Overview
The Brushless Actuator Module Core v1 is a light-weight, low-cost, minimal complexity, torque-controlled actuator module designed for robotic research. It features a brushless outrunner motor, high-resolution optical encoder, and a dual-stage timing belt transmission using primarily 3D printed parts and off-the-shelf components.Updated Version Available: The improved Actuator Module Core v1.1 is now available with the ODRI Encoder Kit.
Key Specifications
Weight
150g total assembly
Torque Output
2.5 Nm @ 12A
Segment Length
160mm
Core Components
The actuator module uses the same core components across all robot configurations described in the Open Robot Actuator Hardware repository. The only difference between modules is the surrounding shell structure.Core components weight: 95g (excluding shell structure)
Dual-Stage Transmission
The module employs a dual-stage timing belt transmission system:- First stage: 3:1 gear reduction
- Second stage: 3:1 gear reduction
- Total gear reduction: 9:1
Off-the-Shelf Components
Brushless DC Motor
T-Motor Antigravity 4004 300kVMotor Specifications
Motor Specifications
- 24 magnets / 12 pole pairs / 18 slots
- 3-phase WYE configuration (Star configuration)
- Rotor diameter: 45mm
- Weight: 53g
- Sold in sets of 2 pieces
Ordering Information
Ordering Information
Optical Encoder
Broadcom AEDT-9810-Z00- 5000 pulses per revolution per channel
- 20,000 counts per revolution at the microcontroller
- 5V two-channel quadrature output with index pulse (ABZ)
- Code wheel diameter: 26mm
- Weight: 5g
- Mouser: #630-AEDT9810Z00
- DigiKey: #516-3256-ND
Timing Belts
Conti Synchroflex AT3 GEN III - Heavy duty polyurethane with steel cord reinforcements| Stage | Length | Teeth | Width | Weight |
|---|---|---|---|---|
| First | 150mm | 50 | 4mm | 1.5g |
| Second | 201mm | 67 | 6mm | 3.0g |
Bearings
EZO Stainless Steel Miniature Roller Bearings (Total weight: 16g)Output Bearing
EZO 61705 2RS VA
- 32mm × 25mm × 4mm
- Weight: 6.9g
- Quantity: 2
Transmission Bearing
EZO MR84 VA
- 8mm × 4mm × 2mm
- Weight: 0.4g
- Quantity: 3
Tensioner Bearing
EZO 683 2Z VA
- 7mm × 3mm × 3mm
- Weight: 0.4g
- Quantity: 2
Fasteners
Total weight: 2.9g- Motor fasteners: M3 × 5 flat head screw (4 pieces)
- Timing belt tensioner fasteners: M3 × 10 flat head screw (2 pieces)
- Tensioner washers: M2.5 washer (2 pieces)
- Output shaft helical insert: Helicoil M3 × 6 (2 pieces)
- Encoder fasteners: M3 × 16 Phillips flat head screw - Polyamide plastic (2 pieces)
Machined Parts
Total weight: 5.9g Three components must be machined from metal:Motor Pulley
AT3 10-tooth pulley machined from aluminum
- Material: Aluminum
- Weight: 0.6g
- Technical drawing: motor_pulley_at3_t10.PDF
Center Pulley
AT3 10-tooth center pulley machined from aluminum
- Material: Aluminum
- Weight: 2.1g
- Technical drawing: center_pulley_at3_t10.PDF
Motor Shaft
Custom motor shaft from precision ground stainless steel
- Material: 4mm stainless steel rod (1.4301 EN10278 h9)
- Weight: 3.2g
- Technical drawing: motor_shaft.PDF
Alternative: You can order the ODRI Encoder Kit that includes all machined parts pre-assembled. See Actuator Module v1.1 for details.
3D Printed Parts
Total weight: 11.3g Print Direction: Positive Z direction of STL files for all components| Part | Weight | STL File |
|---|---|---|
| Encoder Codewheel PWB Mount | 0.3g | encoder_codewheel_pwb_mount.STL |
| Transmission Pulley AT3 T30 Center | 4.2g | transmission_pulley_at3_t30_center.STL |
| Transmission Pulley AT3 T30 Output | 6.7g | transmission_pulley_at3_t30_output.STL |
| Timing Belt Tensioner Roller (10mm) | 0.2g each | transmission_belt_tensioner_roller_10.0mm.STL |
Wiring and Connectors
Motor Phase Connectors
- Type: 2mm gold connectors (Reely RE-1373188)
- Quantity: 3 pairs
- Wire: LiY 0.50 mm² black cable
Encoder Connector
- Type: Hirose DF13 Socket 5-pin
- Crimp terminals: Hirose DF13-2630SCF (5 pieces)
- Wire: LifY 0.14 mm² (colors: red, yellow, black, white, green)
- Tool required: Hirose DF13 crimp tool
Encoder Wiring Convention
See source documentation for detailed wiring diagrams showing proper connection to the microcontroller.
Crimp Tool
Hirose DF13-TB2630HC crimp tool required for proper terminal installation.
Alternative Components
Encoder Options
- Option A (Default)
- Option B
- Option C
Broadcom AEDT-9810-Z00 encoder + separate PWB codewheel
- Encoder: Mouser #630-AEDT9810Z00 or DigiKey #516-3256-ND
- Codewheel: PWB Encoders Order #104768
- Mount: encoder_codewheel_pwb_mount.STL
Timing Belt Tensioner Options
- Option A (Default)
- Option B
7mm × 3mm × 3mm bearings (EZO 683 2Z VA) with 3D printed rollers
Assembly Documentation
Step-by-Step Instructions
Complete assembly guides available in source repository:
- Motor preparation
- Motor shaft preparation
- Encoder preparation
- Center pulley preparation
- Output pulley preparation
- Shell preparation
- Final module assembly
Testing Procedures
Actuator module testing procedures cover:
- Encoder calibration
- Motor phase identification
- Torque control verification
- Performance validation
Technical Resources
Technical Drawings
Complete PDF drawings available for all machined and custom parts in the source repository.
STL Files
All 3D printable component files provided in the source repository stl_files directory.
Assembly Guide
Detailed step-by-step instructions with photos for complete module assembly.
Bill of Materials
Complete BOM with part numbers and ordering information from multiple suppliers worldwide.
Related Pages
Actuator Module v1.1
See the updated version with ODRI Encoder Kit
Specifications
View complete technical specifications
Authors: Felix Grimminger License: BSD 3-Clause License Copyright: © 2019-2021 Max Planck Gesellschaft and New York University