This is an old one, but is working quite nice and should be still useful for working with Dynamixel motor (AX-12+, AX-12A).
The goal was to have a nice toolbox used for direct control of Dynamixel motors using USB2Dynamixel or any other USB-Serial (half-duplex, ~1Mbps) adapter.
Source code and short description:
https://github.com/adamlukomski/BioloidMatlab
Steps to get it working:
clone the repository
git clone https://github.com/adamlukomski/BioloidMatlab
Copy the whole directory +hw to your current Matlab directory. Matlab recognises
all the directories that are written as +dir as structures with functions inside,
so you can use dir.function() at the Matlab console.
First choose serial port number – 0,1,2,… for linux /dev/ttyUSB0, 1, etc., for Windows
5,6,7,8 for COM5, COM6, … ans so on.
hw.start( 0 )
This initialises the serial COM port for the USB2Dynamixel, now if you have a motor (let’s say number 13)
you can move it to the zero position:
hw.set_position( 13, 0 )
function set_position works in radians, so the usual permitted range for standard AX-12 would
be -2.61…2.61 (the Murata SV-01 potentiometer has the range of about 300 degrees). To retrieve a current position:
hw.get_position( 13 )
and to switch off the internal PID control for a moment:
hw.set_off( 13 )
If you want to limit the speed of one of the motors you can use
hw.set_speed( 13, 0.1 )
which limits the max speed to 10% (parameter range 0=0%, 1=100%).
If you would like to switch between closed loop PID-controlled joint mode and open-loop (servo behaves like a wheel
then, but still can read the positions during movement! in other words: you control the PWM of the H-bridge on the DC motor controller)
hw.set_mode_joint( 13 ) hw.set_position( 13, 0 ) pause(0.3) hw.set_mode_wheel( 13 ) hw.set_speed( 13, -0.25 )
set_speed() now controls the PWM on the motor, remember that now you can move forward and backwards (-1.0 … 1.0 )
get_pose() and set_pose() reads the current pose of a humanoid robot, including a little offset for hips so they don’t
collide if you accidentally push zeros to all joints.
Possible errors:
Error using loadlibrary (line 419)
Building libdxl_thunk_glnxa64 failed. Compiler output is:
gcc -I"/usr/local/matlab2012a/extern/include" -D_GNU_SOURCE -fexceptions -fPIC -fno-omit-frame-pointer
-pthread -I"/home/anil/phd/ravia/iva" -I"/home/anil/phd/ravia/iva/+hw/GLNXA64" "libdxl_thunk_glnxa64.c" -o
"libdxl_thunk_glnxa64.so" -Wl,-E -shared
In file included from libdxl_thunk_glnxa64.c:18:0:
/usr/local/matlab2012a/extern/include/tmwtypes.h:819:9: error: unknown type name 'char16_t'
typedef char16_t CHAR16_T;
^
Error in hw.start (line 11)
loadlibrary(['+hw/' computer '/libdxl.so'],['+hw/' computer '/libdxl.h'])
that means your compiler options are a little bit off with the compiler itself.
I solved mine by adding to the CFLAGS:
-Dchar16_t=UINT16_T
for correct gcc options and to CXXFLAGS
-std=c++11
to g++ options. Remember which architecture you are on: 32-bit - glnx86 or 64-bit - glnxa64. The config file is located either in your Matlab directory (main one):
/usr/local/MATLAB/R2012a/bin/mexopts.sh
or if you already tried mex -setup you will have a local copy in
~/.matlab/R2012a/mexopts.sh
In general: mex -setup will show you where the file is while doing the configuration of the compiler.
Mods:
Before:
glnx86)
...
CFLAGS='-ansi -D_GNU_SOURCE'
...
CXXFLAGS='-ansi -D_GNU_SOURCE'
...
glxa64)
CFLAGS='-ansi -D_GNU_SOURCE'
...
CXXFLAGS='-ansi -D_GNU_SOURCE'
...
after:
glnx86)
...
CFLAGS='-ansi -D_GNU_SOURCE -Dchar16_t=UINT16_T'
...
CXXFLAGS='-ansi -D_GNU_SOURCE -std=c++11'
...
glxa64)
CFLAGS='-ansi -D_GNU_SOURCE -Dchar16_t=UINT16_T'
...
CXXFLAGS='-ansi -D_GNU_SOURCE -std=c++11'
...