BB.Estimator.Ahrs.Madgwick (bb_estimator_ahrs v0.1.0)

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Madgwick AHRS filter, 6-DOF IMU variant, implemented as a BB.Estimator.

Fuses gyroscope and accelerometer measurements into a drift-free orientation using a gradient-descent optimisation step. Consumes BB.Message.Sensor.Imu inputs and republishes them with :orientation replaced by the fused estimate; :angular_velocity and :linear_acceleration are passed through unchanged.

Usage

sensor :imu, BB.Sensor.SomeImu, ... do
  estimator :orientation, {BB.Estimator.Ahrs.Madgwick, beta: 0.1}
end

Options

  • :beta — gradient-descent step size. Higher = tracks faster but noisier. Default 0.1.
  • :accel_threshold — accepted deviation of |accel| / g from 1.0 before the accelerometer correction is suppressed (gyro integration only). Default 0.1 (i.e. ±10% of 1 g).

Ported from gworkman/ahrs' Ahrs.Madgwick.

Summary

Types

t()

Functions

orientation(madgwick)

Convenience: returns the current orientation as a BB.Math.Quaternion. Useful for direct callers.

step(state, arg2, arg3, dt)

Runs one Madgwick step against state. dt is the time since the previous step in seconds; gyro is rad/s, accel is m/s².

Types

t()

@type t() :: %BB.Estimator.Ahrs.Madgwick{
  accel_threshold: float(),
  beta: float(),
  last_monotonic_time: integer() | nil,
  q: BB.Estimator.Ahrs.Quaternion.t()
}

Functions

orientation(madgwick)

@spec orientation(t()) :: BB.Math.Quaternion.t()

Convenience: returns the current orientation as a BB.Math.Quaternion. Useful for direct callers.

step(state, arg2, arg3, dt)

@spec step(t(), {float(), float(), float()}, {float(), float(), float()}, float()) ::
  t()

Runs one Madgwick step against state. dt is the time since the previous step in seconds; gyro is rad/s, accel is m/s².

Use this directly for testing or for callers who don't want the BB.Estimator envelope.