Dynamixel MX-12W servo motor

The Dynamixel servo motors

Presentation of the Dynamixel range

Dynamixel servo motors are integrated actuators that include:

• A reducer
• A controller
• A driver

Dynamixel servo motors have a unique identifier and communicate via digital packets.

The main characteristics of the Dynamixel range are:

• High position control accuracy (1024 steps for the AX, RX, and EX models; 4096 for MX).
• Numerous feedback functions for the servo motor’s different physical variables (current position, speed, voltage, internal temperature, etc.).
• An alarm depending on the internal temperature, torque or supply voltage, which is set off when these values exceed defined limits. The Dynamixel servo motor provides feedback and can correct the situation automatically.
• " Compliance Driving ": Control the amount of elastic force in the position control.
• Torque establishment: The torque can be established in 1023 steps, from maximum torque to freewheeling.
• Low current/high voltage operation: High efficiency as it operates at a higher voltage. The performance of your robotic system is also improved by its low current consumption.
• A status LED is used as a visual display of the Dynamixel’s status.
• Easier mechanical assembly through numerous compatible mechanical components.
• Easy ‘daisy chain’ wiring

The following video demonstrates the existing capabilities and applications of Dynamixel servo motors:

The Dynamixel MX-12W servo motor

To make life simple, the Dynamixel servo motor range can be divided into 3 families (if we leave out the small Dynamixel XL-320 servo motor, which is separate) by classifying them according to their footprint, i.e. their size and hence the mounting frames you need to use. Within each family, the servo motors are interchangeable in terms of the size of the outer case. This short introduction will help you anderstand this new servo motor’s positioning. So the 3 families are:

• Small servo motors: AX-12A , AX-12W and AX-18A
• Medium servo motors: RX-24F , RX-28 and MX-28
• Large servo motors: RX-64 , MX-64 and MX-106

The MX-12W is a servo motor that falls in the first family, in other words that of the AX-12A. As you see, it’s the first servo motor in this family to bear the prefix M (which distinguishes the latest generation of Dynamixel servo motors, which are smarter). Before the arrival of the Dynamixel MX-12W servo motor, you had only two choices for replacing the AX-12A: the AX-18A for power or the AX-12W for speed. You can now choose the MX-12W for control and intelligence, and benefit for example from its PID control.

Technical specifications of the Dynamixel MX-12W servo motor

• Microcontroller: ST CORTEX-M3 (STM32F103C8 @ 72 MHz, 32 bit)
• Position sensor: Absolute contactless encoder (12 bit, 360°)
• Motor: Cored motor
• Baud rate: 8,000 bps – 4.5 Mbps
• Control algorithm: PID
• Resolution: 0.088°
• Movement range: 0° – 360° / continuous rotation
• Weight: 54.6 g
• Dimensions: 32 mm × 50 mm × 40 mm
• Reducer ratio: 32:1
• No-load speed: 470 rpm (@ 12 V)
• Operating temperature: -5 °C to +80 °C
• Voltage: 10.0–14.8 V (recommended voltage 12 V)
• Control: Digital packet
• Protocol: Half-duplex asynchronous series communication (8-bit, 1 stop, No Parity)
• Connection (physical): TTL Level Multi Drop (daisy chain type Connector)
• ID: 254 IDs (0–253)
• Feedback: Position, temperature, load, input voltage, current, etc.
• Material: Engineering plastic
• Standby current: 60 mA

The following image shows a diagram of the Dynamixel MX-12W servo motor with the dimensions in mm:

Video showing the Dynamixel MX-12W servo motor