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    Re: Making a mechanical gyro?

    How fast can you spin that encoder before it starts losing steps?
  2. Thread: Malum IK

    by jwatte
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    Re: Malum IK

    [quote]More crammed than this 33x50mm thing?[/COLOR]

    Probably not on average, but the dual-rail buck converter area, and the video-switch-and-general-inverter area are both quite full!
    ...
  3. Thread: Malum IK

    by jwatte
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    Re: Malum IK

    7632

    Not sure this is all that useful. The board is fairly crammed, so it's hard to tell from the CAD. Maybe I'll remember to take a photo when I get home.
  4. Thread: Malum IK

    by jwatte
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    Re: Malum IK

    They didn't have QFN footprints to match, so I constructed them in KiCad using the recommended dimensions from the data sheets. Also: I use "QFN" to mean all the packages with pads on the bottom but...
  5. Thread: Malum IK

    by jwatte
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    Re: Malum IK

    I have used exactly this circuit to interface between Teensy 3.2 and 3.5 and the DXL bus, yes!

    The RX pin has a 560 Ohm / 1 kOhm resistive divider to translate the 5V of the buffer chip down to...
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    Re: Making a mechanical gyro?

    Oooh, that'd be awesome!
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    Re: servo sequencing program? bipedal walker.

    Those are RC servos, using PWM control. You can generate such pulses from any of the Arduino boards, using the Servo library.
    I'd recommend using a Teensy, but really, any of the Arduino-like boards...
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    Re: Mech Warfare at the NorCal Robotics Expo

    I'd like to attend if possible, too!

    Also, I'd like to help a bit, perhaps with scoring plates or somesuch. Maybe we can make an order to Macrofab for the manufacture?
    I may have one or two spare...
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    Re: Making a mechanical gyro?

    That's what the magnetometer (and ideally also a GPS input) is supposed to help you solve, using some kind of Kalman conditioning.
    Another option is to mount the IMU on a thick sorbothane substrate....
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    Re: Making a mechanical gyro?

    Optical flow from a camera to detect movement and orientation isn't half bad!
    You could get a NVIDIA Jetson something-or-other and a camera for it; they already have some software demos to show how...
  11. Thread: Pronking robots

    by jwatte
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    Pronking robots

    https://youtu.be/G6fMV1UPzkg?t=29
  12. Thread: mjbots quad A0

    by jwatte
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    Re: mjbots quad A0

    Here's another robot that's pronking: http://news.mit.edu/2019/mit-mini-cheetah-first-four-legged-robot-to-backflip-0304
    (I imagine you've already seen that one, but I hadn't!)
  13. Thread: mjbots quad A0

    by jwatte
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    Re: mjbots quad A0

    I had to look up "pronk."

    Also: that looks INSANE!!!! (in a good way.)
  14. Thread: Temi

    by jwatte
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    Re: Temi

    What do you mean by "personnel teleportation device" ? With two 50W motors, I don't think a human being is supposed to ride on it?
    Maybe this is a competitor to telepresence robots like "double"...
  15. Question(s) Re: DYNAMIXEL MX-28 Velocity Mode is Not Working Properly

    How long does it keep moving slowly? Forever?

    Which value do you write to the goal velocity register to write a "zero" target? If you bump it up or down by one, does it stop the motor?
  16. Re: Question about a particular omnidirectional robot design

    I've heard it called "omnidirectional steering" but I don't know if there's a more accepted name in practice.
    Given that these aren't particularly common in industry, I wouldn't be surprised if...
  17. Question(s) Re: Can't connect to Dynamixel MX-106T servo on dynamanager

    Do you have a USB2Dynamixel or perhaps a U2D2?
    Then you might be able to use the Dynamixel Wizard to see if you can scan to find the servo.
    You can also attempt to update the firmware of the servo....
  18. Thread: mjbots quad A0

    by jwatte
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    Re: mjbots quad A0

    When you crank up the speed, it looks quite scary!
    Very nice video, too -- you're having so much fun.
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    Question(s) Re: 4 Dof Hexapod Torque calculations

    The link posted the first time, but all I see is a unit converter, nothing that analyzes the weight distribution of a supported legged robot.
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    Project Re: More Mule then Rover?

    Now to start the engine only when battery voltage falls below X, and then stop it when voltage reaches full charge again :-)
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    Re: Maker Faire 2019 Mech Warfare

    Nice!
  22. Re: with problem on Arduino IDE

    I think the problem is in ROS code, not Dynamixel code. USBSerial is not (necessarily) a HardwareSerial.
    They might, for example, want to use Stream instead?
    This is the same in Teensy 3/4, btw:...
  23. Re: with problem on Arduino IDE

    It looks like the ROS library is hard-coded to expect a "real" serial port, which is reasonable on old-school Arduinos, but not later ones like the Leonardo (or the Teensy 3, or the OpenCM 9.04)
    The...
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    Re: Maker Faire 2019 Mech Warfare

    "The BBs go in here" :-)

    The one extra thing I'd wish for these movies is a quick show of which mech has what name somewhere in the beginning. Would make it easier to remember for those of us who...
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    Project Re: More Mule then Rover?

    Yeah, I've noticed that grass is a motor killer.
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    Project Re: More Mule then Rover?

    I'd love to see that steering setup built :-)
  27. Question(s) Re: Dynamixel XM430-W210-T bricked after firmware update

    Yeah, I think the USB2Dynamixel doens't even work anymore with the new software. I had servos that would not update correctly, but when I sent them in, they claimed they updated fine.
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    Project Re: More Mule then Rover?

    I imagine you could use a diode and a 12V DC converter to keep the 12V battery topped off while the motors aren't stalling out? Or do you think you'll just have < 15V on the 24V rail most of the...
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    Question(s) Re: OpenCM sketch upload problems on virtualbox

    Virtual machines and USB devices are a right pain, because of the way that the hardware and host and guest OS have to cooperate to route the USB device to the virtual machine. VMWare has a custom...
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    Project Re: More Mule then Rover?

    I would look into a DC/DC converter that outputs 12V 10A from the 24V rail instead. A little bit of electronics is generally lighter and more robust than anything mechanical ...
  31. Question(s) Re: Dynamixel XM430-W210-T bricked after firmware update

    Flipping the switch to cut power may not work right if it also disconnects the board from the PC.
    I would recommend literally un-plugging and re-plugging the wire into the servo when the wizards...
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    Project Re: More Mule then Rover?

    Nice!

    Also, looks like just the right size to run that 2.4 kW generator. And at $100, it sounds like you got a good deal!
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    Question(s) Re: Using Dynamixel AX-12 A

    After the servos fail, can you move them by manually moving the arm? Does the red LED blink?
    It's quite possible the servos detect overheating and shut down.
    You should be able to read back the...
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    Project Re: More Mule then Rover?

    Love it :-)
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    Project Re: More Mule then Rover?

    Better watch out! If you're not careful, you'll end up with a robotic farm to sustain you through the coming climate apocalypse, and then where would you be?
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    Project Re: More Mule then Rover?

    Good thing this is not your lawn mower robot :-)
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    Project Re: More Mule then Rover?

    Using a bigger controller is not a problem in itself -- it just gives you more margin for error. The only reason to use a smaller controller is if space or dollars are a constraint. FWIW, I've...
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    Project Re: More Mule then Rover?

    Very nice!

    But will it have four-wheel independent steering? :-D
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    Question(s) Re: Using Dynamixel AX-12 A

    Yes, you need to configure their ID so they match the ID of the current servos in the arm.

    Btw: You should be able to use Dynamixel Wizard and hook up just one servo at a time. Scan the bus to...
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    Re: 2 USB Connections on Teensy 3.5 or LC

    Yeah, just add one of those cheap Chinese USB serial dongles, and wire it to one of the serial ports on the Teensy.
    Beware that, for that setup, making sure the baud rate matches up is actually...
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