Measuring nightly activity, body weight and body weight change rate with a sensor equipped bed

A bed was equipped with four force transducers so that the location of the Center Of Mass (COM) can be computed, when the bed contains a person. The computation of the COM and its alterations in combination with the sum of all measured forces allows to compute the person´s position in bed, an activity level, the resulting body weight and the corresponding weight change rate over time (overnight and long-term) as well as simply to determine whether the person is in the bed or not. The results of several overnight measurement experiments show, that the person´s position in the bed (central, left, right) can be correctly detected, the proposed activity level is a promising indicator for the sleep-activity and furthermore the initial body weight as well as the nightly weight change rate can be determined.