If you want to train control software for a delicate humanoid hand, why not scale it up two or three times to get robustness, and then have it manipulate equivalently enlarged test objects?
I suppose there might be some square-cube law stuff when it comes to catching and throwing...
The mass being different, this leads to different forces required to get the same acceleration or deceleration. That follows directly from the formula: force = mass * acceleration.
Moreover, the resonance frequency [1] of an object is different for different scales. For example, piano strings will vibrate at different speeds, depending on their sizes. That would be the same for the robot cables.
Also, when changing the scale of an object, the materials often change. The cables and the motors would probably be built differently, with different physical properties.
In general, to design a new mechanism, it is common practice to start with software simulations, 3D prints, and small scale prototypes. However, the properties of the new mechanism are only validated when you have built a real size prototype.
> You're trying to predict the behavior of <complicated system>? Just model it as a <simple object>, and then add some secondary terms to account for <complications I just thought of>
> Physicist: Easy, right?
> Physicist: So, why does <your field> need a whole journal, anyway?
> Liberal-arts majors may be annoying sometimes, but there's nothing more obnoxious than a physicist first encountering a new subject.
Yes, physical scale absolutely matters. I'm a controls engineer in industrial robotics. Some of my material handling projects involve giant Fanuc R-2000 robots that move very much like gigantic, dextrous fingers as they use incredible levels of power with their rigid gearboxes and heavy castings to manipulate payloads weighing hundred-kilogram payloads. They're fast for what they are, but they move with all the urgency of a barge compared to human fingers. They're completely different from tiny high-speed conveyor systems using little SMAC linear motors and laser galvos that are flapping about at speeds the eye cannot hope to track.
There is square-cube law stuff everywhere. Also, power density, strength-to-weight ratios, and stiffness of actuators and limbs has enormous variance - your intuition about what a mechanical gripper might do or how rigid a finger vs. a block of steel might be will likely mislead you.