i changed the (i < 30) to (i < 4), i thought this is what adjust the speed T-T
What else did you change?
as for the the problem of the none accurate of either one axis is due to the incoming data...in roborealm i sent both cog_x and cog_y to arduino so maybe it cant differentiate data of which is for pan and which is for tilt...any help ??
How? If you send two angles, 121 and 40, the serial stream would look like '1', '2', '1', '4', '0', unless you used some kind of separator. How is the Arduino supposed to decide if that is 12 and 140 or 121 and 40 or 1214 and 0 or 1 and 2140?
Telling half the story doesn't get you much help. We need the whole story.
as for the servo, is powered by connecting to the arduino 5v output...
Well, that's why your servo doesn't move very fast, then. It is severely underpowered. You need a separate power supply for the servo, matching the voltage expected by the servo, and capable of delivering the current that the servo needs.