Source code for stonesoup.sensor.action.dwell_action

import datetime
from copy import copy
from typing import Iterator

import numpy as np

from . import Action, RealNumberActionGenerator
from ...base import Property
from ...functions import mod_bearing
from ...types.angle import Angle, Bearing


[docs] class ChangeDwellAction(Action): """The action of changing the dwell centre of sensors where `dwell_centre` is an :class:`~.ActionableProperty`""" rotation_end_time: datetime.datetime = Property(readonly=True, doc="End time of rotation.") increasing_angle: bool = Property(default=None, readonly=True, doc="Indicated the direction of change in the " "dwell centre angle.")
[docs] def act(self, current_time, timestamp, init_value): """Assumes that duration keeps within the action end time Parameters ---------- current_time: datetime.datetime Current time timestamp: datetime.datetime Modification of attribute ends at this time stamp init_value: Any Current value of the dwell centre Returns ------- Any The new value of the dwell centre""" if self.increasing_angle is None: return init_value if current_time >= self.rotation_end_time: return init_value if timestamp <= self.rotation_end_time: # rotate for duration duration = timestamp - current_time else: # timestamp > rot end time # so rotate then stay duration = self.rotation_end_time - current_time dwell_centre = np.asfarray(copy(init_value)) # in case value is mutable angle_delta = duration.total_seconds() * self.generator.rps * 2 * np.pi if self.increasing_angle: dwell_centre[0, 0] = mod_bearing(dwell_centre[0, 0] + angle_delta) else: dwell_centre[0, 0] = mod_bearing(dwell_centre[0, 0] - angle_delta) return dwell_centre
[docs] class DwellActionsGenerator(RealNumberActionGenerator): """Generates possible actions for changing the dwell centre of a sensor in a given time period.""" owner: object = Property(doc="Object with `timestamp`, `rpm` (revolutions per minute) and " "dwell-centre attributes") resolution: Angle = Property(default=np.radians(1), doc="Resolution of action space") def __init__(self, *args, **kwargs): super().__init__(*args, **kwargs) self.epsilon = Angle(np.radians(1e-6)) @property def default_action(self): return ChangeDwellAction(rotation_end_time=self.end_time, generator=self, end_time=self.end_time, target_value=self.initial_value, increasing_angle=True) def __call__(self, resolution=None, epsilon=None): """ Parameters ---------- resolution : Angle Resolution of yielded action target values epsilon: float Tolerance of equality check in iteration """ if resolution is not None: self.resolution = resolution if epsilon is not None: self.epsilon = epsilon @property def initial_value(self): return Angle(self.current_value[0, 0]) @property def duration(self): return self.end_time - self.start_time @property def rps(self): return self.owner.rpm / 60 @property def angle_delta(self): return Angle(self.duration.total_seconds() * self.rps * 2 * np.pi) @property def min(self): return Angle(self.initial_value - self.angle_delta) @property def max(self): return Angle(self.initial_value + self.angle_delta) def __contains__(self, item): if self.angle_delta >= np.pi: # Left turn and right turn are > 180, so all angles hit return True if isinstance(item, ChangeDwellAction): item = item.target_value if isinstance(item, (float, int)): item = Angle(item) return self.min <= item <= self.max def _end_time_direction(self, angle): """Given a target bearing, should the dwell centre rotate so as to increase its angle value, or decrease? And how long until it reaches the target.""" angle = Angle(angle) if self.initial_value - self.epsilon \ <= angle \ <= self.initial_value + self.epsilon: return self.start_time, None # no rotation, target bearing achieved angle_delta = np.abs(angle - self.initial_value) return ( self.start_time + datetime.timedelta(seconds=angle_delta / (self.rps * 2 * np.pi)), angle > self.initial_value ) def __iter__(self) -> Iterator[ChangeDwellAction]: """Returns ChangeDwellAction types, where the value is a possible value of the [0, 0] element of the dwell centre's state vector.""" current_angle = self.min while current_angle <= self.max + self.epsilon: rot_end_time, increasing = self._end_time_direction(current_angle) yield ChangeDwellAction(rotation_end_time=rot_end_time, generator=self, end_time=self.end_time, target_value=Bearing(current_angle), increasing_angle=increasing) current_angle += self.resolution
[docs] def action_from_value(self, value): """Given a value for dwell centre, what action would achieve that dwell centre value. Parameters ---------- value: Any Dwell centre value for which the action is required. Returns ------- ChangeDwellAction Action which will achieve this dwell centre. """ if isinstance(value, (int, float)): value = Angle(value) elif isinstance(value, Angle): value = value else: raise ValueError("Can only generate action from an Angle/float/int type") if value not in self: return None # Should this raise an error? # Use resolution to reach target value from initial value - does not exceed current_value = previous_value = self.initial_value if value > self.initial_value: while not np.isclose(float(abs(current_value)), float(abs(value)), atol=1e-6): if current_value > value: current_value = previous_value break previous_value = current_value current_value += self.resolution elif value < self.initial_value: while not np.isclose(float(abs(current_value)), float(abs(value)), atol=1e-6): if current_value < value: current_value = previous_value break previous_value = current_value current_value -= self.resolution elif value == self.initial_value: current_value = value else: raise ValueError() target_value = current_value rot_end_time, increasing = self._end_time_direction(target_value) return ChangeDwellAction(rotation_end_time=rot_end_time, generator=self, end_time=self.end_time, target_value=target_value, increasing_angle=increasing)