Wow! Has it really been 2 months since my last post?! Well I've been up to stuff. I really need to be up to stuff now because there needs to be a working demonstration for an event next month.
So I've been busy the past week trying to make some progress since basically gutting the rover a month ago to rewire it . In the process of rewiring, I realized the new steering controller needed to be wired so I started figuring out how to do that. While I was figuring that out, I started printing the rest of the suspension parts so the things that I was wiring had a place to go. I got about half of the parts made and started having printer issues. The parts all had some kind of flaw that had to be worked around or ignored. I didn't like that so I decided to outsource all of the parts to www.shapeways.com after doing a sample run of their services.
You can see in the photo on the left, my misshapen part compared to the part I got from Shapeways and then the photo on the right is of the 2 parts I ordered. So needless to say, after I saw the quality of their parts, I immediately ordered the rest of the suspension parts. They should be here in a couple of weeks. So while I'm waiting for that, I started working with the parts that I do have.
I plugged in 5 servos to the Pololu servo controller and then plugged in my 7.6v LiPo battery. The fact that my servos are only designed for 6 volts at most suddenly dawned on me as one of the more expensive metal geared high torque ones started to smoke. Not a pleasant little puff of smoke but a rolling black cloud that smelled a bit like burning tires. Just a few seconds was enough to leave a nasty smell in the shop for a day or so. Here is a photo of the damage.
So with that servo now liberated of magic smoke, I grabbed my trusty power supply and set it for a more friendly 5 volts (something I should have done to begin with) and plugged it in to the Pololu servo controller. I then worked out some quick code for manually operating the part of the drive system that I had left. Everything seemed to work. Then we went to the hobby store to get more metal geared high torque servos and was informed that these might not be powerful enough for what we want them to do. Since I hadn't actually tried them with any weight on them, I really couldn't argue so we went home empty handed and set up a test of the steering with about a half a pound of batteries on it. Since last we weighed the rover, it was about 3 pounds, we divided 3 by 6 and got .5 pounds for each wheel.
Here is that test:
It seems like it should work. Carpet might be another story but with only a month before a demonstration, we decided to go back and buy the rest of the servos that we needed to finish the new suspension. Now we wait for the Shapeways parts to come in.
In the mean time, I need to finish the code for the rest of the servos, fix that wobbly wheel, and figure out how to fit everything back into the body. And also do some more research on these next couple of items.
This website gave me a great idea for another sensor on the rover. With this site and another camera with their infrared filter on it, the rover would be able to take pictures of plants and tell how well they are growing. Kind of beats just sampling rocks with a metal detector.
While searching for a way to have an arduino send back images from another camera, I came across this nifty little device used for multi-camera FPV (first person video) systems.
Since this little switch can handle 3 cameras, I figure I could have the main mast camera, the IR camera somewhere on the rover, and a hazard camera on the front. This could be a great little addition. I just need to find out if all 3 cameras will have power to them all of the time or not. If they do, I'll need to ditch the idea or work out a power switch for them.
And then lastly, this little 5 Volt 2.5 Amp voltage regulator that could replace the heavy relays that I currently have for switching between batteries.
These say they can be enabled or disabled with a high or low signal but it's not very clear whether that means the output can be turned on and off or just the regulating part can be turned on and off. I'll need to look more into this.
So that's about it for now. I'll try and post more now that I have a bit of a deadline. Some part of the rover should be operational again by the end of next month so that means I should have plenty to write about. So stay tuned and have fun out there!
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