Dynamixel MX-64T Actuator

The Dynamixel servomotors

• All-around assembling structure: you can make robots of various forms as using different option frames.
• Powerful feedback : It can read current position of Dynamixel or speed as well as various information such as internal temperature, supply voltage, target position.
• Simple connection structure: Wiring is simple because it is linked by Daisy Chain.
• Alarm function: When internal temperature, torque, supply voltage etc. escaped appointed range, it gives feedback about that situation. Also in such emergency situation, it flash LED or be Torque off.
• Compliance configuration: It can configure the compliance to control the position.
• Torque set up : Torque can be set up by 1023 steps from maximum Torque to free run state.
• Low-electric current/high voltagedrive : Its efficiency is high because it runs by high voltage and it improves stability of robot system that is formed by Dynamixel because current consumption is low.
• Status LED : It has LED that can check state of the Dynamixel.
• Drive by network: Dynamixels have unique ID and are controlled by Packet communication on a bus. It supports network of TTL, RS 485, and CAN etc. according to model.

This video illustrates the capabilities and the existing application for Dynamixel servomotors:

Programming the Dynamixel servomotors

The servomotors have to be linked to a main controller (CM-900, CM-700, CM-5, CM-510, CM-530, or OpenCM9.04) to be commanded. The progams are made with RoboPlus, which allow really easy programmation, without much previous knowledge.

The most recent main controllers support embedded C and there is a SDK for you to developp your own applications.

The Dynamixel MX-64T servomotor

The MX-64R and MX-64T are new Dynamixel servomotors in the MX range. They replace and improve the RX-64 servomotor with a new absolute contactless encoder with 12 bit resolution (4096 positions), can be positionned over 360° in joint mode (251° previously), can be speed controlled in wheel mode and estimate their torque based on current.

Moreover they are controlled with a PID (proportional integral derivative), which parameters can be set servomotor by servomotor. Admissible values are between 0 and 255 and the PID coefficients are modified with the following formulas:

The case of the RX-64 has also been lightly modified, the MX-64T servomotor is therefore not compatible with the HN05-N101/T101 horn.

The Dynamixel servomotor MX-64T supports the TTL communication protocol (when MX-64T supports RS484 communication) with high speed (3Mbs), it is compatible with the CM-510, CM-530, CM-700 and OpenCM9.04 main controllers. Warning, the operating voltage is not the same as the RX-64 voltage.

Technical specifications of the Dynamixel MX-64T actuator

• MCU : ST CORTEX-M3 (ST32F103C8 @ 72MHZ,32BIT)
• Motor : Maxon
• Position sensor : Contactless absolute encoder (12BIT,360 DEGREE)
• Stall Torque : 5.5N.m (at 11.1V, 3.9A), 6.0N.m (at 12V, 4.1A), 7.3N.m (at 14.8V, 5.2A)
• No load speed : 58rpm (at 11.1V), 63rpm (at 12V), 78rpm (at 14.8V)
• Résolution : 0.088° x 4.096
• Running degree : 360°
• Control algorithm : PID
• Command :digital packet, baud rate : 8000 bps ~ 3 Mbps
• Protocol : Half duplex Asynchronous Serial Communication (8bit,1stop, No Parity)
• Link (physical) : TTL Level Multi Drop Bus
• Weight : 126g
• Voltage : 10 ~ 14.8V (Recommended voltage 12V)
• Gear ratio : 200 : 1
• ID : 254 ID (0~253)
• Feedback : Position, Temperature, Load, Input Voltage, Current, etc.
• Ide current : 100 mA
• Dimensions : 40.2mm x 61.1mm x 41mm (exact dimensions available here)
• Material : Full Metal Gear, Engineering Plastic Body

All the technical specifications of the Dynamixel MX-64R actuator are available on the website of the manufacturer at https://emanual.robotis.com/docs/en/dxl/mx/mx-64/

Comparing the various Dynamixel actuators

Comparison table between all Dynamixel servomotors robotis

The chart below compare the Dynamixel actuators on their performance. Servomotors are differentiated by communication type (and the MX range proposes both protocols).