Harmonic Drive Actuator R48 Module for Wrist/Head
Product Overview
The Smallest Harmonic Drive Actuator That Still Delivers
The CrabNova R48 is the entry point into high-performance harmonic drive actuation — proof that you don't need bulk to get precision. At just 270 grams and a 48mm outer diameter, it's the lightest and most compact module in the CrabNova lineup, yet it packs 6.5 Nm of continuous torque (16 Nm peak) through a 101:1 harmonic reducer with 30 arcseconds of backlash.
What sets the R48 apart from other micro actuators is its dual-encoder architecture: a 19-bit single-turn absolute encoder on the output side, combined with a high-resolution motor-side encoder. This dual-feedback design delivers sub-arcminute positioning accuracy without homing routines — critical for wrist roll/pitch and head pan/tilt joints where every fraction of a degree matters.
The R48 is purpose-built for the lowest-inertia joints on a humanoid robot: head yaw and pitch, wrist roll, and compact end-effectors. With EtherCAT communication at 20 KHz current loop and 10 KHz speed loop, it responds fast enough for expressive head motion and dexterous wrist manipulation while adding negligible weight to the kinematic chain.
🎯 Why the R48 Matters: In humanoid robot design, every gram at the extremities compounds into exponentially higher torque demands at proximal joints. The R48's 270g weight at the wrist or head means your shoulder and waist actuators can be smaller, lighter, and more efficient — a cascading benefit across the entire kinematic chain.
Technical Specifications
Complete Parameter List
Based on CrabNova CE-RB-R48-101-DNN-CO-I product specifications. All values verified against manufacturer documentation.
⚙️ Mechanical Specifications
| Parameter | Specification | Notes |
|---|---|---|
| Model | CE-RB-R48-101-DNN-CO-I | Standard Series |
| Reduction Ratio | 101:1 | Harmonic drive |
| Rated Torque | 6.5 Nm | Continuous output |
| Peak Torque | 16 Nm | Transient peak |
| Output Speed | 30 RPM | At rated load |
| Backlash | 30 arcsec | Harmonic drive precision |
⚡ Electrical Characteristics
| Parameter | Specification | Notes |
|---|---|---|
| Rated Voltage | 48V DC | Industrial standard |
| Rated Power | 62.4 W | Continuous |
| Rated Speed | 2500 RPM | Motor shaft |
| Rated Current | 1.3 A | — |
| Peak Current | 3.2 A | Transient |
📡 Control & Sensing
| Parameter | Specification |
|---|---|
| Encoder | Dual encoders, single-turn absolute: 19 bits per revolution |
| Control Interface | EtherCAT / CANOpen / CAN FD |
| Current Loop | 20 KHz |
| Speed Loop | 10 KHz |
📏 Physical Dimensions
| Parameter | Specification |
|---|---|
| Dimensions | R48 × 53.6 mm |
| Weight | 0.27 kg (270 g) |
| Target Applications | Head yaw/pitch, wrist roll/pitch |
Key Features
Why the R48 Excels in Compact Joints
Ultra-Light Design
At just 270 grams, the R48 is the lightest harmonic drive actuator available in the 48mm class. This weight is critical for end-of-chain joints: every gram saved at the wrist reduces the reflected inertia seen by the elbow and shoulder actuators by a factor proportional to the square of the link length. An integrated design eliminates separate motor, reducer, encoder, and drive mounting — a single bolt-on module.
🎯 19-Bit Absolute Positioning
The R48 features dual-encoder architecture with a 19-bit single-turn absolute encoder on the output side (524,288 counts/rev, ~2.5 arcseconds theoretical resolution), paired with a high-resolution motor-side encoder. Combined with the harmonic drive's 30 arcsec backlash spec, this delivers reliable sub-arcminute real-world positioning without homing routines — critical for wrist roll/pitch and head pan/tilt joints where repeatability matters more than raw encoder bits.
🔌 Triple Protocol: EtherCAT + CANOpen + CAN FD
Supports EtherCAT for high-performance real-time control, CANOpen (CiA 402) for compatibility with existing robot control stacks, and CAN FD for bandwidth-flexible applications. The 20 KHz current loop and 10 KHz speed loop provide an order-of-magnitude faster control than the Lite variant — enabling responsive torque control and smooth velocity regulation even in demanding dynamic applications. Fully compatible with JxServo Studio for configuration, tuning, and diagnostics.
📐 Best-in-Class Power Density
With a torque density of 24 Nm/kg (rated) and 59 Nm/kg (peak), the R48 outperforms most actuators in its size class. The 101:1 harmonic drive delivers zero-backlash motion with 30 arcsec positional accuracy. The compact R48×53.6mm form factor fits into joint spaces where every millimeter counts — neck assemblies, wrist roll joints, and compact end-effectors.
Application Scenarios
Where the R48 Is the Right Choice
🤖 Humanoid Head Joints
The R48 is the default choice for head yaw and pitch on humanoid robots. At 270g, it adds minimal weight above the torso center of mass, preserving balance. The 19-bit absolute encoder provides the smooth, precise motion needed for expressive social robots and accurate camera/sensor pointing. 30 RPM is ample for natural head movement speeds.
✋ Wrist Roll & Pitch
The most swing-weight-sensitive joint on any robot arm. The R48's 270g mass at the wrist keeps the forearm's moment of inertia low, enabling faster elbow and shoulder motion with less torque. 6.5 Nm handles typical wrist loads for end-effectors up to 2–3 kg. The compact 48mm diameter matches the natural proportions of human-scale robot wrists.
🔬 Research & Education Platforms
The R48's combination of low cost, EtherCAT+CAN FD open protocol, and JxServo Studio support makes it ideal for university robotics labs and research platforms. Students and researchers get full access to torque, position, and velocity control loops without proprietary black-box firmware. The 19-bit absolute encoder provides research-grade positioning data.
📷 Camera Gimbals & Sensor Mounts
Beyond humanoid robots, the R48 serves precision pan/tilt applications: camera gimbals, LiDAR mounts, and sensor turrets on mobile robots and drones. The zero-backlash harmonic drive eliminates image jitter, while the absolute encoder means the gimbal knows its position immediately on power-up — no homing dance required.
What's Included
Package Contents
Every R48 order ships with everything needed for bench-top evaluation and integration.
| # | Item | Qty | Description |
|---|---|---|---|
| 1 | CrabNova R48 Actuator | 1 | Fully assembled and factory-calibrated joint module |
| 2 | Communication Cable | 1 | CAN/CAN FD interface cable with standard connector |
| 3 | Power Cable | 1 | 48V DC power connection cable |
| 4 | Mounting Hardware | 1 set | M3/M4 socket head screws for flange mounting |
| 5 | Product Datasheet | 1 | Technical specifications, mechanical drawings, and pinout |
| 6 | Software Access | — | JxServo Studio download + CANopen protocol documentation |
💻 Software & Resources: All CrabNova actuators are supported by JxServo Studio for configuration, tuning, and real-time telemetry. CANopen object dictionary and MIT mode documentation available at docs.juxieservo.com.
Why Buy from RobX
Sourced in China, Supported in California
When you buy a CrabNova R48 from RobX, you get more than a component. You get a partner who speaks your language — literally and technically.
US-Based PhD Technical Support
Your technical questions answered by a robotics PhD in California — in fluent English, during US business hours. No timezone delays, no translation errors. We help with sizing, integration, and tuning.
California Sample Inventory
Units stocked in California for immediate evaluation. Test in your lab within days — not weeks. No customs clearance, no freight forwarding, no surprises.
DDP Pricing & Full Logistics
All pricing is DDP (Delivered Duty Paid). We handle export, freight, customs, and import duties. You receive one invoice and one delivery.
Direct Manufacturer Relationship
As an authorized distributor of CrabNova (Juxie Intelligent Drive), we get priority allocation, direct engineering escalation, and advance notice of firmware and product updates.
