[NSRCA-discussion] SD-10

Mon Aug 24 20:33:09 AKDT 2009

So assume travel is 135 degrees...

The difference between 1024 and 2048 is equal to .0659 degrees... (~ 1/15 of
a degree)

1) At what servo arm length does this rotation sample become significant?

2) How much throw of the stick can our thumbs/fingers really sense?

I agree with Mark that there are too many variables in the set up to
reliably say that we can detect the difference between the two in speed or
finite stick movement (resolution).

I would agree that resolution has no influence on speed. In addition, the
speed of a control surface is relative to the many variables of set up.

If servo "A" is set for max throw at 90 degrees;
and, servo "B" is set for max throw at 135 degrees;
and, both servos are the same speed, brand, etc...

Servo "A" would feel faster than servo "B" due to less distance traveled. 

My conclusion is that even if a 40% plane did have a measurable difference
in resolution steps for control surface movement, I don't think our human
ability in stick movement is precise enough to take advantage. Also, the
speed is very subjective with too many variables in set up to compare one to
the other.

Interesting thread...

Larry

-----Original Message-----
From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Atwood, Mark
Sent: Monday, August 24, 2009 10:15 PM
To: General pattern discussion
Subject: Re: [NSRCA-discussion] SD-10

The resolution is for the full throw of the servo. If you bump your
endpoints up to 150% and have 135deg of travel, you have 512 / 1024 or 2048
individual points in between.  At a normal 100% that's across 90degs of
throw.  If you dial your endpoints down, it's spread across a smaller arc.

We're talking about extremely fine movement even at 512 resolution.  

What's nice is that all the components of the Accuracy "system" are
improving together.  The pots in the new radios (all brands) are
significantly more accurate, the digital servos of all brands are
significantly more accurate, and our linkage systems continue to improve as
well.  My argument was simply that after 1024 (and probably lower actually),
the resolution is probably not the "weak link" in the accuracy chain.  We
have too much slop elsewhere.  Even a tight servo has some lash, as do the
connections to the servo and even movement of the control surface on the
hingeline.  

Admittedly though, On a LARGE control surface like a 40% IMAC Rudder, you
can still see the surface "Step" if you move it slowly and watch carefully
even with 1024.  So to say that 2048 is not smoother would be foolish.  But
on our pattern planes and the throws we use, the other sources of error take
resolution off the critical path to more accuracy.

So to slightly change the topic, how do we get spec's on the
resolution/accuracy of the servos?  Does anyone publish that? (I'm pretty
sure Atx doesn't).  That would be as important than just about any other
spec I would think.

-----Original Message-----
From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Lisa n Larry
Sent: Monday, August 24, 2009 10:31 PM
To: 'General pattern discussion'
Subject: Re: [NSRCA-discussion] SD-10

I'm curious...

How many degree of servo throw for 1024/2048 are we talking?

-----Original Message-----
From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Ronald Van
Putte
Sent: Monday, August 24, 2009 8:34 PM
To: General pattern discussion
Subject: Re: [NSRCA-discussion] SD-10

Geez!  I was happy with 512.

Ron VP

On Aug 24, 2009, at 3:13 PM, mike mueller wrote:

>  So a 2048 is smoother than a 1024 by double. I wonder at what  
> point you no longet "feel the difference".?
>  For me it could be as soon as tomorrow. M2
>
> --- On Mon, 8/24/09, Jay Marshall <lightfoot at sc.rr.com> wrote:
>
>> From: Jay Marshall <lightfoot at sc.rr.com>
>> Subject: Re: [NSRCA-discussion] SD-10
>> To: "'General pattern discussion'" <nsrca-discussion at lists.nsrca.org>
>> Date: Monday, August 24, 2009, 3:05 PM
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> Frank, you
>> are getting your terms mixed
>> up. The 1024 & 2048 refer to the number of
>> "steps" from one end
>> of the stick movement to the other. The speed, known as
>> latency, is the time it
>> takes from the instant you change the stick to the time the
>> servo moves. Actually,
>> it is the time until the servo receives the command to
>> move. The two functions
>> are not dependant upon each other.
>>
>>
>>
>> As far as
>> keeping up, that depends on
>> servo speed. It is possible to have a switch change which
>> instantly commands a
>> function from low to high, for example. The time to get
>> there, however, will
>> depend on how fast the servo can move.
>>
>>
>>
>>
>>
>> Jay Marshall
>>
>>
>>
>> -----Original
>> Message-----
>>
>> From:
>> nsrca-discussion-bounces at lists.nsrca.org
>> [mailto:nsrca-discussion-bounces at lists.nsrca.org]
>> On Behalf Of
>> frank
>>
>> Sent: Monday,
>> August 24,
>> 2009
>> 3:30
>> PM
>>
>> To:
>> 'General pattern
>>  discussion'
>>
>> Subject:
>> [NSRCA-discussion] SD-10
>>
>>
>>
>> Hi Anthony,
>> Jim, Mark , and Others
>> who Responded,
>>
>>
>>
>> Thanks for
>> your valuable input.
>> I've read that this radio's resolution is or is
>> among the very
>>  fastest; so much so that even digital servos
>> can't keep up with it.
>> I understand  that the system is 1024 , but
>> can't help but
>>  wonder why it isn't 2048. I'm sure
>> I'll get past my
>>  hangup, but would appreciate everyone's
>> insight's on that
>> one.
>>
>>
>>
>> Thanks,
>>
>> Frank
>> Imbriaco
>>
>>
>>
>>
>>
>>
>>
>> -----Inline Attachment Follows-----
>>
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>
>
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