PCW wrote: Note that as long as you can reliably meet the 1 ms servo thread deadline
with a few 100 usec to spare, there is no advantage to futzing around to get
the minimum latency as it simply does not matter (at least with most hardware interfaces)
That looks very good, but only one glxgears and 10 minutes time.
Leave it for an hour at least 10 glxgears, play youtube videos, copy some files around.....
i retweak the kernel,, and running the test again with 10glxgear
the servo i m using is delta A3 and it have 3.1khz bandwidth,,, is this should match the servo thread or its not related
No, assuming either position or velocity control in the drive, the servo thread
only need be fast enough to allow velocity ramp up and down with enough
steps to be smooth (this is acceleration dependent)
It depends on the system acceleration and accuracy requirements.
1 KHz is usually fine. You can calculate the chord error
(caused by linear interpolation between sample period waypoints)
and see if its significant with your machine motions constraints:
Chord error polygon vs circle = R (1-cos(180/N))
R = radius
N = sides
R = Minimum Radius= V^2/A
N = Sides = T_Circle/T_Sample
That should be fine for a 1 KHz servo thread. You can also get some idea of the network
stack latency by pinging the Ethernet card and checking the min and max ping times.
The first ping will likely be longer since the host needs to acquire the remote cards
MAC address via an ARP transaction.
