LOCATION OF FORCE IMPACT BY INDICATOR PIEZOELECTRIC MDS COATING BASED ON INFORMATIVE VOLTAGE PULSES

An electromechanical mathematical model is developed to locate a single force effect of pressing a rigid ball particle into the sensor surface of an indicator piezoelectric MDS coating with an integrated double spiral of electrodes. We consider formation of informative voltage pulses on arcs of electrodes of a double spiral in a circular perturbation zone of an indicator coating due to piezoelectric deformation between the electrodes when pressing a rigid ball particle. Shape and duration of informative voltage pulses as functions of time are found by solving the corresponding differential equation taking into account piezoelectric and geometric characteristics, value, nonuniformity, duration and distance from the epicentre of the electrode/piezoelectric/electrode disturbance arcs acting on each of the piezocells within the circular disturbance zone of the indicator coating. The number of pulses generated and recorded is proportional to the ratio of the perturbation zone radius and the sensor spiral pitch of the indicator coating. Here the perturbation zone radius is proportional to the diagnosed force. A simple, convenient and applicable solution of location is obtained, i.e. finding polar coordinates of the epicentre of the force effect, while the accuracy of the location improves when the number of the spiral turns increases, i.e. the pitch of the sensor spiral decreases, relative to the radius of the perturbation zone.