I wanted to build a four-legged robot, but actuators are expensive, so I decided to design my own. I created a modular system with the goal of making every component reusable and the robot itself scalable. The target weight is around 5 kg. Each actuator is built around a BE4108 BLDC motor paired with a custom FOC controller. For prototyping, I am using the B-G431B-ESC1. The custom FOC controller is based on an STM32G491 and uses a TMC6200 gate drive