Anyone tried a group-funded open hardware harmonic drive project?

[matthew43]

@servobre20 Just to be precise about one thing: Building a scoped-down project first - a single leg, an arm, or a torso-only upper body - is a common and sensible way to learn the mechanical and control fundamentals before committing to the cost and complexity of a full bipedal platform. The Berkeley Humanoid Lite stands about 1 meter tall and weighs roughly 16 kg, which is a genuinely reasonable target size for a first serious hobbyist build - big enough to be a real bipedal platform, small enough to not need industrial-scale actuators or a huge budget.

[jhansen]

@matthew43 I'd push back on this a bit. Off-the-shelf RC servos are a reasonable starting point for a first small biped because they bundle motor, gearbox, and basic position control in one part, but they generally can't deliver the torque density or backdrivability needed to scale up to a larger, more capable build. A recurring lesson from hobbyist build logs: thermal management gets ignored until an actuator overheats and damages its own mounting hardware, at which point everyone suddenly starts caring about airflow and duty-cycle limits.

[sarah.santos3]

@jhansen Slight correction, though the overall point stands: Building a scoped-down project first - a single leg, an arm, or a torso-only upper body - is a common and sensible way to learn the mechanical and control fundamentals before committing to the cost and complexity of a full bipedal platform. Joining an existing robotics community (FRC, university clubs, maker spaces) before going fully solo is a common and effective way to pick up practical fabrication and control skills faster than working entirely alone from tutorials. Makes me wonder how this looks in another five years.

[joseph.robinson]

Ran into exactly this myself. A first successful unassisted walk, from a standing start on a from-scratch project, commonly takes many months of part-time weekend work even for someone with a solid mechanical and software background - it's a genuinely hard milestone, not a weekend project. Reminds me a bit of the early drone hobbyist scene, honestly.

[karen.chen3]

Yeah, this tracks with what I've read as well. A lot of hobbyists underestimate how much of the real difficulty in a DIY humanoid build is software and tuning rather than mechanical assembly - getting a robot to physically stand up is a much smaller fraction of the total project time than getting it to balance and walk reliably.

[kwameivanov]

@karen.chen3 Related question - Building a scoped-down project first - a single leg, an arm, or a torso-only upper body - is a common and sensible way to learn the mechanical and control fundamentals before committing to the cost and complexity of a full bipedal platform.

[byang]

@kwameivanov Not to derail, but this reminds me of something adjacent: Starting in simulation (even a simplified physics sim of just the leg or the target gait) before touching real hardware is one of the more reliable ways to avoid destroying expensive parts while debugging balance and walking control from scratch.