Author Topic: Update on MicroRaptor progress  (Read 4066 times)

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Offline JonHylandsTopic starter

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Update on MicroRaptor progress
« on: December 24, 2006, 12:35:09 PM »
In case you guys aren't following, I've made a bunch of blog posts, including several that show progress on a CAD model I have built for the next robot I am building, MicroRaptor.

http://www.huv.com/blog

I expect to start building the robot itself once I get my hands on the Bioloid kit, hopefully sometime in January. In the meantime, I'm cranking away on design work and software.

Interesting book I just finished reading - "On Intelligence" by Jeff Hawkins. An excellent read - I highly recommend it to anyone who likes to think about AI.

- Jon

Offline Admin

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Re: Update on MicroRaptor progress
« Reply #1 on: December 24, 2006, 06:16:50 PM »
potential problems I see with your CAD . . . hey, im a mechanical engineer its instinctual . . .  :P

http://www.huv.com/blog/uploaded_images/MicroRaptor-02-734314.JPG

the head looks heavy, and the servo that drives the head will not only possibly have torque issues, but also unneccessarily drain lots of power to support the head.

considered using a worm gear instead? or at least some kind of spring force to support the weight?

as for the tail, I am assuming its for balance . . . did your moment arm balancing equations yet?  :P

otherwise the design looks well thought out and stable . . .

Offline JonHylandsTopic starter

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Re: Update on MicroRaptor progress
« Reply #2 on: December 24, 2006, 07:59:51 PM »
Thanks for the feedback Admin... Being a software guy, I don't always consider everything...

The servos have approximately 200 oz-in of torque, so I don't suspect that will be a big issue.

The leg servos (and specifically the ankles) are going to have a lot more weight on them than the neck servos - I actually wasn't very concerned about the neck.

The tail is to help with balance while walking, yes. I hvaen't done any calculations because (a) I wouldn't have the slightest idea how, and (b) I haven't built the thing yet, nor do I have the kit, so I don't know what all this stuff weighs. I was planning on building and weighing the tail to counteract the weight of the cameras, whatever that ends up being.

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Re: Update on MicroRaptor progress
« Reply #3 on: December 24, 2006, 08:13:48 PM »
i guess the experimental way will work . . . but if you want to calculate beforehand . . .

its basically a moment arm balancing equation
http://www.societyofrobots.com/mechanics_statics.shtml#momentbalancing

weight_neck * mass_length_neck = weight_tail * mass_length_tail

where horizontal length is from the pivot point (location of foot on ground, not leg joint) to center of mass of the neck. you just want that equation to balance. ehhh that sounds kinda confusing . . . lemme know if it is . . .

basically it means that if you have a long tail, put the weight at the furthest point possible - results in a lighter tail, yet more effective.

Offline JonHylandsTopic starter

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Re: Update on MicroRaptor progress
« Reply #4 on: December 24, 2006, 08:16:25 PM »
Yeah, I kind of assumed it was something like that. The two spacers on the tail will be machined from whatever material makes sense to get the weight I need.

Like I said, though, it will have to wait until I actually get the kit...

- Jon

Offline polar bear6

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Re: Update on MicroRaptor progress
« Reply #5 on: December 26, 2006, 08:30:11 PM »
I just have to say that this was amazing.
now i know I'm not a super roboticist like the admin and you ( i am thrilled over that i can get my boe bot to move forward and turn ;D), but why do you use 2 cameras, is this for some obvious reason you discover after you have completed the Boe Bot, or is it just for the looks?
I saw you super roboticist talk about weight might being a problem, i thought that maybe you could only use one camera instead of two.

Offline JonHylandsTopic starter

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Re: Update on MicroRaptor progress
« Reply #6 on: December 26, 2006, 08:52:27 PM »
I am planning on using two cameras to do stereo vision. This will allow the robot to determine the distance to objects that are relatively close. More specifically, I plan to have the cameras mounted with a mechanism that allows them to be turned inwards towards each other, in much the same way our eyes rotate in as an object (like your finger) moves towards your face.

The important part of that feature is not for determining distance. What it allows me to do is discern an object that is close to the robot (its point of interest) and ignore the background clutter more easily.

What I have built so far isn't all that amazing - its just a CAD model right now. There's a lot of design work in it, but I wouldn't call it amazing until after I have some video of it walking and "seeing"...

- Jon

 


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