Simple FLIR Pan Tilt Head Python Module

mosaic_sample1.py

#!/usr/bin/env python

# notional mosaic activity, without image acquisition
# sleeps removed since pan/tilt are now blocking

import time

from ptu import PanTiltUnit


def main():
    ptu = PanTiltUnit('hostname', '4000')

    # (p1,t1)
    positions = (
        (0, 0),
        (500, 0),
        (1000, 0),
        (1500, 0),
        (1500, 500),
        (1000, 500),
        (500, 500),
        (0, 500),
    )

    for pos in positions:
        pan, tilt = pos
        ptu.pan = pan
        ptu.tilt = tilt

    ptu.close()


if __name__ == '__main__':
    main()

ptu.py

import sys
import telnetlib
import logging
import time
import re


class PanTiltUnit(object):
    """PanTiltUnit commands a FLIR PTU

    Example:

    >>> from ptu import PanTiltUnit
    >>> ptu = PanTiltUnit('hostname', '4000')
    >>> ptu.pan
    0
    >>> ptu.pan = 1000
    >>> ptu.pan
    1000
    >>> ptu.close()
    """

    POS_REGEX = re.compile(
        r"\* Current (?P<direction>(Pan|Tilt)) position is (?P<position>\d+)\r\n"
    )

    def __init__(self, host, port, no_connect=None):
        super(PanTiltUnit, self).__init__()
        self.host = host
        self.port = port
        self._connection = None

        if not no_connect:
            self._connect()

    def _connect(self):
        logging.info("Connecting to %s:%s" % (self.host, self.port))
        self._connection = telnetlib.Telnet(self.host, self.port)
        logging.debug(self._connection.read_until("*"))

    def close(self):
        self._connection.close()

    def _set_position(self, direction, position):
        if direction == 'pan':
            message = 'pp' + str(position) + "\r\n"
        elif direction == 'tilt':
            message = 'tp' + str(position) + "\r\n"
        else:
            raise ValueError("direction must be 'pan' or 'tilt'")

        logging.debug(message)
        self._connection.write(message)
        logging.debug(self._connection.read_until("*"))

        # block while PTU still in motion
        while self._get_position(direction) != position:
            time.sleep(0.1)

    def _get_position(self, direction):
        """Returns current position for direction ('pan' or 'tilt')

        Keep in mind that pan position can be changing and this will return the
        instantaneous position which may differ from the target position.
        """
        if direction == 'pan':
            self._connection.write("pp\r\n")
            # read the pp\r\n line to junk variable, just to get rid of it
            _ = self._connection.read_until("pp\r\n")
            expected_direction = 'Pan'
        elif direction == 'tilt':
            self._connection.write("tp\r\n")
            # read the tp\r\n line to junk variable, just to get rid of it
            _ = self._connection.read_until("tp\r\n")
        else:
            raise ValueError("direction must be 'pan' or 'tilt'")

        # read in line with position information
        position_line = self._connection.read_until("\r\n")
        logging.debug(position_line)

        # extract out the postion information from the response received above
        match = re.match(PanTiltUnit.POS_REGEX, position_line)
        if match:
            # we cast the pan/tilt position value to integer so it is easier
            # do to math with the value
            return int(match.group('position'))
        else:
            logging.error("WARNING: Position not found for: %s" % direction)

    @property
    def pan(self):
        return self._get_position('pan')

    @pan.setter
    def pan(self, position):
        self._set_position('pan', position)

    @property
    def tilt(self):
        return self._get_position('tilt')

    @tilt.setter
    def tilt(self, position):
        self._set_position('tilt', position)


def main():
    pass


if __name__ == '__main__':
    main()