Question 1

What is a harmonic drive robot actuator and how does it work?

Accepted Answer

A harmonic drive robot actuator is an integrated joint module that combines a harmonic (strain wave) gear reducer, brushless torque motor, encoder, driver, and optional brake into a single compact unit. The harmonic gear works by using an elliptical wave generator to flex a thin-walled metal cup (flexspline) against a rigid outer ring (circular spline). Because the flexspline has two fewer teeth than the circular spline, each full rotation of the wave generator produces a small relative movement between the two — delivering high reduction ratios (typically 50:1 to 160:1) in a single stage with near-zero backlash. This makes harmonic drive actuators well suited for robot joints that require precise position control and high torque in a compact form factor.

Question 2

Harmonic drive actuator vs planetary gear actuator — which one should I choose for my robot?

Accepted Answer

It depends on the joint requirements. Harmonic drive actuators offer near-zero backlash (typically ≤15 arcsec), high positioning accuracy, and a compact single-stage design — ideal for joints that need precision, such as shoulders, elbows, and wrists. Planetary gear actuators provide higher torque density and longer service life under heavy loads, but with higher backlash (typically ≥12 arcmin) — better suited for high-load joints like hips and knees. Many humanoid robots use both: harmonic actuators for upper-body precision joints and planetary actuators for lower-body power joints. EYOU Robotics offers both the PHU Enhanced Harmonic series and the RP/PP Planetary series to cover full-body joint requirements.

Question 3

What communication protocols do EYOU PHU series actuators support?

Accepted Answer

The EYOU PHU Enhanced series supports EtherCAT and CANopen communication protocols. EtherCAT provides real-time, high-speed, synchronized multi-axis control — commonly required by professional motion controllers and industrial automation systems. CANopen offers flexible, cost-effective bus communication suitable for multi-joint daisy-chain setups. Protocol switching between CANopen and CAN custom is also supported by contacting the manufacturer.

Question 4

What sizes and torque ranges are available in the PHU Enhanced series?

Accepted Answer

The PHU Enhanced series covers 10 standard models with outer diameters from 40mm (PHU08L) to 170mm (PHU40H). Reduction ratios range from 51:1 to 161:1. Rated torque at 2000rpm spans from 1.25 N.m to 363 N.m, with peak torque up to 1,458 N.m on the largest model. All models operate at 24–48V DC. Weight ranges from 196g (PHU08L without brake) to 9,344g (PHU40H with brake). The hollow shaft inner diameter ranges from 4.4mm to 13mm for internal cable routing.

Question 5

Can harmonic drive actuators be used in applications other than humanoid robots?

Accepted Answer

Yes. While humanoid robots are a major application, harmonic drive actuators are used wherever precise rotary motion and compact size are needed. Common applications include collaborative robot arms (cobots), gimbals and stabilized platforms, medical devices, CNC rotary tables, AGV steering mechanisms, and semiconductor equipment. The EYOU PHU series is designed for humanoid robots, collaborative arms, and industrial automation.

Question 6

What is the lifespan of a harmonic drive actuator and what affects it?

Accepted Answer

The EYOU PHU series has a rated service life exceeding 8,000 hours under standard operating conditions (rated torque at 2,000 rpm). The primary wear component is the flexspline — a thin-walled steel cup that undergoes repeated elastic deformation. Factors that shorten lifespan include sustained operation above rated torque, high-speed impact loads, insufficient or improper lubrication, and operating outside the rated temperature range (-20°C to 60°C). Proper load planning and regular lubrication maintenance can significantly extend actuator life.

Question 7

Does the PHU series support force control?

Accepted Answer

The standard PHU series does not include a built-in torque sensor. For force control applications, EYOU offers the PHU-F series — a force-control variant that integrates a torque sensor directly into the harmonic reducer. The PHU-F provides torque accuracy of ≤0.5% FS, sensor resolution of 0.1% FS, and a sampling frequency of ≥5 kHz. Available models include PHU14H-70-F, PHU17H-80-F, PHU20H-90-F, and PHU25H-110-F. For applications that do not require a sensor, the standard PH series with KT calibration can achieve sensorless torque estimation accuracy within ±5%.

Question 8

What encoder configuration does the PHU series use and why does it matter?

Accepted Answer

The PHU series uses dual 19-bit absolute encoders — one on the motor side and one on the output side. This dual-encoder configuration provides two independent position references: the motor-side encoder tracks rotor position for FOC commutation, while the output-side encoder measures the actual joint angle after the harmonic reducer. This setup enables full closed-loop control, compensates for reducer compliance and backlash, and supports power-off position memory within single-turn range (±180°) — meaning the actuator knows its position immediately after power-on without a homing procedure.

工作电压	24-48V	编码器形式	双绝对值
工作噪音	<60dB	编码器精度	19bit
工作温度	-20~60℃	掉电抱闸	可选
使用寿命	>8000h	通信协议	EtherCAT/CANopen

PHU增强型谐波关节

产品概述

PHU增强型谐波一体化关节-型号与规格

PHU08L-40

PHU11H-52

PHU11L-52

PHU11H-60

PHU14H-70

PHU17H-80

PHU20H-90

PHU25H-110

PHU32H-142

PHU40H-170

PHU-F力控增强型谐波一体化关节-型号与规格

PHU14H-70-F

PHU17H-80-F

PHU20H-90-F

PHU25H-110-F

产品特点

分体式设计

模块化配置

双协议通信