adam.parametric.jax

Submodules

• adam.parametric.jax.computations_parametric

Classes

KinDynComputationsParametric

This is a small class that retrieves robot quantities using Jax for Floating Base systems.

Package Contents

class adam.parametric.jax.KinDynComputationsParametric(urdfstring: str, joints_name_list: list, links_name_list: list, root_link: str = None, gravity: numpy.array = jnp.array([0, 0, -9.80665, 0, 0, 0]))

This is a small class that retrieves robot quantities using Jax for Floating Base systems. This is parametric w.r.t the link length and densities.

math

links_name_list

g

urdfstring

joints_name_list

representation

set_frame_velocity_representation(representation: adam.core.constants.Representations) → None

Sets the representation of the velocity of the frames

Parameters:

representation (Representations) – The representation of the velocity

mass_matrix(base_transform: jax.numpy.array, joint_positions: jax.numpy.array, length_multiplier: jax.numpy.array, densities: jax.numpy.array)

Returns the Mass Matrix functions computed the CRBA

Parameters:

• base_transform (jnp.array) – The homogenous transform from base to world frame

• joint_positions (jnp.array) – The joints position

• length_multiplier (jnp.array) – The length multiplier of the parametrized links

• densities (jnp.array) – The densities of the parametrized links

Returns:

Mass Matrix

Return type:

M (jnp.array)

centroidal_momentum_matrix(base_transform: jax.numpy.array, joint_positions: jax.numpy.array, length_multiplier: jax.numpy.array, densities: jax.numpy.array)

Returns the Centroidal Momentum Matrix functions computed the CRBA

Parameters:

• base_transform (jnp.array) – The homogenous transform from base to world frame

• joint_positions (jnp.array) – The joints position

• length_multiplier (jnp.array) – The length multiplier of the parametrized links

• densities (jnp.array) – The densities of the parametrized links

Returns:

Centroidal Momentum matrix

Return type:

Jcc (jnp.array)

relative_jacobian(frame: str, joint_positions: jax.numpy.array, length_multiplier: jax.numpy.array, densities: jax.numpy.array)

Returns the Jacobian between the root link and a specified frame frames

Parameters:

• frame (str) – The tip of the chain

• joint_positions (jnp.array) – The joints position

• length_multiplier (jnp.array) – The length multiplier of the parametrized links

• densities (jnp.array) – The densities of the parametrized links

Returns:

The Jacobian between the root and the frame

Return type:

J (jnp.array)

jacobian_dot(frame: str, base_transform: jax.numpy.array, joint_positions: jax.numpy.array, base_velocity: jax.numpy.array, joint_velocities: jax.numpy.array, length_multiplier: jax.numpy.array, densities: jax.numpy.array) → jax.numpy.array

Returns the Jacobian derivative relative to the specified frame

Parameters:

• frame (str) – The frame to which the jacobian will be computed

• base_transform (jnp.array) – The homogenous transform from base to world frame

• joint_positions (jnp.array) – The joints position

• base_velocity (jnp.array) – The base velocity

• joint_velocities (jnp.array) – The joint velocities

• length_multiplier (jnp.array) – The length multiplier of the parametrized links

• densities (jnp.array) – The densities of the parametrized links

Returns:

The Jacobian derivative relative to the frame

Return type:

Jdot (jnp.array)

forward_kinematics(frame: str, base_transform: jax.numpy.array, joint_positions: jax.numpy.array, length_multiplier: jax.numpy.array, densities: jax.numpy.array)

Computes the forward kinematics relative to the specified frame

Parameters:

• frame (str) – The frame to which the fk will be computed

• base_transform (jnp.array) – The homogenous transform from base to world frame

• joint_positions (jnp.array) – The joints position

• length_multiplier (jnp.array) – The length multiplier of the parametrized links

• densities (jnp.array) – The densities of the parametrized links

Returns:

The fk represented as Homogenous transformation matrix

Return type:

T_fk (jnp.array)

forward_kinematics_fun(frame, length_multiplier: jax.numpy.array, densities: jax.numpy.array)

jacobian(frame: str, base_transform, joint_positions, length_multiplier: jax.numpy.array, densities: jax.numpy.array)

Returns the Jacobian relative to the specified frame

Args

frame (str): The frame to which the jacobian will be computed base_transform (jnp.array): The homogenous transform from base to world frame s (jnp.array): The joints position length_multiplier (jnp.array): The length multiplier of the parametrized links densities (jnp.array): The densities of the parametrized links

Returns:

The Jacobian relative to the frame

Return type:

J_tot (jnp.array)

bias_force(base_transform: jax.numpy.array, joint_positions: jax.numpy.array, base_velocity: jax.numpy.array, s_dot: jax.numpy.array, length_multiplier: jax.numpy.array, densities: jax.numpy.array) → jax.numpy.array

Returns the bias force of the floating-base dynamics ejoint_positionsuation, using a reduced RNEA (no acceleration and external forces)

Parameters:

• base_transform (jnp.array) – The homogenous transform from base to world frame

• joint_positions (jnp.array) – The joints position

• base_velocity (jnp.array) – The base velocity

• s_dot (jnp.array) – The joints velocity

• length_multiplier (jnp.array) – The length multiplier of the parametrized links

• densities (jnp.array) – The densities of the parametrized links

Returns:

the bias force

Return type:

h (jnp.array)

coriolis_term(base_transform: jax.numpy.array, joint_positions: jax.numpy.array, base_velocity: jax.numpy.array, s_dot: jax.numpy.array, length_multiplier: jax.numpy.array, densities: jax.numpy.array) → jax.numpy.array

Returns the coriolis term of the floating-base dynamics ejoint_positionsuation, using a reduced RNEA (no acceleration and external forces)

Parameters:

• base_transform (jnp.array) – The homogenous transform from base to world frame

• joint_positions (jnp.array) – The joints position

• base_velocity (jnp.array) – The base velocity

• s_dot (jnp.array) – The joints velocity

• length_multiplier (jnp.array) – The length multiplier of the parametrized links

• densities (jnp.array) – The densities of the parametrized links

Returns:

the Coriolis term

Return type:

C (jnp.array)

gravity_term(base_transform: jax.numpy.array, joint_positions: jax.numpy.array, length_multiplier: jax.numpy.array, densities: jax.numpy.array) → jax.numpy.array

Returns the gravity term of the floating-base dynamics ejoint_positionsuation, using a reduced RNEA (no acceleration and external forces)

Parameters:

• base_transform (jnp.array) – The homogenous transform from base to world frame

• joint_positions (jnp.array) – The joints position

• length_multiplier (jnp.array) – The length multiplier of the parametrized links

• densities (jnp.array) – The densities of the parametrized links

Returns:

the gravity term

Return type:

G (jnp.array)

CoM_position(base_transform: jax.numpy.array, joint_positions: jax.numpy.array, length_multiplier: jax.numpy.array, densities: jax.numpy.array) → jax.numpy.array

Returns the CoM position

Parameters:

• base_transform (jnp.array) – The homogenous transform from base to world frame

• joint_positions (jnp.array) – The joints position

• length_multiplier (jnp.array) – The length multiplier of the parametrized links

• densities (jnp.array) – The densities of the parametrized links

Returns:

The CoM position

Return type:

com (jnp.array)

get_total_mass(length_multiplier: jax.numpy.array, densities: jax.numpy.array) → float

Returns the total mass of the robot

Parameters:

• length_multiplier (jnp.array) – The length multiplier of the parametrized links

• densities (jnp.array) – The densities of the parametrized links

Returns:

The total mass

Return type:

mass

get_original_densities() → list[float]

Returns the original densities of the parametric links

Returns:

The original densities of the parametric links

Return type:

densities