Developing From Scratch: Building the RAP Autonomous Quadruped Robot

Philippe Elie wanted to construct his own autonomous robot from scratch without relying on readily available kits and software packages, which led him on the path to designing his RAP (Robotic Autonomous Pet) — an autonomous quadruped robot. Elie initially wanted to build on top of the ROS platform, but decided to stay ‘bare metal,’ and thus designed his own code using C++ for operations and kinematics.

The RAP robot reminds me a little of Boston Dynamics early version of the SpotMini, and although RAP isn’t that advanced, it’s still a significant first step into designing autonomous robots. Elie created RAD using Fusion 360, and the robot is crafted out of 30 x15mm aluminum framing for the body, plus 12 x12mm frames for the stand. All the fittings were 3D-printed using Polymax PLA, which is inherently stronger than regular PLA.

As far as hardware goes, RAD is outfitted with a Teensy 2.6 board, which packs an FPU that benefits the robot’s inverse kinematics computations. The Teensy drives an SSC32U Lynxmotion board that powers 12X RDS3115 Metal gear digital servos, which actuate the robot’s 3-DOF legs. RAD features two power supplies — a 15A 5V Pololu for the electronics, with a 3V regulator for the Teensy, a 20W 7.2V power supply for the servos, along with a LiPo 3S 1800mAh battery.

The robot is equipped with a host of sensors, including Lidar for 2D mapping of its surroundings, an IMU for orientation and compass information, and foot pressure sensors for in-air leg movements. Elie listed his complete project build on his Hackaday page, where you can find all the files necessary to develop your own RAD.