POSITION FIXING SYSTEMS AND METHODS
An electronic chart system (ECS) is configured to be coupled to a user interface. In one embodiment, the ECS is implemented using a logic device configured to obtain a predicted fix for a watercraft position. Based on the predicted fix, the logic device obtains an electronic chart of an area containing a location of the predicted fix. The logic device searches the electronic chart for static objects whose ranges and/or bearings are viewable from the watercraft at the predicted fix location. Other systems, methods, and devices are also provided.
1 . An apparatus comprising:
an electronic chart system (ECS) configured to be coupled to a user interface;
the ECS being implemented using a logic device configured to:
obtain a predicted fix for a watercraft position;
based on the predicted fix, obtain an electronic chart of an area containing a location of the predicted fix; and
search the electronic chart for static objects whose ranges and/or bearings are viewable from the watercraft at the predicted fix location.
2 . The apparatus of claim 1 , wherein the logic device is further configured to provide results of the search on the user interface.
3 . The apparatus of claim 2 , wherein providing the results comprises indicating on the user interface whether or not a three-point position fix is available based on static objects found in the search.
4 . The apparatus of claim 3 , wherein the logic device is further configured to:
control one or more ranging devices provided on the watercraft to take range measurements to at least two of the static objects, and obtain ranges based on the range measurements; and
calculate a watercraft position fix based on the obtained ranges.
5 . The apparatus of claim 4 , wherein the logic device is further configured to:
compare the calculated watercraft position fix with the predicted fix, and provide an alert on the user interface if the calculated watercraft position fix is outside a threshold compared to the predicted fix.
6 . The apparatus of claim 1 , wherein the logic device is further configured to:
control one or more ranging devices provided on the watercraft to take a range measurement to at least one of the static objects, and obtain a range based on the range measurement;
control a camera provided on the watercraft to capture an image of the at least one of the static objects; and
provide, on the user interface:
a range and a bearing that correspond to the range measurement; and
the captured image.
7 . The apparatus of claim 6 , wherein the one or more ranging devices comprise a laser range finder (LRF).
8 . The apparatus of claim 6 , wherein the one or more ranging devices comprise a radar and/or a sonar.
9 . The apparatus of claim 1 , wherein the logic device is configured to:
obtain, based on the electronic chart and the predicted fix, a predicted range and predicted bearing of at least one of static objects found in the search; and
control one or more ranging devices provided on the watercraft to take a range measurement based on the predicted bearing.
10 . The apparatus of claim 9 , wherein the logic device is further configured to:
if the range measurement is within a threshold compared to the predicted range, use the range measurement to calculate a fix for the watercraft; and
if the range measurement if outside of the threshold compared to the predicted range, then:
calculate a modified bearing based on the predicted bearing; and
control one or more ranging devices provided on the watercraft to take a range measurement based on the modified bearing.
11 . A method comprising performing, by a logic device used to implement an electronic chart system (ECS), operations of:
obtaining a predicted fix for a watercraft position;
based on the predicted fix, obtaining an electronic chart of an area containing a location of the predicted fix; and
searching the electronic chart for static objects whose ranges and/or bearings are viewable from the watercraft at the predicted fix location.
12 . The method of claim 11 , further comprising the logic device providing results of the search on a user interface coupled to the ECS.
13 . The method of claim 12 , wherein providing the results comprises indicating on the user interface whether or not a three-point position fix is available based on static objects found in the search.
14 . The method of claim 13 , further comprising the logic device performing operations of:
controlling one or more ranging devices provided on the watercraft to take range measurements to at least two of the static objects, and obtaining ranges based on the range measurements; and
calculating a watercraft position fix based on the obtained ranges.
15 . The method of claim 14 , further comprising the logic device performing operations of:
comparing the calculated watercraft position fix with the predicted fix, and providing an alert on the user interface if the calculated watercraft position fix is outside a threshold compared to the predicted fix.
16 . The method of claim 11 , further comprising the logic device performing operations of:
controlling one or more ranging devices provided on the watercraft to take a range measurement to at least one of the static objects, and obtaining a range based on the range measurement;
controlling a camera provided on the watercraft to capture an image of the at least one of the static objects; and
providing, on the user interface:
a range and a bearing that correspond to the range measurement; and
the captured image.
17 . The method of claim 16 , wherein the one or more ranging devices comprise a laser range finder (LRF).
18 . The method of claim 16 , wherein the one or more ranging devices comprise a radar and/or a sonar.
19 . The method of claim 11 , further comprising the logic device performing operations of:
obtaining, based on the electronic chart and the predicted fix, a predicted range and predicted bearing of at least one of static objects found in the search; and
controlling one or more ranging devices provided on the watercraft to take a range measurement based on the predicted bearing.
20 . The method of claim 19 , further comprising the logic device performing operations of:
if the range measurement is within a threshold compared to the predicted range, using the range measurement to calculate a fix for the watercraft; and
if the range measurement if outside of the threshold compared to the predicted range, then:
calculating a modified bearing based on the predicted bearing; and
controlling one or more ranging devices provided on the watercraft to take a range measurement based on the modified bearing.