Struct Complementary 

pub struct Complementary { /* private fields */ }

Blends a drifting rate measurement with a noisy absolute one into a steady estimate.

A gyroscope gives a smooth rate of turn but drifts over time; an accelerometer gives an absolute tilt that is right on average but noisy. A complementary filter trusts the rate over the short term and the absolute reading over the long term, so the result is both smooth and drift-free. Each step it integrates the rate onto its estimate, then nudges that toward the absolute reading by an amount set by alpha. The same filter fuses any fast-rate-plus-slow-absolute pair, not only an IMU.

Examples

use pamoja_kit::Complementary;

// Heavily trust the integrated rate, lightly correct toward the absolute reading.
let mut tilt = Complementary::new(0.98, 0.0);
// The rate reads +10 per second for 0.1 s while the absolute reads about 1.
let angle = tilt.update(10.0, 1.0, 0.1);
assert!((angle - 1.0).abs() < 0.05); // about 0.98 * 1 + 0.02 * 1

Implementations

impl Complementary

pub fn new(alpha: f32, initial: f32) -> Self

Creates a filter.

Arguments

• alpha - the weight on the integrated rate, in [0.0, 1.0]; near 1.0 trusts the rate and corrects slowly, near 0.0 follows the absolute reading. Clamped to the unit interval, and one that is not a number is taken as 0.0, which follows the absolute reading since that one cannot drift.
• initial - the starting estimate.

Returns

A filter seeded with initial.

pub fn update(&mut self, rate: f32, absolute: f32, dt: f32) -> f32

Fuses a rate and an absolute reading over a time step and returns the new estimate.

If the rate, the absolute reading, or the time step is not a finite number, such as the NaN a failed sensor reports, the update is ignored and the estimate returned as it stood.

Arguments

• rate - the rate of change, such as degrees per second from a gyroscope.
• absolute - the absolute reading, such as a tilt from an accelerometer.
• dt - the time since the previous update.

Returns

The fused estimate, alpha * (estimate + rate * dt) + (1 - alpha) * absolute.

pub fn estimate(&self) -> f32

Returns the current fused estimate.

Trait Implementations

impl Clone for Complementary

fn clone(&self) -> Complementary

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for Complementary

impl Debug for Complementary

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.