Part of the problem is that the servo controller (Stamp, PSC, etc.) has no idea of the actual position of the servo when it's turned on. In the case of a continuous motion servo, the calibration (for the "stop motion" pulse width) may be off slightly. When the controller sends initial pulses, they may be off slightly (or significantly in the case of a standard servo) and that will cause a twitch or other motion.
The servo itself may not be designed for smooth turn on since servos were never intended for the kind of use in robotics where precise position and behavior is wanted.
If better behavior is more important, you may want to consider other kinds of motors where you can control power on conditions more precisely (like stepper motors or DC motors with position encoders).
Comments
The servo itself may not be designed for smooth turn on since servos were never intended for the kind of use in robotics where precise position and behavior is wanted.
If better behavior is more important, you may want to consider other kinds of motors where you can control power on conditions more precisely (like stepper motors or DC motors with position encoders).