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    Re: Python dynamixelSDK very slow read

    It's quite likely that the problem is some combination of the Python serial implementation, and the U2D2 device. Request/response turn-around time will just take a while, as far as I can tell.
    I...
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    Project Re: Mike's SCARA Robot

    Yeah, logic is fun!

    FWIW, the Teensy 4.0 and 4.1 microcontrollers run at 600 MHz these days, and do DMA for you if coddled just right, and their development environment plugs into the Arduino IDE...
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    Project Re: Mike's SCARA Robot

    This is at the same time totally awesome, and insanely scary :-)

    Modern microcontrollers, with interrupt triggered pins and flexible I/O, are almost always able to "take a thing in" on one side,...
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    Some people get paid to build biped robots!

    Honestly, the gait they show during development doesn't look like anything special, but once they get the more fully featured bot with all the make-up on, it looks pretty good!
    ...
  5. Thread: Keras on ROS

    by jwatte
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    Re: Keras on ROS

    How do you run the network normally?
    You should be able to just run it the same way you run it for testing.
    Then build a simple bridge that publishes the output of the network as a topic.
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    Project Re: More Mule then Rover?

    Sounds like a good deal!
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    Project Re: More Mule then Rover?

    That looks like a monster :-)
    What poor lawn tractor had to donate its heart like that?
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    Re: Does anyone have a used one for sale?

    And on that note: https://forum.mechwarfare.org/ !
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    Question(s) Re: Creeper needs attack mode

    You don't need SLAM, because you can already build a map ahead of time.

    You might want to use something like a couple of ultrasonic sensors to measure distances to edges, and perhaps a...
  10. Re: Planning to build HR-OS1 robot using AX-12A & AX-18A (looking for frames)

    It may be that the best way to fix that is to learn the language and fix the errors/warnings. They're generally not particularly hard to fix, once you're into it. You could even provide a patch for...
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    Re: The task (lawn mower topic)

    That's actually pretty crazy. When a car battery is low, the alternator will have to produce a fair amount of current for a fair amount of time; I wonder if you can kill the alternator in your car by...
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    News/Announcement Re: The Robotis TurtleBot3

    The best way to learn ROS is to start picking apart modules and see how they work, then start writing your own modules (perhaps just something dumb that talks to an Arduino on a serial port to flash...
  13. Re: How to find kinematics of a system with 2 differential drives attached together?

    Why do you think you only have two unknowns? Two drive wheels per robot, times two robots, equals four unknowns.

    This is assuming the robots are attached with an articulating joint. If the joint...
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    Question(s) Re: Dynamixel U2D2 with SBC?

    The device is a USB serial port converter plus some electronics. It should work just fine with anything that has a USB serial class driver, especially if it runs Linux. The Pi should be fine....
  15. Re: Should we move Mech Warfare discussions to some other forum?

    The Discourse forum has been somewhat active, although the national shutdown has kind-of put a damper on any activity ...

    https://forum.mechwarfare.org/
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    Re: Where to find used MX servo for learning PID

    I don't know where to find them used, but the DYNAMIXEL XL430-W250-T is only $50. You'll also need some way to speak RS-485 with it -- a U2D2 or some wiring with an Arduino and a transciever or...
  17. Re: Inverse Kinematics of a Open-loop chain (SCARA robot arm)

    The question is how many degrees of freedom each joint has, and how many degrees of freedom you want to solve for the end effector.
    If you have only three degrees of freedom total, and only need...
  18. Question(s) Re: Serial Monitor keeps printing reversed question marks when using the DynamixelShield with UNO

    Also, don't remove a question just because it's answered. Others on the internet have the same question. If it's not preserved in the thread, google won't find it the next time around, and the cycle...
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    Re: RC100 data packets

    ~ is the C/C++ bitwise-not operator. Yes, this is "1's complement"
  20. Re: Connect servo dynamicel XL-320 to wizard 2.0 without U2D2

    What is the actual challenge here? You can't just use a 74241, you need a USB UART adapter, which shows up as a COM port in Windows. Then you point the Robotis software at that COM port. Then you...
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    Question(s) Re: Baudrate for dynamixels

    I just set return delay time to 0 or 1, no matter what the baud rate. I do add some parameter variation based on the specific joints; it's an interactive tuning exercise.
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    Question(s) Re: Baudrate for dynamixels

    Some microcontrollers need some time to turn around the RS-485 bus after sending the commands, so the return delay parameter makes sure the microcontroller has time to turn off the transciever and...
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    Project Re: Tachikoma by TheMaverick

    That sounds fantastic!



    Have you done the torque calculations? Will 9g servos be able to hold this design without overheating?
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    Question(s) Re: Baudrate for dynamixels

    If you need to ask about signal quality, then it's unlikely that the added fragility of 4.5 Mbps will help you at all compared to something safer like 1 Mbps.

    To know what "too long" and "too...
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    Re: Conversion between angle and position values

    Unless you truly need 360 degrees of motion (not 359.9) you don't need wheel mode.
    You should just center the formula for "sent parameter from desired angle" at 0 degrees == 2048 sent parameter....
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    Re: Conversion between angle and position values

    The 360 degree position is valued at 0. Unfortunately, you can't actually get QUITE to that position -- you'll get to (4095*360/4096) degrees. Protocol 2.0 has a "multi-turn" mode that may help if...
  27. Thread: Temprature

    by jwatte
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    Re: Temprature

    For hobby servos, I have no idea whether they even have a thermal cut-off, or if they just let you run them until they die?

    150F (about 65C I think?) on the actual core/windings of the servos is...
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    Question(s) Re: RS485 logic level in Dynamixel servos

    For the Dynamixel servos (not Dynamixel Pro) the connector is rated at 3A continuous duty.
    The wires that come from Robotis are 22 gauge.
    This is slightly under-dimensioned for the heaviest duty...
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    Question(s) Re: RS485 logic level in Dynamixel servos

    Are you talking about the voltage on the RS485 bus itself?
    That's covered by the specification for RS485.
    Or are you talking about the host side, where the MCU talks to the transciever?
    The modern...
  30. Re: Is it normal that even with the same model, some dynamiels generate some sound?

    The rubber band has enough tension if you can pluck it with your finger and it sounds like "twang."

    Yes, torsion springs add more torque in one direction. But, if your robot is standing against...
  31. Re: Is it normal that even with the same model, some dynamiels generate some sound?

    Yes, that sounds exactly like an output that's under no load, and thus the PID controller is over-eager.
    Either add some load on the servo, or tune the PID to be sloppier (but then of course the...
  32. Re: Is it normal that even with the same model, some dynamiels generate some sound?

    The PID controller may be overshooting and re-correcting back and forth.
    Assuming this only happens when they're on, and torque is enabled.
    If you disable the torque, does the sound go away?
    ...
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    Re: OpenCM 9.04 and SPI

    In the Arduino API, "transfer" returns the byte that came back while it sent the argument byte.
  34. Re: Is it easy to change the adapter of those Robotis cables?

    Bob's Used Cars sell so many kinds of used cars and trucks, which one would you recommend?

    I recommend that you buy the one that seems to work for your application.

    If you have a hard time...
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    Re: Discharge rate of LIPO

    The difference between C=60 and C=75 doesn't matter at all.

    Also, at those levels, it's very likely the batteries are rated "optimistically" ("this is the largest possible current the battery...
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    Re: Discharge rate of LIPO

    The current capacity of a battery cannot "push" current into a circuit. The circuit draws as much current as it's designed/made to do at the voltage you provide it. If the power source cannot keep...
  37. Re: Is it easy to change the adapter of those Robotis cables?

    Net-like sleeves are called "cable sleeving" or "cable sheathing."
    https://www.mcmaster.com/cable-sheathing/
    https://amzn.to/30f5w8y
  38. Re: Is it easy to change the adapter of those Robotis cables?

    If you need custom cables, you'll want to buy the crimping kits for the connector series from the manufacturer, and your own wire to crimp the cables onto.
    The main challenge there is generally the...
  39. Question(s) Re: Attempting to send voltage to teenssy board via Arduino C++.

    I suggest the best forum to ask this in is https://forum.pjrc.com/forums/3-Technical-Support-amp-Questions
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    Re: Questions about powering

    Connecting the + pins on the batteries won't damage the motors, but it could damage the batteries, and perhaps the wiring between them, if the batteries are not charged to the same state.

    These...
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