Overview

The FAST parameter group (specifically FAST_SAMPLE) controls high-rate hardware oversampling for IMU Sensors.

Key Concepts

1. IMU Fast Sampling

Modern IMU chips (InvenSense, Bosch) can sample data at multi-kHz rates internally. By enabling fast sampling, the autopilot's CPU pulls data as fast as the SPI bus allows (e.g., 8kHz or 16kHz) and performs a low-pass filter in software before down-sampling to the main loop rate (e.g., 400Hz).

• Benefit: Dramatically improves noise rejection and reduces "aliasing" (where high-frequency vibration looks like low-frequency control problems).

Parameter Breakdown

• FAST_SAMPLE: Bitmask to enable fast sampling for specific IMUs.
  • Bit 0: IMU 1.
  • Bit 1: IMU 2.

Developer Notes

• Library: libraries/AP_InertialSensor
• Hardware: Requires high-performance processors (F7, H7) and sensors capable of high-speed SPI (ICM-20602, ICM-42688).
• Alias: INS_FAST_SAMPLE.