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maximum values of servo-movement

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Rookie ( offline )
Posts: 12
Posted: 2006-10-18 12:38 
Hello mates!
I've got my new L5 Arm and SSC-32 today.
While I'm still building the parts together, I played a bit with the servos and the LynxTerm-Software.
I asked myself about the limits of the servos to move.
So I tried the HS-81 and one of the HS-422 servos.
The HS-81 could only move to the default of 750 and 2250. When I tried to extend the values, the HS-81 made some noise, so I stopped trying this.
The HS-422 moved from 500 to 2495 without any problems. Above 2495 it made the same noise as the small one.

:arrow: And now my question: Has anybody checked the limit for these servos to move, or is it just a funny game to find these values individually for every single servo?

It´s just, when controlling the arm with my own software, I may have to set some individual limits?!

Ahm, hey: Is it usual that each servo has its own 1500 position?
I think they are extremely different!

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Last edited by T-800 on 2006-10-18 12:54, edited 1 time in total.

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Guru ( offline )
Posts: 2956
Posted: 2006-10-18 12:53 
T-800 wrote:
:arrow: And now my question: Has anybody checked the limit for these servos to move, or is it just a funny game to find these values individually for every single servo?


Most servos are capable of moving within a 180 degree range, but some digital servos must be programmed to increase the standard range they move. This may vary a bit from servo to servo, even within the same manufacturer's product and same servo model.

T-800 wrote:
It´s just, when controlling the arm with my own software, I may have to set some individual limits?!

Ahm, hey: Is it usual that each servo has its own 1500 position? I think they are extremely different!


Every analog servo has to be individually centered if you expect to get any sort of consistent results from it. This can be done with an adjustment to some servos or in software by finding an offset to the position settings when you send a command to move a servo.

I have used the software approach with my first robot, which works well for me. I have an offset value for each servo that I apply to every position change for that particular servo. This way, I can still use the actual move values, but the offset adjusts for the individual servo characteristics.

8-Dale

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Guru ( offline )
Posts: 9257
Posted: 2006-10-18 13:01 
T-800 wrote:
And now my question: Has anybody checked the limit for these servos to move, or is it just a funny game to find these values individually for every single servo?

It´s just, when controlling the arm with my own software, I may have to set some individual limits?!

Ahm, hey: Is it usual that each servo has its own 1500 position?
I think they are extremely different!


Hitec Servo Basics 101
Each servo is different. However each servos center position will be at least within 15° of each other. Always test the servo carefully to determin it's full range. This can be done with the Lynxterm program, by slowly adjusting the position slider until the servo has reached the +/- 90° position from centered, or untill it stops moving. This is the farthest you want to move the servo. All Standard size servos can do a full 180° range, but micro servos may not be able to do the full amount. I have not seen any standard size servo damage itself from being commanded past it's mechanical limit, but micro servos may be.

The SSC-32 has a powerful feature to "fix" the fact that each servo has it's own 1500uS position. It's called the PO (pulse offset) command. This allows you to send the SSC-32 a + or - 100uS offset, so after this command is received sending that servo channel 1500uS will position it exactly to center.

All of our PC software for controlling servos allow the center, left (min) and right (max) values to be set as angles, then the programs can manipulate the servos with angles instead of discrete values. This makes it much easier to make sense of these funny little servos. :D

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Guru ( offline )
Posts: 2956
Posted: 2006-10-18 13:16 
Robot Dude wrote:
All of our PC software for controlling servos allow the center, left (min) and right (max) values to be set as angles, then the programs can manipulate the servos with angles instead of discrete values. This makes it much easier to make sense of these funny little servos. :D


You are exactly the kind of person I enjoy doing business with, Jim. :D I believe we think very much alike in how we do things, but admittedly my implementation of such is not as good as yours sometimes. I am learning though, even at my age. :D

8-Dale

_________________
I can usually handle complexity. It's the [b][i]simple[/i][/b] things that always confound me..
Check out my [url=http://www.hybotics.me]blog[/url] now!
Open your mind, Read, Learn, Think, Apply..


Rookie ( offline )
Posts: 12
Posted: 2006-10-19 12:18 
Thanks guys!
This is what I wanted to hear!

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