Don't want an "S" curve..need a cosine curve

Hi uncle Lamboom,

how you adjust the frequency in cosine mode?

osmanmom said:

Hi uncle Lamboom,

how you adjust the frequency in cosine mode?

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It's in the SIN equation: Sine_Time/Period, where Sine_Time is from the ModReal expression (It's an Omron Sysmac Studio thing.) This info came from an Omron Engineer, Tyler Corbett, in Canada. (where all the friendly people live..


SampleTimeSec:= TO_LREAL(TimeToNanoSec(GetMyTaskInterval())) * 1e-9; //in this case it equals 0.001 sec .. it's sensitive to whatever the task interval is in the Omron NJ

Sine_Time:= ModReal(Sine_Time + SampleTimeSec, Period

Position := Amplitude * SIN((2 * Pi * Sine_Time / Period) + (Pi * 1.5) + Amplitude

Attn DIRT: Back to that Tsunami equation.... I Changed to using State Trackers (like your Stages) .. That worked well .. No clunks, and the sequence runs fine; but, only up to a point. There is a point at short periods (0.3 sec) to the positive peak of the cosine ramp up, when the control fails and the linear motor runs away negatively into the hard stop. (have nice shock pads for that..)

This may be due to the position equation itself. By creating only 180 degrees of motion mathematically ( SIN(2 * Pi * Time increments/Period) + 270 degree Offset) The 2 is not in this equation) The equation is only for a half cycle... perhaps it should be in the equation... or something a little larger than 1 . Because, the "end" timing is too critical. In only one CPU cycle, (0.001sec) the curve will go from + peak(max) to zero!. Probably, better to make the cycle go slightly past + Peak(max), but try to catch the + Peak(max) with the IF-THEN statement.

Edit ... Just tested it .. Yup... gotta use a position equation that passes the peak a little... I now can do a "impact' simulation of a stroke of 100mm in 0.1 sec .. or faster.. LinMot is awesome!

Nice plot.

That looks good for one wave. The tracking errors are small so you did a pretty good job of tuning.

You can see it takes about 0.15 to 0.2 amps just to overcome friction. That is a lot relative to the peak.

Hi Peter .. always nice to hear from you. Ya know, after trying to get an Omron NJ to do non-typical machine automation moves, I have come to appreciate the incredible work your design team created in the Delta programming software. Sure, I was a newbie, but it was so intuitive, and simple to create everything I could imagine from curve shapes determined by complex mathematics, and ramping any variable .. all, on the fly, in real time. Damn near everything you need to do with Omron NJ is by brute force. Well, that's not entirely fair ... they do have a few bells and whistles... an' their NA HMI is cool (not as good as Red Lion .. but OK.)

These are very slow test moves. When moving water, the LinMot needs harder PID tuning .. I see forces up to 135 pounds.. with some moves in the 0.4 Hz range.. I can't use hydraulics, leaks are inevitable, an' water and oil don't do well together. You have any really cool projects lately, other than helping land the Curiosity rover on Mars? Also, did you know Delta played a role in the last King Kong movie?

RESOLVED Working... Thanks all.. Peter, Osmanmom, Dirt, Kvogel (Ken) & Highland Controls ... Life has meaning

It looks like you did it!

Also, did you know Delta played a role in the last King Kong movie?

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I didn't know that. I usually don't get too involved in tech support unless all our tech support guys are busy or the problem is difficult.

Movies are great for publicity but there are a few people that do most of hydraulic controls. They bought a RMC for movie making but they buy only one for all future projects/movies. Earlier this year I talked to the guy that did the hydraulic controls for Transformers 1,2 and 3. For some reason he didn't do 4 but is going to do 5. He bought only one controller and will use it for all his movie projects. I get more excited when a OEM standardizes on our products because that is recurring sales and usually after the first few systems they are cookie cutters so support is low.