Harmonic actuator
MGU harmonic actuator
Compact robot-joint harmonic actuator with built-in EtherCAT/CANopen drive, dual 20-bit encoders and optional torque sensor, from 0.35 kg; aimed at humanoids and cobots.
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Pricing and availability
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Need Motion Control Products parts, a replacement or a suitable alternative? Send us a part number, or tell us what the machine needs to do. Our UK engineers will come back with the right product, pricing, lead time and delivery, whether that is the original part, a checked alternative or a complete axis.
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Spec builder
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Select every part you need and answer the questions an applications engineer would ask. Our engineers use your specification to come back with the right products, pricing and lead times. You see your summary before we ask for any details.
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- 2Performance
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What are you specifying?
Select everything you need. A motor, drive and gearbox can be specified together as one axis.
Key specifications
| Bore | 6.5–23 mm |
|---|---|
| Ingress protection | IP20 |
| Rated torque (max) | 557 Nm |
| Peak torque (max) | 762 Nm |
| Speed (max) | 68 rpm |
| Ratio | 81–121:1 |
| Sizes | 08, 11, 14, 17, 20, 25, 32, 40 |
| Resolution (max) | 20 bit |
| Accuracy | < 50 arc-sec |
| Interface | EtherCAT, CANopen |
| Mass | 0.35–7.9 kg |
| Encoder | Dual single-turn absolute 20-bit, BiSS-C |
| Supply | 24-48 VDC (48 VDC standard) |
Series ranges as published; individual models vary. The full datasheet, drawings and CAD models are available on request.
Options
- torque sensor (not with CANopen)
- holding brake (MGU-17 and up)
- MGU-DBG debug cable
Typical applications
What a harmonic actuator is
A harmonic actuator is a rotary servo actuator that combines a strain-wave gear, a servo motor, a position encoder and often a brake in one compact housing. Many have a hollow shaft for cables, and some include the servo drive with a fieldbus interface. The strain-wave gear gives a high ratio with near-zero backlash, while a precision output bearing carries the load directly. The actuator is ready to mount as a robot joint or precision rotary axis.
When engineers choose a harmonic actuator
Choose a harmonic actuator for robot joints, positioners and precision rotary axes where compact size, zero backlash and fast integration matter. It saves the design effort of combining motor, gear, encoder and bearings. The trade-offs are cost and flexibility: the motor, gear ratio and feedback are fixed by the range, and torque limits are set by the strain-wave gear. For heavy shock loads, a cycloidal solution may be more robust.
How to specify the MGU
Send these with your enquiry and an engineer can confirm the right MGU variant:
- Rated and peak output torque (Nm)
- Output speed (rpm)
- Ratio (:1)
- Hollow shaft diameter (mm)
- Feedback: motor-side and output-side encoders
- Brake and integrated drive options
- Supply voltage and interface
Common mistakes to avoid
- Exceeding momentary torque in a collision
- Ignoring output bearing moment load
- Mismatching drive and encoder interface
- Forgetting heat in continuous duty
MGU: frequently asked questions
Can you help replace MGU or source the original?
Send the full model code, quantity and required date. Our engineers can check original-part availability and assess suitable alternatives, including supply-network options where appropriate. We confirm compatibility and any changes needed before recommending a replacement.
What is the MGU?
Compact robot-joint harmonic actuator with built-in EtherCAT/CANopen drive, dual 20-bit encoders and optional torque sensor, from 0.35 kg; aimed at humanoids and cobots. Published series figures include bore 6.5 mm, bore 23 mm, rated torque 557 Nm, peak torque 762 Nm. It is available through our supply network, and our engineers can confirm the right variant for your application.
Who makes the MGU?
The MGU is part of a range available through our supply network. Send us your requirement for pricing, lead time, datasheets and CAD.
What is the bore of the MGU?
The published series minimum bore is 6.5 mm. Individual models and sizes in the MGU range vary, so check the exact variant against your duty cycle, mounting and environment, or ask our engineers to confirm the right size for you.
What is the benefit of dual encoders on a harmonic actuator?
A motor-side encoder controls the motor, while an output-side encoder measures the joint position directly after the gear. This compensates for gear deflection and gives true absolute output position at power-up. Dual encoders improve accuracy and support safety and collision detection.
Can a harmonic actuator include its own drive?
Yes, some versions integrate the servo drive and communicate over EtherCAT, CANopen or similar networks. This reduces cabinet space and wiring. Other versions connect to a separate servo drive. Choose by machine architecture, cabinet space and the safety functions needed, such as safe torque off or functional safety over the network.
Further reading: How to select a harmonic actuator · Harmonic vs planetary vs cycloidal · Gearboxes and harmonic drives
Often compared with
Engineers specifying this series often compare it with:
Other harmonic actuator series
Engineer support
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Prefer to configure it? Use the spec builder.
How it works
From enquiry to delivery
Send a part number or describe the application. Our engineers take it from there: the right product, a clear quotation, and delivery and support arranged.
- 01Tell us what you needSend a part number, or configure the application, quantities and timing.
- 02An engineer reviews itWe check the specification and find the original part, a checked equivalent or a complete axis.
- 03Receive your quotationProducts, pricing, lead time and compatibility notes in one reply.
- 04Order and deliveryWhen you are happy, the order is placed and delivery and after-sales support are arranged.