Struct ArmFeedForward 

pub struct ArmFeedForward { /* private fields */ }

Feedforward controller for arm mechanisms with gravity compensation.

Extends FeedForward with a gravity compensation term that accounts for the arm’s position. This is essential for arms that must hold position against gravity.

Formula

voltage = ks * sign(v) + kv * v + ka * a + kg * g(angle)

Where g(angle) is a function that returns the gravity effect at the given angle (typically cos(angle) for a simple arm).

Example

use kernelvex::{ArmFeedForward, QAngle};

let ff = ArmFeedForward::new(0.1, 0.5, 0.01, 0.3);

// Calculate with gravity compensation using cosine
let voltage = ff.calculate(
    QAngle::from_degrees(45.0),
    target_velocity,
    target_acceleration,
    |angle| angle.cos(),
);

Implementations

impl ArmFeedForward

pub const fn new(ks: f64, kv: f64, ka: f64, kg: f64) -> Self

Creates a new arm feedforward controller with the given gains.

Arguments

• ks - Static friction compensation
• kv - Velocity feedforward gain
• ka - Acceleration feedforward gain
• kg - Gravity compensation gain

pub const fn ks(&self) -> f64

Returns the static friction gain.

pub const fn kv(&self) -> f64

Returns the velocity feedforward gain.

pub const fn ka(&self) -> f64

Returns the acceleration feedforward gain.

pub const fn kg(&self) -> f64

Returns the gravity compensation gain.

pub const fn set_gains(self, ks: f64, kv: f64, ka: f64, kg: f64) -> Self

Sets all gains at once, returning a new instance.

pub const fn set_ks(self, ks: f64) -> Self

Sets the static friction gain, returning a new instance.

pub const fn set_kv(self, kv: f64) -> Self

Sets the velocity gain, returning a new instance.

pub const fn set_ka(self, ka: f64) -> Self

Sets the acceleration gain, returning a new instance.

pub const fn set_kg(self, kg: f64) -> Self

Sets the gravity gain, returning a new instance.

pub fn calculate( &self, angle: QAngle, velocity: f64, acceleration: f64, g: impl Fn(QAngle) -> f64, ) -> f64

Calculates the feedforward voltage with gravity compensation.

Arguments

• angle - Current arm angle
• velocity - Desired velocity
• acceleration - Desired acceleration
• g - Gravity function that takes angle and returns gravity effect

Returns

The feedforward voltage output including gravity compensation.

Example

// Using cosine for simple arm
let voltage = ff.calculate(angle, vel, acc, |a| a.cos());

// Using custom gravity function
let voltage = ff.calculate(angle, vel, acc, |a| {
    // Custom gravity calculation for 4-bar linkage
    (a + offset).cos() * linkage_factor
});