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Thread: Testing the MX-64T and MX-106T

  1. #21

    Re: Testing the MX-64T

    I think that fan may be slightly too large to fit well between the flanges for the nuts; especially if you use screws that stick out from the nuts when fully tightened.
    Anyway, I've gotten to the conclusion that it's better to not load the servos to the point where they need the cooling. A strong torsional spring or two on the loaded joints to counter-act gravity would probably be a better investment.

  2. Re: Testing the MX-64T

    Hey zenta,
    As you have already tested the Mx-64, just wanted to confirm something; will it be ok to use Mx -64s for a biped that weighs of 6 kg in all?

  3. #23
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    Re: Testing the MX-64T

    Hi,

    That's impossible to answer without knowing all dimensions, especially the dimensions of the leg segments. I don't have much exp with biped's (only one so far). The one I have has a weight of about 1,6kg and I'm using the Hitec 5645's RC servos. They are rated to about max 10-12kg/cm. At the moment I don't remember what's their dynamic torque is, I believe I did a test one time..

    I would recommend taking a look at the Jimmy robot. It's about 6 kg and they are using the MX-106 for the legs I think.
    Kåre Halvorsen aka Zenta
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  4. Re: Testing the MX-64T

    Knowing that the stall torque is actually about half of what it is rated, would it be possible to use the "Present Load" value to determine the actual torque on the motor? For example, a value of 1023 for present load is actually about 3 Nm. I know the manual does not recommend it per this note:
    Notes: Current load is inferred from the internal torque value, not from Torque sensor etc.
    For that reason, it cannot be used to measure weight or torque; however, it must be used only to detect which direction the force works.

  5. #25
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    Testing the MX-106T

    Hi,

    Is it possible to change the main title of a thread?

    For some weeks ago I got my hands on some MX-106T , so today I did some torque testing.

    It certainly is stronger than the MX-64T, of course.. @12v the stall torque was about 45kg. Under the same load as the stall torque of the MX-64T (about 30 kg), the MX-106T handled the load very well. Even 40 kg/cm worked ok, but the temperature started raising relative fast. I didn't do the same thorough temperature test as I did on the MX-64. And I didn't do any max holding torque test, didn't dare..

    For the fun of it I did a stall torque test on a Hitec HSR-5990TG and a HS-5645MG servo. The stall torque for a 5990 is about 12 kg/cm @7,4v and about 6kg @6v for the 5645. So you can say the MX-106 is a big upgrade, lol.

    Anyway, I do find the numbers interesting for my next hexapod project. I believe I'll go for the MX-64 for the coxas and tibias, and the MX-106 for the femurs. Under normal conditions at default posture the femurs do get the highest load on a hexapod. The tibia get the highest load when moving the foot close to the coxa.
    Last edited by Zenta; 10-05-2014 at 01:22 PM.
    Kåre Halvorsen aka Zenta
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    Re: Testing the MX-64T and MX-106T

    What do you want the title to be? No prob!

  7. #27
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    Re: Testing the MX-64T and MX-106T

    Quote Originally Posted by Tyberius View Post
    What do you want the title to be? No prob!
    Kevin has already helped me out. I just wanted to include the MX-106T in the title.
    Thanks.
    Kåre Halvorsen aka Zenta
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  8. Re: Testing the MX-64T

    Quote Originally Posted by tician View Post
    jwatte lost several MX-64 partly from using 4S LiPo voltages, but I've run a DARwIn-OP with a 4S LiFePO4 without any obvious damage.
    I have only used Lipo batteries on the Bioloid. Why jwatte lost several MX-64 partly from using 4S LiPo voltages? Since some of you have done testings on the MX-64 and MX-106, what batteries do you recommend for a big robot built using such actuators?

  9. #29

    Re: Testing the MX-64T and MX-106T

    Why jwatte lost several MX-64 partly from using 4S LiPo voltages?
    It was somewhat unclear for a long time, but the most likely chain of events is this:

    1) While trying things with my IK engine, and the servos configured at full max torque, the servos moved into interference. I turned them off withing 3 seconds when this happened, which is faster than the built-in overload turn-off (which is 7-8 seconds I'm told by Robotis.)

    2) Because I was using fully charged 4S LiPos, these 3 seconds were enough to make the motors overheat and partially destroy themselves. They would still move, but they would rub against their internals, and even at idle, they would draw one amp of current.

    3) Because of this, the motors would send bad spikes onto the voltage and TTL buses. This would eat away at the buffers on the TTL bus on nearby servos, rendering their PCBs broken.

    4) Because I didn't know exactly what the problem was (the "half-destroyed" servo that moved but had motor problems,) some servos acted like a "vampire" that ate other servos when connected to the same bus.

    I had several round trips with Robotis, having motors and PCBs exchanged, but the problems came back because the "vampire" servos passed local self-tests and weren't sent in for fixing. Also, I had to pay for the motors (the PCBs were covered by warranty.) I find this a little annoying, because the original problem was that the built-in overload protection was insufficient at rated voltage (fully charged LiPo 4S -- which they had previously said was supported.) But, at least I learned to not trust specifications :-)

    When using 3S LiPo, everything runs smoother. I think I could run 4S LiPo without problems now, because the IK engine and leg configuration is debugged and working fine, but as I already have something working now, I'm not changing it.

    Advice: While developing IK code, and changing things that may make the servos move into interference, use lower voltage, and configure the "max torque" register to something perhaps 50% of full torque, and be very quick with the power-off switch if something goes wrong!

  10. Re: Testing the MX-64T and MX-106T

    Quote Originally Posted by jwatte View Post
    Advice: While developing IK code, and changing things that may make the servos move into interference, use lower voltage, and configure the "max torque" register to something perhaps 50% of full torque, and be very quick with the power-off switch if something goes wrong!
    Sounds like good advice. When you're talking about "interference", is that where the servo is trying to push into a position that the attached mechanics doesn't allow? Is there a reason the automatic shutoff is so slow?

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