Integrated Static Load Measurement Using a Piezoelectric Sensor
Robert X. Gao, Ph.D.
A new technique that measures static load applied to a mechanical structure, by using a piezoelectric load sensor. Major elements include electronic circuitry that integrates the electrical charge signal generated by the sensor when subjected to a static load, converts it to a digital code and stores its peak value, which corresponds to the peak value of the load. Measurement accuracy is ensured by utilizing a feedback technique to compensate for the signal loss due to charge leakage. A software code embedded in a microcontroller controls the entire measurement and data display process.
Such machine-integrated load monitors can over-see an entire machine system or process, and improve overall efficiency and safety. Bearing manufacturers and other end users have strong interests in knowing the static load applied to a machine during operation, and this invention should be of use to a wide range of industries, such as automotive, paper and pulp, trans-portation, industrial processes, and machine tools. Useful in monitoring threshold weights for safety applications, such as in fork lifts or stationary loads in storage.
The piezoelectric sensor does not require a power supply to function, as opposed to widely used strain gauge sensors for static load measurement. The new technique is capable of measuring static loads in quasi real-time fashion, and uses a feedback technique to compensate for signal loss due to charge leakage, therefore ensuring measurement accuracy. It provides a "zero line" as the reference base for absolute load reading.The system can be miniaturized and integrated into a machine component and not compromise the machine system itself. This technique is essential to realizing the next generation of "smart" machine components that can self-diagnose working conditions, and address condition monitoring of mechanical systems and manufacturing processes, thus, reducing down-time and improving productivity. This invention can introduce a new means to the next generation of intelligent machines and can advance safety in industrial operations.
US Patent 7,104,139 Issued
Commercial Ventures and Intellectual Property