SimpleFOC Gimbal-BLDC Balancing Robot

A two-wheel self-balancing robot that uses quiet gimbal BLDC motors under field-oriented control instead of geared DC motors. An MPU6050 measures pitch, two encoders track the wheels, and a cascaded PID loop keeps the robot upright while you drive it from a Bluetooth joystick app.

Updated for modern use: a rewritten build guide, a current-parts Bill of Material and firmware notes for the current SimpleFOC library.

What you build

• 3D-printed center frame, two wheels, a modular MCU holder and a top plate
• Two 4108-class gimbal BLDC motors with incremental encoders
• ESP32 (D1 R32) with two stacked SimpleFOC Shields
• MPU6050 IMU and a 3S LiPo pack

Files

• Print-ready STL files: center frame, wheel (print two), MCU holder and top plate
• Editable SolidWorks parts for the printed pieces
• Build guide PDF: printing, assembly, wiring, firmware and tuning
• Bill of Material PDF with quantities, notes and a shop link for every part

Print settings

PLA or PETG. Frame and MCU holder 30% infill; top plate 20%; wheels 30% at 0.10–0.15 mm layers for an accurate motor fit. Check your motor and encoder hole spacing against the frame before printing.

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.

Firmware and full build guide

Firmware source, the build guide and all project files: https://github.com/ToolKnox/hawkridge-simplefoc-bldc-balancing-robot (Code > Download ZIP).

Safety

LiPo packs can catch fire if shorted, over-discharged or charged without a balance charger. Before the first power-up, set the firmware supply voltage to your pack voltage; the original sketch assumes 8 V while the build uses a 3S pack (see the build guide). Keep fingers clear of the wheels when enabling the motors; the controller can drive them hard when it loses balance.