How to interface with DX 117 using USB-2-Dynamixel adapter

[Rocky]

Hi,

I can communicate with my three DX 117s through dynamixel configurator, at a baud rate of 57143.

However, I can't seem to connect to the actuators using the 57600 baud setting through Hyperterminal nor Robot Terminal. I e-mailed Robotis about this issue and was told that the instruction packets have to be sent in hex, but Hyperterminal uses ascii communication.

I wanted to know if any of you out there knew how to talk to the servos directly ( the examples in the dx117 manual have a [dynamixel]: prompt).

Ultimately I'll have an application(built using LabView) access the actuators, but I wanted to first get basic communication established between the computer and the actuators.

Any help would be greatly appreciated.

Again, thanks in advance,
Rocky.

[Robo1]

Are you using the Cm-2 and the COM cable that came with it.

I run my through terminal at 115200. Using a USB to COM converter.

I just plug it in and it just works. When you hit the reset or power switch the terminal should produce some code. if it does then it's connected if it's set to the wrong speed then it will still return some strings but it's rubbish.

Hope this helps

What are you making with the DX's.


Bren

[Dewey]

The dynamixel configurator software does all the work of creating dynamixel command packets for you. When you connect via a Terminal Program you are just sending what you type to the dynamixel and receiving on your PC screen what the dynamixel transmits in response.

To talk meaningfully you must send properly constructed packets to the dynamixel. You cannot do this from the terminal as the required packets contains check code and non keyboard codes.

You must write a program on the PC to construct and decode packets sent/received( in accordance with the DX117 manual). Any computer language will do provided it gives you access to the usb port the USB2Dynamixel interface is attached to.

[Robo1]

Hi

I'm in the process of trying to hook up my gumstix to some DX-117, so would like to know how you got on. I've just ordered some max485's so next week will try and hook them up through ttys1. Any one else tried this, got any code .

A big thanks to JonHylands for your example code that helped me get SPI working on the gumstix and some other things.

Bren

[Rocky]

I have to say that it was quite easy to code once I understood how to construct and decode packets.

if you have any questions, please don't hesitate..

On another note, can you give me some info about the SPI interface you seem to have used? I'm in the process of acquiring a sensor with the SPI interface and am trying to decide between a Gumstix board or a Microcontroller. Any help would be greatly appreciated.

[Robo1]

Hi

I got the gumstix working using SPI only through bit banging. I tried using the SPI that's built in but after speeding a couple of hours on it gave up and used JonHylands example bit bang program and had it working in a couple of hours. I also had to bit bang the arduino side as there's no example of atmel chips in slave mode, they give you two lines of code for the receive and the reg configuration but had no joy getting them to work.

I find the gumstix really good. The only down side is the doc's if you go for a older boards there's plenty but I've got the new verdex board so none of the example code works as there different chips. This is the only problems I've found but a very annoying one as you have to take the example code and try and modify it to work. Got the GPIO ports working so at leased I can bit bang.

What did you implement you code on XP or linux did you use a max485 chip (I've just ordered one). Would love to look at some of your code.

What's the project.

Bren

[Rocky]

Hey Bren,

Thanks for all that info. I appreciate it.

I used LabView on Windows to program the actuators. LabView is a graphical programming tool produced by National Instruments. LabView is primarily an engineer's tool. Since my project was more engineering and less computer science oriented, I chose that path. I used the actuators to control the fin angles of a wind tunnel test model of a UUV(Unmanned Underwater Vehicle). This allowed me to change fin angles remotely, without shutting down the wind tunnel fan and changing the angles manually which is a very expensive and time consuming process. Furthermore, it is much easier to code up something with a fancy operator's GUI in LabView. So the code will all be graphical and you will need LabView and the USB2Dynamixel adapter to connect to the DX-117s.

Rocky

[NovaOne]

The DX117 looks like an awesome servo!

Can I ask what joints you guys are using it for?

At £99, a bot using totally dx117 would be surely be unstoppable.

Chris

[JonHylands]

If you think the DX-117 looks good, spend a little bit more money and get an RX-64. 64 kg-cm of torque (800+ oz-in).

- Jon

[NovaOne]

Amazing!
I just found HR18 which uses three RX-64's

HR18 was made my the Hajime Team for Robocup, SK is a Hajime team member and a Robosavvy member.

But what you guys (Rocky, Bren Dewey.......) using them for, on your Bioloids ?

Chris

[Robo1]

I use D-117 through out my biped.

I had a look at the RX-64's but the weight to torque was to high e.g. there very strong but weigh in at 106g that would be over 2.2Kg just in servos!

Bren

[SK]

HR18 was made my the Hajime Team for Robocup, SK is a Hajime team member [*] and a Robosavvy member.

Indeed
We´re using RX-64 for both knees and for the waist (allowing bowing motion). At first, we used DX-117s only, but experience showed that those were a little overwhelmed (mainly overheating) with the task in those locations.
RX-64s are heavy, expensive and a little slower than DX-117s though, so it depends on application and robot design (and wallet ) if they´re a good choice or not.
Also don´t forget about the relatively new RX-28, which is in the DX-117s size/power class (a bit bigger) and marketed to feature some improvements over the DX-117 by Robotis. Don´t know how the prices compare though.

/edit: [*] Slight correction: I´m member of the Darmstadt Dribblers, we use the HR18 robot made by the Hajime Research Institute. Unlike 2006, we didn´t attend RoboCup 2007 as the joint Darmstadt Dribblers & Hajime team. There are still close ties with Hajime Research Institute though.

[Rocky]

I'm not using my DX-117s for Bioloids. I am actually using them as plain old servos that control fins in an underwater vehicle.

I wish I had more free time to get into the whole humanoid stuff.

Rocky.

[NovaOne]

Thanks for the replies guys.

Rocky:

I wish I had more free time to get into the whole humanoid stuff.

I know what you mean, thats why i bought a ready designed kit robot.

SK, How "intelligent" (autonomous) is your HR18 when playing soccer?

Bren, no one stands a chance against you at ROBOtic'07

Chris

[SK]

SK, How "intelligent" (autonomous) is your HR18 when playing soccer?

The robot is completely autonomous when playing soccer. The only signals it might receive from "outside" are gamestate signals (e.g. mainly "kick off"). The robots are allowed communicate with each other over WLAN though, ours use this to negotiate their roles (striker, goalie, defender) and exchange information about ball, own position etc.