Week 1: Research and more Research

A project log for My Journey of Building a Performance Quadruped

Building a brushless quadruped for under $1000

Peter BuckleyPeter Buckley 04/22/2020 at 19:411 Comment

I have a huge project ahead of me, and in order to be successful i have to be as prepared as possible. I began looking into a whole bunch of open sourced quadrupeds. I mostly only looked at mammal like robots with two sets of parallel limbs. Not the spider like robots with 4 limbs 90 Degrees apart.  I found most of these mammal based quadrupeds fell into two categories. The first category is smaller servo based quadrupeds such as the Stanford Pupper and the SpotMicro. The second category are much larger BLDC motor based platforms such as Paul Gould's very cool Quadruped using cycloidal gear boxes and Charles Galambos' Dogbot.  I knew in the end i wanted to build one of these more powerful and capable bots that use brushless motors, but since im not very knowledgeable on the topic decided to start out with a simpler and cheaper servo based bots. It was a hard choice for me to pursue building the Stanford Pupper, the SpotMicro, or James Burtons smaller MiniDog. The first one i could take out of the running was the Stanford Pupper because even know it was the best performing dog and had source code already written for it, it required several custom machined parts. Even know I have a cnc machine and would be able to machine these parts, i know most people dont. It also called for servos that were almost $25 a piece which were most likely the reason for its high agility and performance, but i was not willing to shell out that much of my budget on the "learning robot". Then i had to decide between the Spotmicro or Minidog. I eventually landed on the mini dog due to it having more similarity in the structure to the larger bldc quadruped i wanted to build, and the fact that no one has released any code for it which would Force me to code it myself. I began 3d printing the parts from black and yellow PETG with relatively low 15% infill in order to keep the robot as light as possible. It was time for me to at least get a basic understanding of C++ and the Arduino IDE so I enrolled myself into a free course that many redditors recommended. Its taught by a professor at Harvard and known as Harvard CS50. The course is free to audit and due to the whole thing being prerecorded, lectures can be taken at anytime, at any pace. I was skeptical at first but the course really is something special. The professor is very enthusiastic and entertaining and teaches you most of the basic things to know to get started. I am only two weeks into the 12 week course but already feel way more comfortable in the subject. I will check in again next week in order to discuss the many open source BLDC projects that i can do after this first learning robot. But for Now, Peter Out.


Paul Gould wrote 04/24/2020 at 13:14 point

Good luck with your project. I've restarted my servo based quadruped after seeing James going back to a smaller servo based quad. Join the Odrive discord, some people are making the Pupper there.

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