Robot Arm C

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sachleen
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Re: Robot Arm C

Post by sachleen » January 16th, 2012, 2:14 pm

chalker wrote:
OldSpice wrote:
illusionist wrote:Is it legal to place a part of the robot inside one of the goals? For example, dropping a piece of tape in along with the PVC pipes.
If I remember correctly, yes it is legal, though you should submit a clarification yourself to be sure.

We've gotten several questions at soinc.org about this. And while this of course is not the place for official clarifications, please note rule 6.c.vii, which could be interpreted to mean that if anything becomes detached from the arm, time must stop.
Rule 6.c.vii specifically talks about the "Arm(s)" becoming detached from the optional base. The first line of the construction parameters says "an optional permanently attached Base." 3.a states "The Arm(s) may be attached to a Base." This leads one to the understanding that the "arm" is attached to the "base" which is touching the ground. Rule 4.a.iii differentiates between an "arm" and an "end effector," defining end effectors as "parts that interact with the items on the Competition Area."

Based on what I described above, I would argue against the interpretation you made.

On a another note, how would you guys interpret rule 6.c.v? Would any part of the arm (end effectors included) touching the ground be enough to cause the time to stop? (I would say "no")

Disclaimer: All of this is nothing more than my opinion. This is not a place for official rule clarifications.

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Re: Robot Arm C

Post by chalker » January 16th, 2012, 4:50 pm

sachleen wrote: Rule 6.c.vii specifically talks about the "Arm(s)" becoming detached from the optional base. The first line of the construction parameters says "an optional permanently attached Base." 3.a states "The Arm(s) may be attached to a Base." This leads one to the understanding that the "arm" is attached to the "base" which is touching the ground. Rule 4.a.iii differentiates between an "arm" and an "end effector," defining end effectors as "parts that interact with the items on the Competition Area."

Based on what I described above, I would argue against the interpretation you made.

On a another note, how would you guys interpret rule 6.c.v? Would any part of the arm (end effectors included) touching the ground be enough to cause the time to stop? (I would say "no")
First, standard caveat about this not being the place for official clarifications...... However, note, since I see all the Robot Arm question responses that go out from soinc.org (and help draft most of them), I already know that early in Dec we gave the response I alluded to above (we just didn't post it on the website, although I've suggested we do that now).

The logic we followed involved this: Section 3 describes the device as the Arm, optional Base, and control boxes. That means that from the rules standpoint, there are 3 main components. 4.b.iii. refers to "Arm end effectors", which explicitly indicates that the end effectors are PART OF the Arm (as opposed to being part of the base or the control boxes). 6.c.vii. talks about the Arm becoming detached from the base. While it doesn't say anything about parts of the Arm becoming detached, we interpreted that to mean the Arm as a whole or any part thereof.

Rule 6.c.v was put in place to prevent 'mobile' robot Arms. We didn't want this to turn into the old Robo Billiards event by having robots roam around and scoop things up.

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Re: Robot Arm C

Post by eta150 » January 16th, 2012, 5:40 pm

blue cobra wrote:
eta150 wrote:Solon got a perfect score at Athens. It was crazy
Was that with their robot with the master and slave system?
yeah, it was very impressive
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Re: Robot Arm C

Post by CoachMike » January 17th, 2012, 11:25 am

sachleen wrote: On a another note, how would you guys interpret rule 6.c.v? Would any part of the arm (end effectors included) touching the ground be enough to cause the time to stop? (I would say "no")
I would say this would be a ridiculously heinous interpretation of the rules. For the objects that are quite small like pencils and nails, moving the end effector close enough to the surface to pick them up without TOUCHING the surface with the tip of the effector would be QUITE difficult. To ask the olympian pilot to perform that operation up to 19 times without touching the play surface seems onerous and silly.

The seeming cause for 6.c.v is to prevent a robot from "driving off" to perform the task.

Rule 6.c.vii is more tricky. Chalker's interpretation of the rule prohibits any sort of depositable or otherwise removable specialized tool. I would note that REAL industrial robots do this all the time. Even a basic multiaxis CNC machine typically includes a rotary drum loaded with tools that it swaps in/out of the drive system to cut different profiles, measure starting positions, etc. Using an end effector in this competition which swapped out a magnet for a short rod (a good/easy tool for picking up the PVC sections) would be a violation according to Chalker's interpretation. This would seem to overly limit the creative ways in which the task can be accomplished and pretty much forces everyone to build some manner of general purpose gripper end effector. If that was the goal in the rulemaking, then it should have been stated in the task objective.

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Re: Robot Arm C

Post by Primate » January 17th, 2012, 7:08 pm

eta150 wrote:
blue cobra wrote:
eta150 wrote:Solon got a perfect score at Athens. It was crazy
Was that with their robot with the master and slave system?
yeah, it was very impressive
how many motors? i honestly can't envision anything competitive with any less than five
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Re: Robot Arm C

Post by hmcginny » January 17th, 2012, 9:06 pm

As far as I could tell it was only 4 motors. Solon's second team also had a nearly identical version of the arm, though the controls weren't calibrated perfectly and the base left the box accidentally or else they too would have had a perfect run.
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Re: Robot Arm C

Post by decfrv » January 18th, 2012, 8:08 pm

what kind of modifications would qualify for a VEX set? i dont really understand what has to be done to "modify" a vex set

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Re: Robot Arm C

Post by twototwenty » January 19th, 2012, 6:07 am

decfrv wrote:what kind of modifications would qualify for a VEX set? i dont really understand what has to be done to "modify" a vex set


I believe that, as vex kits aren't specifically robot arm kits and you would need to innovate to build a robot arm, the use of a vex kit for an arm would be no problem. After all, it does seem to be the most popular choice as far as building materials.
Primate wrote: how many motors? i honestly can't envision anything competitive with any less than five
It would be quite possible to build a sucessful arm with only three motors, as can be seen with this example:
http://www.youtube.com/watch?v=62HaAmbV ... afe=active

Does anyone know exactly how solon went about making the master-slave system/what materials they used?

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Re: Robot Arm C

Post by OldSpice » January 19th, 2012, 8:50 am

twototwenty wrote:
decfrv wrote:what kind of modifications would qualify for a VEX set? i dont really understand what has to be done to "modify" a vex set


I believe that, as vex kits aren't specifically robot arm kits and you would need to innovate to build a robot arm, the use of a vex kit for an arm would be no problem. After all, it does seem to be the most popular choice as far as building materials.
Primate wrote: how many motors? i honestly can't envision anything competitive with any less than five
It would be quite possible to build a sucessful arm with only three motors, as can be seen with this example:
http://www.youtube.com/watch?v=62HaAmbV ... afe=active

Does anyone know exactly how solon went about making the master-slave system/what materials they used?
Unfortunately I did not have the chance to see it, but I'd assume they used a microcontroller such as arduino and a series of potentiometers on the master arm. I tried doing something similar but I couldn't finish it in time for athens. It's a pretty tricky build.
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Re: Robot Arm C

Post by chalker » January 19th, 2012, 8:29 pm

twototwenty wrote: It would be quite possible to build a sucessful arm with only three motors, as can be seen with this example:
http://www.youtube.com/watch?v=62HaAmbV ... afe=active
Nice robot arm. Is that your team? If so, any rough idea of the cost of all the parts? We've been having a bit of a debate at the national level of how much it would cost to make a competitive arm (which that design seems to be).

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