ACCELEROMETERS |data acquisition systems|data logger|digital panel meter|vibration monitoring Accelerometers consist of a micro machined silicon mass suspendedby mulitple beams from a silicon frame. Piezoresistors located in the beams change their resistance as the motion of the suspended mass changes the strain in the beams. Silicon caps on the top and bottom of the accelerometers are added to provide over-range stops. Th accelerometer design provides for a low profile, high shock resistance, durability and built-in damping over a wide usable bandwidth. Schaevitz servo accelerometers are DC operated closed-loop force balance trandsducers for the masurement of acceleration. They are more stable and accurate than open-loop accelerometers by several orders of magnitude. Undesirable characteristics inherent in open-loop accelerometers such as sensitivity to supply voltage, non-linearity in the acceleration-to-position pickoff, and high thermal coefficients of scale factor and zero shift are neglible in closed-loop force balance accelrometers. Schaevitz servo accelerometers are closed-loop torque balance systems. A pendulous mass develops a torque proportional to the product of its mass unbalance and the applied acceleration. Motion of the mass is detected by a position sensor whose output signal is applied to an electronic amplifier. The output current from the servo amplifier is applied to a torque motor, which then develops a torque equal but directly opposed to the inital torque of the pendulous mass. Thus the mass stops moving, assuming a position minutely differing from its original position before acceleration. The current through the torque motor is accuratley proportional to input acceleration, and then passed through a stable resistor, an accurately proportional output voltage is developed. JEWELL LCM accelerometers are general-purpose acceleration sensors for industrial, commercial and aerospace applications. Engineered with micromachined components the LCM offers attractive price/performance ratio. This 0.5G to 4G device meets the demanding needs of applications requiring 500G shock resistance and up to 500Hz bandwidth. |
