Dynamic position locating system

摘要

A position locating system for calculating the coordinates of a localized force applied to a surface (101a) has force sensing devices (101, 501, or 501a) for supporting the surface (101a). The force sensing devices provide force proportional electrical signals to a processing system (512) for calculating the position of the localized force applied to the surface. In order to provide samples of the dynamic alternating current characteristics of the force proportional electrical signals to the processing system, the improvement comprises an alternating coupling circuit (508) associated with each force sensing device. The alternating current coupling circuit accentuates the common dynamic frequency characteristics of the variety of forces presented to the system. The sample collection circuit (511) of processing system (512) sequentially collects samples (401a) of the force proportional electric signal from each AC coupling circuit (508). The samples are collected either until a predetermined interval of time lapses (402) or until the second zero crossing (403) of one electrical signal sample is detected, whichever event occurs first. The calculating circuit ( 512a) of the processing system averages the samples before calculating the coordinates of the point of application of the localized force. The calculating circuit also automatically adapts to a changing environment by establishing an average reference level for each force sensing device during a quiescent state condition prior to the collection of force samples.