davidgeorge212

Hi, I am in a college class right now where we are getting ready for a robot competion that will be held down in Panama City Beach Florida in October. The competition will be held on the beach so the robot will half to be able to drive over sand. The objective is to drive your robot across the beach course (RC'd) but then when it enters into an outlined box, it must autonomously drive itself around and look for buried and semi buried peices of metal pipe. The robot must dig out and pick up the pipe from the sand. As soon as it has the pipe in hand and secured, The operater can take back over and drive (RC) it back to the goal box and then drop it in.

The rules also state that you can attack the other robot and or prevent them from getting more peices of pipe. So our robot should have some attacking mechanism as well as a good defense.

Our class is going to make some prototype robots using the LEGO NXT computer brains. Those are what we plan on using for the autonomous part of it. Once we get things worked out we will build bigger and stronger robots that can withstand attacks and other things.

I need some ideas though on ways to possibly dig down in the sand (if the pipe is buried below the surface) and ways to retrieve the pipe after it is within reach. Our first thought was to stick a magnet on the end of an arm that can be turned on and off which will allow it to pick up the pipe when its on, and let go of it when it is turned off. The pipe needs to be protected as well when it is carried back to the goal so the other robot can not steal it away from you.


I would appreciate any comments or feed back as well as ideas and suggestions from you guys,

Thanks,
David

dknovick

Some sort of rake or claws to sink down into the sand, wrap around the pipe and pull it up.
Some sort of blower or "street sweeper" to blow the sand away
A huge electro-magnet to just pull the pipe out from below the sand (but the magnetic field might mess up other things on the robot).

-Dave

davidgeorge212

We went out and tried a magnet to see if it would pull the pipe up from the sand. It worked like a charm. We burried the pipe vertical, horizontal, filled it with sand, left it hollow, and every time the magnet was still able to pick it up out of the sand. But we are in separate groups and not all of us can use the magnet idea so I will half to come up with more ideas. We are now pursuing some sort of claw or rake as another alternative. The problem I am having is that I just dont know what orientation the pipe will be in, horizontal or vertical. I still am not sure if the pipe is going to be fully or only partially burried because that would make a big difference. And on top of that, they could possibly throw us off by putting in all aluminum pipes so a magnet might not even work.

So now Im looking at some kind of rake or claw that can easily penatrate sand and pick up the peice of pipe weather it be vertical or horizontal or any other orientation.

Its not helping us either that right now we are limited to using these little nxt lego brains as our "autonoumous" source. Is anyone familiar with the Lego NXT robotics? Is it possible to get a better quality stronger motor and wire it to work with the nxt brain? right now we will half to use two motor for the drive wheels and that only leaves one motor to do another function. It would be neat to figure out how be able to use more than 3 motors and also, if its possible, upgrade to better motors.

davidgeorge212

Would anyone know if there is anyway to get a Futaba radio and reciever to work and be compatible somehow with a Lego NXT brain? Some how we half to switch from R/C to autonomous and then back to R/C again. Does anyone have suggestions for doing something like this?

Bastian Werner

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Regards

dknovick

I'm not familiar with Lego NXT, but I do know that FIRST uses Lego and other kits for their competition, and they have Teleoperated and autonomous sections

-Dave

Bastian Werner

Hey Guys,<o></o>

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Best,

buzzard350

My Feedback: (2)

You'd use an input from your R/C to switch on the autonomous controller, like a landing gear switch on the Transmitter (tx) for example. All commands would be generated through the microprocesor(s)controlling the vehicle

The code to the controller would be something like "if channel 7 is low, < all commands = received control inputs from tx >; if channel 7 is high, <subroutine from auto controller based on gyro, gps, or whatever> where channel 7 is the landing gear switch used in the example.

buzzard350

My Feedback: (2)

You'd use an input from your R/C to switch on the autonomous controller, like a landing gear switch on the Transmitter (tx) for example. All commands would be generated through the microprocesor(s)controlling the vehicle

The code to the controller would be something like "if channel 7 is low, [all commands = received control inputs from tx ]; if channel 7 is high, [control subroutine from auto controller based on gyro, gps, sensors or whatever] where channel 7 is the landing gear switch used in the example.

davidgeorge212

We current have a prototype robot chasis mocked up with some light go kart type wheels on it. We have been experimenting with motors and trying to see which ones will work to drive this bot. The bot is 2ft by 2 ft square and will weigh a good bit, roughly 50 lbs +/-, and it will half to drive over the sandy beach.

The robot will have 4 wheels that are on fixed axles so it is going to half "skid" steer to turn around. We need to find possibly 2 speed controls (one for the left side wheels and one for the right side wheels) that would allow us to drive the robot forward and reverse and turn left and right. Also we were trying to figure out how to control the bot with a regular 2 stick airplane radio (2.4ghz). We were thinking about adding a spring to the throttle stick so it would center in the middle like the elvator aileron stick. Then we would push both sticks forward to go forward and both backwards to reverse. For turning we would half to pull one stick back and push the other one forward. Im not exactly sure if that is a doable thing, can you hook up 2 speed controls in one reciever and control it the way I described?

I would love your input on this and the sooner the better. If you have any recomendations for speed controls and electric motors that would work for this, I would appreciate anything you can tell me.


Thanks,
David G.

davidgeorge212

I have a spektrum dx7 transmitter and some how I would like to figure out how to setup two speed controls to control both sets of wheels. It would be neat to plug in one motor and speed control to the throttle port and have the other speed contol and motor in the elevator port. That way you could have both sticks at neutral (centered) and to go forward you could push both sticks up and to backup you could pull both sticks down. Then to turn you could push one stick forward and pull the other stick back to turn it. It sounds like a good Idea but Im not sure how to program the transmitter to think neutral stick means stop and to switch from forward to reverse depending on where the stick is.

dknovick

I don' see why that would be a problem. The output from the receiver (in your robot) generates a signal to drive a servo. Most speed controllers take this signal and convert it into the proper commands to drive a motor. Any one of the channels could be used for a motor controller (or two in your case).

-Dave

alba1951

-Popsci just published an interesting concept for a simple robotic gripper: http://www.popsci.com/technology/art...obotic-gripper. Perhaps perhaps an enlarged 'spindly' version of it to grab the pipe in the sand.
-Another idea for thepipe retreiveris: http://toolmonger.com/2006/07/29/flexible-grabber-tool/. I have one in my shop and use it all the time to retreive nuts, bolts, washer, tool, etc. when working oncars. Works good!
Just some ideas to throw around,
Good luck!

MCRIPPPer

i really dobt an nxt will be of much use. the only way i can think of controlling one would be by bluetooth. mine is messed up. they are kind of pos. maybe i just got a bad one.