USA
Asked — Edited

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PLEASE NOTE: THIS GUIDE IS OUTDATED.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

User-inserted image

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.

User-inserted image

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.

User-inserted image

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:

User-inserted image

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?

User-inserted image

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:

User-inserted image

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.

User-inserted image

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.

User-inserted image

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:

User-inserted image

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


ARC Pro

Upgrade to ARC Pro

Harnessing the power of ARC Pro, your robot can be more than just a simple automated machine.

#145  

@mtiberia I thought you could send from 1-180 not just 1-100 for servo position. My AX-12 servos move from 1-180. (Using a EZ-B V4)

#146  

Hi @mtiberia,

Thanks for you great help. I have tried your latest script, but still it says "oops i need to read the position again" again and again.

Also there is no full torque given to my Dynamixel servos as it is should be after, says "Don't worry I won't hurt them".

I'm so sorry, I really don't know what is the issues could be. FYI, I still am using 4 Dynamixel servos and my power source is 11.1V 2200mAh Li-Po Battery (1.5C).

I hope my Dynamixel servos is not broken. I don't really think it is broken, because when I try it on Dynamixel Configuration Tool, the servos works very smoothly.

Thanks again.

#147  

Sorry that was a typo it is 180. Ariffinastute try one Dynamixel servo at a time to track down the issue. Make sure they are set to communicate at 1000000 .

#148  

Hi @mtiberia

I'm sorry, I have tried to test one Dynamixel at a time, but still the result is same.

I have make sure that the communication, is as stated UARTInit(0,1,1000000).

#149  

@ariffinastute

Lets see if we can track this bug down. So when you ask Zira to find your servos all your servos are found and the settings are changed ?

If yes, then try this to test that you have a file to put the read positions in.

The easiest way is to check that it's in the folder. If its not, open a new window in ARC and write an EZ-Script to create a file and check that its there.

#150  

@mtiberia

First, I thank you for helping me on this situation. Yes, Zira did found 4 of my servo.

Despite Zira told that, she has found 4 of my servo and going to adjust their settings, but nothing happened to all of my servos, as it should be getting the reset torque, like on the script.

I stuck it here, I think the settings are not changed.

#151  

Do have the file in your folder?

#152  

@mtiberia

Yes, I do have the .txt file in my folder.

I have already changed the "path" from the original script of yours, to my own path of .txt file, which the example path ( "c:\Users\Mario\Desktop\Robot_Motion.txt" ) in the script are as stated in these three windows, Reading servo Position, Delete Motion File and Play.