Extension Mechanism

[acer_7]

Hi all,
Hope ur all fine . .

I wanna ask about something please. I wanna make an extending pipe consisting of 2 or 3 layers and I want to make it very simple and speed is not important. I am participating in a robot contest and this mechanism is very important for me, so i really need ur help.

How can i use a motor for that type of extension? I need an extension for about 6 or 7 meters.

Thanks in advance . .

[Billfred]

Do you mean more like this:

http://www.chiefdelphi.com/forums/showthread.php?t=40098&highlight=extension+lift

or more like this:

http://www.chiefdelphi.com/forums/attachment.php?attachmentid=2834

The means for doing the two are somewhat different.

[Joe_Widen]

Ahh yes. Our team had something exactly like this. It was a cascading lift. It was in Billfred's second link on the left. What we did is we took 3 pipes and they cascaded. We used a CIM motor and the kop parts gearbox. Now it looks like you dont quite know what FIRST is. So here, you could by a CIM motor from < http://www.ifirobotics.com/first-store.shtml > its part number < FR801-001 >. Now buy gearing for a reduction of about 20:1 or 30:1. I recomend 3 stages. 2 through gearing and 1 through chain and sprocket. Now what we did is we went to a local sailing shop and bought sailboat pulleys and a white rope. They were both rated for 1500+ pounds. We took off the outer coating which is just for protection. We had 3 tubes that fit snuggly inside each other. I'm guessing you would want to use 3 tubes that are each 3 meters long and the one on the bottom being 2.5 meters. We used a mill to key each tube for the ropes to run. We drilled holes in the pipe near the edge and used a 1/8" stainless steel rod. We mounted the pulleys and tied the rope. Finally we welded it to 1/4" Aluminum disc and then hooked it all up to a 2.5" od spindle. The spindle was then hooked up to the cim with the gearing. I think ours was 27.16 to 1. I dont know much about the electrical part so someone else can help you there.

[Simon Strauss]

My suggestion is that you take a look at Greg Needel's presentation on designing competitive manipulators, which can be found here (http://www.usfirst.org/robotics/2006/Workshops/wrkpresentations.htm) if you scroll down about half way to where it says Needel. The presentation was quite good when i sat in on it at nationals and has a few ideas that should be helpful on how to pull off what was posted by Joe and Bilfred above. Also i suggest that you look through the rest of it because it has some interesting solutions for some other things that i have a feeling that you will need for whatever you are building. If you have any other questions on specifics Greg is reachable through these forums and myself and many others here either heard the presentation or know its contents and can help you if need.

also this (http://firstrobotics.uwaterloo.ca/armsgallery.php) might give you some ideas
-Simon

[acer_7]

Well, the type of extension i need is a horizontal one. I don't need to lift anything. I am using this extension mechanism as mean of blocking another robot. I have thought in the fork lifting mechanism like the one Billfred has sent in this link http://www.chiefdelphi.com/forums/a...tachmentid=2834 but I don't know how would it affect the balance of the robot; especially when u extend for about 6 meters.

If I used a light material, will it work ?

[Al Skierkiewicz]

Acer,
An extension for 6-7 meters would need some serious counter balance or a support at the end to hold up the extensions. How much stess will the device receive from the blocking action? Will the opposing robot be able to crash against your device? If the answer is yes, you might want to come up with a different strategy.
As to telescoping assemblies, Small Parts sells tubing that nests inside the next larger tube, but they are not long enough for the 6-7 meter dimension. On our robot lasst year, we used some drawer slides from McMaster Carr. They were heavy but allowed us to have and extension that went up to about 5 meters vertically with a 2 meter height when collapsed.

[RogerR]

Well, the type of extension i need is a horizontal one. I don't need to lift anything. I am using this extension mechanism as mean of blocking another robot. I have thought in the fork lifting mechanism like the one Billfred has sent in this link http://www.chiefdelphi.com/forums/a...tachmentid=2834 but I don't know how would it affect the balance of the robot; especially when u extend for about 6 meters.

If I used a light material, will it work ?

i'm not sure what how stiff your blocking mechanism needs to be, but maybe a nuremburg scissors (http://firstrobotics.net/00gallery/pages/056-1_jpg.htm) mechanism would be better suited? it folds up relatively compactly, and is fairly simple to actuate. on the down side, they can be somewhat flimsy, especially when fully extended (the reason i tend to shy away from them).

[Joe_Widen]

Well, if you can give a more accurate description of what you need it to do, I'll be more then happy to cad one for you. I'm on summer break.....what else do I have to do?

[acer_7]

Umm . . I will try to explain it more guys & thx for all these replies.

Inspite of the extension being desired to be 6-7 meteres, I don't need it to be stiff at all. I just want it to reach a specific area. The robot competition - I am participating in - has a special playground. Besides, I got a specific start zone for my robots that has limited dimensions. The robot carrying this extension mechanism should have a maximum dimension of 500*1000*2000mm (2000mm is the height).

The scissors mechanism is great but for such distance I need to use large ones and I don't have the place for it as I am using my robot for other things and there are other stuff placed on it.

Can't the forklifting mechanism be modified for such purpose ? I also thought that I would use a fishing rod but I couldn't get an idea for extending them using motors or pulleys. Air was another idea to use in extending the rod but to use that I need an electromagnetic switch and other pneumatic stuff.

[Andy Baker]

Umm . . I will try to explain it more guys & thx for all these replies.

Inspite of the extension being desired to be 6-7 meteres, I don't need it to be stiff at all. I just want it to reach a specific area.

If you don't need it to be stiff, then you can unroll a thin sheet of spring steel, much like a tape measure. This can be motorized, as the steel tape can be shot out (at about 25cm/sec) and recoiled with the same motor.

Is the arm simply touching something 6-7 meters away? If so, then the above suggestion works well.

Good luck,
Andy B.

[Richard Wallace]

Can this be a one-shot mechanism; i.e., can it start within the original 500 x 1000 x 2000 limits, then deploy once to reach the 6000 - 7000 height, requiring manual intervention to get it back to the starting configuration?

And how much payload do you need to raise to the target height?

[edit: I was thinking of some shock-corded tent poles with sections of fishing rod to deploy them.]

[Billfred]

I also thought that I would use a fishing rod but I couldn't get an idea for extending them using motors or pulleys.
Well, here's an idea that might work for you. Have a mass (how much depends on fifty other things) on the end of your line, which you plant at the location. You then drive about with the reel disengaged, like you were casting the line if you were using the rod for its intended purpose. Once you're ready to unblock, engage the reel and start turning.

[Joe_Widen]

Here, coudl you string 6 of these together and using one pneumatic piston to get the first on out. Then you could hinge the rest together and use a fishing line and rell to pull on them and get them out?

http://www.chiefdelphi.com/media/photos/25088

[Al Skierkiewicz]

Umm . . I will try to explain it more guys & thx for all these replies.

Inspite of the extension being desired to be 6-7 meteres, I don't need it to be stiff at all. I just want it to reach a specific area. The robot competition - I am participating in - has a special playground.


Acer,
Are the rules published on the web so we can see them? It might help if we could get a complete picture. Several years ago, our competition had a requirement that allowed many teams to use Andy's suggestion above. There was great fun and anticipation waiting for the "magic tongue" to deploy at the end of a match.

[Andy Baker]

Several years ago, our competition had a requirement that allowed many teams to use Andy's suggestion above. There was great fun and anticipation waiting for the "magic tongue" to deploy at the end of a match.

Does anyone have any old videos or pictures of tape measure deployment or coils of spring steel unrolling from the 2002 FIRST Competition? If this mechanism is legal for Acer's competition, we can all pick the best of these mechanisms and give Acer some good examples.

292 had a motorized tape measure by the end of the season... it was really neat.

111 had a reliable unrolling steel coil.

535 had a bigger version of a motorized coil... it was very impressive.

Andy

[Rohith Surampudi]

I would suggest the usage of NiTinol Wire that can be found here (http://www.nitinol.com/) Nitinol stands for NIckel TItanium Naval Ordnance Laboratory, it is a shape memory wire, that will resume its original shape if a charge is run through it. To choose the shape, all you need to do is bend the wire to the shape you want it to return to, then heat up the bent areas, or the entire thing. The only problem i could forsee, is that because of the heat that is produced by the resistance, NiTinol wire does note come with the rubber coating, therefore it is open voltage. Fairly thin pieces can be obtained in order to only require a small amount of power, but the thicker the wire is, the more power it will require. If you have any questions please email me, Good luck :)

[lukevanoort]

Does anyone have any old videos or pictures of tape measure deployment or coils of spring steel unrolling from the 2002 FIRST Competition? If this mechanism is legal for Acer's competition, we can all pick the best of these mechanisms and give Acer some good examples.

292 had a motorized tape measure by the end of the season... it was really neat.

111 had a reliable unrolling steel coil.

535 had a bigger version of a motorized coil... it was very impressive.

Andy
I do, but they're all on VHS :(

[acer_7]

Great ideas ! I hope u can supply me with more details concerning the tape issue.

To give u more idea about my competition, you can download the rules and see its video from the following site http://www.robofest.org.my/robocon2006/

I don't know if u've ever heard of ABU robocon contest before. It's an international competition for the member countries Asia Broadcasting Union (ABU). It includes Japan, China, Korea, Egypt, Vietnam, Malaysia....etc

Each year a country hosts the event but before the international event there's a local competition in each country to choose the team representing your country. The competition includes a manual robot and several automatic robots and there's a specific task to do. Ur limited within a specific weight and a specific dimension.

The following link http://gymkhana.iitb.ac.in/~umic/videos/robocon2k5/robocon2k5.wmv
gives u an idea how the international competition was fierce last year. U'll see the fastest extensions u have ever seen in ur life.

By the way I forgot to introduce myself. I am a student at the Electronics and Communications department, Faculty of Engineering, Cairo University. Glad to meet u all :)

[sanddrag]

Wow, what a great video. Man, and I thought FRC was hard. And look how lightweight those robots are - they pick them up with one hand!

I'm concerned about safety with humans on the field with the robots though. That looked very dangerous to me. Safety is one thing FIRST has done very well.

How long do you get to build these things anyway?

[Rohith Surampudi]

The following link http://gymkhana.iitb.ac.in/~umic/videos/robocon2k5/robocon2k5.wmv
gives u an idea how the international competition was fierce last year. U'll see the fastest extensions u have ever seen in ur life.

By the way I forgot to introduce myself. I am a student at the Electronics and Communications department, Faculty of Engineering, Cairo University. Glad to meet u all :)


Heh, i see dumper bots

[Billfred]

Great ideas ! I hope u can supply me with more details concerning the tape issue.

To give u more idea about my competition, you can download the rules and see its video from the following site http://www.robofest.org.my/robocon2006/

I don't know if u've ever heard of ABU robocon contest before. It's an international competition for the member countries Asia Broadcasting Union (ABU). It includes Japan, China, Korea, Egypt, Vietnam, Malaysia....etc

Each year a country hosts the event but before the international event there's a local competition in each country to choose the team representing your country. The competition includes a manual robot and several automatic robots and there's a specific task to do. Ur limited within a specific weight and a specific dimension.

The following link http://gymkhana.iitb.ac.in/~umic/videos/robocon2k5/robocon2k5.wmv
gives u an idea how the international competition was fierce last year. U'll see the fastest extensions u have ever seen in ur life.

By the way I forgot to introduce myself. I am a student at the Electronics and Communications department, Faculty of Engineering, Cairo University. Glad to meet u all :)
Holy smokes! Now THAT looks like fun!

I like the combination of autonomous-only and human-operated robots running at the same time. (It seems like we could do something similar with Vex, but on a smaller scale.)

[Richard Wallace]

... To give u more idea about my competition, you can download the rules and see its video from the following site http://www.robofest.org.my/robocon2006/

I don't know if u've ever heard of ABU robocon contest before. It's an international competition for the member countries Asia Broadcasting Union (ABU). It includes Japan, China, Korea, Egypt, Vietnam, Malaysia....etc

Each year a country hosts the event but before the international event there's a local competition in each country to choose the team representing your country. The competition includes a manual robot and several automatic robots and there's a specific task to do. Ur limited within a specific weight and a specific dimension.

The following link http://gymkhana.iitb.ac.in/~umic/videos/robocon2k5/robocon2k5.wmv
gives u an idea how the international competition was fierce last year. U'll see the fastest extensions u have ever seen in ur life.

By the way I forgot to introduce myself. I am a student at the Electronics and Communications department, Faculty of Engineering, Cairo University. Glad to meet u all :)I read the rules and FAQ for ABU Robocon. It seems like an exciting competition. You and your team at Cairo University will probably be very busy until the first week of July, preparing for your national competition. Good luck with that.

Will the winner of your national competition get to represent Egypt at the September event in Kuala Lumpur? How many teams will be competing in your national event?

[acer_7]

Actually, safety is very important in this competition. Dangerous robots aren't allowed to join the contest. There's also a robot test before the competition to make sure of safety and ensure restrictions as well.

I am in the middle of my final exams now. I am supposed to finish them on the 17th of July then I will work through 2 weeks to get ready for our competition from 2-6 July. That's why I am trying to look up for as many ideas as I can to try through this period of time. So, please if u gotta anymore ideas i will be glad to hear them.

There are about 67 teams joining the national competition this year. The winner will represent Egypt in Kuala Lumpur.

After some of u have seen the video, u've seen what I mean. I don't need a stiff extension, just a one that blocks the target for the opponent robot. I don't need my extension mechanism to be that fast. China has used pneumatic mechanism with bamboo fishing rods while Japan has used springs.

Check this link http://www.tpa.or.th/robot/tparobot/20060520/image/DSC_0374.jpg
This if from this year's Thailand competition

I have the following thoughts:
======================
- A fishing rod with a motor and a wire (or tape) [but I just need to understand how to install it]
- Something like that picture (see the inclined extension). It consists of successive layers beside each other.

What do u think ? (especially that my time is limited after my exams, I have only 2 weeks beside the work in the other robots)

[Richard Wallace]

I noticed in the rules for ABU Robocon that the machines must be handmade.

Does "handmade" mean you are not allowed to used automated processes or tools to fabricate components of the machine? What about power tools? Do you have to fabricate all the parts of your machine by hand? And are there any restrictions on what purchased parts you can use or how much you can spend on parts?

[acer_7]

'handmade' means that u don't buy a complete robot arm for example. We are allowed to use tools to build our robot. Actually most of the teams go to workshops for cutting and welding aluminium for example. U sometimes need blacksmith work; like attaching the motor to ur wheels. U can buy simple ready things but not whole made things.

[Richard Wallace]

That seems very reasonable. Back in the early years of our competition, FIRST had fairly simple rules. More recently, the rules have generally become more complex each year. For several years now we have had increasingly intricate rules aimed at keeping our robots "handmade". These take the form of limits on total cost of purchased materials and components, limits on the cost of individual components, and a rather lawyerly definition of what is a commercial off-the-shelf (COTS) component. You can find the rules governing robot construction for 2006 FIRST robotics competition here (http://www2.usfirst.org/2006comp/Manual/5-The_Robot_Rev_F.pdf).

I am really drawn to the idea of replacing a large portion of our robot rules with the simpler requirement that the robot must be handmade.

[acer_7]

I don't know about FIRST actually. I took a quick look at the rules and found that u use kits for making robots. That's totally opposing to us, I can't remember anything we've bought ready-made till now. We even search the surplus markets for special types of nuts to combine aluminium sheets together so that they won't separate.

[Alan Anderson]

I took a quick look at the rules and found that u use kits for making robots.
Don't misunderstand the meaning of "Kit of Parts". It's not a robot kit. It's essentially a bin of donated motors, pneumatic components, gears, connectors, chains, wheels, cheap joysticks, software, sealed lead-acid batteries, etc.

There are a few more high-level things in the KoP: the equivalent of an erector set for making a simple chassis if you want to, reducing gearboxes (some assembly required)...and the full programmable control system with RF communication. But it's not a "robot kit" that teams "put together" to make robots.

[acer_7]

Hey guys,
Does anyone one knows how does the car antenna extend (from the mechanical and electrical sides)?

[Tristan Lall]

Hey guys,
Does anyone one knows how does the car antenna extend (from the mechanical and electrical sides)?On most vehicles, its a 12 V DC motor with a pulley and a stiff cable that's pushed upward or pulled downward.

http://www.lincolnvscadillac.com/tech/lincoln-town-car/Lincoln-Power-Antenna-Mast-Replacement/LincolnPwrAntR09160310x.jpg (http://www.lincolnvscadillac.com/tech/lincoln-town-car/Lincoln-Power-Antenna-Mast-Replacement/)

[Al Skierkiewicz]

Hey guys,
Does anyone one knows how does the car antenna extend (from the mechanical and electrical sides)?
As shown in the picture above, many have a plastic rack gear driven by a pinion on the shaft of a motor. The drawback it that for extension, the rack must slide up inside the telescoping tubing sections without binding. Since the tubing is thin wall, there is not a lot of dimensional change between the inside tube and the outside tube. (about three or four telescoping sections maximum) The sections are designed in such a way that the inner one has a larger outside diameter at the bottom of the tube than the inside diameter of the next larger tube. As the inner tube extends, it "grabs" the outer tube and so forth for all of tubes.
There is a fishing pole available through several outlets here in the US (Cabellas and Gander Mountain). It is called a breem pole or sunfish pole. It is made of fiberglass and graphite composite. It starts a little less than 2 meters long and extends for almost 7 meters. It is very lightweight. Many ham radio operators here use this pole for portable antennas. The design is a friction fit between pole sections and it operates much like the power antenna above. Cost in US about $20 plus shipping.
An antenna article here uses such a pole. http://members.aol.com/realhamradio2/W2IK-ANTENNA.html

[acer_7]

Thx a lot . . got it