A person support apparatus, such as a bed, cot, stretcher, or the like, includes an exit detection system that utilizes an occupant motion parameter to determine whether to issue an alert or not. The motion parameter may be based on the weight and motion of the occupant. Successive positions of the occupant are determined in order to calculate a velocity of the occupant. In some embodiments, the kinetic energy of the occupant is used to determine if an alert should be issued. Objects positioned on the person support apparatus may also be detected and tracked. Auto-zeroing of a built-in scale, as well as automatic recognition of the removal, movement, and/or addition of objects is also provided.
