PATENT COOPERATION TREATY TITLE: PRECISION GUIDANCE AND POSITION REPORTING SYSTEM INVENTORS: PATRICK J. NYSTROM MARK NYSTROM

CITATION TO PARENT APPLICATION This Patent Cooperation Treaty Application claims priority to U.S. Provisional Application, Serial No. 60/828,666, filed 9 October 2006. BACKGROUND OF THE INVENTION 1. Field of the Invention: The present invention relates to guidance and positioning systems, and in particular to those involving laser-based data acquisition and measurement systems.

2. Background Information: Positioning multiple, relatively moving objects present challenges in many contexts where the operator(s) of such objects cannot directly observe the necessary actions and reactions of the objects. The most complex, high-stakes "blind" positioning tasks involve such things as docking spacecraft. Perhaps the most mundane of such tasks might be considered the aligning the hitch ball of one' s personal vehicle for engaging the hitch of a utility trailer, boat, or camper. But for the use of "spotters", other tasks that would fall within the category of "blind" positioning tasks would include positioning aircraft at designated locations at airports, positioning long-haul trailers at receiving docks, aligning vehicles on loading ramps or rails (such as loading military vehicles for transport on cargo aircraft), ship positioning in "tight" dock settings, precise placement of equipment

by helicopters (such as large air conditioning units atop tall buildings), positioning cargo containers on cargo ships or transport trucks, and many other similar tasks. To be sure, there already exist systems and devices for measuring and remotely reporting distance or relative positions of multiple, related objects or bodies. However, such existing systems either lack accuracy to a degree of rendering them useless for all but reporting very generalized position information, or involve technology and designs which are so costly as to render them out of reach for all but the most sophisticated users (NASA, for example). There exists considerable unmet need for precise, accurate and affordable guidance and positioning systems which remotely report (substantially in real-time) the relative movements and positions of moving objects to operator(s). Hundreds of thousands of utility trailer, personal boat and camper owners alone would benefit from the availability of such systems. Were there to be a truly affordable and highly precise position guidance system for docking trailers, one which somehow remotely reported hitch ball and hitch relative positions to the car or truck driver who cannot directly observe the relative movement and positions of the ball and hitch, and which would be well within the reach (economically) of average consumers, repeated trial and error, repeated vehicle ingress and egress, the use of spotters, and/or occasional vehicle damage could be eliminated as a part of today's reality of owning or using towed vehicles. Furthermore, were such systems to become available (at any reasonable price), businesses could protect their physical assets by allowing the precise positioning of moving units (airplanes, trucks, trailers, ships, and other equipment) by insuring that the personnel most capable of controlling the units (pilots, drivers, ship captains, etc.) could view precise, real-time data which would indicate present movement and position of the relevant units to, in turn, indicate the control input needed to guide one or both units into the ultimately desired relative juxtaposition.

Such systems might also be integrated into artificial intelligence-based robotics systems which, rather than requiring "training" or cumbersome programming as is presently common, could simply "watch for themselves" the proper positioning of their tooling arms relative to components on which they are to carrying out a physical manipulation. Such applications could be found in the rapidly expanding robotics manufacturing contexts, as well as in unmanned space travel contexts, robotic surgical procedures, and certain military field operations. Over the years many have attempted to meet the above-described needs through a variety of technologies, but with little practical or commercial success. Inventions in this field range from the simplistic to the exceedingly complex. For example, Lockwood (US Patent No. 5,669,621) discloses a simplistic approach to docking a tow vehicle with a trailer involving a combination of flags, which guide the driver to the location for proper hitching. Of course, the accuracy of such a system is limited to the visibility conditions as well as the skill and experience of the driver. On the other end of the spectrum is Capik et al. (US Patent No. 6, 176,505), which requires a combination of two different colored light sources that intersect when the tow vehicle and trailer are aligned. Again, this system is clearly limited to optimal visibility conditions, such that the colored lights are actually visible to the driver. Finally, the closest known predecessor to the present invention is embodied in an alternative system disclosed in Capik et al., wherein a light source mounted on the trailer projects downward onto a sensor plate surrounding the trailer hitch on the tow vehicle. The location is then relayed into the cabin to guide the driver. This device increases the complexity and cost of the system, not only by requiring a significantly complex sensor plate filled with photoelectric sensors, but it also requires an external power source to power the light source stationed on the trailer. Furthermore, the alternative Capik et al. system fails to provide any feedback to the driver until the driver is within the zone of the sensor plate, which in practice, may only be a few inches.

SUMMARY OF THE INVENTION In view of the foregoing, it is an object of the present invention to provide a remote position and motion reporting system. It is another object of the present invention to provide a remote position and motion reporting system which more accurately reports position and position changes than any presently available guidance or reporting system. It is another object of the present invention to provide a remote position and motion reporting system which more precisely reports position and position changes than any presently available guidance or reporting system.

device for tow vehicle coupling alignment that allows the driver to stay inside of the cabin of the tow vehicle throughout the alignment proces s . It is another object of the present invention to provide a remote position and motion reporting system which more rapidly reports position and position changes than any presently available guidance or reporting system. It is another object of the present invention to provide a remote position and motion reporting system which, while presenting improvements in performance over present, analogous systems, is of a design which renders manufacturing costs much lower than even lesser systems. It is another object of the present invention to provide a remote position and motion reporting system which, because of performance capabilities, obviates or lessens the need for, or sole reliance upon human spotters, even in the contexts of maneuvering high value assets. It is another object of the present invention to provide a remote position and motion reporting system which more accurately reports position and position changes than any presently available

guidance or reporting system, even in over-all limited visibility situations (rain, blowing dust, fog, etc.). It is another object of the present invention to provide a remote position and motion reporting system which enhances safety by accurately, remotely reporting position and position changes of moving assets to operator(s) thereof in limited visibility or no visibility contexts to thereby facilitate enhanced responsiveness of such operators in maneuvering moving assets, such as trucks, automobiles, aircraft, trailers, and ships. In satisfaction of these and other related objectives, the present invention provides a remotely reporting position and motion measurement system which more accurately, more precisely, and more quickly reports position and position changes than any presently available guidance or reporting system, and is of a design which permits economical manufacture and customer acquisition. The present remotely reporting position and guidance system was initially developed for use in docking vehicles with to-be-towed trailers, boats, campers and the like, and much of the discussion to follow makes references in that regard. However, once the accuracy, precision, low cost to manufacture and durability of the herein described design became clear, a multitude of other uses became apparent, and the present invention is of the core system, not merely of a trailer docking system or method. The preferred embodiment of the present invention, for the originally intended use in docking vehicles with towed vehicles, incorporates a scanner mounted on or near the bumper of the tow vehicle, one or more targets on or near the trailer hitch of the to-be-towed vehicle, and a display device which resides inside the tow vehicle cabin. One breakthrough technology aspect of the present invention lies in its use of a single scanner unit with a passive, low-cost, reflective target, rather than requiring two actively interacting

units. The scanner unit of the present invention includes a laser emitting source and receiver and signal processing components which, upon receiving light reflected from a target (spaced apart retro- reflective material segments, in the preferred embodiment), generates data which, in turn, is processed and transmitted to a remote reporting unit to indicate (in human perceptible form) information indicative of the relative positions of the scanner and its "target." As will be described in more detail below, the preferred embodiment of the present invention may be calibrated, whereby the scanner and the target can be placed in any relative position which can be defined as the desired ultimate position of the two items. Therefore, one can, for example, place both a scanner unit and a target in any convenient location respectively on a tow vehicle and a to-be-towed unit, move the units into docked position, calibrate the scanner unit for such relative positions of the scanner and target to be interpreted as the docking position, and, even though the scanner unit and target may not actually be closely juxtaposed in these positions, such will be reported as such (and relative distances therefrom reported accordingly) for any subsequent movement of the units . For certain uses, if scanner and target will always be in substantially identical relative positions when relatively moving assets reach their desired positions, units may be pre-calibrated without the need for actually attaching the scanner and target to determine the calibration "zero point." Use in positioning airliners at airport gates, with scanner units being placed at known positions relative to where the nose gear of the aircraft are desired to be is one such example. For example, the position of the nose gear (or some other airframe component) of a Boeing 737 relative to any fixed point in the gate area when the aircraft is properly positioned will not change from one 737 to another. Therefore, pre-calibrated scanners can be installed at pre-determined gate locations, and targets can be installed on predetermined positions on all aircraft of like make and model, with reporting units being installed in the cockpits.

In the preferred embodiment of the present invention, for use in most vehicle docking operations, the location information is conveyed to the remote display device digitally by means of Radio Frequency (RF) energy, delivered either over the tow vehicle's wiring system or by near field radiation. The display device is a small flat panel display consisting of a cross-hair of light emitting diodes (LED), which indicate distance on the vertical axis and left/right position on the horizontal axis A separate LED indicates when position information cannot be determined for indicating to the driver that the scanner lens needs cleaning, and the display device may also contain a speaker which emits tones to assist the driver in the alignment process. The remotely reporting position and guidance system of the present invention meets every object stated above, and will afford users with convenience, safety, economy of acquisition and use, and efficiencies never before realized in the context of maneuvering relatively moving assets.

BRIEF DESCRIPTION QF THE DRAWINGS Applicant's invention may be further understood from a description of the accompanying drawings, wherein unless otherwise specified, like referenced numerals are intended to depict like components in the various views. Figure 1 is a top plan view of the apparatus of the present invention as installed on a tow vehicle / trailer combination. Figure 2 is a front, side, and top cross- sectional view representing the functionality of the scanner of the present invention Figure 3 is a schematic of the scanner circuit board of the present invention. Figure 4 is side view of the display device of the present invention. Figure 5 is a front view of the display device of the present invention. Figure 6 is a schematic of the display device electronics of the present invention.

Appendix A describes the novel mathematical calculations involved in permitting operation of a system of the present design. DETAILED DESCRIPTION QF THE PREFERRED EMBODIMENT Figure 1 depicts an overview of one embodiment of a remotely reporting position and guidance system of the present invention (this one for aligning a tow vehicle 10 and a trailer 22). Tow vehicle 10 has a bumper 12 and a ball hitch 14. Scanner 16 is removably mounted to bumper 12 either directly or via optional bracket member 28, and display device 18 is removably mounted in tow vehicle cabin 20. Trailer 22 has a ball receiver 24, which must couple with ball hitch 14. Target 26 is mounted in proximity to ball receiver 24. In operation, scanner 16 sweeps a laser beam across target 26, and using reflected energy from target 26, scanner 16 determines its relative position to target 26. Scanner 16 is pre-programmed with relative offset positioning between target 26 and ball receiver 24 as well as offset positioning between scanner 16 and ball hitch 14, such that the exact position of ball hitch 14 relative to ball receiver 24 is determined. Scanner 16 then sends a signal to display device 18 either by radiating an RF signal or via existing tow vehicle 10 wiring to display the determined relative positioning. As previously mentioned, scanner 16 may either be directly mounted to tow vehicle bumper 12 via either permanent or temporary means as known in the art. Alternatively, bracket 28 may be permanently mounted to tow vehicle bumper 12, such that scanner 16 may be removably attached to bracket 28 in any number of methods and configurations as would be obvious to one skilled in the art. A diagrammatical view of the preferred embodiment of scanner 16 and its method of operation is presented in Figure 2. Referring to Figure 2, laser 100 is mounted in laser mounting block 101 and emits a beam through collimating hole 119. Laser 100, in the preferred embodiment, is a low-power semiconductor laser operating at a wavelength of 635-650 nm and a power of 1-5

mw. Such lasers are common in hand-held pointing devices and do not present undue safety hazards in ordinary use. More powerful lasers may be used in contexts requiring more relatively distant placement of scanner 16 and target 26. Further, in the preferred embodiment, collimator hole 119 is molded into laser mounting block 101 and blocks extraneous radiation from the beam path. Semiconductor lasers, such as that used in the preferred embodiment of the present invention, typically produce an elliptical spot -with some scattered radiation around the beam. Collimating hole 119 blocks all but the center of the beam, thereby reducing non-aligned light energy and reducing the size of the beam which strikes target 26. Correspondingly, the smaller the beam size which can be achieved at target 26, the more accurately the beam' s entry and exit times can be ascertained. Still referring to Figure 2, the beam next passes through hole 102 in lens 103 and onto mirror 104. Lens 103, in the preferred embodiment, is an inexpensive plastic type lens such as those used in disposable cameras. Hole 102 in lens 103 allows the laser beam to pass through the lens without being refracted by the lens. If the laser beam were to pass through the lens material, it would disperse and fail to accomplish its function of detecting target 26. Mirror 104 is a front- surface mirror which reflects the laser beam toward target 26 and moves the beam across target 26 as it is rotated by motor Ml . Mirror 104 can be rectangular or elliptical; however, mirror 104 must be sized and shaped to match that of lens 103 such that paraxial rays projected upward from mirror 104 all strike lens 103. Lens 103 is suspended by lens bracket 113, which is mounted onto scanner baseplate 122. Mirror 104 is attached to shaft of motor Ml, which is also mounted to swing 109. Motor Ml, in the preferred embodiment, is a small DC motor with appropriate gearing such that the output shaft rotates between 600 and 1200 rpm, depending on the voltage applied. Motor Ml rotates mirror 104 such that the laser beam is swept 360 degrees at an appropriate speed. Shaft encoder wheel 107 is

rigidly attached to mirror mount 105, which is in turn rigidly attached to the motor shaft. Shaft encoder wheel 107 thus rotates with mirror 104. Shaft encoder wheel 107 has projecting teeth which pass through sensing slot of optical slot encoder 108. Optical slot encoder 108 is a commonly available device which contains an infrared LED on one side of the slot and a photodetector on the other side of the slot. When the beam from the infrared LED is broken, the photodetector current changes. Referring to Figure 2, when projecting teeth of shaft encoder wheel 107 pass through slot of optical slot encoder 108, electrical pulses are generated at the output pins of optical slot encoder 108, which in turn are processed by circuit board 123. hi the preferred embodiment, there are 36 projecting teeth which allow the motor shaft's position to be read with an absolute accuracy of 10 degrees (360 degrees / 36 pulses per revolution.) Two consecutive teeth of shaft encoder wheel 107 are missing and allow for the detection of a fixed point in the rotation of mirror 104. The beam then exits scanner 16 through window 121 and scans across target 26. Window 121 allows transmitted and reflected laser energy to pass but keeps environmental contaminates away from the inside of enclosure 120. Target 26 is a retro-reflective surface which reflects light back along its angle of incidence. At this point, energy is reflected back to scanner 16 to mirror 104.. Mirror 104. reflects the returned energy from target 26 toward lens 103. Lens 103 collects the laser energy returned from target 26 and focuses it on photodiode Dl, which is mounted to photodiode block 115, which served to hold photodiode Dl at the focal point of lens 103. The diameter of lens 104 limits the sensitivity of scanner 16, in that, the greater lens 104 aperture, the more light energy it delivers to photodiode Dl; hence, the greater the diameter of lens 103, the more distant target 26 that scanner 16 can detect. However, Applicant has established that a lens 103 of smaller than Vi inch diameter adequately collects light from target 26 at twenty feet. Additionally, the beam must initially pass through hole 102 in lens 103 as closely as possible to the optical axis of lens 103 since most of the reflected

energy will travel back along the beam path and since the intensity of the reflected energy drops off quickly as the optical axis of the scanner (that is, the axis through the center of lens 103 and photodiode Dl) is moved off of the beam axis. Therefore, since photodiode Dl must be on the optical axis, hole 102 must be located just slightly off-center in lens 103 This allows the beam to be placed as closely as possible to the optical axis of lens 103, thus, the maximum intensity of reflected energy is delivered back to photodiode Dl In the preferred embodiment, photodiode Dl is a PIN photodiode which is sufficiently sensitive to 635-650 nm laser energy. When properly biased, photodiode Dl converts light energy into electrical current in proportion to the light intensity Next, circuitry on circuit board 123 amplifies the reflected eneigy, converts the reflected energy to pulses, measures the timing of the pulses, and calculates the relative distance and offset between ball hitch 14 and ball receiver 24 Motor Ml, shaft encoder wheel 107, mirror pedestal 105, and mirror 104 are mounted in swing 109, which is hinged at points 124 and 125 to mounting posts 117 Swing 109 can thus rotate relative to the rest of the assembly such that the laser beam scan line projected by mirror 104 can be moved up or down This is accomplished by means of servo 110 which converts a control signal from circuit board 123 into an angle to which control horn 111 will be set Control horn 111 is coupled by rigid control wire 112 to swing 109 such that when control horn 111 rotates, force is transmitted to swing 109 which causes it to move forward or back relative to the fixed portion of the assembly, thus allowing the laser beam scan line to be moved up or down This allows scanner 16 to locate target 26 at a variety of mounting heights or coupling locations Further, circuit board 123 contains the circuitry required to control the laser and motor as well as receive, piocess, and relay position information The functionality of circuit board 123 is represented in the electrical schematic of Figure 3 Referring to Figure 3, simple power supply circuit U5 takes as its input the +12 to +15V potential generated by the tow vehicle's electrical

system and generates appropriate lower-potential supplies for the rest of the circuit. Alternatively, scanner 16 may be powered by an internal battery; thus, installation would be simplified by eliminating any connection to tow vehicle 10 existing electrical system. Processor U3 has outputs PWMl, PWM2, PWM3, SPIl, and 01, and inputs ECAPl, ECAP2, and A/Dl. Processor U3 is powered by a Vsupply output of power circuit U5. Processor U3 has an external crystal timebase with an internal phase-locked loop which multiplies the external crystal frequency to an appropriate speed for processing. Output PWMl controls the gate of N-channel MOSFET Ql, the drain of which is connected to motor Ml. Output PWMl acting through N-channel MOSFET Ql allows processor U3 to switch motor Ml on and off. By rapidly pulsing PWMl on and off, processor U3 can control the speed of motor Ml . A similar circuit is formed with output PWM2 and N-channel MOSFET Q2, which allows processor U3 to turn laser module LMl on and off as well as control laser module LMl output power. Reflected laser energy form target 26 is focused onto photodiode Dl which is reverse biased into the virtual ground at the inverting input of operational amplifier UlA. UlA and UlB are separate amplifier stages in the same chip. When laser energy strikes photodiode Dl, current proportional to the received energy is produced by photodiode Dl . This current is impressed upon the inverting input of UlA. The output of UlA must supply enough current through resistor Rl to exactly offset the current produced by photodiode Dl. This feedback current is fed through resistor Rl and is thus converted to a voltage proportional to the energy received by photodiode Dl. Capacitor Cl stabilizes UlA by bypassing Rl when the inverting input changes rapidly and must have approximately as much capacitance as the junction of photodiode Dl. The output of UlA is fed to the inverting input of UlB, another operational amplifier stage acting as a comparator, and also input A/Dl of processor U3. Light falling on Dl will be the sum of the ambient light and reflected laser energy. Processor U3 controls laser LMl and can turn the laser off during selected revolutions of motor Ml. Input A/Dl of processor U3 is an analog to digital converter input, which means that

processor U3 can read the voltage level from the output of UlA at its input AfDl. With laser LMl turned off, processor U3 reads the voltage level at input A/Dl and stores this number as the present ambient light level. Processor U3 then uses this value to generate a control message to output SPIl, which in turn causes digital analog converter U2 to produce a voltage level on its OUT pin. This voltage level is presented to the non-inverting input of comparator UlB through resistor R2. Resistor R3 when combined with resistor R2 form a positive-feedback hysteresis circuit which serves to prevent comparator UlB from oscillating. The output of amplifier UlA is compared to the reference voltage produced by D/A converter U2 to produce a digital output which is T when the laser scans across the target and '0' when only ambient light is present at photodiode Dl. This digital output is connected to processor U3's input ECAPl . Processor U3 contains an Edge Capture Unit which can determine the exact time that input ECAPl changes states. Since input ECAPl changes states when the laser beam enters or exits target 26, processor U3 thus acquires the information it needs to establish the position of target 26. Again referring to Figure 3, CNl is a 3-pin header which feeds power and a control signal from processor U3 to a standard R/C servo 110. Servo 110 converts control signal from output PWM3 to an angular position which moves swing 109 up and down. Processor U3 controls the signal at PWM3 and uses it to scan the laser beam up and down in order to find target 26. Again referring to Figure 3, CN2 feeds power to and returns signal from slot encoder 108. The output signal of slot encoder 108 is fed to input ECAP2 of processor U3. ECAP2 is an edge- capture input which allows processor U3 to exactly time the passage of shaft encoder wheel 107's teeth as they pass through the slot in slot encoder 108. U3 contains programming which converts the pulses from slot encoder 108, which occur one per 10 degrees rotation of motor Ml, into extremely accurate angles. When the laser beam enters target 26, there is a transition from 0 to 1 on input ECAPl of processor U3. The exact time of this transition is recorded relative to the most recent

pulse from shaft encoder 108. When the next pulse arrives from shaft encoder 108, processor U3 calculates the difference in time between the two shaft encoder pulses. Knowing that this time represents 10 degrees of motor shaft rotation, processor U3 can take the arrival time of the target entry pulse as a proportion of the total time between encoder pulses and determine the shaft angle when the beam entered target 26 accurate to better than l/lOOO" ¹ of a degree. In a similar fashion, processor U3 records the entry and exit times from target 26, which may contain multiple reflective and non-reflective areas. Programmed with the geometry of target 26 (meaning the pattern and exact sizes of the reflective and non-reflective areas of target 26), processor U3 can calculate the position and distance of target 26. For a description of the algorithm developed by the present inventors and used to convert the captured entry and exit angles to distance, see Appendix 1. Once processor U3 has determined the left-πght position and distance of target 26, it converts this information into a short sequence of digitally encoded pulses which are sent via output Ol to RF transmitter U4. RF transmitter U4 is a low-power RF transmitter which operates in the 418 MHz band A small antenna ANTl is attached to RF transmitter U4 which allows it to radiate its RF signal to display device 18 mside tow vehicle cabin 20 Alternatively, information may be transmitted from scanner 16 to display device 18 by sending low-level RF over the existing wiring system of tow vehicle 10. Referring back to Figure 2, in the preferred embodiment, pushbutton 118 serves two functions First, when scanner 16 is inactive, pushing pushbutton 118 activates scanner 16, at which time the laser beam begins scanning target 26 and transmitting data to display device 18. Secondly, when scanner 16 is active, pushing and holding pushbutton 118 for two seconds or longer will store the present target 26 location as the 'home' position. This information is stored in the form of two offsets, one for left-right distance and one for back-front distance, into non-volatile memory within processor U3. Referring back to Figure 1, m operation, this procedure should be performed once

after scanner 16 is mounted to tow vehicle bumper 12 and with trailer 22 already coupled to tow vehicle 10. Hence, the system 'learns' the target 26 mounting location relative to ball receiver 24 (the "zero point") and can determine how far ball hitch 14 is from its coupled position with ball receiver 24. Referring to Figure 4, in the preferred embodiment, display device 18 consists of display panel 310, visor clip 312, power cable 314, and power connector 316. Display panel 310 attaches to a rearview mirror or visor in tow vehicle cabin 20 via visor clip 312. Power cable 314 runs from display panel 310 to 12V power connector 316, which, in turn, plugs into an existing power receptacle in tow vehicle cabin 20. Referring to Figure 5, display device 310 contains two 7-segment LEDs 322 which indicate the distance from scanner 16 to target 26, unit LEDs 318 and 320 which indicate the units being displayed on 7-segment LEDs 322, and an arc of LEDs 324 including a center LED 326 which indicate the left/right approach angle between scanner 16 and target 26 and which function to indicate to driver of tow vehicle 10 which direction he needs to turn to align ball 14 with receiver 24. Lastly, speaker 324 emits tones to assist driver in aligning ball receiver 14 and ball hitch 24. Referring to Figure 6, an electrical schematic of display device 18 is provided. Power supply U6 receives from connector 316 the 12V to 15V potential of tow vehicle's 10 electrical system, and generates the lower operating voltage required by display device 18 circuitry, such as +3.3 V. RF receiver module U7 receives radio transmissions in the 418 MHz band via antenna ANT2. The received digital bitstream comes out of pin 02 of RF receiver module U7 and connects to input INl of processor U8. When a data packet is detected, it is decoded by software in processor U8 which drives the appropriate outputs 03 to light 7-segment LEDs 322 segments, LED arc 324, and unit LEDs 318, 320 to indicate distance and angle to target 26. Resistor R30 is a current limiter of an appropriate value to limit the current through the associated LED or segment. Note that for clarity

only one LED driver is shown; there are many such circuits on the display device which are identical, one for each segment of the 7- segment displays 322 and one for each LED in the arc 324 and one for each unit LED 318 and 320. Output 04 connects to speaker 330 and directly controls the pitch and duration of any tones, which are appropriate to help the driver align tow vehicle 10 and trailer 12 based upon information received from scanner 16 via the radio link. Typical use of the above described invention is envisioned as follows. First, initial setup and programming of the system must take place assuming the system has already been installed. This is accomplished by first aligning and coupling ball hitch 14 of tow vehicle 10 with ball receiver 24 of trailer 22. Next, pushbutton 118 must be pressed to activate scanner 16. Pushbutton 118 must then be pressed and held for two seconds to store the present target 26 location as the home position. The system is now programmed and ready for operation. After tow vehicle 10 and trailer 22 have been disconnected and separated, the present invention may then be used for successive alignment for coupling. At this point, the driver plugs display device 18 into a 12V receptacle in tow vehicle cabin 20 and begins backing tow vehicle 10 for alignment with trailer 22. As scanner 16 detects target 26, a signal is transmitted to display device 18 in cabin 20, which both visually and audibly indicates to driver the relative location of ball receiver 24 with respect to ball hitch 14. The driver merely reacts to the indicators maneuvering tow vehicle 10 until display device 18 indicates alignment has been successful. At this point, tow vehicle 10 and trailer 22 have been properly aligned and are ready for coupling. Although the invention has been described with reference to specific embodiments, this description is meant (as permitted by law) only to serve as an example of the invention which is covered by the patent claims. A wide variety of embodiments of the present invention are possible, including one with additional or substituted features. However, if such embodiments fairly include the essential, basic features of the present invention as listed in any one of the claims, whether or not

they include features differing from those actually shown or described, or additional features not shown at all, then (as prescribed by law) the patent claims will encompass such variations, as well as those depicted in this document.