Busy Summer

The past couple of months have been pretty busy for Inspiration. 2 almost back to back weekends demonstrating as JPL Solar System Ambassadors at the Science Museum of Minnesota and then at a YMCA in Wisconsin. Very fun and exciting opportunities! I even decided to start letting kids drive Inspiration around on the table! Really scary at first but most of the kids surprised me with how quickly they figured out the controls and understood how the commands were being processed by the micro controller. A few others seemed hell bent on destroying it. For the most part, though, it was pretty fun and I really enjoyed watching kids light up when they recognized how the code worked that was coming up on the screen while they sent commands to the rover.

Here's some pics from those events. If you recognize your child (or yourself) and would like the picture removed or credit for the pic, just let me know.

This girl was amazing! She totally understood what was going on and probably knows more about code than I do.
She lit up when she saw the code and immediately grabbed her friend who she started talking in Spanish to about it.
I was super impressed and would love to know where this kid goes in life.

This was one of the first kids that I let drive. 3 years of  really hard work in the hands of a young boy. I may look calm,
but inside I was freaking out. He did a great job though and my nervousness quickly went away when it only took him
a few button presses to figure it out. I would love to let more kids like him drive.

Inspiration meets Curiosity. Thanks to the JPL Spacecraft 3D app, you can do augmented reality with JPL spacecraft. 

Once the demonstrations were done, I decided to look into how the battery was being charged by the solar panel. I quickly realized that it wasn't. The solar panel is capable of about 200 to 300 mAhs. Just sitting there, the rover draws about 200. So the solar panel really wasn't doing much. The nice thing is though, that Inspiration can sit for about 4 hours before dying.

I decided to go back to the 2 battery system where the rover drives on one battery while charging the other and then switching as one battery is drained and the other is charged. Theoretically it should keep Inspiration running as long as there are sunny days. However, I found out the code for such a change over can be tricky. Also, the discharging battery drains faster than the other can be charged so there ultimately the rover would be dead after about 24 hours.

Here are some tests that I did while at work a few weeks ago. I was trying to get the code right and also collect data on how long it takes to charge and discharge.

This was the setup I had going outside of work and I monitored the battery voltages from my desk

Unfortunately the sun wasn't out all week so I had improvise with this setup under my desk.

First test showed one battery powering the Arduino and Xbee shield and the other being charged.

This test showed what happened in my code when the 2 batteries became equal in voltage.

This was a successful test of the batteries charging and discharging. 

After these tests I decided redesign the power distribution system and get a few new things to help with better charging capabilities.

A new relay. This relay uses a lot less power to actuate the switches and each relay can switch 2 circuits at once. This should work well for the 2 battery system.

To manage the power system I decided to get an "Arduino" Nano V3. This little guy will stay on all the time and be able to monitor the batteries, solar panel, and communications so that it can properly distribute power. It will be running the code for charging and discharging. It will also be able to turn off the rover at night or in low power situations. It sips power so having it on all night shouldn't be a problem. 

A few other changes I made were to move the camera up front and change how the metal detector arm works. Here is the final product of that change:

After all of this weight got moved to the front, I needed a counter weight in the back so I printed a battery holder for the back. I think it actually makes the rover look better now.

Now the current situation is that Inspiration will be traveling with us to Tucson for Spacefest VIII. So once I got all of the changes made, I had to make a box and ship it.

Inspiration in its "Launch" configuration

Made a foamcore box to put it in for shipping.

And the final package complete with duck tape handles and ready to be stuffed in another box and shipped.

That's about it so far. I will try to post more after Spacefest and show you guys what it was like. If you've never been, I highly recommend it! Stay tuned and have fun!