85 lines
2.9 KiB
Python
85 lines
2.9 KiB
Python
from threading import Thread
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from tracking import algorithms
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import tracking.lidar_tracker_pb2 as tracker_pb
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import zmq
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class LidarCache():
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"""
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A class that retrieves scans from the lidar,
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runs grouping algorithms between scans and
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keeps a copy of the group data.
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"""
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def __init__(self, lidar, measurements=100):
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self.lidar = lidar
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self.measurements = measurements
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print('Info: ' + self.lidar.get_info())
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print('Health: ' + self.lidar.get_health())
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self.run = True
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self.tracking_group_number = -1
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self.currentGroups = None
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self._group_listeners = []
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def start_cache(self):
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self.thread = Thread(target=self.do_scanning)
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self.thread.start()
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def do_scanning(self):
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"""Performs scans whilst cache is running, and will pass calculated groups data to the sender.
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Parameters
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----------
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listener:
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Any object that includes the onGroupsChanged method.
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"""
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# Batch over scans, so we don't need to do our own batching to determine groups
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# TODO: Implement custom batching, as iter_scans can be unreliable
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for scan in self.lidar.iter_scans(min_len=self.measurements):
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print('Got %d measurments' % (len(scan)))
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if len(scan) < self.measurements:
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# Poor scan, likely since it was the first scan.
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continue
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if not self.run:
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break
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# Now process the groups.
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if self.currentGroups is not None:
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self.currentGroups = algorithms.assign_groups(
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self.currentGroups, algorithms.calc_groups(scan))
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else:
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self.currentGroups = algorithms.calc_groups(scan)
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self.fireGroupsChanged()
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def fireGroupsChanged(self):
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# Send the updated groups to 0MQ socket.
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# Rename this to be a generic listener method, rather than an explicit 'send' (even though it can be treated as such already)
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pointScan = tracker_pb.PointScan()
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for group in self.currentGroups:
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for point in group.get_points():
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pointScan.points.append(tracker_pb.Point(
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angle=point[1], distance=point[2], group_number=group.number))
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for listener in self._group_listeners:
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listener.onGroupsChanged(pointScan)
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def add_groups_changed_listener(self, listener):
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"""
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Add a listener for a change in scans. THis will provide a tuple with the new group
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scans, which can then be sent off to a network listener for display, or to update the
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vehicle with a new velocity.
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Parameters
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----------
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listener
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An object that implements the onGroupsChanged(message) method.
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"""
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self._group_listeners.append(listener)
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def stop_scanning(self):
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self.run = False
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