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I have built a CNC machine, so I have first-hand experience here.
It depends how the system fails.
If they fail by not scheduling for 100ms (or even 1s), there is probably no problem besides delaying the work.
If they fail by sending the wrong commands out to the equipment, things can be worse.
But these do not require real-time scheduling to operate.
Real time for what?
Posted Nov 13, 2012 22:36 UTC (Tue) by man_ls (subscriber, #15091)
Posted Nov 13, 2012 22:58 UTC (Tue) by dlang (✭ supporter ✭, #313)
These things rely far less on precise timing than you think.
Just about all of the DIY devices rely on stepper motors, which move a specific distance when pulsed, not normal motors run for a specific amount of time.
If the pulses are late, things move a little slower. If there is enough momentum in the system, it's possible for that momentum to cause the equivalent of 'jumping a tooth on a gear' and being slightly out of position, the solution to this problem is to slow the machine down a bit.
synchronization between different pieces is a matter of either moving one motor, then a different motor, then the first one again, or in setting up the movement for both motors and sending a 'move now' pulse. In either case, slight delays don't break anything.
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