Off-axis loadcell force sensing to automatically determine location of specimen features

Abstract

The present disclosure relates to a method in materials testing to automatically locate the center of a feature on or in an object using the off-axis force feedback of a loadcell. In this disclosure, either a simplified model of the product or device being tested, or the product itself, is placed under the loadcell probe with the feature of interest roughly aligned under the probe tip. The probe is driven down into the feature. The product is automatically positioned relative to the probe in the x-direction until the side of the probe contacts the side of the feature. Contact is determined by monitoring the force feedback from the loadcell. When the vertical force from the side-load surpasses a pre-determined setpoint, contact is assumed and the value of the x-position of the product with respect to the probe is recorded. The product is then repositioned in the opposite direction in the x-axis to record the touch load on the other side. The center is then calculated as the average of the x values. The process is repeated along the y-axis. This data is then used to calculate the center of the feature and the product can be positioned at this location so that the probe is centered over the center thereof.