Static force measurement for automation assembly systems

The paper presents a static force measurement based on the characteristic of piezoelectric devices which are known as an electromechanical transducer. Material properties of a piezoelectric device vary with applied static forces and merge into the equivalent electrical admittance of the piezoelectric device through the electromechanical interaction such that the applied static force can be obtained by the equivalent electrical admittance variation. Differing from the general static force measurement by piezoelectric devices, we measure the static force by detecting magnitude and phase of the admittance at a fixed frequency. A prototype for achieving the static force measurement is built as a cantilever beam structure. Experiments are carried out for evaluating the performance of two detection methods, results of which show that the repeatability and hysteresis error are less than 12.0% of full scale output (FSO) and 7.5% FSO, respectively, by using the phase detection method. The proposed static force measurement can be embedded in automation assembly systems due to its simple structure, which is particularly suitable for use of gripping jaw applications.

Measure static force by detecting admittance of piezoelectric material.
► Admittance is measured at a fixed frequency.
► Static force can be measured by magnitude and phase of admittance.