Raspberry Pi Robotics
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Raspberry Pi Robotics

by rdbuchmann on Mon Feb 25, 2013 11:59 pm

Hi,
I just got a Raspberry Pi and an OWI Edge Robotic Arm. I would like to program Raspberry Pi to control the robotic arm to do simple tasks, like stacking dice. What PI accessories would i need to make this happen? I already have a Motorola Atrix dock with the micro USB y-cable, so really all I need is what is necessary to control the robot. Thanks for your help!
Ryan
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Re: Raspberry Pi Robotics

by adafruit_support_bill on Tue Feb 26, 2013 7:27 am

The first thing you need to do is to add feedback to the arm movement so you can control it. This instructable is for Arduino control, but the feedback pots he uses would also work for a Pi.
http://www.instructables.com/id/Intro-a ... oull-need/
Then you need to find some motor controllers for each of the 5 axis. Pololu makes some nice modular controllers that should work for this application. www.pololu.com.
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Re: Raspberry Pi Robotics

by tldr on Tue Feb 26, 2013 7:07 pm

might be more economical to make your own intelligent motor controller with an atmega32u4 breakout board and a handful of l293d's. if you run out of pins on the microcontroller you can throw in a couple of 595's and rig a super motor shield.

have a look at the motor shield schematic to see how to wire it all up. Image

the mega32u4 breakout has enough pwm outputs for 6 motors and enough a/d pins to sense their positions, but probably not enough pins left over for directional control for the motors, which is where the 74hct595s would come in. for 6 motors, you'll need two. the clock, latch, and enable inputs would be the same for both 595's, but pin 9 of the frist one would connect to the serial input, (DIR_SER) of the second one.
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Re: Raspberry Pi Robotics

by rdbuchmann on Fri Mar 01, 2013 2:15 am

The microcontroller option from Pololu looks appealing, but they have so many to choose from! They have robot controllers and programmable controllers. Is there a difference? And in the selection process, is there a buying guide? Granted, the description tells me what configuration I am getting in a board, but how do I tell if it will work for my application (controlling the robotic arm)? Do these microcontrollers require a shield, like the Aduino board does? I realize my "newbness" is flagrantly displaying now, but I really don't want to buy something that's insufficient or overkill. Thanks for the help!
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Re: Raspberry Pi Robotics

by adafruit_support_bill on Fri Mar 01, 2013 7:24 am

The motors in the OWI arm are pretty small, so you don't need any of the high-power controllers. The QIK motor controller has more than enough power. The Baby Orangutan robot controller also has enough power, plus sensor inputs and on-board intelligence for implementing feedback control.
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Re: Raspberry Pi Robotics

by rdbuchmann on Sat Mar 02, 2013 1:27 am

How does a Baby Orangutan compare to an Arduino board with a motor shield? It appears that both are capable of controlling the robot arm, but the Arduino board requires more hardware. Does the Baby Orangutan contain all that is necessary to control all of the motors (including claw) on the robot arm (the motor shield for the Arduino only controls 4 motors)?
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Re: Raspberry Pi Robotics

by adafruit_support_bill on Sat Mar 02, 2013 7:48 am

You need a total of 5 motor controllers for the OWI. The Adafruit Motor Shield has 4. The Baby Orangutan has 2. You would need 3 Orangutans to control all the motors on the arm.
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