Harmonic Drive Actuator R102 Model for Waist/Hip
Product Overview
The Torque King of the CrabNova Lineup
The CrabNova R102 is where the CrabNova lineup crosses into heavy-duty territory. With a 161:1 harmonic drive reduction ratio, 147 Nm continuous torque, and 350 Nm peak torque, it's purpose-built for the joint that bears the most load on any humanoid robot: the hip. At 2.6 kg and R102×89.6mm, it's a substantial module — but the numbers tell the story: this actuator can support the full weight of a humanoid robot through a walking gait cycle without thermal derating.
The R102's defining characteristic is its 161:1 reduction ratio. Compared to the 101:1 modules in the lineup, the deeper reduction trades output speed (18 RPM vs. 30 RPM) for dramatically higher torque — roughly 2.8× the torque of the R83 at a similar motor power (446W). The 18 RPM output speed is precisely matched to human walking cadence: a typical human hip joint rotates at 15–25 RPM during normal gait, so the R102 operates comfortably within its rated range during locomotion.
The R102 comes standard with the complete sensing and safety suite: a 1.5 Nm electromagnetic brake (≤100ms release, ≤50ms pull-in) for reliable power-off holding, and a 350 Nm rated torque sensor with an exceptional ±0.25% FS accuracy — the highest precision in the entire CrabNova product line. The 350 Nm sensor range covers the full 350 Nm peak torque exactly, with zero margin — a deliberate design choice that maximizes resolution at the cost of requiring careful overload management.
🎯 Why the R102 Matters: The hip joint is the single most torque-intensive actuator on a humanoid robot. During walking, the hip must support the entire upper body mass plus dynamic loads that can reach 2–3× body weight at heel strike. The R102's 147 Nm continuous rating means it can walk a 60–80 kg humanoid indefinitely without overheating — the dividing line between a lab demo and a field-deployable platform.
Technical Specifications
Complete Parameter List
Based on CrabNova CE-RB-R102-161-FBT-I (Upgraded) specifications. The R102 is offered in its fully-equipped configuration with brake and torque sensor as standard.
⚙️ Mechanical Specifications
| Parameter | Specification | Notes |
|---|---|---|
| Model | CE-RB-R102-161-FBT-I | Upgraded — Brake + Torque Sensor |
| Reduction Ratio | 161:1 | Optimized for maximum torque |
| Rated Torque | 147 Nm | Continuous |
| Peak Torque | 350 Nm | Transient — 2.4× rated |
| Output Speed | 18 RPM | Matched to walking cadence |
| Backlash | 30 arcsec | Harmonic drive precision |
⚡ Electrical Characteristics
| Parameter | Specification | Notes |
|---|---|---|
| Rated Voltage | 48V DC | Industrial standard |
| Rated Power | 446.4 W | Continuous |
| Rated Speed | 1800 RPM | Motor shaft |
| Rated Current | 9.3 A | — |
| Peak Current | 33.8 A | 3.6× rated — massive transient capability |
📡 Control & Sensing
| Parameter | Specification |
|---|---|
| Encoder | Dual encoders, single-turn absolute: 19 bits (524,288 counts/rev) |
| Control Interface | EtherCAT / CAN FD / CANOpen |
| Current Loop | 20 kHz |
| Speed Loop | 10 kHz |
| Brake | ≥1.5 Nm static holding torque (20°C), release ≤100 ms, pull-in ≤50 ms |
| Torque Sensor | 350 Nm rated range, overload 150% FS (525 Nm), RS485, ±0.25% FS |
📏 Physical Dimensions
| Parameter | Specification |
|---|---|
| Dimensions | R102 × 89.6 mm |
| Weight | 2.60 kg |
| Target Applications | Hip roll/pitch, waist yaw (large platforms), heavy base joints |
Key Features
Why the R102 Dominates Heavy Joints
🏋️ 161:1 Deep Reduction for Maximum Torque
The 161:1 harmonic drive is the defining feature of the R102. Compared to the 101:1 ratio used in smaller modules, the deeper reduction provides a 1.6× torque multiplier at the cost of 1.6× lower speed — a trade-off that's exactly right for hip and waist joints. At 18 RPM output, the R102 delivers 147 Nm from a 446W motor — a torque-to-power ratio of 0.33 Nm/W, the highest in the lineup. This efficiency means less heat, longer continuous duty cycles, and smaller battery requirements for mobile platforms.
🎯 ±0.25% Torque Accuracy — Best in Class
The R102's torque sensor achieves ±0.25% FS accuracy over a 350 Nm range — twice the precision of the ±0.5% sensors on smaller modules. At full scale, this translates to ±0.875 Nm of measurement uncertainty, enabling precise ground reaction force estimation and center-of-pressure tracking during walking. For researchers developing model-predictive control (MPC) or whole-body controllers, this level of torque fidelity is essential for stable locomotion on uneven terrain.
🛑 1.5 Nm Industrial-Grade Brake
The R102's electromagnetic brake delivers ≥1.5 Nm static holding torque at the output — enough to hold the hip joint of a 60–80 kg humanoid in a seated or standing position indefinitely on zero power. The ≤100ms release time is slower than the smaller modules' ≤50ms, reflecting the larger brake mass — but for a hip joint, this response time is still more than adequate. The ≤50ms pull-in time ensures rapid engagement when an emergency stop is triggered.
🔌 High-Current Drive for Peak Torque Delivery
The R102's drive stage handles a 33.8A peak current — 3.6× the 9.3A rated current. This massive transient capability is what enables the 350 Nm peak torque, which is essential for absorbing the 2–3× body weight impact forces at heel strike during walking. The 20 kHz current loop ensures the drive can modulate this current with sub-millisecond precision, preventing torque overshoot that could damage the harmonic drive or the robot's structure.
Application Scenarios
Where the R102 Is the Right Choice
Humanoid Hip Joints (Roll & Pitch)
The R102 is the reference actuator for humanoid hip joints. 147 Nm continuous handles the full upper-body mass (40–60 kg) through a walking gait cycle without thermal derating. 350 Nm peak absorbs the dynamic loads at heel strike and provides the explosive torque needed for stair climbing, jumping, and recovery from pushes. The ±0.25% torque sensor enables force-controlled walking with precise ground reaction force estimation.
🔄 Waist Yaw on Full-Size Humanoids
For humanoids above ~50 kg, waist yaw rotation demands the R102's 147 Nm — the R83 at 53 Nm simply cannot accelerate a full upper body fast enough for natural-looking torso rotation. The 161:1 ratio's 18 RPM output speed is well-matched to the ~10–15 RPM range of human torso rotation, and the 1.5 Nm brake holds the torso securely when the robot is stationary or unpowered.
🏗️ Heavy Industrial Robot Base Joints
The R102 serves as an excellent J1 (base rotation) actuator for industrial robot arms in the 10–20 kg payload class. 147 Nm continuous handles the full arm inertia at maximum reach, while 350 Nm peak provides the acceleration needed for high-throughput pick-and-place cycles. The brake holds the arm safely during tool changes or power-down, and the EtherCAT interface integrates with all major industrial controllers.
Industrial Exoskeleton Knees & Hips
For powered exoskeletons and wearable robotics, the R102's 147 Nm continuous torque directly supports human-scale knee and hip extension. The torque sensor's ±0.25% accuracy provides the fidelity needed for transparent impedance control — the exoskeleton follows the wearer's intent rather than imposing its own motion. The 1.5 Nm brake prevents collapse if the system loses power, a critical safety requirement for medical exoskeletons.
Variant Comparison: R102 Configurations
The R102 is available in three configurations to match different application requirements:
| Feature | R102-FBT-I (Upgraded) | R102-FBN-I (Waist) | R102-DBN-I (Waist) |
|---|---|---|---|
| Torque Sensor | ✅ 350Nm ±0.25% | — | — |
| Brake | ≥1.5 Nm | ≥1.5 Nm | 1.7 Nm |
| Interface | EtherCAT/CAN FD/CANOpen | EtherCAT/CANOpen | EtherCAT/CANOpen |
| Weight | 2.60 kg | 2.20 kg | 2.50 kg |
| Dimensions | R102×89.6mm | R102×90.3mm | R102×88mm |
| Best For | Force-control hip/knee | Lightest waist | Max brake torque |
What's Included
Package Contents
| # | Item | Qty | Description |
|---|---|---|---|
| 1 | CrabNova R102 Actuator | 1 | Fully assembled, factory-calibrated (with brake + torque sensor) |
| 2 | Communication Cable Set | 1 set | EtherCAT/CAN FD/CANOpen interface cables |
| 3 | Power Cable | 1 | 48V DC high-current power connection |
| 4 | Brake Control Cable | 1 | 24V brake release signal cable |
| 5 | Mounting Hardware | 1 set | Heavy-duty socket head screws for flange mounting |
| 6 | Product Datasheet | 1 | Technical specs, mechanical drawings, and pinout |
| 7 | Software Access | — | JxServo Studio + full protocol documentation |
| 8 | Calibration Certificate | 1 | Per-unit factory calibration data (encoder + torque sensor) |
💻 Software & Resources: All CrabNova actuators supported by JxServo Studio. Full CANopen object dictionary (including R102-specific 161:1 ratio parameters), EtherCAT ESI files, and MIT impedance mode guide at docs.juxieservo.com. Diagnostic fault codes (0x603F / 0x4500) and real-time telemetry frames (0xF1–0xF8) documented for production integration.
Why Buy from RobX
Sourced in China, Supported in California
US-Based PhD Technical Support
Your technical questions answered by a robotics PhD in California — in fluent English, during US business hours. We help with hip joint sizing, walking dynamics analysis, brake integration, and torque sensor calibration.
California Sample Inventory
R102 units stocked in California for immediate evaluation. Test the torque king in your lab within days — not weeks.
DDP Pricing & Full Logistics
All pricing is DDP (Delivered Duty Paid). We handle export, freight, customs, and import duties for these heavy modules.
Direct Manufacturer Relationship
As an authorized distributor of CrabNova (Juxie Intelligent Drive), we get priority allocation of R102 modules and direct engineering escalation for custom torque/speed configurations.
