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    Question(s) Re: USB2AX seems broken

    Note that, if you're using the AX-12a pinout description in the manual, it is super confusing. The description of which pin is which is ordered "wrong" compared to the ports you see; you have to...
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    Question(s) Re: USB2AX seems broken

    The USB2AX is fine with a voltage on the VBUS line.
  3. Thread: XM540

    by jwatte
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    Re: XM540

    Really, why give HF any money at all? I like it!
  4. Thread: XM540

    by jwatte
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    Re: XM540

    Is Money Pit locked out of reach at TechShop, or just the tools to upgrade it?

    "Just" the tools. And the lifetime membership I had ... (ouch!)
    I wish I had enough garage space to put at least a...
  5. Thread: XM540

    by jwatte
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    Re: XM540

    Also, if anyone has actually built anything with the XL430, that'd be interesting, too.
    If TechShop hadn't closed, I could have upgraded the Money Pit rover to use those for steering ...
  6. Thread: XM540

    by jwatte
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    XM540

    So, who has put the XM-540 through its paces yet?
    http://www.robotis.us/dynamixel-xm540-w150-r/
    Seems like a slight upgrade over the MX-64, but also a noticeable price hike!
    Also, for legs and...
  7. Thread: ESP32 Support ?

    by jwatte
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    Re: ESP32 Support ?

    Most of the libraries for the Dynamixels are split in two parts; one is for "talking to the serial port to make it do the RS-485 single duplex thing," and one is for "formatting Dynamixel-format byte...
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    Question(s) Re: Overload error of Dynamixel XH430-V350

    The threshold is the maximum PWM value. I e, "overload" means "servo tried to drive at max PWM for too long and didn't get where it was going."

    If you apply "almost max PWM" but are holding at...
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    Question(s) Re: Overload error of Dynamixel XH430-V350

    PWM limit is how much PWM the servo will apply at most.
    Meanwhile, "overload" means "the servo applied a large enough value for long enough that we think the servo is stalled."
    The reason the servo...
  10. Question(s) Re: PIN(s) to do an interruption in an arbotix-arduino

    In the first snippet you're turning Torque on, not off.
    In the second snippet, you're turning down only the low byte of the two-byte value. Try setting register TORQUE_LIMIT_H to 0 instead to get a...
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    Question(s) Re: Wheelchair motor help

    The Invacare company doesn't have a service manual or data sheet you can call them and get?
    Yeah, most wheelchair like those are often 24V. And if you already removed the brakes, you should be able...
  12. Question(s) Re: Suggested charge settings for LIPO batteries that Trossen sells.

    For a battery I have recently used and are just re-charging, I'll use 2C unless there's a really good reason to believe the battery can't take it. (And, with 3 Ah and above batteries, my charger can...
  13. Re: So what intro to Robotics kits are people recommending this year?

    There's also VESC and ODrive! I may go with the Vesc-X for now.

    And, yes, I considered building my own, but I'd rather throw money at the problem at this point; time is my scarce resource. Plus my...
  14. Re: So what intro to Robotics kits are people recommending this year?

    December 2, I ordered a MBL1660A brushless motor controller from Roboteq, as my christmas present to myself. It was listed as "in stock" on their website.
    December 4, they mail me and say "it'll...
  15. Question(s) Re: Student Help - Opinions on highly anthropomorphised (humanlike) robots

    It seems I've managed to stay away. Probably not going to start now ;-)
  16. Question(s) Re: Student Help - Opinions on highly anthropomorphised (humanlike) robots

    That's pretty observant! I like it.
  17. Question(s) Re: Student Help - Opinions on highly anthropomorphised (humanlike) robots

    The question of whether robots will be used for entertainment comes down to whether people will want to go out into the real world, or stay inside and just watch screens. In the real world,...
  18. Question(s) Re: PIN(s) to do an interruption in an arbotix-arduino

    You don't need the interrupt capture pins; any pin can work with a PinChangeInterrupt.

    Also, this code looks weird:

    interrupt_state = (PINB & 0x1E) >> 1;

    interrupt-state will have some value...
  19. Re: Open CM9.04 - How to connect to AX (or MX) servos?

    If you're making your own board, you should make a board for a Teensy 3.2, not an OpenCM, in my opinion.
    (Well, that's what I've been doing :-)
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    Interesting Re: Lewansoul LX-16A bus servo

    That depends on how you look at it I guess. This is why voltage/current ends up being an imaginary-plane thing, and not just plain real numbers.
    To my thinking, PWM controls current, not voltage....
  21. Question(s) Re: Student Help - Opinions on highly anthropomorphised (humanlike) robots

    All three of those look creepy. I think synthetic humans will be useful for entertainment, media, and porn.
    Also, psy ops. Imagine the Russians releasing fake video of various political figures...
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    Interesting Re: Lewansoul LX-16A bus servo

    Yes, of course it does! But motors are not passive resistors. As the DC motor spins faster, the electromagnetic forces in the motor generates a back-EMF that counteracts the voltage applied on the...
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    Interesting Re: Lewansoul LX-16A bus servo

    Motors don't follow Ohm's law until they are stalled.
    If they are rated at 6V, and you run them at 8.4V, then yes, you may be getting twice the current at idle.
    However, at 6V, when stalled, the...
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    Re: Taking a journey with python3

    You are providing strings to the write() function, so yes, it's writing strings.
    However, you have expressed the string constants wrong -- Python uses \x, not 0x, for escape characters.
    Instead, do...
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    Interesting Re: Lewansoul LX-16A bus servo

    The motors don't burn out based on voltage, they burn out based on current. It's the current that causes heat in brushes and windings.
    Higher voltage makes it easier to run at higher currents, and...
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    Discussion Re: All about multi-legs robots gaits

    Yes, I use a control change lerping period. I think it's pretty fast, like 100 or 200 milliseconds, but it's still enough to make movement much smoother.
    Also, I keep a "current phase" variable that...
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    Interesting Re: Lewansoul LX-16A bus servo

    If they burned out after 20 minutes of no-load work, they are junk.
  28. Question(s) Re: Dynamixel AX-12A won't actuate if the chain is longer than 6

    FWIW, the Teensy has built-in support for half duplex driver chips; you can tell it to set a particular pin high or low based on whether the UART is transmitting or receiving.
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    Interesting Re: Lewansoul LX-16A bus servo

    A 8.4V LiPo will reasonably quickly drop down to 7.4V under load. My guess is that there's some chance that the brushes would burn out even at 7.4V; it's more likely the motors aren't dimensioned for...
  30. Re: Simulate error model in virtual environment

    Unity just lets you render things in 3D; you have to implement all of the errors and localizations yourself.
    Gazebo would probably have slightly more support for what you want to do, but you'd still...
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    Discussion Re: All about multi-legs robots gaits

    My gait engine drives the "desired end position" of each extremity over time, measured in the coordinate frame of the chassis.

    To start/stop, I use a small amount of time (0.3 seconds or so) where...
  32. Thread: Beginner build

    by jwatte
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    Re: Beginner build

    For the plates, the drawings are available in the RTeam git repository if I remember correctly.
    You should check in the "rules for 2018" proposal thread, they might have links there.
  33. Question(s) Re: Dynamixel AX-12A won't actuate if the chain is longer than 6

    If you're not building your own, yes, that's the one I'd recommend!
  34. Thread: Beginner build

    by jwatte
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    Re: Beginner build

    Xbee series 1 is what most of us use.

    I think you'll have a hard time getting enough space on the Kame for all the necessary equipment.

    The Turnigy servo is probably good enough? Maybe?...
  35. Question(s) Re: Dynamixel AX-12A won't actuate if the chain is longer than 6

    The AWG22 wires in the Dynamixel series cannot carry an infinite amount of current. Strands longer than 4 servos are not recommended.
    Instead, get a high-quality hub (I make my own; and the Trossen...
  36. Re: Open CM9.04 - How to connect to AX (or MX) servos?

    I typically get version A, and I have a bunch of the right AX/MX-style connectors in the parts bin.
    I think I got 100 of them from Digi-Key at some point. I'm almost out by now!
    I also have male...
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    Question(s) Re: Debugging phoenix code

    Yes, Arbotix has two UARTs, one of which goes to the Dynamixel bus, and one of which goes to the Xbee socket.

    You can hook up only the "Rx" part of a USB serial adapter to the "Tx" pin that goes...
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    Re: AX-12 with Python

    Glad you got it all working!
    It really is frustrating when I can't tell which bits may be broken.
    Is it my code? Is it my power source? Is it my adapter? Is it my wire? Is it my servo?
    My life...
  39. Re: Open CM9.04 - How to connect to AX (or MX) servos?

    I use a hub, and a cable that I cut off one connector, and stripped the ground and power wires. Alligator clips complete this highly robust solution :-)
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    Re: YATB - Yet Another Teensy Board :D

    I've gone both ways on current limiting resistors. A 47 or 70 Ohm resistor on a UART bus running a 1 Mbps will not significantly degrade the signal, but will add a modicum of protection against brief...
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