Open Duck Mini v2 Bipedal Walking Robot

Open Duck Mini v2 is a 42 cm tall, two-legged robot in the style of a cartoon duck droid. It walks on its own with a reinforcement-learning policy that runs on a Raspberry Pi Zero 2 W. Five servos per leg and four in the neck and head share one serial bus, and foot switches plus an IMU give the controller ground and balance feedback.

Updated for modern use: one clear build path for the walking robot, all parts to buy in one list with whole-number quantities, and a rewritten print and build guide.

What you build

• Trunk with bearings and heat-set inserts, plus front, middle and back body panels and a battery lid
• Two legs with five STS3215 servos each: hip yaw, hip roll, hip pitch, knee and ankle
• Feet with a TPU sole and two contact switches each
• A neck and head with four servos and two small antenna servos
• Optional head light and speaker parts

Files

• All 36 print-ready STL files for the body, legs, feet, neck and head
• Build guide PDF: print list, trunk, feet, legs, neck and head, electronics, first walk
• Bill of Material PDF with quantities, notes and a shop link for every part

Print settings

PLA at 0.2 mm layers and 15% infill for every part except the two TPU foot soles (40% infill). Roughly 500 g of PLA in total. The print list in the build guide gives the count for each part.

Electronics

• 14 Feetech STS3215 7.4 V bus servos on a USB bus servo adapter
• Raspberry Pi Zero 2 W with a microSD card, fed by a 5 V UBEC
• BNO055 IMU and four foot contact switches
• 2S 18650 pack with BMS, XT30 lead, power switch and USB-C charger board

Bill of Material

Every part you need to buy, with quantities, notes and shop links, is in the Bill of Material PDF in the files of this model.

Software

The robot runs the Open Duck Mini runtime on the Pi with a trained walking policy. Set every servo ID and zero position on the bench before assembly; the build guide shows the order.

Full build guide and source

The build guide, source and all project files: https://github.com/ToolKnox/hawkridge-open-duck-mini-v2-bipedal-robot (Code > Download ZIP).

Safety

Buy the 7.4 V STS3215 servos; the 12 V version does not work with this battery. Use high-drain cells and the BMS, insulate every joint and never charge the pack unattended. Keep fingers out of the legs while the servos are powered.