tactic system, so I left them in place.
The motor connections required a bit of maneuvering as the motor wires had to be pulled through the foam area on the mount into a vent hole just under the motor mount (see pic above). This required a bit of patience as the hole was very small.The first flight was uneventful. The brushless motor has plenty of power for a good climb. The plane is very dosile and it is difficult to do rolls with the huge wingtip dihedral.
My first take-off was on asphalt using the landing gear. Later did hand-launches. It glides really well as I was flying at 1/2 power with a flight time of about 20 minutes. The stalls are predictable, with a bit of spiral to the left. Since the plane glides very well without a significant drop in airspeed, the landing descent was started early on idle. I had to use a bit of down elevator to keep the decent as it would have otherwise over-shot my landing mark. The rudder works well at low airspeeds as well. The first landing was a bit hard and the elevator clevise came loose. I ended up twisting the pushrod in the hole of the control horn to keep it in place for the second flight. I would recommend that this be done for all surfaces. I tested a payload capability with a 160g battery pack, and the plane handled it without issue. I will eventually be using the plane for my Ardupilot Mega autopilot. There is a generous amount of room in the fuselage as the elevator and rudder servos are mounted outside.
Ultimately, I think that the Hawk Sky is a great beginner plane and defintitely a good platform for an autopilot system. It looks good too!