Abstract:
The present invention relates to automated guided vehicles, hereinafter referred to as AGVs, and specifically to AGVs used for entertainment purposes. More specifically, the present invention relates to a safety system for a passenger carrying AGV used for entertainment purposes. The present invention acts to prevent a passenger carrying automated guided vehicle from deviating from its intended path.

Description:
CLAIM OF PRIORITY 
     This application claims priority to foreign Application Serial No. GB 1309488.3, filed May 28, 2013, and also claims priority to foreign Application Serial No. GB1320389.8, filed Nov. 19, 2013, the entire disclosures of which are incorporated by reference herein. 
     BACKGROUND 
     The present invention relates to automated guided vehicles, hereinafter referred to as AGVs, and specifically to AGVs used for entertainment purposes. More specifically, the present invention relates to safety systems for a passenger carrying AGV, used for entertainment purposes. 
     Theme park rides typically utilise passenger carrying AGVs to provide an immersive entertainment experience. The AGV moves through a themed environment and its movement is synchronised with elements of the themed environment. Such elements may include, for example, scenery, props, animatronics, audio effects, visual effects, pyrotechnic effects and olfactory effects. So as to provide maximum passenger enjoyment, the movement of the AGV is synchronised very closely with the themed environment elements. As such, it is important that the AGV does not deviate from its intended path while moving through the themed environment. 
     So as to increase passenger enjoyment, there is a need from designers of immersive entertainment experiences to include more dynamic movement sequences of the AGV. For example, the AGV may be required to undergo periods of rapid acceleration and deceleration, to perform tight turns, to rotate on the spot, and to transition into reverse movement. Such movements may be undertaken in isolation or combination. The intention is to provide the passengers with an experience that they may perceive includes an element of danger, however it is imperative for passenger safety that all movements are conducted in a controlled manner. 
     SUMMARY OF THE INVENTION 
     According to a first aspect of the present invention there is provided a safety system for a passenger carrying automated guided vehicle used for entertainment purposes, the automated guided vehicle further being operable to follow a path defined by a radio signal broadcasting guidance wire embedded in a floor or surface over which the automated guided vehicle is intended to travel, the automated guided vehicle further being operable to execute one or more dynamic movement operations while following said path including, but not limited to lateral translation movements, spins, helical spins, slides in or contrary to the direction of movement of the vehicle, periods of rapid acceleration and deceleration or combinations of the foregoing, wherein the safety system includes a sensor operable to detect the radio signal broadcast by the guidance wire and a controller, wherein the controller has a first output which is generated when the sensor is able to detect the radio signal and a second output which is generated instead of the first output when the sensor is unable to detect the radio signal broadcast by the wire, wherein further the second output causes the automated guided vehicle to stop. 
     The present invention provides a safety system for a wire guided passenger carrying AGV which causes the AGV to stop in the event that it deviates from its intended path, for example during or after executing a dynamic movement operation. 
     The sensor of the safety system may comprise a ring antenna. In such an embodiment, the safety system ring antenna may be provided concentrically within a ring antenna used for guiding the automated guided vehicle along its intended path and/or synchronising movement of the automated guided vehicle with aspects of the environment through which is intended to travel. 
     Alternatively, the safety sensor may be provided on a rotatable body of the automated guided vehicle. In such an embodiment, it will be appreciated that by virtue of the rotatable body a ring antenna is not necessary. In such an embodiment the safety sensor may comprise a forward sensor element and a rearward sensor element. The rotatable body may further include an odometry sensor. A rotational position sensor may be associated with the rotatable body. 
     The automated guided vehicle may further include a peripheral sensor arrangement which is operable to determine if the periphery of the automated guided vehicle moves to a position outside of the normal operating parameters for the vehicle and thereafter cause the vehicle to stop. The peripheral sensor may comprise an antenna which extends around the periphery of the vehicle and which is operable to detect a radio signal broadcasting limit defining wire embedded in a floor or surface over which the automated guided vehicle is intended to travel, the peripheral sensor being operable to stop the operation of the vehicle in the event that the radio signal from the embedded limit defining wire is detected. 
     The peripheral sensor arrangement provides an additional layer of safety to the operation of a passenger carrying AGV in an entertainment environment. The peripheral sensor arrangement operates to stop the operation of the AGV in the event that a portion of the periphery of the AGV is positioned at or beyond a predetermined location during operation of the AGV even though the AGV may still be correctly located with reference to the guidance wire. The peripheral sensor arrangement may stop the operation of the AGV in the event that the AGV rotates beyond a predetermined location during or after a dynamic movement operation. 
     The safety system further includes first and second radio signal broadcasting limit defining wires embedded in a floor over which the automated guided vehicle is intended to travel, the limit defining wires being provided on opposing sides of the guidance wire. In various embodiments, at least one of the first and second limit defining wires may be spaced a constant distance from the guidance wire along the length of the guidance wire. In other embodiments, both the first and second limit defining wires may be spaced a constant distance from the guidance wire along the length of the guidance wire. 
     Alternatively, at least one of the first and second limit defining wires may be spaced at a varying distance from the guidance wire along the length of the guidance wire. In still other embodiments, both the first and second limit defining wires may be spaced a varying distance from the guidance wire along the length of the guidance wire. 
     According to a second aspect of the present invention there is provided a passenger carrying automated guided vehicle including the safety system described with reference to the first aspect. 
     According to a third aspect of the present invention there is provided a method for disabling the operation of a passenger carrying automated guided vehicle in the event that it deviates from an intended travel path. In various embodiments, the method comprises the steps of (1) providing a passenger carrying automated guided vehicle having a safety sensor and a safety controller, the safety sensor and safety controller being separate to guidance sensors and movement controllers of the vehicle, the automated guided vehicle further being operable to execute one or more dynamic movement operations while following said path including, but not limited to lateral translation movements, spins, helical spins, slides in or contrary to the direction of movement of the vehicle, periods of rapid acceleration and deceleration, and combinations of the foregoing, (2) providing a radio signal broadcasting guidance wire embedded in a surface over which the passenger carrying automated guided vehicle is intended to travel, (3) operating the passenger carrying automated guided vehicle so that it follows a path defined by the radio signal broadcasting wire, and (4) causing the safety controller to stop the vehicle in the event that the safety sensor is no longer able to detect the radio signal broadcast by the wire. 
     In various embodiments, the method may further comprise the step of providing peripheral sensor comprising an antenna which extends around the periphery of the vehicle and which is operable to detect a radio signal broadcasting limit defining wire embedded in a floor over which the automated guided vehicle is intended to travel, the peripheral sensor being operable to stop the operation of the vehicle in the event that the a radio signal from the embedded limit defining wire is detected. 
     According to a fourth aspect of the present invention there is provided a safety system for a passenger carrying automated guided vehicle used for entertainment purposes, the automated guided vehicle being operable to follow a path over a floor or surface which the automated guided vehicle is intended to travel, the automated guided vehicle further being operable to execute one or more dynamic movement operations while following said path including, but not limited to lateral translation movements, spins, helical spins, slides in or contrary to the direction of movement of the vehicle, periods of rapid acceleration and deceleration, and combinations of the foregoing, wherein the safety system includes a peripheral sensor comprising an antenna which extends around the periphery of the vehicle and which is operable to detect a radio signal broadcasting limit defining wire embedded in a floor over which the automated guided vehicle is intended to travel, the peripheral sensor being operable to stop the operation of the vehicle in the event that the a radio signal from the embedded limit defining wire is detected. 
     The peripheral sensor arrangement provides a safety system for the operation of a passenger carrying AGV in an entertainment environment. The peripheral sensor arrangement operates to stop the operation of the AGV in the event that a portion of the periphery of the AGV is placed at or beyond a predetermined location during operation of the AGV even though the AGV may still be correctly located on its intended travel path as determined by the AGV guidance system. The peripheral sensor arrangement may stop the operation of the AGV in the event that the AGV, for example, rotates beyond a predetermined location during or after a dynamic movement operation. 
     The safety system may further include first and second radio signal broadcasting limit defining wires embedded in a floor over which the automated guided vehicle is intended to travel, the limit defining wires being provided on opposing sides of the travel path. In various embodiments, the first and second limit defining wires may be spaced a constant distance from one another along the length of the travel path. Alternatively, in other embodiments, the first and second limit defining wires may be spaced at a varying distance from one another along the length of the travel path. 
     According to a fifth aspect of the present invention there is provided a passenger carrying automated guided vehicle including the safety system described with reference to the fourth aspect. 
     According to a sixth aspect of the present invention there is provided a method disabling the operation of a passenger carrying automated guided vehicle in the event that an edge of the vehicle deviates a predetermined distance from an intended travel path of the vehicle, the method comprising the steps of (1) providing a passenger carrying automated guided vehicle having a safety sensor and a safety controller, the safety sensor and safety controller being separate to guidance sensors and movement controllers of the vehicle, the automated guided vehicle further being operable to execute one or more dynamic movement operations while following said path including, but not limited to lateral translation movements, spins, helical spins, slides in or contrary to the direction of movement of the vehicle, periods of rapid acceleration and deceleration, and combinations of the forgoing, the safety sensor being a peripheral sensor comprising an antenna which extends around the periphery of the vehicle and which is operable to detect a radio signal broadcasting limit defining wire embedded in a floor over which the automated guided vehicle is intended to travel, (2) providing a radio signal broadcasting limit defining wire embedded in a surface over which the passenger carrying automated guided vehicle is intended to travel, (3) operating the passenger carrying automated guided vehicle so that it follows an intended travel path, and (4) causing the safety controller to stop the vehicle in the event that the peripheral sensor detects a radio signal broadcast by the limit defining wire. 
     In various embodiments, first and second limit defining wires may be provided on opposing sides of the intended travel path of the vehicle. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the present system will be described with reference to the accompanying drawings in which: 
         FIG. 1  shows a perspective view of a passenger carrying AGV; 
         FIG. 2  shows a schematic view of a path for such an AGV; 
         FIG. 3  shows a schematic top plan view of an AGV following the path of  FIG. 2 ; 
         FIG. 4  shows a schematic view of a guidance and safety arrangement for the AGV; 
         FIG. 5  shows a schematic top plan view of a steerable antenna array; 
         FIG. 6  shows a schematic top plan view of the steerable antenna array and an AGV; and 
         FIGS. 7 a  and 7 b    show schematic top plan views of an AGV having a peripheral safety antenna. 
     
    
    
     DETAILED DESCRIPTION 
     Referring firstly to  FIG. 1 , there is shown an automated guided vehicle, hereinafter referred to as an AGV, generally designated  10 . In the embodiment shown, the AGV includes a base  12 , an arm  14  and a passenger module  16 . The configuration of the AGV  10  is shown by way of example only and is not intended to be limiting. 
     The base  12  includes a number of drive units which enable the AGV  10  follow an intended path. In the embodiment shown the drive units are located in triangular projections  18  of the base  12 . The base  12  further includes a central pillar  20  to which a turntable  22  of the arm  14  is rotatably mounted. The arm  14  includes a lower arm portion  14   a  and an upper arm portion  14   b  which are pivotably connected to one another. The lower arm portion  14   a  is further pivotably connected to the turntable  22 . The pivotable connection between of the arm portions  14   a  and  14   b , and between the lower arm portion  14   a  and the turntable  22 , together with the rotatable connection of the arm  14  to the pillar  20  enables the arm  14  to move in a plurality of directions as indicated by arrows  24 ,  26  and  28 . 
     In the embodiment shown, the passenger module  16  is provided with a pair of seats  30  mounted in a side by side orientation. Each seat  30  is provided with a rigid harness  32  which ensures that an occupant  34  remains in the seat  30  when the passenger module  16  is moved by the arm  14  and further when the arm  14  and passenger module  16  are moved by the base  12 . The passenger module  16  is pivotably connected to the upper arm portion  14   b  and is movable relative to the arm  14  as indicated by arrow  36 . It will be appreciated that the passenger carrying arrangement of the AGV  10  described above is illustrative of one of many different passenger carrying arrangements that may be utilised by an AGV  10  used for entertainment purposes. For example, the seats  30  may be mounted to the base  12  of the AGV  10  and the arm  14  omitted. 
     Passenger carrying AGVs  10  of the type described above are typically used in a theme parks to provide passengers with an immersive entertainment experience. The AGVs typically move through a themed environment relating to, for example, a film or video game. The themed environment may include such elements as scenery, props, animatronics, audio effects, visual effects, pyrotechnic effects and olfactory effects. The aforementioned elements are provided by way of example only and are not intended to be limiting. As the AGV  10  moves through the themed environment its movement, as well as the movement of the arm  14  and passenger module  16 , is synchronised with the themed environment elements to provide the immersive entertainment experience. As will be described in greater detail below, it is very important that the AGV  10  does not deviate from an intended path through the themed environment. 
       FIG. 2  shows a schematic view of a travel path, generally designated  38  for the AGV  10 . The travel path  38  has a start point A and an end point B and extends in a sinuous manner between the start and endpoints A,B. In a typical themed environment the travel path  38  is in the form of a closed loop such that the AGVs circulate around the travel path  38 . The start point A may be defined by the passenger embarkation point of the path  38 , whereas the end point B may be defined by the passenger disembarkation point of the path  38 . The travel path  38  may be defined in the themed environment by a guidance wire which is embedded in the floor of the environment. A transmitter is connected to the wire such that a radio signal of a predetermined frequency is broadcast from the wire. The AGV  10  is provided with an appropriate sensor which is able to detect the radio signal. Markers are typically provided in the floor to assist the AGV  10  in determining its position on the travel path  38 . 
     Typically, the AGV  10  is configured to travel for the majority of the path  38  between start point A and end point B at a steady rate. At predetermined points along the travel path  38  the AGV  10  may undertake a dynamic movement operation. Such dynamic movement operations include, for example, lateral translation movements, spins, helical spins, slides in or contrary to the direction of movement of the vehicle, periods of rapid acceleration and deceleration, transitions into reverse, sharp turns or combinations of the foregoing. 
       FIGS. 3 and 4  show more detailed views of an AGV  10  and the travel path  38 . Looking firstly at  FIG. 3 , the wire defining a section of the travel path  38  is identified by reference number  40 . A plurality of markers indicated by references N and N+1 to N+7. The markers are positioned close to the wire  40  and, in the embodiment shown, are spaced at one meter intervals. The markers may be defined by RFD elements that are embedded in the floor of the themed environment. The AGV  10  is provided with a guidance sensor  42  which detects both the wire  38  and the RFID tags. 
     In use, the guidance sensor  42  determines that the AGV  10  is on the intended travel path  38  by sensing the radio signal emanating from the wire  40 . The guidance sensor  42  further determines the position of the AGV  10  along the travel path  38  by detecting the RFID tags. The guidance sensor  42  is connected to a movement controller (shown as item  44  in  FIG. 4 ) of the AGV  10  which, depending upon the location of the AGV  10  along the intended travel path  38 , causes the AGV base  12 , arm  14  and passenger module  16  to be moved in desired manner. In the embodiment shown, the sensor  42  takes the form of a ring antenna. 
     In order to provide the AGV passengers with the desired immersive entertainment experience the movement of the AGV base  12 , arm  14  and passenger module  16  are synchronised very closely with the aforementioned elements of the themed environment. It is thus of utmost importance that the AGV  10  does not deviate from its intended travel path  38  so as not to diminish the experience of the passengers or to potentially endanger the passengers by inadvertently contacting one or more elements of the themed environment. So as to ensure that the AGV  10  does not continue to act under the instruction of the movement controller  44  if the AGV deviates from the intended travel path  38 , the AGV  10  is provided with a safety sensor generally designated  46 . The safety sensor  46  takes the form of a ring antenna having a smaller diameter than that of the guidance sensor  42 . The safety sensor  46  is located within the space provided in the centre of the guidance sensor  42 . The guidance and safety sensors  42 , 46  are concentric. 
     The safety sensor  46  is connected to a safety controller  48  having two output channels  50 , 52 . The output channels comprise an OK channel  50  and an ERROR channel  52 . When the safety sensor  46  is able to detect the radio signal emanating from the wire  40  by virtue of being positioned over the wire  40 , the safety controller  48  provides an OK output to the OK channel  50 . This output enables the movement controller  44  to operate the AGV base  12 , arm  14  and passenger module  16  in the desired manner to synchronise with the themed environment. In the event that the safety sensor  46  is no longer able to detect the radio signal emanating from the wire  40 , then the safety controller  48  provides an ERROR output to the ERROR channel  52 . The ERROR output overrides the movement controller  44  and causes the AGV  10  to stop. Loss of the radio signal by the safety sensor  46  may be due to a number of factors including, for example, the AGV moving to a location where the safety sensor  46  is no longer positioned over the wire  40  or the wire  40  breaking. 
     Referring now to  FIG. 6  there is shown an alternative embodiment of an AGV, generally designated  54 , having a steerable guidance and safety antenna array, generally designated  56 . Features common to the embodiment described with reference to  FIGS. 1 to 4  are identified with like reference numerals. 
     As before, the AGV  54  is intended to follow a path  38  defined by an embedded wire  40 . The AGV  54  is provided with a plurality of combined drive and steering units  58 . Each unit  58  includes a ground engaging wheel  60 , a drive motor  62  and a steering actuator  64 . The drive motor  62  is operable to rotate the wheel  60  to effect movement of the AGV  54 . The steering actuator  64  is operable to pivot the wheel about a steering axis A-A so as to effect steering of the AGV  54 . In the embodiment shown, the AGV  54  is provided with four drive and steering units  58 . Each unit  58  is independently operable. As can be seen in  FIG. 6 , the drive and steering units  58  can be operated such that the front  66  of the AGV  54  can point in different direction to the direction of travel  68  of the AGV  54 . 
       FIG. 5  shows a steerable guidance and safety antenna array  56 . The array  56  includes a rotatable body  70 . In use, the rotatable body  70  is mounted for rotation in the AGV  54 . The array  56  is provided with a drive arrangement  72  operable to rotate the array  70  relative to the AGV  54 . The rotatable body  70  may be provided with a substantially circular periphery  76 . In such an embodiment, the drive arrangement  72  may be provided with a drive roller  78  which is in frictional engagement with the circular periphery  76 . The array  56  is further provided with an orientation sensor  80  which is operable to determine the rotational position of the array  56  relative to the AGV  54 . In the embodiment shown the orientation sensor  80  includes a roller  82 , in frictional engagement with the circular periphery  76 . 
     The rotatable body  70  includes an odometry sensor  84 . In the embodiment shown, the odometry sensor  84  includes a ground engaging wheel  86 . The rotatable body further includes a guidance sensor  42  and a safety sensor  46 . Instead of being concentric ring sensors, the guidance and safety sensors  42 , 46  each comprise a forward sensor  42   a , 46   a  and a rearward sensor  42   b , 46   b . The sensors  42   a , 42   b , 46   a , 46   b  are arranged on the rotatable body  70  in forward and rearward pairs such that the safety sensors  46   a , 46   b  are positioned closer to the rotational axis  88  of the rotatable body  70  than the guidance sensors  46   a , 46   b . This mirrors the arrangement of the concentric ring sensors described above wherein the safety sensor  46  is located within the space provided in the centre of the guidance sensor  42 . 
       FIGS. 7 a  and 7 b    show an AGV  54  including a peripheral safety antenna  90 . Features of the AGV  54  common to that described with reference to  FIGS. 5 and 6  are identified with like reference numerals. The safety antenna  90  of  FIGS. 7 a  and 7 b    may be used in conjunction with the safety sensor system of  FIGS. 1 to 4 . The safety antenna  90  is provided around the periphery of the AGV  54  and corresponds to the external shape of the AGV  54 . The surface over which the AGV  54  is intended to travel is provided with a guidance wire  40 . The surface is further provided with inner and outer safety or limit defining wires  92 , 94  provided on opposing sides of the guidance wire  40 . The safety wires  92 , 94  may be have a substantially constant spacing from the guidance wire along its length. Alternatively, one or both safety wires  92 ,  94  may have varying spacing from the guidance wire along its length. 
     During normal operation of the AGV  54 , the AGV is positioned such that the safety antenna  90  does not overlie either the inner or the outer safety wires  92 ,  94 . This is shown in  FIG. 7 a   . In the event that the AGV  54  rotates, for example during a dynamic movement operation, to such an extent that the antenna  90  overlies one or both of the safety wires  92 , 94 , then the antenna  90  will detect the or each wire  92 , 94 . In such an instance operation of the AGV may be halted to ensure the safety of the AGV passengers. 
     In an alternative embodiment, the safety antenna  90  is configured to detect the proximity of one or both safety wires  92 , 94 . 
     The safety wires  92 , 94  may extend fully along the intended path of the AGV  54  from its start point to its end point. Alternatively, safety wires may only be provided in the proximity of features of the themed environment through which the AGV  54  is intended to travel and which the AGV is to be prevented from contacting and/or approaching too closely. 
     The peripheral safety antenna  90  provides an additional safety system which operates, for example, in the event that the AGV  54  remains located on the guidance wire, but rotates beyond a predetermined limit as the result of undertaking a dynamic movement operation of the type described above. 
     In the above described embodiment, the safety wires  92 , 94  and safety antenna  90  are utilised in conjunction with an AGV guided by an embedded wire. It will however be appreciated that the safety wire and peripheral antenna arrangement  90 ,  92 ,  94  may be used in conjunction with AGVs having alternative guidance arrangements. For example, the AGV may be provided with an ultra-wideband radio ranging system which works in conjunction with inertial sensors. Alternatively, the AGV may for example be provided with magnetic or coloured guide tape navigation system, a laser guidance navigation system.