nyx_space/od/simulator/arc.rs
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/*
Nyx, blazing fast astrodynamics
Copyright (C) 2018-onwards Christopher Rabotin <christopher.rabotin@gmail.com>
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as published
by the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Affero General Public License for more details.
You should have received a copy of the GNU Affero General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
use anise::almanac::Almanac;
use hifitime::{Duration, Epoch, TimeSeries, TimeUnits};
use num::integer::gcd;
use rand::SeedableRng;
use rand_pcg::Pcg64Mcg;
use crate::dynamics::NyxError;
use crate::io::ConfigError;
use crate::md::trajectory::Interpolatable;
use crate::od::msr::TrackingDataArc;
use crate::od::prelude::Strand;
use crate::od::simulator::Cadence;
use crate::od::GroundStation;
use crate::Spacecraft;
use crate::State;
use crate::{linalg::allocator::Allocator, od::TrackingDevice};
use crate::{linalg::DefaultAllocator, md::prelude::Traj};
use std::collections::BTreeMap;
use std::fmt::Display;
use std::marker::PhantomData;
use std::sync::Arc;
use super::{Handoff, TrkConfig};
#[derive(Clone)]
pub struct TrackingArcSim<MsrIn, D>
where
D: TrackingDevice<MsrIn>,
MsrIn: State,
MsrIn: Interpolatable,
DefaultAllocator: Allocator<<MsrIn as State>::Size>
+ Allocator<<MsrIn as State>::Size, <MsrIn as State>::Size>
+ Allocator<<MsrIn as State>::VecLength>,
{
/// Map of devices from their names.
pub devices: BTreeMap<String, D>,
/// Receiver trajectory
pub trajectory: Traj<MsrIn>,
/// Configuration of each device
pub configs: BTreeMap<String, TrkConfig>,
/// Random number generator used for this tracking arc, ensures repeatability
rng: Pcg64Mcg,
/// Greatest common denominator time series that allows this arc to meet all of the conditions.
time_series: TimeSeries,
_msr_in: PhantomData<MsrIn>,
}
impl<MsrIn, D> TrackingArcSim<MsrIn, D>
where
D: TrackingDevice<MsrIn>,
MsrIn: State,
MsrIn: Interpolatable,
DefaultAllocator: Allocator<<MsrIn as State>::Size>
+ Allocator<<MsrIn as State>::Size, <MsrIn as State>::Size>
+ Allocator<<MsrIn as State>::VecLength>,
{
/// Build a new tracking arc simulator using the provided seeded random number generator.
pub fn with_rng(
devices: BTreeMap<String, D>,
trajectory: Traj<MsrIn>,
configs: BTreeMap<String, TrkConfig>,
rng: Pcg64Mcg,
) -> Result<Self, ConfigError> {
// Check that each device has an associated configurations.
// We don't care if there are more configurations than chosen devices.
let mut sampling_rates_ns = Vec::with_capacity(devices.len());
for name in devices.keys() {
if let Some(cfg) = configs.get(name) {
if let Err(e) = cfg.sanity_check() {
warn!("Ignoring device {name}: {e}");
continue;
}
sampling_rates_ns.push(cfg.sampling.truncated_nanoseconds());
} else {
warn!("Ignoring device {name}: no associated tracking configuration",);
continue;
}
}
if sampling_rates_ns.is_empty() {
return Err(ConfigError::InvalidConfig {
msg: "None of the devices are properly configured".to_string(),
});
}
let common_sampling_rate_ns = sampling_rates_ns
.iter()
.fold(sampling_rates_ns[0], |a, &b| gcd(a, b));
// The overall time series is the one going from the start to the end of the trajectory with the smallest time step
// of all the tracking configurations.
let time_series = TimeSeries::inclusive(
trajectory.first().epoch(),
trajectory.last().epoch(),
Duration::from_truncated_nanoseconds(common_sampling_rate_ns),
);
let me = Self {
devices,
trajectory,
configs,
rng,
time_series,
_msr_in: PhantomData,
};
info!("{me}");
Ok(me)
}
/// Build a new tracking arc simulator using the provided seed to initialize the random number generator.
pub fn with_seed(
devices: BTreeMap<String, D>,
trajectory: Traj<MsrIn>,
configs: BTreeMap<String, TrkConfig>,
seed: u64,
) -> Result<Self, ConfigError> {
let rng = Pcg64Mcg::new(seed as u128);
Self::with_rng(devices, trajectory, configs, rng)
}
/// Build a new tracking arc simulator using the system entropy to seed the random number generator.
pub fn new(
devices: BTreeMap<String, D>,
trajectory: Traj<MsrIn>,
configs: BTreeMap<String, TrkConfig>,
) -> Result<Self, ConfigError> {
let rng = Pcg64Mcg::from_entropy();
Self::with_rng(devices, trajectory, configs, rng)
}
/// Generates measurements for the tracking arc using the defined strands
///
/// # Warning
/// This function will return an error if any of the devices defines as a scheduler.
/// You must create the schedule first using `build_schedule` first.
///
/// # Notes
/// Although mutable, this function may be called several times to generate different measurements.
///
/// # Algorithm
/// For each tracking device, and for each strand within that device, sample the trajectory at the sample
/// rate of the tracking device, adding a measurement whenever the spacecraft is visible.
/// Build the measurements as a vector, ordered chronologically.
///
pub fn generate_measurements(
&mut self,
almanac: Arc<Almanac>,
) -> Result<TrackingDataArc, NyxError> {
let mut measurements = BTreeMap::new();
for (name, device) in self.devices.iter_mut() {
if let Some(cfg) = self.configs.get(name) {
if cfg.scheduler.is_some() {
if cfg.strands.is_none() {
return Err(NyxError::CustomError {
msg: format!(
"schedule for {name} must be built before generating measurements"
),
});
} else {
warn!("scheduler for {name} is ignored, using the defined tracking strands instead")
}
}
let init_msr_count = measurements.len();
let tick = Epoch::now().unwrap();
match cfg.strands.as_ref() {
Some(strands) => {
// Strands are defined at this point
'strands: for (ii, strand) in strands.iter().enumerate() {
// Build the time series for this strand, sampling at the correct rate
for epoch in
TimeSeries::inclusive(strand.start, strand.end, cfg.sampling)
{
match device.measure(
epoch,
&self.trajectory,
Some(&mut self.rng),
almanac.clone(),
) {
Ok(msr_opt) => {
if let Some(msr) = msr_opt {
measurements.insert(epoch, msr);
}
}
Err(e) => {
if epoch != strand.end {
warn!(
"Skipping the remaining strand #{ii} ending on {}: {e}",
strand.end
);
}
continue 'strands;
}
}
}
}
info!(
"Simulated {} measurements for {name} for {} tracking strands in {}",
measurements.len() - init_msr_count,
strands.len(),
(Epoch::now().unwrap() - tick).round(1.0_f64.milliseconds())
);
}
None => {
warn!("No tracking strands defined for {name}, skipping");
}
}
}
}
// Build the tracking arc.
let trk_data = TrackingDataArc {
measurements,
source: None,
};
Ok(trk_data)
}
}
impl<MsrIn, D> Display for TrackingArcSim<MsrIn, D>
where
D: TrackingDevice<MsrIn>,
MsrIn: Interpolatable,
DefaultAllocator: Allocator<<MsrIn as State>::Size>
+ Allocator<<MsrIn as State>::Size, <MsrIn as State>::Size>
+ Allocator<<MsrIn as State>::VecLength>,
{
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
write!(
f,
"Tracking Arc Simulator on {} with devices {:?} over {}",
self.trajectory,
self.devices.keys(),
self.time_series
)
}
}
// Literally the same as above, but can't make it generic =(
impl TrackingArcSim<Spacecraft, GroundStation> {
/// Builds the schedule provided the config. Requires the tracker to be a ground station.
///
/// # Algorithm
///
/// 1. For each tracking device:
/// 2. Find when the vehicle trajectory has an elevation greater or equal to zero, and use that as the first start of the first tracking arc for this station
/// 3. Find when the vehicle trajectory has an elevation less than zero (i.e. disappears below the horizon), after that initial epoch
/// 4. Repeat 2, 3 until the end of the trajectory
/// 5. Build each of these as "tracking strands" for this tracking device.
/// 6. Organize all of the built tracking strands chronologically.
/// 7. Iterate through all of the strands:
/// 7.a. if that tracker is marked as `Greedy` and it ends after the start of the next strand, change the start date of the next strand.
/// 7.b. if that tracker is marked as `Eager` and it ends after the start of the next strand, change the end date of the current strand.
pub fn generate_schedule(
&self,
almanac: Arc<Almanac>,
) -> Result<BTreeMap<String, TrkConfig>, NyxError> {
// Consider using find_all via the heuristic
let mut built_cfg = self.configs.clone();
for (name, device) in self.devices.iter() {
if let Some(cfg) = self.configs.get(name) {
if let Some(scheduler) = cfg.scheduler {
info!("Building schedule for {name}");
built_cfg.get_mut(name).unwrap().scheduler = None;
built_cfg.get_mut(name).unwrap().strands = Some(Vec::new());
// Convert the trajectory into the ground station frame.
let traj = self.trajectory.to_frame(device.frame, almanac.clone())?;
match traj.find_arcs(&device, almanac.clone()) {
Err(_) => info!("No measurements from {name}"),
Ok(elevation_arcs) => {
for arc in elevation_arcs {
let strand_start = arc.rise.state.epoch();
let strand_end = arc.fall.state.epoch();
if strand_end - strand_start
< cfg.sampling * i64::from(scheduler.min_samples)
{
info!(
"Too few samples from {name} opportunity from {strand_start} to {strand_end}, discarding strand",
);
continue;
}
let mut strand_range = Strand {
start: strand_start,
end: strand_end,
};
// If there is an alignment, apply it
if let Some(alignment) = scheduler.sample_alignment {
strand_range.start = strand_range.start.round(alignment);
strand_range.end = strand_range.end.round(alignment);
}
if let Cadence::Intermittent { on, off } = scheduler.cadence {
// Check that the next start time is within the allocated time
if let Some(prev_strand) =
built_cfg[name].strands.as_ref().unwrap().last()
{
if prev_strand.end + off > strand_range.start {
// We're turning on the tracking sooner than the schedule allows, so let's fix that.
strand_range.start = prev_strand.end + off;
// Check that we didn't eat into the whole tracking opportunity
if strand_range.start > strand_end {
// Lost this whole opportunity.
info!("Discarding {name} opportunity from {strand_start} to {strand_end} due to cadence {:?}", scheduler.cadence);
continue;
}
}
}
// Check that we aren't tracking for longer than configured
if strand_range.end - strand_range.start > on {
strand_range.end = strand_range.start + on;
}
}
// We've found when the spacecraft is below the horizon, so this is a new strand.
built_cfg
.get_mut(name)
.unwrap()
.strands
.as_mut()
.unwrap()
.push(strand_range);
}
info!(
"Built {} tracking strands for {name}",
built_cfg[name].strands.as_ref().unwrap().len()
);
}
}
}
}
}
// Build all of the strands, remembering which tracker they come from.
let mut cfg_as_vec = Vec::new();
for (name, cfg) in &built_cfg {
if let Some(strands) = &cfg.strands {
for (ii, strand) in strands.iter().enumerate() {
cfg_as_vec.push((name.clone(), ii, *strand));
}
}
}
// Iterate through the strands by chronological order. Cannot use maps because we change types.
cfg_as_vec.sort_by_key(|(_, _, strand)| strand.start);
for (ii, (this_name, this_pos, this_strand)) in
cfg_as_vec.iter().take(cfg_as_vec.len() - 1).enumerate()
{
// Grab the config
if let Some(config) = self.configs[this_name].scheduler.as_ref() {
// Grab the next strand, chronologically
if let Some((next_name, next_pos, next_strand)) = cfg_as_vec.get(ii + 1) {
if config.handoff == Handoff::Greedy && this_strand.end >= next_strand.start {
// Modify the built configurations to change the start time of the next strand because the current one is greedy.
let next_config = built_cfg.get_mut(next_name).unwrap();
let new_start = this_strand.end + next_config.sampling;
next_config.strands.as_mut().unwrap()[*next_pos].start = new_start;
info!(
"{this_name} configured as {:?}, so {next_name} now starts on {new_start}",
config.handoff
);
} else if config.handoff == Handoff::Eager
&& this_strand.end >= next_strand.start
{
let this_config = built_cfg.get_mut(this_name).unwrap();
let new_end = next_strand.start - this_config.sampling;
this_config.strands.as_mut().unwrap()[*this_pos].end = new_end;
info!(
"{this_name} now hands off to {next_name} on {new_end} because it's configured as {:?}",
config.handoff
);
}
} else {
// Reached the end
break;
}
}
}
Ok(built_cfg)
}
/// Sets the schedule to that built in `build_schedule`
pub fn build_schedule(&mut self, almanac: Arc<Almanac>) -> Result<(), NyxError> {
self.configs = self.generate_schedule(almanac)?;
Ok(())
}
}