• IEEE P1451.3 A Developing Standard For Networked Transducers

      Eccles, Lee H.; Boeing Commercial Airplane Company (International Foundation for Telemetering, 2001-10)
      The IEEE P1451.3 standard for networked transducers is designed to support applications in many industries but aerospace representatives have had a major say in what is included in the standard. The standard is written to allow multiple different transducers to exist on a single transmission line. This single transmission line may also carry power to the transducers. A bus is expected to have a single controller and many transducers. Individual transducers may be operated in several modes including a strict master-slave relationship or individual transducers may operate independently from the bus controller. In addition the bus controller can provide a clock to allow all transducers to operate synchronously or the clock can be ignored for asynchronous operation. The standard includes an extensible command set and Transducer Electronic Data Sheets (TEDS) that allows for full plug and play operation of the transducer. If a manufacturer chooses to leave out some of the features that allow for plug and play operation the standard allows for that as well. This paper provides an overview of the features of the standard as well as the types of system that can best utilize these features.
    • PRESSURE BELT FOR WING LOADS MEASUREMENT

      Eccles, Lee H.; Boeing Commercial Airplane Company (International Foundation for Telemetering, 2001-10)
      Boeing Commercial Airplanes has used many methods in the past to measure the structural loads on the wings of its airplanes. The most recent approach is to use arrays of MEMS pressure sensors on the top and bottom surfaces of the wings. By knowing the difference in pressure between the top and bottom of the wings the structural loads on the wings can be calculated. It was decided that in order to build an array of 1100 sensors it would be necessary to condition the sensors and convert the analog output to a digital form at the site of the pressure measurement. This process was taken one step further by converting the output of the A/D converter into engineering units within the sensor module as well. The array is built using a flex circuit card in one foot sections that can be interconnected to form an array of up to 125 sensors. There is a sensor location every two inches on the flex circuit but not all locations are populated. This paper will describe not only the pressure belt but the lessons learned during the development and the implications that these lessons have for smart transducers in general.