US Patent 7640826 Actuator apparatus incorporating a controller

An adjustable positioning apparatus, which may be used for a foot-operated control, includes a first member that is movably supported with respect to a base, an adjuster that is supported on the first member, and a second member. The adjuster includes a displacement device, an actuator, and a controller. The displacement device includes a first portion that is coupled to the first member, and includes a second portion that is displaced with respect to the first portion. The actuator displaces the second portion with respect to the first portion, and the controller operates the actuator and determines displacement of the second portion with respect to the first portion. The second member is coupled to the second portion.