Vibration on arm

Lynxmotion Robot Arms
1

Hi everyone,

I have an L6.
I made a controller with PIC16F877 using PBP. I am controlling just 2 servos using PWM. (2nd axis, 3rd axis) This is for test, so other servos are unplugged.
And my problem:Arm is vibrating.
It stops vibration ~40 sec. then when i softly touch the gripper it starts to vibrating again.
I have controlling problem as seen but i couldn’t find where.
Pic runs with 4mhz osc, PWM freq is 250hz and 400 duty value positioning servos to center.

Can anyone help me about it?

2

You can’t use the PWM from a PIC to control servos. What you need is the following.

_______20mS_______|-----500uS to 2500uS----|_______20mS________

The pulses must repeat every 20mS. The range is 500uS to 2500uS for the positive going signal where 1500uS is centered.