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Sudo'S Guide To Dynamixels

PLEASE NOTE: THIS GUIDE IS OUTDATED. BADLY. (remind me later to fix this and spiff it up a bit, please)

So, you finally have your EZ-B v4. You love it already, and you're ready to hook this baby up to some sort of Dynamixel powered creation. You go to plug everything in, and - wait. You have no idea how to set those Dynamixels up.

Well, I do, and I'll show you how.

SECTION 1: GETTING TO KNOW DYNAMIXELS

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Dynamixels are intelligent servos that can track not only position, but temperature, speed, and load. The servo can automagically shut itself of incase of a failure. These servos are also incredibly strong. But there's one feature in particular that is useful, but at the same time a little hard to wrap your head around. In this section, we will cover daisy chaining and other features of the AX-12A Dynamixel; however, most of the servos in the Dynamixel family work exactly alike, so this guide can help you with most models.

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On the back of all of your Dynamixels, you will notice a couple things. A place for a bolt, a light, two wire ports, and the ID. Lets go over all of them so you know what they do:

Light - Blinks once when turning on. If the light is flashing, there is a failure of some sort.

Screw hole - Allows you to attach the Dynamixel to a bracket.

Wire ports - Allows you to connect to other Dynamixels, in a long strand of servos, both to and from other Dynamixels. This means both ports work the same way, which means it doesn't matter which side is plugged in. (see image below)

ID - What the EZ-B and ARC address the Dynamixel as.

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PART 2: CONNECTING YOUR DYNAMIXELS TO THE EZ-B

All Dynamixels must plug into port D5 in order to properly work. This means that all of your Dynamixels must plug into one port. If you have more than one strand of connectable Dynamixels, you will have to use a Dynamixel splitter hub, like this one here:

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You can either run a cable to the EZ-B via a power base or via the powered splitter. I advise that you use only one, as using both at once can brown out the EZ-B.

Q: So, now that that's done, what power supply do I use? Mains or a battery pack?

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A: Both will work just fine. Just make sure you have an adequate power supply at around 10v.

"But wait!" you scream. "Dynamixels can run at 9v-12v! Why 10v?"

Because voltage is gradually lost over time depending on how many servos you're running at once, as well as when the EZ-B is powered on. The more servos you have, the higher you should up your voltage to get a steady 10v overall.

So, if you have power running to the EZ-B, Dynamixels set up to port D5 (as well as the optional splitter) you should have something resembling this:

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Now that you're powered on, lets move into ARC and get your Dynamixels running.

PART 3: OPERATING THE DYNAMIXELS WITH ARC

Connect to your EZ-B as usual (We won't be covering connections in this guide). Bring up a servo control panel and go to the servo configuration screen as shown below.

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Click the Dynamixel box and scroll down until you see the ID of the Dynamixel you want to move (the ID on the back of the servo). In this demonstration, we'll be selecting Dynamixel AX18.

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Select it and save the configuration. Congrats, you just set up your first Dynamixel in ARC! It should operate just like a normal servo. This applies to all servo control functions.

PART 4 (EXTRA): ASSIGNING A NEW ID TO BLANK SERVOS

When you buy a Dynamixel that doesn't come in the kit, the ID sticker will sometimes be blank, which means it hasn't be assigned a "real" ID. However, a tool in ARC can give Dynamixels a new ID.

First, open up the Dynamixel Config. control in ARC. You should see something similar to this:

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All blank servos are assigned ID 1. If you have a dynamixel with the ID 1 already, remove it before you proceed. Simply choose the new ID you want (in this case, AX18) and press execute. ARC will assign it a new ID. That's it, you're done! You can also write the ID on the blank tag if so desired.

GUIDE LAST UPDATED: 12/9/2014


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Belgium
#41  

oldbotbuilder

whit dynamixel manager you can see all.

#43  

Sudo,

Your bioloids seem to have the best walking motion I've seen so far. Though they only took a few steps. They have a very natural motion about them.

Are you using some sort of IMU stabilization?

Can you send another video of them walking some more?

Thanks,

Bill

#44  

Do you mean nomad's video? I have yet to upload a video of shogun walking. However, the walking action that i've created is probably the best you can get without a gyro, you just need a different knee configuration. If you want, I could upload a video sometime this weekend.

PRO
Belgium
#45  

hi averyone

sudo i refirmwire the servo and the cm-510 ,still turning like a wheel. love to see your video too.

#46  

Hey SUDO and anyone else that would like to control the AX12 servo with EZ script. I've attached a EZ Script example that you can experiment with.

Only thing DJ hasn't got around to fixing the issues with the UART so if 34,40and 92 are TX or RX EZ script will stop and show an error. Again DJ is aware of this.

AX12ControlEZB.EZB

To read position of the AX12 servo you need to add a connection to D6.

#47  

Forgot to mention that if you have been using ARC to control the AX12 servo you have to run the script named "resetting return level " in the example.

Again there's a bug in ARC that changes the way the dynamixel communicates with EZ B and the control table for setting the speed of the servos. These bugs were reported to DJ in my earlier posts.

#48  

@mtiberia

wasn't that fixed? I've been having no trouble with my dynamixels not responding to controls (when they have proper power:D) the only lingering problem I've had is the torque being turned down instead of speed.