Society of Robots - Robot Forum

General Misc => Misc => Topic started by: airman00 on November 16, 2007, 02:27:30 PM

Title: Operating Angle Pulse???
Post by: airman00 on November 16, 2007, 02:27:30 PM
On the servo city website it lists this as one of the specs for the HS-311

" Operating Angle: 45 Deg. one side pulse traveling 400usec "

What does that mean?
Title: Re: Operating Angle Pulse???
Post by: Fredrik Andersson on November 16, 2007, 03:50:27 PM
It can't get better explained than in this link (http://servocity.com/html/hs-311_standard.html).

The total range is of 90 degrees, 45 on both sides that is.
Title: Re: Operating Angle Pulse???
Post by: Admin on November 16, 2007, 03:53:47 PM
Good question.

The exact same question has been asked before (http://www.societyofrobots.com/robotforum/index.php?topic=34.msg233#msg233) . . . but my previous guess was definitely wrong . . .

So let me upgrade my guess . . .
Sending a command between 1500 to 1900usec rotates the servo from 90 degrees to 180 degrees. And 1900-1500=400usec, with 90 degree travel. Neutral position being 1500usec.

Now servocity.com thinks that servos can only rotate a total of 90 degrees, for 45 travel. For example, this pic for 180 degree servos on their site is obviously wrong causing constant confusion on this forum:
(http://www.servocity.com/assets/images/90_Servo_Angle_Schematic.jpg)

So when they wrote "45 Deg. one side pulse traveling 400usec", I think they meant to say "90 Deg. one side pulse traveling 400usec from neutral".

Or in easy to understand terms, send it 1900usec to rotate to 180 degrees, 1500 for 90 degrees, and 1100 for 0 degrees.
Title: Re: Operating Angle Pulse???
Post by: Fredrik Andersson on November 16, 2007, 04:00:29 PM
Thanks Admin, i guess i was confused as well ^^
Title: Re: Operating Angle Pulse???
Post by: HDL_CinC_Dragon on November 16, 2007, 11:40:15 PM
so 1100usec will set it to neutral position?
Title: Re: Operating Angle Pulse???
Post by: Admin on November 17, 2007, 08:44:27 AM
"Neutral position being 1500usec." :P

In my experience tho, its +/- 50usec off sometimes, even for the same type of servo. I guess its manufacturing errors . . .
Title: Re: Operating Angle Pulse???
Post by: Ro-Bot-X on November 17, 2007, 11:02:56 AM
You may want to know that there are servos that rotate 180 degrees and servos that rotate only 90 degrees! The 90 degrees servos are used in aeromodels. Here is a sample:

Quote
CS-10, CS-20, CS-600, FP-S148
These servos use an indirect drive potentiometer for feedback to determine positions. These servos are designed to rotate approximately 45 degrees in either directions from center for a total of nearly 90 degrees. The servo is designed to be used with model airplanes and cars, but when used with the SV203 or SV203B/C, it can be made to perform other tasks such as mini-robotics, animatronics, and computer motion control.
Title: Re: Operating Angle Pulse???
Post by: Admin on November 17, 2007, 04:26:51 PM
I've even seen one that does 360 deg (not continuous/modified) . . .