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Author Topic: question about a dual rotary servo configuration  (Read 553 times)

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Offline jeremyreganTopic starter

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question about a dual rotary servo configuration
« on: February 24, 2013, 09:47:03 AM »
Hello all!  Thank you for the opportunity to use your forum.

My question is in regards to creating a dual rotary servo configuration.  Imagine a kitchen-aid mixer's dual action motor, but with servos.  I think the main problem is the wires twisting on the inner servo.  Can you tell me how I would solve that potential issue?  Do I just need to have gears that turn other gears only?  Sorry this is open-ended.  I am looking at this motor:

http://www.pololu.com/catalog/product/2274

I also have some general questions regarding servos but I am trying to do searches for that.  It seems like they come with a bundle of wires to interact with it, that control different things.  I found some of the following info:

Quote
- 4 -
(pole position angle
of encoder)
Enter 5 for Hall startup, US single-ended signal, P106 Hall offset
Enter 6 for Hall startup, EU diffe
rential signal, P106 Hall offset
0 and 2 are sin/cos encoder modes pending drive firmware version.
3 and 4 are resolver modes for future availability.
106
Correction angle of
encoder (Hall/pole
position offset)
Not used for encoder only commutation (no comm tracks). Reserved
for FUTURE Hall/Encoder and Resolver commutation mode.
111
Ls inductance, L-N
Enter the inductance in Henries.
For L-L motor spec, L-N = 0.5 L-L.
112
Rs resistance, L-N
Enter the resistance in Ohms. For L-L motor spec, L-N = 0.5 L-L.
*** end Motor Settings window ***
109
Pole angle finding
start signal
Enter 0 for test motion activation on first enable signal.
Enter 1 for test motion activation on power up.
Refer to current manual or connected drive version choices for other
available activation modes.
120
Motor thermal
protection
To activate, enter 2 for servo motors
. This is I2T type protection. In
general, multiple (redundant) forms of thermal protection are
recommended. Note that PTC ther
mistor signals are NOT directly
compatible with the iDrive actively sourced digital inputs. An external
PTC analog signal/switch output convertor would be required.
Another possibility is that all digital inputs are needed for other more
critical application functions.
121
Motor thermal
category
Enter 0 for maximum I2T protection curve (shortest trigger time).
P121 can be increased as long as the actual motor temperature is not
exceeded e.g. to eliminate nuiscance tripping cases.
EXAMPLE MOTOR PARAMETER SET:
Motor file for BM060-1C1 with BDx071 drive (10Arms peak 10s current, 115Vac/160Vdc).
Motor specs:
Rated for six step operation.
160 VDC winding
2000 line/rev TTL encoder, no external signal convertor
Max speed = 5400 rpm
Continuous current = 2 amps, 0.82 x 2 amps = 1.65Arms
Peak current = 6 amps
R line-line = 12 ohms
L line-line = 12 mH
Pole count = 6
Par # Value Parameter Description
3 300 Maximum torque current in percent of rated
5 4500 Maximum speed (encoder freq limited)
8 4950 Over-speed error (set 10% higher than Max speed)
70 2000 Encoder increments
71 1 Encoder type
100 270 Rated frequency of motor
101 5400 Rated speed of motor (max no-load speed)
102 160 Rated voltage of motor
103 1.65 Rated current of motor
105 1 Motor type
107 1 Pole Finding Method = encoder commutation
109 0 Start encoder commutation on initial enable


Let me know what you think, am I on the right track?  I was planning to control the servos via a  PLA that I will have preconfigured output configurations to match the servo configurations, then have the outputs of the PLA correspond to different configurations of output voltage/current wires.

Thanks!
Jeremy

Offline jeremyreganTopic starter

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Re: question about a dual rotary servo configuration
« Reply #1 on: February 24, 2013, 03:45:05 PM »
I think I have come up with something...  I can use two servos and have one attached to a gear arm that the inner gear is big and the outer gear is small, then I can attach the implement to the outer edge of the gear for its rotation.  This arm is attached to the lower servo's arm so that that arm can also control the rotational torque of the arm on the outer level.


Offline Gertlex

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Re: question about a dual rotary servo configuration
« Reply #2 on: February 25, 2013, 11:22:59 AM »
I'm pretty sure you want a gear mechanism for this.

Probably something from here will be what you need:
http://www.mekanizmalar.com/menu_gear.html
I

Offline jeremyreganTopic starter

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Re: question about a dual rotary servo configuration
« Reply #3 on: February 25, 2013, 05:27:10 PM »
Very cool site, thanks!  I am starting to have some ideas now and I've read more about the servos... so is this CPR encoder a "normal" kind of interface to an arduino?  Also, is the motor I have above "overkill"?  :)  I do want fine-grained control which from what I read it has.
« Last Edit: February 25, 2013, 05:30:25 PM by jeremyregan »

 


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