Excavation Video with Deformable Terrain

[Nader Samid]

I'm providing a link to a video here showing two rovers (similar design to the bucket loader provided on the digital spaces website) performing an excavation task in lunar terrain. The excavators each have their own "intelligence", and make decisions on how and where to dig based on sensory interaction with the environment. The goal of this task is for the excavators to dig a 5m X 5m area which ends up being the region that is roughly dug out by the end of the video. Presently, conservation of mass is not incorporated in the deformable terrain model, so only regolith removal is observed. Over the next couple weeks I'm hoping to be able to correctly implement mass conservation to get the digging to look much more natural and realistic. Still, I think it's getting there. The video is a composite of clips taken at different time points in the dig. The link to the video is http://sr.utias.utoronto.ca/~nab/Excavation1.wmv

Nader Abu El Samid
MASc Candidate
Institute for Aerospace Studies
University of Toronto
Toronto, Canada

[PeterNewman]

Very interesting! What sensory inputs is it using?

[Nader Samid]

The inputs for this controller include blade height relative to the ground, blade load, front obstacle detection, separation distance from the nearest robot, heading from the nearest robot, rover tilt, ground depth sensing relative to goal depth, and rover stuck situations. To obtain blade height, front obstacle detection, separation  distance, tilt and heading information, I use global position and orientation data which is available in the software. For ground height info, I monitor the global height of the tiles which make up the surface of the work area at appropriate times. For blade load, force is calculated on the blade using the Balovnev force model.

[PeterNewman]

We've uploaded a mirror of that movie to http://www.digitalspaces.net/projects/community/nadersamid/Excavation1.wmv , so people can grab it from there as well. I know it's been forwarded to a few people, outside the forum.

[Nader Samid]

I've made some progress on the simulation since my last update, and just thought I would share a new video. It's sped up a bit to show excavation of a hole using our controller. The new simulation now also incorporates conservation of mass to realistically show ground deformation and mound formation. The link is

http://sr.utias.utoronto.ca/~nab/2RovSim_Version2.wmv (http://sr.utias.utoronto.ca/~nab/2RovSim_Version2.wmv)

Any feedback you may have is appreciated.

[PeterNewman]

That is really great to watch in action.

Are you still using a grid of boxes under the rovers, with the changing visual mesh over the top?

[Nader Samid]

Yes, the grid boxes are being used in combination with the visual mesh. I tried for a while to get the terrain volume to be one continuous shape with a deformable surface, but couldn't quite get it to work. Maybe you could help provide more insight into how this can be done. The current method still does give pretty good results, but since there are only so many shapes that I can create in a world (around 2300 shapes appears to be the limit I'm encountering), the work area can only be so large without compromising on resolution of the boxes that make up the terrain. Still the work areas that are possible with decent resolution allow me to test up to 5 excavators in a multi-robot simulation, which meets our needs.

[PeterNewman]

We've uploaded a mirror of this movie to http://www.digitalspaces.net/projects/community/nadersamid/2RovSim_Version2.wmv (http://www.digitalspaces.net/projects/community/nadersamid/2RovSim_Version2.wmv).

Is it ok for us to use these videos in our promotions of what can be done with the Digital Spaces engine?

[Nader Samid]

I've actually just been told by my professor that I have to put our University and our sponsor's logo on the video first. I'll try having that ready for you by tomorrow. I have a newer version of the excavation video as well with less aggressive digging that produces a smoother contour on the final dug out work area.

[Nader Samid]

I have a link to a new video with the smoother final digging area. I've adjusted the blade height so that the rover digs less aggressively than was seen before, reflecting more realistically how an expert operator would control such a machine. I'm just waiting on getting some final permissions regarding the use of logos, etc., so would it be possible to hold off for a couple of days before going ahead? When that happens, I'm not sure if you want to put the other videos that I've posted up there as well, showing the development phases, considering that this current video shows what we are trying to do the best. Also, as I progress to further improve the simulation, by having more rovers, or by utilizing other excavator designs with other controllers that we develop in our lab, I was wondering if it would be ok to put a link up directing people to our site to see additional videos (Right now the videos are not posted there, but perhaps you could include a link to the University of Toronto Institute for Aerospace Studies for people to see further information about what we do in our lab). The website is : http://sr.utias.utoronto.ca/ (http://sr.utias.utoronto.ca/)

[PeterNewman]

We can certainly wait until the videos are ready and clear on your end. We will probably use the most recent video(s) as they will show the simulation best. And we are quite happy to include a link to your site when showing the videos. We'd appreciate it if you also linked back to the Digital Spaces site ( http://www.digitalspaces.net/ ) as well.

[Nader Samid]

Hi,

Here's the link to the final polished video. It's http://sr.utias.utoronto.ca/~nab/2Rovers_March3.avi (http://sr.utias.utoronto.ca/~nab/2Rovers_March3.avi)

A DivX codec is required to see the video, which can be found at http://www.divx.com/divx/windows/ (http://www.divx.com/divx/windows/)

You don't have to provide the weblink I posted earlier, because we're putting up a new site, with the link mentioned in the credits of this video. As of now, the link provided in the video is not active, but should be up soon. When it is up, we'll put a www.digitalspaces.net link there.

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