Robot Arm C

Locked
User avatar
harryk
Exalted Member
Exalted Member
Posts: 268
Joined: March 17th, 2010, 12:28 pm
Division: Grad
State: TX
Has thanked: 0
Been thanked: 0

Re: Robot Arm C

Post by harryk »

ichaelm wrote:First of all, I just want to say that I'm impressed by the amount of useful discussion in this thread! I noticed that in my team, at least a third of all our new freshmen intend to do Robot Arm, since the idea of building robots must appeal to a lot of people. Looks like that happened around the country too!

One thing I've been wondering about is the definition of a motor. I intend to submit a clarification as soon as possible, but until then, I'll post here. Obviously, a rotating axle powered by electromagnets is a motor. But, what about just a permanent magnet that can be moved by an electromagnet, in a linear way? Or what about a piece of ferrous metal moved by an electromagnet? Or an electromagnet that can pick up nails? All of those add a degree of freedom to the robot, but I doubt that all of them count as motors.
Well yes, the definition of a motor could include many different devices, but I'm assuming they were intending the definition as a "axis rotated by the input of electrical energy"
Go ahead and submit a clarification, because there is probably some really persnickety regional judge who would give people a hard time
Colorado School of Mines
"Yes, he likes that; Alfie! Though personally he prefers to be called Stormaggedon, Dark Lord of All" - The Doctor, Closing Time
User avatar
ichaelm
Member
Member
Posts: 440
Joined: October 23rd, 2008, 3:10 pm
Division: Grad
State: PA
Has thanked: 0
Been thanked: 0
Contact:

Re: Robot Arm C

Post by ichaelm »

Yeah, I wouldn't have thought about it except that this year they included hydraulic and pneumatic motors, which I assume was meant to count air cylinders and hydraulic cylinders, but neither of those are rotary.
chalker7
Member
Member
Posts: 612
Joined: September 27th, 2010, 5:31 pm
Division: Grad
State: HI
Has thanked: 0
Been thanked: 1 time

Re: Robot Arm C

Post by chalker7 »

ichaelm wrote:First of all, I just want to say that I'm impressed by the amount of useful discussion in this thread! I noticed that in my team, at least a third of all our new freshmen intend to do Robot Arm, since the idea of building robots must appeal to a lot of people. Looks like that happened around the country too!

One thing I've been wondering about is the definition of a motor. I intend to submit a clarification as soon as possible, but until then, I'll post here. Obviously, a rotating axle powered by electromagnets is a motor. But, what about just a permanent magnet that can be moved by an electromagnet, in a linear way? Or what about a piece of ferrous metal moved by an electromagnet? Or an electromagnet that can pick up nails? All of those add a degree of freedom to the robot, but I doubt that all of them count as motors.
Not an official clarification, but my two cents. I dread citing dictionaries and online references, however most definitions of "motor" simply claim a device that creates mechanical motion, without specific direction or type (ie, left/right, in/out, rotational/linear).
National event supervisor - Wright Stuff, Helicopters
Hawaii State Director
twototwenty
Exalted Member
Exalted Member
Posts: 292
Joined: March 24th, 2011, 10:28 am
Division: Grad
State: NY
Has thanked: 0
Been thanked: 0

Re: Robot Arm C

Post by twototwenty »

Someone said the area is 15% smaller this year. I dont have my rules yet, so what are the exact dimensions of the track?
User avatar
ichaelm
Member
Member
Posts: 440
Joined: October 23rd, 2008, 3:10 pm
Division: Grad
State: PA
Has thanked: 0
Been thanked: 0
Contact:

Re: Robot Arm C

Post by ichaelm »

chalker7 wrote:
ichaelm wrote:First of all, I just want to say that I'm impressed by the amount of useful discussion in this thread! I noticed that in my team, at least a third of all our new freshmen intend to do Robot Arm, since the idea of building robots must appeal to a lot of people. Looks like that happened around the country too!

One thing I've been wondering about is the definition of a motor. I intend to submit a clarification as soon as possible, but until then, I'll post here. Obviously, a rotating axle powered by electromagnets is a motor. But, what about just a permanent magnet that can be moved by an electromagnet, in a linear way? Or what about a piece of ferrous metal moved by an electromagnet? Or an electromagnet that can pick up nails? All of those add a degree of freedom to the robot, but I doubt that all of them count as motors.
Not an official clarification, but my two cents. I dread citing dictionaries and online references, however most definitions of "motor" simply claim a device that creates mechanical motion, without specific direction or type (ie, left/right, in/out, rotational/linear).
That definition seems logical, but it has some weird consequences. Is a permanent magnet a motor, just because it can cause a nail to move? That question would lead to the modified definition, just for the purposes of this event: a device that does mechanical work, and is powered by electrical, hydraulic, or pneumatic means. This excludes permanent magnets, but it includes air cylinders and hydraulic cylinders, which is the purpose of the rule. But it also includes electromagnets. I can't think of any reason why an electromagnet would ever be called a motor, except for the purposes of the rule. Was the intention of the rule to include electromagnets designed to pick up nails? If so, then using the source-of-energy definition suits it well. Otherwise, you need a more complicated definition I haven't thought of. But again, that is also just my two cents!
twototwenty wrote:Someone said the area is 15% smaller this year. I dont have my rules yet, so what are the exact dimensions of the track?
70 cm square.
jander14indoor
Member
Member
Posts: 1653
Joined: April 30th, 2007, 7:54 am
Has thanked: 0
Been thanked: 29 times

Re: Robot Arm C

Post by jander14indoor »

Again, NOT the place for clarifications.

But in the spirit of reasoned discussion.

I think you've got most of the items understood ichaelm. I don't think a permanent magnet would meet the definition of a motor in this case because it isn't changing any input to a mechanical output, unless you consider the mechanical act of putting the magnet near an object, but that's mechanical to mechanical.

But on your electro magnet, I think the devil is in the details. For a straight electromagnet there isn't necessarily a mechanical energy output.
- One case. The arm locates the electromagnet next to a nail. Actuate the magnet locking the nail onto it, but nothing moves. Then the arm moves the whole thing to a goal box. No transformation of electrical to mechanical motion by the electromagnet in that case. The motors on the arm did that!
- Second case. This time the electromagnet is located at a distance from the nail by the arm. Electromagnet turns on and the nail is pulled to the magnet over a distance. Mechanical motion, you have a 'motor' again.

One view.

Jeff Anderson
Livonia, MI
chalker7
Member
Member
Posts: 612
Joined: September 27th, 2010, 5:31 pm
Division: Grad
State: HI
Has thanked: 0
Been thanked: 1 time

Re: Robot Arm C

Post by chalker7 »

jander14indoor wrote:Again, NOT the place for clarifications.

But in the spirit of reasoned discussion.

I think you've got most of the items understood ichaelm. I don't think a permanent magnet would meet the definition of a motor in this case because it isn't changing any input to a mechanical output, unless you consider the mechanical act of putting the magnet near an object, but that's mechanical to mechanical.

But on your electro magnet, I think the devil is in the details. For a straight electromagnet there isn't necessarily a mechanical energy output.
- One case. The arm locates the electromagnet next to a nail. Actuate the magnet locking the nail onto it, but nothing moves. Then the arm moves the whole thing to a goal box. No transformation of electrical to mechanical motion by the electromagnet in that case. The motors on the arm did that!
- Second case. This time the electromagnet is located at a distance from the nail by the arm. Electromagnet turns on and the nail is pulled to the magnet over a distance. Mechanical motion, you have a 'motor' again.

One view.

Jeff Anderson
Livonia, MI
I would agree with Jeff in an completely unofficial context.
National event supervisor - Wright Stuff, Helicopters
Hawaii State Director
chalker
Member
Member
Posts: 2107
Joined: January 9th, 2009, 7:30 pm
Division: Grad
State: OH
Has thanked: 1 time
Been thanked: 56 times

Re: Robot Arm C

Post by chalker »

chalker7 wrote: I would agree with Jeff in an completely unofficial context.
And I would officially agree with my brother's unofficial agreement;)

Just want to make sure everyone is keeping this in perspective. Motor count ONLY comes into play as a tiebreaker. Obviously our intention when writing the rules was to 'reward' teams that are able to 'do more with less'. The thought being it's much harder to engineer and efficiently operate a device that has less 'ways to move'. Thus for all you trying to figure some way around the specific wording, please keep in mind the spirit of our intent.

Of course this is all unofficial, however we've already started to have some internal committee conversations about this. I strongly encourage someone to submit a question at soinc.org so that we can formally respond there.

Student Alumni
National Event Supervisor
National Physical Sciences Rules Committee Chair
User avatar
Primate
Member
Member
Posts: 409
Joined: January 15th, 2009, 4:34 pm
Division: C
State: NY
Has thanked: 0
Been thanked: 0

Re: Robot Arm C

Post by Primate »

chalker wrote:
chalker7 wrote: I would agree with Jeff in an completely unofficial context.
And I would officially agree with my brother's unofficial agreement;)

Just want to make sure everyone is keeping this in perspective. Motor count ONLY comes into play as a tiebreaker. Obviously our intention when writing the rules was to 'reward' teams that are able to 'do more with less'. The thought being it's much harder to engineer and efficiently operate a device that has less 'ways to move'. Thus for all you trying to figure some way around the specific wording, please keep in mind the spirit of our intent.

Of course this is all unofficial, however we've already started to have some internal committee conversations about this. I strongly encourage someone to submit a question at soinc.org so that we can formally respond there.
Done. Let us know what you decide!
events 2012 gravity vehicle, robot arm, thermodynamics, tps
User avatar
illusionist
Member
Member
Posts: 942
Joined: March 20th, 2010, 4:13 pm
Division: C
State: MI
Has thanked: 0
Been thanked: 1 time

Re: Robot Arm C

Post by illusionist »

A cheap and plausible solution for most teams:
Using two Lego NXT Mindstorms sets, it's possible to create a master-slave system. Although there might be some lag between input and output (I don't think it'll be significant at lower levels). You might end up using 6 motors, but I think it offers a pretty decent solution.

Does anyone have experience with a robot arm that is of similar dimensions to this year's created from Legos? I'm thinking that it might be a little heavy and clumsy though.
Locked

Return to “2012 Build Events”

Who is online

Users browsing this forum: No registered users and 1 guest