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Servo Recorder — Parallax Forums

Servo Recorder

NWCCTVNWCCTV Posts: 3,629
edited 2015-02-14 08:17 in General Discussion
Has anyone seen or used one of these yet? http://www.servorecording.com/
Kind of a neat item. I might have to get one of the 5V ones to see how well it works.

Comments

  • Duane DegnDuane Degn Posts: 10,588
    edited 2015-02-13 22:20
    NWCCTV wrote: »
    Has anyone seen or used one of these yet? http://www.servorecording.com/
    Kind of a neat item. I might have to get one of the 5V ones to see how well it works.

    What do you want to do with it?

    It's actually pretty simple to record servo positions and play them back. There are lots of examples on the internet of robot arms which are controlled with knobs and then the positions are saved by pressing a button.

    I did something similar with continuous rotation servos but instead of saving the positions (or speeds in this case) of the servo when a button was pressed, it continuously saved the servo pulses at about 50Hz and wrote the information to a SD card.

    I used this technique to "record" and then "playback" the course my PropBOE-bot drove.

    Instead of controlling the path of the robot, the PropBOE could have been controlling a robot arm.
  • NWCCTVNWCCTV Posts: 3,629
    edited 2015-02-13 23:43
    Nothing really, I just thought it was kind of neat.

    Moderators, I am not sure why but there are 2 posts with the same title. Can you delete the one with no replies?
  • JonnyMacJonnyMac Posts: 9,105
    edited 2015-02-13 23:47
    As Duane states, it's not hard to record servo positions. I wrote a program for the EFX-TEK HC-8+ with a microSD card to record the data stream from a "buddy port" on a radio remote. The file could be imported into Vixen, massaged, and then played back. Easy-peasy.
  • PublisonPublison Posts: 12,366
    edited 2015-02-14 02:58
    NWCCTV wrote: »
    Nothing really, I just thought it was kind of neat.

    Moderators, I am not sure why but there are 2 posts with the same title. Can you delete the one with no replies?

    Got it Andy.
  • ercoerco Posts: 20,256
    edited 2015-02-14 07:20
    You can do better on your own, Andy. I cringe when I see videos like that servo recorder, big robot arms slamming from position to position. The copy says controllable speed/acceleration, but it is telling that it's not demonstrated.

    Here's an arm demo I did a few years ago: https://www.youtube.com/watch?v=4XfBVtKsFkI Slow, stately motion is where it's at!
  • PublisonPublison Posts: 12,366
    edited 2015-02-14 07:58
    JonnyMac also did a nice article in Nuts and Volts using the SX.

    http://www.parallax.com/downloads/nuts-and-volts-basic-stamps-volume-8

    Look for "Where's Waldo, (Column 145)
  • Duane DegnDuane Degn Posts: 10,588
    edited 2015-02-14 08:17
    erco wrote: »
    Slow, stately motion is where it's at!

    That looks much better than the other servos slamming into their positions.

    Since I've been working on my hex again, I've been noticing the movement of other hexapods. I've noticed there are plenty of hexapods which slam their servos from one position to the next. Most hexapods appear to do a good job of controlling the servos as they move from point to point.

    With the hex, my main concern is trying to keep the body moving at a constant speed but I've also experimented with accelerating servo movements. What I call pseudosinusoidal is really sinusoidal, As I should have known (I minored in physics) there is more than one way (or equation) to generate sinusoidal motion.

    @Andy, Jon may call it "easy peasy" and it kind of is, but it's only easy if you know how to do it.

    As has been mentioned, the positions may be saved to a SD card or to EEPROM or some other memory device. The input can be from a RC receiver, a RC transmitter, an IR remote, potentiometers or a long list of other input devices. If you need some help writing code to turn one of your Propeller boards into a servo recorder let us know how you want the data saved and what sort of input you want to use. We could probably point you in the right direction to get you started (or as often happens, to get you finished). :)
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