Does this article about cam tables make sense to anybody.

I have read it and I can understand it. It is written in a language that can be understood by non-experts in the subject (which includes me ..). Maybe that is the problem for the editor. Most papers are written by experts for experts in a language that is gibberish for non-experts. Your paper does not appear imposing enough, which I find a good thing.

There are a couple of minor thing I would moderate.
a) There should be a pre-amble at the beginning. What is the paper about and why should I read it.
b) Illustrating the text graphically; for example "jerk, notice that this a constant and changes in steps" would be good to see in a graphical curve.
c) Some statements are presented as-is and could be explained a bit more in depth. I.e.
"The intervals do not need to be equal", for it to be possible to generate a spline for the given points ?
"[..] but there is a limitation. Standard cubic splines do not make it possible for the first derivative, velocity, or second derivative, acceleration, to be both 0 at the end points. It is only possible to set one or the other but not both", it may not be important why this is so, but it would still be good with further explanation or illustration.
 
I too have read it & understood it. I also think the reason it was rejected is due to a non technical approach, I understand your reasoning & for people like me that do not have the experience or level of maths it made sense, it certainly needs expanding I'm no expert by any means & found it informative and certainly good for this site.
although probably not the same thing but in the early 90's I was tasked with developing a Scada system, it was a commercial system & it's ability to use programs written in "C", one of the engineers designing the system passed me a couple of A4 sheets of paper with a calculation on it, yes it was mind boggling, part of the project was a gigantic circular diamond tipped circular saw that cut steel pipes & box section to length on a continuous line, the idea was to measure the tube as it was formed, match it's speed & cut it & return ready for the next one, the calculation was used to obtain maximum life out of the blade within the time of the travelling cut, it basically used a calculation that took the tube sizes, round or square, wall thickness Blade Dia, number of teeth etc, and did god knows how many iterations to produce the required metal removal rate & adjust the profile as it passed through the tube. we called it the Rubik's Tube calculation, My job was to convert the calculation into "C", however, there was a problem that the version of "C" used did not have floating point maths, the libraries required were from the States (Brain boxes I think) & lead time was 8-12 weeks, too late for the project, so we had to not only take the formula & turn it into "C" language but also convert all the floats & use integer maths etc. to form the calculation, I did not have the math skills to understand the calculation & the guy who designed it had no programming experience in C, however, he did the calculation on a HP programmable calculator, this took over 25 seconds to do the calculation so quite a complex equation, I produced the code, entered known parameters & compared the results to the HP calculations it worked a treat. There was a project to re-do it when the libraries arrived, but in the end this never happened.
 
The article content makes sense, sure. My LibreOffice could not display the equations, but I am sure those are correct; did you submit the article as a PDF?

Was there any feedback with the rejection?

Caveat 1: several of the questions I ask here may be moot, depending on the context and the expertise of the typical audience.

Caveat1 2: I am not trying to be critical here, or at least I want to be constructive in any criticism! I am trying to put myself in the editor's shoes and spitball some ideas why they might have rejected the article. Please forgive any bluntness as I have not yet had breakfast. So here goes.

If I were the editor, I would be making the following observations and/or asking the following questions.

1) Where are the abstract, summary, discussion, conclusion? What exactly is the question being answered i.e. what is the point, or the problem being solved? What is the context of the problem (e.g. motion control in non-analog PLCs)? Perhaps the "So why does it matter" paragraph could be integrated into an abstract and provide the point; but where it is, near the end of the article, it does not help with that.

1.1) I.e. what does this article offer that is new or interesting, and can I find out right away or do I have to read the whole thing before I can answer that question? The latter approach is for novels; the former is for articles. The editor's task is ultimately to generate net revenue i.e. revenue in excess of the effort to publish, and that via publishing articles, so ultimately the only valid reason to accept an article for publication is that they believe the publication's target audience will have a reason to read it. "For all the Athenians and strangers which were there spent their time in nothing else, but either to tell, or to hear some new thing." Every item I write here ties back to this primary issue.

2) This article would improve with proofing.

  • AFICT it needs a spellcheck on the current version, e.g.
    • "unknows" (unknowns).
  • The grammar might work better if it were in a literary/publication style; it is currently conversational (maybe you spend too much time in fora like this;)) and often wonky or redundant e.g.
    • ... cubic splines of order three.
    • ... relatively distance intervals.
    • The blue line shows the y values being using linear interpolation as a function of the x value on the x axis.
    • The same also applies to the velocity and acceleration as well.
    • The radius of the cam does this by varying the radius as a function of angle
3) PLCs are mentioned in the first sentence but never again explicitly. What is a PLC? Why are PLCs relevant? How are splines/cams used in the context of PLCs?

4) Along that line, a fuller definition of "cam" would be helpful. Almost every reference to "cam" or "cam tables" is as a synonym for spline e.g. "... of a spline or cam table." If it's only a synonym, then it's redundant, so why is it mentioned and/or defined and/or important? It feels like the first five sentences lay out a skeleton for the abstract of the article, but the changes in context - cam shapes, cam tables, virtual cams, cams with (physical?) radii and angles - from sentence to sentence will be followed by the cognoscenti only, and the article is not for them. What is the difference and/or significance and/or context of these terms: cam; virtual cam; cam table; cam shape; etc.

4.1) Further along that line, perhaps a definition of spline might help as well; as currently written, the article assumes an understanding of splines. E.g., start with Wikipedia: "In mathematics, a spline is a special function defined piecewise by polynomials."

4.2) Hmm, you also wrote this:
In the past [what does that mean? What was different in this nebulous past, are splines really such a recent invention that ...] one would simply do a linear interpolation for position, but this will result in discontinuities in velocity and acceleration, which isn’t good if feed forwards are being used. [wait, that's a new term; what the heck are feed forwards and why are discontinuities a problem?]
5) Ah, so putting those last two together, we can now see that the problem is about interpolation and discontinuities! Oh, and by the way, there it is: the raison d'être for splines, cams, and the guts of the abstract this article. We finally found it, but never mind: it's the third paragraph from the end, so no one will ever know ;).

6) Perhaps a worked example of splines, with application to cams in a PLC would add some meat. It would be best to add something novel. There are general statements about splines, some of which could perhaps be derived from Wikipedia, but little detail other than the plot.

7) What is the magazine and/or its area of interest? What does this article contribute in that context?

Summary


From the editor's standpoint, this is perhaps interpreted as a transcribed monologue, or answer to a problem that is either unstated or hidden near the end of the article. It is essentially un-proofed, so that is on the editor's, or their team's, shoulders.

Is that what they want to spend time and resources on now as an eventual article in their magazine with an expectation of it eventually generating revenue? Again, I apologize for the bluntness of my opinion, but you asked.
 
I have submitted this tread to a magazine and it got rejected by the editor that obviously has never done motion or used cam tables.

I think it would depend on the magazine... is this something that most PLC programmers/techs would use or understand? no, and would bubba need to know it? not a chance... the only table that bubba knows is the one pushed against his belly at dinner time.

If you would not mind, I would like to use it... if I have your permission, I have a blog and I am sure that some of my customers would enjoy reading it
 
This is supposed to be for a magazine article for hydraulics and pneumatics, not a technical paper. Magazine articles typically don't have abstracts. Also, the articles should be about 1200 words.I know I could explain more, but I am not writing a book.


The I am not supposed to get into the heavy math. The idea is to let people know what to look for when they need to solve problems where a linear actuator is moving something that rotates or a non-linear function needs to be generated using a few points.


The equations are written in LaTeX. The equations will not show unless you have the MS Word App. Even the web based MS Word will not show the LaTex equations. I like using LaTeX over the MS equation editor.



The editor wants me to "fix" it by Friday but I don't think I will.


@Geniusontraining, no, not yet.


The problem I see is that I basically wrote this article for those that might be using/programming a hydraulic motion controller. Basically, that means people like are here on PLCs.net as opposed to those that are just trying to pipe oil from here to there and keep it off the ground.
Perhaps I should save that article for a magazine that PLC programmers would read, if they still read magazines.
 
Although I have little experience in motion control, a few stepper drives & a few servos, so I know perhaps more than PLC , I found the article very interesting, it reinforced what I thought I already know.
I like the fact it was kept simple, I did originally think the article was to be put forward as a paper, hence my comments. I respect very highly Peter's knowledge, not only on motion but in PLC & automation in general. his posts have been very informative & given members of this community good advice which I hope he continues.
 

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