Robot Arm C

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mrsteven
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Re: Robot Arm C

Post by mrsteven » April 30th, 2012, 2:29 pm

Can you elaborate a bit on the "master slave" system? I've read some posts on here about it but nothing descriptive where I could get an image...
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Re: Robot Arm C

Post by ohiostar » April 30th, 2012, 3:19 pm

Can you elaborate a bit on the "master slave" system? I've read some posts on here about it but nothing descriptive where I could get an image...
http://www.youtube.com/watch?v=xrOhlBN-_ao

This would be a good example of the style controller refered to as Master/Slave.

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Re: Robot Arm C

Post by mrsteven » April 30th, 2012, 3:23 pm

Gotcha. That looks sweet, I've got to learn about that

Heres a question that seems maybe too obvious... but why aren't people just hooking up their bots to a computer program, going through the motions and capturing it on code then just having the bot go through the motions in competition sped up for the 3 minute time limit off of the program instead of controls?
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Re: Robot Arm C

Post by illusionist » April 30th, 2012, 3:39 pm

In relation to mrsteven's question, why aren't teams that have the capability to create a master-slave system just pre-programming their arms to run a sequence? It eliminates the human controller issue from the event. Plus, you are allowed to measure the playing field to ensure that each object is where it's supposed to be, so that's not an issue.
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Re: Robot Arm C

Post by mrsteven » April 30th, 2012, 3:54 pm

exactly what I think, I'm going to try that next year as this one my big thing wasn't rob arm but next year I'm focusing on it under a microscope
this way its a perfect run almost every time (for the occasional mismeasurement).

Although the Master/slave (is there a real name for this?) is a really cool idea that I'm going to implement in another on going project Im working on. I can't really find anything on it, this is why I'd like the actual name for it so I can make something like it for my robotics class project, but with R/C planes
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Re: Robot Arm C

Post by Jdogg » April 30th, 2012, 4:02 pm

One of the reasons that we didn't pre-program the arm to do the event for us, is that sometimes (once in a blue moon) orientation of goals or bonus jug can slightly change when a object is placed into it. Such as dropping the pencil into the milkjug can cause it to slightly move, then when the pvc pipe is attempted to be placed into the jug based on automation, the pvc pipe hits the edge of the milk jug and lands out of bounds. Programming something to do something is never perfect, maybe it might be an object that's skewed or the entire robot that's skewed or maybe even the motors cant replicate the exact locations every time. Essentially there is still uncertainty in pre-programming the arm, I'd say that it could be more catastrophic by causing one error after another once one coordinate is slightly off, which is greatly different than missing just one pencil or one pvc pipe.
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Re: Robot Arm C

Post by mrsteven » April 30th, 2012, 6:45 pm

Rather than, binding the containers first. Have a wood outline that you place the 3 goals in so they cant move prior to starting to place items in it, itll take up an extra 15 seconds but if preprogrammed you can do with no error so 2:45 should be sufficient to do the lifting motions? I'm unsure. Something to play with over the summer when I get a legit robotics set up

The master-slave idea I absolutely love. I really need to play with this for no other reason than fun. Where did you get the hardware/software for this? If you don't wish to post on the forums possibly PM me? I'm not going to nats so its not like I'm competition lol

This is a really cool idea
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Re: Robot Arm C

Post by chalker » April 30th, 2012, 7:56 pm

mrsteven wrote:
Although the Master/slave (is there a real name for this?) is a really cool idea that I'm going to implement in another on going project Im working on. I can't really find anything on it, this is why I'd like the actual name for it so I can make something like it for my robotics class project, but with R/C planes
Try this: http://en.wikipedia.org/wiki/Master-slave_manipulator

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Re: Robot Arm C

Post by chalker » April 30th, 2012, 7:58 pm

illusionist wrote:In relation to mrsteven's question, why aren't teams that have the capability to create a master-slave system just pre-programming their arms to run a sequence? It eliminates the human controller issue from the event. Plus, you are allowed to measure the playing field to ensure that each object is where it's supposed to be, so that's not an issue.

Pre-programming is a significantly more complicated step. Master-slave systems actually are rather simple to create from an electronics standpoint and don't even require a microprocessor (thus there isn't even anything to 'program').

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Re: Robot Arm C

Post by iwonder » April 30th, 2012, 8:41 pm

I don't quite grasp how you can do a master/slave system without some form of a microcontroller... If you use rc hobby servos you need one to generate the PWM to drive to servos, and if you had straight gearmotors you would need position feedback from both arms and a processor to run the control loop to position the arm... is there something simple I'm missing?
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