ZeroBug Hexapod

ZeroBug is a 3D-printed micro-servo hexapod from Maximilian Kern (CoretechR), designed as a compact, low-cost teaching platform for inverse kinematics, gait generation, and embedded locomotion control. Eighteen SG90-class hobby servos (three per leg) give the robot the full coxa-femur-tibia kinematic chain needed for smooth, 3D body pose control — the same degree-of-freedom layout used by commercial research hexapods at a fraction of the cost.

The control architecture is the interesting bit. A Raspberry Pi Zero acts as the high-level brain and user-interface host: it serves a web dashboard (joystick, keyboard, multitouch, Bluetooth gamepad inputs) and streams MJPEG video from the Pi camera. An STM32F103 ("Blue Pill") board handles the real-time dirty work — inverse kinematics for all 6 legs, tripod/wave gait generation, and the 18 servo PWM channels — because running those loops reliably on Linux is a losing battle. The Pi and STM32 communicate over UART with a simple framed protocol. This "dumb but real-time microcontroller + smart but latency-tolerant SBC" pattern is a great template for any Pi-based locomotion robot.

The included front 2-finger gripper makes ZeroBug unusual among hobby hexapods — most are pure walkers, but ZeroBug can actually pick up objects. This opens up simple mobile-manipulation demos: walk to a target, pose-align the body, grab, carry, release.

This program exposes cloud-side locomotion endpoints (directional walk with speed, yaw turn, full 6-DOF body pose, wave animation, gripper open/close, emergency stop) that relay to the Pi Zero's web backend over WebSocket, which in turn commands the STM32 over UART.

Credit to Maximilian Kern (CoretechR) — upstream repository at https://github.com/CoretechR/ZeroBug under GNU GPLv3. Full build log at coretecrobotics.de.

Printing

All 10 STL files match the upstream CoretechR/ZeroBug CAD Files/ set 1:1 — the list is already correct and complete. Note the print quantities, since the static Print-All set lists each file once:

• Per-leg parts (print x6 — once per leg): Coxa.stl, femur.stl, Tibia.stl, Sock.stl. ZeroBug is a 6-leg hexapod with an identical coxa-femur-tibia-foot chain on every leg, so each of these is printed six times (18 leg segments + 6 feet total).
• Body (print x1): Body-Top.stl and Body-Bot.stl form the two-part central chassis that sandwiches the electronics.
• Spacer.stl (print x6+): servo-mount / joint spacer; print at least one per leg (six), more if you want spares — small part.
• Front gripper (print x1 each): gripper_body.stl, plus the mirrored jaw pair gripper_clawL.stl + gripper_clawR.stl (both required — they are left/right mirrors, not alternates). The gripper is optional if you only want a walker, but it is the feature that distinguishes ZeroBug from typical hobby hexapods.

No duplicates, simulation meshes, alternates, or assembly-reference blobs are present. Servos (18x MG90S-class), the Raspberry Pi Zero, STM32F103, camera, battery, and electronics are sourced from the BOM — not printed.