Interfacing with a capacitance based strain sensor for use in CNC milling applications.

摘要

"Smart machining" provides feedback to the machine in an attempt to avoid pushing the cutting tool beyond its capability or lifetime, potentially ruining the tool or workpiece. This thesis details the process of designing a circuit board for communication with a capacitance-based wireless strain sensor to achieve a target strain resolution of 10muepsilon, at a target measurement rate of 100 kHz. The sensor resonates at a particular frequency, which varies as a function of strain on the tool. The strain is calculated as a function of the change in the resonant frequency. The results of this research are presented in terms of the effective sampling rate based on the number of samples to average in order to obtain a measurement, where based on the noise in the measurement, 280 samples must be averaged in order to obtain a strain measurement. These results demonstrate the successful concept of wireless strain measurement with a capacitance-based sensor.