View Full Version : [Project] Aphid

12-06-2009, 10:21 PM
They say imitation is the best form of flattery...so consider this a robot inspired by Zenta's T-Hex (http://forums.trossenrobotics.com/showthread.php?t=3712). Ok...so its not even remotely close, but I had a few hours and thought I would see what I could do with the bioloid that has been sitting here since last summer.

I don't think I quite understood how big T-hex must be. This quad started out as a hexipod, until I realized the back 4 legs were way too close together. The good news is that it works as a quad. I'll get a hex version up and running after I get this one where I want it.

This is my first self designed bioloid based robot. I do feel that while the kit does go a long way towards removing a lot of difficulties, and makes it possible to make a working robot in just a few hours, as with any bracket system, it takes away a lot of the creativity involved. I found myself making definitions that were largely shaped by the kit, in a more invasive way than I am used to.

The CM-5 is very compact, and all encompassing. This makes it so that you don't really need a lot of space in order to hold your batteries and electronics and can have a very compact robot. I'll try to play with this a bit more in the hex version.

The feet are wheels set on continuous rotation servos. It can stand on the edge of the wheels and roll around as a rover, and then swivel the wheels under for walking.

Finally the head on this guy is strictly bioloid, and butt ugly...I wanted to wait until I saw what the body would look like before I designed a head I could be proud of. It has the bioloid sensor unit on it, and can pan and tilt.

In anycase, I'm not thrilled with what I have so far, but I'm hoping I can get the ugly out of it in short order.



12-07-2009, 05:12 AM
interesting feet/wheels, keep it up :D

12-15-2009, 01:27 AM
So its been about a week, and I almost gave up on aphid...almost. I still haven't done much to improve the looks of this bot, but I did get some figuring done. Most notably with the help of Rebel's shadow cat. (http://forums.trossenrobotics.com/showthread.php?t=3695) Most notably I am now using the Droids xbee serial board to connect the CM-5 to the computer.

Oh yeah...and I am planning to add rubber posts to the feet so that it isn't sliding on the floor so much.

I'll try to post a better video this weekend.



12-15-2009, 04:41 AM
very nice, but i would like to suggest that you move the body a bit more up when in 'walk mode', those 'knee's' might aswell be used :wink: and when its higher above the ground you could make bigger steps (given, it could also fall further down)

Keep it up, very interesting! also, it begs for skate anims! (though idk if that would be possible considering its not 'free' wheels)

12-16-2009, 12:23 PM
I was hoping to include a picture describing this, but...I just haven't had a spare second.

Imaging you have rollerskates on. so instead of walking on the wheels, you twist your ankles so that you are walking on the sides of your feet. Bowing your legs out to the sides. That is the closest analagy to how Aphid currently walks. Lifting the body higher extends the leg, but also pushes the feet closer to the center line of the body. This limits the radius of each step, and thus reduces step size. Aphid can actually take bigger steps by lowering the body, and therefor walks faster. I hope this helps...I know it isn't the clearest description...and a picture would make it clear in a hurry.

On another note, my CM-5 now no longer works at all unless it is plugged in. I checked the fuse for continuity, and it tested positive. I'm thinking there must be a short somewhere else, unless there is something that I am missing.

Any ideas?


12-16-2009, 02:48 PM
DB, I saw a robot that moved using a method pretty close to what you are talking about. It had wheels at the end of the legs and rather than motorizing the wheels it would weave the legs in and out to provide forward locomotion.

As for the CM5 problem, what do you mean it doesn't work except for when plugged in?

12-16-2009, 03:27 PM
YouTube- Quadruped Robot - Gait Motion (http://www.youtube.com/user/painrose#p/a/u/0/MFgePgQ73Ws)

YouTube- hybrid walking robot

To say these are inspirational would be the understatement of the century. I've been looking at these two bots for a long time. I may add another degree of freedom after I play with aphid for a bit, and get to the point where I'm relatively happy. I'm sort of trying to limit myself at this point.

As for the CM-5 not working if its not plugged in...If I don't provide it with an external 12 volts via the adaptor it does not work. The battery reads 11.5 volts...so its not a dead battery it even tries to go through the recharge cycle, and says that it is charged. But if you disconnect the external powersupply it looses power and won't turn on at all.


12-17-2009, 02:34 PM
You blew the fuse in your CM-5.

12-17-2009, 03:01 PM
I wish it was the fuse...already tested it (for continuity), and swapped it out. luckily I have a second cm-5...so I switched over the motions and now have it running right...I looked over the old CM-5 and there are no scorch marks on it or anything...what a bummer!


12-17-2009, 04:51 PM
That means its time for you to pony up for one of them thar fancy arbotix controllers!

12-17-2009, 06:29 PM
an arbotix is on my list...I'm just not sure I can figure out how to get it to work. This is one area in which I have a major short coming. I don't know any "real" programming languages. i do all of my programming in MAX right now.

In terms of controlling Ax-12s...i'm struggling with generating valid check sums...I should get an example of a working command, and then I'll give figuring it out a try.


12-17-2009, 07:31 PM
Here's a sample command, to set the servo with ID = 1 to position 511:

255 255 1 5 3 30 255 1 (216)

The last byte (in brackets) is the checksum, 216. It is computed by ignoring the first two 255's, and adding together the remaining bytes of the command:

1 + 5 + 3 + 30 + 255 + 1 = 295

Next we turn it back into an 8-bit number:

295 bitAnd 255 = 39

Finally, you have to flip all the bits, which on a computer is done using XOR:

39 bitXor with 255 = 216

So the checksum is 216.

- Jon

12-17-2009, 07:41 PM
Here's a hex and binary example

12-23-2009, 09:07 PM
Had some time...threw this together. I am still trying to figure out ways to make this bot better looking...for one I'm going to mount short posts on the bottoms of the wheels so that when it is in walk mode it stands a bit taller. I also want to give it a "face" of sorts.

Oh well...guess I've got another week of holiday break.



12-23-2009, 10:14 PM
That's pretty darn cool. I like your idea of adding some kind of foot on the wheels. I was thinking that same thing while watching the video.

12-27-2009, 07:00 PM
Here are some pics of the posts that I mounted on the bottoms of Aphids wheel/feet.

They lift her up just under an inch. While she is a lot more tippy now, its not as bad as I thought.




01-10-2010, 08:32 PM
I really like Aphid, nice work!