We developed a light-weight, low cost, minimal complexity, torque-controlled actuator module for robotic research.
The actuator module consists of a brushless outrunner motor, a high resolution optical encoder, a dual stage timing belt transmission and mostly 3d printed parts and off-the-shelf components.
The module has a segment length of 160mm, weighs 150g and outputs 2,5Nm at 12A.
The updated version of the Brushless Actuator Module Core is documented here: Actuator Module Core v1.1
Actuator Module Assembly - core components with upper leg shell structure
We are using the same core components for all the robots described in this repository.
The only difference between the actuator modules is the surrounding shell structure.
We are using a dual stage timing belt transmission with a 3:1 gear reduction on each stage. The total gear reduction is 9:1.
Core components - the weight of all the components in the pictures is 95g
- T-Motor Antigravity 4004 300kV
- 24 magnets / 12 pole pairs / 18 slots
- 3 phase WYE Configuration / Star Configuration
- Rotor diameter: 45mm
- Weight: 53g
- Details Motor Preparation
- Details Motor Shaft Preparation
- T-Motor Product Webpage (the motors are sold in sets of 2 pieces)
- Ordering information below
- Broadcom AEDT-9810-Z00
- 5000 pulses per revolution per channel
- 20000 counts per revolution at the micro controller
- 5V two channel quadrature output with index pulse (ABZ)
- Code wheel diameter: 26mm
- Weight: 5g
- Details Encoder and Codewheel
- Details Encoder Preparation
- Details Motor Shaft and Codewheel Preparation
- Broadcom Webpage
- Ordering information below
Timing Belts AT3 GEN III with 50 teeth and 67 teeth - weight: 4,5g
- Timing Belt: Conti Synchroflex AT3 GEN III - 3mm tooth pitch
- Heavy duty polyurethane timing belt with steel cord reinforcements
- First stage: 150mm timing belt - 50 teeth - width 4mm - 1,5g
- Second stage: 201mm timing belt - 67 teeth - width 6mm - 3g
- Contitech Webpage
- Ordering information below
Stainless steel roller bearings - weight: 16g
- Miniature EZO stainless steel roller bearings
- Ouput bearing: 32mm x 25mm x 4mm - 6.9g
- Transmission bearing: 8mm x 4mm x 2mm - 0.4g
- Belt tensioner bearing: 7mm x 3mm x 3mm - 0,4g
- EZO Webpage
- Ordering information below
Fasteners Actuator Module Core - weight: 2,9g
- Fasteners Motor: M3 x 5 Flat Head Screw
- Fasteners Timing Belt Tensioner: M3 x 10 Flat Head Screw
- Washers Timing Belt Tensioner: M2,5 Washer
- Helical Insert Output Shaft: Helicoil M3 x 6
- Fasteners Encoder: M3 x 16 Philipps Flat Head Screw
- Ordering information below
Motor shaft, motor pulley and center pulley - weight: 5,9g
The 3 parts in the picture need to be machined from metal.
- motor pulley 10 teeth - aluminum - 0.6g -> PDF drawing
- center pulley 10 teeth - aluminum - 2,1g -> PDF drawing
- motor shaft - 4mm stainless steel rod - 3,2g -> PDF drawing
- Details Machined Parts and Technical Drawings
Alternatively you can order the ODRI Encoder Kit that includes all the machined parts.
More information can be found in the Actuator Module Core v1.1 Documentation.
3d printed parts - weight of the parts in the picture: 11,3g
The tooth profile of the pulleys has to be pretty precise and concentric.
We recommend to print all the parts listed below with a stereolithography or multijet printer.
More information: Details 3D Printed Parts
All the STL files for 3d printing the parts below can be found here: STL Files
The recommended printing direction for all the parts below is the positive z direction of the stl files.
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Encoder Codewheel PWB Mount - weight: 0,3g
STL file (Option A with Broadcom AEDT-9810-Z00 encoder) -
Encoder Codewheel Kit Mount - weight: 0,3g
STL file (Option B with AEDM-5810-Z12 encoder kit)
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Transmission Pulley AT3 T30 Center - weight 4.2g -> STL file
- Transmission Pulley AT3 T30 Output - weight 6.7g -> STL file
- Transmission Belt Tensioner Rollers - weight 0,2g each
- There are STL files with different outer diameters available
- the default diameter that we are using is 10mm
- the different roller diameters allow you to adjust the timing belt tension if required
- 10.0mm Transmission Belt Tensioner Roller -> STL file
- 10.5mm Transmission Belt Tensioner Roller -> STL file
- 11.0mm Transmission Belt Tensioner Roller -> STL file
- 11.5mm Transmission Belt Tensioner Roller -> STL file
| Description | Quantity | Ordering Information | Comments |
|---|---|---|---|
| T-Motor Antigravity 4004 300kV | 1 | T-Motor Store Globeflight # 1974 |
2 motors per set |
| Encoder Broadcom AEDT-9810-Z00 | 1 | Mouser # 630-AEDT9810Z00 DigiKey # 516-3256-ND |
Encoder without codewheel |
| Codewheel for Encoder AEDT-9810-Z00 | 1 | PWB Encoders GmbH # 104768 | Send an email to info@pwb-encoders.com and ask for a quote. PWB ships worldwide. Order number: 104768 / Codewheel with index / 625cpr 3K for AEDT98X / ID 7mm / OD 25,56mm |
| Timing Belt Conti Synchroflex AT3 GEN III width: 4mm / length: 150mm / 50 teeth Timing belt first stage |
1 | Reiff # 60047626 Beltingonline |
Reiff: The belt with 4mm width is not listed on the Reiff webpage. Send an email to e-services@reiff-gruppe.de and ask for a quote. Reiff ships within Europe. |
| Timing Belt Conti Synchroflex AT3 GEN III width: 6mm / length: 201mm / 67 teeth Timing belt second stage |
1 | Reiff # 60005258 Beltingonline |
Send an email to e-services@reiff-gruppe.de and ask for a quote. Reiff ships within Europe. |
| Bearing Output Shaft 32mm x 25mm x 4mm EZO bearing 61705 2RS VA |
2 | Emiliana Cuscinetti Doppiaemme EZO USA SBN Online Bearing Store |
Italy: Emiliana Cuscinetti or Doppiaemme USA: EZO USA All other countries: Send an email to info@sbn.de and ask for a quote - they ship worldwide. SBN # C02748 We use stainless steel bearings. Alternative: Chrome steel bearings from the Online Bearing Store |
| Bearing Motor Shaft and Center Shaft 8mm x 4mm x 2mm EZO bearing MR84 VA |
3 | Emiliana Cuscinetti Doppiaemme EZO USA SBN Online Bearing Store |
Italy: Emiliana Cuscinetti or Doppiaemme USA: EZO USA All other countries: Send an email to info@sbn.de and ask for a quote - they ship worldwide. SBN # N09724 We use stainless steel bearings. Alternative: Chrome steel bearings from the Online Bearing Store |
| Bearing Timing Belt Tensioner 7mm x 3mm x 3mm EZO bearing 683 2Z VA |
2 | Emiliana Cuscinetti Doppiaemme EZO USA SBN Online Bearing Store |
Italy: Emiliana Cuscinetti or Doppiaemme USA: EZO USA All other countries: Send an email to info@sbn.de and ask for a quote - they ship worldwide. SBN # N05560 We use stainless steel bearings. Alternative: Chrome steel bearings from the Online Bearing Store |
| Encoder Codewheel PWB Mount | 1 | STL file | 3d printed part - use SLA, Polyjet or Multijet printer |
| Transmission Pulley AT3 T30 Center | 1 | STL file | 3d printed part - use SLA, Polyjet or Multijet printer |
| Transmission Pulley AT3 T30 Output | 1 | STL file | 3d printed part - use SLA, Polyjet or Multijet printer |
| Timing Belt Tensioner Roller 10mm | 2 | STL file |
3d printed part - use SLA, Polyjet or Multijet printer |
| Motor Shaft | 1 | PDF drawing | Machined part |
| Motor Pulley | 1 | PDF drawing | Machined part |
| Center Pulley | 1 | PDF drawing | Machined part |
| Fasteners Encoder M3 x 16 Philipps Flat Head Screw |
2 | Conrad # 839967 | Polyamide plastic 10 pieces per set |
| Fasteners Motor M3 x 5 Flat Head Screw |
4 | Online Schrauben | Stainless Steel Online Schrauben ships within Europe. |
| Fasteners Timing Belt Tensioner M3 x 10 Flat Head Screw |
2 | Online Schrauben | Stainless Steel Online Schrauben ships within Europe. |
| Washers Timing Belt Tensioner M2,5 Washer |
2 | Online Schrauben | Stainless Steel Online Schrauben ships within Europe. |
| Helical Insert Output Shaft Helicoil M3 x 6 |
2 | RS # 470-834 Hoffmann # 082814 M3 McMaster # 91732A773 |
M3 Helicoil tools required |
Left side: Encoder and codewheel ordered seperately as described above
Right side: Alternative B - Encoder Kit - described below
| Description | Quantity | Ordering Information | Comments |
|---|---|---|---|
| Broadcom Encoder Kit AEDM-5810-Z12 | 1 | Mouser # 630-AEDM5810Z12 DigiKey # 516-3253-ND |
Kit consisting of encoder and codewheel Instructions Encoder Kit Disassembly |
| Codewheel Mount Encoder Kit | 1 | STL file | 3d printed part- use SLA, Polyjet or Multijet printer |
ODRI Encoder Kit Components
Alternatively you can order the ODRI Encoder Kit that includes all the machined parts, the code wheel and the encoder.
This option is documented here: Actuator Module Core v1.1 Documentation.
Left side: 7mm bearings and 3d printed rollers as described above
Right side: Alternative B - 10mm bearings - described below
| Description | Quantity | Ordering Information | Comments |
|---|---|---|---|
| Bearing Timing Belt Tensioner SKF # 623-2Z 10mm x 3mm x 4mm |
2 | RS Germany # 285-0807 Quality Bearings Online |
Alternative for 7mm x 3mm x 3mm bearing and timing belt tensioner roller above. |
| Fasteners Timing Belt Tensioner M3 x 10 Flat Head Screw |
2 | Online Schrauben | Stainless Steel Online Schrauben shipps within Europe. |
| Washers Timing Belt Tensioner M3 Washer |
2 | Online Schrauben McMaster # 90965A130 |
Stainless Steel Online Schrauben shipps within Europe. |
Connectors Actuator Module
| Description | Quantity | Ordering Information | Comments |
|---|---|---|---|
| Motor Phase Connectors 2mm gold Reely RE-1373188 |
3 | Conrad # 1373188 HobbyKing |
Conrad: 2 pairs per set HobbyKing 10 pairs per set |
| Motor Phase Wires LiY 0.50 mm² black |
3 | Kabeltronik # 1601050 Conrad # 609337 McMaster # 8054T14 |
Kabeltronik ships worldwide. 100m on spool. The Kabeltronik wires are the most flexible. |
| Encoder Connector Hirose DF13 Socket 5 Pin |
1 | RS # 143-015 DigiKey # H2182-ND |
The Hirose DF13 Crimp Tool is required for crimping the wires. RS # 503-8331 |
| Encoder Connector Crimp Terminals | 5 | RS 503-8325 Digi-Key H9992CT-ND |
The Hirose DF13 Crimp Tool is required for crimping the wires. RS # 503-8331 |
| Encoder Wires LifY 0.14 mm² |
5 | Kabeltronik # 1601014 | Kabeltronik ships worldwide. 100m on spool - different colors available. For the encoders we use red, yellow, black, white and green wires. |
Wiring Convention Encoder with Kabeltronik Wires
More wiring information here: Details Wiring
Actuator Module Overview - Click on picture to view PDF drawing.
| Motor Preparation | Motor Shaft Preparation | Encoder Preparation | Center Pulley Preparation |
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| Output Pulley Preparation | Shell Preparation | Actuator Module Assembly | Actuator Module Testing |
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| Details 3d Printed Parts | Details Machined Parts | Mechanical Tools and Consumables | Electronic Components and Tools |
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Open Dynamic Robot Initiative - Webpage
Open Dynamic Robot Initiative - YouTube Channel
Open Dynamic Robot Initiative - Forum
Open Dynamic Robot Initiative - Paper
Hardware Overview
Software Overview
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Felix Grimminger
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Copyright (c) 2019-2021, Max Planck Gesellschaft and New York University