US Patent 7810791 Hoist controls with compensation for dynamic effects

A servo motor driven hoist includes a float mode in which a load is raised lowered in response to manually applied forces on the load exerted by an operator in which forces applied to the load as a result of accelerations of the load generated by hoist movement of said load are compensated for by sensing the accelerations and computing the forces resulting therefrom, and subtracting those forces from the sensed total magnitude of forces acting on the load to eliminate the effects of dynamically generated forces when in the float mode.