overdrivr:
What you should do is power the servo with an external source, the arduino should just send the commands. In practice, plug the servo power pin and ground to a power source, and the servo command pin and ground to the arduino.
this is also another way that i am thinking of. But i need another power source..the external power source u mean is battery?because i wish to make a easier carry and mobility sensor...hope my sensor will not be too much stuff on top. Is that mean i need to use another 1 arduino board?
Any more suggestion is appreciate...really need help here.... =(