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Mar 28 2012

Forest Fire Videos Captured with a Hexakopter

Here are links to two videos we collected of the forest fire we flew in early March in New Jersery.  Stephen had posted previously, post here, about our experiences getting the payload to fly on the Hexakopter, a repeat of similar work from last year.

Taking video was an afterthought for the project so we only had an SD4000 on hand for filming.  I think the video quality would have been a lot better if we had the GoPro.  Despite the wiggle and bluriness of the video, it is still possible to see the smoke lines set by the fire managers (see images at left) and there are places in the afternoon video where I think you can even see fire.  Note that these videos were taken pointing about due west, so I believe the shots from later in the day appear darker due to exposure compensation.

Video from about 12:45 - 12:55 local time: http://youtu.be/q3S3V3212bo?hd=1

Video from about 15:45 - 15:55 local time: http://youtu.be/GQHh2LX_ad8?hd=1

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.

Aug 03 2011

Pentax WG-1 GPS camera–too slow for scanning

I loved the Pentax WG-1 GPS camera when it first arrived.  It looked cool, had a non-extending lens, and offered the potential for GPS tagging our photos during flight – a feature that could be very time-saving for reconstructions.

But out of the box I quickly noted some major drawbacks.  The first was that the GPS only updates every 15 seconds.  At the average speed of 5 m/s of a Hexakopter, that meant that GPS logs would be something like 75m apart!  The unit also has a slower continuous shooting mode than the SD4000, about 1 fps.  The biggest drawback by far though was the lag, which I can only assume is a memory write lag.

I set up the camera to the maximum image quality settings, in continuous shooting mode, and with 15 second GPS refresh.  I was using a brand new Sandisk Extreme 16GB memory card, which would provide professional grade write speeds.  I strapped down the shutter button by lightly taping a plastic nut over the button and wrapping the unit with a velcro strap, just like we do with the SD4000s.  The Pentax WG-1 would take a continuous stream of about 30 photos then stop.  It would show the ‘number of images remaining’ counting down and just hung out.  After sometimes 10-15 seconds it would then resume taking photos continuously, but then repeat the same thing after another 30 photos.  The camera was not taking photos for 10-15 seconds while in continuous shooting mode.  At a flying speed of 5 m/s that means that for 50-75 meters in the air, no pictures would be taken!

I repeated this test with increasingly lower camera settings until I got down to the lowest possible settings of maximum compression and 640x480 resolution.  This time the camera took lots more photos  (~100 or so) but still had a long lag of no photos.

It was this that finally made us decide to send the Pentax WG-1 back.

Based on my research this GPS camera has the fastest GPS refresh time of any other point and shoot style camera, but the continuous shooting ‘lag’ was a deal breaker.

Jul 29 2011

Multirotors on the Colbert Report

Check out multirotors on the Colbert Report!!!  The clip starts at about 15 minutes into the program.

The researcher, Missy Cummings Associate Professor from MIT, is developing better human multirotor interfaces to help people steer the units using only a smart phone, which makes me wonder how different it is from the Parrot AR.Drone.



Seeing this video reminded me of something I noticed when flying the Hexakopters on campus with Tom Allnutt last week, see his post here.  Many people stopped and asked, ‘What is that?’, as usual, while we were out practicing in the Quad at UMBC.  But almost everyone asked if we had put a camera on it, as if that was the obvious thing to do with such a cool device.  I explained to them our research and that we do usually fly with cameras and thought to myself that something is different now then when we were practicing last year.  In September 2010 when people asked us what we were doing they never asked if we were putting cameras on the devices and thought it was an odd thing to do when we told them about our work.  Now it seems that the practice is even expected.  I hope this signals a shift in perception about autonomous vehicles as useful tools for research and for recreational aerial photography and not just greater public awareness about the other uses of such devices.

UPDATE: I've been thinking about this post and in all fairness, the researcher is discussing the use of multirotors by the armed forces.  I posted for the sake of noting the signifcance of the devices in pop-culture.

Jul 18 2011

XBees Again

I think I have fixed the XBees, again, maybe…

I wanted to get our tablet laptop up and running again as a Hexakopter flying machine for the field – especially since I got the new Pentax WG-1 GPS camera in the mail today (I’ll post on that soon).  This laptop had already been running Mikrokopter-Tool v1.74a, allowing us to do 3D waypoint runs, but the XBees were not functioning at all.  I also had it in my head to install a SSD hard drive in this old laptop to give it a new lease on life – what better opportunity to try a fresh setup! 

A quick note to anyone that has found their way here with their own XBee woes, we are using XBee Pro DigiMesh 900 modules.  This post discusses the (hopefully) successful configuration of a pair of XBee Pro 900’s each mounted on an Xbee Explorer USB.  In a previous post, Xbee Solutions?, I suggested that it is necessary to have an Xbee Explorer Regulated on the MK end, but it seems that may not be necessary based on the results described below.

I got all the standard drivers and software installed and running (XCTU and  UART drivers) and plugged in the suspect Xbees.  Windows 7 said it correctly installed the new hardware, but when I opened up MikroKopter Tool I could not get any XBee communication. AAAAAAAH!

Back to the internet, I found this long thread about Xbee problems that offered promise: http://forum.mikrokopter.de/topic-21969.html

Taking from the thread, I set up two XBees on the same machine in two instances of XCTU to be able to effectively range test and compare parameters. Why had I never thought of that!? I read the modem configurations from each unit – mostly noting anything that was other than the default and confirming the baud rates were set correctly.  I quickly noted that the Modem VID numbers were different and read from the help dialog: “Only radio modems with matching VIDs can communicate with each other.”  One XBee was set to the default and another was set to a specific number.  I didn’t remember making this change but decided to set them both to the same number.  The range test was now working perfectly (see post picture).  Back in Mikrokopter Tool I was back in business with wireless telemetry, but I still couldn’t transfer waypoints.  I kept getting that ‘Communication Timeout’ error.

I tried another suggestion from this  post  in the same thread and manually adjusted the Destination Addressing fields on each unit.  I noted the high and low serial numbers for each unit (SL and SH) and manually configured the  high and low destination addresses to point at each other: XBee1 DL = XBee2SL, XBee1DH = XBee2SH, and vice-versa.

I flashed these settings, booted up MikroKopter Tool and was wirelessly transferring waypoints and receiving telemetry with no problems.

Of course, now we just have to see if it’s actually going to work in the field!

Next up: playing with the GPS camera!

Jul 15 2011

First Altitude Controlled Hexakopter Flight!!!


This past week I've been working on flashing the new firmware to fly altitude controlled waypoints. As it turns out there was no need for the newest hardware to use the latest firmware (FC 2.1ME, BL 2.0 required). After working out some compatibility issues with the old version of MKtools, I finally was able to connect to the Hexakopter. Today we were able to do a flight test, check out the video for yourself (best in full screen hd).

Next week I plan to flash the new firmware on to the other 2 remaining Hexakopters.


                                                                                        Why are you reading this watch the video!

Mar 05 2011

Field Day with the 485 Class

We had a great field day with the GES 485 class on Saturday flying the Hexakopter at the Herbert Run site and developing field work and 'ground-synthing' techniques.

The weather was actually quite good for a data collection.  The sky was overcast and there was no wind, meaning that the Hexakopter was able to stay on track and the light was relatively diffuse so there are few shadows in the images.  I gave a large set of about 2000 photos to Photoscan for processing on Saturday afternoon and it is still running.  This is a great software, but I don't yet have enough of my own benchmarking data with large sets to really test out how it is going to work. I hope the point cloud looks good!

Regarding our Xbee testing, I used the MKUSB to upload waypoints, but then discovered that when I power down and then power back up to swap out the battery and plug in the wireless Xbee module I cannot read waypoints from the MK, or they are not stored on board.  But, I was able to upload waypoints wirelessly with the new Xbee configuration and the real-time telemetry communication during the flight was OK.  At least the current setup is no worse than what we had before.  More to come.

Mar 02 2011

Xbee Solutions?

Is the solution to our Xbee problems to not use them at all?

You may recall several posts and rants about our problems with Xbees, http://ecotope.org/ecosynth/blog/?tag=/XBee, and we have been actively looking for a solution.  The picture at left shows a potential new system for transferring data from the field computer to the Hexakopter on the ground and then in the air.  In this picture is the Mikrokopter MKUSB module that is used for hard-wired USB data communication between the Hexakopter and the Mikrokopter tool software; a new Sparkfun USB Explorer Regulated board; 2 Digikey Xbee Pro 900 modules; and a Sparkfun Xbee Explorer USB module.

The plan is to use the MKUSB module to upload waypoints and control settings to the Hexa prior to flight, then pop on the Xbee wireless configuration for spotty telemetry during flight.

Our problem for months now has been very unpredictable performance with the Xbees for wireless telemetry communication.  The set up was: 2 Xbee Pro 900’s both mounted to Sparkfun Xbee Explorer USB modules.  One Explorer USB was set up for USB communication with the laptop (the module shown at right in the image) and one Explorer USB had a ribbon cable soldered to it for plugging into the Hexa (image not shown).  At first, this seemed to work OK, but for some very odd reason, this set up started failing, to the point where it was impossible to wirelessly upload waypoints to the Hexa from the laptop within just a few feet of the unit.  I do not want to think about the countless hours wasted on this.

This new setup aims to 1) circumvent the need to us Xbees for mission critical steps (waypoint and configuration upload) and 2) use a different hardware configuration to attempt to re-establish successful wireless telemetry communication using Xbees during flight.

We will use the MKUSB in the field to transmit waypoints and configuration settings to the Hexa via wired communication and then use the Sparkfun / Digikey configuration shown above for getting what wireless telemetry data we can during flight (with the assumption that the Xbees will still fail or be spotty).  Sparkfun recommends this configuration over the use of 2 Explorer USB modules and we are not entirely sure why we have the configuration that we have been using.

With a leaf-off flight planned for the UMBC Herbert Run site on Saturday, I hope to have some positive results to report next week!

Feb 25 2011

Photoscan is awesome!

Agisoft’s Photoscansoftware is simply amazing!

The picture at left is an orthorectified photo mosaic over our Knoll research site on the UMBC campus generated by Photoscan automatically using only input photos that I took with the Hexakopter.  For reference, each Hexakopter photo covered less than a 10th of the area observed in this scene. 

An orthophoto is a photo that has been mathematically distorted based on the differences in elevation of the scene so that everything appears ‘flat’, or it appears that the camera was right above each point in the photo.

Photoscan uses similar computer vision technology that Bundler and Photosynth use to automatically recreate the 3D structure of a scene from only photos.

The professional version of the software also makes it very easy to georeference the scene to a geographic coordinate system, making it possible to easily view in a GIS software … or in Google Earth.

Here is a link to a Google Earth image file that Photoscan generated from our photo set, enjoy (35MB kmz file)! 

I am working on getting some 3D output to Google Earth next.