class LedgerFilter:
"""Records filter inputs and makes available an event triggered buffer. """
def __init__(self,
num_ownship_states,
x0,
P0,
delta_codebook_table,
delta_multiplier,
is_main_filter,
asset2id,
my_name,
default_meas_variance,
common_filter=None):
"""Constructor
Arguments:
num_ownship_states {int} -- Number of ownship states for each asset
x0 {np.ndarray} -- initial states
P0 {np.ndarray} -- initial uncertainty
delta_codebook_table {dict} -- Hash thatp stores delta trigger for each measurement type. Str(meas type) -> float (delta trigger)
delta_multiplier {float} -- Delta trigger constant multiplier for this filter
is_main_filter {bool} -- Is this filter a common or main filter (if main the meas buffer does not matter)
asset2id {dict} -- Hash to get the id number of an asset from the string name
my_name {str} -- Name to loopkup in asset2id the current asset's ID#
default_meas_variance {dict} -- Hash to get measurement variance
common_filter {dict} -- asset to common ETFilter
"""
if delta_multiplier <= 0:
raise ValueError("Delta Multiplier must be greater than 0")
self.num_ownship_states = num_ownship_states
self.delta_codebook_table = delta_codebook_table
self.delta_multiplier = delta_multiplier
self.is_main_filter = is_main_filter
if self.is_main_filter:
assert common_filter is not None
self.filter = ETFilter_Main(asset2id[my_name], num_ownship_states,
3, x0, P0, True, {"": common_filter})
else:
self.filter = ETFilter(asset2id[my_name], num_ownship_states, 3,
x0, P0, True)
self.original_filter = deepcopy(self.filter)
self.asset2id = asset2id
self.my_name = my_name
self.default_meas_variance = default_meas_variance
# Initialize ledger with first update
self.ledger = {}
self._add_block()
self.explicit_count = 0
self.meas_types_received = []
def change_common_filter(self, common_filter):
self.filter.common_filters = {"": common_filter}
def _add_block(self):
next_step = len(self.ledger) + 1
self.ledger[next_step] = {
"meas": [],
"time": None,
"u": None,
"Q": None,
"nav_mean": None,
"nav_cov": None,
"x_hat_prior": deepcopy(self.filter.x_hat),
"P_prior": deepcopy(self.filter.P)
}
def _get_meas_ledger_index(self, meas_time):
for i in range(1, len(self.ledger) + 1):
ledger_time = self.ledger[i]["time"]
if ledger_time is None:
return i
elif meas_time < ledger_time:
return i
def _is_shareable(self, src_asset, meas_type):
if not self.is_main_filter and src_asset == self.my_name:
for m in MEASUREMENT_TYPES_SHARED:
if m in meas_type:
return True
return False
def add_meas(self, ros_meas, output=False):
"""Adds and records a measurement to the filter
Arguments:
ros_meas {etddf.Measurement.msg} -- The measurement in ROS form
"""
msg_id = self._get_meas_identifier(ros_meas)
# Main filter fuses all measurements
if self.is_main_filter:
pass
elif ros_meas.src_asset != self.my_name:
pass
elif self._is_shareable(ros_meas.src_asset, ros_meas.meas_type):
pass
elif msg_id in self.meas_types_received:
return
else: # Don't fuse (e.g. depth, sonar_z)
return -1
self.meas_types_received.append(msg_id)
ledger_ind = self._get_meas_ledger_index(ros_meas.stamp)
# Check for Event-Triggering
if self._is_shareable(ros_meas.src_asset, ros_meas.meas_type):
if "implicit" not in ros_meas.meas_type:
src_id = self.asset2id[ros_meas.src_asset]
measured_id = self.asset2id[ros_meas.measured_asset]
ros_meas.et_delta = self._get_meas_et_delta(ros_meas.meas_type)
meas = get_internal_meas_from_ros_meas(ros_meas, src_id,
measured_id)
implicit, innovation = self.filter.check_implicit(meas)
if implicit:
ros_meas.meas_type += "_implicit"
# print("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ IMPLICIT @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@")
# print(ros_meas)
# print(vars(meas))
# print(self.filter.x_hat)
else:
self.explicit_count += 1
if output:
expected = meas.data - innovation
meas_id = self._get_meas_identifier(ros_meas)
last_update_time = self.ledger[len(self.ledger) -
1]["time"]
# print("Explicit {} {} : expected: {}, got: {}".format(last_update_time.to_sec(), meas_id, expected, meas.data))
# print(self.meas_types_received)
# print(self.filter.x_hat.T)
# print("Explicit #{} {} : {}".format(self.explicit_count, self.delta_multiplier, ros_meas.meas_type))
# print(ros_meas)
# print(vars(meas))
# print(self.filter.x_hat)
# Append to the ledger
self.ledger[ledger_ind]["meas"].append(ros_meas)
return ledger_ind
@staticmethod
def run_covariance_intersection(xa, Pa, xb, Pb):
"""Runs covariance intersection on the two estimates A and B
Arguments:
xa {np.ndarray} -- mean of A
Pa {np.ndarray} -- covariance of A
xb {np.ndarray} -- mean of B
Pb {np.ndarray} -- covariance of B
Returns:
c_bar {np.ndarray} -- intersected estimate
Pcc {np.ndarray} -- intersected covariance
"""
Pa_inv = np.linalg.inv(Pa)
Pb_inv = np.linalg.inv(Pb)
fxn = lambda omega: np.trace(
np.linalg.inv(omega * Pa_inv + (1 - omega) * Pb_inv))
omega_optimal = scipy.optimize.minimize_scalar(fxn,
bounds=(0, 1),
method="bounded").x
# print("Omega: {}".format(omega_optimal)) # We'd expect a value of 1
Pcc = np.linalg.inv(omega_optimal * Pa_inv +
(1 - omega_optimal) * Pb_inv)
c_bar = Pcc.dot(omega_optimal * Pa_inv.dot(xa) +
(1 - omega_optimal) * Pb_inv.dot(xb))
jump = max([np.linalg.norm(c_bar - xa), np.linalg.norm(c_bar - xb)])
if jump > 10: # Think this is due to a floating point error in the inversion
print("!!!!!!!!!!! BIG JUMP!!!!!!!")
print(xa)
print(xb)
print(c_bar)
print(omega_optimal)
print(Pa)
print(Pb)
print(Pcc)
return c_bar.reshape(-1, 1), Pcc
def psci(self, x_prior, P_prior, c_bar, Pcc):
""" Partial State Update all other states of the filter using the result of CI
Arguments:
x_prior {np.ndarray} -- This filter's prior estimate (over common states)
P_prior {np.ndarray} -- This filter's prior covariance
c_bar {np.ndarray} -- intersected estimate
Pcc {np.ndarray} -- intersected covariance
Returns:
None
Updates self.main_filter.filter.x_hat and P, the delta tier's primary estimate
"""
# Full state estimates
x = self.filter.x_hat
P = self.filter.P
D_inv = np.linalg.inv(Pcc) - np.linalg.inv(P_prior)
D_inv_d = np.dot(np.linalg.inv(Pcc), c_bar) - np.dot(
np.linalg.inv(P_prior), x_prior)
my_id = self.asset2id[self.my_name]
begin_ind = my_id * self.num_ownship_states
end_ind = (my_id + 1) * self.num_ownship_states
info_vector = np.zeros(x.shape)
info_vector[begin_ind:end_ind] = D_inv_d
info_matrix = np.zeros(P.shape)
info_matrix[begin_ind:end_ind, begin_ind:end_ind] = D_inv
posterior_cov = np.linalg.inv(np.linalg.inv(P) + info_matrix)
tmp = np.dot(np.linalg.inv(P), x) + info_vector
posterior_state = np.dot(posterior_cov, tmp)
self.filter.x_hat = posterior_state
self.filter.P = posterior_cov
def intersect(self, x, P):
"""Runs covariance intersection with main filter's estimate
Arguments:
x {np.ndarray} -- other filter's mean
P {np.ndarray} -- other filter's covariance
Returns:
c_bar {np.ndarray} -- intersected estimate
Pcc {np.ndarray} -- intersected covariance
"""
my_id = self.asset2id[self.my_name]
# Slice out overlapping states in main filter
begin_ind = my_id * self.num_ownship_states
end_ind = (my_id + 1) * self.num_ownship_states
x_prior = self.filter.x_hat[begin_ind:end_ind].reshape(-1, 1)
P_prior = self.filter.P[begin_ind:end_ind, begin_ind:end_ind]
P_prior = P_prior.reshape(self.num_ownship_states,
self.num_ownship_states)
c_bar, Pcc = LedgerFilter.run_covariance_intersection(
x, P, x_prior, P_prior)
# Update main filter states
if Pcc.shape != self.filter.P.shape:
self.psci(x_prior, P_prior, c_bar, Pcc)
# self.filter.x_hat[begin_ind:end_ind] = c_bar
# self.filter.P[begin_ind:end_ind,begin_ind:end_ind] = Pcc
else:
self.filter.x_hat = c_bar
self.filter.P = Pcc
return c_bar, Pcc
def reset_estimate(self):
self.filter.x_hat = self.ledger[len(self.ledger)]["x_hat_prior"]
self.filter.P = self.ledger[len(self.ledger)]["P_prior"]
def update(self, update_time, u, Q, nav_mean, nav_cov):
"""Execute Prediction & Correction Step in filter
Arguments:
update_time {time} -- Update time to record on the ledger update times
u {np.ndarray} -- control input (num_ownship_states / 2, 1)
Q {np.ndarray} -- motion/process noise (nstates, nstates)
nav filter mean
nav filter covariance
"""
# self.ledger[len(self.ledger)]["x_hat_prior"] =
# self.ledger[len(self.ledger)]["P_prior"] = deepcopy(self.filter.P)
self.meas_types_received = []
# Run prediction step
if len(self.ledger) > 1:
time_delta = (update_time -
self.ledger[len(self.ledger) - 1]["time"]).to_sec()
self.filter.predict(u, Q, time_delta, use_control_input=False)
# Add all measurements
# if self.my_name != "surface":
# print("### {} ###".format(self.my_name))
for ros_meas in self.ledger[len(self.ledger)]["meas"]:
src_id = self.asset2id[ros_meas.src_asset]
measured_id = self.asset2id[ros_meas.measured_asset]
meas = get_internal_meas_from_ros_meas(ros_meas, src_id,
measured_id)
# if self.my_name != "surface":
# print(self._get_meas_identifier(ros_meas))
self.filter.add_meas(meas)
# Run correction step on filter
self.filter.correct()
# Intersect
c_bar, Pcc = None, None
if self.is_main_filter and (nav_mean is not None
and nav_cov is not None):
# print("***************************8 Intersecting **********************************")
c_bar, Pcc = self.intersect(nav_mean, nav_cov)
# Save all variables of this update
self.ledger[len(self.ledger)]["time"] = update_time
self.ledger[len(self.ledger)]["u"] = u
self.ledger[len(self.ledger)]["Q"] = Q
self.ledger[len(self.ledger)]["nav_mean"] = nav_mean
self.ledger[len(self.ledger)]["nav_cov"] = nav_cov
self._add_block()
return c_bar, Pcc
def convert(self, delta_multiplier):
"""Converts the filter to have a new delta multiplier
Arguments:
delta_multiplier {float} -- the delta multiplier of the new filter
"""
self.delta_multiplier = delta_multiplier
def _get_meas_identifier(self, msg, undo=False):
""" Returns a unique string for that msg
sonar_x (implicit/explicit) me to agent0 --> sonar_x_me_agent0
if undo, msg is a "msg_id"/previous call to this function
"""
if not undo:
meas_type = msg.meas_type
if "implicit" in meas_type:
meas_type = meas_type.split("_implicit")[0]
elif "burst" in meas_type:
meas_type = meas_type.split("_burst")[0]
identifier = "{}-{}-{}".format(meas_type, msg.src_asset,
msg.measured_asset)
return identifier
else: # Go from msg (msg_id) ==> ros msg
meas_type, src_asset, measured_asset = msg.split("-")
m = Measurement()
m.meas_type = meas_type
m.src_asset = src_asset
m.measured_asset = measured_asset
return m
def _get_shareable_meas_dict(self, last_shared_index):
"""
Returns a measurement dict
msg_id ==> list of times the msg appears
==> list of explicit measurements
"""
meas_dict = {}
explicit_count = 0
for i in range(last_shared_index, len(self.ledger)):
for meas in self.ledger[i]["meas"]:
if self._is_shareable(meas.src_asset, meas.meas_type):
msg_id = self._get_meas_identifier(meas)
if msg_id not in meas_dict:
meas_dict[msg_id] = {"times": [], "explicit": []}
meas_dict[msg_id]["times"].append(meas.stamp)
if "implicit" not in meas.meas_type:
meas_dict[msg_id]["explicit"].append(meas)
explicit_count += 1
# print("Delta: {} | Explicit Count creating meas dict: {}".format(self.delta_multiplier, explicit_count))
return meas_dict
def _get_meas_dict_from_buffer(self, buffer):
"""
Returns a measurement dictionary to assist with recreating the measurement sequence
msg_id ==> list of burst msgs
==> list of epxlicit measurements
"""
meas_dict = {}
for meas in buffer:
msg_id = self._get_meas_identifier(meas)
if msg_id not in meas_dict:
meas_dict[msg_id] = {"bursts": [], "explicit": []}
if "burst" in meas.meas_type:
meas_dict[msg_id]["bursts"].append(meas)
else:
meas_dict[msg_id]["explicit"].append(meas)
return meas_dict
def _get_bursts(self, times, threshold=3):
last_time = None
bursts = [[]]
for t in times:
if last_time is None or (t - last_time).to_sec() < threshold:
bursts[-1].append(t)
else:
bursts.append([t])
last_time = t
return bursts
def _make_burst_msg(self, msg_id, value, start_time, avg_latency_s):
meas = self._get_meas_identifier(msg_id, undo=True)
meas.meas_type += "_burst"
assert avg_latency_s < 10 # Needed for way we are sending
meas.data = value + (avg_latency_s / 10.0)
meas.stamp = start_time
return meas
def _expand_burst_msg(self, burst_msg):
"""
Turn a burst msg into many implicit measurements
"""
assert "burst" in burst_msg.meas_type
burst_list = []
num_msgs = int(burst_msg.data)
avg_latency = (burst_msg.data - int(burst_msg.data)) * 10
# burst_msg.meas_type = burst_msg.meas_type.split("_burst")[0]
msg_id = self._get_meas_identifier(burst_msg)
# print("Reconstructed msg_id: {}".format(msg_id))
# print("Avg latency: {}".format(avg_latency))
# print("Num msgs: {}".format(num_msgs))
for i in range(num_msgs):
new_msg = self._get_meas_identifier(msg_id, undo=True)
new_msg.stamp = burst_msg.stamp + rospy.Duration(i * avg_latency)
new_msg.meas_type += "_implicit"
new_msg.variance = burst_msg.variance
new_msg.et_delta = burst_msg.et_delta
burst_list.append(new_msg)
return burst_list, avg_latency
def _add_variances(self, buffer):
for msg in buffer:
if "_burst" in msg.meas_type:
meas_type = msg.meas_type.split("_burst")[0]
else:
meas_type = msg.meas_type
msg.variance = self.default_meas_variance[meas_type] * 2.0
return buffer
def _add_etdeltas(self, buffer, delta_multiplier):
for msg in buffer:
if "_burst" in msg.meas_type:
meas_type = msg.meas_type.split("_burst")[0]
msg.et_delta = self.delta_codebook_table[
meas_type] * delta_multiplier
else:
msg.et_delta = self.delta_codebook_table[
msg.meas_type] * delta_multiplier
# print(buffer)
return buffer
def pull_buffer(self, last_shared_index):
"""Returns the event triggered buffer
Returns:
list -- the flushed buffer of measurements
"""
buffer = []
explicit_buffer = []
# report_implicit_count = 0
# report_last_shared_time = self.ledger[last_shared_index]["time"]
# report_now_last_shared_time = rospy.get_rostime()
# report_duration = report_now_last_shared_time - report_last_shared_time
meas_dict = self._get_shareable_meas_dict(last_shared_index)
print("PULLING BUFFER: current index {}".format(len(self.ledger)))
for msg_id in meas_dict:
times = meas_dict[msg_id]["times"] # Should be sorted
explicit = meas_dict[msg_id]["explicit"]
bursts = self._get_bursts(times)
# print("Delta: {} | Msg id: {} | Num Explicit: {}".format(self.delta_multiplier, msg_id, len(explicit)))
# print("size(times): {}".format(len(times)))
# print("size(explicit): {}".format(len(explicit)))
# print("bursts: {}".format(bursts))
if len(bursts) > 1:
print("ERROR MULTIPLE BURSTS DETECTED")
print(bursts)
b = bursts[-1] # Only use last burst
b_numpy = np.array(b)
start_time = b[0]
# print("Constructing msg: {}".format(msg_id))
if len(b) > 1:
cumdiff = b_numpy[
1:] - b_numpy[:-1] # Get the adjacent difference
latencies = [lat.to_sec() for lat in cumdiff]
mean_lat = np.mean(latencies)
# print("Avg latency: {}".format(mean_lat))
else:
mean_lat = 0
# print("Num msgs: {}".format(len(b)))
burst_msg = self._make_burst_msg(msg_id, len(b), start_time,
mean_lat)
buffer.append(burst_msg)
explicit_buffer.extend(explicit)
# report_implicit_count += (len(b) - len(explicit))
meas_sort = lambda x: x.stamp
explicit_buffer.sort(key=meas_sort, reverse=True)
buffer.extend(explicit_buffer)
# REPORT
# print("******* BUFFER SHARING REPORT FOR {} w/ Delta {}*******".format(self.my_name, self.delta_multiplier))
# print("Last shared time: {}".format(report_last_shared_time.to_sec()))
# print("Sharing duration: {}".format(report_duration.to_sec()))
# print("Sharing time now: {}".format(report_now_last_shared_time.to_sec()))
# print("Implicit cnt: {}".format(report_implicit_count))
# print("Explicit cnt: {}".format(len(explicit_buffer)))
return buffer # Delta-Tiering
# return explicit_buffer # N-most recent
def fillin_buffer(self, buffer, delta_multiplier):
# Add variances & et-deltas
buffer = self._add_variances(buffer)
buffer = self._add_etdeltas(buffer, delta_multiplier)
# Delta-tiering
new_buffer = []
implicit_cnt, explicit_cnt = 0, 0
# N-most recent
# new_buffer = buffer
# implicit_cnt, explicit_cnt = 0, len(buffer)
meas_dict = self._get_meas_dict_from_buffer(buffer)
for msg_id in meas_dict:
bursts = meas_dict[msg_id]["bursts"]
explicit = meas_dict[msg_id]["explicit"]
meas_sort = lambda x: x.stamp
explicit.sort(key=meas_sort)
# print("Explicit meas:")
# print(explicit)
all_implicit = []
for b in bursts:
implicit_meas, avg_latency = self._expand_burst_msg(b)
all_implicit.extend(implicit_meas)
all_implicit.sort(key=meas_sort)
# Match all of the explicit to their corresponding implicit placeholders:
# This works by first aligning the explicit with the last measurements in the implicit array
# Then move the first explicit forward in the implicit array to the best match
# Then proceed with each explicit sequentially, moving it forward and matching to the remaining best fits
# assert len(all_implicit) >= len(explicit) # Uneeded with following code
left_over_explicit = []
if len(all_implicit) < len(explicit): # We dropped a burst msg
first_implicit, final_implicit = all_implicit[0], all_implicit[
-1]
for m in explicit:
if m.stamp < first_implicit.stamp or m.stamp > final_implicit.stamp:
left_over_explicit.append(m)
for m in left_over_explicit:
explicit.remove(m)
size_diff = len(all_implicit) - len(explicit)
indices = [x + size_diff for x in range(len(explicit))]
for i in range(len(explicit)):
start_ind = 0 if i == 0 else indices[i - 1]
end_ind = indices[i]
if start_ind == end_ind:
break
search_times = [
x.stamp for x in all_implicit[start_ind:end_ind]
]
diffs = [
abs((x - explicit[i].stamp).to_sec()) for x in search_times
]
best_ind = np.argmin(diffs) + start_ind
indices[i] = best_ind
# print("Indices: {}".format(indices))
for i in range(len(indices)):
all_implicit[indices[i]] = explicit[i]
implicit_cnt += (len(all_implicit) - len(indices))
explicit_cnt += len(indices) + len(left_over_explicit)
# print(all_implicit)
new_buffer.extend(all_implicit)
new_buffer.extend(left_over_explicit)
return new_buffer
def catch_up(self, start_ind):
"""
Rewinds the filter and brings it up to the current momment in time
"""
if self.is_main_filter:
print("################## Starting Index: {} ################".
format(start_ind))
self.explicit_count = 0
ledger = deepcopy(self.ledger)
# print("DT: {}".format(self.delta_multiplier))
# print(ledger[start_ind]["P_prior"])
if ledger[start_ind]["x_hat_prior"] is None or ledger[start_ind][
"P_prior"] is None:
start_ind -= 1
# print("Start index: {}".format(start_ind))
# Reset the ledger
self.ledger = {}
for i in range(1, start_ind):
self.ledger[i] = ledger[i]
self._add_block()
# Reset the filter
# self.filter = deepcopy(self.original_filter)
self.filter.x_hat = ledger[start_ind]["x_hat_prior"]
self.filter.P = ledger[start_ind]["P_prior"]
for i_step in range(start_ind, len(ledger)):
meas_list = ledger[i_step]["meas"]
update_time = ledger[i_step]["time"]
u = ledger[i_step]["u"]
Q = ledger[i_step]["Q"]
nav_mean = ledger[i_step]["nav_mean"]
nav_cov = ledger[i_step]["nav_cov"]
for meas in meas_list:
self.add_meas(meas)
self.update(update_time, u, Q, nav_mean, nav_cov)
def get_asset_estimate(self, asset):
asset_id = self.asset2id[asset]
begin_ind = asset_id * self.num_ownship_states
end_ind = (asset_id + 1) * self.num_ownship_states
asset_mean = self.filter.x_hat[begin_ind:end_ind, 0]
asset_unc = self.filter.P[begin_ind:end_ind, begin_ind:end_ind]
return deepcopy(asset_mean), deepcopy(asset_unc)
def _get_meas_et_delta(self, meas_type):
"""Gets the delta trigger for the measurement
Arguments:
meas_type {str} -- The measurement type
Raises:
KeyError: ros_meas.meas_type not found in the delta_codebook_table
Returns:
float -- the delta trigger scaled by the filter's delta multiplier
"""
# Match root measurement type e.g. "modem_range" with "modem_range_implicit"
for mt in self.delta_codebook_table:
if mt in meas_type:
return self.delta_codebook_table[mt] * self.delta_multiplier
raise KeyError("Measurement Type " + meas_type +
" not found in self.delta_codebook_table")
class LedgerFilter:
"""Records filter inputs and makes available an event triggered buffer. """
def __init__(self, num_ownship_states, x0, P0, buffer_capacity, meas_space_table, missed_meas_tolerance_table, delta_codebook_table, delta_multiplier, is_main_filter, my_id):
"""Constructor
Arguments:
num_ownship_states {int} -- Number of ownship states for each asset
x0 {np.ndarray} -- initial states
P0 {np.ndarray} -- initial uncertainty
buffer_capacity {int} -- capacity of measurement buffer
meas_space_table {dict} -- Hash that stores how much buffer space a measurement takes up. Str (meas type) -> int (buffer space)
Must have key entries "bookend", "bookstart" to indicate space needed for measurement implicitness filling in
missed_meas_tolerance_table {dict} -- Hash that determines how many measurements of each type do we need to miss before indicating a bookend
delta_codebook_table {dict} -- Hash thatp stores delta trigger for each measurement type. Str(meas type) -> float (delta trigger)
delta_multiplier {float} -- Delta trigger constant multiplier for this filter
is_main_filter {bool} -- Is this filter a common or main filter (if main the meas buffer does not matter)
my_id {int} -- ID# of the current asset (typically 0)
"""
if delta_multiplier <= 0:
raise ValueError("Delta Multiplier must be greater than 0")
self.original_estimate = [deepcopy(x0), deepcopy(P0)]
self.delta_codebook_table = delta_codebook_table
self.delta_multiplier = delta_multiplier
self.buffer = MeasurementBuffer(meas_space_table, buffer_capacity)
self.missed_meas_tolerance_table = missed_meas_tolerance_table
self.is_main_filter = is_main_filter
self.filter = ETFilter(my_id, num_ownship_states, 3, x0, P0, True)
self.my_id = my_id
# Initialize Ledgers
self.ledger_meas = [] # In internal measurement form
self.ledger_control = [] ## elements with [u, Q, time_delta, use_control_input]
self.ledger_ci = [] ## Covariance Intersection ledger, each element is of form [x, P]
self.ledger_update_times = [] ## Update times of when correction step executed
self.expected_measurements = {} # When we don't receive an expected measurement we need to insert a "bookend" into the measurement buffer
# Initialize first element of ledgers
self.ledger_meas.append([])
self.ledger_control.append([])
self.ledger_ci.append([])
def add_meas(self, ros_meas, src_id, measured_id, delta_multiplier=THIS_FILTERS_DELTA, force_fuse=True):
"""Adds and records a measurement to the filter
Measurements after last correction step time will be fused at next correction step
measurements before will be recorded and fused in catch_up()
Arguments:
ros_meas {etddf.Measurement.msg} -- The measurement in ROS form
src_id {int} -- asset ID that took the measurement
measured_id {int} -- asset ID that was measured (can be any value for ownship measurement)
Keyword Arguments:
delta_multiplier {float} -- Delta multiplier to use for this measurement (default: {THIS_FILTERS_DELTA})
force_fuse {bool} -- If measurement is in the past, fuse it on the next update step anyway (default: {True})
Note: the ledger will still reflect the correct measurement time
"""
# Get the delta trigger for this measurement
et_delta = self._get_meas_et_delta(ros_meas)
# Check if we're not using a standard delta_multiplier
if delta_multiplier != THIS_FILTERS_DELTA:
et_delta = (et_delta / self.delta_multiplier) * delta_multiplier # Undo delta multiplication and scale et_delta by new multiplier
# Get the update time index of the measurement
time_index = self._get_time_index(ros_meas.stamp)
# Convert ros_meas to an implicit or explicit internal measurement
meas = self._get_internal_meas_from_ros_meas(ros_meas, src_id, measured_id, et_delta)
orig_meas = meas
# Common filter with delta tiering
if (not self.is_main_filter and time_index==FUSE_MEAS_NEXT_UPDATE) and src_id == self.my_id:
# Check if this measurement is allowed to be sent implicitly
l = [x for x in MEASUREMENT_TYPES_NOT_SHARED if x in ros_meas.meas_type]
if not l:
# Check for Implicit Update
if self.filter.check_implicit(meas):
# Check if this is the first of the measurement stream, if so, insert a bookstart
bookstart = meas.__class__.__name__ not in self.expected_measurements.keys()
if bookstart:
self.buffer.insert_marker(ros_meas, ros_meas.stamp, bookstart=True)
meas = Asset.get_implicit_msg_equivalent(meas)
# Fuse explicitly
else:
# TODO Check for overflow
self.buffer.add_meas(deepcopy(ros_meas))
# Indicate we receieved our expected measurement
missed_tolerance = deepcopy(self.missed_meas_tolerance_table[ros_meas.meas_type])
self.expected_measurements[orig_meas.__class__.__name__] = [missed_tolerance, ros_meas]
# Append to the ledger
self.ledger_meas[time_index].append(meas)
# Fuse on next timestamp
if time_index == FUSE_MEAS_NEXT_UPDATE or force_fuse:
self.filter.add_meas(meas)
else:
pass # Measurement will be fused on delta_tier's catch_up()
def predict(self, u, Q, time_delta=1.0, use_control_input=False):
"""Executes filter's prediction step
Arguments:
u {np.ndarray} -- control input (num_ownship_states / 2, 1)
Q {np.ndarray} -- motion/process noise (nstates, nstates)
Keyword Arguments:
time_delta {float} -- Amount of time to predict in future (default: {1.0})
use_control_input {bool} -- Whether to use control input or assume constant velocity (default: {False})
"""
self.filter.predict(u, Q, time_delta, use_control_input)
self.ledger_control[-1] = [u, Q, time_delta, use_control_input]
def correct(self, update_time):
"""Execute Correction Step in filter
Arguments:
update_time {time} -- Update time to record on the ledger update times
"""
# Check if we received all of the measurements we were expecting
for emeas in self.expected_measurements.keys():
[rx, ros_meas] = self.expected_measurements[emeas]
# We have reached our tolerance on the number of updates without receiving this measurement
if rx < 1:
self.buffer.insert_marker(ros_meas, update_time, bookstart=False)
del self.expected_measurements[emeas]
else:
self.expected_measurements[emeas] = [rx - 1, ros_meas]
# Run correction step on filter
self.filter.correct()
self.ledger_update_times.append(update_time)
# Initialize next element of ledgers
self.ledger_meas.append([])
self.ledger_control.append([])
self.ledger_ci.append([])
def convert(self, delta_multiplier):
"""Converts the filter to have a new delta multiplier
Arguments:
delta_multiplier {float} -- the delta multiplier of the new filter
"""
self.delta_multiplier = delta_multiplier
def check_overflown(self):
"""Checks whether the filter's buffer has overflown
Returns:
bool -- True if buffer has overflown
"""
return self.buffer.check_overflown()
def peek(self):
""" Allows peeking of the buffer
Returns:
list -- the current state of the buffer
"""
return self.buffer.peek()
def flush_buffer(self, final_time):
"""Returns the event triggered buffer
Arguments:
final_time {time} -- the last time measurements were considered to be added to the buffer
Returns:
list -- the flushed buffer of measurements
"""
self.expected_measurements = {}
return self.buffer.flush(final_time)
def reset(self, buffer, ledger_update_times, ledger_meas, ledger_control=None, ledger_ci=None):
"""Resets a ledger filter with the inputted ledgers
Arguments:
buffer {MeasurementBuffer} -- Measurement buffer to be preserved
ledger_update_times {list} -- Update times
ledger_meas {list} -- List of measurements at each update time
Keyword Arguments:
ledger_control {list} -- List of control inputs (default: {None})
ledger_ci {list} -- List of covariance intersections (default: {None})
Raises:
ValueError: lengths of ledgers do not match
"""
self.buffer = deepcopy(buffer)
self.ledger_update_times = deepcopy(ledger_update_times)
# Measurement Ledger
self.ledger_meas = deepcopy(ledger_meas)
if len(self.ledger_meas)-1 != len(self.ledger_update_times):
raise ValueError("Meas Ledger does not match length of update times!")
# Control Input Ledger
if ledger_control is not None:
self.ledger_control = ledger_control
if len(self.ledger_control)-1 != len(self.ledger_update_times):
raise ValueError("Control Ledger does not match length of update times!")
else:
# Initialize with empty lists
self.ledger_control = [[] for _ in range(len(self.ledger_update_times))]
if not self.ledger_control:
self.ledger_control = [[]]
# Covariance intersection ledger
if ledger_ci is not None:
self.ledger_ci = ledger_ci
if len(self.ledger_ci)-1 != len(self.ledger_update_times):
raise ValueError("CI Ledger does not match length of update times!")
else:
# Initialize with empty lists
self.ledger_ci = [[] for _ in range(len(self.ledger_update_times))]
def _get_meas_et_delta(self, ros_meas):
"""Gets the delta trigger for the measurement
Arguments:
ros_meas {etddf.Measurement.msg} -- The measurement in ROS form
Raises:
KeyError: ros_meas.meas_type not found in the delta_codebook_table
Returns:
float -- the delta trigger scaled by the filter's delta multiplier
"""
# Match root measurement type e.g. "modem_range" with "modem_range_implicit"
for meas_type in self.delta_codebook_table.keys():
if meas_type in ros_meas.meas_type:
return self.delta_codebook_table[meas_type] * self.delta_multiplier
raise KeyError("Measurement Type " + ros_meas.meas_type + " not found in self.delta_codebook_table")
def _get_internal_meas_from_ros_meas(self, ros_meas, src_id, measured_id, et_delta):
"""Converts etddf/Measurement.msg (implicit or explicit) to a class in etddf/measurements.py
Arguments:
ros_meas {etddf.Measurement.msg} -- The measurement in ROS form
src_id {int} -- asset ID that took the measurement
measured_id {int} -- asset ID that was measured (can be any value for ownship measurement)
et_delta {float} -- Delta trigger for this measurement
Raises:
NotImplementedError: Conversion between measurements forms has not been specified
Returns:
etddf.measurements.Explicit -- measurement in filter's internal form
"""
if "implicit" not in ros_meas.meas_type:
if ros_meas.meas_type == "depth":
return GPSz_Explicit(src_id, ros_meas.data, ros_meas.variance, et_delta)
elif ros_meas.meas_type == "modem_range" and not ros_meas.global_pose: # check global_pose list empty
return Range_Explicit(src_id, measured_id, ros_meas.data, ros_meas.variance, et_delta)
elif ros_meas.meas_type == "modem_range":
return RangeFromGlobal_Explicit(measured_id, \
np.array(ros_meas.global_pose).reshape(-1,1),\
ros_meas.data, ros_meas.variance, et_delta)
elif ros_meas.meas_type == "modem_azimuth" and not ros_meas.global_pose: # check global_pose list empty
return Azimuth_Explicit(src_id, measured_id, ros_meas.data, ros_meas.variance, et_delta)
elif ros_meas.meas_type == "modem_azimuth":
return AzimuthFromGlobal_Explicit(measured_id, \
np.array(ros_meas.global_pose).reshape(-1,1),\
ros_meas.data, ros_meas.variance, et_delta)
elif ros_meas.meas_type == "dvl_x":
return Velocityx_Explicit(src_id, ros_meas.data, ros_meas.variance, et_delta)
elif ros_meas.meas_type == "dvl_y":
return Velocityy_Explicit(src_id, ros_meas.data, ros_meas.variance, et_delta)
# Sonar asset
elif ros_meas.meas_type == "sonar_x" and not ros_meas.global_pose:
return LinRelx_Explicit(src_id, measured_id, ros_meas.data, ros_meas.variance, et_delta)
elif ros_meas.meas_type == "sonar_y" and not ros_meas.global_pose:
return LinRely_Explicit(src_id, measured_id, ros_meas.data, ros_meas.variance, et_delta)
elif ros_meas.meas_type == "sonar_z":
return LinRelz_Explicit(src_id, measured_id, ros_meas.data, ros_meas.variance, et_delta)
# Sonar Landmark
elif ros_meas.meas_type == "sonar_x" and ros_meas.global_pose:
return GPSx_Explicit(src_id, ros_meas.global_pose[0] - ros_meas.data, ros_meas.variance, et_delta)
elif ros_meas.meas_type == "sonar_y" and ros_meas.global_pose:
return GPSy_Explicit(src_id, ros_meas.global_pose[1] - ros_meas.data, ros_meas.variance, et_delta)
elif ros_meas.meas_type == "gps_x":
return GPSx_Explicit(src_id, ros_meas.data, ros_meas.variance, et_delta)
elif ros_meas.meas_type == "gps_y":
return GPSy_Explicit(src_id, ros_meas.data, ros_meas.variance, et_delta)
else:
raise NotImplementedError(str(ros_meas))
# Implicit Measurement
else:
if ros_meas.meas_type == "depth_implicit":
return GPSz_Implicit(src_id, ros_meas.variance, et_delta)
elif ros_meas.meas_type == "dvl_x_implicit":
return Velocityx_Implicit(src_id, ros_meas.variance, et_delta)
elif ros_meas.meas_type == "dvl_y_implicit":
return Velocityy_Implicit(src_id, ros_meas.variance, et_delta)
elif ros_meas.meas_type == "sonar_x_implicit":
return LinRelx_Implicit(src_id, measured_id, ros_meas.variance, et_delta)
elif ros_meas.meas_type == "sonar_y_implicit":
return LinRely_Implicit(src_id, measured_id, ros_meas.variance, et_delta)
elif ros_meas.meas_type == "sonar_z_implicit":
return LinRelz_Implicit(src_id, measured_id, ros_meas.variance, et_delta)
else:
raise NotImplementedError(str(ros_meas))
def _get_time_index(self, time_):
"""Converts a time to an update time index
Uses the ledger of correction step times
Arguments:
time_ {time} -- Time to convert
Returns:
int -- corresponding index in the measurement,ci and control ledger
if time_ > last update time --> returns FUSE_MEAS_NEXT_UPDATE
"""
# Check if we're fusing at next measurement time
if len(self.ledger_update_times) == 0 or time_ > self.ledger_update_times[-1]:
return FUSE_MEAS_NEXT_UPDATE
# Lookup on what index this corresponds to in the ledger_update_times
# Note: len(ledger_meas/control/ci) is always 1 greater than len(ledger_update_times)
# Therefore, the first if statement in this fxn is for filling that last/newest slot
# This for loop then has a 1 to 1 correspondence: ledger_update_times[i] corresponds to ledger_meas/control/ci[i]
# The subtraction and addition below of indices is for zero order holding all measurements between times
# t1 and t2 to be associated with time t2
for ind in reversed(range(len(self.ledger_update_times) - 1)):
if time_ > self.ledger_update_times[ind]:
return ind + 1
return 0