Build openDog V3

Steps

14

Subassemblies

7

Hands-on time (sum)

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Critical path

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Your progress · this device

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14 steps have no time estimate; times above are lower bounds.

1. Preparation
   01

   Watch the build videos and open the CAD

   There is no written assembly guide. Watch the openDog V3 playlist linked from the README and open 'openDog V3.stp' (unzip 'CAD/openDog V3.zip', ~35 MB) alongside it. Also open 'openDog V3_internals_toleranced.stp' for the printable cycloidal internals, 'openDog V3_foot.stp' for the foot mould and 'Remote.stp'. Export each printable body to STL yourself.

   CHECKYou have STLs for every printed body you need and know from the video how each drive, leg and the body go together.

   Parts in

   —

   Tools

   STEP-capable CAD (Fusion 360, FreeCAD, Onshape import)

   Torque

   —

   Time

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   After

   Start

   Source

   youtube.com

2. Fabrication
   02

   Cut tubes, pins and output bolts

   Cut the four 1 m carbon tubes to the lengths in the CAD; the offcuts become the foot tubes. Cut 132 pieces of 4 mm steel bar to 31 mm. Cut the 60 M4 x 80 mm hex bolts to the length the drive output needs (from the CAD). Carbon dust is an irritant: cut wet or with extraction and a mask.

   CHECKLeg tubes match CAD length; 132 pins are 31 mm; output bolts are the same length.

   Parts in

   • Carbon fibre tube, 28 mm OD, 1 mm+ wall, 1 m length (cut to CAD lengths; offcuts make the foot tubes)structure.cf-tube-28
   • 4 mm steel bar cut to 31 mm (one per bearing mount around the outside of the cycloidal drives)structure.steel-pin-4x31
   • M4 hex head bolt, 80 mm (cycloidal output, 5 per drive, cut to length)fastener.m4x80-hex

   Tools

   Saw for carbon fibre (with dust extraction and mask), Hacksaw or cut-off tool, Calipers

   Torque

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   Time

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   After

   Start

   Source

   github.com

3. 03

   Print the drives, structure, feet mould and remote

   All parts are PLA. Large parts: 0.3 mm layers, 3 perimeters, around 15% infill. Cycloidal drive internals: 4 perimeters and 30-40% infill. Use the toleranced internals file for the drive parts (12 sets).

   CHECK12 complete sets of cycloidal internals plus all structure parts; pin and bearing bores accept the 4 mm pins and bearings without forcing.

   Parts in

   • Cycloidal disk 1 ('Planetary disk1'), tolerancedprinted.planetary-disk1
   • Cycloidal disk 2 ('Planetary disk2'), tolerancedprinted.planetary-disk2
   • Camprinted.cam
   • Cam capprinted.cam-cap
   • Top capprinted.top-cap
   • Bottom capprinted.bottom-cap
   • Upper mountprinted.upper-mount
   • All other printed parts (drive cases, legs, knee pulleys and idlers, body ends, electronics lid, stand): extract the bodies from 'openDog V3.stp' (inside 'openDog V3.zip'); no per-part list or STL set is publishedprinted.structure
   • Foot mould set (mouldA, mouldB, 2 sides, brace) for casting silicone feetprinted.foot-mould
   • Foot insert (cast into each silicone foot)printed.foot-insert
   • Remote base and lid (Remote.stp)printed.remote-case
   • Knee jig (openDogV3_jig_knee.stp; purpose not documented in the repo)printed.knee-jig

   Tools

   FDM printer

   Torque

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   Time

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   After

   01

   Source

   github.com

4. Electronics
   04

   Wire the Teensy 4.1, radio, LCD and control power

   From the code: ODrive 1-6 on Teensy Serial1-Serial6 at 115200 baud; NRF24L01 on SPI with CE pin 9 and CSN pin 10; 16x2 I2C LCD at 0x27; MPU6050 on I2C (experimental sketch only). Power the Teensy and radio from the 2S battery through the latching switch and the regulator set to 5 V. Use the 25-way D-sub pair as the connector between body electronics and the rest (per BOM; pinout not published).

   CHECKRegulator output reads 5.0 V before the Teensy is connected; the LCD shows 'openDog V3' when the firmware runs.

   Parts in

   • Teensy 4.1 (dog controller)compute.teensy-41
   • NRF24L01 2.4 GHz radio (one in the dog, one in the remote)electronics.nrf24l01
   • 16x2 LCD with I2C backpack (dog status, address 0x27)electronics.lcd-i2c
   • MPU6050 IMU (used only by the experimental_stability sketch)sensor.mpu6050
   • 5 V / adjustable step-down regulator (set to 5 V for the Teensy and dog electronics)power.reg-5v
   • Small 2S (or 3S) battery for the electronics, via the 5 V regulatorpower.lipo-2s
   • Latching push switch (electronics power)power.electronics-switch
   • 25-way D-sub connector, malecable.dsub25-male
   • 25-way D-sub connector, femalecable.dsub25-female
   • Panel volt metersensor.panel-voltmeter

   Tools

   Soldering iron, Multimeter

   Torque

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   Time

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   After

   01

   Source

   github.com

5. Drives
   05

   Assemble twelve cycloidal drives

   Per drive, as the BOM notes describe (sequence from the CAD and videos): 32 small 12x4x4 bearings on the 4 mm pins, each pin with a nylon washer top and bottom and 16 nylon spacers; 11 steel pins around the outside; 3 cam/cap bearings (32x20x7); 2 large 85x65x10 bearings top and bottom; the cam on an M4 x 40 socket screw with a locknut and 4 M3 x 15 screws; 5 cut M4 output bolts with washers and locknuts; motor on 4 M4 x 12 countersunk screws; case closed with 22 x 2.9 x 18 mm screws. The code assumes a 10:1 reduction (one motor turn = 36 degrees of output).

   CHECKEach drive back-drives smoothly by hand through a full output turn with no binding or knocking; 10 motor turns give one output turn.

   Parts in

   • 9225 90 KV brushless motor (HobbyKing/Turnigy Multistar 9225 90 KV or EaglePower 8308 stator / 9225 can 90 KV)actuator.bldc-9225-90kv
   • Ball bearing 12 mm OD x 4 mm ID x 4 mm (cycloidal drive internals, 32 per drive)structure.bearing-12x4x4
   • Nylon washer, 4 mm ID (top and bottom of each drive pin, 32 per drive)other.nylon-washer-4mm
   • Nylon spacer, 4 mm ID, 5 mm long (16 per drive)other.nylon-spacer-4x5
   • 4 mm steel bar cut to 31 mm (one per bearing mount around the outside of the cycloidal drives)structure.steel-pin-4x31
   • Ball bearing 32 mm OD x 20 mm ID x 7 mm (cam and cap, 3 per drive)structure.bearing-32x20x7
   • Ball bearing 85 mm OD x 65 mm ID x 10 mm (drive top/bottom, 2 per drive)structure.bearing-85x65x10
   • M4 countersunk screw, 12 mm thread (motor mounts, 4 per motor)fastener.m4x12-csk
   • M4 socket cap screw, 40 mm thread (cycloidal cam, 1 per drive)fastener.m4x40-socket
   • M4 nylon-insert locknut (cycloidal cam, 1 per drive)fastener.m4-locknut-cam
   • M3 screw, 15 mm thread (cycloidal cam, 4 per drive)fastener.m3x15
   • M4 hex head bolt, 80 mm (cycloidal output, 5 per drive, cut to length)fastener.m4x80-hex
   • M4 washer (cycloidal output, 5 per drive)fastener.m4-washer
   • M4 nylon-insert locknut (cycloidal output, 5 per drive)fastener.m4-locknut-output
   • 2.9 mm x 18 mm countersunk Pozidriv self-tapping screw (drive cases, 22 per drive, front and back)fastener.screw-2-9x18-case
   • Cycloidal disk 1 ('Planetary disk1'), tolerancedprinted.planetary-disk1
   • Cycloidal disk 2 ('Planetary disk2'), tolerancedprinted.planetary-disk2
   • Camprinted.cam
   • Cam capprinted.cam-cap
   • Top capprinted.top-cap
   • Bottom capprinted.bottom-cap
   • Upper mountprinted.upper-mount
   • All other printed parts (drive cases, legs, knee pulleys and idlers, body ends, electronics lid, stand): extract the bodies from 'openDog V3.stp' (inside 'openDog V3.zip'); no per-part list or STL set is publishedprinted.structure

   Tools

   Hex keys, Pozidriv screwdriver

   Torque

   —

   Time

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   After

   03, 02

   Source

   github.com

6. Legs
   06

   Cast the silicone feet

   Assemble the printed mould (mouldA, mouldB, sides, brace) around a foot insert and cast Shore 25A platinum-cure silicone with pigment. Glue the carbon foot tube into the lower leg and the foot insert so it cannot rotate.

   CHECKFour cured feet with the insert fully embedded; the foot tube does not turn in the insert or the lower leg.

   Parts in

   • Foot mould set (mouldA, mouldB, 2 sides, brace) for casting silicone feetprinted.foot-mould
   • Foot insert (cast into each silicone foot)printed.foot-insert
   • Platinum-cure silicone rubber, Shore 25A, with pigment (cast feet)other.silicone-25a
   • Carbon fibre tube, 28 mm OD, 1 mm+ wall, 1 m length (cut to CAD lengths; offcuts make the foot tubes)structure.cf-tube-28
   • Adhesive to glue the carbon foot tube into the lower leg and foot insert (type not specified)other.epoxy

   Tools

   Mixing cups and scale, Mould release

   Torque

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   Time

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   After

   03, 02

   Source

   github.com

7. Remote
   07

   Build the remote

   From Remote.ino: buttons and switches on Teensy LC pins 0-8 with internal pull-ups (buttons on 0-3, toggles on 4-8), joystick axes on A1, A2, A4-A7, NRF24L01 on SPI, and an I2C LCD at 0x27 (20x4 in the code). Include the 'reverse' switch and the motor-enable switch the README describes. The remote's battery and LCD are not in the BOM.

   CHECKWith Remote.ino running the LCD shows 'Everything Remote' and each switch/axis changes the transmitted values.

   Parts in

   • Teensy LC (remote controller)compute.teensy-lc
   • NRF24L01 2.4 GHz radio (one in the dog, one in the remote)electronics.nrf24l01
   • 3-axis joystick (remote)electronics.joystick-3axis
   • On/off toggle switch (remote)electronics.toggle-switch
   • Momentary push switch (remote)electronics.push-switch
   • Remote base and lid (Remote.stp)printed.remote-case

   Tools

   Soldering iron

   Torque

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   Time

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   After

   03

   Source

   github.com

8. Drives
   08

   Fit AS5047P encoders and run shielded cables

   Mount one AS5047P on each motor and wire it to its ODrive with 6-core foil-shielded cable: SCK, MISO, MOSI, GND and 3.3 V to the ODrive pins of the same name, chip select to a free GPIO (GPIO 1 and 2 are the UART used by the Teensy).

   CHECKEach encoder has continuity on every conductor to its ODrive header and the shield is not shorted to a signal.

   Parts in

   • AMS AS5047P motor encoder board (one per axis, absolute SPI mode)sensor.as5047p
   • 6-core foil-shielded signal cable for encoders (metres; 'make sure you have enough')cable.encoder-6core-shielded

   Tools

   Soldering iron

   Torque

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   Time

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   After

   05

   Source

   docs.odriverobotics.com

9. Legs
   09

   Assemble the legs and knee belt drives

   Per leg (from the CAD and videos): two 608 knee bearings, four 626 belt-idler bearings, one 37x30x4 thin-section bearing (plus two in each end bracket), the 630 mm HTD 5M knee belt, carbon tubes and the leg screws. Mount the hip drives on the side-to-side axis with 12 screws per drive.

   CHECKEach knee moves through its range by turning the knee drive by hand with the belt tensioned and not skipping; hips swing without rubbing.

   Parts in

   • HTD 5M pitch timing belt, 630 mm length (knee drive)structure.belt-htd5m-630
   • Ball bearing 22 x 8 x 7 mm (knee joints, 2 per leg)structure.bearing-608
   • Ball bearing 19 x 6 x 6 mm (knee belt idlers, 4 per leg)structure.bearing-626
   • Thin-section bearing 37 x 30 x 4 mm (one per leg and two per end bracket)structure.bearing-61706
   • Carbon fibre tube, 28 mm OD, 1 mm+ wall, 1 m length (cut to CAD lengths; offcuts make the foot tubes)structure.cf-tube-28
   • 2.9 mm x 18 mm countersunk Pozidriv screw (legs; BOM says '18 per leg' but lists 56)fastener.screw-2-9x18-leg
   • 2.9 mm x 18 mm countersunk Pozidriv screw (side-to-side axis mounts, 12 per drive for 4 drives)fastener.screw-2-9x18-axis
   • All other printed parts (drive cases, legs, knee pulleys and idlers, body ends, electronics lid, stand): extract the bodies from 'openDog V3.stp' (inside 'openDog V3.zip'); no per-part list or STL set is publishedprinted.structure

   Tools

   Pozidriv screwdriver, Hex keys

   Torque

   —

   Time

   —

   After

   05, 06

   Source

   github.com

10. Bring-up
    10

    Flash the dog and remote firmware

    Open Code/openDogV3/openDogV3.ino (with kinematics.ino, ODriveInit.ino, thresholdSticks.ino in the same folder) and upload to the Teensy 4.1; upload Code/Remote/Remote.ino to the Teensy LC. The two sketches share a data struct that must match exactly.

    CHECKThe dog LCD shows the remote connection state and 'S:' mode number changing when the remote's menu buttons are pressed.

    Parts in

    • Teensy 4.1 (dog controller)compute.teensy-41
    • Teensy LC (remote controller)compute.teensy-lc

    Tools

    Arduino IDE with Teensyduino, Libraries: ODriveArduino, RF24, LiquidCrystal_I2C, Ramp (and I2Cdev/MPU6050 for the experimental sketch)

    Torque

    —

    Time

    —

    After

    04, 07

    Source

    github.com

11. Electronics
    11

    Wire the 6S main battery, E-stops and ODrives

    Safety · human-verified required

    Connect the six ODrives (hips on ODrive 1 and 4; knees and shoulders on 2, 3, 5, 6 per the offsets in the code) and their motors to the 6S high-drain pack through the latching E-stop switch(es), with a volt meter on each battery circuit. The pack can source very large currents: size wire and connectors for it, insulate every joint, check polarity before first connection, and charge only with a balance charger. Wire gauge, fusing and the exact E-stop placement are not documented upstream.

    CHECKWith the E-stop open no ODrive powers up; with it closed every ODrive LED comes on and the volt meter shows pack voltage.

    This step can hurt a person or ruin parts. Its instructions need sign-off by a human who has done it before relying on them. Stop and ask if anything differs from what you see.

    Parts in

    • 6S high-drain LiPo main battery (maker's is 60C; e.g. ZIPPY Compact 4000 mAh 6S 60C)power.lipo-6s
    • LiPo balance charger suitable for the 6S pack (BOM.ods: 'requires suitable balance charger'; no model given)power.lipo-charger
    • Latching push switch used as E-stoppower.estop
    • Panel volt metersensor.panel-voltmeter
    • ODrive v3.6 BLDC driver (2 axes each)electronics.odrive-v36
    • 9225 90 KV brushless motor (HobbyKing/Turnigy Multistar 9225 90 KV or EaglePower 8308 stator / 9225 can 90 KV)actuator.bldc-9225-90kv

    Tools

    Soldering iron, Multimeter, Heavy-gauge wire and connectors (not specified upstream)

    Torque

    —

    Time

    —

    After

    08, 09, 04

    Source

    github.com

12. Bring-up
    12

    Configure and calibrate each ODrive axis

    Safety · human-verified required

    Legs off the ground or on the stand. For each axis in odrivetool, following the ODrive docs the README points to: set motor parameters and run motor calibration; set `axis.encoder.config.abs_spi_cs_gpio_pin = <cs pin>`, `axis.encoder.config.mode = ENCODER_MODE_SPI_ABS_AMS`, `axis.encoder.config.cpr = 2**14`, `odrv.save_configuration()`, `odrv.reboot()`; then `axis.requested_state = AXIS_STATE_ENCODER_OFFSET_CALIBRATION`, `axis.encoder.config.pre_calibrated = True`, `odrv.save_configuration()`. Per the README, `import math` and set `controller.config.vel_limit` and `vel_limit_tolerance` to `math.inf` so the motors do not disarm. Calibration spins the motors: keep hands out of the drives.

    CHECKEvery axis enters closed-loop control after a reboot without re-calibrating, and reported positions do not jump when powered off and on.

    This step can hurt a person or ruin parts. Its instructions need sign-off by a human who has done it before relying on them. Stop and ask if anything differs from what you see.

    Parts in

    • ODrive v3.6 BLDC driver (2 axes each)electronics.odrive-v36
    • AMS AS5047P motor encoder board (one per axis, absolute SPI mode)sensor.as5047p

    Tools

    odrivetool (ODrive v3.x firmware, 0.5.x docs), USB cable

    Torque

    —

    Time

    —

    After

    11

    Source

    github.com

13. 13

    Set joint offsets and first motion on the stand

    Safety · human-verified required

    Dog on its stand, motor-enable switch on, E-stop in reach. Menu 1 puts motors in closed loop (ODriveInit sets `motor.config.current_lim` to 20 A per axis); 2 moves legs out to clear the stand stirrups by 1-2 mm; 3 puts shoulders and knees at 45 degrees. Adjust the `offSet10` ... `offSet61` variables (turns; 1 turn = 36 degrees at the output) until mode 3 matches the CAD pose, then re-flash. Menu 10 returns the feet to the stirrups. Large leg motions happen quickly: stand clear.

    CHECKMode 3 holds all twelve joints at the CAD default pose; modes 2 and 10 clear and re-seat the stirrups without contact.

    This step can hurt a person or ruin parts. Its instructions need sign-off by a human who has done it before relying on them. Stop and ask if anything differs from what you see.

    Parts in

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    Tools

    —

    Torque

    —

    Time

    —

    After

    12, 10

    Source

    github.com

14. 14

    Raise gains, IK demo and walking

    Safety · human-verified required

    Menu 4 raises position, velocity and integrator gains (knee/shoulder 20, hips 60, velocity 0.1 in the code); 5 is the inverse-kinematics demo for six axes of translation and rotation; 6 is walking. The remote's reverse switch flips four axes to walk backwards. The dog stops if the radio link drops for 500 ms. Start in open space with the E-stop held by a second person.

    CHECKIn mode 5 the body follows the sticks smoothly; in mode 6 the dog steps in place and walks forward/back without a leg faulting.

    This step can hurt a person or ruin parts. Its instructions need sign-off by a human who has done it before relying on them. Stop and ask if anything differs from what you see.

    Parts in

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    Tools

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    Torque

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    Time

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    After

    13

    Source

    github.com

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