A human power amplifier includes an end-effector that is grasped by a human operator
and applied to a load. The end-effector is suspended, via a line, from a take-up
pulley, winch, or drum that is driven by an actuator to lift or lower the load.
The end-effector includes a force sensor that measures the vertical force imposed
on the end-effector by the operator and delivers a signal to a controller. The
controller and actuator are structured in such a way that a predetermined percentage
of the force necessary to lift or lower the load is applied by the actuator, with
the remaining force being supplied by the operator. The load thus feels lighter
to the operator, but the operator does not lose the sense of lifting against both
the gravitation and inertial forces originating in the load.
