Inertial Instruments Tests Technology On Dual-axis Centrifuge

As the primary inertial measurement devices, accelerometer and gyro determinethe precision level of navigation basically. So the precise calibration of accelerometerand gyroscope, has an important theoretical and practice significance for improving theaccuracy of them in its use.In this paper, some new calibration methods, which can be applied toaccelerometers, gyroscopes and inertial system, were proposed, in the background ofthe application of precision centrifuge. That is, some new discussions were given for thecalibration of a single inertial and system-level calibration of inertial system.The characteristics of the two-axis centrifuge were described at first. A ramp fixturewas designed and fixed on the counter-rotating platform to ensure the three axesof accelerometer to sense components of the harmonic acceleration and the accelerationof gravity. The centripetal acceleration, the acceleration of gravity, theCoriolis acceleration and the errors of the two-axis centrifuge were analyzedto accurately calculate the input specific force of three axes of accelerometer.For calibration of the accelerometer static error model, First, the averagevalue of the accelerometer outputs, which are from the static tests when the spindle axisrotated to equal-spaced angular positions and the axis of counter-rotatingplatform reversed to equal corresponding positions, was achieved. Average valueof the static test in vibration rectification experiments was compensated for, wherespindle axis rotated with constant angular rate and the platform axis rotated in theopposite direction with the same rate, accelerometer error modelcoefficients were identified finally. The relationships between calibration accuracy oferror model coefficients and errors of the centrifuge were deduced. The test simulationresults show that centrifuge errors are suppressed greatly when adopting dual-axiscentrifuge, and the effect of dynamic misalignment angle of counter-rotating platformcan not be ignored. The measurement accuracy ofthe centrifuge’s dynamic misalignment error should be raised. And some analyses andcompares about advantages and disadvantages between the harmonic analysis methodand vibration rectification method were analyzed.The centrifuge error, earth’s rotation angular velocity were analyzed to accurately calculate the input specific force and angular velocity of three axes of gyro. Similarly,harmonic analysis and vibration rectification method were analyzed and compared inthis experiment, where spindle axis rotated with constant angular rate and theplatform axis rotated in the opposite direction with the same rate. Then some simulationtests were given to analyze advantages and disadvantages of these two methods.Finally methods about system-level calibration on the dual-axis centrifuge werediscussed. Since the rotation of the centrifuge, SINS system were the moving basesystem. Using centrifuge spindle rotation to provide high-g input specific forces,precise angular velocity and speed, the output of navigation system could be obtained.Then, compared with the given centrifuge speed information, the speed error could begot. And then, the speed error equation could be set up. According to the system errormodel equation, which was associated with speed error model equation, the maximumquantity of errors in the model parameters could be derived. Combined with thecharacteristics of speed given by centrifuge, the error characteristics of the modelequations could be gained. Then the full circle rotation test method, proposed in thispaper, which gave out the results that using this method we could calibrate14errormodel parameters and the reasons for not calibrating others during the test, wasdescribed in detail. All of these have laid a certain foundation for further and in-depthresearch work.