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Author Topic: Need some help for a science project.  (Read 9886 times)
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What should it be powered by then?

Four 1.5v batterys in series would do for simplicity, like below.

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Did you have a look at DuaneB's servo tutorials as I suggested in post #3? They really do explain servos very clearly.
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Yes, I looked at the tutorials. I'm starting to understand the concept more.
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Yes, I looked at the tutorials. I'm starting to understand the concept more.

Cool.... for what it's worth my daughter's busy with a servo controlled arm... so far just a shoulder and an elbow. Shoulder is two standard servos on a pan and tilt bracket; elbow is a micro. It's mounted with Meccano (= Erector Set) in a small wooden box to stop it falling over and the upper and lower arm are Meccano too. Pic attached....


* servo arm.jpg (912.85 KB, 1552x2592 - viewed 28 times.)
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I got the wires and the breadboard yesterday.  smiley
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I just need to obtain a battery that can support all of these servo motors.
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I just need to obtain a battery that can support all of these servo motors.

Yep, and there's a lot of discussion about power supply on this forum!

I've just (literally yesterday) been given a 650W ATX PSU and using an Instructable like this we're converting that to a lab supply. The servos I have are happy at 5v, and I can also use the 5v to supply Uno through the USB. (Alternatively I might regulate that up to 7.x V with one of these (which I have) and feed that to the barrel or Vin).
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How many servo motors should I be using?
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How many servo motors should I be using?

Hey- glad you're making some progress!

I didn't read those hand instructions in any detail, but it seemed to me there's a string in each finger, is that right? Then I suppose at a maximum you would need a servo per finger. On the other hand (sorry about the pun), maybe you could gather the strings together and activate them with only one servo. Or somewhere in between- space and weight will be a consideration. You will need to experiment with that- that's part of the fun of this whole thing. I think too, that you'll need to experiment with servo positioning relative to the hand, to give the right angle when the strings are pulled, and build some kind of base for the whole thing.

Then you'll need to figure out how to attach the hand to the arm- the arm I showed has three servos: 2x standard size a "shoulder" in a pan / tilt bracket and 1x micro as an "elbow". Number of motors depends on the number of joints and the range of motions you need.

As an aside, I've asked my local supplier to see if he can source a pan / tilt bracket like that for micro servos: it would make a cool wrist.
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Is it possible to put these into a breadboard? http://www.amazon.com/SparkFun-Arduino-Stackable-Header-Kit/dp/B004G56J8W/ref=cm_cr_pr_product_top
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I would have thought so but what is the point. A breadboard is a pile of sockets, you just make some of them higher.
Those in the link are very expensive, an electronics distribuitors will have them cheaper.
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I have obtained all of the materials that I need for the hand.  smiley-grin Once the hand is completed (which should be tonight), where do the Arduino and the servo motors come in? Keep in mind that I'm still a beginner, and I don't know the ins and outs of robotics. Here are the articles if you're interested in reading them. http://www.sciencebuddies.org/science-fair-projects/project_ideas/Robotics_p003.shtml
http://www.sciencebuddies.org/science-fair-projects/project_ideas/Robotics_p001.shtml
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Have you tried uploading the example sketches?


My advice is to grab your Arduino and work through the simple examples on this site, such as good old Blink. Then grab a servo and a potentiometer and work through the two servo examples, namely Sweep and Knob.
I really think that to start, you have to get your mind how an Arduino program hangs together and how a servo is controlled.
Good luck!
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Example sketches of the hand?
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No. Upload the sketches in the photos linked.
http://flic.kr/p/dMX4Ri
http://flic.kr/p/dMX4RV
« Last Edit: January 19, 2013, 10:52:31 pm by arduinohabib » Logged

What is man's best friend? The breadboard!

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