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Old Jul 18, 2006, 12:00 PM
Robot, RC Pilot & Builder :-)
kevinhines's Avatar
Roanoke, VA, USA
Joined Jul 2006
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Orlando Robotics

A group of friends, here in the Orlando area, are building robots, often with the Vex kits, and we're having a lot of fun.

If you are in the Central Florida region, please say hello!

I am currently building a three omniwheel, omnidirectional robot, and am working to incorporate a gyro as a rotation rate and heading direction sensor. I'm using the Vex microcontroller for mixing and heading feedback control.

I'll post pictures of my bots here as well.

Thanks,
Kevin

Kevin Hines
KevinHines@aol.com
www.OrlandoRobotics.org
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Old Jul 18, 2006, 12:53 PM
Things are looking up...
mechrick's Avatar
Orlando, Florida
Joined Nov 2004
1,385 Posts
Quote:
Originally Posted by kevinhines
A group of friends, here in the Orlando area, are building robots, often with the Vex kits, and we're having a lot of fun.

If you are in the Central Florida region, please say hello!

Kevin Hines
Welcome to RCGroups Kevin!

Let's keep this thread going for Orlando Vex (or other robotics) and welcome all others to share and trade ideas.

Rick
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Old Jul 18, 2006, 01:22 PM
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Joined Jul 2006
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That's a nice three wheeled bot!

My three wheeled robot has two wheels which do not move and a third in the front. The wheel in the front is hooked up to a servo and can turn -90 to +90 degrees.

Regards,

Doug
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Old Jul 18, 2006, 07:32 PM
Things are looking up...
mechrick's Avatar
Orlando, Florida
Joined Nov 2004
1,385 Posts
Here's my first bot, a dog toy retriever, just to get the feel for the Vex components. I haven't started playing with the limit interrupt devices yet, but I'm impressed with the Vex set so far. I did add a remote micro wireless camera to drive around the house picking up dog toys while sitting at my computer, and did that for a couple of nights till the family got too annoyed. And the dogs did not seem to appreciate it.

Next up maybe a ping-pong ball gatherer and shooter, to give the dogs something to chase or retrieve.

Rick
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Old Jul 19, 2006, 12:43 AM
Robot, RC Pilot & Builder :-)
kevinhines's Avatar
Roanoke, VA, USA
Joined Jul 2006
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Hi Guys,

Please allow me to introduce you both: Doug is my brother, and Rick is my friend at work (in spite of his better judgement), each of us have begun building with Vex kits, und wir allen koennen auf deutsch sprechen.
:-) (translation for everyone else: "and we can all speak German")

Rick's bot is cool, but I didn't realize, Rick, that you had used it to terrorize poor Minna! Tsk Tsk! Please do build the ping pong ball retriever and shooter, I'd like to learn how you do this.

Doug, if you want to post pictures of your car-steering bot, that would be cool.

Now hopefully we can get other folks (Steve, Mike, Greg...) to join in and post here.

Regards,
Kevin
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Old Jul 19, 2006, 10:36 AM
Things are looking up...
mechrick's Avatar
Orlando, Florida
Joined Nov 2004
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Quote:
Originally Posted by kevinhines
Hi Guys,

Rick's bot is cool, but I didn't realize, Rick, that you had used it to terrorize poor Minna! Tsk Tsk!

Regards,
Kevin
Terrorize is such a harsh word for driving past a sleeping dog and waking her.

I need to cut up some of my big structures pieces (as I note you did for your omnibot) so I can make better interfaces.

Rick
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Old Jul 19, 2006, 04:26 PM
Robot, RC Pilot & Builder :-)
kevinhines's Avatar
Roanoke, VA, USA
Joined Jul 2006
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Quote:
Originally Posted by mechrick
Terrorize is such a harsh word for driving past a sleeping dog and waking her.
Now I understand why you wanted to add the hex standoffs as "teeth" for your bot's "jaws." To retrieve the dogs themselves!

A Dremel cutoff wheel works well for cutting the steel Vex parts to size (it's less work than using a hacksaw). Either way, of course, one must still file away the burrs. One of the best parts about using the Dremel cutoff wheel are the sparks!

Speaking of your bot arm picking things up, I'd like to build a robotic lifting arm that could quickly lift much more than it's own weight. For example, I'd like to build a robotic arm that weighs less than a pound, could grasp & lift a one to two pound weight, up one to two feet into the air, all in less than half a second. Do you have any ideas or suggestions?

Thanks,
Kevin
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Old Jul 20, 2006, 09:37 PM
Things are looking up...
mechrick's Avatar
Orlando, Florida
Joined Nov 2004
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Quote:
Originally Posted by kevinhines
I'd like to build a robotic lifting arm that could quickly lift much more than it's own weight. For example, I'd like to build a robotic arm that weighs less than a pound, could grasp & lift a one to two pound weight, up one to two feet into the air, all in less than half a second. Do you have any ideas or suggestions?

Thanks,
Kevin
The Vex motors and servos are pretty light duty, even with gearing, to think about lifting heavy things (like 2 pounds ).

Using the largest and smallest gears and a Vex motor you could make a simple pully to pick up 2 pounds. You can make a light frame with a base that would surround the object like a "U" (see my tank track frame if the front bar were removed). But, a pully system will be slow.

If you want to move something that quickly (to launch it?) you might think about storing energy in spring, with a geared-up (or is it down?) motor system to pull it into the compressed position. That's the easy way to launch light ping pong balls. If you took the basic see-saw part of my bot and put a scoop on the front, maybe you could spring load the elevation axis and pull it down in the rear into a "catch", winding up a strong spring, drive under your object, and release the mechanism.

Or buy the pneumatic Vex add on and build an air firing lifting arm. Sounds like you want to build the old "Toro" robot from Battle-Bots.

Rick
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Old Jul 20, 2006, 10:51 PM
Robot, RC Pilot & Builder :-)
kevinhines's Avatar
Roanoke, VA, USA
Joined Jul 2006
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Would a Vex electric motor output alone be powerful enough?

If the power output could be obtained, then I think the proper gearing up/down could be found.

Hmmm, power = force x distance / time

The weight of 2 lb is about 1 kg, which weighs 9.8 Newtons, say 10 N, and...

To accelerate the object upwards at say 1 g (just a guess), would require 2 times the weight... so...

power = force x distance / time
= 20 N x 0.5 m / 0.5 sec
= 20 Nm/sec
= 20 Watts of mechanical power
= 0.026 horsepower

Ignoring efficiency for the moment, then this would require a minimum of 20W of electrical power, so at 7.2V, this would require over 3 Amps.

The Vex motors are rated up to about 2A at stall, so 1 Vex motor is out of the question, I think.

Perhaps using a few Vex motors ganged together could supply this much mechanical power? But I don't know if the Vex controller would be okay with that much current flowing through it.

Or another option would be to use a more powerful electrical motor, controlled by either with speed controller for proportional control, or simply an on/off relay switch.

Also, the battery powering the lifting motor(s) would need to be able to supply the required power (voltage x amps).

What did I miss?

What are your thoughts about the practicality of doing this with electrical motors?

Kevin

PS - Toro is very cool.
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Old Jul 21, 2006, 12:08 PM
Robot, RC Pilot & Builder :-)
kevinhines's Avatar
Roanoke, VA, USA
Joined Jul 2006
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Here are some pictures of the GWS Beaver RC Airplane Kit I'm working on. I think I'm about 40% complete with the build.

Rick, thanks for your inputs regarding how to build this kit.

Kevin
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Old Jul 21, 2006, 01:11 PM
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BlueAnodizeAl's Avatar
Orlando, FL
Joined Dec 2004
376 Posts
Looks great, Kevin! Excellent, and very clean first build!

Will you be ready for tomorrow morning?


Rick,

These improvements look like just the ticket, you may want to send them to GWS for a rev of their instructions. Or post the redlines in the GWS forum for newbies. I'll definitely be applying all of them to Bill's E-Starter next month.

We may also want to move this post as a new thread in the e-flight beginner's forum.

-Mike
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Old Jul 21, 2006, 02:15 PM
Things are looking up...
mechrick's Avatar
Orlando, Florida
Joined Nov 2004
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Looking great Kevin! Get it ready and we'll fly on Sunday. We will be going to a new field near Kissimee, down John Young. I've never been there but Mike knows the way. It may be closer to you. I'll try and get my plane done also so we can both fly Beavers. We'll then take these posts to the flying forums, as we are really supposed to be talkin' robots here you know.

Rick
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Old Jul 21, 2006, 05:46 PM
Robot, RC Pilot & Builder :-)
kevinhines's Avatar
Roanoke, VA, USA
Joined Jul 2006
4,180 Posts
Guys, Thanks for all the advice and encouragement. I'm looking forward to flying together on Sunday morning.

Please do post either a link to a map, or a map itself, or directions to the John Young location, and also the time we should plan to meet.

Thanks,
Kevin
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Old Jul 21, 2006, 06:01 PM
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Orlando, FL
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376 Posts
I made the map from Sand Lake Road and International Dr as a landmark for all of us.
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Old Jul 21, 2006, 06:02 PM
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Orlando, FL
Joined Dec 2004
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Remember that if you take SR 417 to John Young; John Young becomes S. OBT about 12 miles down the road. So if you just go straight, you'll be fine.
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