Abstract:
The present invention is a guidance apparatus for movable toy vehicles that includes a track, or roadway, on which the toy vehicles move. The truck has an intersection. The intersection has a magnetic guidance mechanism for steering the toy vehicles in alternate directions through the intersection. An intersection magnetic sensing mechanism, i.e., electromagnets at the intersection and magnets in the vehicles, stops the vehicles prior to entering the intersection. Additionally, the vehicles stopped at the intersection can be actuated by a timing mechanism after passage of a predetermined time period. Furthermore, the vehicles stopped at the intersection can be actuated only after a mechanism for sensing vehicle presence in the intersection senses no vehicles in the intersection.

Description:
RELATED APPLICATION(S) INFORMATION 
     This is a continuation of U.S. application Ser. No. 08/943,545, filed Oct. 3, 1997 now abandoned, the disclosure of which is hereby expressly incorporated by reference. 
    
    
     FIELD OF THE INVENTION 
     The invention relates to the guidance of toy vehicles and, more particularly, electromagnetic guidance thereof on a predefined track. 
     BACKGROUND OF THE INVENTION 
     U.S. Pat. No. 1,084,370 discloses an educational apparatus having a transparent sheet of glass laid over a map or other illustration sheet that is employed as a surface on which small moveable figures are guided by the movement of a magnet situated below the illustration sheet. Each figure, with its appropriate index word, figure or image is intended to arrive at an appropriate destination on the top of the sheet and to be left there temporarily. 
     U.S. Pat. No. 2,036,076 discloses a toy or game in which a miniature setting includes inanimate objects placeable in a multitude of orientations on a game board and also includes animate objects having magnets on their bottom portions. A magnet under the game board is employed to invisibly cause the movement of any of the selected animate objects relative to inanimate objects. 
     U.S. Pat. No. 2,637,140 teaches a toy vehicular system in which magnetic vehicles travel over a toy landscape as they follow the movement of ferromagnetic pellets through an endless nonmagnetic tube containing a viscous liquid such as carbon tetrachloride. The magnetic attraction between the vehicles and ferromagnetic pellets carried by the circulating liquid is sufficient to pull the vehicles along the path defined by the tube or channel beneath the playing surface. 
     U.S. Pat. No. 3,045,393 teaches a device with magnetically moved pieces. Game pieces are magnetically moved on a board by reciprocation under the board of a control slide carrying magnetic areas or elements longitudinally spaced apart in the general direction of the motion path. The surface pieces advance step-by-step in one direction as a result of the back and forth reciprocation of the underlying control slide. 
     U.S. Pat. No. 4,990,117 discloses a magnetic force-guided traveling toy wherein a toy vehicles travels on the surface of a board, following a path of magnetically attracted material. The toy vehicles has single drive wheel located centrally on the bottom of the vehicle&#39;s body. The center of the gravity of the vehicle resides substantially over the single drive wheel so that the vehicles is balanced. A magnet located on the front of the vehicles is attracted to the magnetic path on the travel board. The magnetic attraction directly steers the vehicle around the central drive wheel along the path. 
     SUMMARY OF THE INVENTION 
     The present invention is a guidance apparatus for moveable toy vehicles that includes a track, or roadway, on which the toy vehicles move. The track has one, and preferably more than one, intersection. The intersection has a magnetic guidance mechanism for steering the toy vehicles in alternate directions through the intersection. An intersection magnetic sensing mechanism, electromagnets at the intersection and magnets in the vehicles, stops the vehicles prior to entering the intersection. Additionally, the vehicles stopped at the intersection can be actuated by a timing mechanism after passage of a predetermined time period. Furthermore, the vehicles stopped at the intersection can be actuated only after a mechanism for sensing vehicle presence in the intersection senses no vehicles in the intersection. Preferably, the guidance mechanism for steering toy vehicles through an intersection includes an electromagnet under each roadway of the intersection. Each electromagnet has a pair of poles that straddle the path of the toy vehicle. The toy vehicle has a magnet on its undersurface. Each of the electromagnets under the roadways is actuatable for current to flow in each of two directions through the electromagnet for each of the two poles of the electromagnet to be either a positive or a negative pole. The two poles of each electromagnet can thus either attract or repel the pole of the magnet on the underside of the vehicle, depending on the direction of current flow through the electromagnet. Since the two poles of the electromagnet straddle the path of the toy vehicle, when energized, one pole will attract and the other pole will repel the vehicle magnet to guide the vehicle in a first direction (i.e., right). Reversing the current through the electromagnet reverses the polarity of the two poles, thus guiding the vehicle in the opposite direction. No current flow through the electromagnet results in no magnetic interaction with the vehicle, and the vehicle proceeds straight. 
     Preferably, a surface roadway is located over the track or roadway described above. Additionally, a surface toy vehicle is movable on the surface roadway in reaction to movement under this surface toy vehicle of the toy vehicle (i.e., powered subsurface vehicle) on the track or roadway under the surface roadway. Each powered subsurface vehicle has a motor therein and a collision avoidance mechanism. The collision avoidance mechanism includes a magnet on the rear of each of the subsurface vehicles and a magnetic field sensor on the front of each of the subsurface vehicles. The magnetic field sensor is adapted to de-energize the power source of the associated subsurface vehicle when the magnetic field sensor senses the magnetic field of the magnet of another subsurface vehicle located ahead of the subsurface vehicle. In this manner, following subsurface vehicles stop prior to impact with leading subsurface vehicles. A similar type of Hall effect system, with a magnet on the vehicles and a sensor adjacent the intersection can determine when a vehicle is approaching the intersection. A vehicle approaching an intersection can be stopped by one of the electromagnets adjacent each roadway that function to electromagnetically block intersection access on command. 
     Preferably, guidance of the toy vehicles through the intersection can be accomplished with a remote control that provides vehicle guidance instructions to the electromagnetic guidance mechanism of the intersection. Alternatively, the electromagnetic guidance mechanism of the intersection can be preprogrammed to guide the toy vehicles through the intersection on, for example, a random basis. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing aspects and many of the attendant advantages of this invention will become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein: 
     FIG. 1 is an isometric view of a toy building set including the upper roadway and lower roadway of the present invention; 
     FIG. 2 is a diagrammatic section view of the upper roadway, lower roadway, surface vehicle and powered subsurface vehicle of the present invention; 
     FIG. 3 is a partially exposed isometric view of the powered subsurface vehicle of the present invention; 
     FIG. 4 is a diagrammatic section view of attractive forces between two magnets showing no offset; 
     FIG. 5 is a diagrammatic section view of attractive forces between two magnets showing horizontal offset. 
     FIG. 6 is a diagrammatic plan view of the magnetic interaction between the surfaces vehicle and the subsurface vehicle of the present invention during straight movement. 
     FIG. 7 is a diagrammatic plan view of the magnetic interaction between the surface vehicle and the subsurface vehicle of the present invention during a turn; 
     FIG. 8 is an electrical schematic of the control circuit of the subsurface vehicle of the present invention; 
     FIG. 9 is a plan view of a leading subsurface vehicle and a following subsurface vehicle showing collision avoidance thereof; 
     FIG. 10 is a transverse section view of the upper roadway, lower roadway, two surface vehicles and two powered subsurface vehicles of the present invention; 
     FIG. 11 is a diagrammatic side section view of the upper roadway, lower roadway, surface vehicle and powered subsurface vehicle of the present invention; 
     FIG. 12 is a plan view of the lower roadway of the present invention with electromagnetic direction controllers; 
     FIG. 13A is a detail view of the electromagnetic direction controllers of FIG. 12; 
     FIG. 13B is a partially exposed isometric view of the electromagnetic direction controllers of FIG. 12; 
     FIG. 14 is a detail plan view of FIG. 12 showing the electromagnetic direction controllers of the present invention; 
     FIG. 15 is a diagrammatic section view of the interaction between the guidance control elements located adjacent an intersection and on the subsurface vehicle of the present invention; and 
     FIG. 16 is an electrical schematic of the guidance control electronics of the intersection of FIG. 12 of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The present invention is a toy vehicular electromagnetic guidance apparatus as shown and described in FIGS. 1-16. As best shown in FIG. 1, the toy vehicular guidance apparatus of the present invention can be used in a toy building set  2  having a lattice  4  and modular bases  6 . More specifically, lattice  4  provides the substructure of toy building set  2  and supports modular bases  6  which are spaced above lattice  4  by a predetermined distance. Lower roadway  8  is also supported by lattice  4 , but on a lower portion of lattice  4  at a predetermined distance below modular bases  6 . Upper roadway  10  is comprised of some of modular bases  6  that have been specialized in design to provide a smooth traffic bearing surface for movement of surface vehicles  12  thereon. Most preferably, the road pattern of upper roadway  10  and lower roadway  8  are identical so that subsurface vehicles  14 , as shown in FIGS. 2 and 3, can travel on lower roadway  8  to guide surface vehicles  12  on upper roadway  10  in a manner further described below. Preferably, the distance between lower roadway  8  secured to lattice  4  and upper roadway  10 , also secured to lattice  4 , is large enough to allow ingress and travel of subsurface vehicle  14  between lower roadway  8  and upper roadway  10 . 
     Next referring to FIG. 2, the magnetic interconnection between surface vehicle  12  and subsurface vehicle  14  is shown whereby subsurface vehicle  14  travels between lower roadway  8  and upper roadway  10  such that surface vehicle  12  can be transported on upper roadway  10  by subsurface vehicle  14 . As shown in FIG. 2, power supply  16  interconnects a lower conductive layer  18  and upper conductive layer  20 . Lower conductive layer  18  is located on the upper side of lower roadway  8 . Upper conductive layer  20  is located on the under side of upper roadway  10 . Power supply  16  thus energizes lower conductive layer  18  and upper conductive layer  20 . Subsurface vehicle  14  accesses the electrical power in lower conductive layer  18  and upper conductive layer  20  in a manner described below to travel on lower roadway  8 . Power supply  16  can be either direct current or alternating current, of preferably a shock safe voltage level, for example, about 12 volts. Lower conductive layer  18  and upper conductive layer  20  consist of thin metal sheets, foil layers or a conductive coating that may be, for example, polymeric. The conductive sheet, coating, or composite most preferably includes copper as the conductive metal. 
     Still referring to FIG. 2, subsurface vehicle  14  has a chassis  21  with an upper brush  22  located on the top of chassis  21  adjacent the under side of upper roadway  10  on which upper conductive layer  20  is located. Chassis  21  also has a lower brush  24  located on the under side thereof adjacent the upper surface of lower roadway  8  on which lower conductive layer  18  is located. Upper brush  22  and lower brush  24 , which can be metal, graphite or conductive plastic, provide electrical interconnection between chassis  21  of subsurface vehicle  14  and upper conductive layer  20  and lower conductive layer  18 , respectively for transfer of electrical power from power supply  16  to subsurface vehicle  14 . Upper brush  22  and lower brush  24  are preferably elastic or spring loaded in order to accommodate changes in the distance between upper conductive layer  20  and lower conductive layer  18  to ensure a reliable electrical connection to subsurface vehicle  14 . Upper brush  22  and lower brush  24  each have a head  25  that is contoured, or in another way shaped, for low friction sliding along upper conductive layer  20  and lower conductive layer  18  respectively, when subsurface vehicle  14  is in motion. Lower conductive layer  18  and upper conductive layer  20  can be located on substantially the entire upper surface of lower roadway  8  and under side of upper roadway  10 , respectively, in order to ensure electrical interconnection of subsurface vehicle  14  to power supply  16  despite lateral movement across lower conductive layer  18  and upper conductive layer  20  by subsurface vehicle  14  due to, for example, turning of subsurface vehicle  14  or uncontrolled lateral movement thereof. Alternatively, lower conductive layer  18  and upper conductive layer  20  can be located in troughs or grooves in the upper surface of lower roadway  8  and the under side of upper roadway  10 , respectively, into which head  25  of lower brush  24  and head  25  of upper brush  22 , respectively, can reside in order to control the tracking of subsurface vehicle  14  in an electrically conductive environment by minimizing lateral movement of subsurface vehicle  14  relative to lower roadway  8  and upper roadway  10 . Upper brush  22  and lower brush  24  are both electrically connected to control circuit  26  that is located on the front of chassis  21  of subsurface vehicle  14 . Generally, control circuit  26  controls the electrical functioning of subsurface vehicle  14 , and more specifically controls, and is electrically interconnected with, electromotor  28 . Control circuit  26  thus controls the direction of movement, acceleration, deceleration, stopping, and turning of subsurface vehicle  14  based on external control signals, or control signals generated by subsurface vehicle  14  itself. Control circuit  26  is described in further detail below in conjunction with FIG.  8 . Electromotor  28 , electrically interconnected with control circuit  26 , can be a direct current motor with brushes, a direct current brushless motor, or a stepper motor. Electromotor  28  is mechanically interconnected with transmission  30  that transfers rotation of electromotor  28  to drive wheel  32  employing the desired reduction ratio. More than one electromotor  28  can be employed for independent drive of a plurality of drive wheels  32 . Additionally, transmission  30  can be a differential transmission to drive two or more drive wheels  32  at different speeds. In this manner, more sophisticated control of the acceleration, deceleration, and turning, for example, of subsurface vehicle  14  can be employed. Chassis support  34  is located on the under side of chassis  21  of subsurface vehicle  14 . Chassis support  34  is spaced from drive wheel  32 , also located on the under side of subsurface vehicle  14 , and can be, for example, rollers or low friction drag plates that are preferably flexible to allow compensation for distance variation between lower roadway  8  and upper roadway  10 . Magnets  36  are preferably disposed on the top of subsurface vehicle  14  adjacent the under side of upper roadway  10 . Magnets  36  are preferably permanent magnets, but can also be electromagnets supplied with power from power supply  16  via control circuit  26 . 
     Still referring to FIG. 2, surface vehicle  12 , while preferably being a car, truck, or other vehicle, can be any type of device for which mobility is desired in the environment of a toy building set. Surface vehicle  12  includes wheels  38  which are rotatable to allow movement of surface vehicle  12  on upper roadway  10 . Instead of wheels  38 , a low friction drag plate can be employed. Magnets  40  are located on the under side of vehicle  12  adjacent upper roadway  10 . Magnets  40  are sized and spaced on vehicle  12  to be aligned with magnets  36  on the top of chassis  21  of subsurface vehicle  14  for magnetic interconnection of surface vehicle  12  and subsurface vehicle  14 . Magnets  36  are 0.1×0.125 inch round permanent rare earth magnets with residual flux around 9,000 Gauss. Preferably, the same type of magnets are employed for magnets  40  of surface vehicle  12 . Reliable magnetic coupling has been observed at a distance of up to 0.2 inches between magnets  40  of surface vehicle  12  and magnets  36  of subsurface vehicle  14 . 
     Next referring to FIG. 3, a preferred embodiment of subsurface vehicle  14  is shown. Subsurface vehicle  14  of FIG. 3 is designed to move between an ABS lower roadway  8  and with a lower conductive layer  18  and an ABS upper roadway  10  with an upper conductive layer  20 . Subsurface vehicle  14  of FIG. 3 has one drive wheel  32  and two chassis supports  34  having low friction pads  35 . Two upper brushes  22  and two lower brushes  24  are preferably present and are made from copper. Upper brushes  22  and lower brushes  24  are loaded by torsion springs. The above configuration assures a substantially uniform force on drive wheel  32  regardless of the clearance between lower roadway  8  and upper roadway  10 , and also facilitates passage of subsurface vehicle  14  along inclines or declines of lower roadway  8  and upper roadway  10 . Two rear magnets  62  are located on chassis  21  for collision avoidance with another subsurface vehicle  14  as described further below. Electromotor  28  is preferably a direct current brush motor, for example, Namiki model No. 10CL-1202, rated for 0.22 W maximum output at approximately 17,000 RPM at 4.5 volts of direct current power supply. Transmission  30  consists of a Namiki 100A gear train blocked with motor  28  along with a crown gear and associated pinions. The total reduction ratio of transmission  30  is 1:40, and the efficiency is about 25 percent. Subsurface vehicle  14  operates at speeds of up to 9 inches per second at an incline of up to 15°. Lower magnet  64 , on the underside of chassis  21 , guides subsurface vehicle  14 , and associated surface vehicle  12 , on lower roadway  8 , and causes subsurface vehicle  14 , and associated vehicle  12 , to turn based on magnetic interaction with electromagnetic direction controllers adjacent lower roadway  8  described in further detail below. Lower magnet  64  is preferably conic shaped with a protruding tip and is most preferably a 0.5×0.2 inch permanent rare earth magnet with a residual flux of about 9,000 Gauss. The protruding tip  65  of lower magnet  64  is preferably steel for more precise guidance on lower roadway  8 . A pair of Hall effect sensors  67  straddle control circuit  26  on the front of chassis  21  for control of surface vehicle  14  in a manner further described below. 
     Next referring to FIGS. 4-7, the principles of the magnetic forces interconnecting surface vehicle  12  and subsurface vehicle  14  by magnets  36  and magnets  40  are described. As shown in FIG. 4, when two magnets are placed one above the other, with opposite poles toward each other, a magnetic force F z  between them exhibits based on the following equation:          F   z     ≈     6                       M   1     ·     M   2         r   4                                
     where r is the distance between parallel planes in which magnets are situated and 
     M 1 , M 2  are magnetic moments of both magnets. For permanent magnets, M is proportional to the volume of magnetic substance cross its residual flux density. For electromagnets, M is proportional to the number of turns cross the current. 
     As shown in FIG. 5, when two magnets, one above the other, are shifted slightly to be horizontally offset by a distance b, the horizontal force F x  occurs:          F   x     ≈     6      b                       M   1     ·     M   2         r   5                                
     Next referring to FIGS. 6 and 7, the principles described above and shown in FIGS. 4 and 5 are discussed in relation to movement of nonpowered surface vehicle  12  by powered subsurface vehicle  14  due to the magnetic interconnection between magnets  40  of surface vehicle  12  and magnets  36  of subsurface vehicle  14 . First referring to FIG. 6, during straight line movement, the horizontal offset between surface vehicle  12  and subsurface vehicle  14  increases as subsurface vehicle  14  moves until forces F 1  and F 2  become large enough to overcome friction, inertia and, possibly, gravitational incline. At this point, surface vehicle  12  moves to follow subsurface vehicle  14 . During a turn, as shown in FIG. 7, forces F 1  and F 2  have different directional vectors. Thus, forces F 1  and F 2  not only create thrust, but torque as well, that causes surface vehicle  12  to follow subsurface vehicle  14 . 
     Now referring to FIG. 8, control circuit  26  is described in further detail. Control circuit  26  is electrically connected to both upper brushes  22  and lower brushes  24 . Control circuit includes an FET  40  (for example, model No. ZVN4206A manufactured by Zetex) that is normally open because of 10 k Ohm pull-up resistor  42 . However, FET  40  deactivates electromotor  28  if a magnetic control or collision signal is detected by a Hall effect sensor  46  (element  67  of FIG. 3) as further described below. Zener diode  48  (for example, model no. 1N5242 manufactured by Liteon Power Semiconductor) prevents overvoltage of the gate of FET  40 . Diode  50  (for example, model no. 1N4448 manufactured by National Semiconductor), as well as an RC-chain consisting of 100 Ohm resistor  52  and 0.1 mcF capacitor  54 , protect control circuit  26  from inductive spikes from electromotor  28 . Diode  56  (for example, model no. 1N4004 manufactured by Motorola) protects control circuit  26  from reverse polarity of power supply  16 . As shown in FIG. 9, Hall effect sensor  46  (element  67  of FIG. 9) of control circuit  26  is employed to prevent a rear end collision between a leading and a following subsurface vehicle  14 . Control circuit  26  is preferably located on the front of following subsurface vehicle  14  so that Hall effect sensor  67  will be in close proximity to the magnetic field of rear magnet  62  of leading subsurface vehicle  14 . When the following subsurface vehicle  14  closes to a predetermined distance, the magnetic field of rear magnet  62  of leading subsurface vehicle  14  is sensed by Hall effect sensor  67 . Hall effect sensor  67  causes FET  40  to deactivate electromotor  28 , thus stopping the following subsurface vehicle  14 . When the leading subsurface vehicle  14  moves away from the following subsurface vehicle  14 , the increased distance therebetween removes the magnetic field of rear magnet  62  of leading subsurface vehicle  14  from proximity to Hall effect sensor  67  of following subsurface vehicle  14 . FET  40  thus activates electromotor  28  for movement of following subsurface vehicle  14 . 
     Next referring to FIGS. 10 and 11, further structural detail of one embodiment of lower roadway  8  and upper roadway  10 , between which subsurface vehicle  14  travels, is shown. Lower vertical supports  66  are aligned in two spaced apart sets to support horizontal plate  68 , which is preferably comprised of aluminum or other metal alloy. Horizontal plate  68  is the foundation for lower roadway  8 , which is preferably comprised of ABS. As stated above, lower conductive layer  18 , comprised of nickel or other conductive material, is located on lower roadway  8 . Lower brushes  24  are in electrical communication with lower conductive layer  18 . Thus, longitudinal steel strip  69  passes through horizontal plate  68  and is nested in lower roadway  8  at a sufficient depth such that lower magnet  64 , and specifically steel tip  65  thereof, is attracted to steel strip  69  for guidance of subsurface vehicle  14 . Upper vertical supports  74  are preferably spaced apart in two sets. On the upper ends of upper vertical supports  74  is upper roadway  10 , having upper conductive layer  20 , preferably made of nickel or other conductive alloy, on its underside. Bolts  76  are employed to removably secure upper roadway  10  and upper conductive layer  20  to upper vertical supports  74 . Upper vertical supports  74  preferably have a height precisely defined to allow electrical communication between lower brushes  24  of subsurface vehicle  14  and lower conductive layer  18 , as well as between upper brushes  22  of subsurface vehicle  14  and upper conductive layer  20 . 
     Referring to FIGS. 12,  13 A,  13 B and  14 , intersection  82  and the electromagnetic direction control components thereof are shown in detail. As best shown in FIGS. 13A and 13B, an electromagnet  150  is located under each lower roadway  8  where the lower roadway  8  joins with intersection  82 . Each electromagnet  150  is comprised of a U-shaped core  152  with a two section coil  154  thereon. U-shaped core  152  is preferably comprised of low carbon steel and coil  154  is preferably comprised of about 4,000 turns of #40 copper wire. Each electromagnet  150  is connected to an electric power source known in the art such that current in two alternating directions can selectively be passed through coil  154 . In this manner, poles  156  and  158  of U-shaped core  152 , which straddle steel strip  69 , can be configured with either pole  156  being positive and pole  158  being negative, or pole  156  being negative and pole  158  being positive. Poles  156  and  158  can thus either attract or repel the pole of lower magnet  64  of subsurface vehicle  14  adjacent steel strip  69 , depending upon the direction of current flow through electromagnet  150  that has been selected. With current flowing through electromagnet  150  in a first direction, pole  156  will thus attract lower magnet  64  of subsurface vehicle  14  and pole  158  will repel lower magnet  64  to guide subsurface vehicle  14  in a first direction, i.e., right. Reversing the direction of the current through electromagnet  150  will cause pole  156  to repel lower magnet  64  and pole  158  to attract lower magnet  64  to guide subsurface vehicle  14  in a second direction, i.e., left. No current flow through electromagnet  150  results in no magnetic interaction of poles  156  and  158  with lower magnet  64 , and subsurface vehicle  14  proceeds straight. 
     As shown in FIG. 14, in addition to electromagnet  150  and associated poles  156  and  158 , each intersection  82  includes a laser detector  160  that is actuatable by a remote control unit. When actuated, laser detector  160  causes infrared sensor  162  (shown in FIG. 12) of this specific intersection  82  to receive infrared control commands from a remote control unit to selectively control the electromagnets  150  as well as stop coils  164  of the specific intersection  82 . Stop coils  164  are electromagnets located on each lower roadway  8  adjacent intersection  82  that, when energized, actuate Hall effect sensors  67  to deactivate motor  28  of subsurface vehicle  14 , thus stopping subsurface vehicle  14  prior to entering intersection  82  in order to control multiple vehicle traffic. Hall effect sensors  166 , located on each lower roadway  8  adjacent intersection  82 , detect when a subsurface vehicle  14  is approaching intersection  82 . Hall effect sensors  168  also located on each lower roadway  8  adjacent intersection  82 , detect when a subsurface vehicle  14  has left intersection  82 . The data from laser detector  160 , infrared sensor  162 , Hall effect sensors  166  and Hall effect sensors  168  are fed to microprocessor U 1  of FIG. 16 to control intersection traffic, as described below. 
     Referring to FIG. 15, the orientation of stop coil  164 , Hall effect sensor  166  and Hall effect sensor  168  proximate to Hall effect sensor  167  and lower magnet  64  of subsurface vehicle  14  is shown. Hall effect sensor  166  adjacent intersection  82  senses lower magnet  64  of approaching subsurface vehicle  14 . This data is processed by microprocessor U 1  of FIG. 16, below, to activate stop coil  164 . Stop coil  164  triggers Hall effect sensor  67  of subsurface vehicle  14  to deactivate motor  28 , thus stopping subsurface vehicle before it enters intersection  82 . Hall effect sensor  168  detects lower magnet  64  of a subsurface vehicle  14  as it leaves intersection  82  and relays this data to microprocessor U 1 . The above interaction between stop coils  164 , Hall effect sensor  166 , Hall effect sensor  67 , lower magnet  64  and microprocessor U 1  ensures that after one subsurface vehicle  14  has entered intersection  82 , all other subsurface vehicles  14  are detained until that subsurface vehicle  14  has left intersection  82 . 
     The above electromagnetic direction controllers of the present invention can be employed in a random mode whereby a Hall effect sensor  166  of a lower roadway  8  senses the approach of a subsurface vehicle  14 , as described above. Microprocessor U 1  then activates electromagnet  150  of the appropriate lower roadway  8  and randomly selects the current direction (or no current) so the subsurface vehicle  14  will randomly turn left, right or proceed straight through the intersection  82 . When microprocessor first activates electromagnet  150 , all stop coils  164  leading to intersection  82  are energized to block all traffic. After about 100 mseconds, the stop coil  164  of the lower roadway  8  on which the subsurface vehicle  14  to be controlled is located is deactivated by microprocessor U 1  so that the subsurface vehicle  14  can enter intersection  82  to be guided by electromagnet  150 . If more than one subsurface vehicle  14  is present at the intersection, microprocessor U 1  commands them based on their order of arrival at intersection  82 . 
     The above electromagnetic direction controllers of the present invention can be employed in a user control mode employing laser detector  160  and infrared sensor  162  of intersection  82 , described above, to provide specific user command to allow a particular subsurface vehicle  14  to be guided in a specific direction through intersection  82 . This user controlled mode operates substantially the same as the above random mode except that microprocessor U 1  of FIG. 16 does not randomly energize electromagnet  150  of the subject lower roadway  8 . Instead, microprocessor U 1  follows the infrared command signals it has received from infrared sensor  162  to energize electromagnet  150  in the manner directed by the user to accomplish the desired direction of movement of subsurface vehicle  14 . As in the above random mode, all stop coils  164  are first energized, with on subsequently opened. Also, commands are followed by microprocessor U 1  in the order received. 
     Next referring to FIG. 16, the electrical circuitry of the electromagnetic guidance control of intersection  82  is described. All logic functions are performed by an eight-bit microcontroller U 1  (for example, model No. PIC16C65, manufactured by Microchip). Microcontroller U 1  is clocked by a 10 MH quartz crystal X1, for example, model No. A143E manufactured by International Quartz Devices. Voltage monitor U 7 , for example, model No. 1381S manufactured by Panasonic, is responsible for the power-up reset and power supply fault protection. When the logic supply voltage (plus 5 V) drops below 4.2 V, the voltage detector drive LOW the MCLR pin of microcontroller U 1 , thus shutting it down to prevent it from operation at reduced power supply voltage. When the logic supply voltage (plus 5 V) is above 4.2 V, the voltage detector drive HIGH the MCLR pin of microprocessor U 1 , thus resetting it and reinitializing the system. Two full bridge drivers U 5 , for example, model No. UDN2903, manufactured by Allegro, drive electromagnets L 5 , L 6 , L 7  and L 8  (element  150  of FIGS. 13A and 13B) of intersection  82 . When pin ENA of driver U 5  is HIGH, the state of pin PHA determines the direction of the current through the selected electromagnet L 5 -L 8 , and thus the turn direction of a subsurface vehicle  14 . When pin ENA of the full bridge driver U 5  is LOW, no current flows through the selected electromagnet L 5 -L 8  and the substrate vehicle  14  proceeds straight regardless of the state of pin PHA. Stop coils L 1 -L 4  (element  164  of FIGS. 13A and 13B) are driven through Darlington array U 4 , for example, model No. ULN2003, manufactured by Motorola. Another channel of Darlington array U 4  drives a buzzer or other sound device HN 1 , for example, model No. P9948 manufactured by Panasonic that provides user feedback for the hand-held remote control device. Hall effect sensors  166 , described above, are designated H 1 -H 4  and are, for example, model No. HAL506 manufactured by ITT Semiconductors. Hall effect sensors  166  sense when a subsurface vehicle enters intersection  82 . Hall effect sensors  168  are designated H 5 -H 8  in FIG. 16, sense when a subsurface vehicle leaves intersection  82 , and are preferably the same model as Hall effect sensors H 1 -H 4 . When activated by side magnet  64  of a subsurface vehicle  14 , Hall effects sensors H 1 -H 8  drive LOW inputs RB 4 -RB 8  of microcontroller U 1 , then denoting that a subsurface vehicle  14  has entered or left intersection  81 . Since Hall effect sensors H 1 -H 8  are open collector outputs, pull-up resistors R 24 -R 27  are necessary to drive inputs of microprocessor U 1  HIGH when no subsurface vehicle  14  is detected. Laser detector  160 , described above, is denoted as LD 1  and is connected directly to inputs of microprocessor U 1  to provide input as to the desired electromagnetic configuration of intersection  82 . The active level of laser detector LD 1  is HIGH. Infrared sensor  162 , denoted U 6  in FIG. 16, for example, model No. TFM5300 manufactured by Temic, selects the route of subsurface vehicle  14  via the interface of the remote control. The information pertaining to the desired direction of subsurface vehicle  14  from the remote control interface is transmitted serially microprocessor U 1  and is then decoded. The above circuit requires three power supply voltages: +5 V, +15 V, and the voltage of the subsurface vehicle  14  that is adjustable between +3 V and +6 V. 
     While the preferred embodiment of the invention has been illustrated and described, it will be appreciated that various changes can be made therein without departing from the spirit and scope of the invention.