RoboSavvy Forum

Say I just want to buy some servos..

2007-01-10T07:17:33+01:00

Well look at this!

http://robosavvy.com/modules.php?name=F ... opic&t=305

Someone already started looking down this route back in May.

Statistics: Posted by billyzelsnack — Wed Jan 10, 2007 7:17 am

Say I just want to buy some servos..

2007-01-10T06:42:39+01:00

Ok. Here's the first sniff result. It goes TX RX TX RX etc. This is from going into the behavior program and downloading an example (not the motion) and telling it to play. Then I hit start on the CM-5 and it goes. I don't think all of that is visible in the log though.

--------------------------

Recorded and exported to HTML by SmartSniff.

HEADER INFO INTO FILE C:\Users\billy\Documents\Default.mpsl
File version: 4.30
Max supported version: 4.30
PORT - COM

Speed switching: #1
BaudRate=57600
Parity=0
StopBits=0 (1 bit)
ByteSize (bits)=8
As binary (DCB)=1C 00 00 00 00 E1 00 00 01 40 00 00 00 00 64 00 64 00 08 00 00 11 13 00 1A 00 00 00

000000 (00000), 0 ms

2A 2A 2A ***

000001 (00000), 203 ms

02 02 02 ...

000002 (00001), 2406 ms

2A 2A 2A ***

000003 (00001), 2609 ms

02 02 02 ...

000004 (00002), 2609 ms

23 23 23 23 23 23 23 23 23 23 23 23 23 23 23 23 ################
23 23 23 23 23 23 23 23 23 23 23 23 23 23 23 23 ################
23 23 23 23 23 23 23 23 23 23 23 23 23 23 23 23 ################
23 23 ##

000005 (00002), 2813 ms

02 02 02 FF ....

000006 (00003), 2813 ms

23 23 23 23 23 23 23 23 23 23 23 23 23 23 23 23 ################
23 23 23 23 23 23 23 23 23 23 23 23 23 23 23 23 ################
23 23 23 23 23 23 23 23 23 23 23 23 23 23 23 23 ################
23 23 ##

000007 (00003), 3016 ms

0D 0A 0A 20 53 59 53 54 45 4D 20 4F 2E 4B 2E 20 ... SYSTEM O.K.
28 43 4D 35 20 42 6F 6F 74 20 6C 6F 61 64 65 72 (CM5 Boot loader
20 56 31 2E 33 31 29 0D 0A 20 2D 20 23 23 23 23 V1.31).. - ####
23 23 23 23 23 23 23 23 23 23 23 23 23 23 23 23 ################
23 23 23 23 23 23 23 23 23 23 23 23 23 23 23 23 ################
23 23 23 23 23 23 23 23 23 23 23 23 ############

000008 (00004), 3219 ms

0D 0D ..

000009 (00004), 3422 ms

0D 0A 20 2D 20 0D 0A 20 2D 20 .. - .. -

00000A (00005), 3422 ms

0D 6C 64 20 61 30 30 30 0D .ld a000.

00000B (00005), 3625 ms

0D 0A 20 2D 20 6C 64 20 61 30 30 30 0D 0A 20 57 .. - ld a000.. W
72 69 74 65 20 41 64 64 72 65 73 73 20 3A 20 30 rite Address : 0
30 30 30 41 30 30 30 0D 0A 20 52 65 61 64 79 2E 000A000.. Ready.
2E .

00000C (00006), 3625 ms

04 06 04 E4 02 06 04 05 04 80 00 C8 20 00 04 08 ............ ...
00 00 01 04 4E 00 81 00 C8 20 00 04 02 00 00 01 ....N.... ......
04 F9 00 81 00 C8 20 00 04 01 00 00 01 04 46 01 ...... .......F.
81 00 C8 20 00 04 04 00 00 01 04 A8 01 81 00 C8 ... ............
20 00 04 10 00 00 01 04 C7 02 01 04 09 00 02 00 ...............
64 29 04 FF 00 02 00 64 28 04 00 00 02 00 C8 18 d).....d(.......
04 14 00 06 04 18 04 02 00 C8 18 04 15 00 06 04 ................
18 04 02 00 C8 18 04 16 00 06 04 18 04 06 04 34 ...............4
04 02 00 64 25 04 00 00 80 00 64 25 01 04 00 00 ...d%.....d%....
00 01 04 A6 00 80 00 64 1B 02 04 32 00 00 01 04 .......d...2....
EA 00 01 04 88 00 02 05 00 00 00 64 25 02 00 C8 ...........d%...
18 04 14 00 06 04 18 04 03 05 00 00 05 00 00 01 ................
04 01 00 02 00 C8 18 04 15 00 06 04 18 04 80 05 ................
00 00 01 04 00 00 00 01 04 B8 00 02 00 C8 18 04 ................
16 00 06 04 18 04 01 04 81 00 02 00 C8 18 04 17 ................
00 06 04 18 04 01 04 81 00 02 00 64 29 04 FF 00 ...........d)...
02 00 64 28 04 04 00 02 00 C8 18 04 28 00 06 04 ..d(........(...
18 04 80 00 64 1B 02 04 32 00 00 02 00 C8 18 04 ....d...2.......
29 00 81 00 64 1C 02 04 50 00 00 02 00 C8 18 04 )...d...P.......
2A 00 81 00 64 1A 02 04 50 00 00 02 00 C8 18 04 *...d...P.......
2B 00 01 04 12 01 02 00 64 29 04 FF 00 02 00 64 +.......d).....d
28 04 01 00 06 04 34 04 80 00 C8 18 00 04 0B 00 (.....4.........
00 02 00 C8 18 04 0E 00 82 02 00 C8 18 04 0C 00 ................
06 04 18 04 02 00 64 25 04 00 00 80 00 64 25 03 ......d%.....d%.
04 03 00 00 01 04 7B 01 80 00 64 1B 03 04 C8 00 ......{...d.....
00 02 00 C8 18 04 0D 00 82 02 00 C8 18 04 0B 00 ................
06 04 18 04 01 04 58 01 02 00 64 29 04 FF 00 02 ......X...d)....
00 64 28 04 03 00 02 05 01 00 04 64 00 06 04 3B .d(........d...;
02 02 00 C8 21 04 18 00 06 04 26 04 80 00 64 1B ....!.....&...d.
02 04 32 00 00 01 04 FB 01 80 00 64 1A 02 04 3C ..2........d...<
00 00 01 04 2B 02 80 00 64 1C 02 04 3C 00 00 01 ....+...d...<...
04 33 02 06 04 57 02 01 04 CC 01 06 04 73 02 02 .3...W.......s..
00 C8 21 04 10 00 06 04 26 04 80 00 64 1A 02 04 ..!.....&...d...
32 00 00 06 04 8F 02 82 06 04 AB 02 02 00 C8 21 2..............!
04 10 00 06 04 26 04 01 04 CC 01 06 04 8F 02 01 .....&..........
04 CC 01 06 04 AB 02 01 04 CC 01 80 05 01 00 05 ................
04 00 00 00 06 04 11 04 02 00 C8 18 04 4E 00 02 .............N..
05 01 00 04 00 00 07 80 05 01 00 05 04 01 00 00 ................
06 04 11 04 02 00 C8 18 04 3C 00 02 05 01 00 04 .........<......
01 00 07 80 05 01 00 05 04 02 00 00 06 04 11 04 ................
02 00 C8 18 04 45 00 02 05 01 00 04 02 00 07 80 .....E..........
05 01 00 05 04 03 00 00 06 04 11 04 02 00 C8 18 ................
04 57 00 02 05 01 00 04 03 00 07 80 05 01 00 05 .W..............
04 04 00 00 06 04 11 04 02 00 C8 18 04 60 00 02 .............`..
05 01 00 04 04 00 07 02 00 64 29 04 FF 00 02 00 .........d).....
64 28 04 02 00 02 00 C8 18 04 18 00 06 04 18 04 d(..............
01 04 09 00 80 00 01 08 00 04 00 00 00 02 00 01 ................
08 04 FF 03 80 00 02 08 00 04 00 00 00 02 00 02 ................
08 04 FF 03 80 00 03 08 00 04 00 00 00 02 00 03 ................
08 04 FF 03 80 00 04 08 00 04 00 00 00 02 00 04 ................
08 04 FF 03 80 00 05 08 00 04 00 00 00 02 00 05 ................
08 04 FF 03 80 00 06 08 00 04 00 00 00 02 00 06 ................
08 04 FF 03 80 00 07 08 00 04 00 00 00 02 00 07 ................
08 04 FF 03 80 00 08 08 00 04 00 00 00 02 00 08 ................
08 04 FF 03 80 00 09 08 00 04 00 00 00 02 00 09 ................
08 04 FF 03 80 00 0A 08 00 04 00 00 00 02 00 0A ................
08 04 FF 03 80 00 0B 08 00 04 00 00 00 02 2A 2A ..............**
2A *

Statistics: Posted by billyzelsnack — Wed Jan 10, 2007 6:42 am

Say I just want to buy some servos..

2007-01-10T06:13:02+01:00

I could not get any serial sniffers to work under Vista. I'll try on XP tomorrow.

I did verify that a regular old terminal emulator will work in place of the 'robot terminal' program.

I'll need to get a sniffer working before I can go much further. I was messing with sending in 'program' and 'play' mode. Sometimes a 'go' command would work at a slow speed, but it would only work once. There are probably a bunch of codes that can do various things that I'll need to know.

hmm. Maybe I should look around and see if anyone else already has done this work.

Statistics: Posted by billyzelsnack — Wed Jan 10, 2007 6:13 am

Say I just want to buy some servos..

2007-01-10T04:32:36+01:00

hmm. Page 114 of the users guide shows the same baud table that the ax-12's has.

"The baud command changes the baud rate of the CM-5 itself and all the Dynamixels that are connected to the CM-5"

Sounds promising. Now I just need to figure out how to send/receive data. Seems easy enough to sniff considering you can see exactly what is happening with the terminal program. Though maybe you can and I just have not found out where it tells me how to yet.[/img]

Statistics: Posted by billyzelsnack — Wed Jan 10, 2007 4:32 am

Say I just want to buy some servos..

2007-01-10T03:25:18+01:00

Hmm. I'll check into the 56k max. If that's the case then I think I'll be doing some USB to 485 research tonight.

Statistics: Posted by billyzelsnack — Wed Jan 10, 2007 3:25 am

Say I just want to buy some servos..

2007-01-10T00:51:55+01:00

that sounds good. will be using the CM-2 for the time being (have one on order) then will make my own controller. As the DX can run at 1Mps should be able to run at least 400 loops per sec which should make for a pritty good control system.

thanks bren

Statistics: Posted by Robo1 — Wed Jan 10, 2007 12:51 am

Say I just want to buy some servos..

2007-01-09T19:35:53+01:00

Well, the refresh rate you will get will be different than what we can get. The DX-117 uses RS-485, and I have no idea what controller you're using or how it communicates with a PC.

However, since the DX-117 uses the same type of command language, talking to 7 servos and getting the 3 values back from each, 200 times per second would take a minimum bandwidth of about 340 Kbps.

- Jon

Statistics: Posted by JonHylands — Tue Jan 09, 2007 7:35 pm

Say I just want to buy some servos..

2007-01-09T18:55:04+01:00

A quick question:

what resolution are you guys seeing with say 7 servos in a chain. writting position to each and reading the data e.g. position force. this is with nothing else runnig o the proc apart from these commands.

I want to know as I'm going to start righting a closed loop system for my DX-117 and what to know the res any thing above 200/s would make me very happy.

cheers bren

Statistics: Posted by Robo1 — Tue Jan 09, 2007 6:55 pm

Say I just want to buy some servos..

2007-01-09T18:35:53+01:00

From what I've seen, the CM-5 is limited to 57,600 in communications with the PC.

If you are updating 18 servos, using the sync_write command, with just position (2 bytes per servo), you're looking at 3 bytes per servo plus 7 bytes overhead, which is 43 bytes total. You get 6 bytes back, so you're looking at (roughly) 50 bytes per cycle, or 500 bits.

If you weren't interested in any feedback, you could theoretically do 100 frames per second, although in reality there is a delay between sending and receiving.

However, there is no sync-read command, so you're stuck reading the bytes from each servo, one at a time. A read instruction is 8 bytes down, and you would get back 6 bytes plus the number of bytes you're reading from that servo. If all you wanted was position, that would be 8. If you want position and torque, you need to read speed as well, so you're up to 12 bytes total response.

Assuming the latter, you're looking at 20 bytes per servo, which is 360 bytes for all 18.

So, the total is now 410 bytes per cycle, which is 4100 bits (roughly). You're down to 10 frames per second, which is still doable, but slow.

Note that this analysis is based on the assumption that the CM-5 does nothing to the bytes you send and receive, which may not be the case.

All this is why I am developing a wifi link to the Bioloid. That will give me a straight-through link at 1.0 Mbps to the bus from my PC, for about $200 in hardware.

- Jon

Statistics: Posted by JonHylands — Tue Jan 09, 2007 6:35 pm

Say I just want to buy some servos..

2007-01-09T18:17:31+01:00

I don't think you'll be able to make it free-wheel nicely since it doesn't free-wheel nicely with the power off.

Ok.. So I've built the humanoid and I'm ready to start working on my own software. My first project is to look into the latency of controlling the servos from my computer. What I want to do is transmit the humanoid demo motion positions on the fly while reading the feedback at the same time.

What would be ideal for now would be to do this via the CM-5. Is this even possible? I've not seen any specs for the CM-5 command set, maybe I just missed them?

Eventually I would like to build a USB->Dynamixel interface (or maybe several to cut down on the latency of many servos), but for now it would be nice to just use the CM-5.

Statistics: Posted by billyzelsnack — Tue Jan 09, 2007 6:17 pm

Say I just want to buy some servos..

2007-01-09T03:23:07+01:00

Joe wrote:
Great work, Jon!

A neat demo/test would be to set up two AX-12s, and use one as an input to control the other one. That is, set that one up to offer little resistance to outside movement (I assume there is some way to do this?), and have your code continually read its position, and set the second servo to the same position. Then wiggle the first around by hand and see how well the second one tracks your every move.

Best,
— Joe

You mean like this?

http://www.bioloid.info/tiki/tiki-download_file.php?fileId=48

The driving servo is actually quite hard to turn - I'm sure I'm missing something with respect to a setting I can change to make it truly free-wheel.

I've changed the following values:

14, 15 (max torque) - 0
24 (torque enable) - 0
34, 35 (torque limit) - 0

Are there others I need to change?

- Jon

Statistics: Posted by JonHylands — Tue Jan 09, 2007 3:23 am

Say I just want to buy some servos..

2007-01-08T18:40:37+01:00

Great work, Jon!

A neat demo/test would be to set up two AX-12s, and use one as an input to control the other one. That is, set that one up to offer little resistance to outside movement (I assume there is some way to do this?), and have your code continually read its position, and set the second servo to the same position. Then wiggle the first around by hand and see how well the second one tracks your every move.

Best,
— Joe

Statistics: Posted by Joe — Mon Jan 08, 2007 6:40 pm

Say I just want to buy some servos..

2007-01-08T01:10:14+01:00

Jon,

Have to say congrats - that is sweet

Pev

Statistics: Posted by Pev — Mon Jan 08, 2007 1:10 am

Say I just want to buy some servos..

2007-01-08T00:27:43+01:00

Yeah, I can read all/any of the registers. I'm in the process right now of putting together another GUI, with a torque gauge, position, and speed indicators.

I have a screenshot of the GUI I was playing with here:

http://www.huv.com/blog/2006/12/ax-12-administration.html

This GUI shows me all the registers for a servo, and allows me to change the writable ones by double clicking on the value and entering a new value.

With this, I can play with the various parameters, and when I've got it set up the say I like, I can export the changeable values to a file, and then import them to update the other servos, one at a time, so I don't have to type in every value 18-20 times.

- Jon

Statistics: Posted by JonHylands — Mon Jan 08, 2007 12:27 am

Say I just want to buy some servos..

2007-01-08T00:10:11+01:00

Sweet.. Do you have the feedback working too? You could add another line to your widget that shows where the servo actually is.

Statistics: Posted by billyzelsnack — Mon Jan 08, 2007 12:10 am