Abstract:
An automatic railless ground conveyor installation comprising a passive guide track determining the route network and individual driverless or unmanned traveling conveyor cars, each of which possesses a steering mechanism scanning in a contactless manner the guide track. The steering mechanism comprises a central scanning element which during straight ahead travel of the conveyor car is located over the guide track and after turning of the conveyor car onto the guide track serves to reset the steering deflection of the conveyor car and at least two scanning elements arranged to each side of the central scanning element at a progressively increasing distance therefrom. The outermost scanning elements when activated by the guide track serve to trigger a greater steering deflection than the inner situated scanning elements.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a divisional application of our commonly assigned, copending United States application Ser. No. 481,897, filed June 21, 1974, now U.S. Pat. No. 3,948,342. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to a new and improved construction of automatic railless ground conveyor installation of the type comprising a passive guide track which defines the route or stretch network and individual driverless or unmanned traveling conveyor cars or vehicles, each of which is equipped with a steering mechanism which scans in a contactless manner the guide track as well as a work control mechanism which contains a code reader in order to scan in a contactless manner individual code markings arranged at branches and identifying the same and directly influencing the steering mechanism in the sense of reaching a target or destination determined by a target code set at the work control mechanism. 
     Automatic trackless or railless ground conveyor installations of the previously mentioned type have become known to the art from the German Pat. No. 1,481,482, corresponding to U.S. Pat. No. 3,474,877. The conveyor cars of such ground conveyor installation are associated with the difficulty of exactly guiding such along the guide track since at the branching-off locations of the guide track, the so-called branches or junctions, the conveyor cars each carry out the same steering deflection irrespective of the deviation of the conveyor car from the guide track. This results in a certain compromise with regard to the magnitude of the steering deflection, with the result that the correction deflection is too great in those instances where there is a small branching-off from the guide track and too small in those instances where there is a more pronounced branching-off. As a result the conveyor car begins to oscillate. Moreover, the work control mechanism of such conveyor car is complicated since in the case of a branch-off location at a junction or branch which must be detected as a function of the target code the steering mechanism must deliver a command for achieving a positive steering deflection. 
     SUMMARY OF THE INVENTION 
     Hence, it is a primary object of the present invention to provide an improved construction of automatic railless ground conveyor installation of the previously mentioned type which is not associated with the aforementioned drawbacks and limitations of the prior art proposals. 
     A further object of the present invention aims at the provision of a steering mechanism for an automatic railless ground conveyor installation of the previously mentioned type, which notwithstanding its simple construction insures for a good guiding of the conveyor car along the track and permits simplification of the construction of the work control mechanism and the steering mechanism. 
     Now in order to implement these and still further objects of the invention, which will become more readily apparent as the description proceeds, the automatic railless ground conveyor installation of the invention is manifested by the features that the steering mechanism comprises a central scanning element which during straight ahead travel of the conveyor car is located over the guide track and after turning of the conveyor car onto the guide track serves to reset the steering deflection of the conveyor car. At least two scanning elements are arranged to both sides of the central scanning element at a progressively increasing distance therefrom and transversely with respect to the direction of travel. The outermost scanning elements when activated by the guide track serve to trigger a greater steering deflection than the inner situated scanning elements. 
     By virtue of the fact that the steering mechanism for scanning the guide track possesses, apart from a central scanning element, at both sides first scanning elements which bring about a smaller correction deflection, the conveyor car can be precisely corrected in the case of small deviations from the guide track. With greater deviations and particularly also in the case of branch-off locations the scanning elements arranged at a greater distance from the central scanning element become active and bring about a greater steering deflection which initially brings the conveyor car more rapidly into coincidence or alignment with the guide track. The remaining correction again can be performed by the first scanning elements situated closer to the central scanning element. 
     A particularly simple construction of the railless ground conveyor installation is realized when the steering mechanism possesses a cam switching mechanism operatively coupled with a steering drive and movable in proportion to the steering movement. Each scanning element has operatively associated therewith a cam disk cooperating with switching elements. Switching cam means of the central scanning element during its activation by the guide track and with turned steering closes a resetting current circuit for the steering motor and with the steering turned back interrupts the resetting current circuit. Switching cam means of the remaining scanning elements are arranged such that in order to limit the steering deflection they interrupt a drive current circuit of the steering motor. Instead of the cam switching mechanism for controlling the steering mechanism it would of course be possible to use other equipment structures such as an standard optical are angle measuring device. 
     A particularly advantageous construction of the steering mechanism is constituted by a so-called crank loop drive, wherein a crank pin thereof is located at the center of the loop during straight ahead travel of the conveyor car. Thus, with the same pivot angle of the crank pin the incipient steering deflections are smaller than those arising at a later period of time. In this way there can be realized a particularly sensitive steering of the conveyor car with small steering deflections. 
     An extremely preferred constructional manifestation of the invention is realized if the steering mechanism is directly coupled with the target code mechanism, so that in those instances where the conveyor car should not turn-off at the branch the outermost scanning element associated with the branch-off location is disconnected or rendered ineffectual. In other words, in the case of branching-off of the conveyor car at a branch which is determined by the target code mechanism the corresponding outermost scanning element detects the branch-off location and causes the steering mechanism to appropriately turn or deflect. Consequently, it is no longer necessary to impart to the steering mechanism as a function of the target code a positive steering pulse in the event that the conveyor car is to branch-off at a branch. This construction also renders to possible for the conveyor cars to travel over intersections, so that when it is not desired for the conveyor car to branch-off in the one or the other direction both outermost scanning elements can be disconnected. In the case where the conveyor car should branch-off in one direction it is only necessary to disconnect the oppositely situated outermost scanning element. In the case of a branch-off command the associated outermost scanning element takes precedence relative to the remaining scanning elements. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be better understood and objects other than those set forth above, will become apparent when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawings wherein: 
     FIG. 1 schematically illustrates in plan view a section of the stretch or route network of the ground conveyor installation of this development; 
     FIG. 2 illustrates in plan view of one of the conveyor cars with exposed drive- and control components; 
     FIG. 3 illustrates in side view part of the steering mechanism; 
     FIG. 4 is a plan view of the steering mechanism depicted in FIG. 3; 
     FIG. 5 is a block circuit diagram of the steering mechanism and the function or work control mechanism. 
     FIG. 6 illustrates a route branch or junction with a continuous branch code track and a marker; 
     FIG. 7 illustrates a branch or junction likewise with a continuous or uninterrupted branch code track and a forwardly located supplementary code track which extends parallel to the guide track; 
     FIG. 8 illustrates a branch with a branch code track formed by an interruption of the guide track; 
     FIG. 9 illustrates a branch according to the showing of FIG 8, however with a continuous or uninterrupted supplementary code track; and 
     FIG. 10 illustrates details of a length measuring device. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Describing now the drawings, in FIG. 1 there is illustrated a section of a route or stretch network at which a guide track A branches off at the junctions or branches B 1  and B 2  into guide tracks A 1  and A 2  constituting sidings or branched-off locations. The guide tracks are passive, i.e. they do not deliver any pulses. They can be, for instance, colored strips, bands or tapes formed of ferromagnetic material, metallic bands or tapes or so forth. In front of the route branches B 1  and B 2  there are arranged in each case the branch code tracks C 1  and C 2  constituting the branch codes, and which in the embodiment under discussion are themselves formed by the guide track. The length of the branch code tracks is determined by a supplementary code track D 1  located in front of the start of each of the branch code tracks C 1  and C 2 , such supplementary code tracks D 1  not only marking or designating the start of the branch code tracks C 1  and C 2 , but furthermore containing a supplementary code designated as &#34;branch&#34;. In front of such supplementary code track D 1 , and parallel to the guide track A, there can be arranged an auxiliary track E which alerts the code reading or reader mechanism to the fact that a supplementary code track must be scanned. This auxiliary track can also additionally trigger auxiliary functions in the conveying or conveyor cars. 
     At the siding or branch of the stretch formed by the guide track A 1  there is likewise arranged a supplementary code track D 2  which activates a story code mechanism which will be described more fully hereinafter in order to cause a subsequently connected transmitter to transmit a story code which should be received by a receiver 10 arranged at the stretch. The receiver 10 serves to recall and, if necessary, code a lift or elevator. 
     Traveling over the guide track is a schematically illustrated conveyor car 12 having a forwardly arranged and rearwardly arranged rapid stop feeler 14 for stopping the conveyor car when it strikes a hinderance or obstruction. The rapid stop feelers or high-speed stop feelers 14 are, for instance, hydraulically or pneumatically acting contact switches which are preferably constructed as hose loops. Furthermore, the conveyor car is equipped with forward and rearward situated scanning or feeler heads 22 serving to guide the conveyor car along the guide track A and for diverting such at the branches B 1  and B 2 . 
     Additionally, there is also illustrated a programming transmitter 18 which is arranged at the stretch or network, the construction and mode of operation of which will be discussed more fully hereinafter. 
     The conveyor car 12 which has been shown in FIG. 2 again has been illustrated to possess the high-speed operating stop feelers 14 at the front and rear end of such car. It also contains a steering or guide mechanism 20 embodying a feeler or scanner head 22, the steering drive or transmission 24, a steering motor 26 as well as a cam switching mechanism 28. Such steering mechanism is arranged at the front end of the conveyor car. Drive wheels 30 are actuated by the drive motors 32. The conveyor car also contains a work control mechanism 34. 
     FIGS. 3 and 4 illustrate details of the steering mechanism 20 portrayed in FIG. 2, of which there is arranged a unit at the front end of the conveyor car. The rapid stop feeler 14 and the scanning head 22 are arranged both at the front as well as also at the rear end, wherein however in each instance only the components located at the front in the direction of travel are activated. The conveyor or conveying cars therefore can travel both forwards and backwards. 
     The rapid stop mechanism is constructed such that it again positively places into operation the conveying cars, if desired with a certain time-delay, but in any event as soon as the obstruction or hinderance is removed. The rapid stop mechanism therefore not only functions as an emergency device but also as the active control element of the ground conveyor installation. The conveyor cars can travel without damage in an irregular sequence and can hit one another. The blocking stretches or paths required with the prior art ground conveyor installations are no longer necessary, since the rapid stopping mechanisms assume their function. 
     The steering mechanism 20 possesses the scanning or feeler head 22 which contains five scanning or feeler elements 36. A central scanning or feeler element 36 1 , which is located over the guide track A when traveling straight ahead, serves the purpose, after turning or deflecting the conveyor car onto the guide track, of bringing about resetting of the turning or steering deflection. Transversely with respect to the conveying direction and to both sides of the central scanning element 36 1  there are located at a slight spacing therefrom the first scanning elements 36 2 . Activation of the first scanning elements 36 2  brings about only a small steering deflection or turning effect and serves to correct the conveyor car during slight deviations from the guide track. At progressively larger spacing there are arranged towards the outside at both sides of the first scanning elements 36 2  the second scanning elements 36 3  which, during greater deviations of the conveyor car, especially when travelling in curves and at branches, come into play and bring about a greater steering deflection. The scanning elements 36 are operatively connected with the cam switching mechanism 28, wherein each scanning element has associated therewith a cam disk 38, the switching cams 40 of which cooperate with switching elements 2. The cam switching mechanism 28 is coupled through the intermediary of a toothed belt 44 with a steering drive 46 which is driven from a steering motor 48 likewise through the agency of a toothed belt 50. The steering drive or transmission contains a crank guide drive, the crank pin 52 of which, during the time that the steering roller 54 travels straight ahead, is located at the center of a loop 56. In order to permit a better null point correction in this instance the loop 56 is sub-divided into two halves, wherein in the one half of such loop the crank pin 52 engages during the movement towards the left and in the other half thereof there engages a crank pin during the movement towards the right. The arm 58 carrying the loop is connected with the steering roller 54. 
     During the straightahead movement of the conveyor car the switching cams 40 2  and 40 3  of the outer scanning elements 36 2  and 36 3  do not cooperate with the switching elements 42 2  and 42 3 , so that their contacts bear against the cam disks. Now if one of the outer scanning elements 36 2  or 36 3  is activated by the guide track A, then via the switching elements 42 2  or 42 3  and the corresponding cam disk 38 there is closed a current circuit which energizes the steering motor 48, so that a deflection or turning of the steering roller 54 occurs. The deflection continues for such time until the switching cams 40 of the corresponding scanning element 36 travel onto the associated switching element 42 and interrupt the current circuit, so that no further deflection or turning occurs. The conveyor car then travels back onto the guide track until the central scanning element 36 1  is energized by the guide track. Since the switching cam 40 1 , during a turning deflection, is not in engagement with the switch 42 1   it closes via the associated cam disk 38 a resetting current circuit which causes the steering motor 48 to rotate in the opposite direction, i.e. again sets straight the steering roller 54. The resetting of the roller occurs for such length of time until the switching cam 40 1  bears against the switching element 42 1  and interrupts the resetting current circuit. 
     In FIG. 5 there is illustrated the block circuit diagram of a conveyor car for the work mechanism 34 and the steering mechanism 20. The mode of operation of the steering mechanism 20 has been described in detail heretofore, so that at this point there is only additionally mentioned that the steering control 60 contains the cam switching mechanism 28. The work control mechanism contains two or three main groups, the target or destination code mechanism which is sub-divided into the branch code mechanism with the comparator 62 and the storage 64 and the story code mechanism with the storage 66 and the transmitter 68, and the supplementary code mechanism containing the storage 70, the comparator 72 and the command receiver 74 which is activated by a command transmitter 76 at the stretch or network. Common to all of the mechanisms is a proramming device or mechanism 78 which can be programmed either by a manual programming device 80 or by a programming receiver 82 which receives its signals from a programming transmitter 18. As the reading mechanism or reader of the work control mechanism there is used the central scanning element 36 1  of the steering mechanism, which is connected with a length measuring unit or device 84. Connected thereafter are the comparators 62 and 72 of the branch code mechanism and the supplementary code mechanism, respectively. The length measuring unit 84 is, for instance, constituted by a counting wheel which parallely travels with a drive wheel of the conveyor car and for each unit length delivers a certain number of pulses, as will be explained more fully hereinafter in conjunction with FIG. 10. The work control mechanism furthermore contains an auxiliary reading element 86 which responds to the auxiliary track E and is connected with the length measuring unit. 
     Further details of the construction and the mode of operation of the work control mechanism are as follows: It is possible to program the programming mechanism either by means of the manual programming mechanism or device 80 or preferably by means of the programming receiver 82 which is supplied by means of the programming transmitter 18, and which are preferably ultrasonic receivers and transmitters. They can operate for instance with four carrier frequencies and transmit binary coded signals. The programming device is for instance coupled by means of four respective lines or conductors with the storages 64, 70 and 66 of the branch code-, supplementary code- and story code-mechanisms. These storages are preferably constructed as flip-flop storages. With the four infeed lines it is possible to transmit up to sixteen commands. At a station, via the programming transmitter 18, ultrasonic signals are introduced in binary coded form to the programming receiver 82 and specifically, for instance, a target or destination code having three numbers between 1 and 10. After termination of such transmission the target code is transmitted to all three flip-flop storages. A fourth switching element subsequently renders the flip-flop storages 64 and 66 non-responsive to any further reception, whereas the flip-flop storage 70 of the supplementary code mechanism is capable of receiving further supplementary codes during the travel of the car and to transform such into appropriate commands. 
     If a thus programmed conveyor car travels along the stretch of FIG. 1, then the steering mechanism 20 scans with the aid of its scanning or feeler element 36 1  the guide track. If the auxiliary reading element 86 reaches the auxiliary track E, then, it delivers to the length measuring unit 84 a command that it must count upon arrival at the supplementary code track D 1 . If the central scanning element 36 1  reaches the supplementary code track D 1 , which is formed by omitting the guide track along a certain path, then the central scanning element 36 1  transmits a signal to the length measuring unit at which there is measured the length of the supplementary code track D 1 . The output of the length measuring unit is coupled with the comparator 72 of the supplementary code mechanism 70. The measured length of the supplementary code track D 1  must now coincide with the code stored in the supplementary code mechanism for the command branch or &#34;switch&#34;. Then the comparator generates an output signal which is further transmitted to the length measuring unit 84 and switches such to the comparator 62. During further travel of the conveyor car there now occurs a length measurement of the branch code C 1 . At the moment when the comparator 62 is connected with the length measuring unit 84, it delivers a signal to the length control which brings about that the outer scanning elements 36 3  are switched-off, i.e. they cannot recognize any branching or siding. The comparator 62 now continuously compares the length of the branch code track C 1  with the branch code which has been introduced. into the storage 64. If the branch code is shorter than the branch code track C 1  then the comparator again delivers an output signal which at the steering control 60 brings about an activation of the outer scanning elements 36 3 . During further travel of the conveyor car these outer scanning elements 36 3  can recognize or detect the siding or branch A 1  and the conveyor car turns off. On the other hand, if the branch code contained in the storage 64 is longer than the branch code track C 1 , then during the scanning of the branch code track C 1  there does not occur any activation of the outer scanning elements 36 3 , rather first at the end of the branch code track C 1 . In this position, however, the scanning head of the conveyor car is already past the siding or branch A 1 , so that the conveyor car continues to travel straight ahead and does not turn off. In this way there can be achieved the result that, for instance, with ten different length branch code tracks C there can be detected ten different junctions or branches. It should be apparent that there are not required any further active control elements along the stretch or network. 
     If the conveyor car travels along the branch or siding with the guide track A 1 , then it arrives at the supplementary code track D 2  which signifies &#34;Call Lift&#34;. The signal delivered by the central scanning element 36 1  at the length measuring unit 84 again arrives at the comparator 72 which compares the measured length with the supplementary codes of the storage 70. Consequently it determines that the supplementary code track D 2  intends to call the lift and transmits via its output connected with the transmitter 68 a signal for activating the transmitter. Such transmits the story code contained in the storage 66 to the receiver 10 arranged at the network, whereupon such calls and programs a lift or elevator. The lift basket can only possess a single guide track for the ascending as well as also for the descending direction of travel. 
     The supplementary code mechanism not only contains a comparator 72 connected with the length measuring unit 84, rather also a command receiver 74 which responds to a command transmitter 76 along the conveying path. By means of this command transmitter, which likewise can function with ultrasonic energy, it is possible to transmit different commands of the supplementary code mechanism. The comparator 72 and the command receiver 74 further possess different common outputs 88 which can be connected with different devices of the conveyor car in order to trigger appropriate functions. Thus, the supplementary code mechanism can serve the purpose of generating further travel signals, such as, start of the travel, turning, half-speed travel, opening or closing of the scanning elements, full speed travel, engaging or disengaging the coupling and the like. 
     In FIGS. 6 to 9 there are illustrated different variant constructions of the branch code track and the supplementary code track. 
     In FIG. 6 the branch code track C 3  again is constituted by a continuous i.e. non-interrupted line of the guide track A, the start of the branch code track C 3  being determined by a marker F. With this embodiment there is not present any supplementary code track in front of the start of the branch code track C 3 . 
     FIG. 7 likewise illustrates a continuous branch code track C 4  which is formed by the guide line A, and the start of which is determined by a supplementary code track D 3 . This supplementary code track is located parallel to the guide track A. 
     FIG. 8 illustrates a branch code track C 5  which is formed by an interruption of the guide line or track A along the length of the branch code track. 
     FIG. 9 corresponds to FIG. 8, however in this case there is located at the start of the branch code track C 5  a supplementary code track D 4  which is formed by a continuous line of the guide track A and the start of which is determined by a marker F. 
     FIG. 10 illustrates a possible arrangement of the length measuring device or unit wherein a disk 100 is located for example at the drive wheel 30 of the car 12. The disk 100 is provided along a circle with markings 101 having uniform spacing from one another. This spacing can correspond for instance to a length unit of the traveled path. These markings 101, which for instance can consist of metal strips, can be scanned by a scanning device 102 fixedly arranged at a frame of the car and which scanning device 102 then obviously would be part of the length measuring unit 84 of the block circuit diagram of FIG. 5. During rotation of the disk 100 the markings 101 move past the scanning device 102 as a function of the path through which the car has traveled. The scanning device 102 then can deliver a number of pulses corresponding to the rotation of the disk 100 and thus the length of travel of the car. 
     While there is shown and described present preferred embodiments of the invention, it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied and practiced within the scope of the following claims. Accordingly,