Yes, that third order spline or curve works well for simple moves but what happens if the user needs to change the motion profile on-the-fly? This is one reason we dumped the sinusoidal ramps and went to 5th order ramps. It is possible to change the destination or velocity changes on-the-fly. Sawmill applications often require changing the target trajectory on-the-fly. The have been some rotary shear application that do this to.
The RMC has user programs that are written in ST and organized into steps or state. The RMC forces you to use a state machine. In the end it is simpler debug.
Most on this forum have figured it out that math is no obstacle to me. The motion target generator is the most complicated part of a motion controller. The control theory part ( PID ) is simple by comparison yet people seem to get this backwards.
I am retired now but I still visit Delta a few times a week. I still do a MS Team video call to our guy in Edinburgh once a month just to see what is happening in the UK.
BTW, I like watch Jeff Taylor on YouTube so I keep up with the nonsense in the UK.
Why? Technically I now have a king.
Having read the documentation for the Galil, PMAC, RMC, Trio, etc., they all have the same limitation which is having to cooperate with the real-time system...time-sharing.
Our approach is 8 X 32bit parallel processors that share the same memory and I/O. No interrupts and therefore no latencies and no jitter. The trajectory generator has a CPU all to itself and running a 500Hz loop (copied that from Galil), it spends most of its time twiddling its thumbs.
State machines, absolutely (there was a time when I thought I'd invented this concept
)
In the Accel state, for example, I might be say 4 samples in and a change might occur. Simply recalculate the profile (checking for silly values) and then for the 5th sample, pick-up on the new profile. The output is stuffed into shared memory and the CPU that does nothing but run the PID's picks-up on this new command. Performance anxiety? We're immune to it.
I see that the other guys run their PLC tasks on whatever clock cycles are left-over from running the motion tasks...nope, we have another separate CPU that can respond in nanoseconds.
I was just reading about a case of a BeckHoff Twincat, 1.4GHz Windows-based IPC and 4-axes of motion, dragging the IPC to its knees...
Maybe it's something in one of those endless gobbledegook menus that they have set wrong
Yeah, I sometimes watch Jeff...he's always on it. I haven't watched a TV in over 15 years and I avoid
all mainstream propaganda so I rely on a few other sources for factual information. I do have a problem with "Dr." John Campbell though. I told him that he was wrong from the outset and today he has done a complete 180 and is clearly seeking redemption :angr:
Not
my King, BTW. He was too darned friendly with Jimmy Saville.
I identify as Conspiracy Theorist and my pronouns are: Told-You-So
Rgds,
Craig