>Please explain why you're against steppers? I do value your thoughts and I want to learn
You are right they have some uses (where the inertia can be hidden/compensated like with or where the mass is not an issue like in medical manipulators, for example), but specific power is too low. As motors I like them and I have used them, but they are not up to the task I envision.
... Also there is no walking robot I have seen where the steppers were used in leg actuators. And that sums it up. High-performance arms are hard as well, and I don't see how you could use a stepper unless you have a very specific design where its mass isn't being lifted by the other motors (including legs).
>Feels like a decade since I last researched the HRP-4 platform. Impressive for the time, it still relies on brute force to overcome it ineficient design.
While I agree that japanese robots tend to be static and relatively inefficient compared to boston dynamics' singular designs (comprising a class of their own tbh, being built by very bright and degreed engineers passionate about the idea - very hard to compete with), HRP4-C is notably more lightweight than its predecessors. It's a honest attempt at building a real humanoid robots by smart educated asian engineers.
Yes, low-power dynamic walk is a possibility, though it's nonlinear and hard. With these nonlinear features you have to co-design the whole humanoid mechanism around it so that at any point of the intended functionality space you don't destroy the possibility of the nonlinear phenomena you need working.
Nice design, feels almost like a mujoco model tbh, we should try implementing it and trying RL controller on it.
>What rods are recommended by the team
RC hobby carbon rods, or glass fiber, or a good wood would fit. Wood is good enough.
I like rocker-bogie for mobility, though the bearings and associated servos may be too hard to control, removing much of the benefit of a mobile base KISS-wise.
Overall, my position is simple: once you can make a semi-decent servo from a hobby BLDC, you have the hardest part of the robot ARM. The rest is design and 3D-printing, or appropriating existing hand designs (e.g. http://inmoov.fr/build-yours/hand-and-forarm-assembly-3d-views/
). Once you have a robot arm, you have the hardest part of a wheeled mobile robot (the other hard part being power electronics for managing autonomy and power supply though).
Thus we need to focus on a servo, or a stepper for that matter (if we are going to build a heavy slow arm, which is better than none).
Maybe you could create a webpage on neocities.org with a realistic bullet list of features for a given year, and BTC/ETH/XMR addresses for the kind souls to donate. If we made a decent simulation and showed it to enough people, surely some would donate some money for you to buy BLDCs and other gear.
1. PR2 robot (heavy & obsolete, notably uses mechanical gravity compensation in its heavy arms) https://www.clearpathrobotics.com/assets/downloads/pr2/pr2_manual_r321.pdf