pydrake.examples

Provides bindings of existing C++ example library code as well as a few pure Python examples.

class pydrake.examples.AcrobotGeometry

Bases: pydrake.systems.framework.LeafSystem

Expresses an AcrobotPlant’s geometry to a SceneGraph.

state→
AcrobotGeometry
→ geometry_pose

This class has no public constructor; instead use the AddToBuilder() static method to create and add it to a DiagramBuilder directly.

__init__(*args, **kwargs)
static AddToBuilder(*args, **kwargs)

Overloaded function.

  1. AddToBuilder(builder: pydrake.systems.framework.DiagramBuilder, acrobot_state_port: pydrake.systems.framework.OutputPort, acrobot_params: pydrake.examples.AcrobotParams, scene_graph: pydrake.geometry.SceneGraph) -> pydrake.examples.AcrobotGeometry

Creates, adds, and connects an AcrobotGeometry system into the given builder. Both the acrobot_state.get_system() and scene_graph systems must have been added to the given builder already.

Parameter acrobot_params:

sets the parameters of the geometry registered with scene_graph.

The scene_graph pointer is not retained by the AcrobotGeometry system. The return value pointer is an alias of the new AcrobotGeometry system that is owned by the builder.

  1. AddToBuilder(builder: pydrake.systems.framework.DiagramBuilder, acrobot_state_port: pydrake.systems.framework.OutputPort, scene_graph: pydrake.geometry.SceneGraph) -> pydrake.examples.AcrobotGeometry

Creates, adds, and connects an AcrobotGeometry system into the given builder. Both the acrobot_state.get_system() and scene_graph systems must have been added to the given builder already.

Acrobot parameters are set to their default values.

The scene_graph pointer is not retained by the AcrobotGeometry system. The return value pointer is an alias of the new AcrobotGeometry system that is owned by the builder.

class pydrake.examples.AcrobotInput

Bases: pydrake.systems.framework.BasicVector

Specializes BasicVector with specific getters and setters.

__init__(self: pydrake.examples.AcrobotInput) → None

Default constructor. Sets all rows to their default value:

  • tau defaults to 0.0 Nm.

set_tau(self: pydrake.examples.AcrobotInput, arg0: float) → None

Setter that matches tau().

tau(self: pydrake.examples.AcrobotInput) → float

Torque at the elbow

Note

tau is expressed in units of Nm.

class pydrake.examples.AcrobotParams

Bases: pydrake.systems.framework.BasicVector

Specializes BasicVector with specific getters and setters.

__init__(self: pydrake.examples.AcrobotParams) → None

Default constructor. Sets all rows to their default value:

  • m1 defaults to 1.0 kg.

  • m2 defaults to 1.0 kg.

  • l1 defaults to 1.0 m.

  • l2 defaults to 2.0 m.

  • lc1 defaults to 0.5 m.

  • lc2 defaults to 1.0 m.

  • Ic1 defaults to 0.083 kg*m^2.

  • Ic2 defaults to 0.33 kg*m^2.

  • b1 defaults to 0.1 kg*m^2/s.

  • b2 defaults to 0.1 kg*m^2/s.

  • gravity defaults to 9.81 m/s^2.

b1(self: pydrake.examples.AcrobotParams) → float

Damping coefficient of the shoulder joint.

Note

b1 is expressed in units of kg*m^2/s.

Note

b1 has a limited domain of [0.0, +Inf].

b2(self: pydrake.examples.AcrobotParams) → float

Damping coefficient of the elbow joint.

Note

b2 is expressed in units of kg*m^2/s.

Note

b2 has a limited domain of [0.0, +Inf].

gravity(self: pydrake.examples.AcrobotParams) → float

Gravitational constant.

Note

gravity is expressed in units of m/s^2.

Note

gravity has a limited domain of [0.0, +Inf].

Ic1(self: pydrake.examples.AcrobotParams) → float

Inertia of link 1 about the center of mass of link 1.

Note

Ic1 is expressed in units of kg*m^2.

Note

Ic1 has a limited domain of [0.0, +Inf].

Ic2(self: pydrake.examples.AcrobotParams) → float

Inertia of link 2 about the center of mass of link 2.

Note

Ic2 is expressed in units of kg*m^2.

Note

Ic2 has a limited domain of [0.0, +Inf].

l1(self: pydrake.examples.AcrobotParams) → float

Length of link 1.

Note

l1 is expressed in units of m.

Note

l1 has a limited domain of [0.0, +Inf].

lc1(self: pydrake.examples.AcrobotParams) → float

Vertical distance from shoulder joint to center of mass of link 1.

Note

lc1 is expressed in units of m.

Note

lc1 has a limited domain of [0.0, +Inf].

lc2(self: pydrake.examples.AcrobotParams) → float

Vertical distance from elbow joint to center of mass of link 1.

Note

lc2 is expressed in units of m.

Note

lc2 has a limited domain of [0.0, +Inf].

m1(self: pydrake.examples.AcrobotParams) → float

Mass of link 1.

Note

m1 is expressed in units of kg.

Note

m1 has a limited domain of [0.0, +Inf].

m2(self: pydrake.examples.AcrobotParams) → float

Mass of link 2.

Note

m2 is expressed in units of kg.

Note

m2 has a limited domain of [0.0, +Inf].

set_b1(self: pydrake.examples.AcrobotParams, arg0: float) → None

Setter that matches b1().

set_b2(self: pydrake.examples.AcrobotParams, arg0: float) → None

Setter that matches b2().

set_gravity(self: pydrake.examples.AcrobotParams, arg0: float) → None

Setter that matches gravity().

set_Ic1(self: pydrake.examples.AcrobotParams, arg0: float) → None

Setter that matches Ic1().

set_Ic2(self: pydrake.examples.AcrobotParams, arg0: float) → None

Setter that matches Ic2().

set_l1(self: pydrake.examples.AcrobotParams, arg0: float) → None

Setter that matches l1().

set_lc1(self: pydrake.examples.AcrobotParams, arg0: float) → None

Setter that matches lc1().

set_lc2(self: pydrake.examples.AcrobotParams, arg0: float) → None

Setter that matches lc2().

set_m1(self: pydrake.examples.AcrobotParams, arg0: float) → None

Setter that matches m1().

set_m2(self: pydrake.examples.AcrobotParams, arg0: float) → None

Setter that matches m2().

class pydrake.examples.AcrobotPlant

Bases: pydrake.systems.framework.LeafSystem

The Acrobot - a canonical underactuated system as described in <a href=”http://underactuated.mit.edu/underactuated.html?chapter=3”>Chapter 3 of Underactuated Robotics</a>.

elbow_torque (optional)→
AcrobotPlant
→ acrobot_state

Note: If the elbow_torque input port is not connected, then the torque is taken to be zero.

__init__(self: pydrake.examples.AcrobotPlant) → None

Constructs the plant. The parameters of the system are stored as Parameters in the Context (see acrobot_params.h).

DynamicsBiasTerm(self: pydrake.examples.AcrobotPlant, arg0: pydrake.systems.framework.Context) → numpy.ndarray[numpy.float64[2, 1]]

Manipulator equation of Acrobot: M(q)q̈ + bias(q,q̇) = B*u.

  • M[2x2] is the mass matrix. - bias[2x1] includes the Coriolis term,

gravity term and the damping term, i.e. bias[2x1] = C(q,v)*v - τ_g(q) + [b1*q̇₁;b2*q̇₂].

get_mutable_parameters(self: pydrake.examples.AcrobotPlant, context: pydrake.systems.framework.Context) → pydrake.examples.AcrobotParams
static get_mutable_state(context: pydrake.systems.framework.Context) → pydrake.examples.AcrobotState
get_parameters(self: pydrake.examples.AcrobotPlant, context: pydrake.systems.framework.Context) → pydrake.examples.AcrobotParams
static get_state(context: pydrake.systems.framework.Context) → pydrake.examples.AcrobotState
MassMatrix(self: pydrake.examples.AcrobotPlant, arg0: pydrake.systems.framework.Context) → numpy.ndarray[numpy.float64[2, 2]]
SetMitAcrobotParameters(self: pydrake.examples.AcrobotPlant, arg0: pydrake.examples.AcrobotParams) → None

Sets the parameters to describe MIT Robot Locomotion Group’s hardware acrobot.

class pydrake.examples.AcrobotSpongController

Bases: pydrake.systems.framework.LeafSystem

The Spong acrobot swing-up controller as described in: Spong, Mark W. “Swing up control of the acrobot.” Robotics and Automation, 1994. Proceedings., 1994 IEEE International Conference on. IEEE, 1994.

Note that the Spong controller works well on the default set of parameters, which Spong used in his paper. In contrast, it is difficult to find a functional set of gains to stabilize the robot about its upright fixed point using the parameters of the physical robot we have in lab.

acrobot_state→
AcrobotSpongController
→ elbow_torque
__init__(self: pydrake.examples.AcrobotSpongController) → None
get_mutable_parameters(self: pydrake.examples.AcrobotSpongController, context: pydrake.systems.framework.Context) → pydrake.examples.SpongControllerParams
get_parameters(self: pydrake.examples.AcrobotSpongController, context: pydrake.systems.framework.Context) → pydrake.examples.SpongControllerParams
class pydrake.examples.AcrobotState

Bases: pydrake.systems.framework.BasicVector

Specializes BasicVector with specific getters and setters.

__init__(self: pydrake.examples.AcrobotState) → None

Default constructor. Sets all rows to their default value:

  • theta1 defaults to 0.0 rad.

  • theta2 defaults to 0.0 rad.

  • theta1dot defaults to 0.0 rad/s.

  • theta2dot defaults to 0.0 rad/s.

set_theta1(self: pydrake.examples.AcrobotState, arg0: float) → None

Setter that matches theta1().

set_theta1dot(self: pydrake.examples.AcrobotState, arg0: float) → None

Setter that matches theta1dot().

set_theta2(self: pydrake.examples.AcrobotState, arg0: float) → None

Setter that matches theta2().

set_theta2dot(self: pydrake.examples.AcrobotState, arg0: float) → None

Setter that matches theta2dot().

theta1(self: pydrake.examples.AcrobotState) → float

The shoulder joint angle

Note

theta1 is expressed in units of rad.

theta1dot(self: pydrake.examples.AcrobotState) → float

The shoulder joint velocity

Note

theta1dot is expressed in units of rad/s.

theta2(self: pydrake.examples.AcrobotState) → float

The elbow joint angle

Note

theta2 is expressed in units of rad.

theta2dot(self: pydrake.examples.AcrobotState) → float

The elbow joint velocity

Note

theta2dot is expressed in units of rad/s.

class pydrake.examples.AcrobotWEncoder

Bases: pydrake.systems.framework.Diagram

Constructs the Acrobot with (only) encoder outputs.

elbow_torque→
AcrobotWEncoder
→ measured_joint_positions
→ acrobot_state

The acrobot_state output port is present only if the construction parameter acrobot_state_as_second_output is true.

__init__(self: pydrake.examples.AcrobotWEncoder, acrobot_state_as_second_output: bool = False) → None
acrobot_plant(self: pydrake.examples.AcrobotWEncoder) → pydrake.examples.AcrobotPlant
get_mutable_acrobot_state(self: pydrake.examples.AcrobotWEncoder, context: pydrake.systems.framework.Context) → pydrake.examples.AcrobotState
class pydrake.examples.CompassGait

Bases: pydrake.systems.framework.LeafSystem

Dynamical representation of the idealized hybrid dynamics of a “compass gait”, as described in http://underactuated.mit.edu/underactuated.html?chapter=simple_legs . This implementation has two additional state variables that are not required in the mathematical model:

  • a discrete state for the position of the stance toe along the ramp

  • a Boolean indicator for “left support” (true when the stance leg is the left leg).

These are helpful for outputting the floating-base model coordinate, e.g. for visualization.

Note

This model only supports walking downhill on the ramp, because that restriction enables a clean / numerically robust implementation of the foot collision witness function that avoids fall detection on the “foot scuffing” collision.

hip_torque (optional)→
CompassGait
→ minimal_state
→ floating_base_state

Continuous States: stance, swing, stancedot, swingdot.

Discrete State: stance toe position.

Abstract State: left support indicator.

Note: If the hip_torque input port is not connected, then the torque is taken to be zero.

__init__(self: pydrake.examples.CompassGait) → None

Constructs the plant.

get_floating_base_state_output_port(self: pydrake.examples.CompassGait) → pydrake.systems.framework.OutputPort

Returns reference to the output port that provides the state in the floating-base coordinates (described via left leg xyz & rpy + hip angle + derivatives).

get_minimal_state_output_port(self: pydrake.examples.CompassGait) → pydrake.systems.framework.OutputPort

Returns reference to the output port that publishes only [theta_stance, theta_swing, thetatdot_stance, thetadot_swing].

class pydrake.examples.CompassGaitContinuousState

Bases: pydrake.systems.framework.BasicVector

Specializes BasicVector with specific getters and setters.

__init__(self: pydrake.examples.CompassGaitContinuousState) → None

Default constructor. Sets all rows to their default value:

  • stance defaults to 0.0 radians.

  • swing defaults to 0.0 radians.

  • stancedot defaults to 0.0 rad/sec.

  • swingdot defaults to 0.0 rad/sec.

set_stance(self: pydrake.examples.CompassGaitContinuousState, arg0: float) → None

Setter that matches stance().

set_stancedot(self: pydrake.examples.CompassGaitContinuousState, arg0: float) → None

Setter that matches stancedot().

set_swing(self: pydrake.examples.CompassGaitContinuousState, arg0: float) → None

Setter that matches swing().

set_swingdot(self: pydrake.examples.CompassGaitContinuousState, arg0: float) → None

Setter that matches swingdot().

stance(self: pydrake.examples.CompassGaitContinuousState) → float

The orientation of the stance leg, measured clockwise from the vertical axis.

Note

stance is expressed in units of radians.

stancedot(self: pydrake.examples.CompassGaitContinuousState) → float

The angular velocity of the stance leg.

Note

stancedot is expressed in units of rad/sec.

swing(self: pydrake.examples.CompassGaitContinuousState) → float

The orientation of the swing leg, measured clockwise from the vertical axis.

Note

swing is expressed in units of radians.

swingdot(self: pydrake.examples.CompassGaitContinuousState) → float

The angular velocity of the swing leg.

Note

swingdot is expressed in units of rad/sec.

class pydrake.examples.CompassGaitGeometry

Bases: pydrake.systems.framework.LeafSystem

Expresses a CompassGait’s geometry to a SceneGraph.

floating_base_state→
CompassGaitGeometry
→ geometry_pose

This class has no public constructor; instead use the AddToBuilder() static method to create and add it to a DiagramBuilder directly.

__init__(*args, **kwargs)
static AddToBuilder(*args, **kwargs)

Overloaded function.

  1. AddToBuilder(builder: pydrake.systems.framework.DiagramBuilder, floating_base_state_port: pydrake.systems.framework.OutputPort, compass_gait_params: pydrake.examples.CompassGaitParams, scene_graph: pydrake.geometry.SceneGraph) -> pydrake.examples.CompassGaitGeometry

Creates, adds, and connects a CompassGaitGeometry system into the given builder. Both the floating_base_state_port.get_system() and scene_graph systems must have been added to the given builder already. The compass_gait_params sets the parameters of the geometry registered with scene_graph; the visualization changes based on the leg length and the ration of leg mass to hip mass (the leg mass sphere is scaled assuming a constant density).

The scene_graph pointer is not retained by the CompassGaitGeometry system. The return value pointer is an alias of the new CompassGaitGeometry system that is owned by the builder.

  1. AddToBuilder(builder: pydrake.systems.framework.DiagramBuilder, floating_base_state_port: pydrake.systems.framework.OutputPort, scene_graph: pydrake.geometry.SceneGraph) -> pydrake.examples.CompassGaitGeometry

Creates, adds, and connects a CompassGaitGeometry system into the given builder. Both the floating_base_state_port.get_system() and scene_graph systems must have been added to the given builder already. CompassGaitParams are set to their default values.

The scene_graph pointer is not retained by the CompassGaitGeometry system. The return value pointer is an alias of the new CompassGaitGeometry system that is owned by the builder.

class pydrake.examples.CompassGaitParams

Bases: pydrake.systems.framework.BasicVector

Specializes BasicVector with specific getters and setters.

__init__(self: pydrake.examples.CompassGaitParams) → None

Default constructor. Sets all rows to their default value:

  • mass_hip defaults to 10.0 kg.

  • mass_leg defaults to 5.0 kg.

  • length_leg defaults to 1.0 m.

  • center_of_mass_leg defaults to 0.5 m.

  • gravity defaults to 9.81 m/s^2.

  • slope defaults to 0.0525 radians.

center_of_mass_leg(self: pydrake.examples.CompassGaitParams) → float

Distance from the hip to the center of mass of each leg.

Note

center_of_mass_leg is expressed in units of m.

Note

center_of_mass_leg has a limited domain of [0.0, +Inf].

gravity(self: pydrake.examples.CompassGaitParams) → float

An approximate value for gravitational acceleration.

Note

gravity is expressed in units of m/s^2.

Note

gravity has a limited domain of [0.0, +Inf].

length_leg(self: pydrake.examples.CompassGaitParams) → float

The length of each leg.

Note

length_leg is expressed in units of m.

Note

length_leg has a limited domain of [0.0, +Inf].

mass_hip(self: pydrake.examples.CompassGaitParams) → float

Point mass at the hip.

Note

mass_hip is expressed in units of kg.

Note

mass_hip has a limited domain of [0.0, +Inf].

mass_leg(self: pydrake.examples.CompassGaitParams) → float

Mass of each leg (modeled as a point mass at the center of mass).

Note

mass_leg is expressed in units of kg.

Note

mass_leg has a limited domain of [0.0, +Inf].

set_center_of_mass_leg(self: pydrake.examples.CompassGaitParams, arg0: float) → None

Setter that matches center_of_mass_leg().

set_gravity(self: pydrake.examples.CompassGaitParams, arg0: float) → None

Setter that matches gravity().

set_length_leg(self: pydrake.examples.CompassGaitParams, arg0: float) → None

Setter that matches length_leg().

set_mass_hip(self: pydrake.examples.CompassGaitParams, arg0: float) → None

Setter that matches mass_hip().

set_mass_leg(self: pydrake.examples.CompassGaitParams, arg0: float) → None

Setter that matches mass_leg().

set_slope(self: pydrake.examples.CompassGaitParams, arg0: float) → None

Setter that matches slope().

slope(self: pydrake.examples.CompassGaitParams) → float

The angle of the ramp on which the compass gait is walking. Must have 0 <= slope < PI/2 so that forward == downhill (an assumption used in the foot collision witness function).

Note

slope is expressed in units of radians.

Note

slope has a limited domain of [0.0, 1.5707].

class pydrake.examples.PendulumGeometry

Bases: pydrake.systems.framework.LeafSystem

Expresses a PendulumPlants’s geometry to a SceneGraph.

state→
PendulumGeometry
→ geometry_pose

This class has no public constructor; instead use the AddToBuilder() static method to create and add it to a DiagramBuilder directly.

__init__(*args, **kwargs)
static AddToBuilder(builder: pydrake.systems.framework.DiagramBuilder, pendulum_state_port: pydrake.systems.framework.OutputPort, scene_graph: pydrake.geometry.SceneGraph) → pydrake.examples.PendulumGeometry

Creates, adds, and connects a PendulumGeometry system into the given builder. Both the pendulum_state.get_system() and scene_graph systems must have been added to the given builder already.

The scene_graph pointer is not retained by the PendulumGeometry system. The return value pointer is an alias of the new PendulumGeometry system that is owned by the builder.

class pydrake.examples.PendulumInput

Bases: pydrake.systems.framework.BasicVector

Specializes BasicVector with specific getters and setters.

__init__(self: pydrake.examples.PendulumInput) → None

Default constructor. Sets all rows to their default value:

  • tau defaults to 0.0 Newton-meters.

set_tau(self: pydrake.examples.PendulumInput, tau: float) → None

Setter that matches tau().

tau(self: pydrake.examples.PendulumInput) → float

Torque at the joint.

Note

tau is expressed in units of Newton-meters.

with_tau(self: pydrake.examples.PendulumInput, tau: float) → pydrake.examples.PendulumInput

Fluent setter that matches tau(). Returns a copy of this with tau set to a new value.

class pydrake.examples.PendulumParams

Bases: pydrake.systems.framework.BasicVector

Specializes BasicVector with specific getters and setters.

__init__(self: pydrake.examples.PendulumParams) → None

Default constructor. Sets all rows to their default value:

  • mass defaults to 1.0 kg.

  • length defaults to 0.5 m.

  • damping defaults to 0.1 kg m^2/s.

  • gravity defaults to 9.81 m/s^2.

damping(self: pydrake.examples.PendulumParams) → float

The damping friction coefficient relating angular velocity to torque.

Note

damping is expressed in units of kg m^2/s.

Note

damping has a limited domain of [0.0, +Inf].

gravity(self: pydrake.examples.PendulumParams) → float

An approximate value for gravitational acceleration.

Note

gravity is expressed in units of m/s^2.

Note

gravity has a limited domain of [0.0, +Inf].

length(self: pydrake.examples.PendulumParams) → float

The length of the pendulum arm.

Note

length is expressed in units of m.

Note

length has a limited domain of [0.0, +Inf].

mass(self: pydrake.examples.PendulumParams) → float

The simple pendulum has a single point mass at the end of the arm.

Note

mass is expressed in units of kg.

Note

mass has a limited domain of [0.0, +Inf].

set_damping(self: pydrake.examples.PendulumParams, damping: float) → None

Setter that matches damping().

set_gravity(self: pydrake.examples.PendulumParams, gravity: float) → None

Setter that matches gravity().

set_length(self: pydrake.examples.PendulumParams, length: float) → None

Setter that matches length().

set_mass(self: pydrake.examples.PendulumParams, mass: float) → None

Setter that matches mass().

with_damping(self: pydrake.examples.PendulumParams, damping: float) → pydrake.examples.PendulumParams

Fluent setter that matches damping(). Returns a copy of this with damping set to a new value.

with_gravity(self: pydrake.examples.PendulumParams, gravity: float) → pydrake.examples.PendulumParams

Fluent setter that matches gravity(). Returns a copy of this with gravity set to a new value.

with_length(self: pydrake.examples.PendulumParams, length: float) → pydrake.examples.PendulumParams

Fluent setter that matches length(). Returns a copy of this with length set to a new value.

with_mass(self: pydrake.examples.PendulumParams, mass: float) → pydrake.examples.PendulumParams

Fluent setter that matches mass(). Returns a copy of this with mass set to a new value.

class pydrake.examples.PendulumPlant

Bases: pydrake.systems.framework.LeafSystem

A model of a simple pendulum

\[ml^2 \ddot\theta + b\dot\theta + mgl\sin\theta = \tau\]

name: PendulumPlant input_ports: - tau (optional) output_ports: - state

Note: If the tau input port is not connected, then the torque is taken to be zero.

__init__(self: pydrake.examples.PendulumPlant) → None

Constructs a default plant.

get_mutable_parameters(self: pydrake.examples.PendulumPlant, context: pydrake.systems.framework.Context) → pydrake.examples.PendulumParams
static get_mutable_state(context: pydrake.systems.framework.Context) → pydrake.examples.PendulumState
get_parameters(self: pydrake.examples.PendulumPlant, context: pydrake.systems.framework.Context) → pydrake.examples.PendulumParams
static get_state(context: pydrake.systems.framework.Context) → pydrake.examples.PendulumState
get_state_output_port(self: pydrake.examples.PendulumPlant) → pydrake.systems.framework.OutputPort

Returns the port to output state.

class pydrake.examples.PendulumState

Bases: pydrake.systems.framework.BasicVector

Specializes BasicVector with specific getters and setters.

__init__(self: pydrake.examples.PendulumState) → None

Default constructor. Sets all rows to their default value:

  • theta defaults to 0.0 radians.

  • thetadot defaults to 0.0 radians/sec.

set_theta(self: pydrake.examples.PendulumState, theta: float) → None

Setter that matches theta().

set_thetadot(self: pydrake.examples.PendulumState, thetadot: float) → None

Setter that matches thetadot().

theta(self: pydrake.examples.PendulumState) → float

The angle of the pendulum.

Note

theta is expressed in units of radians.

thetadot(self: pydrake.examples.PendulumState) → float

The angular velocity of the pendulum.

Note

thetadot is expressed in units of radians/sec.

with_theta(self: pydrake.examples.PendulumState, theta: float) → pydrake.examples.PendulumState

Fluent setter that matches theta(). Returns a copy of this with theta set to a new value.

with_thetadot(self: pydrake.examples.PendulumState, thetadot: float) → pydrake.examples.PendulumState

Fluent setter that matches thetadot(). Returns a copy of this with thetadot set to a new value.

class pydrake.examples.QuadrotorGeometry

Bases: pydrake.systems.framework.LeafSystem

Expresses a QuadrotorPlant’s geometry to a SceneGraph.

state→
QuadrotorGeometry
→ geometry_pose

This class has no public constructor; instead use the AddToBuilder() static method to create and add it to a DiagramBuilder directly.

__init__(*args, **kwargs)
static AddToBuilder(builder: pydrake.systems.framework.DiagramBuilder, quadrotor_state_port: pydrake.systems.framework.OutputPort, scene_graph: pydrake.geometry.SceneGraph) → pydrake.examples.QuadrotorGeometry

Creates, adds, and connects a QuadrotorGeometry system into the given builder. Both the quadrotor_state.get_system() and scene_graph systems must have been added to the given builder already.

The scene_graph pointer is not retained by the QuadrotorGeometry system. The return value pointer is an alias of the new QuadrotorGeometry system that is owned by the builder.

get_frame_id(self: pydrake.examples.QuadrotorGeometry) → pydrake.geometry.FrameId

Returns the frame of the geometry registered with a SceneGraph. This can be useful, e.g., if one would like to add a camera to the quadrotor.

class pydrake.examples.QuadrotorPlant

Bases: pydrake.systems.framework.LeafSystem

The Quadrotor - an underactuated aerial vehicle. This version of the Quadrotor is implemented to match the dynamics of the plant specified in the package://drake_models/skydio_2/quadrotor.urdf model file.

propeller_force (optional)→
QuadrotorPlant
→ state

Note: If the propeller_force input port is not connected, then the force is taken to be zero.

__init__(*args, **kwargs)

Overloaded function.

  1. __init__(self: pydrake.examples.QuadrotorPlant) -> None

  2. __init__(self: pydrake.examples.QuadrotorPlant, m_arg: float, L_arg: float, I_arg: numpy.ndarray[numpy.float64[3, 3]], kF_arg: float, kM_arg: float) -> None

force_constant(self: pydrake.examples.QuadrotorPlant) → float
g(self: pydrake.examples.QuadrotorPlant) → float
inertia(self: pydrake.examples.QuadrotorPlant) → numpy.ndarray[numpy.float64[3, 3]]
length(self: pydrake.examples.QuadrotorPlant) → float
m(self: pydrake.examples.QuadrotorPlant) → float
moment_constant(self: pydrake.examples.QuadrotorPlant) → float
class pydrake.examples.RimlessWheel

Bases: pydrake.systems.framework.LeafSystem

Dynamical representation of the idealized hybrid dynamics of a “rimless wheel”, as described in http://underactuated.mit.edu/underactuated.html?chapter=simple_legs In addition, this model has two additional (discrete) state variables that are not required in the mathematical model:

  • the position of the stance toe along the ramp (helpful for outputting a floating-base model coordinate, e.g. for visualization),

  • a boolean indicator for “double support” (to avoid the numerical challenges of simulation around the Zeno phenomenon at the standing fixed point).

RimlessWheel
→ minimal_state
→ floating_base_state

Continuous States: theta, thetadot (emitted at minimal_state port). Discrete States: stance toe position (emitted at floating_base_state port), double support indicator. Parameters: mass, length, number of spokes, etc, are all set as Context parameters using RimlessWheelParams.

__init__(self: pydrake.examples.RimlessWheel) → None

Constructs the plant.

static calc_alpha(params: pydrake.examples.RimlessWheelParams) → float

Alpha is half the interleg angle, and is used frequently.

get_floating_base_state_output_port(self: pydrake.examples.RimlessWheel) → pydrake.systems.framework.OutputPort

Returns reference to the output port that provides a 12 dimensional state (FloatingBaseType::kRollPitchYaw positions then velocities). This is useful, e.g., for visualization. θ of the rimless wheel is the pitch of the floating base (rotation around global y), and downhill moves toward positive x. As always, we use vehicle coordinates (x-y on the ground, z is up).

get_minimal_state_output_port(self: pydrake.examples.RimlessWheel) → pydrake.systems.framework.OutputPort

Return reference to the output port that publishes only [theta, thetatdot].

class pydrake.examples.RimlessWheelContinuousState

Bases: pydrake.systems.framework.BasicVector

Specializes BasicVector with specific getters and setters.

__init__(self: pydrake.examples.RimlessWheelContinuousState) → None

Default constructor. Sets all rows to their default value:

  • theta defaults to 0.0 radians.

  • thetadot defaults to 0.0 rad/sec.

set_theta(self: pydrake.examples.RimlessWheelContinuousState, arg0: float) → None

Setter that matches theta().

set_thetadot(self: pydrake.examples.RimlessWheelContinuousState, arg0: float) → None

Setter that matches thetadot().

theta(self: pydrake.examples.RimlessWheelContinuousState) → float

The orientation of the stance leg, measured clockwise from the vertical axis.

Note

theta is expressed in units of radians.

thetadot(self: pydrake.examples.RimlessWheelContinuousState) → float

The angular velocity of the stance leg.

Note

thetadot is expressed in units of rad/sec.

class pydrake.examples.RimlessWheelGeometry

Bases: pydrake.systems.framework.LeafSystem

Expresses a RimlessWheel’s geometry to a SceneGraph.

floating_base_state→
RimlessWheelGeometry
→ geometry_pose

This class has no public constructor; instead use the AddToBuilder() static method to create and add it to a DiagramBuilder directly.

__init__(*args, **kwargs)
static AddToBuilder(*args, **kwargs)

Overloaded function.

  1. AddToBuilder(builder: pydrake.systems.framework.DiagramBuilder, floating_base_state_port: pydrake.systems.framework.OutputPort, rimless_wheel_params: pydrake.examples.RimlessWheelParams, scene_graph: pydrake.geometry.SceneGraph) -> pydrake.examples.RimlessWheelGeometry

Creates, adds, and connects a RimlessWheelGeometry system into the given builder. Both the floating_base_state_port.get_system() and scene_graph systems must have been added to the given builder already. The rimless_wheel_params sets the parameters of the geometry registered with scene_graph.

The scene_graph pointer is not retained by the RimlessWheelGeometry system. The return value pointer is an alias of the new RimlessWheelGeometry system that is owned by the builder.

  1. AddToBuilder(builder: pydrake.systems.framework.DiagramBuilder, floating_base_state_port: pydrake.systems.framework.OutputPort, scene_graph: pydrake.geometry.SceneGraph) -> pydrake.examples.RimlessWheelGeometry

Creates, adds, and connects a RimlessWheelGeometry system into the given builder. Both the floating_base_state_port.get_system() and scene_graph systems must have been added to the given builder already. RimlessWheelParams are set to their default values.

The scene_graph pointer is not retained by the RimlessWheelGeometry system. The return value pointer is an alias of the new RimlessWheelGeometry system that is owned by the builder.

class pydrake.examples.RimlessWheelParams

Bases: pydrake.systems.framework.BasicVector

Specializes BasicVector with specific getters and setters.

__init__(self: pydrake.examples.RimlessWheelParams) → None

Default constructor. Sets all rows to their default value:

  • mass defaults to 1.0 kg.

  • length defaults to 1.0 m.

  • gravity defaults to 9.81 m/s^2.

  • number_of_spokes defaults to 8 integer.

  • slope defaults to 0.08 radians.

gravity(self: pydrake.examples.RimlessWheelParams) → float

An approximate value for gravitational acceleration.

Note

gravity is expressed in units of m/s^2.

Note

gravity has a limited domain of [0.0, +Inf].

length(self: pydrake.examples.RimlessWheelParams) → float

The length of each spoke.

Note

length is expressed in units of m.

Note

length has a limited domain of [0.0, +Inf].

mass(self: pydrake.examples.RimlessWheelParams) → float

The rimless wheel has a single point mass at the hub.

Note

mass is expressed in units of kg.

Note

mass has a limited domain of [0.0, +Inf].

number_of_spokes(self: pydrake.examples.RimlessWheelParams) → float

Total number of spokes on the wheel

Note

number_of_spokes is expressed in units of integer.

Note

number_of_spokes has a limited domain of [4, +Inf].

set_gravity(self: pydrake.examples.RimlessWheelParams, arg0: float) → None

Setter that matches gravity().

set_length(self: pydrake.examples.RimlessWheelParams, arg0: float) → None

Setter that matches length().

set_mass(self: pydrake.examples.RimlessWheelParams, arg0: float) → None

Setter that matches mass().

set_number_of_spokes(self: pydrake.examples.RimlessWheelParams, arg0: float) → None

Setter that matches number_of_spokes().

set_slope(self: pydrake.examples.RimlessWheelParams, arg0: float) → None

Setter that matches slope().

slope(self: pydrake.examples.RimlessWheelParams) → float

The angle of the ramp on which the rimless wheel is walking.

Note

slope is expressed in units of radians.

class pydrake.examples.SpongControllerParams

Bases: pydrake.systems.framework.BasicVector

Specializes BasicVector with specific getters and setters.

__init__(self: pydrake.examples.SpongControllerParams) → None

Default constructor. Sets all rows to their default value:

  • k_e defaults to 5.0 s.

  • k_p defaults to 50.0 s^-2.

  • k_d defaults to 5.0 s^-1.

  • balancing_threshold defaults to 1e3 None.

balancing_threshold(self: pydrake.examples.SpongControllerParams) → float

Cost value at which to switch from swing up to balancing.

Note

balancing_threshold is expressed in units of None.

Note

balancing_threshold has a limited domain of [0.0, +Inf].

k_d(self: pydrake.examples.SpongControllerParams) → float

Partial feedback linearization derivative gain.

Note

k_d is expressed in units of s^-1.

Note

k_d has a limited domain of [0.0, +Inf].

k_e(self: pydrake.examples.SpongControllerParams) → float

Energy shaping gain.

Note

k_e is expressed in units of s.

Note

k_e has a limited domain of [0.0, +Inf].

k_p(self: pydrake.examples.SpongControllerParams) → float

Partial feedback linearization proportional gain.

Note

k_p is expressed in units of s^-2.

Note

k_p has a limited domain of [0.0, +Inf].

set_balancing_threshold(self: pydrake.examples.SpongControllerParams, arg0: float) → None

Setter that matches balancing_threshold().

set_k_d(self: pydrake.examples.SpongControllerParams, arg0: float) → None

Setter that matches k_d().

set_k_e(self: pydrake.examples.SpongControllerParams, arg0: float) → None

Setter that matches k_e().

set_k_p(self: pydrake.examples.SpongControllerParams, arg0: float) → None

Setter that matches k_p().

pydrake.examples.StabilizingLQRController(quadrotor_plant: pydrake.examples.QuadrotorPlant, nominal_position: numpy.ndarray[numpy.float64[3, 1]]) → pydrake.systems.primitives.AffineSystem

Generates an LQR controller to move to nominal_position. Internally computes the nominal input corresponding to a hover at position x0.

See also

systems::LinearQuadraticRegulator.

class pydrake.examples.VanDerPolOscillator

Bases: pydrake.systems.framework.LeafSystem

van der Pol oscillator

The van der Pol oscillator, governed by the following equations: q̈ + μ(q² - 1)q̇ + q = 0, μ > 0 y₀ = q y₁ = [q,q̇]’ is a canonical example of a nonlinear system that exhibits a limit cycle stability. As such it serves as an important for examining nonlinear stability and stochastic stability.

(Examples involving region of attraction analysis and analyzing the stationary distribution of the oscillator under process noise are coming soon).

VanDerPolOscillator
→ y0
→ y1
__init__(self: pydrake.examples.VanDerPolOscillator) → None

Constructs a default oscillator.

static CalcLimitCycle() → numpy.ndarray[numpy.float64[2, n]]

Returns a 2-row matrix containing the result of simulating the oscillator with the default mu=1 from (approximately) one point on the limit cycle for (approximately) one period. The first row is q, and the second row is q̇.

get_full_state_output_port(self: pydrake.examples.VanDerPolOscillator) → pydrake.systems.framework.OutputPort

Returns the output port containing the full state. This is provided primarily as a tool for debugging/visualization.

get_position_output_port(self: pydrake.examples.VanDerPolOscillator) → pydrake.systems.framework.OutputPort

Returns the output port containing the output configuration (only).