A High-Precision Position Turn-Table as the Reference for Angular Accelerometer Calibration Experiment
Calibration tables commonly known as turn tables are widely used to produce motion input to excite inertial sensors. Its mounting platform’s orientation can be single-axis, or two to three axis degree-of-freedoms. The measurements from the turn-tables-generated motion have been applied not only to different types of inertial sensors such as linear accelerometers and gyroscopes, but also for groups of sensors in for instance Inertial Measurement Units (IMU). The calibration table (CT) operated by Control and Simulation Section, Faculty of Aerospace Engineering – TU Delft, is a high-precision position turn-table, which means it provides the angular displacement measurement. In addition, the CT controller computes and processes the angular velocity from the measured data, since it is used in the control feedback loop. However, the calculated angular acceleration data contains noise as a result of the double differentiation, hence needs further processing to be used as a valid reference in angular accelerometer (AA) calibration. The CT and sensor data acquisition systems (DAS) are different independent units, which produces additional issues in the data post-processing. For example, the nominal table’s sampling frequency of 2 kHz only allows for a division by an integer, which will require a resampling process for sensors with a fixed sampling frequency that does not match the 2 kHz. With regards to the data recording, both DAS have their own start and stop command logic which leads to unsynchronized results. This paper identifies the CT – AA systems issues that affect the sensor calibration experiments, as well as the possible solution on how to carry out the AA calibration experiment. The CT system consists of two subsystems: the controller and the turn table, whereas AA included two subsystems: the sensor and its DAS. The discussions are limited to motion, sensing and data collection in the experiment without the electrical and mechanical properties of the CT servo and actuator system.