Base Class

class Kinematics

Abstract Kinematics type.

A kinematics is used to

• validated twist in the agent’s frame as feasible

• convert between wheel speeds and body twist

• returns maximal linear and angular speed

• returns the number of degrees of freedom

Negative speed means unconstrained.

__init__(max_speed: float = float('inf'), max_angular_speed: float = float('inf')) → None

dof() → int

Returns the degrees of freedom (between 0 and 3 for planar rigid body kinematics)

Returns:

The number of degrees of freedom.

dump() → str

Dumps the object to a YAML-string.

Returns:

The YAML representation

Return type:

str

feasible(twist: navground.core.Twist2) → navground.core.Twist2

Computes the nearest feasible twist to a desired twist.

Parameters:

twist – The desired twist

Returns:

The same desired twist if feasible else the nearest feasible value. How this is defined depends on the concrete sub-class.

feasible_from_current(twist: navground.core.Twist2, current: navground.core.Twist2, time_step: float) → navground.core.Twist2

Computes the nearest feasible twist to a desired twist, taking into account dynamic constraints

Parameters:

• twist – The desired twist

• current – The current twist

• time_step – The time step to reach the desired twist

Returns:

The same desired twist if feasible else the nearest feasible value. How this is defined depends on the concrete sub-class.

get(name: str) → bool | int | float | str | Vector2 | list[bool] | list[int] | list[float] | list[str] | list[Vector2]

Gets the value of the specified property.

Parameters:

name – The name of the property

Raise:

std::runtime_error A runtime error if no property is found.

Returns:

The value of the property

get_max_angular_speed() → float

Gets the maximal angular speed.

Returns:

The maximal angular speed.

get_max_speed() → float

Gets the maximal speed.

Returns:

The maximal speed.

get_property_type_name(name: str) → str

Gets the type of a property.

Parameters:

name – The name of the property

Returns:

The property type name or an empty string if the property is not defined.

has(name: str) → bool

Checks whether a property exists.

Parameters:

name – The name of the property

Returns:

True if the property exists

static has_type(name: str) → bool

Check whether a type name has been registered.

Parameters:

type – The associated type name.

Returns:

True if the type name has been registered.

is_wheeled() → bool

Returns whether the kinematics has wheels.

Returns:

True if wheeled, False otherwise.

static load(value: str) → object

Load a kinematics from a YAML string.

Parameters:

value – the YAML string.

Returns:

The loaded kinematics or None if loading fails.

Return type:

Kinematics| None

static make_type(name: str) → object

Create an object of a sub-class selected by name.

Parameters:

type – The associated type name.

Returns:

An object of a registered sub-class or None in case the desired name is not found.

static register_schema() → object

Returns the json-schema that includes registered components.

Returns:

“anyOf” json-schema of all registered components.

Return type:

dict[str, typing.Any]

static schema(reference_register_schema: bool = True, type: str | None = None) → object

Returns the json-schema of a component

Returns an empty dictionary if a not registered type is requested.

Parameters:

• reference_register_schema – Whether to reference registered components schema in the base class schema.

• type (str) – An optional registered type. If not specified, it returns the schema of the base class.

Returns:

A json-schema of the registered class

Return type:

dict[str, typing.Any]

set(name: str, value: bool | int | float | str | Vector2 | list[bool] | list[int] | list[float] | list[str] | list[Vector2]) → None

Set the value of a named property. Fails silently if no property can be found or if the value has a non-compatible type.

Parameters:

• name – The name of the property

• value – The desired value for the property

property max_angular_speed

Type:

float

The maximal angular speed.

property max_speed

Type:

float

The maximal speed.

property properties

Type:

dict[str, navground.core.Property]

The registered properties

property type

Type:

str

The name associated to the type of an object