Features, applications, and real use cases
Learn where direct drive motors are used, and see how our high-torque, hollow-shaft, world’s smallest-class direct drive motors help achieve space saving and high precision

What Is a DD Motor?

A DD motor, or direct drive motor, is a motor that drives the load directly without using a gearbox or belt.
Because the mechanism is simple, there is no backlash or wear caused by transmission components, which helps achieve quiet operation, long service life, and highly accurate positioning.
A key feature is its ability to generate high torque at low speed, making it widely used in fields that require precision and reliability, such as industrial robots, inspection equipment, and medical devices. Our μDD motors deliver high torque in a world’s smallest-class size, contributing significantly to space saving and lighter equipment design.

What Is Gearless Drive?

This is a drive method in which the motor rotates the load directly without using a gearbox or gears.
Because there is no gear wear or backlash, it enables highly accurate positioning and smooth motion.
Since fewer components are required, the entire machine can be made smaller and lighter, while also improving quietness and service life.
It also offers advantages such as lower maintenance cost and improved safety, making it an ideal structure for precision equipment and robotic motion.

What Is Backdrivability?

Backdrivability refers to the ability of a motor output shaft to rotate smoothly in reverse when external force is applied.
In general motors that use gears or reducers, the shaft is difficult to move when external force is applied, which makes flexible motion difficult.
In contrast, motors with excellent backdrivability respond naturally to external force, giving a smooth feel almost like moving something by hand.

What Problems Can DD Motors Solve?

• High-precision positioning

  Because no gears are used, there is no play or backlash, making micron-level positioning possible.

• Smaller and lighter equipment

  Because no gearbox or belt is required, the entire machine can be designed in a more compact form.

• Quiet and smooth operation

  Because there is less mechanical friction, DD motors offer excellent quietness and smooth motion.

• Lower maintenance cost

  Because there are fewer wear parts and long service life, maintenance effort and cost can be reduced.

• Safe human collaboration

  Because of high backdrivability, the system can operate more safely even when interacting with people.

• Cleaner cable and tube routing

  The hollow-shaft structure allows cables and tubing to pass through the motor, simplifying machine design.

Main Benefits of Going Gearless

• Quieter operation

  Because there is no gear sliding noise, the working environment improves and abnormal machine sounds are easier to notice.

• Higher precision

  Because the system is gearless, there is no backlash, which improves the accuracy of the drive section.

• More compact design

  Fewer parts help reduce machine size and save installation space.

• Better acceleration

  Because there is less inertia and less mechanical loss, torque can be used more efficiently for acceleration and deceleration.

• Backdrivability

  This characteristic is advantageous for haptic feedback in master-slave control.

Learn more about master-slave control ➡︎

Introducing the World’s Smallest-Class Direct Drive Motor
“μDD Motor”

Large Bore Series, Φ100 to Φ60

MDH-100 Series

A new φ100 size has joined the μDD Motor lineup. This is the highest-torque μDD motor in the series, with peak torque of 9.6 Nm.

MDH-70 Series

Compact motor with a large-diameter hollow shaft. Ideal for index tables. A strong alternative to rotary actuators, and well suited for robots, equivalent to elbow and shoulder axes.

MDH-60 Series

Compact motor with a large-diameter hollow shaft. Ideal for end effectors and robot joints.

Compact High-Torque Series, Φ40 to Φ30

MDH(12)-40 Series

Expanded inner-diameter version of the MDH-40 series. Cables, lasers, and other components can be routed through the φ12 mm bore.

MDS/MDH-40 Series

Ideal for end effectors, transfer θ axes, alignment applications, production equipment automation, and robot wrist-class joints.

MDS/MDH-30 Series

Ideal for high-precision dispensers and compact gimbal drives. Threads can be added inside the hollow shaft, and a rotary joint can be installed to pass an air tube through the center.

Ultra-Compact Series, Φ21 to Φ13

MDS/MDH-20 Series

World’s smallest-class through-shaft servo motor. Ideal for end effectors, including hands, grippers, and Zθ units. Also suitable for compact hands when combined with a low reduction-ratio gear.

MDS-13 Series

The world’s smallest direct drive motor. Ideal for grippers and robot hands handling lightweight workpieces such as electronic components.

The μDD motor, or micro direct drive motor, is a world’s smallest-class direct drive motor independently developed by Microtech Laboratory.

Unlike conventional motors, it uses a gearless drive structure that transmits motor rotation directly to the load without a reducer, eliminating backlash and wear while enabling smooth, highly accurate motion.

It is specially designed to deliver high torque in the low-speed range, making it suitable for applications that require precise positioning and reliability, such as semiconductor manufacturing equipment, inspection systems, and industrial robots.

In addition, the motor integrates a high-resolution encoder for accurate control down to very fine angular movement. Its hollow-shaft structure also allows cables and air tubes to pass through the center, helping reduce equipment size and improve design flexibility.

Combining compact size with high torque, high precision, and quiet operation, the μDD motor is an innovative solution for next-generation motion control where conventional drive systems cannot meet performance requirements.

μDD Motor Adoption and Customization Examples

Industries

Comparison of μDD Motors and Typical DD Motors, Sample

Support and Service System
for Reliable μDD Motor Use

● Selection Support

Once you contact us, a dedicated representative will support your motor selection.
For motor and driver selection, please click here

● After-Sales Service

Our hardware products are managed under a strict quality assurance system and have passed multiple tests.
In the unlikely event of an initial defect, we will replace the product free of charge.
Our after-sales service includes repair support and root-cause analysis for performance issues.

• Tuning support

　• Auto-tuning function
　Implementation procedure and actual performance data are available here
　Released in 2024

　• Further optimization with manual tuning
　Tuning recipes and procedures are available here (user registration required)
　To request paid tuning support by MTL engineers, click here

　• You can also use drivers that your team is already familiar with.
　Supported manufacturers are listed here

Frequently Asked Questions

Q　What type of motor is a μDD motor?
A　It is an AC servo motor. The driver power supply voltage is DC, but internally it uses a three-phase PM rotor. It enables smooth position and speed control from ultra-low speed to high speed, as well as highly accurate current control.

Q　Why can μDD motors achieve high-precision positioning?
A　MTL’s motor core uses finer slot division than typical motors from other manufacturers. In addition, the integrated encoder has high resolution and monitors position more finely, which enables highly accurate positioning.

Q　One of the features of equipment using μDD motors is quiet operation. Why is it quieter?
A　Because equipment built with a direct drive mechanism eliminates the mechanical friction noise caused by high motor speed and the sliding friction noise generated by reducers.

Q　Can it replace an existing motor?
A　In addition to torque, current, and speed control using MTL drivers, it can also be connected to Mitsubishi Electric MELSERVO-J5 and Panasonic MINAS series drivers. Please contact us for specific model selection.

Q　Is there a comparison table with conventional motors?
A　The comparison with conventional motor-plus-gear actuators is shown below.

About Microtech Laboratory