Here they come: Larger format BLDC Gearmotors

[Alan Timm]

We're finally starting to see manufacturers mass produce large(r) bldc gearmotors for robotics.  It would be fun to do the math to figure out how tall of a humanoid could be built with these.

https://robstride.com/products/robStride04

https://www.youtube.com/watch?v=gpPUUF1v5l4

https://x.com/sirwart/status/1811436338585158049

https://x.com/RobStride_com/status/1816770909039976521

$300, 120N.m, 9:1 reduction, 1.5kg, everything a larger robot needs to move about.

[Chris Albertson]

A quadruped needs 12 motors not counting the head.   So at $300 each this comes to $3,600.    A humanoid needs about 28 motors but the exact number depends if you want usable arms and hands or just simple walking on a flat floor.   So let’s say $9,000 for a humanoid that can do useful work.

And then you need so structure and a few computers and batteries.    Assuming you can do you own design and CNC machine work, the major just is the motors.

Humanoids really do requires large motors of this size but quadrupeds can be made smaller with motors costing half as much.

How large can the humanoid be given that the motors are 120 Newton Meters?  The answer depends on the task, does it need to be able to lift and cary objects and will it walk of flat floors or on common outdoor surfaces?     Also you might be able to double a few of the moters, running then in parallel to create 240 Nm torque for a knee and hip joint.

<robostride-04.jpg>

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<robostride-04.jpg>

[Subhobroto Sinha]

It feels like a lot of companies that build "personal assistance robots" (should we call them (robotic) butlers?) are going to enter the market over the next decade.

While this means that this would make available to us a set of readymade, fully developed robots, I worry that, perhaps purely out of liability reasons, they would be completely inaccessible for modifications. That would be a real loss - is there something we can proactively do, so that doesn't happen?

Some recommended giving "Right To Repair" more teeth, but I don't fundamentally buy it because I want to reprogram it - not just have the ability to repair a black box that I cannot reprogram

[Chris Albertson]

Modification is always possible. But it could be harder or easier. I doubt they will be fully open-source. I guess that they will be about as “modifiable” as a hoverboard. This means you are going to have to trace the PCB routes and find the programming pins on the microcontrollers that control the motors and then completely 100% replace the overall control computer. Basically you’d be re-using the basic hardware and doing the software from scratch.

But it will be a LONG time before anyone offers a useful personal assistance robot