I realize this is not strictly a code question, but I guess it belongs here anyway. If not, my apologies in advance.
Being as there's no inbuilt way to change the vibration intensity for the droid in code I'm using a kind of PWM control (switching the vibrator on and off at high frequency gives me a kind of control over vibration intensity). Right now I'm using a 20ms period (for example, with a 50% duty cycle the vibrator is on for 10ms and off for 10ms and it kind of feels like half power).
My question is, can some damage occurr to the vibrator motor using this kind of control?
I'm no engineer, but we're in luck because there is one sitting next to me. Apparently there's a kind of life cycle to things that relates in some ways to altering the state and in some other ways to duration of use so yes doing what you're talking about will stress the device in one way by trying to get something to go from 0% to 100% and back again very rapidly, but relieve some stress by only having it on half the time. Overall, what you're talking about doing shouldn't do any harm that would shorten the Android's life span as long as this pattern isn't intended to run for very long. I would definitely suggest getting in touch with someone who knows the mechanical part of the device more intimately because every device is different and general knowledge doesn't always translate into spot-on specific knowledge.