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Apr 26 2012

Arducopter Progresses, Octocopter Components Still Arriving

It’s been slow going with the Arducopter, working with it this semester has often seemed like two steps forward and one step back.  However after several stumbling blocks like the Ardupilot board being of the older model now, and  ailing Electronic Speed Controllers:  things are starting to look up!

I was able to update the Arducopter to four brand new ESCs, since one of our big orders just came in (will get to that in a bit).   Earlier we’d had trouble calibrating the Arducopter for flight, it kept wobbling and flipping over.  I feel rather foolish now; the problem was that the ESCs were mismatched!  One had been replaced because it was suspected to be burned out.  I only yesterday realized that of course it would need four identical speed controllers to fly stabile.  Since our Octokopter order of ESCs came in, there were enough spares to outfit the Arducopter for testing.

So a new order did come in!  Our large order from DIYDrones is now in the lab: it included ESCs, propellers, power distribution boards, and Ardupilot boards.  Combined with our previous order from Aeroquad (Mikrokopter OctoXL Frame), we now have most of the components to build an Octokopter, and enough spare parts to build a second one (minus what we’re still waiting on.)  The jDrones order went out yesterday; it was mostly parts that have been out of stock until now.  This order includes the last set of components we’ll need to make a working Octo, the motors.

Things are looking good for the next gen of Ecosynth aircraft; at this point I think that Octokopter work will start as soon as summer research starts, when aircraft moves into the bigger lab.

Apr 09 2012

First Test of PVC Markers


On Thursday 4/5/2012 Jonathan and I went to HR with 2 other students to attempt to lay out the PVC pipe that will mark the 5x5 meter grid. Our plan was to lay a reference string between 2 of the serveyed points in the 25x25 meter grid. Once this was done we could measure 5 meters along this line with our wooden poles, string, and line levels to help ensure accuracy. We secured a string between the two wooden poles measured at 5 meters We would than insert PVC poles like the ones to the left at these 5 meter marks. However when we finished our first 4 points and came to the known survey point we were anywhere from 10 to 30 cm off. This was too much inaccuracy and we quickly saw that the string connecting the two wooden poles could flex, this being our cause of inaccuracy, we determined we needed a more rigid material to connect the poles. Back at the lab we found some thin metal wire and after attatching this to the wooden poles and retesting the same strategy as before the accuracy was greatly improved, at most we had a 1 to 2 cm innaccuracy with most of the corner points we plotted landing directly on the survey point.

Apr 04 2012

Hexakopter Flying and Testing the GoPro

Stephen and I practed flying the hexakoptors.  We were able to fly Roflkopter (one of the hexakopters) from the lab to the library, over the library and adjacent garage, and land on a 2ft by 2ft board.  In addition to the lirary expedition, we also practiced maneuvering the hexakopters, landing on a target, and getting them flying at the correct altitude.  Furthermore, we used the GoPro camera to capture video and pictures of the flights.  (The camera was mounted on the hexakopter.)  Unfortunately, the pictures had a lot of compression (as can be seen by the picture to the left that was taken in the lab).  Next week we will be testing to see if adjusting the setting will yield better images.

Below is a link to a video from the GoPro as we flew through Academic Row.  The first half of the video is with the distortion and the second half is the cleaned-up version.

http://www.youtube.com/watch?v=YtPkQShCR8c&context=C451b577ADvjVQa1PpcFNA2j44Y1Kwcn_6Rdo149XVXfaZn7cl70E=

 

 

Mar 21 2012

Tree mapping Technique

There have been many methods for mapping the trees within our 25x25 meter grid that we have identified. The one certatinty we have decided on is the grid must be sectioned into a 5x5 meter grid before we can begin mapping. The picture on the left shows a method found in the field guide Methods For Establishment And Inventory Of Permanent Plots. This method involves usining geometry to determine the exact point of a tree and we thought it could be more accurate and faster than other ideas. However when we went to our forrest to test we discovered that it was not only more tedious but may not improve accuracy by a reasonable amount if at all. The problems arose when we needed to take measurments on unlevel surfaces. It would involve 3 or more people with much instruction and using handfulls of equpment, it was uneffective for our purposes. We plan on going on another test run before the week ends to try another method that will hopefully work for what we need. 

References:

Dallmeier, F. (1992). "Long-term monitoring of biological diversity in tropical forest areas." Methods for establishment and inventory of permanent plots. MAB Digest Series, 11. UNESCO. Paris

Mar 21 2012

Herbert Run Update

On Monday (3/21/2012), Andrew and I went to Herbert Run to survey more points to make a grid so that we can start mapping trees.  By the end of the day, we finished enough points to have ten 25 by 25 grid points marked and ready for tree mapping.  We begin mapping trees today (3/21/2012).

Mar 20 2012

New Jersey Pinelands Fire Research Flight

This past Tuesday (3/6/12) Jonathan and I travelled to New Jersey to conduct wildfire research.

We left Monday evening and drove to the New Jersey Pinelands, where we stayed overnight at the research center.  Our first obstacle was the smoke research payload.  When Jonathan did this smoke research in the past, he had suspended the payload (consisting chiefly of a smoke detector and data logger) on a tether beneath the hexakopter.  The reasoning behind this was that we needed to keep the payload well away from the air disturbance made by the hexa's propellers.  However, the problem with this method is that the hexakopter is unable to self stabilize under a suspended payload, and ends up swinging the payload wildly and eventually crashing.

Jonathan and I did a brief test to confirm that this behavior was still present with the fire payload, it was.  As a solution, we mounted the payload on top of the hexakopter's dome.  A strip of ribbon attached to the top of the payload served to demonstrate that the propellers did not significantly interfere with the airflow though the payload when it was mounted on top.  The hexakopter was perfectly stable with the top mounted payload. 

Tuesday during the wildfire we flew from the research compound which was downwind of the wildfire in the smoke plume.  The hexakopter flew up in 50 meter increments and back down every half hour or so for several hours.  Overall our data collection was a success.  Towards the end we even had the time to mount a camera on top of the payload to take a rather jittery video of the wildfire from the air.

Feb 27 2012

SERC Leaf-off Hexakopter Mission

This past Sunday (2/26/2012) Jonathan, Shelby, and I went to the Smithsonian Environmental Research Center to fly a hexakopter mission during leaf-off.  The image on the left was taken by the camera mounted to "Sally" as it was coming in for a landing.

Since "Raven" still has what we believe is a motor controller issue (contacting Nisarg about this), we brought "Roflkopter and "Sally" to SERC.  Initially "Roflkopter" was designated the primary flight hexakopter, because "Sally" had been noticed as having stripped threads on one of the propeller mounts on top of a motor.  Since the other two holes in the propeller mount were not stripped, we still considered "Sally" flightworthy, just not primary.

Once on site, Shelby and I set up a series of twelve orange contractor buckets along the road through the forest we were surveying.  Jonathan had programmed the rough distribution of them into the dog-tracker GPS to follow when we were setting them out.  Then throughout the rest of the day during flights and other work, we used a handheld GPS tool to determine the precise coordinates of each bucket.  These coordinates will be applied to the buckets in the point cloud representation.

As it turned out, "Roflkopter" was not our best choice for primary hexakopter.  Although it was certainly flightworthy, during flight it bobbed up and down instead of flying in a straight line.  Jonathan believes it is due to the hexakopter's vertical lock setting being miscalibrated or otherwise dysfunctional. 

We decided to fly "Sally" to see if we could collect data from a smooth flight.  After some test flights, we determined that the stripped screw on "Sally's" propeller mount was not going to be an issue this mission, although it will still be replaced.  On "Sally's" first mission, everything seemed to go well but when it returned the camera had run out of battery.  This was odd since the battery we used was most definitely fresh.  The camera did not seem to respond well to new batteries either, so we flagged it for later investigation and switched to a new camera.  Finally, "Sally" flew a successful flight and collected what looks like it will be a complete set of pictures of the forest canopy.

Feb 20 2012

Week of 2/13/2012: Flying the hexakoptors and surveying in Herbert Run

This week Stephen and I finally got to fly the hexakoptors.  It did not take long for us to realize that it is rather difficult to learn to fly them.  We will be practicing on flight simulators before we take the hexakoptors out again.

During the weekend, Andrew and I went to Herbert Run and surveyed the area to make a grid.  We accomplished to get a fourth of all of the points done!  Hopefully we can be as progressive in weeks to come.

Picture 1: Hexakoptor in flight.

 

Picture 2: Me after a day of surveying.

Feb 18 2012

New Undergrads learn the ropes of flying the Hexakopter

Shelby and I are the new mechE undergraduates for the Ecosynth project.  This past week we started learning the ropes to flying the hexakopters.  We started by bringing all three hexacopters to flight-readiness.  "Sally" was already operational, so we used her a s a model for repairing the other two. 

When we started, "Raven" needed new propellers as well as ribbon cables.  "Roflkopter" (I'm very fond of that name) needed its computer reassembled and mounted, as well as new propellers and the arms secured on.  Shelby and I did these repairs with little prior experience, so we were actually a bit surprised when both "Raven" and "Roflkopter" flew successfully.

By the time we finished, none of the three hexacopters were flight-ready any more.  The attached video is actually my one successful landing, the hexakopter controls take a lot of finesse and a lot of practice.  I managed to break a propeller on "Sally" by tipping over on landing, and Shelby managed to break "Roflkopter" 's landing gear with a hard landing.  "Raven" stopped working because of an issue with one of the motor controllers.  We took it back to the lab for analysis, but we called it a day and decided to reconvene next week.

Shelby and I are looking forward to working with these hexakopters and the Ecosynth team.