Design of intelligent bearing vibration monitor

Critical issues in the design of an intelligent sensor for monitoring bearing vibrations are discussed. The device couples a microaccelerometer with a half-active piezoresistive bridge, a second-order oversampling sigma-delta analog-to-digital converter, digital filters, logic for extracting mean squared signal values, and communication circuitry. The sensor is semiautonomous and serves as a component in a plantwide monitoring system. It can operate in monitor mode with user programmable filter coefficients, mean squared vibration threshold level and number of threshold exceptions before warning, or in accelerometer mode with up to a 14-b digital output. The design is compatible with BiCMOS circuitry and processing. Simulation results obtained with a multiple module simulator written in C are presented