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Dynamixel: efficient servos for all types of robotics applications

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Dynamixel servos are smart actuator systems developed to be used as connecting joints on a robot or mechanical structure.

They are designed to be modular and daisy chained on any robot or mechanical design, with the aim of producing powerful and flexible robotic movements.

Dynamixel servos are efficient actuators with a fully-integrated DC (direct current) motor + reduction gearhead + controller + driver + network, all in one servo module actuator. They are programmable, networkable, and the actuator’s status can be read and monitored by means of a data packet stream. They are known for their durability and quality, and are used worldwide in lots of complex robotics projects.

The ThorManG3 humanoid robot is built using Dynamixel servo motors
The ThorManG3 humanoid robot is built using Dynamixel servo motors

The Dynamixel range is so huge that it’s not always easy finding your way around. In this article, we’ll help you choose the right servo for your project.

What’s new at Dynamixel?

More refined large servos

The XL range has extended its family with the XL330, which comes in two versions:

  • XL330-M288-T
  • XL330-M077-T

The XL330-M288-T offers a rotational speed of 100 revolutions per minute and a stall torque of 0.52, while the XL330-M077-T is faster at 363 revolutions per minute but has a lower stall torque (0.22).

Its main advantage remains its size, because it’s the smallest servo in the range. Measuring just 20 x 34 x 26, it easily dethrones the XL-320 (24 x 36 x 27).

Robots at sea

The waterproof XW series rounds out this range of robotics servos. There are 2 versions, the XW540-T260-R and the XW540-T140-R, one is fast and the other powerful. They’re ideal for use in aquatic environments and in high-humidity laboratory conditions.

The Dynamixel XW servo motors are waterproof
The Dynamixel XW servo motors are waterproof

How do I choose the right servo?

Here we look at a concrete use case with the Poppy humanoid robot, which is built using 3 different servo motors:

  • Dynamixel MX-28AT servo
  • Dynamixel MX-64AT servo
  • Dynamixel AX-12A servo

The Dynamixel AX-12A servo motor is the smallest in the AX series. It’s very effective for little actions involving not much weight. It’s used on the Poppy robot for wrist mobility.

The 2 other servo motors are from the MX range and are more powerful. MX-64AT servos are used for the pelvis and at the base of the legs. They allow the robot’s heaviest parts to move. MX-28AT servos have been chosen for the rest of the robot for mobility (medium weight, medium power).

Poppy humanoid robot
Poppy humanoid robot

Which series should I choose?

There are 7 different series of Dynamixel servos: AX, MX, XC, XH, XL, XM and XW.

You must take several criteria into consideration when choosing your servos:

  • Operating voltage
  • Stall torque
  • Stall torque
  • Stall torque
  • Etc.

XW series

The servos in the XW series can be easily isolated. They are waterproof. It’s their most important feature. They can be used for mechanical engineering, in laboratories and in wet environments.

AX series

The AX series works with an input voltage of 9 to 12V. AX servos are the brand’s entry-level servos and they use the TTL protocol.

We recommend them for your robots’ non-essential mechanical functions. They’re ideal for learning robotics, light prototyping and wheel motorisation. The manufacturer Trossen Robotics uses them in robot arms for example.

MX series

The MX series is the next level up from the AX series. It offers more advanced features, such as more precise position control, PID correction (less backlash), 360° position control and fast communication, making them particularly powerful components.

They are more powerful and robust and offer better control of fast and precise movements.

XL series

The XL series is the family of small servo motors. They’re used a lot in the field of education and for small prototyping.

XM and XH series

The XM and XH series offer significant advantages in terms of torque, speed, position and even PWM control!

The XH series is of a slightly higher quality (Maxon motor). They have a lower maximum speed and torque than the XM servos, but are more durable and energy efficient.

Dynamixel, the professional choice

The Korean brand ROBOTIS, the brains behind the Dynamixel range, also offers a Dynamixel-P series of more reliable, more robust servos offering position, speed and torque control.

These Dynamixel-P servos can be programmed in many languages, including C#, Java, Python, LabVIEW and MATLAB.