Build Your Own Quadruped Robot for Under $50

Robot dogs are one of the best things going in the world of robotics right now. Outside of carefully controlled demonstrations, humanoid robots appear to be best suited for tasks that involve falling down or otherwise malfunctioning in hilarious ways. However, the quadrupedal design of robot dogs gives them far more stability and agility. So much so that these robots are heavily used in a wide range of real-world applications today.

That utility generally comes with a heavy cost, however. Commercial-grade systems easily cost tens of thousands of dollars, and even hobbyist-grade robots frequently cost several hundred dollars. If you just want to experiment with this technology in your free time for fun, that is pretty steep.

If you are willing to do some work to build your own robot dog, then there is a less expensive option. A maker who goes by the name Thinking Things recently released a guide that shows how a reasonably capable mini robot dog can be assembled for just $50 in parts. That’s cheap enough that just about anyone with an interest in robotics can get in on the game.

Named “Albert,” the small quadruped is a fully 3D-printed, modular robot powered by an ESP32 microcontroller and built around off-the-shelf components like an Adafruit PCA9685 16-channel PWM servo driver. The design calls for eight servos to control the legs — two degrees of freedom per leg — plus an additional servo for the neck. Everything runs from a 5V supply, with the creator demonstrating how to hack a $5 USB power bank to provide both a lithium cell and onboard charging and protection circuitry.

Albert’s secret sauce isn’t expensive hardware or complex inverse kinematics solvers. Instead, it relies on what the creator calls “gait primitives” — simple cosine-based motion patterns that generate fluid movement. A standard cosine wave drives the forward swing of the upper leg, while a rectified cosine wave ensures the lower leg only lifts during the swing phase. The result is a smooth, cycloidal foot trajectory that looks far more organic than the jerky, linear stepping often seen in beginner builds.

By shifting the phase of the cosine waves between legs, Albert produces a stable trot. Steering is handled through amplitude modulation: increasing the stride on one side causes the robot to turn in the opposite direction. The firmware also includes synchronized interpolation, ensuring all legs reach new positions simultaneously during transitions between poses. Pre-programmed actions like “gallop,” “sit,” and even a playful “handshake” add personality to the platform.

Control is flexible as well. Commands can be sent over USB serial or Bluetooth, and a custom parser allows manual positioning of individual servos in real time.

By open-sourcing the STL files, wiring diagrams, and firmware, the creator is treating Albert as more than just a budget robot dog. It’s a platform — one that lowers the barrier to entry and invites makers to experiment with gait algorithms and modular robotics without breaking the bank. Check out the GitHub repository for more details.