Struct Tendon 

pub struct Tendon {
    pub path: Vec<usize>,
    pub stiffness: f64,
    pub rest_length: f64,
    pub max_force: f64,
    pub damping: f64,
}

A tendon is a spring-damper system that follows a path through multiple bodies.

It generates forces along the path based on the current length vs. rest length.

Fields

path: Vec<usize>

Sequence of body indices defining the tendon path.

stiffness: f64

Spring stiffness (N/m or Nm/rad).

rest_length: f64

Rest length (m).

max_force: f64

Maximum force the tendon can exert (N).

damping: f64

Damping coefficient (Ns/m).

Implementations

impl Tendon

pub fn new( path: Vec<usize>, stiffness: f64, rest_length: f64, max_force: f64, ) -> Tendon

Create a new tendon with the given parameters.

pub fn with_damping(self, damping: f64) -> Tendon

Create a new tendon with damping.

pub fn current_length(&self, state: &State) -> f64

Compute the current length of the tendon.

Sums the Euclidean distances between consecutive bodies in the path.

pub fn current_length_rate(&self, _state: &State) -> f64

Compute the rate of change of tendon length.

This requires velocities, which we approximate from body transforms. For now, return 0.0 (proper implementation requires forward kinematics with velocities).

pub fn compute_forces(&self, state: &State) -> Vec<(usize, SpatialVec)>

Compute forces applied to each body in the tendon path.

Returns a vector of (body_idx, force) pairs. Force is a SpatialVec (6D force/torque in world frame).

pub fn is_valid(&self, model: &Model) -> bool

Check if tendon is valid for the given model.

Trait Implementations

impl Clone for Tendon

fn clone(&self) -> Tendon

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Tendon

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

Formats the value using the given formatter.