alt Hacker NewsThe force an impulse generates on a contact depends on the speed of deceleration. It's just F=m*a
Slow deceleration leads to low forces. If you have a contact event with a hard substance, like a rigid metal for accurate kinematics, the deceleration to zero upon a contact has to happen instantly. Meaning the deceleration is incredibly high, resulting in extremely high forces for a few milliseconds.
Human bodies are made out of a flexible and impact resistant material: water. When a contact event happens, your body deforms, which means that the deceleration happens over a longer time frame with less force. Not just that, your muscles also have a certain amount of flexibility in them and basically zero internal inertia. All the inertia is in the limb as a whole, whereas for a robot there is a spinning motor and gearbox that needs to slow down as well.
You could solve this as a control problem by adding series elastic actuators, which means you need to change your mechanical design.
The human body goes further than that too, when you're out jogging - as your foot approaches the ground for a stride, you slow the velocity of your foot downwards towards the ground so there's less of a sudden deceleration.
Imagine when you throw a tennis ball high in the sky, and then you catch it on your racket without bouncing by matching it's velocity, your feet do the same thing with the ground on a smaller scale.