Honpine

Harmonic Drive Precision Rotary Actuator Unit

The rotary actuator unit is a power unit specifically designed for precision machine tools, industrial automation, and semiconductor applications. It typically integrates an inner-rotor frameless torque motor with components such as a reducer and encoder to form a complete rotary actuator unit. The control unit (driver) usually adopts an external drive configuration to achieve high-precision motion control for connected equipment.


Harmonic Drive Servo Actuator offer flexible voltage compatibility, supporting both high-voltage AC220V and low-voltage DC48V power inputs. They are widely used in fields requiring high precision and compact spatial integration, such as:Precision machine tool rotary tables,High-accuracy medical devices,5-axis laser cutting systems,Semiconductor manufacturing equipment.
Based on technical design differences, rotary actuators are categorized into two main types:

Standard Harmonic Gear Rotary Actuators

The harmonic rotary actuator integrates a high-precision harmonic reducer, encoder, and frameless torque motor. It is compatible with mainstream external drives, ensuring stable performance and long-term accuracy retention. Based on the characteristics of HONPINE’s high-precision harmonic reducer and motor rigidity, it achieves zero backlash. Optional features include a multi-turn absolute encoder and an integrated electromagnetic brake.The 220V version is widely used in precision CNC machine tools, 3C equipment, precision laser processing, inspection equipment, printing equipment, medical devices, glass polishing equipment, and more. The 48V version is widely used in robotic arms, AGV vehicles, mobile camera gimbals, and similar applications.

Large Hollow Shaft Harmonic Drive Rotary Actuators

The HONPINE large hollow harmonic drive actuator is an upgraded version of the standard harmonic rotary actuator with an enlarged central bore, allowing more cables, air tubes, and other lines to pass through. Based on a high-torque frameless torque motor, it features extremely low torque ripple, excellent dynamic response, high torque, high precision, and high rigidity. It offers IP65 protection, with customizable IP67 for special applications.

It is commonly used in electronics and semiconductor equipment, precision CNC machine tools, 3C equipment, precision laser processing equipment, LED equipment, inspection systems, medical devices, robotics and specialized robotic arms, printing machinery, digital printing equipment, glass processing equipment, and precision measurement instruments.

High Precision CNC Semiconductor Machinery Rotary Actuators

The HONPINE backlash-eliminating planetary reducer rotary actuator is designed to meet machine-tool-grade precision standards. Under standardized high-end testing conditions, its bidirectional positioning accuracy and repeat positioning accuracy outperform conventional planetary gear systems, cycloidal reducers, and even some German backlash-free reducers.

Its positioning accuracy can reach up to 5 arc-seconds, with extremely high torsional rigidity. It features a built-in rotary table bearing, making it suitable for machine tool rotary tables, tilting heads, panel manufacturing equipment, and measurement systems that require high load capacity, high precision, and high rigidity. It is widely used in industrial robots, five-axis machine tools, high-end equipment, and consumer robotics applications.

Servo Driven Rotary Actuators

Harmonic Drive Rotary Actuator Principle

A harmonic rotary actuator is an AC servo rotary actuator that integrates a high-torque precision harmonic reducer, a frameless torque motor, an optional hollow-shaft multi-turn absolute optical encoder, an electromagnetic brake, and a servo drive into one compact unit.

harmonic servo rotary actuator

What is a Harmonic Drive Actuator？

A harmonic drive actuator is a device that converts electrical energy into mechanical energy to achieve rotational motion of mechanical parts. Its core technologies include a motor, a harmonic reducer, and sensors. As the core component of a rotary actuator, the motor is responsible for converting electrical energy into mechanical energy to achieve the rotation of the mechanical parts; the reducer reduces the motor speed and increases torque to meet the needs of various application scenarios; and the sensors monitor the actuator's position and speed to achieve closed-loop control. Rotary actuators are widely used in various joints and drive components of humanoid robots, such as the head, neck, waist, arms, and legs. By using rotary actuators, humanoid robots can perform various complex movements such as walking, bending, grasping, and manipulating. In addition, rotary actuators can also be used in other automated equipment and intelligent devices, such as machine tools, automated production lines, and drones.

Advantages of Harmonic Drive Servo Actuator

Integrated Design

Integrates a high-torque precision harmonic reducer, frameless torque motor, multi-turn absolute encoder (optional hollow optical design), and electromagnetic brake into a compact unit. Compared with the conventional “harmonic drive + servo motor” setup, harmonic rotary actuators offer clear advantages in compactness, assembly efficiency, and overall system reliability.

 

Ease of Use

Features an optional hollow shaft design for convenient routing of cables, air lines, or laser beams, improving system integration flexibility. The actuator adopts long-life lubrication, eliminating the need for grease replacement or regular maintenance during operation, significantly reducing maintenance costs.

harmonic gear actuator

High Performance

Delivers high tilting rigidity, high torque output, and strong load capacity with smooth and stable operation. Each motor is individually tested before delivery to ensure low vibration and low noise performance. Combined with the precision of the harmonic reducer and motor stiffness, it achieves true zero-backlash transmission.

Low Maintenance

Designed for easy installation and compatibility with standard servo drives, enabling plug-and-play integration. It maintains positioning accuracy for over 15,000 hours at rated torque, ensuring long-term stable operation while minimizing maintenance and downtime.

Application of Harmonic Drive Strain Wave Reducer Rotary Actuator

Harmonic Drive Rotary Actuator integrates a high-precision harmonic reducer, encoder, and frameless torque motor. Compatible with mainstream external drives, it ensures stable performance and long-term accuracy. The large hollow shaft simplifies cable routing. Its modular design enables easy, low-cost maintenance, even after the reducer's service life. Rated IP65 (IP67 optional), it is fully sealed, easy to install, and ready to use. The 220V version suits CNC machine tools, 3C equipment, laser processing, and medical devices, while the 48V model fits robotic joints, AGVs, and PTZ cameras.

 

 

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  • precision rotary actuator for machine tools
  • Semiconductor equipment with harmonic actuator
  • robot with harmonic drive actuator
  • automation machine with harmonic rotary actuator
  • five-axis machining equipment with harmonic servo motor
  • CNC milling machine with harmonic servo actuator

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precision rotary actuator for machine tools

Harmonic AC Servo Rotary Actuator - FAQ

Compared to the harmonic DC joint motor, the harmonic AC servo rotary actuator has higher repeatability and rigidity, making it an industrial-grade harmonic actuator.

Key Parameters of Harmonic Rotary Actuators

A harmonic rotary actuator typically integrates a permanent magnet brushless motor (BLDC/PMSM), harmonic drive reducer, sensors, bearings, and other key components into a compact unit. Its performance is primarily evaluated based on output capability, positioning accuracy, dynamic response, thermal management, and reliability.

 

1. Output Performance

Torque

Torque includes both rated torque (the continuous output torque under normal operating conditions) and peak torque (the maximum instantaneous torque available during short-term overload, acceleration, or startup). Harmonic drive actuators offer high torque density and are commonly used in medium- and small-payload applications, such as robotic arms with payloads below 20 kg.

Speed

Speed specifications include rated speed (the maximum continuous operating speed) and maximum allowable speed. The selected speed and torque should match the load inertia and dynamic performance requirements. In general, an inertia ratio of 5:1 to 10:1 is recommended for optimal control performance.

 

2. Accuracy and Precision

Positioning Accuracy and Repeatability

Positioning accuracy refers to the deviation between the commanded position and the actual position, often reaching arc-second-level precision. Repeatability measures the actuator's ability to return to the same position consistently. Thanks to the near-zero backlash characteristics of harmonic drives, repeatability is exceptionally high.

Backlash

Because harmonic drives transmit motion through the elastic deformation of the flexspline, they achieve near-zero backlash. This is essential for high-precision positioning and smooth trajectory control.

Torsional Stiffness

Torsional stiffness measures the actuator's resistance to angular deformation under applied torque (N·m/rad). Higher torsional stiffness minimizes angular displacement under load, ensuring greater positioning accuracy and stability during dynamic motion.

 

3. Dynamic Performance

Control Bandwidth

Control bandwidth indicates how quickly the actuator can respond to high-frequency control commands. A higher bandwidth enables faster dynamic response and is particularly important for applications such as humanoid robot joints that require rapid and precise motion.

Response Speed and Acceleration

The actuator's response speed and acceleration depend on the motor characteristics, gear reduction ratio, and system inertia. These parameters determine how accurately and quickly the actuator follows motion commands.

 

4. Size and Integration

Dimensions, Weight, and Power Density

Harmonic rotary actuators feature a compact structure, lightweight design, and high power density. Their highly integrated architecture combines the motor, harmonic reducer, and sensors into a single unit, making them ideal for space-constrained applications such as robotic forearms and wrists.

Mechanical Interfaces

Important mechanical specifications include mounting dimensions, hollow shaft diameter, center bore size, and output flange configuration. These interfaces must be compatible with the robot structure and payload mounting requirements.

 

5. Thermal Management and Service Life

Temperature Rise

Temperature rise during continuous operation or frequent acceleration and deceleration directly affects actuator performance, reliability, and service life. Effective thermal management and heat dissipation are therefore critical.

Service Life

The service life of a harmonic rotary actuator is influenced by factors such as flexspline fatigue, lubrication quality, and operating conditions. Lifetime is typically specified in operating hours and should meet the expected duty cycle of the target application.

 

6. Environmental Protection and Reliability

Protection Rating (IP Rating)

Ingress Protection (IP) ratings, such as IP67, indicate the actuator's resistance to dust and water. Higher protection levels improve reliability in demanding industrial environments.

Vibration and Noise (NVH)

Low vibration and low noise characteristics are essential for precision motion systems. Superior NVH performance contributes to smoother operation, higher positioning accuracy, and improved user experience.

 

Selection Considerations

When selecting a harmonic rotary actuator, engineers should evaluate these parameters according to the specific application, whether for industrial robots, humanoid robots, collaborative robots, or precision rotary tables. Factors such as payload, motion profile, operating environment, and control requirements should all be considered to achieve the optimal balance of performance, reliability, and cost.

 

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