Using an array to assign multiple servos' positions

Projects Programming
1

Please note that I am a novice and do not have a whole lot of experience with arduino.

So I am trying to set the position of multiple servo motors to their designated positions. In order to make it more efficient, I am using a for loop and an array of positions. I am testing this concept with two servos before I test it with more. For some reason, none of the servos will go to their correct orientations. It was just working not too long ago. Here is the code:

#include <Servo.h>
Servo servos[2];
int positions[]={90,90};

void setup() {
  for (int i; i<2; i++){
    servos[i].attach(i+11);
  }
  for (int i; i<2; i++){
    servos[i].write(positions[i]);
  }
}

void loop() {
}

Here's a link to a picture of the circuit in case I did something stupid: IMG_1285.JPG - Google Drive

2

OP's image

It's hard to tell what's connected to what.
Better to draw out a circuit - clearly separating power sources etc...

REMEMBER you cannot supply the servo +V from the Arduino!
It looks like your power supply goes straight into the Arduino - then out to the breadboard.

The servos require more than the board can supply, an dit will becoem 'dirty' as the servos operate - hence must be isolated from the logic on the cpu board.

3

lastchancename:
hence must be isolated from the logic on the cpu board.

Okay... I'm going to end up using about 36 servos (I know, it's a lot) so do you have any recommendations for adequate power supplies?

4

Well, you'll need to ensure the GROUND / 0V are all common
Then possibly break the servos into groups (so the power supply isn't huge).

Let's agree we are talking about RC style servos.. !

Say... each group of six servos is connected to a *single power supply, while the control wire still goes back to the Arduino servo control pins.

  • the rating of each cluster power supply depends on the type of servos, and the current requirement (mA or A) for the cluster of (six) servos.

e.g. 6 servos x 1.5A = 9A supply
or 6 servos x 500mA = 3A supply

Note that servos can draw MORE power if they are under load or 'stalled'.

5

Alright cool. How would I change the current in each cluster?

6

Depending on the type of servos, and type of power supplies that you have available.
The simple calculations above make it easy.

Big servos most probably use more power (Volts x Amps)
Big power supplies get more expensive - hence the suggestion of clusters or groups that can be powered independently.

7

I'm going to end up using about 36 servos

How will you be controlling that many servos ?

8

The big question for the size of the PSU is, how many will move at the same time?

9

Remember RC servos will draw current when stopped - more if they are holding a load.

10

True, should have included that.

So, how many servo's will move at the same time and do servo's need to apply a holding force?

11 
  for (int i; i<2; i++){
    servos[i].attach(i+11);
  }

The first part of a for loop is the initialization section. This statement says "Starting with i equal to whatever value is present in the memory address referenced by i, while i is less than 2, do something, and then increment i.

Surely, THAT is not what you intended. If it was, you should be pursuing other interests. A career as a programmer is not in your future.

12

Hehe -
I was looking past that.
There are more fundamental issues to be addressed!
Observation acknowledged!

13

I was looking past that.

When the compiler reports problems, where in the list do you start fixing things? I get better results when I start at the top. I fix one issue, and try again.

I look at code the same way. I see something obviously stupid, and I don't even read what the poster thinks the problem is.