High Precision Harmonic Drive Robot Joint Actuator Solution for Robotic Elbows

The robotic elbow joint is a critical motion joint that connects the upper arm and forearm. It is mainly responsible for arm flexion and extension, posture adjustment, and changes in the position of the end effector. In humanoid robots, collaborative robots, and robotic arms, the elbow joint must not only withstand the torque generated by the forearm and end-effector loads, but also achieve high-precision, fast, and stable motion within a limited installation space. Therefore, the structural dimensions, output torque, positioning accuracy, stiffness, backlash, and dynamic response of the elbow joint directly affect the robot arm's range of motion, control accuracy, and operating capability.

A harmonic drive robot joint actuator integrates key components such as a high-precision harmonic drive reducer, servo motor, high-resolution encoder, brake, and drive control system into a compact unit. It provides a high reduction ratio, high torque density, and compact structure within the limited space available in a robotic elbow, while also delivering low backlash, high positioning accuracy, high stiffness, and excellent repeatability.

For humanoid robots, collaborative robots, and high-precision robotic arms, this integrated design can reduce joint size and system integration complexity while simplifying cable routing and mechanical connections. This enables the elbow joint to maintain stable, fast, and controllable motion during frequent start-stop operations, posture adjustments, and precision movements.

This article introduces three HONPINE models for robotic elbow joint applications.

HPJM Series (40–52)

The HPJM-RE40-52-PRO-XX is a high-performance integrated joint module from the PRO Series. It features a compact 40 mm outer diameter and a 52 mm hollow cable-routing passage. The module is designed for collaborative robots, lightweight robotic arms, and precision automation equipment.

• Gear Ratio: 51:101

• Rated Torque: 4 N·m at 2,000 RPM

• Maximum Allowable Torque: 5.5 N·m under average load / 8.9 N·m peak

• Impact Torque: 8.3 N·m at 1/2 of rated torque

• Speed Performance:

• Rated Speed: 80 RPM

• Peak Speed: 118 RPM

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TCHL Series (11, 14)

The TCHL Series joint modules cover a broad specification range from miniature precision joints to higher-load industrial applications.

The TCHL-11 (φ52) is the smallest and lightest joint module in the series. Without the brake, it weighs only 0.37 kg, while delivering a rated torque of 3.6 N·m and a peak torque of 25 N·m with a 100:1 reduction ratio. It also features an 8 mm hollow cable-routing passage, making it suitable for extremely lightweight applications such as dexterous hands, miniature collaborative robots, and medical and research equipment.

The TCHL-32 (φ131) is a heavy-duty configuration in the series. With a 101:1 reduction ratio, it delivers up to 267 N·m of rated torque and 799 N·m of peak torque. It also provides a 210 N·m allowable overturning moment and a 22 mm large-diameter hollow shaft, making it suitable as a core drive for heavy-duty industrial robotic arms and large automated rotary platforms.

Although the two models differ significantly in size and torque capacity, both are based on the same highly integrated joint technology platform. They are equipped with 17-bit dual encoders, support EtherCAT and CAN FD communication, and provide IP54 protection, with IP65 available as an option. The operating temperature range is -20°C to 50°C. Torque sensors and brakes are also available according to application requirements.

This integrated technology platform enables high-precision and highly integrated joint drive solutions for different robotic load requirements.

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HAG / HAU Series (11, 14, 17)

The HAG Series harmonic joint motors includes three frame sizes: HAG-11, HAG-14, and HAG-17. All models are based on a 48 VDC power supply platform and offer three reduction ratio options: 51, 81, and 101.

The series is equipped with high-precision absolute BISS-C encoders, providing 22-bit single-turn and 22-bit multi-turn resolution. It also integrates a high-response torque sensor with an 8 kHz sampling frequency and supports an optional power-off brake.

The series provides positioning accuracy of ≤75 arcsec, which can be customized to ≤20 arcsec, with repeat positioning accuracy of ≤10 arcsec.

The HAG-11, as the compact model, provides a rated torque range of 4.6–7.3 N·m and a peak torque range of 11.4–18 N·m, while weighing only 0.51–0.55 kg.

The HAG-14 and HAG-17 have highly similar mechanical dimensions and core electrical parameters, while offering higher torque performance. Their rated torque ranges from 10.5 to 21 N·m, with peak torque ranging from 23 to 35 N·m. Their weight is 0.875–0.92 kg, and they can be equipped with brakes providing a holding torque of ≥0.65 N·m. The HAG-11 brake provides a holding torque of ≥0.2 N·m.

Together, these models provide highly integrated, high-stiffness, and high-precision joint drive solutions for collaborative robots, humanoid robots, and precision automation equipment with different load requirements.

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Contact HONPINE for Robotic Elbow Joint Actuator Solutions

HONPINE provides high-precision harmonic drive robot joint actuator solutions for robotic elbow joints and other robotic joint applications. Contact HONPINE to discuss your application requirements and select a suitable harmonic joint module for your robot.