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jeremiedecock / pyax12

Python library to control Dynamixel AX-12 actuators.
MIT License
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.. image:: https://readthedocs.org/projects/pyax-12/badge/?version=latest :target: https://readthedocs.org/projects/pyax-12/?badge=latest :alt: Documentation Status

========== PyAX-12_

Copyright (c) 2010,2015 Jeremie DECOCK (http://www.jdhp.org)

In collaboration with http://www.vorobotics.com

Description

PyAX-12 is an open source lightweight Python library to control Dynamixel AX-12+ actuators.

|Watch a demo on youtube|_

Note:

This project is still in beta stage, so the API is not finalized yet.

Dependencies

PyAX-12 is tested to work with Python 3.4 under Gnu/Linux (Debian 8), MacOSX (Mavericks 10.9) and Windows (7). Any Python 3.X version under recent Gnu/Linux, MaxOSX and Windows systems should suit too.

PyAX-12 can also be run on Raspberry Pi_ through the GPIO connector.

Python-serial_ is the only dependency required to install PyAX-12.

Note:

If you use ``pip`` to install PyAX-12, Python-serial will be automatically
downloaded and installed (see the following install_ section).

.. _install:

Installation

Gnu/Linux

You can install, upgrade, uninstall PyAX-12 with these commands (in a terminal)::

pip install --pre pyax12
pip install --upgrade pyax12
pip uninstall pyax12

Or, if you have downloaded the PyAX-12 source code::

python3 setup.py install

.. There's also a package for Debian/Ubuntu:: .. .. sudo apt-get install pyax12

Windows

.. Note: .. .. The following installation procedure has been tested to work with Python .. 3.4 under Windows 7. .. It should also work with recent Windows systems.

You can install, upgrade, uninstall PyAX-12 with these commands (in a command prompt_)::

py -m pip install --pre pyax12
py -m pip install --upgrade pyax12
py -m pip uninstall pyax12

Or, if you have downloaded the PyAX-12 source code::

py setup.py install

MacOSX

.. Note: .. .. The following installation procedure has been tested to work with Python .. 3.5 under MacOSX 10.9 (Mavericks). .. It should also work with recent MacOSX systems.

You can install, upgrade, uninstall PyAX-12 with these commands (in a terminal)::

pip install --pre pyax12
pip install --upgrade pyax12
pip uninstall pyax12

Or, if you have downloaded the PyAX-12 source code::

python3 setup.py install

Hardware setup

There are several ways to link AX-12 actuators to a computer. Three different configurations are described here.

For mor information, check the official AX-12 documentation <https://web.archive.org/web/20101008170532/http://support.robotis.com/en/product/dynamixel/ax_series/dxl_ax_actuator.htm>__ (archive).

Connecting AX-12 actuators to a computer (including Raspberry Pi computers) through USB port

The USB2Dynamixel_ can be used to connect AX-12 actuators to your computer. Actually, any FTDI serial/USB converter device should do the job.

For more information on USB2Dynamixel setup, check the official documentation <http://support.robotis.com/en/product/auxdevice/interface/usb2dxl_manual.htm>__.

Connecting AX-12 actuators to a Raspberry Pi through GPIO port

A small electronic circuit is needed to convert Raspberry Pi UART signals (on RX and TX pins) to the half-duplex ones required by Dynamixels (see this archive <https://web.archive.org/web/20100414173935/support.robotis.com/en/product/dynamixel/dxl_ax_main.htm>__).

The chips that converts full-duplex into half-duplex are either 74HC126/74HC04 or 74LS241.

Control Dynamixel AX-12 with the 74LS241 ''''''''''''''''''''''''''''''''''''''''

Here are the schematics of the electronic circuit required to control Dynamixel AX-12 with the 74LS241.

.. image:: https://github.com/jeremiedecock/pyax12/raw/master/docs/images/breadboard.png :alt: 74LS241 breadboard :align: center

.. image:: https://github.com/jeremiedecock/pyax12/raw/master/docs/images/schema.png :alt: 74LS241 schematic :align: center

Additional explanation can be found on the following pages:

A PCB by Thiago Hersan is freely available here:

For other schematics, check the following pages:

Control Dynamixel AX-12 with the 774HC126/74HC04 ''''''''''''''''''''''''''''''''''''''''''''''''

For the 74HC126/74HC04, check the following page:

UART configuration ''''''''''''''''''

Increasing the bandwidth up to 1Mbps may require a special setup (not tested yet):

Otherwise keeping the bandwidth to 57600bps should work out of the box (make sure you use the right Dynamixel ID and the Dynamixel bandwidth is properly setup to 56700bps).

Additional information ''''''''''''''''''''''

See also: https://github.com/jeremiedecock/raspberry-pi-python-snippets/tree/master/dynamixel_ax12

Documentation

.. PyAX-12 documentation is available on the following page: .. .. http://pyax-12.rtfd.org/

Example usage

.. Please check whether the serial port, the baud rate and the .. Dynamixel IDs defined in the following examples fits with your hardware.

In the following examples, the dynamixel_id, port and baudrate values should be adapted depending on your configuration:

If you use the USB2Dynamixel_ device, make sure its switch is set on "TTL".

Some other examples are available in the examples_ directory.

Ping a Dynamixel

This snippet prints True if the specified Dynamixel unit is connected and available at the given baudrate; otherwise it prints False.

::

from pyax12.connection import Connection

# Connect to the serial port
serial_connection = Connection(port="/dev/ttyUSB0", baudrate=57600)

dynamixel_id = 3

# Ping the third dynamixel unit
is_available = serial_connection.ping(dynamixel_id)

print(is_available)

# Close the serial connection
serial_connection.close()

Raspberry Pi users who connected AX-12 actuators to the GPIO connector should use the following code instead::

from pyax12.connection import Connection

# Connect to the serial port
serial_connection = Connection(port="/dev/ttyAMA0", rpi_gpio=True)

dynamixel_id = 3

# Ping the third dynamixel unit
is_available = serial_connection.ping(dynamixel_id)

print(is_available)

# Close the serial connection
serial_connection.close()

Scan (search available Dynamixel units)

This snippet prints the ID list of connected and available Dynamixel units (at the given baudrate).

::

from pyax12.connection import Connection

# Connect to the serial port
serial_connection = Connection(port="/dev/ttyUSB0", baudrate=57600)

# Ping the dynamixel unit(s)
ids_available = serial_connection.scan()

for dynamixel_id in ids_available:
    print(dynamixel_id)

# Close the serial connection
serial_connection.close()

Print the control table of the first Dynamixel unit

This snippet prints the control table of the specified Dynamixel unit (i.e. the internal state information of the Dynamixel unit).

::

from pyax12.connection import Connection

# Connect to the serial port
serial_connection = Connection(port="/dev/ttyUSB0", baudrate=57600)

dynamixel_id = 1

# Print the control table of the specified Dynamixel unit
serial_connection.pretty_print_control_table(dynamixel_id)

# Close the serial connection
serial_connection.close()

This snippet should print something like that::

model_number................. AX-12+
firmware_version............. 24
id........................... 1
baud_rate.................... 57142.9 bps
return_delay_time............ 500 µs
cw_angle_limit............... -150.0° (0)
ccw_angle_limit.............. 150.0° (1023)
max_temperature.............. 70°C
min_voltage.................. 6.0V
max_voltage.................. 14.0V
max_torque................... 1023
status_return_level.......... 2 (respond to all instructions)
input_voltage_alarm_led...... off
angle_limit_alarm_led........ off
overheating_alarm_led........ on
range_alarm_led.............. off
checksum_alarm_led........... off
overload_alarm_led........... on
instruction_alarm_led........ off
input_voltage_alarm_shutdown. off
angle_limit_alarm_shutdown... off
overheating_alarm_shutdown... on
range_alarm_shutdown......... off
checksum_alarm_shutdown...... off
overload_alarm_shutdown...... on
instruction_alarm_shutdown... off
down_calibration............. 46
up_calibration............... 972
torque_enabled............... yes
led.......................... off
cw_compliance_margin......... 0.3° (1)
ccw_compliance_margin........ 0.3° (1)
cw_compliance_slope.......... 9.4° (32)
ccw_compliance_slope......... 9.4° (32)
goal_position................ -0.1° (511)
moving_speed................. 512
torque_limit................. 1023
present_position............. -0.1° (511)
present_speed................ 0
present_load................. 0
present_voltage.............. 12.1V
present_temperature.......... 43°C
registred_instruction........ no
moving....................... no
locked....................... no
punch........................ 32

Move the first Dynamixel unit to various position angles

This snippet moves the first Dynamixel unit to 0°, then -45°, -90°, -135°, -150° (the maximum CW angle), +150° (the maximum CCW angle), +135°, +90°, +45° and finally goes back to 0°.

::

from pyax12.connection import Connection
import time

# Connect to the serial port
serial_connection = Connection(port="/dev/ttyUSB0", baudrate=57600)

dynamixel_id = 1

# Go to 0°
serial_connection.goto(dynamixel_id, 0, speed=512, degrees=True)
time.sleep(1)    # Wait 1 second

# Go to -45° (45° CW)
serial_connection.goto(dynamixel_id, -45, speed=512, degrees=True)
time.sleep(1)    # Wait 1 second

# Go to -90° (90° CW)
serial_connection.goto(dynamixel_id, -90, speed=512, degrees=True)
time.sleep(1)    # Wait 1 second

# Go to -135° (135° CW)
serial_connection.goto(dynamixel_id, -135, speed=512, degrees=True)
time.sleep(1)    # Wait 1 second

# Go to -150° (150° CW)
serial_connection.goto(dynamixel_id, -150, speed=512, degrees=True)
time.sleep(1)    # Wait 1 second

# Go to +150° (150° CCW)
serial_connection.goto(dynamixel_id, 150, speed=512, degrees=True)
time.sleep(2)    # Wait 2 seconds

# Go to +135° (135° CCW)
serial_connection.goto(dynamixel_id, 135, speed=512, degrees=True)
time.sleep(1)    # Wait 1 second

# Go to +90° (90° CCW)
serial_connection.goto(dynamixel_id, 90, speed=512, degrees=True)
time.sleep(1)    # Wait 1 second

# Go to +45° (45° CCW)
serial_connection.goto(dynamixel_id, 45, speed=512, degrees=True)
time.sleep(1)    # Wait 1 second

# Go back to 0°
serial_connection.goto(dynamixel_id, 0, speed=512, degrees=True)

# Close the serial connection
serial_connection.close()

Bug reports

To search for bugs or report them, please use the PyAX-12 Bug Tracker at:

https://github.com/jeremiedecock/pyax12/issues

.. _related-libraries:

Related libraries

Other libraries to control Dynamixel AX-12+_ actuators are referenced in the following (non comprehensive) list:

License

The PyAX-12 library is provided under the terms and conditions of the MIT License_.

.. _MIT License: http://opensource.org/licenses/MIT

.. _PyAX-12: http://www.jdhp.org/projects_en.html#pyax12 .. _Dynamixel AX-12+: http://en.robotis.com/index/product.php?cate_code=10101111&bbs_no=6#product_title .. _examples: https://github.com/jeremiedecock/pyax12/tree/master/examples .. _USB2Dynamixel: http://support.robotis.com/en/product/auxdevice/interface/usb2dxl_manual.htm .. _Python-serial: https://github.com/pyserial/pyserial .. _command prompt: https://en.wikipedia.org/wiki/Cmd.exe .. _device manager: http://windows.microsoft.com/en-us/windows/open-device-manager .. _Raspberry Pi: https://www.raspberrypi.org/

.. _PyPot: https://github.com/poppy-project/pypot .. _Pydyn: https://github.com/humm/pydyn .. _PyDynamixel: https://github.com/richard-clark/PyDynamixel .. _Dynamixel : https://pypi.python.org/pypi/dynamixel/1.0.1 .. _dynamixel_hr : https://github.com/HumaRobotics/dynamixel_hr .. _python_dynamixels : https://github.com/jes1510/python_dynamixels .. _ax12 : https://github.com/thiagohersan/memememe/tree/master/Python/ax12 .. _Dynamixel Monitor : http://robosavvy.com/forum/viewtopic.php?p=42991 .. _DynamixelMonitor : https://github.com/slavikshen/DynamixelMonitor

.. |Watch a demo on youtube| image:: http://download.tuxfamily.org/jdhp/image/pyax12_demo_youtube.jpeg .. _Watch a demo on youtube: http://youtu.be/5r0mNPhpf04