pic: Vex 2 Wheel Balancing Robot



This robot was part of the “Star Wars: Where Science Meets Imagination” exhibit at the Boston Museum Of Science.

There was all these cool Star Wars displays, (a bunch of them on robots, including fully programmable R2-D2s, ala Mindstorm RCX) and smack in the middle was this. I spent 20 minutes playing with it.

I wanted to be the first (that I knew of) to make a balancing Vex bot, but I guess I got beat to the punch.

So, how many components do you recognize on this bot from their frequent “CD-age”?

I see 3. :slight_smile:

well remember this thread… http://www.chiefdelphi.com/forums/showthread.php?t=40920

now i don’t need to post pictures of what i was working on because tom already did it. :wink:

Greg, first off, that’s awesome. I would love to see some video of it in action, hint hint.
From the picture I would say that you are using several non-standard Vex components. I can see the motor is not standard, the motor controller looks custom. I can see what looks like 4 analog inputs from sensors of some sort and one interrupt input from what I am guessing is a digital encoder.

Care to elaborate on how you achieved this? :slight_smile:

WE NEED DETAILS!!! :smiley:

It looks like the guts of the balancing comes from the accelerometer (from the 2005 KOP :slight_smile: ), gyro, and encoder.

I remember seeing the control algorithm for this kind of bot on some site. It needed 4 inputs… Angular position (found initially with accelerometer and force of gravity, then ntegrated from gyro), angular rate of change (reading from the gyro), linear position (encoders), and linear rate (derivative of position).

The stuff on top of the Vex controller was for a buzzer, and driving a backlit switch. There was a small servo amplifier on the other side.

Wow, thanks again Tom! Just like with the Kiwi Vex, you helped out tremendously.
(Now, if we can just see the code :rolleyes: )

well I asked if i could share the code but unfortunatly the answer was no. If you are interested in balancing code i would take a look here http://www.tlb.org/scooter.html

I have some other pictures that i can post later though.

Thanks for the reply and explanation. I understand the desire to not publicize the code, no problem.
More than that, thanks for the link. The information found there is really helpful and will go a long way in helping me do similar development! :smiley:

Now, FEED us PICTURES!!! Please :wink:

Hahah Tom I saw this before I left for boot camp. Not on subject, but weren’t the other exhibits awesome? I got a picture of every one of them, and pictures of me with Han’s clothes. Oh yeah, and a picture of me with one of the ForceFX sabers. That was a good day.

Can the two wheels spin independently? It looks like they are coupled.

it is one axle so they both move the same. These were just built as demo units to show how balancing works so independent wheel control (like the Segway) was not necessary.

As for the pics i need to get them off my work computer. maybe tomorrow

you ask and you shall receive.

http://robotphotos.org/v/members/first/Greg+Needel/vex/balance/?g2_statusId=x7d5be4d4&g2_navId=x73ef092f

also to give credit where credit is due. The original design used an IFI min controller and was build by Benge Ambrogi. That design was later changed to vex by Kristen Kelso. Then the final design was done by myself and another deka employee.

remember folks design is an iterative process.

I got a chance to play with this thing at Star Wars exhibit the last time I was in Boston. Very cool.

If you’re in the area, I would encourage you all to check it out. I believe it ends on Sunday.

Now all someone has to do is make one that works with the VEX motors. Heck, even doing it with the more powerful robovation motors would be a challenge.