Lots of ways to start. None of them are wrong. Just let your passions lead you to something you’d like to explore. Maybe start with a hackable 3D printing kit that will let you build parts for more robots. Hacking the 3D printer can directly teach you a lot about robotics.

https://simplefoc.com/ Is my type of rewarding nerdy topic. You might be more attracted to other control strategies.

Mastering robotics as a DIY thing is usually more about the mechanical (particular linkages and kinematics) as well as electrical (particularly motor control). The programming part of it generally can be lower quality and more hacked together, but still can be an area of deep exploration if that’s your passion.

https://youtu.be/pJj6uGcMco4?si=J0ui8LzYxEBXePZ0 ‘Engineer Bo’ is a small YT channel with a few great videos about stepper motor control. This video is about protecting the motor driver chip from large surges of electricity when the motor tries to wuickly “brake”. There’s a second video where he iterates on this solution.

If you don't find the mechanical and electrical parts something you want to invest enough time in to learn, and want to just dive into the programming side, then you could focus on simulation entirely. In that case, look into MuJoCo or OpenAI Gym (ported and maintained by community as ‘Gymnasium’).

Don’t be afraid to ask LLMs to help you learn. They might lie to you or occasionally send you down a non-optimal path, but they’ll be helpful first exposing you to so many of your current blind spots and helping understand the scope of any endeavor you might be interested in.

If you do decide to really invest in learning the electrical and mechanical sides, it can be worthwhile to truly learn them. This would involve following something like MIT’s open courseware (or similar) for electrical and mechanical engineering. You can get away without formally teaching yourself these, but it would unlock “real” engineering. Multivariate calculus is possibly enough for the mechanical side, but for electrical you’d also want to understand how to utilize differential equations. So in total, somewhere between the equivalent of 2-4 semesters of calculus. Linear algebra can help as well, but plenty of people without these math skills make really cool stuff in robotics.

You wouldn’t necessarily need to do the calculus and differential equations by hand like we did in University - as long as you can set up, manipulate, and solve the problems using computer software (numerically, maybe some symbolic manipulation) that would be enough for the hobby.

For enjoying robotics “as a consumer” (rather than as a do-er) there are some fun YT channels, which could either inspire you or scratch the itch passively just enough to rob you of the initiative to actually do it yourself:

Stuff Made Here

Mike Shake

Allen Pan

Michael Reeves

I did a thing

CodeBullet (towards the pure simulation side. this channel helps me when I’m feeling like a poorly educated useless engineer because it shows me that even the absolute lowest effort, dumbest approaches and worst execution can produce something both fun and rewarding. That can help me get out of ruts sometimes)

AlphaPhoenix (absolutely next-level explainers and demos of fundamental electromagnetic concepts and phenomena. The 3B1B of EM physics.)