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use nalgebra::{Matrix6, DMatrix, DVector, U6};
use crate::geometry::{Twist};
use crate::chains::{Chain};
use crate::jacobian::{Jacobian, JacobianSolver};
use crate::svd_eigen::{SvdResult};
pub type WeightTaskSpace = Matrix6<f64>;
pub type WeightJointSpace = DMatrix<f64>;
type JointQdots = DVector<f64>;
fn transform_vectors(in_vector: JointQdots) -> Vec<f64> {
let mut result = Vec::with_capacity(in_vector.nrows());
for i in 0..in_vector.nrows() {
result.push(in_vector[i]);
}
result
}
pub struct InverseDiffKinematicsSolver {
chain: Chain,
weight_task_space: WeightTaskSpace,
weight_joint_space: WeightJointSpace,
jacobian: Jacobian,
temp_qdot: JointQdots,
svd_result: SvdResult,
lambda: f64,
epsilon: f64,
maxiter: usize,
n_joints: usize,
}
impl InverseDiffKinematicsSolver{
pub fn new(in_chain: Chain) -> Self{
let num_joints = in_chain.get_num_joints();
Self{
chain: in_chain,
weight_task_space: WeightTaskSpace::identity(),
weight_joint_space: WeightJointSpace::identity(
num_joints, num_joints),
jacobian: Jacobian::zeros(num_joints),
temp_qdot: JointQdots::zeros(num_joints),
svd_result: SvdResult::new(num_joints),
lambda: 0.0,
epsilon: 1e-300,
maxiter: 150,
n_joints: num_joints,
}
}
pub fn set_weights(&mut self,
task_space: WeightTaskSpace,
joint_space: WeightJointSpace) {
if joint_space.ncols() != joint_space.nrows() {
panic!("Joint space matrix must be square. Got {}x{}",
joint_space.nrows(), joint_space.ncols());
}
if joint_space.ncols() != self.n_joints {
panic!("Wrong joint space matrix size. Expected {},\
got {}", self.n_joints, joint_space.nrows());
}
self.weight_task_space = task_space;
self.weight_joint_space = joint_space;
}
pub fn set_lambda(&mut self, new_lambda: f64) {
self.lambda = new_lambda;
}
pub fn set_convergence(&mut self, new_epsilon: f64, new_maxiter: usize){
if new_epsilon <= 0.0 {
panic!("Epsilon must be positive! got {}", new_epsilon);
}
self.epsilon = new_epsilon;
self.maxiter = new_maxiter;
}
pub fn solve(
&mut self, twist: &Twist, init_angles: &Vec<f64>) -> Vec<f64> {
let mut num_small_sigmas = 0;
self.jacobian.solve_from_chain(&self.chain, init_angles);
let weight_jac = self.weight_task_space * &self.jacobian *
&self.weight_joint_space;
self.svd_result.compute(&weight_jac, self.epsilon, self.maxiter);
let u_matrix = &self.svd_result.u_matrix;
let v_matrix = &self.svd_result.v_matrix;
let singular_values = &self.svd_result.s_vector;
let temp_ts = self.weight_task_space *
u_matrix.fixed_slice::<U6, U6>(0,0);
let temp_js = &self.weight_joint_space * v_matrix;
let sigma_min = if self.n_joints >= 6 {
singular_values[5]
} else {
0.0
};
for col in 0..self.n_joints {
let mut sum = 0.0;
for row in 0..6 {
if col < 6 {
sum += temp_ts[(row, col)]*twist[row]
}
}
let lambda_scaled = if sigma_min < self.epsilon {
(1.0-(sigma_min/self.epsilon)*(sigma_min/self.epsilon))
.sqrt()*self.lambda
} else {0.0};
self.temp_qdot[col] = if singular_values[col].abs() < self.epsilon {
num_small_sigmas += 1;
if col < 6 {
let sigma = singular_values[col];
sum*((sigma/(sigma*sigma+lambda_scaled*lambda_scaled)))
} else {
0.0
}
} else {
sum/singular_values[col]
};
}
let qdot_out = self.chain.get_coupling_matrix() * temp_js * &self.temp_qdot;
if num_small_sigmas > (self.n_joints - 6) {
panic!{"The pseudo inverse converged but it is Singular"};
}
transform_vectors(qdot_out)
}
}
#[cfg(test)]
mod test {
use crate::inverse_diff_kinematics::{InverseDiffKinematicsSolver};
use crate::geometry::{Twist, get_twist_error};
use crate::chains::tests::{create_testing_chain};
use crate::forward_diff_kinematics::{ForwardDiffKinematicsSolver};
#[test]
fn inverse_kinematics_correct() {
let chain = create_testing_chain();
let for_solver = ForwardDiffKinematicsSolver::new(chain.clone());
let angles = vec![0.1, -0.95, 0.57, 0.68, -0.27, 0.39, 0.47];
let twist = Twist::new(
-0.423878, -1.01074, 0.123592, -2.28297, 0.209941, 1.80897);
let mut inv_solver = InverseDiffKinematicsSolver::new(chain.clone());
let inv_result = inv_solver.solve(
&twist, &angles);
assert_eq!(7, inv_result.len());
let forward_result = for_solver.solve(
&angles, &inv_result);
assert!(get_twist_error(forward_result, twist) < 0.0001);
}
}