Servos jerking around!

[roineust]

Hello!

I am building a project, that includes an Arduino pro-mini 5V, a small, but relatively strong, slot-car 12V ~5A DC motor and 6 servos.

My problem is, that when the DC motor is working, the servos start jiggling and jerking and not going exactly in their programmed path. I have used a 4000mAh 30C battery, so i think it can not be the battery current capacity.

Can you help me solve this please?

P.S.
Someone just told me, that it might be an issue of noise reduction, because of the disturbance emitted by the DC motor.
If this is indeed the most probable cause, what is the easiest way for a layman to add noise reduction to the circuitry?

P.S2
When i had the exact same configuration, but with 2 servos, instead of 6 and an Arduino Uno, instead of an Arduino pro-mini, there was no problem.

Thanks!

 

[chuckey]

Loop the motor wires through a ferrite core with as many turns as you can, with .1 MF capacitor each side of it between the wires. Also connect a .01 MF capacitor directly from each brush holders to the motor frame. Make sure that the motor circuit wiring (high current) goes directly to the battery (it should be twisted). Any low power wiring (receiver, servos etc.) should have their own wiring back to the battery and not share any motor wiring . A additional 100 MFD capacitor at the receiver end of its power feed could help.
Frank

 

[roineust]

Frank,
By brush holders, do you mean the DC motor +(red) and ground (black) outputs?

 

[Audioguru]

The elevator, rudder and aileron servos in my electric RC airplanes normally jiggle and jerk because they use gyros/accelerometers to keep stability even when the air is turbulent.

 

[chuckey]

If your motor has the two wires hanging out of them, then its difficult. The length of these leads to the capacitors (back to the motor case) will act as aerials. The problem also is that it might not be a cure, but it is certainly a precaution a production machine would have. I have a thought, can you actuate your motor without the receiver being involved?, its that the jigging about might be a spurious output from the receiver because its picking up the brush sparking RF noise or it could be due to the big motor currents putting spurious voltage on the power line. If you can split the receiver output wires, to try and find out where the problem is coming from. Incidrntly , the dual .1 MF capacitors will help to reduce both the above effects.
Frank