Acknowledgement

Most of the source code and architecture used in this project was adapted from the PyDynamixel_v2 library made by the amazing members of TauraBots.

About this library

This library wraps the dynamixel_sdk to hide its complexity and attempts to expose its features in a more user-friendly manner.

It has three classes.

• DxlComm is responsible for opening and starting a communication port like USB.
• Servo is responsible for controlling dynamixel motors. You can use it for things such as getting the position of the servo, sending to to a goal position etc.
• ServoGroup is responsible for sending commands and receiving data from servos with the same control table and protocol simultaneously.

Installing

Simple install

The quickest and easiest way of installing this library is through pip. Run the command pip install dynamixel-py

Install from source

1. Clone this repository using git clone https://github.com/rohitthampy/dynamixel_py.git
2. Create a virtual environment and pip install dynamixel-sdk
3. Create your python project at the root of this repository.
4. Have a look at the examples for inspiration.

Usage Examples

Examples for controlling one motor at a time

• Getting position data from a servo

import time

from dynamixel_py import DxlComm, Servo

# Starting communication with U2D2 or similar device
serial = DxlComm(port="/dev/ttyUSB0") # Eg: COM28 for windows

# Declaring a servo object
servo1 = Servo(servo_id=1, control_table="XL330")

# Disabling torque for a single servo
servo1.torque_enabled(is_enabled=False)

try:
    while True:
        print(servo1.get_position())
        time.sleep(0.1)

except KeyboardInterrupt:
    print("Stopping program")

• Setting the position of a servo

import time

from dynamixel_py import DxlComm, Servo

# Starting communication with U2D2 or similar device
serial = DxlComm(port="/dev/ttyUSB0") # Eg: COM28 for windows

# Declaring a servo object
servo1 = Servo(servo_id=1, control_table="XL330")

# Enabling torque for a single servo
servo1.torque_enabled(is_enabled=True)

count_1 = 0
servo1.set_position(count_1)
time.sleep(1)

while count_1 < 359:
    count_1 += 1
    servo1.set_position(count_1)

while count_1 > 0:
    count_1 -= 1
    servo1.set_position(count_1)

servo1.set_position(180)
time.sleep(1)

• Controlling motors of Protocol 1.0 and Protocol 2.0

import time

from dynamixel_py import DxlComm, Servo

# Starting communication with U2D2 or similar device
serial = DxlComm(port="/dev/ttyUSB0", baud_rate=1000000) # Eg: COM28 for windows

# Declaring servo objects
# By default, the baud rate for the XC330 is 57600, this was changed to 1000000 to work with the AX12
servo1 = Servo(servo_id=1, control_table="XC330") # Using the default protocol version which is 2

servo2 = Servo(servo_id=11, control_table="AX12", protocol_version=1)

# Enabling torque for both servos
servo1.torque_enabled(is_enabled=True)
servo2.torque_enabled(is_enabled=True)

count_1 = 0
servo1.set_position(count_1)
time.sleep(1)

while count_1 < 359:
    count_1 += 1
    servo1.set_position(count_1)
    servo2.set_position(count_1)

while count_1 > 0:
    count_1 -= 1
    servo1.set_position(count_1)
    servo2.set_position(count_1)

servo1.set_position(180)
servo2.set_position(180)
time.sleep(1)

Examples using sync read/write to control motor simultaneously

• Using sync read to read positions of multiple motors

from dynamixel_py import DxlComm, Servo, ServoGroup

serial = DxlComm(port="/dev/ttyUSB0")

servo1 = Servo(servo_id=1, control_table="XL330")
servo2 = Servo(servo_id=12, control_table="XL330")
servo3 = Servo(servo_id=15, control_table="XL330")

servo_group = ServoGroup()
servo_group.add_servos([servo1, servo2, servo3])

print(servo_group.get_total_servos())

servo_group.sync_torques_enabled(False)

try:
    while True:
        print(servo_group.sync_get_positions())

except KeyboardInterrupt:
    print("Stopping program")

• Using sync write to simultaneously control multiple servos

import time
from dynamixel_py import DxlComm, Servo, ServoGroup

serial = DxlComm(port="/dev/ttyUSB0")

servo1 = Servo(servo_id=1, control_table="XL330")
servo2 = Servo(servo_id=12, control_table="XL330")
servo3 = Servo(servo_id=15, control_table="XL330")

servo_group = ServoGroup()
servo_group.add_servos([servo1, servo2, servo3])

print(servo_group.get_total_servos())

servo_group.sync_torques_enabled(True)

servo_group.sync_set_positions([30, 45, 90])
time.sleep(1)


servo_group.remove_servos([servo1, servo2, servo3])
print(servo_group.get_total_servos())

• Using sync read and write together

import time
import random
from dynamixel_py import DxlComm, Servo, ServoGroup

serial = DxlComm(port="/dev/ttyUSB0")

servo1 = Servo(servo_id=1, control_table="XL330")
servo2 = Servo(servo_id=12, control_table="XL330")
servo3 = Servo(servo_id=15, control_table="XL330")

servo_group = ServoGroup()
servo_group.add_servos([servo1, servo2, servo3])

print(servo_group.get_total_servos())

servo_group.sync_torques_enabled(True)

print(servo_group.sync_get_positions())

servo_group.sync_set_positions([180, 180, 180])
time.sleep(0.5)

# Sends the servos to random positions between 0 and 350 degrees
for i in range(10):
    servo_group.sync_set_positions([random.randint(0, 350),
                                    random.randint(0, 350),
                                    random.randint(0, 350)])
    time.sleep(0.5)
    print(servo_group.sync_get_positions())

servo_group.sync_set_positions([180, 180, 180])
time.sleep(0.5)