regarding  speed of continous rotation servo motor

hello , i m working on autonomous robot. i m using two continuous rotation servos which are centered for 1500 microseconds. to move this robot in forward direction we have to give larger pulse than 1500 for right servo and pulse less than 1500 for left servo. wheels are attached to these two servos. following is the combination right servo pulse 1600 microseconds left servo pulse 1400 microseconds

after uploading program this bot moves in forward direction but speed of left servo more than right servo ,so it doesn't move straight

The exact no-motion value may not be the same on both servos. The speed of rotation when moving a fixed value away from stopped may not be the same on both servos, and may not be the same in each direction on the same servo (that is a delta of +100 and a delta of -100 may not result in the same number of rpms in each direction). Welcome to the real world.

If you need to make independent servos track precisely, you will need to add some sensors that can report the actual speed that the servo is turning, and use that feedback to adjust the values written to the servos.

thanks for ur suggestion. how can i identify maximum speed of servo with command "Microsecond" without sensors . because when i give command 'writeMicroseconds(9500) to a servo motor it is moving clockwise even though its range is 500-2500

9..5 ms out of a frame time of 20ms is silly. What are you trying to do?

i write 1500 microseconds which stops servo, when i write 1800 which moves the motor in clockwise direction . my question is how i can find microseconds for maximum speed. while experimenting i just write 9500 and servo is moving in clockwise direction

What happens with pulse lengths of, say, 1000us?


common RC-servos for hobby usage - and that's what's the Servo library is written for - work in a range from 1000µs to 2000µs with 1500µs being the middle. Some may extend that range to 500µs to 2500µs with 1500µs still being the middle. If your motor work differently, you're going to need a data-sheet for it which will describe exactly what's necessary. Speculation would be a pointless exercise.

You should get the data-sheet of your servo anyway, because if it involves some kind of electronic speed control (ESC), you might need to calibrate it. Only reading the data-sheet will tell you that, psychic divination on an internet forum won't help.