Field of the Invention

This invention is directed generally to the field of guidance devices, and more particularly to an electronic guidance device, which provides a traveler with information as to the direction and distance from the traveler's present position to a desired location.

Background of the Invention

Present guidance systems employ complex indication man- machine interfaces. These guidance systems, in the form of radio navigation devices, such as NAVSTAR GPS (Global Positioning System) receivers, Loran C receivers, and the like, can provide a traveler with the latitude and longitude of the traveler's present position. If the latitude and longitude of a desired destination is input to the navigation device, the device can readily ascertain the distance and bearing to the destination from the user's present position. This is useful for skilled navigators in a controllable situation in which they may be provided detailed topological maps and a compass to guide them.

A problem with this approach arises when the traveler is not familiar with such traditional navigation practice, or when an experienced navigator gets into an uncontrollable situation. What travelers are most concerned about is getting lost. When a hunter for instance, is chasing a turkey, he has a need to run in a random pattern traversing potentially great distances while virtually focused on this turkey, until he completes his task. This may take minutes or hours. In another case, a casual traveler hikes for hours and gets in trouble when night falls as he can't navigate by sight anymore. Or an inexperienced traveler gets unexpectedly

separated from the group and is unable to find her way to a common meeting point. This can be fatal in some cases.

The basic compass also has its limitations as it requires someone with navigational ability to use it. Of course it only provides direction information not information about the traveler's current position, distance to destination or home position.

Summary of the Invention

The present invention encompasses a guidance device having an axis. This guidance device can determine a direction, and indicate with a discrete transition indicator when the guidance device axis is aligned with that direction.

Brief Description of the Drawings

FIG. 1 shows a guidance device constructed according to the invention; and

FIG. 2 is a sche atic block diagram illustrating the internal construction of the guidance device shown in FIG. 1.

Detailed Description of a Preferred Embodiment

The guidance device described herein offers an elegantly simple solution to the former problem statement This guidance device employs a simple indicator to communicate to the traveler pertinent information, such as direction to home (also referred to as trip origin or point of origin), direction to geographic north, and direction to. destination (also referred to as trip destination, location, or waypoint) when the traveler points the guidance

device in the correct direction. In addition, a configurable display is provided in order to communicate further information about the location of interest. This information may be in the form of latitude, longitude, altitude, estimated time of arrival, estimated time of transit and distance to the location to name a few. For instance the estimated time of arrival is based on time of day, distance traveled in last contiguous periods (indicating fatigue), altitude, and distance to the destination. The casual traveler, for instance, can enter his home position at the start of a trip. Later when he decides to return to home he simply points the guidance device and rotates in a circular pattern until the indicator transitions, indicating his direction home.

The preferred embodiment of the present invention is illustrated in FIG. 1. The guidance device 101 is powered on by the on/off switch 103. To identify the traveler's current position, the traveler initiates the mark/pos switch 105. Pos, in this case, is an abbreviation for position determination. The configurable display 115 will then display the traveler's current position. Of course being configurable allows the device to display other information such as altitude, time of day to indicate a few possibilities.

He may then choose to give a name to his current position. At this point, the cursor on the configurable display 115 is in the left uppermost position. The character displayed is an "A". By initiating the increment/decrement switch 109, the traveler then increments or decrements through the alphabet and the digits zero through nine, until he is satisfied with the first character naming the location defined in the former step, in this case home, or base camp or whatever he desires. The traveler then initiates the tab/backtab key 111 and the cursor moves to the next right most position on the configurable display 115. The traveler then repeats this sequence until he is satisfied with the second character defining the destination of interest. This process of incrementing and decrementing and tabbing/back tabbing is repeated until the traveler has entered the name of his current position. When this

process is complete, the traveler can store this current position name and location by initiating the mark/pos key 105. This action registers the current position into the waypoint database 219, that is part of the guidance computer 207 more fully disclosed later. Other definitions of position such as altitude, time and others are storable as well. Other naming schemes could include provision for selecting commonly used names from a menu.

The traveler then may enter a ^" destination by initiating first the increment/ decrement switch 109, which will change the latitude first. When the desired latitude is indicated on the configurable display 115, the traveler initiates the tab /backtab switch 111 to shift the configurable display 115 to longitude and then initiates the increment/decrement switch 109 to set the desired longitude. When both the latitude and longitude displayed on the configurable display 115, to the traveler's satisfaction, the traveler then initiates the erase/ wpt switch 113. This action stores the desired destination into the waypoint database 219. Of course the traveler could enter multiple destinations or waypoints in this manner with their respective names as described earlier.

The traveler can then start applying the guidance device to locate his destination, geographic north and home. He would typically do this by standing and holding the guidance device 101 pointed outwards. As the traveler rotates in a circular pattern, the guidance device 101 performs its indication and display function when the guidance device's axis, indicated in this case by the graphical arrow, encompassing the direction display, 119 is aligned with one of the predetermined directions, destination, geographic north or home. Of course the guidance device could also be mounted in a vehicle, such as a car or boat where as the bearing changed, the guidance device would indicate the direction of interest.

When the traveler points in the direction of geographic north, the discrete transition indication device 108, or simply an

SUBSTITUTE SHEET

indication device, in this case an LED, will change state from off to on. As the traveler continues to rotate, the indication device 108 will transition from on to off. As a traveler points to a predetermined destination, the indication device 106 will change from off to on. As the traveler continues to rotate the indication device 106 will transition from on to off. As a traveler points to a predetermined trip origin, or home position, the indication device 104 will change from off to on. As the traveler continues to rotate the indication device 104 will transition from on to off. When the individual indication devices 104, 106, 108 transition on, the configurable display 115 will indicate further information. This may include the name of the destination, its latitude, longitude, altitude, and estimated time of arrival to name a few. The traveler may then continue to rotate and identify another destinations or waypoints in the same manner. As the traveler travels, he may check the orientation of geographic north, destination or home as frequently as he desires in this manner.

Returning to the case of the lost turkey hunter, we can see the utility of the guidance device. Of course the other travelers can benefit as well. For instance before the a group expedition starts their trek, the travelers' program in a safe meeting point If one gets lost the invention can guide them to this point, even in inclement weather. A coal miner lost in a mine would benefit from this invention, preventing him from traversing down blind exits while finding his way out This will be a great device for children as well. Of course if Hansel and Gretel had this invention, the birds eating Hansel's carefully placed guidance bread crumbs wouldn't matter and we would have a different story to tell. The discrete transition indication devices, which are humanly perceptible, in this case USD's, 104, 106, 108 are virtual devices. One of ordinary skill in the art may choose an acoustic device, visual display devices such as light emitting diodes, liquid crystal displays, incandescent lamps as well as tactile transducer

devices such as a motor with a rotating weight, a pendulum, a piezoelectric transducer to name a few. In fact an acoustic device has utility where the user is inconvenienced by looking at the display. This may be very valuable in the military or hunting environments. While we describe a guidance device 101 with three indicators 104, 106, and 108 it would be obvious to one of ordinary skill in the art to reduce this to 1 device with a plurality of discrete states. For instance a light emitting diode that transitions to red when the guidance device 101 is aligned to the geographic north, green when ifs aligned to home and amber when aligned with the destination. Of course other means such as acoustic devices could work in a similar manner.

While FIG. 1 illustrates the relationship between the guidance device's axis and the vectors to geographic north 123, the user heading, 121 and to destination or waypoint 125, FIG. 2 further discloses the details of the invention.

In FIG. 2 we find an antenna 201 coupled to a radio navigation receiver 203, deriving position information, preferably a GPS receiver such as the Magellan C/A code module, available from Magellan Systems Corporation, 260 E. Huntington Dr. Monrovia, CA 91016 (818) 358-2363. Alternatively the radio navigation receiver architecture such as Loran-C, Glonass and others could be substituted for the GPS receiver. The GPS receiver 203 is coupled to the guidance computer 207 through an RS232 serial data link 209. A flux-gate compass 205, such as the one available from Etak Inc., 1430 O'Brien Drive, Menlo Park, CA 94025, (415) 328-3825, is coupled to the guidance computer 207. Of course an alternative bearing indication device may be used for this function. The guidance computer 207 is further comprised of a Motorola 68HC16 microcontroller with an analog to digital converter, a serial data link interface, conventional ROM and RAM. Of course it would be obvious to one having ordinary skill in the art that this guidance computer could be comprised of other available microcontrollers or computers which have similar

attributes. The output of the flux-gate compass 205, is an analog voltage which represents the bearing deviation from magnetic north. The guidance computer 207, applying its analog to digital converter, transforms this information into a binary representation of this for further processing. When considering both latitude and longitude information, derived from the GPS receiver 203, and bearing relative to north derived from element 205, the guidance computer 207 corrects for magnetic anomalies, as illustrated by element 213. The output of element 213 yields an indication of geographic north 215. This information, geographic north 215, and the position information 209, derived from the GPS receiver 203, are then further processed to compute bearing 227, as illustrated by element 217. The keypad 110, is used as described earlier, to enter waypoint position and name information into the guidance computer 207. The configurable display 115, as described earlier, indicates additional information about the desired destination and is controlled by the guidance computer 207. When the appropriate information is entered through the keypad 110 it is stored in the waypoint database 219. This information includes the name or the waypoint, as well a the waypoint position information which includes, but is not limited to, latitude, longitude and altitude. This waypoint information, along with the position information 209 is then used to compute the distance to a desired waypoint position by element 221. And finally, element 223 is a method employed to calculate the appropriate action to be displayed on the guidance display 119 as a traveler desires. The inputs to the process are indication of geographic north, 215, bearing, 227 and waypoint, 225. As indicated earlier, if the bearing of the guidance device 101 axis is geographic north the north indicator, 108 transitions on. As the traveller moves the guidance device 101 away from this vector the north indicator 108 transitions off.

It is the intention of the preferred embodiment that the elements internal to the guidance computer 207 indicated by

elements 213, 217, 221, and 223 are software elements embedded in the Motorola 68HC16 microcontroller, performing the necessary work to accomplish the task at hand. It would be obvious to one of ordinary skill in the art, that this could be accomplished many other ways including a pure hardware implementation, or hybrid of hardware and software.

What is claimed is: