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  1. Re: How to change the speed of the AX12a and Read its current speed ?

    The value range is documented in the manual for the servo. I don't remember the exactly values, but because it's a 2-byte register, the value range is higher than 0-255.
    The "_L" and "_H" are the...
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    Question(s) Re: torque control for ax 12a

    Yes, almost all motors of this kind have a continuous duty rating of 20-25% of the maximum instantaneous rating. It's a fact of physics.

    There is another thread on this board about adding external...
  3. Re: Mech Warfare at Bay Area Maker Faire 2019

    That's 10 minutes from where I live and 5 minutes from where I work, so ... yeah, I'll have to be there. I'll borrow my daughter's AX-12 based 'mech. (Onyx has donated too many pieces to be...
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    Re: C program for AX

    Yes, a zero bit is sent as wire-to-ground on the TTL UART bus. It works fine to wire a microcontroller UART straight to the servo, EXCEPT when the servo tries to send a response back, the...
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    Re: XL430-W250 Stop moving randomly

    Are you sure it's the motor? If so, is it signaling an error? (Not reading status back is in general a bad habit, because it makes debugging harder.)

    If you hook up a scope or logic analyzer on...
  6. Re: Dynamixel MX-64T Torque control with Arbotix

    Have you enabled torque with register 24?
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    Question(s) Re: torque control for ax 12a

    If the servo cannot get to the desired goal, it will generate an error to tell you this. The practice of "set a goal position that is not achievable" is not generally useful for controlling these...
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    Re: XL430-W250 Stop moving randomly

    Not really. The main question is if you have command response turned on; if so, you may have to wait for a timeout if the servo didn't get the packet (because sometimes it's slighlty slow to...
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    Re: Puppet Master/ Slave setup

    Is the theory that you have two robots, one to capture the pose, and one to play it back?
    That would require software.
    The user "tician" on this board used to support a graduate art program that...
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    Project Re: Sinusoidal Servo control using MATLAB

    I don't know how fast Matlab can run -- can it run at 100 Hz itself? If not, then you're going to have to live with whatever it can do ...
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    Project Re: Sinusoidal Servo control using MATLAB

    The best you can do is to send a very high speed stream of updates -- say, 100 Hz -- for where you want the position to be.

    Let the control algorithm and damping inherent in the servo then drive...
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    Re: Puppet Master/ Slave setup

    The RoboPlus software that comes with the Dynamixel series of servos can do some of those things without programming.
    You have to read the instructions, which are sometimes hard to just FIND, and...
  13. Question(s) Re: Dynamixels AX-12A on OpenCM 9.04 + OpenCM 485: how to send instruction packets

    Here's my setup code for OpenCM 9.04:


    void DxlIO::begin() { afio_remap(AFIO_REMAP_USART1);
    afio_cfg_debug_ports(AFIO_DEBUG_FULL_SWJ_NO_NJRST);
    gpio_set_mode(PORT_TXRX_DIRECTION,...
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    Question(s) Re: Dynamixel Robotis AX12A - half duplex

    1. Yes, if you set the register to 1, then there will only be an acknowledgement from the servo for a READ command.

    2. You can tie the TX and RX lines together. That will make the RX line receive...
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    Question(s) Re: Dynamixel Robotis AX12A - half duplex

    Yes, you can set the response level to make it quiet. Check the documentation for register 16 (Status Return Level)...
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    Project Re: More Mule then Rover?

    Btw, the CC/CV lead/acid cycle that works for me is:

    - Set constant voltage to 14.5 V
    - Set constant current to something less than the Ah rating of your battery, but in A (i e, <= 1C rate)
    -...
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    Project Re: More Mule then Rover?

    Looks cold. Better the robot than me :-)

    Lead-Acid are slow-charging batteries; there's really no (safe) way around that. You can charge them with a benchtop power supply set at constant-voltage...
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    Project Re: More Mule then Rover?

    Such an awesome remote drone :-)
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    Project Re: More Mule then Rover?

    I imagine the WiFi and cameras use wall warts plugged into the 110V inverter?

    I then imagine you could use a wide-input-range buck regulator (or two) to output the appropriate voltage for each of...
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    Discussion Re: controlling dynamixel mx-64at

    If you want to use multiple batteries, then you need to create custom Dynamixel hub boards.
    The board would pass the serial signal/s and the ground signal through, but would disconnect the 12V...
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    Re: RoboGames cancelled?

    I hate Maker Faire because it's so crowded and noisy, but if there's a dedicated spot for Mech Warfare, it's a very convenient drive or train ride for me, so I could totally do that. Assuming I could...
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    Question(s) Re: controlling dynamixel mx-64at

    A pretty easy way to control these servos is to use the OpenCM 9.04 board, and the Robotis library that has built-in functions for sending commands to the servos.

    A single 11.1V LiPo battery will...
  23. Re: dc motor, monster moto shield VNH2SP30 ,arduino uno and matlab

    Are you running the correct firmware on the Arduino?
    Can you make a LED blink using the Matlab code? (The LED lives on pin 13 IIRC)
    If you hook up an oscilloscope on the serial RX/TX lines on the...
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    Re: First steps for Super Mega Microbot

    That is freakin' scary!
  25. Thread: New Member

    by jwatte
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    News/Announcement Re: New Member

    That looks awesome! And also somewhat dangerous if it suddenly hits you...



    As long as you run them on different wires and different serial ports for the host controller, that shouldn't be a...
  26. Question(s) Re: Hex M2 Nut Not fitting into Dynamixel AX-18A Servo

    The AX-12 and AX-18 use the same physical size/enclosure -- the point is that you can interchange them!

    The M2 nuts should require firm but not hammering pressure to go in. It should go in with a...
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    Project Re: More Mule then Rover?

    From what I've learned from hand-pulled snow scoops, you may want to support up to 20 degrees backwards tilt to keep the scooped snow on the bucket. It's annoying when you try to lift things, but...
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    Project Re: More Mule then Rover?

    Looks quite robust! Now all you need is another foot of snow ;-)
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    Re: dynamixel issue demagnetize/magnetize?

    Most VFDs these days have hook-ups for brake resistors, which end up taking the load of overvoltage.
    Many battery-driven motor controllers have a diode path back to the battery for "regenerative...
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    Re: dynamixel issue demagnetize/magnetize?

    Are you using the Robotis SMPS ?

    Various power supplies may be poorly regulated to spikes in load, and swing the output voltage wildly; especially when movement stops and the motor dumps load back...
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    Re: dynamixel issue demagnetize/magnetize?

    They don't like being stalled for long times. Or, if you use 4S, for any perceptible time ... 3S is safer.
    Also, they don't like reverse polarity power. Just sayin' :-)

    Finally, you can shear the...
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    Re: dynamixel issue demagnetize/magnetize?

    This happened to me too. The windings in the servo overheated, and the motor now has a bit of stickyness because of it. The only fix is to send it to Robotis for motor replacement. The overall cost...
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    Project Re: More Mule then Rover?

    That looks awesome!

    You probably should do both current limiting and safety limit switches.
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    Re: PhantomX + CM9.04 but no Xbee!

    Also, if you have two separate gaits stored as snapshots, you can still interpolate between them as long as you can index by "logical time" (as in, "how far into the full cycle are you?")

    That...
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    Re: PhantomX + CM9.04 but no Xbee!

    It's code. Anything CAN be done. How much work it it? I don't use Phoenix, so I have no idea.

    In my own system, I have a number of input variables (amount of turn, amount of forward speed, amount...
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    Re: PhantomX + CM9.04 but no Xbee!

    I use iBus, but other than that, yes, it's totally possible, assuming that you can live with the controls that can generate that format.
    (I e, sometimes custom controllers, or game controller...
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    Project Re: More Mule then Rover?

    seeing where you go is important :-)
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    Re: 2018 Robogames Mech Target Plates/Transponder

    Thanks for the info!
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    Re: First steps for Super Mega Microbot

    Do you find a big difference between the "Onyx" black nylon versus Shapeways "Strong Flexible" in black? They're both nylon ...

    Also, for SMMB I might be able to make some parts in aluminum for...
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    Re: First steps for Super Mega Microbot

    That's super awesome!

    (Do you have access to internal company machining resources for making parts?)
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