Patent ID: 7832711

Claim:
A control system for controlling rotation of a servomotor to vertically move a load supported by a flexible support device, the control system comprising: a single sensor for: measuring a force acting on the support device, the force comprising the sum of: a force caused by a mass of the load; a force caused by an acceleration of the load; and an externally-supplied user force; and outputting a load signal corresponding to the measured force; and control means for supplying to the servomotor, based on the load signal and a control algorithm, a servomotor drive signal specifying servomotor operating parameters, including a rotational direction and a velocity, sufficient to cause the servomotor to impart to the load via the support device a desired elevating velocity within a desired amount of time; wherein the control algorithm is expressed as K f =k p ω n 2 /( s 2 +2ζω n s+ω n 2 ), where: k p is a transformation coefficient [(m/s/N)], ω n is a natural angular frequency [rad/sec], s is a Laplacian operator [1/sec], and ζ is a damping coefficient.