Delco Electronics Corporation

Jack Daniel Johnson

Michael Ik-Ming Chia

Carl David Wright

Seyed R Zarabadi

Fie A Liem

Michael William Putty

A motion sensor having a micromachine sensing element and electrodes formed on a silicon chip. The sensing element includes a ring supported above a substrate so as to have an axis of rotation normal to the substrate. Surrounding the ring is at least one pair of diametrically-opposed electrode structures. The sensing ring and electrode structures are configured to include interdigitized members whose relative placement to each other enables at least partial cancellation of the effect of differential thermal expansion of the ring and electrodes. As a result, the performance of the motion sensor is, to first order, insensitive to temperature variation. The sensor further includes circuitry for creating and detecting an electrostatic force between the interdigitized members of the sensing ring and electrode structures. The circuitry operates to sum the electrostatic forces such that, on the occurrence of a temperature change, a corresponding decrease in the electrostatic force between one pair of interdigitized members will at least partially cancel a corresponding increase in electrostatic force between a second pair of interdigitized members. Accordingly, the net effect is that a temperature change will have a reduced effect on the sensing performance of the sensor, because the effects of thermal expansion will be at least partially canceled.

Temperature-compensated surface micromachined angular rate sensor

A yaw sensor for automotive controls has a microstructure vibrating ring excited by a driving circuit. The driving circuit comprises an amplitude control loop which delivers voltage pulses at the resonant frequency of the ring. A compensation signal is derived from a comparison of a sensed vibration amplitude to a desired vibration amplitude. Failure of vibration is detected by comparing the compensation signal to a threshold which is higher than a normal compensation signal. Alternatively, vibration failure is detected by comparing the sensed vibration to a threshold lower than the desired vibration amplitude. Upon such failure, the yaw output signal is replaced by ground potential.

Method and apparatus for detecting failure in vibrating sensors

A yaw rate sensor having a vibrating ring microstructure surrounded by electrodes capacitively coupled to the ring has vibration responsive circuits with inputs connected to several of the sensors, the circuits having outputs connected to others of the electrodes for driving or influencing the vibration. The circuits produce a main drive voltage to excite the ring to resonance, a feedback drive voltage to provide force-to-rebalance correction, and a dc compensation voltage to tune the ring to a single resonance frequency. An economy of electrode space is achieved by using some electrodes for more than one function, e.g. feedback and compensation.

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Rossville, IN, United States of America

Jack Daniel Johnson