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View Full Version : Controlling multiple servo motors.



yash25
01-20-2010, 07:20 PM
I am trying to control 6 servos simultaneously using an 8051 chip (P89V51RD2). However, I cannot control more than 3 servo motors at one time. As soon as I connect the 4th servo, all the other servos start behaving erratically..
1) Has anyone else faced such a problem. What could be the reason ( I am using three servos from vegakits and three are HS311)?
2) And has anyone successfully programmed 6 servos or more simultaneously? If so, please help!

rao
01-20-2010, 08:53 PM
I think your problem is power again.. dont try to run all 6 at once..think about how much current each pulls... is your power source strong enough? also keep your signal power and motor power seperate. By that I mean dont power your servos with the same battery which you would use to power your microcontroller with a 7805...

I would suggest you to go for one of those 16-32 servo controllers, they will make your life much easier and then all you have to worry about would be your programming part and servo positions..

P.S. All servos dont follow 1000ms to 2000ms pwms... there will be small differences.. try to find out what the exact end pwm frequencies are for your servos.

yash25
01-20-2010, 10:16 PM
Thank you Sir, for the quick reply.
Yes, even I think that power is the culprit here. But it is very important for me to power at least 4 servos simulataneously. The other two can be handled seperately.
1) Which battery can you suggest for achieving the above purpose?

2) Further,

also keep your signal power and motor power seperate. By that I mean dont power your servos with the same battery which you would use to power your microcontroller with a 7805...

Yes, that I can do. But supplying power to the same componant(servo motor) using two different supplies (i.e motor supply and signal power)? Won't this cause a ground problem? Or is there an isolater circuit inbuilt in a servo?

3) Also, the operating voltage of my servo is 6 V. So can you suggest a suitable signal power for my board, and a suitable motor power source?

4)
I would suggest you to go for one of those 16-32 servo controllers, they will make your life much easier and then all you have to worry about would be your programming part and servo positions..

Can you suggest something available in India? Or will I have to go for the lynxmotion boards?

5) Also, just asking, will a switching regulator be more efficient if I want to use the same power supply for both board and motor?

allbits
01-21-2010, 11:18 AM
Is it when you CONNECT the 4th servo, or is it when you PROGRAM for the 4rth servo that the error happens??

post the code.. FOr testing, use 4x1.5v battery !!

yash25
01-21-2010, 08:49 PM
Is it when you CONNECT the 4th servo, or is it when you PROGRAM for the 4rth servo that the error happens??

It's when I connect the servo..when the 4th servo is removed, the other three run smoothly.

rao
01-21-2010, 10:45 PM
Replying to your questions in the sequence you asked...

1.) I suggest NiCd 6V 2400mAH for the motors

2.) Use your basic off the shelf 9V battery for powering the microcontroller. Keep grounds common.

3.)Already answered

4.) I dont know about indian vendors but the Lynxmotion ssc-32 controller is WAAAAY BETTER than the parallax servo controller.

5.) For testing purposes... why not?? use batteries for final testing.

yash25
01-22-2010, 08:15 AM
I have currently managed to procure a 4500 mAh NiMH battery..I hope it will be enought to power all my servos..