h a l f b a k e r y"Not baked goods, Professor; baked bads!" -- The Tick
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A stepper motor with sine/cosine drive and positional feedback can have its dynamic characteristics adjusted to simulate the old flywheel tuning dial drive, with the added bonus that the effect of friction can be cancelled out.
You turn it by hand to change an input variable, such as the frame counter
in a video clip. It would keep spinning at the same speed until you stopped it.
I see it being used as the "shuttle control" for a digital video editing suite, to mention one example.
Coupled with voice recognition, for example:
"Video one" <spin> <grab> <twiddle> <nudge> "Mark, Cut"
"Video two" <spin back; control hits start of video take and stops> <nudge nudge> "Mark" etc . . .
I found the explanation for the Windows scrollbar behavior I complained about on January 22
https://ux.stackexc...se-is-dragged-sidew
Turns out it's intended to make scrolling cancelable. But notice that most people on the linked page find the behavior annoying, and an alternative (press Escape or RMB) is at least 50% popular. [notexactly, Apr 09 2019]
More discussion of that scrollbar behavior
https://www.red-bea...crollbar-redux.html
At the end of the email on his main page on this topic, which links to this page, he alludes to the disableability of this "feature", but I can't find out where the option is in Windows [notexactly, Apr 09 2019]
[link]
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Absolutely. I'm all for more physical inputs to computers. |
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<aside>I was recently shown a software digital signal processor that simulated all the knobs in a recording studio on screen (you did have to scroll about a bit). The user of the software was really impressed. I wasn't because it was a pain adjusting all those knobs with a mouse.<aside> |
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I think I understand what you're talking about, but I don't suppose someone would mind explaining the first paragraph a little more simply to me would they? |
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st3f: On-screen sliders are usually good. On-screen rotary things are bad at best; some implementations are so bad that who ever came up with them should be forced to sit in a room ... well... come up with something. |
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One useful twist to an on-screen slider is a control which, if the mouse button is pressed, "lock" the mouse pointer in place until the button is released but cause motions of the mouse to affect the control setting. Hard to describe, but really works well. |
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kaz: stepper motors are usually run by switching transistors connecting their windings directly to the supply voltage. This simple scheme would cause them to "step" a small angular distance each time a command was issued to it, hence the name. |
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With sine/cosine drives, the two windings of the motor are driven by sinusoidally varying currents with a 90 degree offset. This requires more electronics but can produce smooth motion. |
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Since the idea is to drive a control which also is manipulated it is necessary for it to feel smooth and free of vibration, hence the drive. |
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When you grab the spinning wheel to slow it down, its position will lag behind the driving voltage. If you speed it up the position will lead. This can be sensed by a position transducer or by sensing the motor currents. With appropriate control the wheel can be made to act as if it had zero friction, ie, to keep on turning at the same speed once it was set in motion. |
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[neelandan]: I don't think kaz was asking for a deeper explanation of the drive electronics. FWIW, I think this could be done just as well, if not better, using a dc motor and a rotary encoder. Maybe add a strain gauge to the shaft (if back-EMF sensing isn't good enough). |
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[kaz]: the idea is that the computer can control the "feel" of the knob by driving the motor, so it's completely software-determined whether it's a light, spinnable knob, a heavy knob, a knob with detents and stops, etc. |
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I have long wanted to use a VCR head wheel as a computer input knob. I think I saw
one on Instructables years ago, but maybe I had the idea even before that. But I had
not considered adding a motor to it. Software-controllable flywheeling, force
feedback, detents, etc. sounds exciting! Of course, I'm never going to actually get
around to building one. But if I do, I want to reuse the rotary transformer somehow—
maybe capacitive input on the rotor? |
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One advantage of onscreen knobs, though I generally share the above-described
dislike of them, is that you can, if they are properly programmed, drag from the
knob to a point far away on the screen, and adjust it with your cursor all the way
over there. It gives you a longer lever arm, so the same motion of the cursor
translates to a smaller angular change in the knob setting, giving greater precision. (I
usually encounter this when rotating objects in graphics programs, because I don't
usually use any software that has knobs.) |
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You could do something similar with a slider (move away perpendicularly while
dragging to get a smaller range with increased resolution around the current point),
but it could be less intuitive. Strobily does that, and has a really nice interface to
help make it intuitive, but it's the one app I've seen that does it. |
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BTW, this reminds me that when you drag a scrollbar on Windows, if your cursor goes
too far away perpendicularly from the scrollbar, it stops scrolling and jumps back to
where it was before you grabbed it! I've always found that annoying and not seen the
point. On other OSes, you can grab the scrollbar, take your cursor to the other side
of the screen, and still control the scrollbar as long as you hold down your mouse
button. |
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Having only recently moved to Windows 10 (upgraded
computer at work), I've found it is getting LESS user-friendly
and, in some cases, essentially un-useable. At the very
least, a lot of functions simply need an OFF switch. Bring
back XP! |
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