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resources:eval:user-guides:inertial-mems:imu-overview [22 Jul 2021 15:34] – [Angular Random Walk (ARW)] Chas Frick | resources:eval:user-guides:inertial-mems:imu-overview [31 Aug 2021 22:00] (current) – [Linear Acceleration Effect (Linear-g), Linear Acceleration Effect on Bias, Linear-g Rejection (Linear-g Sensitivity)] Chas Frick | ||
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This can be thought of as the sensor resolution in an "ideal case." It is also found as the minimum of the AVAR plot. | This can be thought of as the sensor resolution in an "ideal case." It is also found as the minimum of the AVAR plot. | ||
- | ====== | + | ====== |
Measured in °/ | Measured in °/ | ||
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For an example consider the ADIS16153, with datasheet here: [[adi> | For an example consider the ADIS16153, with datasheet here: [[adi> | ||
{{ : | {{ : | ||
- | So here the AllanVariance is 0.1°/sec at Τ=1 (sec). Converted to hours, this is 0.1 * 3600 = 360°/hr. Then divide by 60 gives 60 °/ | + | |
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- | ====== | + | ====== Rate Random Walk (ARRW) ====== |
Applies to gyroscopes and is the "far out" (large Τ) on the Allan Variance (AVAR) curve. | Applies to gyroscopes and is the "far out" (large Τ) on the Allan Variance (AVAR) curve. | ||
This quantity represents long-term stability of the sensor measurement. | This quantity represents long-term stability of the sensor measurement. | ||
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Can be approximated with the formula: ND ≅ ARW/60* √2 | Can be approximated with the formula: ND ≅ ARW/60* √2 | ||
- | ====== Linear Acceleration Effect (Linear-g) ====== | ||
- | Measured in degrees/ | ||
====== Vibration Rectification Error (VRE) ====== | ====== Vibration Rectification Error (VRE) ====== | ||
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====== Cross-Axis Sensitivity ====== | ====== Cross-Axis Sensitivity ====== | ||
- | Unintended effect where rotation/ | + | Unintended effect where rotation/ |
+ | Can be calculated from axis to axis misalignment error for accels/ | ||
+ | |||
+ | Example: For the ADIS16448, the accel axis to axis misalignment is 0.2 degrees. Therefore Cross-axis sensitivity accel is sin(0.2) = 0.197%. Gyro is sin(0.05) = 0.09%. Magnetometer: | ||
+ | |||
+ | ====== Linear Acceleration Effect (Linear-g), Linear Acceleration Effect on Bias, Linear-g Rejection (Linear-g Sensitivity) ====== | ||
+ | Unintended effect where linear acceleration is detected as rotation. Measured in degrees/ | ||
+ | |||
+ | ====== Vibration Rejection (Gyros) ====== | ||
+ | A combination of Linear-g and Vibration Rectification (VRE) specs. | ||
+ | |||
+ | Vibration response of a gyro = Linear-g X-Axis Acceleration + (VRE X-Axis Acceleration)^2 | ||
- | ====== | + | ====== |
- | Unintended effect where linear acceleration is detected as rotation | + | * Information on Allan Variance for Gyros: http:// |