Application of a Passive Magnetic Suspension to a Floated Pendulum Accelerometer

In the last few years, in order to develop more precise inertial sensors such as floated gyros and floated accelerometers which will be used in the inertial navigation system, a passive magnetic suspension with an eight-pole stator, which can be applied to supporting the output axes of the sensors, had been theoretically and experimentally studied at NAL. Those were described in the first report and the second. This study is an application of the passive magnetic suspension to a floated pendulum accelerometer. This repart describes the principle of the magnetically suspended accelerometer, the design of the magnetic suspension, the design of the torque generator and of the signal generator, the performances within ± 1 G region of the accelerometer, the characteristic of the magnetic suspension. The performances of the new accelerometer are as follow; measuring range ± 15 G, resolution 3.3 × 10-7 G, non-linearity coefficient 3. 4 × 10-5 G/G2, repeatability (short term stability) × 5.6 × 10-6 G. These performances are compared with that of the former floated pendulum accelerometer without the magnetic suspension which was developed at NAL. With respect to the resolution and the repeatability, each of the above mentioned accelerometer value is less than about one hundredth as compared with the former accelerometer value.