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Nov 19 2010

XBee Pro 900 & Brushless Controller 2.0 Incompatible?

XBee, why you no connect!This week I attempted to determine the reason behind the XBee connectivity problems. With Chris’ help we tested a few things we believed that could be the cause of the problem. First we tested if the field laptop was the issue behind the connectivity problems. Using another laptop we spaced the Hexakopter and the laptop about 70m apart and sent waypoints as well as running a motor test. We were surprised when the field laptop preformed at par with the other laptop and neither lost signal through the test. After ruling out the laptop, we decided to change the XBee’s and found that the Xbee’s performed consistently regardless of which pair was used. With both tests showing complete functionality between the XBee’s we decided to fly the Hexakopter outside.

During the first test flight we had no issues with the XBee’s losing signal with the laptop. However, after the flight was completed we started getting connection issues with the XBee’s. In a last ditch effort to find the issue we tried using another Hexakopter that ran on the Brushless Controller 1.0. After running both Hexakopters for about 5 minutes, we started noticing that the Hexakopter with the BL 2.0 was getting connection errors while the other Hexakopter (runnig on BL 1.0) had no connection issues. We also tested both Hexakopters on different laptops and XBee pairs and obtain similar results.

We concluded that the new brushless controller was the main cause behind the XBee’s failure to connect after a flight.


Edit: Today I found out that the Hexakopter using the BL 1.0 had similar connection issues outside – totally making our previous work null and void.

Nov 19 2010

Field Work Progress Report 11/19/2010

As of today, I have three plots left to survey in order to complete the HR area that is allowed to be studied according to the UMBC Police. After an encounter with a police officer regarding my presence in the area, he mentioned that I should not attempt to go beyond the fence they had placed there. This means that data cannot be fully collected for the area, but a vast majority of it has been gathered.

The 3P setting was used extensively this week and after getting the hang of it, it really made the process much faster. Had it not been for leaf-off conditions slowing the identification down I would be able to move along much faster.

Next week will mark the end of field work for the season as it is growing VERY difficult to collect the field data and geo-referencing will begin for the remainder of the semester.

Nov 18 2010

ArduPilot Assembly

Last Friday all of the ArduPilot parts had arrived and work had begun on assembling each of the individual components. This process was relatively simple thanks to the instructions on the DIY Drones webpage. Throughout this past week I’ve been working on getting the GPS, IMU, ArduPilot shield and the Futaba transmitter and receiver to communicate with one another. I’d like to say that this was straight forward as well, but unfortunately the ArduPilot has already been through some rough times. The first problem arose during the pre-solder process in which one of the electrical conduction pads had been removed along with the imbedded circuit wire that was attached. Although This was eventually fixed by simply bridging the header pin to the exposed wire the connection is now vulnerable to being pulled apart. As of now however, the connection has not caused any immediate problems. After this was fixed I had begun to attach the components and test their ability to “talk” to one another. This is when I had noticed that the ArduPilot board, after working perfectly for the past few hours, would either not turn on or only turn on for a few seconds under very specific powering conditions. After several hours of refining solder joints and probing the board with a volt meter I had noticed that one of the imbedded circuit wires had developed a hairline crack resulting in a poor electrical connection. This was eventually resolved by creating another bridge between one of the board’s components and a resistor. Although the ArduPilot board may not look like new, it at least functions like it’s new.

There is however, some good to come of all this trouble. I’ve become hypersensitive when working on circuit boards to sounds, smells, small sparks, overheating, smoke and fire; all of which to some degree, are a part of working with electronics. Well…maybe not the smoke or the fire parts in my case, but I’m certainly more careful with circuitry now than I was before. Nathan Seidle, founder of SparkFun electronics once declared “The New Rules of Electronics” as follows: “Build it and plug it in. If it sparks, unplug it. If it smokes, turn it off. If it heats up, check it, and plug it back in. Don’t be afraid of trying something new. That’s when you’re having the most fun.” That being said, I think I’ve been having a bit too much fun as of late.

Everything is in working order now. The IMU is detecting acceleration and moving the servos accordingly. The toggle switch for designating the flying mode is functional and the GPS is able to connect to satellites. This next week I’ll begin to work with getting the XBees to communicate with one another and installing all of this into the EasyStar’s frame. I’ll probably be doing a flight test without the ArduPilot sometime next week as well to get a feel for where the center of gravity should be located.    

Nov 12 2010

EasyStar Progress

On Friday of last week the EasyStar had been delivered from the Tower Hobbies website. Although the ArduPilot components were ordered on Monday of this week, they have not yet arrived. In the meantime I had started to assemble and modify the EasyStar such that when the parts are delivered I can focus on getting the ArduPilot set up and making modifications to the open source code.

As of now, two plastic hinges have been inserted into the bottom of the fuselage which enable the frame to be quickly disassembled for easy access to the internal electronics and camera. I have also started to carve out a gap in the fuselage for the SD4000 digital camera. A hole was also added to the bottom of the fuselage which will enable the SD4000’s camera lens to be fully extended while inside the EasyStar. Once the ArduPilot parts are delivered I will begin to carve out sections within the fuselage that will house each of the ArduPilot’s components. The image illustrated below shows the respective locations for each of the components. It’s likely that this layout will be refined as the build continues to insure that the center of gravity is in the correct location.

Nov 12 2010

Good as new...well almost.

This week I focused on rebuilding the Hexakopter that crashed while trying to fly the "trifecta" camera setup. It involved switching out the three bent arms and replacing them. I used the arms from yet another crash victim from the same day as the scanning camera test. The hardest part wast not removing the arms but resoldering the wires but not being able to move the brushless controllers as much as I would have liked. There are still some minor things that I noticed today that need to be fixed such as the led strip has a loose connection, and not all the props are on. However even with these minor repairs, it still should be able to fly when needed.

On a side note, I think it would be best if we did not clip the motor wires and other connection wires short. This way, in the future we have easier access to the underside of the brushless controllers allowing for faster repairs.


Nov 11 2010

Field Work Progress Report 11/11/2010

Progress As of 11-11-2010


Red = Un-measureable due to new fence

Green = Tree Data collected

Yellow = Remaining plots

Notes About this week:

The trees seem to be changing slower than anticipated, which should easily provide enough time to finish up the remaining plots on schedule. I am averaging roughly 1 plot every half hour or so without any complications although issues with the hypsometer seem to be re-occurring.The hypsometer features a 3P mode as discussed earlier, but as of late it has been giving inaccurate measurements. Perhaps this requires some more time practicing with this mode and comparing it to 2PL mode. Doing identification seems to be getting slightly easier, but the leaves are definitely still very necessary for me to make a fully accurate identification.

Nov 08 2010

Don't Forget to Backup!

Quick! Find the corrupt data!  

I had made the mistake of not being careful and meticulous with data backups a few months ago when I came in to the lab to find my primary data drive was toasted and some of my data was gone.  I do not think that that was a major loss, but I made sure to get my redundant backups up and running.  I have also been encouraging the practice with friends and loved ones ...  I don't think my parents have a clue what a Terabyte is though.

Out in the field I also backup data, mostly for fear of physically losing the media.  I have been in the habit of making a local copy of images collected during the day on the laptop and typically have enough SD card space to keep the originals on the cards.  This morning when I came in to dump the data from the weekend I kept getting an error that I couldn't transfer data from the card to my hard drive.  After some investigation I discovered what is seen in the image in one of the main image folders on a Sandisk Extreme 30MB/s 16GB SD card I had used during a flight.  In addition, Windows thought the card had 78GB of data on it!  I get the same results mounting the card in Windows and on my Macbook, and no problems reading other cards on the same Dynex card reader.  I also discovered that about 1000 photos were gone from the set and quickly panicked to find the laptop and confirm my backup copy was intact.  It was and I proceeded to transfer the good data over to the main system where we have nightly backups.

So do we wipe and reuse the card, perhaps also defragmenting, or is it time to find a replacement?  Considering the value of the data, it is probably time for another card.

Of course, the other explanation is that the card did some time traveling over night...

Nov 05 2010

Finalized ArduPilot Parts List

Last Friday the Ecosynth Team had placed an order at Tower Hobbies for an almost ready to fly(ARF) EasyStar. Although it has not yet arrived this progress had encouraged me to finalize the complete parts list for the EasyStar project. Over the past few weeks the ArduPilot Shield V2 had been listed as being out of stock on the SparkFun Electronics website. Because of this I have been holding off on creating this list until it was confirmed that this component wasn’t in the process of being replaced by an newer version. As of 11/3/2010, all of the required components are in stock, each of which is listed below.

  1.          Component                   Price/unit
  2. ArduPilot                               24.95
  3. ArduIMU+ V2.                        99.90
  4. ArduPilot Shield V2                 57.20
  5. uBlox 5 GPS                           87.90
  6. GPS Adapter                          19.50
  7.   GPS Cable                            1.95
  8.   Break Away Headers               2.50
  9.   Programming Cable                17.95
  10.   Servo Extension Cable(x4)       1.50
  11.   Air Xbee4                              2.95
  12.   Air Xbee Adapter                    10.00
  13.   Air Xbee Jumper Wires            3.95
  14.   Ground Xbee                          44.95
  15.   Ground Xbee antenna              7.95
  16.   Ground Xbee Adapter Board      24.95

The total cost comes to $452.60, not including the EasyStar, radio gear or battery pack. Although the Xbees aren’t required for autonomous flight they make revising and uploading waypoints in the field more convenient as well as relay live updates to a nearby field computer. For the initial test flights I plan on using a 11.1, 2300 mAh lipo battery which will eventually be upgraded to a higher capacity battery in order to achieve a total flight time of 15 minutes.

Once the EasyStar arrives I will begin to modify the frame and install the brushless motor and ESC. An order for the ArduPilot components will hopefully be placed within the next few days. I have already downloaded the Arduino Program Editor and had started to modify the code such that it will be compatible with all of the above components. I have already spent a significant amount of time reviewing the code and trying to understand what the program is doing and the methodology behind its operation. The majority of my focus has been on the IMU sensor and the process by which it records measured data and transforms it into values that define the plane’s attitude with respect to the earth. Bill Premmerlani had posted a tutorial on the mathematical operations involved in this procedure here.

I had previously mentioned the possibility of integrating a self-deploying parachute into the EasyStar’s fuselage which would enable the plane to land autonomously in small fields. I had recently come across RocketChutes.com, a website that sells inexpensive model rocket parachutes ranging in size from 12’’ to 48’’  in diameter. A chart on RocketChutes.com indicates that their largest parachute (48’’) would be ideal for 48-64oz rockets; well above the weight capacity that would be required for a fully loaded EasyStar. Once this platform is able to fly autonomously I will continue to look into alternative features such as this.