PyBullet Class

class panda_gym.pybullet.PyBullet(render_mode: str = 'rgb_array', n_substeps: int = 20, background_color: ndarray | None = None, renderer: str = 'Tiny')

Convenient class to use PyBullet physics engine.

Parameters:

  • render_mode (str, optional) – Render mode. Defaults to “rgb_array”.

  • n_substeps (int, optional) – Number of sim substep when step() is called. Defaults to 20.

  • background_color (np.ndarray, optional) – The background color as (red, green, blue). Defaults to np.array([223, 54, 45]).

  • renderer (str, optional) – Renderer, either “Tiny” or OpenGL”. Defaults to “Tiny” if render mode is “human” and “OpenGL” if render mode is “rgb_array”. Only “OpenGL” is available for human render mode.

close() → None

Close the simulation.

control_joints(body: str, joints: ndarray, target_angles: ndarray, forces: ndarray) → None

Control the joints motor.

Parameters:

  • body (str) – Body unique name.

  • joints (np.ndarray) – List of joint indices, as a list of ints.

  • target_angles (np.ndarray) – List of target angles, as a list of floats.

  • forces (np.ndarray) – Forces to apply, as a list of floats.

create_box(body_name: str, half_extents: ndarray, mass: float, position: ndarray, rgba_color: ndarray | None = None, specular_color: ndarray | None = None, ghost: bool = False, lateral_friction: float | None = None, spinning_friction: float | None = None, texture: str | None = None) → None

Create a box.

Parameters:

  • body_name (str) – The name of the body. Must be unique in the sim.

  • half_extents (np.ndarray) – Half size of the box in meters, as (x, y, z).

  • mass (float) – The mass in kg.

  • position (np.ndarray) – The position, as (x, y, z).

  • rgba_color (np.ndarray, optional) – Body color, as (r, g, b, a). Defaults as [0, 0, 0, 0]

  • specular_color (np.ndarray, optional) – Specular color, as (r, g, b). Defaults to [0, 0, 0].

  • ghost (bool, optional) – Whether the body can collide. Defaults to False.

  • lateral_friction (float or None, optional) – Lateral friction. If None, use the default pybullet value. Defaults to None.

  • spinning_friction (float or None, optional) – Spinning friction. If None, use the default pybullet value. Defaults to None.

  • texture (str or None, optional) – Texture file name. Defaults to None.

create_cylinder(body_name: str, radius: float, height: float, mass: float, position: ndarray, rgba_color: ndarray | None = None, specular_color: ndarray | None = None, ghost: bool = False, lateral_friction: float | None = None, spinning_friction: float | None = None) → None

Create a cylinder.

Parameters:

  • body_name (str) – The name of the body. Must be unique in the sim.

  • radius (float) – The radius in meter.

  • height (float) – The height in meter.

  • mass (float) – The mass in kg.

  • position (np.ndarray) – The position, as (x, y, z).

  • rgba_color (np.ndarray, optional) – Body color, as (r, g, b, a). Defaults as [0, 0, 0, 0]

  • specular_color (np.ndarray, optional) – Specular color, as (r, g, b). Defaults to [0, 0, 0].

  • ghost (bool, optional) – Whether the body can collide. Defaults to False.

  • lateral_friction (float or None, optional) – Lateral friction. If None, use the default pybullet value. Defaults to None.

  • spinning_friction (float or None, optional) – Spinning friction. If None, use the default pybullet value. Defaults to None.

create_plane(z_offset: float) → None

Create a plane. (Actually, it is a thin box.)

Parameters:

z_offset (float) – Offset of the plane.

create_sphere(body_name: str, radius: float, mass: float, position: ndarray, rgba_color: ndarray | None = None, specular_color: ndarray | None = None, ghost: bool = False, lateral_friction: float | None = None, spinning_friction: float | None = None) → None

Create a sphere.

Parameters:

  • body_name (str) – The name of the body. Must be unique in the sim.

  • radius (float) – The radius in meter.

  • mass (float) – The mass in kg.

  • position (np.ndarray) – The position, as (x, y, z).

  • rgba_color (np.ndarray, optional) – Body color, as (r, g, b, a). Defaults as [0, 0, 0, 0]

  • specular_color (np.ndarray, optional) – Specular color, as (r, g, b). Defaults to [0, 0, 0].

  • ghost (bool, optional) – Whether the body can collide. Defaults to False.

  • lateral_friction (float or None, optional) – Lateral friction. If None, use the default pybullet value. Defaults to None.

  • spinning_friction (float or None, optional) – Spinning friction. If None, use the default pybullet value. Defaults to None.

create_table(length: float, width: float, height: float, x_offset: float = 0.0, lateral_friction: float | None = None, spinning_friction: float | None = None) → None

Create a fixed table. Top is z=0, centered in y.

Parameters:

  • length (float) – The length of the table (x direction).

  • width (float) – The width of the table (y direction)

  • height (float) – The height of the table.

  • x_offset (float, optional) – The offet in the x direction.

  • lateral_friction (float or None, optional) – Lateral friction. If None, use the default pybullet value. Defaults to None.

  • spinning_friction (float or None, optional) – Spinning friction. If None, use the default pybullet value. Defaults to None.

property dt

Timestep.

get_base_angular_velocity(body: str) → ndarray

Get the angular velocity of the body.

Parameters:

body (str) – Body unique name.

Returns:

np.ndarray – The angular velocity, as (wx, wy, wz).

get_base_orientation(body: str) → ndarray

Get the orientation of the body.

Parameters:

body (str) – Body unique name.

Returns:

np.ndarray – The orientation, as quaternion (x, y, z, w).

get_base_position(body: str) → ndarray

Get the position of the body.

Parameters:

body (str) – Body unique name.

Returns:

np.ndarray – The position, as (x, y, z).

get_base_rotation(body: str, type: str = 'euler') → ndarray

Get the rotation of the body.

Parameters:

  • body (str) – Body unique name.

  • type (str) – Type of angle, either “euler” or “quaternion”

Returns:

np.ndarray – The rotation.

get_base_velocity(body: str) → ndarray

Get the velocity of the body.

Parameters:

body (str) – Body unique name.

Returns:

np.ndarray – The velocity, as (vx, vy, vz).

get_joint_angle(body: str, joint: int) → float

Get the angle of the joint of the body.

Parameters:

  • body (str) – Body unique name.

  • joint (int) – Joint index in the body

Returns:

float – The angle.

get_joint_velocity(body: str, joint: int) → float

Get the velocity of the joint of the body.

Parameters:

  • body (str) – Body unique name.

  • joint (int) – Joint index in the body

Returns:

float – The velocity.

Get the angular velocity of the link of the body.

Parameters:

  • body (str) – Body unique name.

  • link (int) – Link index in the body.

Returns:

np.ndarray – The angular velocity, as (wx, wy, wz).

Get the orientation of the link of the body.

Parameters:

  • body (str) – Body unique name.

  • link (int) – Link index in the body.

Returns:

np.ndarray – The rotation, as (rx, ry, rz).

Get the position of the link of the body.

Parameters:

  • body (str) – Body unique name.

  • link (int) – Link index in the body.

Returns:

np.ndarray – The position, as (x, y, z).

Get the velocity of the link of the body.

Parameters:

  • body (str) – Body unique name.

  • link (int) – Link index in the body.

Returns:

np.ndarray – The velocity, as (vx, vy, vz).

inverse_kinematics(body: str, link: int, position: ndarray, orientation: ndarray) → ndarray

Compute the inverse kinematics and return the new joint state.

Parameters:

  • body (str) – Body unique name.

  • link (int) – Link index in the body.

  • position (np.ndarray) – Desired position of the end-effector, as (x, y, z).

  • orientation (np.ndarray) – Desired orientation of the end-effector as quaternion (x, y, z, w).

Returns:

np.ndarray – The new joint state.

loadURDF(body_name: str, **kwargs: Any) → None

Load URDF file.

Parameters:

body_name (str) – The name of the body. Must be unique in the sim.

no_rendering() → Iterator[None]

Disable rendering within this context.

place_visualizer(target_position: ndarray, distance: float, yaw: float, pitch: float) → None

Orient the camera used for rendering.

Parameters:

  • target (np.ndarray) – Target position, as (x, y, z).

  • distance (float) – Distance from the target position.

  • yaw (float) – Yaw.

  • pitch (float) – Pitch.

remove_state(state_id: int) → None

Remove a simulation state. This will make this state_id available again for returning in save_state().

Parameters:

state_id – The simulation state id returned by save_state().

render(width: int = 720, height: int = 480, target_position: ndarray | None = None, distance: float = 1.4, yaw: float = 45, pitch: float = -30, roll: float = 0) → ndarray | None

Render.

If render mode is “rgb_array”, return an RGB array of the scene. Else, do nothing and return None.

Parameters:

  • width (int, optional) – Image width. Defaults to 720.

  • height (int, optional) – Image height. Defaults to 480.

  • target_position (np.ndarray, optional) – Camera targetting this postion, as (x, y, z). Defaults to [0., 0., 0.].

  • distance (float, optional) – Distance of the camera. Defaults to 1.4.

  • yaw (float, optional) – Yaw of the camera. Defaults to 45.

  • pitch (float, optional) – Pitch of the camera. Defaults to -30.

  • roll (int, optional) – Rool of the camera. Defaults to 0.

  • mode (str, optional) – Deprecated: This argument is deprecated and will be removed in a future version. Use the render_mode argument of the constructor instead.

Returns:

RGB np.ndarray or None – An RGB array if mode is ‘rgb_array’, else None.

restore_state(state_id: int) → None

Restore a simulation state.

Parameters:

state_id – The simulation state id returned by save_state().

save_state() → int

Save the current simulation state.

Returns:

  • int – A state id assigned by PyBullet, which is the first non-negative

  • integer available for indexing.

set_base_pose(body: str, position: ndarray, orientation: ndarray) → None

Set the position of the body.

Parameters:

  • body (str) – Body unique name.

  • position (np.ndarray) – The position, as (x, y, z).

  • orientation (np.ndarray) – The target orientation as quaternion (x, y, z, w).

set_joint_angle(body: str, joint: int, angle: float) → None

Set the angle of the joint of the body.

Parameters:

  • body (str) – Body unique name.

  • joint (int) – Joint index in the body.

  • angle (float) – Target angle.

set_joint_angles(body: str, joints: ndarray, angles: ndarray) → None

Set the angles of the joints of the body.

Parameters:

  • body (str) – Body unique name.

  • joints (np.ndarray) – List of joint indices, as a list of ints.

  • angles (np.ndarray) – List of target angles, as a list of floats.

set_lateral_friction(body: str, link: int, lateral_friction: float) → None

Set the lateral friction of a link.

Parameters:

  • body (str) – Body unique name.

  • link (int) – Link index in the body.

  • lateral_friction (float) – Lateral friction.

set_spinning_friction(body: str, link: int, spinning_friction: float) → None

Set the spinning friction of a link.

Parameters:

  • body (str) – Body unique name.

  • link (int) – Link index in the body.

  • spinning_friction (float) – Spinning friction.

step() → None

Step the simulation.