* Very few servos have a 360 rotation range... +/- 90 degree is more common (the exception being servos that have had the position feed back * *logic removed and act as variable speed continuous motors). * The mine has the range (at a glance) about 200 degrees.
*Likely you are over (under) driving the position, and the servo can not physically move to the position you are requesting -- this leaves the coils energized with the servo pushing against the internal end-stop.* Sure, I was out of range and torque was quite high. But why the range isn't specified in datasheets ... applying over/under driven position one can damage servo definitely. Safe operating conditions - the first thing that should be in the datasheet, isn't it ? *My suggestion would be that you write a short calibration program with which you adjust the pulse width from neutral, one step at a time, until the servo reaches an end point (ie; the control "horn" stopped moving while you changed the pulse width), then back up until you just detect the horn has moved off the end-stop. Record that value and repeat for the other direction. Maybe put a sticker on the servo with the values of the end-point pulse widths -- neutral position should be the average of those two values.* It is difficult to estimate with the naked eye when the servo reaches the end / start points. Another detail: I observed a kind of hysteresis when the servo approaches the end or start points. I mean that by approaching one of these points I can move forward in relatively small steps. Once the limit point is reached, to go in the opposite direction, I have to take a relatively large step. Probably one of the methods for determining the limit points is current control, i.e. when the torque continues but the servo can no longer rotate, will the current rise? *Do that for all your servos, and either use the minimum span for all, or program the limits per servo (if using Python, install Adafruit Blinka and libraries for CircuitPython -- the servo class allows override of min/max pulse width; they default to 0.5 - 2.5ms, but do state that "standard" servos are supposed to work with 1.0 - 2.0ms width)* Ok, thanks. Sincerely, Pavel. -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/df3ad4ff-51b0-475b-b9b6-4e69bcf60631o%40googlegroups.com.
