On 09/25/2016 11:52 AM, Kirk Wallace wrote: > Hmm... I found this which means I need to look a little > closer at my pin list: "... (All float output) > 'ppmc.<port>.encoder.<channel>.velocity - Velocity scaled > in user units per second. On PPMC and USC this is derived > from raw encoder counts per servo period, and hence is > affected by encoder granularity. On UPC boards with the > 8/21/09 and later firmware, velocity estimation by > timestamping encoder counts can be used to improve the > smoothness of this velocity output. This can be fed to the > PID HAL component to produce a more stable servo response. > This function has to be enabled in the HAL command line > that starts the PPMC driver, with the timestamp=0x00 > option. ..." On older PWM boards without the timestamp feature, and all USC boards, velocity is just delta scaled by the the encoder scale factor. On the newer PWM and PPMC boards with the timestamp feature, then the velocity is smoothed by estimation based on time since the last encoder count. This is considerably smoother than velocity derived from delta, which is just current position - last position, and this quite noisy.
Jon ------------------------------------------------------------------------------ _______________________________________________ Emc-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
