A low-cost diagnostic tool for stepping motors

This paper presents a low-cost diagnostic tool to point out if anomalous no-motion condition occurs when stepping motors are used in tool-machine industrial applications. The method is based on current sensing: by evaluating the second derivative of the current in the windings just switched on, it is possible to understand if motion takes place. The proposed method has been implemented using a 16-bit microcontroller. Since this diagnostic tool is based mainly on the infernal resources of the microcontroller and takes about 40% of the total computation time, if could be integrated into the digital motor drive. Experimental results show that under heavy-load working conditions about 90% of the anomalous waveforms are detected, while spurious inopportune not filtered alarms are negligible (0.001% measured with respect to over half a million of analyzed waveforms)