Let's Make Robots!

NewBOT

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treads1.JPG59.64 KB
ground_clearance.JPG50.63 KB
chassis1.JPG52.06 KB
chassis2.JPG51.83 KB
tread_unit_removal.JPG44.43 KB
Power_and_Prog.JPG153.99 KB
Motor_Controller.jpg64.87 KB

9-Oct-08 - First Drive!

Always a proud day, like baby's first steps. In the video i'm using the WASD keys to drive and steer. The speed control is working very nicely. With the manual control I am currently dividing the 10-bit pulse width into 10 gradients which makes it a little jerky. When autonomous it will be allowed 100 discreet speeds in either direction. It's open loop for now because i haven't found any encoders small enough/cheap enough.

The install of the motor controller into the track unit was frustrating (very short wires) but it turned out nice. I'll post somepics and a video demoing the ease of disassembly soon. I have been collecting inspiration over the last couple of weeks and will leave you with this:

http://www.youtube.com/watch?v=Y6ljFaKRTrI&feature=related

 

29-Sep-08 - Finally....POWER!

So, after a lot of playing with different power sources, I decided to go with some good quality, 3A low drop-out linear regulators. I'm still playing with the boost circuit, but I didn't want it slowing down this project, so they are diverging for now and hopefully I will add it back in later.

Last night I got it up and running a few test programs. The Pololu soft power switch is very, very nice. I tested one of the motor controllers (just fwd and rev) and wrote some routines to handle the pulse width so tonight I should have some first drive video for you. But here are some pics for now.

Power_and_Prog.JPG

Motor_Controller.jpg

 

 

 

 

 

 

 

 

 

 

 

25-Sep-08 - A Step Back in Power

So due to an error in the digikey catalog, the voltage regulators that I bought don't work for my application. The catalog says the drop-out voltage is 3 Volts when its actually 7V!!! So I'm redesigning the power circuit to mock the power circuit on the Pololu 3pi, which runs down to 1.6Volts!!! They do it with a very nice Boost regulator that runs at 9.25 Volts and feeds a linear regulator. Check out the schematic if you're interested, its a REALLY nice way to run a robot off of 4-6 AA batteries and really get all the juice out of your batteries:

http://www.pololu.com/file/0J122/3pi_quickstart.pdf (top of page 2)

They wouldn't tell me what the boost regulator was because they are going to start producing/selling thepower circuit, but luckily I have a friend that has a 3pi prototype so we figured it out. They parts are on the way! This will set back my first drive till sometime next week. Sorry Fritz :-)

23-Sep-08 - Change of motor plans

So I've decided not to use the Solarbotics GM10 (http://www.solarbotics.com/products/gm10/) motors. I have 4 of these to spare if anyone needs them send me an email at thekeywork2@gmail.com and we can talk about it. Please do NOT post in the comments section, just shoot me an email.

As for the robot, i'm building the power circuit today (pics tonight) and starting on the code. I've decided on the pololu TB6612NFG motor controllers for the drive wheels (http://www.pololu.com/catalog/product/713).

19-Sep-08 - Another Elaborate Chassis

OK, OK...I broke away from the minimalist simplicity of my last project (http://letsmakerobots.com/node/1996) and built a slightly more elaborate chassis. The box is made from sintra and is held together using counterbored 2-56 screws. The "tread units" come off with a single screw (later a single screw and connector for power and control) and i'm planning on housing the motor driver inside the individual tread units making them fully detachable. I like compartmentalisation for some reason. check back soon!

 

chassis1.JPG

chassis2.JPGtread_unit_removal.JPG

 

 

 

 

 

 

 

 

19-Sep-08 - Ground Clearance

Great idea voodoobot! Check out the new pic to see this implemented. It allows for 1.5" of ground clearance. This is with 22 links of Solarbotics tread with a 3" wheelbase. I used 1/4"-20 shoulder screws to mount the idlers (had to bore them out just a little) and 3mm Sintra (expanded PVC) for thesupport structure. Now that the treads are done, today i'll be working on chassis design and motor controller/processor placement. Check back soon!

New motor placement1.5

 

 

 

 

 

 

 

 

18-Sep-08 - A Clean Start

So I've wanted to build a tracked robot for quite some time, but have never found any tracks that I really liked until I found this website, saw the YDM, and fell in love with the solarbotics tracks. So here is the start of my next robot. I won't give way too much right now except that i'm using an RCM3400 processor from rabbit semi and am going for a YDM-like final result.

Pictured is my track layout. I integrated the GM8 motor into the track holder so that the track-drive mechanisms are separate components.

Oh, and I never name robots till they are done...hence NewBOT.

 

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What's the little round parts on each tread? Are they for traction, for slipping? Kinda dresses them up, if nothing else.
I'm suprised it took so long for that to come up.  each link is drilled with a 1/4" hole, counterbored on the under side with a 3/8" endmill about 0.035" deep and fixed with a rubber grommet.  I was hoping to develop a little more traction and went a little over the top.

WOW. I love the look of the material and the triangle track set up. Are you intentionally making a wall-E type bot? If wall=E was brand spankin new thats what I imagine he would look like!

Depending on your main floor surface those rubber grommets on the tracks might make turning tough. My last robot used the cheap tamiya tracks and it always throws one off trying to turn on my rugs.

Incidentally, that stuff sintra, is it easy to find and work with? Im looking for material to use on my next bot but I dont know what I should get, and living in an apartment I`m limited on how much drilling and sawing I can do :/

i'm hoping for more of a multi-terrain robot. I've got the high-torque motors on it right now. i might switch to the high speed if turning isn't an issue. i just wanted multi-terrain capabilities and those treads have NO grip out of the box.

I got the Sintra from solarbotics because i was already ordering from them, but i'd normally just get the regular expanded PVC that they sell at mcmaster. the sintra stuff is less dense and cuts easier if you dont have access to machine tools, but they are both light weight and take well to machining, hand cutting, sanding and glueing.

 

Oh, and definately Wall-E inspired! 

looks awesome! 

btw, is that coolant(80/20 mix) in the bottle in the top(new) pic, or is it some new wierd gatorade?!?!?! ...what are you building that requires that?!?!  :)

lol! thats actually 50/50 propylene glycol.  We use it for watercooling the CPU in our stereovision/autonomy unit.  but yeah, it is in a limeade container.  very professional, i know.
Your style is wicked!! I need words.. wicked!
Thanks dude. I'm sparing no amount of engineering on this one.  Full 3d cad in solidworks, and the RCM3400 is super overpowered for this app! i'm wicked psyched!
Looks Great ! Keep up the good work !

I've been looking at this design as well, haven't bout the tread kit though just yet.

Have you looked at mounting the motor on the higher sprocket to give a bit more ground clearance? Thats one of the issues that I found with the 2 sprocket setups, always too low and anable to get over angled terrain due to underside clearance. 3 sprock with the high motor mount seems best to solve this.