Tracking error fixes (#549)

* Fixing direction depending on where pier is pointed.

Closes #495

pocs/images.py

@@ -129,10 +129,10 @@ def pointing_error(self):
             d_ra = self.pointing.ra - self.header_pointing.ra
 
             self._pointing_error = OffsetError(
-                d_ra.to(
-                    u.arcsec), d_dec.to(
-                    u.arcsec), mag.to(
-                    u.arcsec))
+                d_ra.to(u.arcsec),
+                d_dec.to(u.arcsec),
+                mag.to(u.arcsec)
+            )
 
         return self._pointing_error
 

pocs/mount/mount.py

@@ -72,8 +72,8 @@ def __init__(self, location, commands=None, *args, **kwargs
         self._state = 'Parked'
 
         self.sidereal_rate = ((360 * u.degree).to(u.arcsec) / (86164 * u.second))
-        self.ra_guide_rate = 0.5  # Sidereal
-        self.dec_guide_rate = 0.5  # Sidereal
+        self.ra_guide_rate = 0.9  # Sidereal
+        self.dec_guide_rate = 0.9  # Sidereal
         self._tracking_rate = 1.0  # Sidereal
         self._tracking = 'Sidereal'
         self._movement_speed = ''
@@ -311,6 +311,121 @@ def distance_from_target(self):
 
         return separation
 
+    def get_tracking_correction(self, offset_info, pointing_ha):
+        """Determine the needed tracking corrections from current position.
+
+        This method will determine the direction and number of milliseconds to
+        correct the mount for each axis in order to correct for any tracking
+        drift. The Declination axis correction ('north' or 'south') depends on
+        the movement of the camera box with respect to the pier, which can be
+        determined from the Hour Angle (HA) of the pointing image in the sequence.
+
+        Note:
+            Correction values below 50ms will be skipped and values above 99999ms
+            will be clipped.
+
+        Args:
+            offset_info (`OffsetError`): A named tuple describing the offset
+                error. See `pocs.images.OffsetError`.
+            pointing_ha (float): The Hour Angle (HA) of the mount at the
+                beginning of the observation sequence in degrees. This affects
+                the direction of the Dec adjustment.
+
+        Returns:
+            dict: Offset corrections for each axis as needed ::
+
+                dict: {
+                    # axis: (arcsec, millisecond, direction)
+                    'ra': (float, float, str),
+                    'dec': (float, float, str),
+                }
+        """
+        pier_side = 'east'
+        if pointing_ha <= 12:
+            pier_side = 'west'
+
+        self.logger.debug("Mount pier side: {}".format(pier_side))
+
+        axis_corrections = {
+            'dec': None,
+            'ra': None,
+        }
+
+        for axis in axis_corrections.keys():
+            # find the number of ms and direction for Dec axis
+            offset = getattr(offset_info, 'delta_{}'.format(axis))
+            offset_ms = self.get_ms_offset(offset, axis=axis)
+
+            if axis == 'dec':
+                # Determine which direction to move based on direction mount
+                # is moving (i.e. what side it started on).
+                if pier_side == 'east':
+                    if offset_ms >= 0:
+                        delta_direction = 'north'
+                    else:
+                        delta_direction = 'south'
+                else:
+                    if offset_ms >= 0:
+                        delta_direction = 'south'
+                    else:
+                        delta_direction = 'north'
+            else:
+                if offset_ms >= 0:
+                    delta_direction = 'west'
+                else:
+                    delta_direction = 'east'
+
+            offset_ms = abs(offset_ms.value)
+
+            # Skip short corrections
+            if offset_ms <= 50:
+                continue
+
+            # Ensure we don't try to move for too long
+            max_time = 99999
+
+            # Correct long offset
+            if offset_ms > max_time:
+                offset_ms = max_time
+
+            axis_corrections[axis] = (offset, offset_ms, delta_direction)
+
+        return axis_corrections
+
+    def correct_tracking(self, correction_info, axis_timeout=30.):
+        """ Make tracking adjustment corrections.
+
+        Args:
+            correction_info (dict[tuple]): Correction info to be applied, see
+                `get_tracking_correction`.
+            axis_timeout (float, optional): Timeout for adjustment in each axis,
+                default 30 seconds.
+
+        Raises:
+            `error.Timeout`: Timeout error.
+        """
+        for axis, corrections in correction_info.items():
+            offset = corrections[0]
+            offset_ms = corrections[1]
+            delta_direction = corrections[2]
+
+            self.logger.info("Adjusting {}: {} {:0.2f} ms {:0.2f}".format(
+                axis, delta_direction, offset_ms, offset))
+
+            self.mount.query(
+                'move_ms_{}'.format(delta_direction),
+                '{:05.0f}'.format(offset_ms)
+            )
+
+            # Adjust tracking for `axis_timeout` seconds then fail if not done.
+            start_tracking_time = current_time()
+            while self.mount.is_tracking is False:
+                if (current_time() - start_tracking_time).sec > axis_timeout:
+                    raise error.Timeout("Tracking adjustment timeout: {}".format(axis))
+
+                self.logger.debug("Waiting for {} tracking adjustment".format(axis))
+                time.sleep(0.5)
+
 
 ##################################################################################################
 # Movement methods

pocs/observatory.py

@@ -1,5 +1,4 @@
 import os
-import time
 
 from collections import OrderedDict
 from datetime import datetime
@@ -342,67 +341,24 @@ def update_tracking(self):
         if self.current_offset_info is not None:
             self.logger.debug("Updating the tracking")
 
-            # find the number of ms and direction for Dec axis
-            dec_offset = self.current_offset_info.delta_dec
-            dec_ms = self.mount.get_ms_offset(dec_offset, axis='dec')
-            if dec_offset >= 0:
-                dec_direction = 'north'
-            else:
-                dec_direction = 'south'
+            # Get the pier side of pointing image
+            pointing_ha = self.current_observation.pointing_image.header_ha
 
-            # find the number of ms and direction for RA axis
-            ra_offset = self.current_offset_info.delta_ra
-            ra_ms = self.mount.get_ms_offset(ra_offset, axis='ra')
-            if ra_offset >= 0:
-                ra_direction = 'west'
-            else:
-                ra_direction = 'east'
-
-            dec_ms = abs(dec_ms.value) * 1.5  # TODO(wtgee): Figure out why 1.5
-            ra_ms = abs(ra_ms.value) * 1.
-
-            # Ensure we don't try to move for too long
-            max_time = 99999
-
-            # Correct the Dec axis (if offset is large enough)
-            if dec_ms > max_time:
-                dec_ms = max_time
-
-            if dec_ms >= 50:
-                self.logger.info("Adjusting Dec: {} {:0.2f} ms {:0.2f}".format(
-                    dec_direction, dec_ms, dec_offset))
-                if dec_ms >= 1. and dec_ms <= max_time:
-                    self.mount.query('move_ms_{}'.format(
-                        dec_direction), '{:05.0f}'.format(dec_ms))
-
-                # Adjust tracking for up to 30 seconds then fail if not done.
-                start_tracking_time = current_time()
-                while self.mount.is_tracking is False:
-                    if (current_time() - start_tracking_time).sec > 30:
-                        raise Exception("Trying to adjust Dec tracking for more than 30 seconds")
-
-                    self.logger.debug("Waiting for Dec tracking adjustment")
-                    time.sleep(0.1)
-
-            # Correct the RA axis (if offset is large enough)
-            if ra_ms > max_time:
-                ra_ms = max_time
-
-            if ra_ms >= 50:
-                self.logger.info("Adjusting RA: {} {:0.2f} ms {:0.2f}".format(
-                    ra_direction, ra_ms, ra_offset))
-                if ra_ms >= 1. and ra_ms <= max_time:
-                    self.mount.query('move_ms_{}'.format(
-                        ra_direction), '{:05.0f}'.format(ra_ms))
-
-                # Adjust tracking for up to 30 seconds then fail if not done.
-                start_tracking_time = current_time()
-                while self.mount.is_tracking is False:
-                    if (current_time() - start_tracking_time).sec > 30:
-                        raise Exception("Trying to adjust RA tracking for more than 30 seconds")
-
-                    self.logger.debug("Waiting for RA tracking adjustment")
-                    time.sleep(0.1)
+            try:
+                pointing_ha = pointing_ha.value
+            except AttributeError:
+                pass
+
+            self.logger.debug("Pointing HA: {}".format(pointing_ha))
+            correction_info = self.mount.get_tracking_correction(
+                self.current_offset_info,
+                pointing_ha
+            )
+
+            try:
+                self.mount.correct_tracking(correction_info)
+            except error.Timeout:
+                self.logger.warning("Timeout while correcting tracking")
 
     def get_standard_headers(self, observation=None):
         """Get a set of standard headers

pocs/tests/bisque/test_mount.py

@@ -115,13 +115,6 @@ def test_update_location(mount, config):
     assert mount.location == location2
 
 
-# def test_target_coords_below_horizon(mount, target_down):
-#     mount.initialize()
-
-#     assert mount.set_target_coordinates(target_down) is False
-#     assert mount.get_target_coordinates() is None
-
-
 def test_target_coords(mount, target):
     mount.initialize(unpark=True)
 

pocs/tests/test_ioptron.py

@@ -1,8 +1,33 @@
+import os
 import pytest
 
 from astropy.coordinates import EarthLocation
+from astropy import units as u
 
+from pocs.images import OffsetError
 from pocs.mount.ioptron import Mount
+from pocs.utils.config import load_config
+
+
+@pytest.fixture
+def location():
+    config = load_config(ignore_local=True)
+    loc = config['location']
+    return EarthLocation(lon=loc['longitude'], lat=loc['latitude'], height=loc['elevation'])
+
+
+@pytest.fixture(scope="function")
+def mount(config, location):
+    try:
+        del os.environ['POCSTIME']
+    except KeyError:
+        pass
+
+    config['mount'] = {
+        'brand': 'bisque',
+        'template_dir': 'resources/bisque',
+    }
+    return Mount(location=location, config=config)
 
 
 @pytest.mark.with_mount
@@ -64,3 +89,41 @@ def test_unpark_park(self):
         assert self.mount.is_parked is False
         self.mount.home_and_park()
         assert self.mount.is_parked is True
+
+
+def test_get_tracking_correction(mount):
+
+    offsets = [
+        # HA, ΔRA, ΔDec, Magnitude
+        (2, -13.0881456, 1.4009, 12.154),
+        (2, -13.0881456, -1.4009, 12.154),
+        (2, 13.0881456, 1.4009, 12.154),
+        (14, -13.0881456, 1.4009, 12.154),
+        (14, 13.0881456, 1.4009, 12.154),
+    ]
+
+    corrections = [
+        (103.49, 'south', 966.84, 'east'),
+        (103.49, 'north', 966.84, 'east'),
+        (103.49, 'south', 966.84, 'west'),
+        (103.49, 'north', 966.84, 'east'),
+        (103.49, 'north', 966.84, 'west'),
+    ]
+
+    for offset, correction in zip(offsets, corrections):
+        pointing_ha = offset[0]
+        offset_info = OffsetError(
+            offset[1] * u.arcsec,
+            offset[2] * u.arcsec,
+            offset[3] * u.arcsec
+        )
+        correction_info = mount.get_tracking_correction(offset_info, pointing_ha)
+
+        dec_info = correction_info['dec']
+        ra_info = correction_info['ra']
+
+        assert dec_info[1] == pytest.approx(correction[0], rel=1e-2)
+        assert dec_info[2] == correction[1]
+
+        assert ra_info[1] == pytest.approx(correction[2], rel=1e-2)
+        assert ra_info[2] == correction[3]