Team Ucalegon's ants

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peterwaller
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Re: My first ant was not a success: Onto the second!

Post by peterwaller »

It is always difficult to bend near the edge of the material you will find it easier to have the material say 2 inches by 4 inches then after you have bent it trim it to the size required.
tomchaps
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Re: My first ant was not a success: Onto the second!

Post by tomchaps »

Well, I wound up hacking lots of the polycarb off, and having to add little braces in the corners to keep it together. It's almost torn through by the wheel holes, too. Ah, well, a learning experience--and the local plastic store had a stack of about 15 small 8x10" sheets of 2mm and 3mm polycarb in their scarp rack, so I have some to practice with, I guess.

However, Robogames safety is Thursday! I am unlikely to have time to rebuild from scratch at this point. My big problem is the flipper. How the heck do people get that great range of motion into their flippers? The servo only has a 90 degree range of motion, so I'm using a linkage, but there's just so little room--the starting angle is really tiny at this point.

Here's a video--maybe I can extend the servo arm a bit? https://www.youtube.com/watch?v=60l5xgc ... e=youtu.be

What do people use for linkages? I'm testing with a bend paper clip, but I'm sure there's something better...
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UserFriendly
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Re: My first ant was not a success: Onto the second!

Post by UserFriendly »

Ideally, your servo arm goes parallel with your flipper. From the video, yours is the opposite, if you see what I mean.
You will get more movement from the flipper if it attaches nearer the flipper hinge.
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Shakey
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Re: My first ant was not a success: Onto the second!

Post by Shakey »

I made this graphic a while back that should help you understand the links and how to control it for more throw or speed:
Image
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tomchaps
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Re: My first ant was not a success: Onto the second!

Post by tomchaps »

Yeah, I decided last night to scrap the old chassis and start over. (Robogames safety check in one day! Eek!)

I did learn a lot about bending polycarb in the kitchen, though, and that I needed a bit more height to make the servo linkage feasible. I just started whacking away with my shears and bending over the edge of my cutting board, and it's actually much better than the first version. I cobbled together a servo horn extension, and am going to try to figure out the best linkage length tonight.

http://imgur.com/uDe7Gp2 for a photo. I can't get B and C parallel, but the angle will be MUCH better (i.e., less acute) than it was in the last model. I'll move the attachment point of the flipper farther up, so the B-to-C ration will be much higher.

I'm worried about self-righting, and the low torque at the beginning of the lift (due to the acute angle I'll start from) but we'll see.

Thanks for all the help...
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Shakey
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Re: My first ant was not a success: Onto the second!

Post by Shakey »

That flipper linkage is looking a lot more capable geometry wise. Also I think i spy a pink servo, I started using these as they have so much power that you can afford to have some inefficiency going and they'll still be more than happy. You should be alright torque wise for self righting.

It might be worth shortening B to just the servo arm then you can get the AC connection nice and close to the back of the bot with a long link bar (A). Looks like that'd give you the best angles in the setup. It's also at this point I think I should have picked a better naming scheme than just some letters in that diagram! :D
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tomchaps
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Re: My first ant was not a success: Onto the second!

Post by tomchaps »

Yep, I made the servo arm too long on purpose, with a lot of different holes to try out. It turns out the second hole worked best, so I'll trim it. And yeah, it's the servo that was recommended here (https://hobbyking.com/en_us/turnigytm-t ... c-21g.html), although it's not really pink.

And, it works! It even self-rights, barely. https://www.youtube.com/watch?v=RC0DYZd2GDw

The flip is pretty fast, but I do wish I had bent the titanium about 15 degrees at the bottom, so my flippy-victim would be less likely to slide off. Next time!

Thanks for your help. Off to fight in Robogames...
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Shakey
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Re: My first ant was not a success: Onto the second!

Post by Shakey »

tomchaps wrote:And yeah, it's the servo that was recommended here (https://hobbyking.com/en_us/turnigytm-t ... c-21g.html), although it's not really pink.
Yeah we still call it the 'pink servo'! :P

It's looking pretty good, good luck at robogames!
Nuts And Bots - For all your components and ready built antweights!

Alex Shakespeare - Team Shakey / Nuts And Bots / Team Nuts:
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Occashokka
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Re: My first ant was not a success: Onto the second!

Post by Occashokka »

But shakey why call it the pink servo when TGY-306G-HV rolls off the tongue so easily?
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tomchaps
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Re: My first ant was not a success: Onto the second!

Post by tomchaps »

Help! Finalized the chassis, got everything in, but when practicing driving I realized that I have an electronics problem.

When I actually try to lift anything, the receiver browns out. With no weight on it, it flaps up and down happily, but if there is any torque on the servo, it just dies.

I'm using tinyESCs from fingertech, which should be able to handle this.

Argh! What can I do? Safety checkin is in about eleven hours!
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