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.




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 16 2012

Updates: Hexakopters, Quad Arducopter and Octocopter.

Now that the hexakopters are basically complete (one has a programming error that we are currently working on), Stephen and I decided to work with our other projects: quad arducopter and octocopter.

The quad arducopter (4 blades) is working.  We spent a few days familiarizing ourselves with the parts of the copter using the arducopter wiki (http://code.google.com/p/arducopter/wiki/ArduCopter).  The electronic speed controller (ECS) still needs to be calibrated, but it the copter is connecting to the computer and seems to be in working order.  We have started the parts list so that we can move forward.

The octocopter (8 blades) is still in the supply obtaining phase.  We have already placed our order for the necessary parts to construct the copter.  Within a few weeks we shall have those supplies and can commence the construction!  The objective of the octocopter is to run the trials the hexakopters are currently doing, but more efficiently.  It is also hoped that we can use the octocopters to expand the scanning area. 

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.

Jul 29 2011

Introducing "Vanga"

I work for REBIOMA - a joint project of UC Berkeley's Kremen Lab and the Wildlife Conservation Society, Madagascar. We develop and apply spatial tools for biodiversity conservation in Madagascar. For example, we work with a wide array of individuals and institutions to publish high-quality biodiversity occurrence data and species distribution models on our data portal - work that has helped to identify 4 million hectares of new protected areas.

Last week, I visited the Ecosynth team to build and practice flying what we're calling "Vanga" - a Hexacopter that we will take to Madagascar in late 2011 to map forest cover and forest disturbance in the Makira and Masoala protected areas. 

We're excited about the potential for low-cost, high-frequency forest monitoring in two and three dimensions. We will start by testing the capacity of the system for producing high-resolution 2D ortho-mosaics of selected field sites. We also hope to explore the 3D modeling capabilities - this has real potential for contributing to ongoing biomass measurements, and contributing to forest carbon inventories. Finally, we plan to evaluate the potential of this system as a tool to help communities adjacent to protected areas measure and monitor their forest resources.

May 23 2011

Geometry Matching for Coordinate Transform Computation Looks Promising

Our coordinate transform algorithm has given us encouraging output. By assuming that the camera and GPS data points all follow the same general geometry, we were able to interpolate and pick 100 points from both the camera and the GPS that should theoretically be in the same geometrical location. Using these 100 points, we used the least squares function and the Helmert coordinate transform algorithm to find the 7 unknown rotation, translation, and scaling parameters. We then used those parameters and the Helmert equations to transform our 100 camera points to match those of the GPS. Out data definitely appears similar in geometry, though the camera points are a bit off from the GPS: The average distance error is about 5.3 meters. This could potentially be corrected by picking a larger number of points from the splined data.

We used these parameters to also transform the point cloud, though oddly enough it transformed upside-down! Also, we are getting errors when the order of the camera list is not synchronized with the GPS. If we can synchronize the first Camera time with the first GPS data time, we could potentially reorganize the camera list so that it matches that of the GPS.

Though a bit more tweaking needs to be done to our code, this method of matching the data and GPS points looks very promising.

May 19 2011

End of Semester Summary

Hey everybody!
  As finals week draw to a close it looks like the forestry interns will have the time to get some much-needed field work done. Although it's coming close to the wire, or departure date, we're confident we can get our classifications and digitizing done within the next week. Here's little summary of what our contribution to the EcoSynth team has been over the past semester: Digitizing 25x25 field mapping done in previous semesters (February/March), Assisted with several Hexacopter flights (throughout), Surveyed remaining portion of the Knoll (April-present). The work that still needs to be accomplished includes completion of the survey in the Knoll by getting species and crown height measurements, and potentially creating a campus tree-identification guide. Additional related field work completed outside of the internship, and within the environmental mapping class( GES 485) is a complete, and digitized 25x75 meter survey subset into 5 meter grid cells, this survey included the positioning of every tree, large detritus items and stream profile. All of this collected data can hopefully be used to further calibrate the computer vision system, and can be used as a base for further research.

Extra Links: Using backlighting only from an IPhone, Grant Schindler developed this low budget (point cloud it seems) 3D scanning software. While it is nowhere near research grade equipment, He seems to have chosen using a non-natural lighting source to assist in 3d visualization, and for the Iphone it makes perfect sense to use the backlight adjacent to the front-facing camera.

Grant's page: http://www.cc.gatech.edu/~phlosoft/

May 07 2011

Links of the Moment

  • Krzysztof Bosak, who created the Pteryx UAV, is suggesting a photogrammetric aerial robotics contest.  Pteryx, Smartplanes, Cropcam, and several others are now hovering outside the market space associated with our fixed-wing work, waiting for the US and others to legalize their industry.
  • ArduCopter Mega, the unification of the Ardupilot navigation toolset with the quad/hexa/octocopter flight control code, is being released very soon
  • At the UW GRAIL lab: The maker of SiftGPU, Changchang Wu, has put together a multi-core bundle adjustment algorithm with available open software
  • At EPFL CV lab: