Static Accelerometer Orientation Tumble Calibration Procedures
Static tumble calibration calculates accelerometer bias, scale factor, and cross-axis matrices by optimizing spatial vector residuals against local gravity.
Tilt Sensitivity
Angular Response
Transducer output variations that occur when a sensor is inclined relative to the direction of gravity define its responsiveness to angular positioning. For an accelerometer, tilt sensitivity represents the change in measured acceleration per degree of inclination from the horizontal plane. This sensitivity follows a sinusoidal relationship based on the angle of inclination.
The response is used to measure inclination in electronic levels and platform stabilization systems.
Bias Drift
External tilt of the sensor platform can introduce unwanted gravity coupling that resembles a drift in the sensor bias. In gyroscopes, tilt sensitivity can cause the output to shift because the gravity vector acts on the internal sensing structure. This cross-coupling error must be identified and corrected to maintain navigation accuracy in moving vehicles.
The error is modeled as a g-dependent bias offset in the sensor output equations.
Calibration Assessment
Verification of the tilt response is performed by rotating the sensor through a known angular sweep using a precision dividing head. To characterize tilt sensitivity, the sensor is mounted on a stage that has been aligned with the local gravity vector. The angular sweep is executed in small increments to map the sensor response and detect any non-linearities or hysteresis.
The collected data is used to verify the calibration parameters across the operational tilt range. If the response deviates from the expected curve, the sensor is flagged for recalibration. This verification ensures the sensor meets its angular accuracy specifications.
Mechanical Mounting
Rigidity of the sensor mount on the system board is necessary to prevent parasitic tilt during operation. If the board deforms under thermal stress, the resulting tilt sensitivity will introduce errors into the sensor readings. This issue is resolved by using strain-relieved mounting structures that isolate the sensor package from board bending.