Testing p.Brain and SMB with Lexapod

[paulp]

The Story so far...

Lexapod is a V4b/V5 wannabe cut from clear polycarboate and uses Kondo Servos.

The footprint of the SMB is the same as several other boards on the market so mounting it was simple.


By pajp, shot with Digimax L85 at 2008-08-08

The layout of the servo connections also lends itself very nicely to a semi-organised cable route. I am terrible with this sort of thing myself.


By pajp, shot with Digimax L85 at 2008-08-08

As can be seen from the image, the servo connections are laid out in groups of 3 which is pretty standard for most hexapod legs.

To the left of the image is my Sparkfun BlueSmirf bluetooth serial link that I intend to use with the board. This will allow me to control through my PDA, when I get that far. As with most of us I am already planning way too far ahead.

Well, I'll bolt the thing back together now and get on to the setup...

[paulp]

Setup and other things

Okay, Hyperterminal initially had problems but is fixed now, Tera term is a free comms package of which there are several flavours. Version 3 and above are Vist compatible whereas Hyperterminal is not longer included with windows..

Anyway, with comms program open, power cycling the p.Brain gives you the initial boot screen and basic options.

The first thing is calibration. This is basically moving the hardware joints to a position that the firmware can understand. In this case its all at right angles which should make life easier. The manual gives some very clear diagrams of each angle and how to set it.

There are several ways setup can be achieved but I carried out the following...

Entering the calibration gives you the following screen



By pajp at 2008-08-08

I selected the leg, in this case leg 1 and start the refresh. This applied power to the leg. I then manually positioned the servo horns to get as close to the 90 degrees as possible. When I had screwed the horns firmly to the nearest position, I adjusted the 3 joints via the software to fine tune the position. The position starts at 0 and can be offset from -127 to +127.

5 more times and all the legs were calibrated.


By pajp, shot with Digimax L85 at 2008-08-08

Heres Lex' on the stand during the calibration process.

[paulp]

Config screen. This is where you set the basic measurements of your bot.

Typing ? in the Config screen gives:


By pajp at 2008-08-08

Initially it looks daunting but many of the values are already preset and will not need changing.

They are all well documented in the user manual and I had no problem working out what had to be entered and what could be left till later.

I entered the leg dimensions, body dimensions and basic angles and saved the values.

Leaving the config screen, i returned to the main menu and typed "WAKE". Lex stood up, just as I'd seen V4b, V5 and iCHex do so on the videos and on the T.V. It took me ten minutes to stop smiling and showing it to my lads...

From the main screen you can enter SIM CONTROL and you are given a list of simple commands that allow basic control of the bot


By pajp at 2008-08-08

So I got my video cam going and made this...

[youtube=XMkFZk353mg][/youtube]

Its a bit inactive but thats me trying to type the commands long-hand while recording. Not good..

The important thing here is that it took an hour and a half to fit, config and calibrate enough to get it walking.

[paulp]

Getting my Smirf running

I've had my BlueSmirf bluetooth for a year or more now and find it a very good device..


By pajp, shot with Digimax L85 at 2008-08-08

As the image shows, CN17 provides access to the Serial ports for either config or control. It also provides a convenient 5V and GND so 4 wires later and its connected and working.

Matts Demo application quickly connected to the Smirf and now I have access to translate and rotate functionality via bluetooth

[youtube=XuUermew2Rg][/youtube]

[youtube=Ir5rpyDnuoc][/youtube]

In both of these videos, the Logic and servos are only running on 4.5V. The servos can handle up to 10.8V but on this floor it just cannot get enough purchase. The bot would move faster but just slipped on the floor. Not a problem with p.Brain just a failing of my design.

Also this is a V5 sized bot. The visble floor area is about 8 foot square..

[Matt Denton]

Oops.. the last two videos you pasted don't seem to work? Otherwise.. all looking great!

[paulp]

It seems to take forever for YouTube to process videos

[jaspinall]

I'm like a kid at christmas here watching these vids, and checking up on the progress of LM Phoenix too

[paulp]

Okay Matt

2 things

Version number still shows 0.2 in 0.3 software (show stopper NOT)

Suggested Manual change... I am testing the different configs at present in particular ACA and PCA. They both work fine but it might be worth putting in the manual that ACA and PCA must be set before Calibrate..

Also FYI, I've started on PIP and so far can Wake and Sleep over PIP from VB.Net

[Matt Denton]

Version number still shows 0.2 in 0.3 software (show stopper NOT)

Yeah spotted that after I sent the file, bot to worry for now..

Suggested Manual change... I am testing the different configs at present in particular ACA and PCA. They both work fine but it might be worth putting in the manual that ACA and PCA must be set before Calibrate..

Yup, can look at that.

Also FYI, I've started on PIP and so far can Wake and Sleep over PIP from VB.Net

Great, I have a few more PIP commands to add yet, they already exist but I decided to add them once I had done further testing. One think I will do is add filtering to the 'A' auxiliary servo position command, this way the servos will move smother at slower refresh rates.

[paulp]

I've been working on PIP with .NET and managed to get a reasonable data stream going with Matts help..

The following video shows Lex and p.Brain doing translate and rotate over PIP. Im using VB.NET with XNA game studio so its controlled via my XBOX 360 controller.

[youtube=NjEeHlkYWEs][/youtube]

When its tidied up a bit I will post the code for us lesser mortals who don't use C or C++...

There are a few anomalies with .NET that can be overcome..