20 years ago this year ASIMO 2004 launched and is still seemingly state of the art. Why did it fail? 🧵The Bandwidth Dilemma: Understanding Human Biomechanics to Build Better Robots

Animals are masters of adaptability and compliance. We are purpose-built to move fast with minimum energy so we can collide safely. All we do is collisions, picking up a cup, taking a step, grabbing that door handle, and we are not fast enough to react to sense of touch and stop

Kinetic Energy is 1/2*(m*v^2+I*w^2). Notice the velocities are squared. That's why, in nature, nothing ever moves faster than it has to. ASIMO has motors with 100:1 reducers, rotating 100x the joint speeds, that's 10.000 times the energy. Think of a big flywheel spinning up

So when ASIMO is running, we can compute the rough equivalent inertia of the spinning flywheel to its foot. It works out to about 20kg. So it's running around with a 20kg kettlebell strapped to each foot (why robots walk weird and are unsafe) and roughly 10kg to each hand.

@BerntBornich This is a strange take. The issue isn’t stored energy, the problem is that motor power density can’t stop the gear box. Better designed brushless motors mean more actuation power density, improved batteries can deliver much higher currents, which means better dynamic control.

@BerntBornich Ok, but you are building a humanoid. So moving “passive” weight off the arm just means it’s getting moved to the body. That inertia still loads the walking dynamics. I think Asimo could be rebuilt today with modern brushless actuator instantiations (custom) and be effective.