how much equipment needed for robot arm control?
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how much equipment needed for robot arm control?

by kgraf on Fri Nov 16, 2012 4:36 pm

senior design project need to add sensors (gyro, tilt, accel) on a human operator's arm to drive an owi

535 robot arm edge in motion tracking master-slave arrangement. Can you recommend sensors,

microcontroller,etc.? The owi has 5 motors driven from an 8 pin flat ribbon cable currently connected

to a manual controller box. current budget is about $250 for control electronics.
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Re: how much equipment needed for robot arm control?

by adafruit_support_bill on Sat Nov 17, 2012 7:20 am

The ADS335 3G/3-axis accelerometer will handle both tilt & acceleration in 3 axis. http://www.adafruit.com/products/163
The L3GD20 3-axis gyro will give you the angular motion measurements: https://www.adafruit.com/products/1032
To control 5 motors and stay within budget you will probably need to roll-your-own controller with some H-bridge chips: https://www.adafruit.com/products/807
Or some of the driver carrier boards from Pololu: http://www.pololu.com/catalog/category/11
You will need about 20 digital pins to run them all, so an Arduino Mega would be a good microcontroller to use. https://www.adafruit.com/products/191
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Re: how much equipment needed for robot arm control?

by kgraf on Sat Nov 17, 2012 11:03 am

this is a two term project - to get started I would like to connect an angular sensor to drive the base motor on the owi 535 - just slide the sensor back-and-forth laterally and observe the arm base rotation response.

is this sufficient equipment?
1 L3GD20 3-axis gyro will give you the angular motion measurements: https://www.adafruit.com/products/1032

1 Arduino Mega would be a good microcontroller to use. https://www.adafruit.com/products/191

1 H-bridge chips: https://www.adafruit.com/products/807

Also, the connection into the arm is an 8 pin flat ribbon cable with a 21mm x 5mm box end connector (female) - do you have tools or cables or connectors to recommend? The arm currently works by simple double-pole mechanical switches that connect each motor to either a plus or minus 3 volts for cw/ccw rotation.

Do I need any software other than the Arduino ide?
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Re: how much equipment needed for robot arm control?

by adafruit_support_bill on Sun Nov 18, 2012 10:56 am

I would like to connect an angular sensor to drive the base motor on the owi 535 - just slide the sensor back-and-forth laterally

I'm not sure I understand. " back-and-forth laterally" implies linear motion. For that you would need the accelerometer instead of the gyro.

Do I need any software other than the Arduino ide?

We have a library for the Gyro sensor: https://github.com/adafruit/Adafruit_L3GD20
No library is needed for the accelerometer.
There are many code examples on the web for motor control with the L293D. Here is one: http://www.arduino.cc/playground/Main/D ... WithAL293D
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Re: how much equipment needed for robot arm control?

by kgraf on Sun Nov 18, 2012 11:36 am

Thank you for your response,
I would like to purchase the components from adafruit needed to get started.
I meant back-and-forth simulating a sensor gyro or accel on the human-operator's arm, located approximately on the bicep near the should rotating the base of the robot arm. Do you recommend an accel or gyro for the actual sensor located on the human-operator's arm. Should I have a gyro/accel for both horizontal and vertical rotation of the shoulder-to-elbow linkage?

Does the arduino mega allow for future upgrade to wireless operation?

The arm is currently powered by 4 'D' cell batteries and the mechanical double-pole switches - does
the current/voltage to the motors have to be directly driven from the mega and H-bridge chips
https://www.adafruit.com/products/807 doesn't recommend for 3V motors (which I have)
"Good for motor voltages from 4.5V up to 36V! This wont work well for 3V motors. The motor voltage is separate from the logic voltage."

Do you have any suggestions for connecting to the arm through the 8 pin flat ribbon cable or directly to the 8 pin connector on the arm?
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Re: how much equipment needed for robot arm control?

by adafruit_support_bill on Sun Nov 18, 2012 12:56 pm

Do you recommend an accel or gyro for the actual sensor located on the human-operator's arm.

The gyro would work in that configuration.
Should I have a gyro/accel for both horizontal and vertical rotation of the shoulder-to-elbow linkage?

The module is a 3-axis gyro, so only one module would be needed for the full range of motion.
Does the arduino mega allow for future upgrade to wireless operation?

There are several wireless options. We stock the XBee radios: http://www.adafruit.com/category/29

Inexpensive low-voltage DC motors can be tricky to control. But the ones in the OWI arm are better than most and respond well with the shield. See this instructable for how to connect the shield to the arm:
http://www.instructables.com/id/Intro-a ... oull-need/
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Re: how much equipment needed for robot arm control?

by kgraf on Sun Nov 18, 2012 5:43 pm

Thank you for the info. I learned a lot already - the motors are being driven directly from the motors
to the motor shield and the ribbon cable connector is bypassed. At least for now this solves connecting through the ribbon cable connector.

I am looking at a part from pololu http://www.pololu.com/catalog/product/2130 drv8833 that claims to
"deliver 1.2 A per channel continuously (2 A peak) to a pair of DC motors. With an operating voltage range from 2.7 to 10.8 V" it only costs $7 and would suffice for one motor rotating the base. Do you think it a better idea than 3) An Adafruit Motor Shield ($19.50) ? I will have to drive all 5 motors eventually - the instructable says the motor shield only drives 4 motors.

Is this an acceptable choice for the gyro?
1 L3GD20 3-axis gyro will give you the angular motion measurements: https://www.adafruit.com/products/1032

Is this an acceptable choice for the microcontroller - does it include future wireless compatibility?
can handle 3 to 4 input sensors (2 or 3 gyros and a pressure sensor to close gripper) and 5 motor control signals output?
1 Arduino Mega would be a good microcontroller to use. https://www.adafruit.com/products/191
Arduino Mega 2560 R3 (Atmega2560 - assembled) - Mega! do the XBee radios just plug in?

Is this enough to get me started - gyro, mega, drv8833? do I need any battery power supplies to power the arduino?

do you also recommend:
Premium Female/Female Jumper Wires - 40 x 6" - $6.95
https://www.adafruit.com/products/266
Extra-long break-away 0.1" 16-pin strip male header (5 pieces) - $3
http://www.adafruit.com/products/400


6) Some jumper wires ($6) and pin headers ($7.50)
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Re: how much equipment needed for robot arm control?

by adafruit_support_bill on Mon Nov 19, 2012 9:00 am

I am looking at a part from pololu http://www.pololu.com/catalog/product/2130 drv8833 that claims to
"deliver 1.2 A per channel continuously (2 A peak) to a pair of DC motors. With an operating voltage range from 2.7 to 10.8 V" it only costs $7 and would suffice for one motor rotating the base. Do you think it a better idea than 3) An Adafruit Motor Shield ($19.50) ? I will have to drive all 5 motors eventually - the instructable says the motor shield only drives 4 motors.

I'm sure the Pololu driver will work. I don't know what library support there is for it. You would have to ask Pololu about that.

Is this an acceptable choice for the gyro?
1 L3GD20 3-axis gyro will give you the angular motion measurements: https://www.adafruit.com/products/1032

Yes.

Is this an acceptable choice for the microcontroller - does it include future wireless compatibility?
can handle 3 to 4 input sensors (2 or 3 gyros and a pressure sensor to close gripper) and 5 motor control signals output?
1 Arduino Mega would be a good microcontroller to use. https://www.adafruit.com/products/191
Arduino Mega 2560 R3 (Atmega2560 - assembled)

Yes, The Mega should handle all that. The Gyro is a 3-axis gyro, so you only need one module to handle the full range of motion.

do the XBee radios just plug in?

No, you need XBee adapters to interface them to 5v devices like the Mega. http://www.adafruit.com/products/126

do you also recommend:
Premium Female/Female Jumper Wires - 40 x 6" - $6.95
https://www.adafruit.com/products/266
Extra-long break-away 0.1" 16-pin strip male header (5 pieces) - $3
http://www.adafruit.com/products/400

Yes, those are a good choice.
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Re: how much equipment needed for robot arm control?

by kgraf on Mon Nov 19, 2012 11:55 am

Thank you for your help,
purchased one of each: Order Number is: 198436

Are there any things you can recommend for accessories? like serial adapter cables? usb adapters?
do I need a 3 Volt power supply battery pack to drive the motors? what is the 'library support' you refer to for the motor driver drv8833?

I have arduino software installed in win 7. I've done some embedded asm language programming in the EE course lab, but nothing with robotics and arduino's. Do you recommend any s/w,tutorial or reference sources?
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Re: how much equipment needed for robot arm control?

by adafruit_support_bill on Mon Nov 19, 2012 12:33 pm

A standard USB cable will be sufficient to communicate between your computer and the Mega.
do I need a 3 Volt power supply battery pack to drive the motors?

There is about a 1.2v drop through the drive transistors in the L293D H-bridge chips. For 3v motors, you will want a power supply in the 4v to 4.5v range.
what is the 'library support' you refer to for the motor driver drv8833?

Adafruit provides an Arduino library to simplify programming for our motor shield. I don't know if Pololu has any software for their motor drivers.
Do you recommend any s/w,tutorial or reference sources?

Ladyada's Arduino tutorials are a good place to start. http://www.adafruit.com/tutorials
We also have specific tutorials for most of our products (The gyro tutorial should be ready soon). Just follow the links in the product description.
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Re: how much equipment needed for robot arm control?

by kgraf on Mon Nov 19, 2012 6:42 pm

how does the motor driver work? I need +/- 3V for cw/ccw rotation. How do I get both plus
and minus voltage out of the motor driver?
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Re: how much equipment needed for robot arm control?

by adafruit_support_bill on Tue Nov 20, 2012 7:09 am

The board uses an H-Bridge for each motor channel.
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Re: how much equipment needed for robot arm control?

by kgraf on Tue Nov 20, 2012 9:44 pm

Do you know anywhere on the web I can find a schematic or wiring diagram showing a gyro connected to an arduino connected to a motor driver and/or motor? I haven't been able to find a sensor-> processor-> actuator schematic.
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Re: how much equipment needed for robot arm control?

by adafruit_support_bill on Tue Nov 20, 2012 10:23 pm

I searched "arduino gyro robot arm control" and got a bunch of interesting hits.
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Re: how much equipment needed for robot arm control?

by kgraf on Wed Nov 21, 2012 12:20 pm

Your search choice is much better than gyro+arduino+motor+wiring diagram

I can't log into my account to check my order status
Order Number is: 198436
Is this because I paid through paypal?
How can I find out if my order has shipped?
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