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Topic: Need some help for a science project. (Read 11530 times) previous topic - next topic

Falchion

I decided to make a robotic hand out of simple materials (here is the project summary:http://www.sciencebuddies.org/science-fair-projects/project_ideas/Robotics_p003.shtml) and I need some help programming the fingers so I can get them to move. What I want it to do involves picking up a chess piece and placing it in its designated spot. I have very little programming experience, and I would greatly appreciate it if you could explain it in basic terms.  :)
Robots are cool.

JimboZA

#1
Jan 07, 2013, 06:04 am Last Edit: Jan 07, 2013, 06:15 am by JimboZA Reason: 1
Wow this is a biggy for a starting point..... but nothing quite like jumping in the deep end!

That site says:

Quote
Once you have your robot hand


which makes that part sound pretty simple. Have you got that far yet?- ie the mechanical part?

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.

First Things First....

Edit... by the way, to get the hand to move to a point is more than just building and programming the hand. A hand, to be useful, needs to be on an arm, that's another 4-5 servos and some fairly major construction. Not to mention the logic and sensing involved in knowing where QB4 is on the board....
My hovercraft is full of eels.

No PMs for help please.
DO NOT power servos from Arduino 5V: give them their own power and connect the grounds.

Falchion

I almost have the fingers done. Thank you for the advice though. Also, how do you get the wires out of the servo motor? I'm using the Futaba S3003 servo motors if that helps.
Robots are cool.

JimboZA

#3
Jan 07, 2013, 07:15 am Last Edit: Jan 07, 2013, 07:21 am by JimboZA Reason: 1
Quote
how do you get the wires out of the servo motor


Not sure what you mean...

There is usually a three wire connection coming out of a servo into a small plug with holes for 3 connectors- usually red and black for 5v and ground, and yellow or orange for the control. You need to stick wires (preferably with pins on the end) into those sockets and take them to the power supply and Arduino pin. You can see the 3 way plug clearly in this pic of your servo.

You may find that standard size servo a bit big especially if you have 5 of them next to each other. Might be an idea to consider a micro servo like this.

Edit.... you should have a look at DuaneB's acclaimed servo tutorials here and here.
My hovercraft is full of eels.

No PMs for help please.
DO NOT power servos from Arduino 5V: give them their own power and connect the grounds.

Falchion

I got the red wire out successfully, and when I put it into 5V, it felt pretty loose. Is it supposed to feel that way?
Robots are cool.

AWOL

Quote
I got the red wire out successfully, and when I put it into 5V, it felt pretty loose. Is it supposed to feel that way?

I'm really not sure what you're saying here.
"Pete, it's a fool looks for logic in the chambers of the human heart." Ulysses Everett McGill.
Do not send technical questions via personal messaging - they will be ignored.

wildbill


I got the red wire out successfully, and when I put it into 5V, it felt pretty loose. Is it supposed to feel that way?


Note that the arduino can sometimes, depending on the servo, just about manage to power one. For the multiple ones you're going to need, you'll need a separate power supply for the servos. DuaneB's tutorials mentioned above should help you with how to wire them up.

Falchion

Is this what its supposed to look like when you take the wire out?
Robots are cool.

wildbill

#8
Jan 07, 2013, 11:49 pm Last Edit: Jan 08, 2013, 12:00 am by wildbill Reason: 1
Why did you remove the wire from the socket? What do you intend to attach it to?

edit: typo

Falchion


Why did you remove the wire from the socket? What do you intent to attach it to?
The 5V port on the Arduino. Did I do something wrong?  :~
Robots are cool.

wildbill

Well normally at this stage of your project, you'd be more likely to use some breadboarding wire to stick into the servo's socket and then attach those wires to whatever is going to power the servo - which should not be the arduino - it can't provide sufficient current for more than one, if that.

Later you might wire it up using a male connector into the servo's socket so that it's easier to replace the servo from your robot if it is damaged, or solder it all together if you decide you don't need that luxury.

Falchion

So I need to buy these wires to plug them into the sockets?
Robots are cool.

Grumpy_Mike

At the very least yes. You actually need to get a pin header and solder the wires from the servo to it.

Falchion


Well normally at this stage of your project, you'd be more likely to use some breadboarding wire to stick into the servo's socket and then attach those wires to whatever is going to power the servo - which should not be the arduino - it can't provide sufficient current for more than one, if that.

Later you might wire it up using a male connector into the servo's socket so that it's easier to replace the servo from your robot if it is damaged, or solder it all together if you decide you don't need that luxury.
What should it be powered by then?
Robots are cool.

wildbill

For initial experiments, I searched around my house for an old wallwart in the right range - 6-7 volts IIRC. The ones I found didn't provide enough current for more than a couple of servos though. You may need to buy (or build) something that provides more juice. Even though your robot sounds like it will be stationary, you might look at lipo batteries to avoid the need for acquiring what would effectively be a beefier wallwart.

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