Clarification of Terminology

Lynxmotion Legged Robots
1

Jim and/or James (I would never call you Jim),

If knowlege is power and little knowlege is dangerous, then beware because I am powerfully dangerous.

For nearly two weeks I was totally baffled by a comment in your bratosf3.bas program which stated that buttons A and C increased and decreased the offset by 5us. “us” didn’t mean anything to me. From electronics, I knew that we often use our letter “u” in place of the Greek letter “mu” to mean “micro” as in “uF” to mean microfarad or one millionth of a farad. From geometry and astronomy I recalled that circles and arcs are divided into degrees, minutes, and seconds.
Therefore, 5us must mean 5 millionths of a 360th of a degree of arc.

But this couldn’t be right! Even Hitec’s wonderful servos wouldn’t be capable of resolving such an infinitesimal amount of rotation. Nor would I be able to see it while setting my servo offsets.

My Aha moment came while reading Jim’s 19 Dec 07 answer to joey2’s forum question “Where to find servo specifications?” “5us” did indeed mean 5 micro seconds NOT as a measure of rotational movement BUT as a measure of time duration of a signal pulse width. Suddenly it all makes sense.

Please tell me I’m finally right. And please remember when you’re commenting code that for all the geniuses crowding your Forum, there are still some dummies like me reading it also. We grew up with slide rules before home computers, calculators, microcircuits, or even transistors existed. But we’re still trying to learn, and Lynxmotion provides a great way to do it.

Thanks, Ted

2

Hi Ted,

You are correct. the ms is talking about microseconds (time duration) and not a measure of rotational movement.

Kurt

P.S. - I also remember the days when they taught you how to use a slide rule :laughing: :blush:

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Whats a slide rule? lol jk - I know what it is but it was way before my time.

4

Hi Ted,

Sorry it wasn’t clear to you. It’s difficult to know what concept will be missed by a new comer. In fact there is no perfect “standard” for hobby servo positioning. We have become familiar with what to expect, but there are several pulse / position relationships within the Hitec family. Suffice it to say. The pulses directly effect the position of the output of the servo. A pulse / degree relationship can be established and utilized to make reasonably accurate movements. The pulse / degree relationship is relatively standardized within a specific family such as analog, digital, robotic, hi-res, etc.

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Thanks to Kurt, Mike, and Jim for your replies. I don’t feel so alone in this wilderness anymore. :smiley:

Actually, thanks to all the wonderful contributors to this forum. It is a great resource which I revisit over and over again. The wealth of technical information is extremely helpful, and some of the design proposals are awe inspiring.

Ted