Integrated robot joint actuator
Laifual Drive DC low-voltage joint modules integrated robot joint actuator
48 V harmonic joint modules with integrated servo driver, from L40I to L190I, ratios 51–121, 17-bit single and dual encoder options, and CANopen, CAN FD, EtherCAT or Modbus.
Key specifications
| Data / bus | CANopen, CAN FD, EtherCAT, Modbus |
|---|---|
| Supply | 48 VDC |
| Feedback | 17-bit single-turn with 16-bit multi-turn, single or dual encoder |
| Ratio | 51–121:1 |
| Resolution (max) | 17 bit |
| Brake | optional |
| Models | L40I, L52I, L60I, L70I, L80I, L90I, L110I, L142I, L170I, L190I, T (high-torque) series |
Summarised in our own words from Zhejiang Laifual Harmonic Drive Co., Ltd. (HKEX: 03952)'s published data; series maxima, individual models vary. Last checked 2026-10-30. Source 1
Notes on this data
Torque and mass not stated on the page. Commercialised from 2024 (company profile).
Specify Motion is not affiliated with Zhejiang Laifual Harmonic Drive Co., Ltd. (HKEX: 03952). Laifual Drive and DC low-voltage joint modules are used only to identify the product. Comparisons use published figures; always confirm against the current datasheet.
Typical applications
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Our experienced engineers are on hand, ready to help with your project. Whether you need the Laifual Drive DC low-voltage joint modules itself, help sourcing it, or a modified or custom design built around your load, speed and space, tell us what the machine has to do and we'll come back with the right option.
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What an integrated robot joint actuator is
An integrated robot joint actuator packages a brushless motor, a reduction gear, encoders, a servo drive and often a brake or torque sensor into one module that bolts in as a robot joint. Gearing may be planetary, strain-wave or cycloidal. Many are designed for legged robots, humanoids and cobots, with low gear ratios or quasi-direct drive to keep the joint back-drivable and responsive. Communication is typically over CAN or EtherCAT, with position, velocity and torque control modes.
When engineers choose an integrated robot joint actuator
Choose an integrated joint actuator to build robots faster with fewer parts, especially legged, humanoid, exoskeleton and collaborative robots. Back-drivable versions suit force control and impacts. The trade-offs are torque density, precision and industrial qualification: low-ratio designs trade output torque for transparency, and some units are aimed at research rather than production duty. For industrial arms with heavy duty cycles, a dedicated harmonic actuator or motor and gear set may be better.
How to specify the Laifual Drive DC low-voltage joint modules
Send these with your enquiry and an engineer can confirm the right DC low-voltage joint modules variant or an equivalent:
- Peak and continuous output torque (Nm)
- Output speed (rpm)
- Gear type and ratio
- Back-drivability and torque sensing
- Supply voltage (V DC)
- Communication interface and control modes
- Mass and size (kg, mm)
Common mistakes to avoid
- Using peak torque as continuous torque
- Ignoring thermal limits in legged robots
- Overlooking bus bandwidth with many joints
- Assuming research-grade units meet industrial life requirements
Laifual Drive DC low-voltage joint modules: frequently asked questions
What is the Laifual Drive DC low-voltage joint modules?
48 V harmonic joint modules with integrated servo driver, from L40I to L190I, ratios 51–121, 17-bit single and dual encoder options, and CANopen, CAN FD, EtherCAT or Modbus. Published series figures include ratio 51:1, ratio 121:1, resolution 17 bit. It is made by Zhejiang Laifual Harmonic Drive Co., Ltd. (HKEX: 03952); Specify Motion can help source it or propose an equivalent.
Who makes the Laifual Drive DC low-voltage joint modules?
The Laifual Drive DC low-voltage joint modules is made by Laifual Drive (Zhejiang Laifual Harmonic Drive Co., Ltd. (HKEX: 03952)) and is listed here for engineers comparing options. Specify Motion is not affiliated with Zhejiang Laifual Harmonic Drive Co., Ltd. (HKEX: 03952); brand names are used only to identify the product.
What is the ratio of the Laifual Drive DC low-voltage joint modules?
The published series minimum ratio is 51:1. Individual models and sizes in the DC low-voltage joint modules 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.
Is there an alternative to the Laifual Drive DC low-voltage joint modules?
Yes. Our engineers can propose an equivalent built around your load, speed and environment. An engineer confirms the fit against your application before recommending anything.
What is a quasi-direct-drive actuator?
A quasi-direct-drive actuator uses a high-torque motor with a low gear ratio, typically below about 10:1, so the joint is back-drivable and responds quickly to external forces. This suits legged robots and force control. The trade-off is lower output torque than high-ratio joints of similar size.
Why integrate the drive in a robot joint actuator?
Integrating the drive reduces cabling and lets each joint communicate over a shared bus, which simplifies robot design. It also allows the drive to sit close to the motor, improving control. The trade-off is that heat from both motor and drive must be managed inside the joint.
Further reading: How to select a harmonic actuator · Frameless motor sizing robot joints · Gearboxes and harmonic drives
Other integrated robot joint actuator series
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