Mecanum Wheel Rover 2 (or 1.1)... mmm floating switching regulator looks funny

The parts list

A sample of the little bits and pieces

Assembly Instructions

1. For each wheel, attach the circular servo horn that comes with the servo with the hub using 4 M2x4 self tapping screws.  Take care to hold the servo horn tightly to the hub while screwing.
2. For each wheel, insert 7 bearings into the ‘flanges’ of the wheel.
   • Depending on your printer, this should be a tight fit.  If it doesn’t fit, gently file the inside of the hole or using a M6 drill bit to clear.  I recommend using the file to keep the tight fit.
3. Attach the rollers onto each wheel with a M3 bolt and nut combination.
   • Again depending on your printer, the bolts should fit through (maybe a bit tight).  If they don’t fit use a M3 drill bit to clear the roller holes.
4. Attach each assembled wheel onto the servo.  Remember to install the horn screw!
5. Calibrate the centre position of the servos using the small adjustment pot at the rear of the servo.
   • Send a centre 1.5ms signal to each servo and adjust the pot until the servo doesn’t move.
6. Attach each servo onto a frame using the mounting screws that come with the servo.  Note the orientation of the wheels!  An extract out of MWRover.js shows not only my horrible ASCII art skills but how you should attach the wheels.

MWRover Axes
         F
       _____
   [\]|2   1|[/]
L     |     |      R
   [/]|3___0|[\]

         B

1. Connect each servo to the USB Servo controller as per the numbering above.  e.g. Wheel ’1′ goes to channel 1.
2. Mount the battery holder frame and chumby holder frame to the servo frame using M2x8 self tapping screws.
   • Note : The servo frame has numerous mounting points for you to mount to, and you could mount other components if you wish.  Use a 1.6mm diameter hole, and an optional 4mm diameter x 2mm deep recess for the mating component.
3. Connect the electronics and load the software! [Hope you can figure it out, if not ask away!]
   • Its slightly different depending on the electronics you use.  For the C1 I connected a second USB Connector on the empty footprint, for the Infocast you see above I soldered a Mini-USB cable directly to the breakouts, for the Chumby Hacker Board I suspect you can do the same.  WiFi Dongle pointing up for max range!

Software

Full source code is available for download from :-

http://code.google.com/p/madox/source/browse/#svn%2Ftrunk%2FMWRover

Android accelerometer/magnetometer control might be coming soon…

Edit : Typed this up for someone else so might as well paste it here :-

• Copy the MWRover directory onto the /mnt/storage partition of the Chumby/Infocast.  If copying directly to the SD card, this is probably the largest partition on the card.
• Power on the Chumby/Infocast, and run the shell script install.sh.  You can run the command via serial terminal or SSH.  Power cycle the Chumby/Infocast.
• Once it boots up, it should start up a WiFi access point called MWRover.  Connect to it using your Android Phone or even your PC.
• Once you’re connected, open your browser and point it to http://10.10.10.10:8080/MWRover.html [Sorry about this long address...forgot to make it something sensible... so bookmark it if you need].
• You should get a page where there’s a blue top bar, and a blue bottom bar.
  • Touch and drag anywhere in the middle black area moves the rover.  Let go to stop the movement.
  • Touch and drag in the top blue bar left/right to rotate the rover.
• No software install required on Android/PC/iPhone, its all browser based.

Videos

Test video of the new Rover…first 135 seconds is me figuring out what was wrong…

Video of the first rover…software is the same except a ‘-’ sign moved

]]> http://www.madox.net/blog/2011/01/24/mecanum-wheel-rover-2/feed/ 40 http://www.madox.net/blog/2011/01/09/ti-ez430-chronos-watch-python-library-remote-control/ http://www.madox.net/blog/2011/01/09/ti-ez430-chronos-watch-python-library-remote-control/#comments Sun, 09 Jan 2011 11:18:38 +0000 Madox http://www.madox.net/blog/?p=779 Around one year ago I ordered some of those supposedly wonderful TI eZ430 “Hackable” Watches but only received them last October since I had to wait for the 433Mhz version.  Three months later I finally decided to have a go at trying it out and wrote a Python library for in the process.

Silly video first…

It is quite a neat little watch for $50, the default factory firmware has enough features on it for most purposes that you wouldn’t need to touch it to use it in a typical application.  I know someone who is using it as a watch…

There’s enough information floating on the Internet about this already, with very useful information on the TI Wiki.  Annoyingly though, most of the information floating around is in bits and pieces and in some cases plain wrong.  I ended up writing a quick Python library and was pleasantly surprised at how easy it was to access most of the watch functions, the main ones of being able to read the accelerometer and button press data.

With a Python library in hand, I tried using it to remote control the Mecanum Wheel Rover.  And as seen in the video above, not very impressive results and the problem wasn’t in my code.

I’m not sure if it is the 433Mhz version and the fact that there isn’t enough space for a decent antenna, but the range was horrendous.  I would lose complete control of the rover at around 2.5 metres and anything over 1.5 metres was hit and miss.  Considering the average human height, the Chronos (or at least my 433Mhz one) is pretty must useless for direct remote control purposes.  Using it as a wireless door lock mechanism?  That’s probably a good use for it  Any other ideas what I can use this watch for?

Back to WiFi/RFM12Bs and nRF24L01+s for remote control!

If anyone is interested, here is a slightly messy Python library for interfacing to it :-
TIChronos.py_2010-01-09

I’ll tidy it up later when I have time or when I come up with a use for the watch

The ‘quick and nasty’ software files are still the same as in the previous post.  Pure software test only, couldn’t resist the temptation to try it via WiFi on a stock Chumby instead of USB tethering.  As such the hardware frame is a bit too flimsy and the batteries aren’t enough to power the Chumby without brown-out resets.  These will be improved upon soon

This demonstrates the ‘touch’ (initialize) and ‘swipe’ (move/offset) control on touch screens.  Will try the DeviceMotion Javascript API on iOS 4.2 devices (iPhone 4G/iPad) if I can get my hands on that filth…

Video!

Previous Posts :-

• http://www.madox.net/blog/2010/12/19/mecanum-wheel-base/
• http://www.madox.net/blog/2010/12/24/mecanum-wheel-base-software-test/

I didn’t want to fiddle around with getting power to the Chumby, so the test is simply using my trusty old laptop and the EasySync adapter.  Only the speedometer, the tachometer and the accelerator pedal position is attached because again I’m too lazy to fiddle with my cable layout and as such its connected to the Mazda HS-Can bus only rather than the MS-Can where the goodie trip computer information is contained.

Almost every concoction of technology is used ranging from CAN, USB, PHP, HTTP, Shared Memory, XML, Flash, to an obscure programming language called HaXe.  Here is the result :-

The flash movie was set to 6 frames per second and the responsiveness of the data was superb.  I think I’ve stated before that the CAN speed data differs to the one displayed on the instrumentation cluster and this again really shows at higher speeds.

All I need to do now is to try it on a Chumby, there should be no portability issues as I’ve tested both flash and php on the Chumby before.

So does anyone have any comments and suggestions on the GUI and what else I could put on it?

Picture time :-

Most of the gear laid out on carpet

Read on for a little bit more…

All crammed into a waterproof case for a test fit

Motor/pump mounts attached by cable ties...

Motor/pump mounts attached by cable ties...

Water Float Test

Water Float Test

Parts List so far

• Asus WL-520GU Wireless Router
• Denkovi USB 8 Channel Relay Board
• AV-Tech AVI202 IP Camera
• Johnson L450 Cartridge Bilge Pump
• 12V 7Ah SLA Battery
• 6V 3.2Ah SLA Battery
• $8AUD Waterproof Case from the discount store

Video time :-

Johnson L450 Bilge Pump Thrust Test

Why do I need a toolchain for programming ARMs?

1. I found a LPC2378-STK development board in my room
2. I want to give ARM programming a try (PS WinAVR is great for programming AVRs)
3. I found I have some spare ARM7 LPC2378′s lying around (WTF?) and thought I’ll actually complete my Chumby Speedometer on my car project!

The compile process should be pretty straight forward, but I made a few stuffup’s along the way.

• I had originally wanted to keep it neat and install to a new directory, then the PATH annoyance thing hit me.  Setting the path under my user shell didn’t carry over when using sudo which is required to make install.  Solved using sudo -s, but then in the end i just redid it all and installed to /usr/local/.
• Realised (should have known) that you need ‘GMP’ and ‘MPFR’ to compile GCC.  Available as packages libgmp3-dev and libmpfr-dev in Ubuntu.
• Did my usual of forgetting to set up the prefix install location when configuring…minor boo boo

Setting it all up

Install any packages you need… build-essential is probably essential… GMP and MPFR could be got by using

sudo apt-get install libgmp3-dev libmpfr-dev

Set-up some directories…I opted to use create an ‘arm-elf’ directory in my home to hold both the source and build directories…

cd ~
mkdir arm-elf arm-elf/src
cd ~/arm-elf/src

Get the latest sources…

Get the latest sources for binutils, gcc, newlib, insight (click the links if you need).  The versions I used should be obvious from the filenames below.  Just be wary that the insight front page is not kept up to date but you’ll find the latest if you follow any of the release links anyway.

wget http://ftp.gnu.org/gnu/binutils/binutils-2.19.tar.bz2
wget http://gcc.releasenotes.org/releases/gcc-4.3.2/gcc-4.3.2.tar.bz2
wget ftp://sources.redhat.com/pub/newlib/newlib-1.16.0.tar.gz
wget ftp://sourceware.org/pub/insight/releases/insight-6.8.tar.bz2

Unpack the sources…

tar -xvjf binutils-2.19.tar.bz2
tar -xvjf gcc-4.3.2.tar.bz2
tar -xvzf newlib-1.16.0.tar.gz
tar -xvjf insight-6.8.tar.bz2

Tweak the gcc source config…

Make a minor config tweak to the gcc source.  Edit gcc-4.3.2/gcc/config/arm/t-arm-elf and append mno-thumb-interwork/mthumb-interwork after MULTILIB_OPTIONS and normal interwork after MULTILIB_DIRNAMES.  I used nano, see the screenshot below if I haven’t been too clear

nano ~/arm-elf/src/gcc-4.3.2/gcc/config/arm/t-arm-elf

Start building with fingers crossed…

Now we can start building the toolchain.  Note my prefix is /usr/local.  First off binutils!

cd ~/arm-elf/
mkdir build build/binutils-2.19 build/insight-6.8 build/gcc-4.3.2 build/newlib-1.16.0

cd ~/arm-elf/build/binutils-2.19
~/arm-elf/src/binutils-2.19/configure –target=arm-elf –prefix=/usr/local –enable-interwork –enable-multilib –with-float=soft –disable-werror
sudo make all install

Next just the gcc part of gcc…note we configure the newlib src headers here…

cd ~/arm-elf/build/gcc-4.3.2
~/arm-elf/src/gcc-4.3.2/configure –target=arm-elf –prefix=/usr/local –enable-interwork –enable-multilib –with-float=soft –disable-werror –enable-languages=”c,c++” –with-newlib  –with-headers=~/arm-elf/src/newlib-1.16.0/newlib/libc/include
sudo make all-gcc install-gcc

Now newlib…

cd ~/arm-elf/build/newlib-1.16.0
~/arm-elf/src/newlib-1.16.0/configure –target=arm-elf –prefix=/usr/local –enable-interwork –enable-multilib –with-float=soft –disable-werror
sudo make all install

Coming back for the rest off gcc (needed newlib)

cd ~/arm-elf/build/gcc-4.3.2
sudo make all install

…and finally insight gdb

cd ~/arm-elf/build/insight-6.8
~/arm-elf/src/insight-6.8/configure –target=arm-elf –prefix=/usr/local –enable-interwork –enable-multilib –with-float=soft –disable-werror
sudo make all install

Voila done!  I should now have all my arm-elf tools!  Just a check…

madox@madox-laptop:/usr/local/bin$ ls arm*
arm-elf-addr2line  arm-elf-gcc        arm-elf-insight  arm-elf-run
arm-elf-ar         arm-elf-gcc-4.3.2  arm-elf-ld       arm-elf-size
arm-elf-as         arm-elf-gccbug     arm-elf-nm       arm-elf-strings
arm-elf-c++        arm-elf-gcov       arm-elf-objcopy  arm-elf-strip
arm-elf-c++filt    arm-elf-gdb        arm-elf-objdump
arm-elf-cpp        arm-elf-gdbtui     arm-elf-ranlib
arm-elf-g++        arm-elf-gprof      arm-elf-readelf

Yup all there and runs   Now the search for the LPC header files… argh

PS : If you copy and paste my commands, be wary of line breaks… I didn’t put \’s anywhere…