Treads, Tracks, Tank system Talk/Help

[Al Skierkiewicz]

Mr. Rush,
Treads of this type were common at one time and the color of the cleats that appear in your photo, appear to be made of aluminum, another common design of years past. It is to that type of design to which I made reference. As to the tripping of breakers, I would bet that on carpet they were tripping. Not as often as other designs due to the small turning radius but there none the less. Rack it up to thousands of hours of experience with FIRST robots gained over a 13 year period. As a rule of thumb, any drive with high side friction will send the motors into stall or near stall. On the van door motors in the photo , that is 69 amps per motor as I remember. As to the reference to rules, I have to interject that as a Lead Robot Inspector. Often team members make decisions based on their expectation of rules and neglect to examine closely the changes that occur every year following kickoff. For instance, there is no guarantee that the motors you have used in the past will be present in 2009.

[Mr.Rush]

Well Al you're wrong the cleats as you have dubbed them are hardened rubber, The vandoor motors powered a set of arms not the drive train. You are making too many assumptions. It was powered by a pair of dewalt drills. Feel free to toss as many self important titles as you want around but quite frankly you can take you high horse and shove it.
I am more than aware that things change (the removal of the mini bike motor from the kit of parts as an example). I also under stand that the current changes based on load. And once again we point out that the discussed drive trains aren't necessarily intended for FIRST competition use. Aspects of them might be used if permitted, but if I understand void's goals this thread was meant to gather knowledge , no finalize any design.

[Madison]

Originally Posted by Mr.Rush

Well Al you're wrong the cleats as you have dubbed them are hardened rubber, The vandoor motors powered a set of arms not the drive train. You are making too many assumptions. It was powered by a pair of dewalt drills. Feel free to toss as many self important titles as you want around but quite frankly you can take you high horse and shove it.

Watch it.

When someone asks for help, they ought to be grateful for what they receive rather than complain that they aren't getting what they want. Ask more questions, refine your language and clarify your thoughts if things don't go the way you'd like, but know that it's patently absurd to think that insulting anyone, threatening to close the thread, or anything like that is going to make things better.


Someone said it best when they said, "You take the good, you take the bad, you take them both and their you have the facts of life."

[Alan Anderson]

Originally Posted by Mr.Rush

...The vandoor motors powered a set of arms not the drive train. You are making too many assumptions. It was powered by a pair of dewalt drills.

The motors I see connected to the drive sure look like van door motors. Are you sure you're describing the same robot you posted a picture of? There is a lot of wiring blocking the view, but it doesn't seem to show either arms or drill motors.

...I also under stand that the current changes based on load...

Your understanding is incomplete. A totally unloaded motor still draws its stall current for a moment as it begins to spin.

[Mr.Rush]

the arms are the two inch thick portions of lexan between the main body and the tracks them selves if need be I'll take a picture of the gutted and cleaned robot net shop day. The main drive is indeed drill motors.

As for my insulting people the Origional poster clearly said he understood that the tread style drive had its draw backs and he understood that, thus having people posting in this thread proclaiming the drawbacks have been unnecessary posts, and not contributing to the topic.

Your understanding is incomplete. A totally unloaded motor still draws its stall current for a moment as it begins to spin.

Of this I was also aware, My wording might not have been clear however.

[IKE]

Lego NXT Johnny 5.

Pretty cool. I am amazed what people can do with legos.

[Al Skierkiewicz]

Mr. Rush,
You have jumped to a number of assumptions as well. The original poster and I have communicated privately and I am merely adding to the discussion for the benefit of those others that are reading this thread. Don't forget, there are many who lurk here who will gather wrong impressions if just reading uniformed posts. When someone asks for help (including you) I will give them as much information as I deem necessary for the original question(s).
As to the van door vs. drill, you have now taken it to another level as the drill motors draw between 95 and 100 amps depending on which factory they came from. Should there only be two motors then the issue with the power source remains but is lessened over the short term. Beyond about 4-5 minutes of run time, the battery will still fall to below the required eight volts at which the RC ceases to function or switches to backup battery. Since no backup battery is visible I can assume that the RC is an early version and will simply shut down during these high current situations and the result is a four to five second reboot. I believe it was stated earlier that this is a 2001 robot which would put the RC in the pre backup version.
As to the composition of the cleats, being plastic or rubber or aluminum does violate 2008 rule R06 "Traction devices shall not have surface features such as metal, sandpaper, hard plastic studs, cleats, or other attachments". Since this important for students thinking about their 2009 robot, I included it in my previous discussion.
As to gathering knowledge, is it better to fail and fail and fail yet again or ask and receive knowledge from one who has experience. It seems like the old adage "Don't reinvent the wheel" applies.

[Mr.Rush]

I too have been talking with the Original poster (the room mate he mentioned) and neither of us are students at this time. The robot is currently using the radio from the past two years not the old radio, and even in this design there was a backup battery mounted underneath the rest of the electronics board. We've installed a new "brain" using parts left over from the past two years. We've talked to more than a few of the old guard for reason for the design. It was built to fit under the fence and the balance beam utilized in that years game, It was they admit not the greatest of robots but it was a niche robot one of the few capable of both functions. On its own it couldn't score very well on its own, yet was desired on an alliance.

Its good in my opinion to think about the past and understand the odd ball designs that have worked in the past and consider how they differed from the others to push the envelope that much further. Bomb Squad is one of those teams who make a good show, Metal Emotion back in the day, and who can forget the Overdrive exploits of the robot Tumbleweed.

I apologize for my out burst earlier as well. I know you mean well its just a pet peeve of mine to see topics blown apart by people spouting rules.

[EricH]

Originally Posted by Mr.Rush

The robot is currently using the radio from the past two years not the old radio, and even in this design there was a backup battery mounted underneath the rest of the electronics board. We've installed a new "brain" using parts left over from the past two years. [...]
Its good in my opinion to think about the past and understand the odd ball designs that have worked in the past and consider how they differed from the others to push the envelope that much further. Bomb squat is one of those teams who make a good show, Metal emotion back in the day, and who can forget the Overdrive exploits of the robot Tumbleweed.

In other words, there has been a slight redesign for a newer controller. That is good. (I say this because pre-2004, there wasn't even a capability for a backup battery.)

Yes, it is good to think about the past. You can get some great ideas that way. However, you have to re-engineer them to fit current rules. Let's take the 1998, 2001, and 2004 big-ball robots and see how they play Overdrive. They'd do fairly well, with a little rebuilding to comply with ball size. Now use the 2008 motors.

[Mr.Rush]

Oh it seems there were some typos in my post weren't there? Now that was an honest mistake....need to not be writing these post on an I-pod touch...

[IKE]

Interesting idea for treaded vehicle manueverability.
Have the treads be speparate articulating pds from the main body. do a high pivot on the rear structure that way when turning it would jack the inside tread pod and give a single point of contact on the inside.

[IndySam]

I would love to do a tank design using links like a real tank and the rollers from an AM 6" mecanum wheel mounted sideways. Kind of like a omni tread. Or maybe even a few rubber links spaced in the tread to help give a little resistance to sideways pushing.

[JesseK]

Originally Posted by IndySam

I would love to do a tank design using links like a real tank and the rollers from an AM 6" mecanum wheel mounted sideways. Kind of like a omni tread. Or maybe even a few rubber links spaced in the tread to help give a little resistance to sideways pushing.

Interesting idea. It'd be easy to put that setup on a steel cable around pullies and create the same effect as tank treads. At $3 per roller, 7 feet of belting is only $156 + the cable and shipping...comparatively cheap. Your other option is to use a full-length track of those and a separate short-track belt tread (that runs off the same transmissions) in the middle to provide resistance to sideways pushing.

I wonder what the initial expression on A/M's face would be when they see an order for 100 of these and no associated mecanum wheels

[UndergroundVoid]

Originally Posted by IndySam

I would love to do a tank design using links like a real tank and the rollers from an AM 6" mecanum wheel mounted sideways. Kind of like a omni tread. Or maybe even a few rubber links spaced in the tread to help give a little resistance to sideways pushing.

Hmm this would highly interesting i had have some ideas about this but didn't know if the effort would be to much or if the robot could be anything more than a push bot but, since i haven't done the measurement and only have done coffee napkins of this i wouldn't know what is possible. but i do know you would still have to obey the laws of mecanum with 4 individually power track (mecannum version) systems. now the only component i see that would be troubling is making those tracks but other than that the system would be simple. Also just thinking about it you could lower the inner wheels a little to get the turning a little bit better like the other track systems. If anyone plans to do this let me know. I know i will try again at it but whether or not i use it all depends but as far as i know no one else has done it.

[Dowjonesbotics]

im confused here for a sec...

I've heard when treads are used that people call it tank drive BUT when people use 6 wheels drive they also call it tank drive. What??