572 lines
22 KiB
Rust
572 lines
22 KiB
Rust
use crate::dynamics::solver::AnyJointVelocityConstraint;
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use crate::dynamics::{
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joint, FixedJoint, IntegrationParameters, JointAxesMask, JointData, Multibody, MultibodyLink,
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RigidBodyVelocity,
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};
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use crate::math::{
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Isometry, JacobianSliceMut, Matrix, Real, Rotation, SpacialVector, Translation, Vector,
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ANG_DIM, DIM, SPATIAL_DIM,
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};
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use crate::utils::WCross;
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use na::{DVector, DVectorSliceMut};
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#[cfg(feature = "dim3")]
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use {
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crate::utils::WCrossMatrix,
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na::{UnitQuaternion, Vector3, VectorSlice3},
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};
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#[derive(Copy, Clone, Debug)]
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pub struct MultibodyJoint {
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pub data: JointData,
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pub(crate) coords: SpacialVector<Real>,
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pub(crate) joint_rot: Rotation<Real>,
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jacobian_v: Matrix<Real>,
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jacobian_dot_v: Matrix<Real>,
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jacobian_dot_veldiff_v: Matrix<Real>,
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}
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#[cfg(feature = "dim2")]
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fn revolute_locked_axes() -> JointAxesMask {
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JointAxesMask::X | JointAxesMask::Y
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}
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#[cfg(feature = "dim3")]
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fn revolute_locked_axes() -> JointAxesMask {
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JointAxesMask::X
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| JointAxesMask::Y
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| JointAxesMask::Z
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| JointAxesMask::ANG_Y
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| JointAxesMask::ANG_Z
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}
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impl MultibodyJoint {
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pub fn new(data: JointData) -> Self {
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Self {
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data,
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coords: na::zero(),
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joint_rot: Rotation::identity(),
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jacobian_v: na::zero(),
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jacobian_dot_v: na::zero(),
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jacobian_dot_veldiff_v: na::zero(),
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}
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}
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pub(crate) fn free(pos: Isometry<Real>) -> Self {
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let mut result = Self::new(JointData::default());
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result.set_free_pos(pos);
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result
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}
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pub(crate) fn fixed(pos: Isometry<Real>) -> Self {
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Self::new(FixedJoint::new().local_frame1(pos).into())
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}
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pub(crate) fn set_free_pos(&mut self, pos: Isometry<Real>) {
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self.coords
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.fixed_rows_mut::<DIM>(0)
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.copy_from(&pos.translation.vector);
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self.joint_rot = pos.rotation;
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}
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pub fn local_joint_rot(&self) -> &Rotation<Real> {
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&self.joint_rot
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}
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fn num_free_lin_dofs(&self) -> usize {
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let locked_bits = self.data.locked_axes.bits();
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DIM - (locked_bits & ((1 << DIM) - 1)).count_ones() as usize
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}
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/// The number of degrees of freedom allowed by the multibody_joint.
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pub fn ndofs(&self) -> usize {
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SPATIAL_DIM - self.data.locked_axes.bits().count_ones() as usize
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}
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/// The position of the multibody link containing this multibody_joint relative to its parent.
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pub fn body_to_parent(&self) -> Isometry<Real> {
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if self.data.locked_axes == revolute_locked_axes() {
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// FIXME: this is a special case for the revolute joint.
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// We have the mathematical formulation ready that works in the general case, but its
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// implementation will take some time. So let’s make a special case for the alpha
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// release and fix is soon after.
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self.data.local_frame1.translation
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* self.joint_rot
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* self.data.local_frame2.translation.inverse()
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} else {
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let locked_bits = self.data.locked_axes.bits();
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let mut transform = self.joint_rot * self.data.local_frame2.inverse();
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for i in 0..DIM {
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if (locked_bits & (1 << i)) == 0 {
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transform = Translation::from(Vector::ith(i, self.coords[i])) * transform;
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}
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}
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self.data.local_frame1 * transform
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}
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}
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/// Integrate the position of this multibody_joint.
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pub fn integrate(&mut self, dt: Real, vels: &[Real]) {
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if self.data.locked_axes == revolute_locked_axes() {
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// FIXME: this is a special case for the revolute joint.
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// We have the mathematical formulation ready that works in the general case, but its
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// implementation will take some time. So let’s make a special case for the alpha
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// release and fix is soon after.
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#[cfg(feature = "dim3")]
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let axis = self.data.local_frame1 * Vector::x_axis();
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self.coords[DIM] += vels[0] * dt;
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#[cfg(feature = "dim2")]
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{
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self.joint_rot = Rotation::from_angle(self.coords[DIM]);
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}
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#[cfg(feature = "dim3")]
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{
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self.joint_rot = Rotation::from_axis_angle(&axis, self.coords[DIM]);
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}
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} else {
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let locked_bits = self.data.locked_axes.bits();
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let mut curr_free_dof = 0;
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for i in 0..DIM {
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if (locked_bits & (1 << i)) == 0 {
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self.coords[i] += vels[curr_free_dof] * dt;
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curr_free_dof += 1;
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}
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}
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let locked_ang_bits = locked_bits >> DIM;
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let num_free_ang_dofs = ANG_DIM - locked_ang_bits.count_ones() as usize;
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match num_free_ang_dofs {
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0 => { /* No free dofs. */ }
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1 => {
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todo!()
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}
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2 => {
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todo!()
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}
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#[cfg(feature = "dim3")]
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3 => {
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let angvel = Vector3::from_row_slice(&vels[curr_free_dof..curr_free_dof + 3]);
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let disp = UnitQuaternion::new_eps(angvel * dt, 0.0);
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self.joint_rot = disp * self.joint_rot;
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}
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_ => unreachable!(),
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}
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}
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}
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/// Apply a displacement to the multibody_joint.
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pub fn apply_displacement(&mut self, disp: &[Real]) {
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self.integrate(1.0, disp);
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}
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/// Update the jacobians of this multibody_joint.
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pub fn update_jacobians(&mut self, vels: &[Real]) {
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if self.data.locked_axes == revolute_locked_axes() {
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// FIXME: this is a special case for the revolute joint.
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// We have the mathematical formulation ready that works in the general case, but its
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// implementation will take some time. So let’s make a special case for the alpha
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// release and fix is soon after.
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#[cfg(feature = "dim2")]
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let axis = 1.0;
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#[cfg(feature = "dim3")]
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let axis = self.data.local_frame1 * Vector::x_axis();
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let body_shift = self.data.local_frame2.translation.vector;
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let shift = self.joint_rot * -body_shift;
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let shift_dot_veldiff = axis.gcross(shift);
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#[cfg(feature = "dim2")]
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{
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self.jacobian_v.column_mut(0).copy_from(&axis.gcross(shift));
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}
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#[cfg(feature = "dim3")]
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{
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self.jacobian_v.column_mut(0).copy_from(&axis.gcross(shift));
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}
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self.jacobian_dot_veldiff_v
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.column_mut(0)
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.copy_from(&axis.gcross(shift_dot_veldiff));
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self.jacobian_dot_v
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.column_mut(0)
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.copy_from(&(axis.gcross(shift_dot_veldiff) * vels[0]));
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} else {
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let locked_bits = self.data.locked_axes.bits();
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let locked_ang_bits = locked_bits >> DIM;
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let num_free_ang_dofs = ANG_DIM - locked_ang_bits.count_ones() as usize;
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match num_free_ang_dofs {
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0 => { /* No free dofs. */ }
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1 => {
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todo!()
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}
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2 => {
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todo!()
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}
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#[cfg(feature = "dim3")]
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3 => {
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let num_free_lin_dofs = self.num_free_lin_dofs();
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let inv_frame2 = self.data.local_frame2.inverse();
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let shift = self.joint_rot * inv_frame2.translation.vector;
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let angvel =
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VectorSlice3::from_slice(&vels[num_free_lin_dofs..num_free_lin_dofs + 3]);
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let inv_rotmat2 = inv_frame2.rotation.to_rotation_matrix().into_inner();
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self.jacobian_v = inv_rotmat2 * shift.gcross_matrix().transpose();
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self.jacobian_dot_v =
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inv_rotmat2 * angvel.cross(&shift).gcross_matrix().transpose();
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}
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_ => unreachable!(),
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}
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}
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}
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/// Sets in `out` the non-zero entries of the multibody_joint jacobian transformed by `transform`.
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pub fn jacobian(&self, transform: &Isometry<Real>, out: &mut JacobianSliceMut<Real>) {
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if self.data.locked_axes == revolute_locked_axes() {
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// FIXME: this is a special case for the revolute joint.
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// We have the mathematical formulation ready that works in the general case, but its
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// implementation will take some time. So let’s make a special case for the alpha
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// release and fix is soon after.
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#[cfg(feature = "dim2")]
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let axis = 1.0;
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#[cfg(feature = "dim3")]
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let axis = self.data.local_frame1 * Vector::x();
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let jacobian = RigidBodyVelocity::new(self.jacobian_v.column(0).into_owned(), axis);
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out.copy_from(jacobian.transformed(transform).as_vector())
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} else {
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let locked_bits = self.data.locked_axes.bits();
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let mut curr_free_dof = 0;
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for i in 0..DIM {
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if (locked_bits & (1 << i)) == 0 {
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let transformed_axis = transform * self.data.local_frame1 * Vector::ith(i, 1.0);
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out.fixed_slice_mut::<DIM, 1>(0, curr_free_dof)
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.copy_from(&transformed_axis);
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curr_free_dof += 1;
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}
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}
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let locked_ang_bits = locked_bits >> DIM;
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let num_free_ang_dofs = ANG_DIM - locked_ang_bits.count_ones() as usize;
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match num_free_ang_dofs {
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0 => { /* No free dofs. */ }
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1 => {
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todo!()
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}
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2 => {
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todo!()
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}
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#[cfg(feature = "dim3")]
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3 => {
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let rotmat = transform.rotation.to_rotation_matrix();
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out.fixed_slice_mut::<3, 3>(0, curr_free_dof)
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.copy_from(&(rotmat * self.jacobian_v));
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out.fixed_slice_mut::<3, 3>(3, curr_free_dof)
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.copy_from(rotmat.matrix());
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}
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_ => unreachable!(),
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}
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}
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}
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/// Sets in `out` the non-zero entries of the time-derivative of the multibody_joint jacobian transformed by `transform`.
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pub fn jacobian_dot(&self, transform: &Isometry<Real>, out: &mut JacobianSliceMut<Real>) {
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if self.data.locked_axes == revolute_locked_axes() {
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// FIXME: this is a special case for the revolute joint.
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// We have the mathematical formulation ready that works in the general case, but its
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// implementation will take some time. So let’s make a special case for the alpha
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// release and fix is soon after.
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let jacobian = RigidBodyVelocity::from_vectors(
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self.jacobian_dot_v.column(0).into_owned(),
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na::zero(),
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);
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out.copy_from(jacobian.transformed(transform).as_vector())
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} else {
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let locked_bits = self.data.locked_axes.bits();
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let locked_ang_bits = locked_bits >> DIM;
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let num_free_ang_dofs = ANG_DIM - locked_ang_bits.count_ones() as usize;
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match num_free_ang_dofs {
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0 => { /* No free dofs. */ }
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1 => {
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todo!()
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}
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2 => {
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todo!()
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}
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#[cfg(feature = "dim3")]
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3 => {
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let num_free_lin_dofs = self.num_free_lin_dofs();
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let rotmat = transform.rotation.to_rotation_matrix();
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out.fixed_slice_mut::<3, 3>(0, num_free_lin_dofs)
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.copy_from(&(rotmat * self.jacobian_dot_v));
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}
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_ => unreachable!(),
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}
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}
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}
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/// Sets in `out` the non-zero entries of the velocity-derivative of the time-derivative of the multibody_joint jacobian transformed by `transform`.
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pub fn jacobian_dot_veldiff_mul_coordinates(
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&self,
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transform: &Isometry<Real>,
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acc: &[Real],
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out: &mut JacobianSliceMut<Real>,
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) {
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if self.data.locked_axes == revolute_locked_axes() {
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// FIXME: this is a special case for the revolute joint.
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// We have the mathematical formulation ready that works in the general case, but its
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// implementation will take some time. So let’s make a special case for the alpha
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// release and fix is soon after.
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let jacobian = RigidBodyVelocity::from_vectors(
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self.jacobian_dot_veldiff_v.column(0).into_owned(),
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na::zero(),
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);
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out.copy_from((jacobian.transformed(transform) * acc[0]).as_vector())
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} else {
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let locked_bits = self.data.locked_axes.bits();
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let locked_ang_bits = locked_bits >> DIM;
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let num_free_ang_dofs = ANG_DIM - locked_ang_bits.count_ones() as usize;
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match num_free_ang_dofs {
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0 => { /* No free dofs. */ }
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1 => {
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todo!()
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}
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2 => {
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todo!()
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}
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#[cfg(feature = "dim3")]
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3 => {
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let num_free_lin_dofs = self.num_free_lin_dofs();
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let angvel =
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Vector3::from_row_slice(&acc[num_free_lin_dofs..num_free_lin_dofs + 3]);
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let rotmat = transform.rotation.to_rotation_matrix();
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let res = rotmat * angvel.gcross_matrix() * self.jacobian_v;
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out.fixed_slice_mut::<3, 3>(0, num_free_lin_dofs)
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.copy_from(&res);
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}
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_ => unreachable!(),
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}
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}
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}
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/// Multiply the multibody_joint jacobian by generalized velocities to obtain the
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/// relative velocity of the multibody link containing this multibody_joint.
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pub fn jacobian_mul_coordinates(&self, acc: &[Real]) -> RigidBodyVelocity {
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if self.data.locked_axes == revolute_locked_axes() {
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// FIXME: this is a special case for the revolute joint.
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// We have the mathematical formulation ready that works in the general case, but its
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// implementation will take some time. So let’s make a special case for the alpha
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// release and fix is soon after.
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#[cfg(feature = "dim2")]
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let axis = 1.0;
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#[cfg(feature = "dim3")]
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let axis = self.data.local_frame1 * Vector::x();
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RigidBodyVelocity::new(self.jacobian_v.column(0).into_owned(), axis) * acc[0]
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} else {
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let locked_bits = self.data.locked_axes.bits();
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let mut result = RigidBodyVelocity::zero();
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let mut curr_free_dof = 0;
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for i in 0..DIM {
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if (locked_bits & (1 << i)) == 0 {
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result.linvel += self.data.local_frame1 * Vector::ith(i, acc[curr_free_dof]);
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curr_free_dof += 1;
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}
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}
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let locked_ang_bits = locked_bits >> DIM;
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let num_free_ang_dofs = ANG_DIM - locked_ang_bits.count_ones() as usize;
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match num_free_ang_dofs {
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0 => { /* No free dofs. */ }
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1 => {
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todo!()
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}
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2 => {
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todo!()
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}
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#[cfg(feature = "dim3")]
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3 => {
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let angvel = Vector3::from_row_slice(&acc[curr_free_dof..curr_free_dof + 3]);
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let linvel = self.jacobian_v * angvel;
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result += RigidBodyVelocity::new(linvel, angvel);
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}
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_ => unreachable!(),
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}
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result
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}
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}
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/// Multiply the multibody_joint jacobian by generalized accelerations to obtain the
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/// relative acceleration of the multibody link containing this multibody_joint.
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pub fn jacobian_dot_mul_coordinates(&self, acc: &[Real]) -> RigidBodyVelocity {
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if self.data.locked_axes == revolute_locked_axes() {
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// FIXME: this is a special case for the revolute joint.
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// We have the mathematical formulation ready that works in the general case, but its
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// implementation will take some time. So let’s make a special case for the alpha
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// release and fix is soon after.
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RigidBodyVelocity::from_vectors(self.jacobian_dot_v.column(0).into_owned(), na::zero())
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* acc[0]
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} else {
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let locked_bits = self.data.locked_axes.bits();
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let locked_ang_bits = locked_bits >> DIM;
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let num_free_ang_dofs = ANG_DIM - locked_ang_bits.count_ones() as usize;
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match num_free_ang_dofs {
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0 => {
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/* No free dofs. */
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RigidBodyVelocity::zero()
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}
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1 => {
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todo!()
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}
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2 => {
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todo!()
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}
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#[cfg(feature = "dim3")]
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3 => {
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let num_free_lin_dofs = self.num_free_lin_dofs();
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let angvel =
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Vector3::from_row_slice(&acc[num_free_lin_dofs..num_free_lin_dofs + 3]);
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let linvel = self.jacobian_dot_v * angvel;
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RigidBodyVelocity::new(linvel, na::zero())
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}
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_ => unreachable!(),
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}
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}
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}
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/// Fill `out` with the non-zero entries of a damping that can be applied by default to ensure a good stability of the multibody_joint.
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pub fn default_damping(&self, out: &mut DVectorSliceMut<Real>) {
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let locked_bits = self.data.locked_axes.bits();
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let mut curr_free_dof = self.num_free_lin_dofs();
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// A default damping only for the angular dofs
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for i in DIM..SPATIAL_DIM {
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if locked_bits & (1 << i) == 0 {
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// This is a free angular DOF.
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out[curr_free_dof] = 0.2;
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curr_free_dof += 1;
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}
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}
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}
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/// Maximum number of velocity constrains that can be generated by this multibody_joint.
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pub fn num_velocity_constraints(&self) -> usize {
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let locked_bits = self.data.locked_axes.bits();
|
||
let limit_bits = self.data.limit_axes.bits();
|
||
let motor_bits = self.data.motor_axes.bits();
|
||
let mut num_constraints = 0;
|
||
|
||
for i in 0..SPATIAL_DIM {
|
||
if (locked_bits & (1 << i)) == 0 {
|
||
if (limit_bits & (1 << i)) != 0 {
|
||
num_constraints += 1;
|
||
}
|
||
if (motor_bits & (1 << i)) != 0 {
|
||
num_constraints += 1;
|
||
}
|
||
}
|
||
}
|
||
|
||
num_constraints
|
||
}
|
||
|
||
/// Initialize and generate velocity constraints to enforce, e.g., multibody_joint limits and motors.
|
||
pub fn velocity_constraints(
|
||
&self,
|
||
params: &IntegrationParameters,
|
||
multibody: &Multibody,
|
||
link: &MultibodyLink,
|
||
dof_id: usize,
|
||
j_id: &mut usize,
|
||
jacobians: &mut DVector<Real>,
|
||
constraints: &mut Vec<AnyJointVelocityConstraint>,
|
||
) {
|
||
let locked_bits = self.data.locked_axes.bits();
|
||
let limit_bits = self.data.limit_axes.bits();
|
||
let motor_bits = self.data.motor_axes.bits();
|
||
let mut curr_free_dof = 0;
|
||
|
||
for i in 0..DIM {
|
||
if (locked_bits & (1 << i)) == 0 {
|
||
if (limit_bits & (1 << i)) != 0 {
|
||
joint::unit_joint_limit_constraint(
|
||
params,
|
||
multibody,
|
||
link,
|
||
[self.data.limits[i].min, self.data.limits[i].max],
|
||
self.coords[i],
|
||
dof_id + curr_free_dof,
|
||
j_id,
|
||
jacobians,
|
||
constraints,
|
||
);
|
||
}
|
||
|
||
if (motor_bits & (1 << i)) != 0 {
|
||
joint::unit_joint_motor_constraint(
|
||
params,
|
||
multibody,
|
||
link,
|
||
&self.data.motors[i],
|
||
self.coords[i],
|
||
dof_id + curr_free_dof,
|
||
j_id,
|
||
jacobians,
|
||
constraints,
|
||
);
|
||
}
|
||
curr_free_dof += 1;
|
||
}
|
||
}
|
||
|
||
/*
|
||
let locked_ang_bits = locked_bits >> DIM;
|
||
let num_free_ang_dofs = ANG_DIM - locked_ang_bits.count_ones() as usize;
|
||
match num_free_ang_dofs {
|
||
0 => { /* No free dofs. */ }
|
||
1 => {}
|
||
2 => {
|
||
todo!()
|
||
}
|
||
3 => {}
|
||
_ => unreachable!(),
|
||
}
|
||
*/
|
||
// TODO: we should make special cases for multi-angular-dofs limits/motors
|
||
for i in DIM..SPATIAL_DIM {
|
||
if (locked_bits & (1 << i)) == 0 {
|
||
if (limit_bits & (1 << i)) != 0 {
|
||
joint::unit_joint_limit_constraint(
|
||
params,
|
||
multibody,
|
||
link,
|
||
[self.data.limits[i].min, self.data.limits[i].max],
|
||
self.coords[i],
|
||
dof_id + curr_free_dof,
|
||
j_id,
|
||
jacobians,
|
||
constraints,
|
||
);
|
||
}
|
||
|
||
if (motor_bits & (1 << i)) != 0 {
|
||
joint::unit_joint_motor_constraint(
|
||
params,
|
||
multibody,
|
||
link,
|
||
&self.data.motors[i],
|
||
self.coords[i],
|
||
dof_id + curr_free_dof,
|
||
j_id,
|
||
jacobians,
|
||
constraints,
|
||
);
|
||
}
|
||
curr_free_dof += 1;
|
||
}
|
||
}
|
||
}
|
||
}
|