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This paper describes a novel self-temperature-sensing method and temperature compensation of a quartz resonator force sensor based on dual-harmonic-mode oscillation. An AT-cut resonator, used as a force sensing element, is excited at the fundamental and the third overtone modes simultaneously by a specially designed oscillator. The beat frequency between three times the fundamental mode frequency and the third overtone mode frequency is linear with temperature and independent of the unknown force. Consequently, the temperature and force can be obtained simultaneously by the beat frequency and the third overtone mode frequency, respectively. As compared with conventional temperature compensation using a thermistor as a separate temperature sensor, the novel method can eliminate the temperature measurement error induced by the difference in the thermal time constants and the temperature gradient between the quartz resonator and the thermistor. The implementation of the dual-mode oscillating circuit is described, as well as a special method to reduce the frequency-temperature anomalies. The experimental results show that, in a dynamic temperature environment, the measurement error of the force sensor using the self-temperature-sensing method decreases by 80% as compared with the method using a separate temperature sensor.
Wang et al. (Thu,) studied this question.