METHOD OF AND APPARATUS FOR GUIDANCE OF AUTOMATED VEHICLES

Abstract: The invention relates to a method of and an apparatus for guiding automated vehicles, particularly in a mine environment. The invention provides for an assembly for and method of providing a simulated towing action for automated vehicles. The assembly comprises a towing vehicle, an automated vehicle including drive means, steering actuation means and a controller connected to the drive and steering actuation means for control thereof, a tow frame towed behind the towing vehicle, and guiding means mounted on the tow frame and the automated vehicle for providing information to the controller of the relative spacing and orientation of the automated vehicle relative to the tow frame, whereby the controller controls the automated vehicle to cause the automated vehicle to follow the path travelled by the towing vehicle, and wherein the tow frame ensures adequate spacing between the towing vehicle and the automated vehicle. The invention also provides for a tow frame for use in an assembly comprising a towing vehicle and an automated vehicle intended to follow the towing vehicle in a manner of a simulated tow.

Description: Title: METHOD OF AND APPARATUS FOR GUIDANCE OF AUTOMATED VEHICLES FIELD OF THE INVENTION This invention relates to guidance systems for automated vehicles. More specifically, the invention relates to a method of and an apparatus for use in the guidance of automated vehicles in a mine environment. BACKGROUND OF THE INVENTION The use of automated or driverless vehicles is becoming more widespread. Such vehicles are commonly used in a variety of industrial settings, where it is desired to have one or more vehicles travel a set route, or in a defined network of routes. In such situations, automated vehicles offer considerable advantages and cost savings. Automated guidance systems for these vehicles have been developed for use in factories and the like. To keep the design of the guidance system simple and robust, a common element of most systems is to provide some clear indication of the path or route along which the vehicle is to travel. The route or routes are usually fixed or set, and it is simply a matter of making a single installation of some device marking the route. One known technique is to provide a wire or cable embedded onto the floor of a factory. A guidance system then uses the electromagnetic characteristics of this cable to guide the vehicle so that the vehicle follows the path of the cable. It is also known to use optical techniques and a strip painted on the floor. All of these systems have the advantage that the fixed element defining the intended path is simple, robust and passive, i.e. it does not require power nor is maintenance required for an active device. Automated vehicle guidance systems have also been developed for use in mines. A mining environment poses a wholly different set of problems from a conventional industrial setting. Firstly, the whole environment is much harsher than a conventional factory. Frequently, there are high levels of dust, and any path or route rather than being a smooth, concrete floor or the like may well be along the rough floor of a tunnel or drift. Further, the pathways of the vehicle in a mine are often irregular, both vertically and horizontally, and are subject to constant change. In a factory setting, the initial cost of the system defining the route or path of the vehicle is not usually critical, since it is a one-time cost. In a mine, on the other hand, where the route or path must be constantly changed and updated, the cost of installing devices or equipment to define the route is an extremely important factor. Additionally, in a mine, it may be difficult and costly to maintain a supply of electrical power throughout the mine. One example of a system used to guide automated vehicles in a mining environment is disclosed in Canadian Patent No. 2,041,073. The system provides a guide for a vehicle in the form of an elongate reflective strip suspended above the desired path for the vehicle. This provides a so- called coded longitudinal reference means, which more specifically is retroreflective. There are various proprietary tapes available which provide such retroreflective capability. The reflective strip would be detected by lasers. The lasers are oscillated from side to side, and the position of the laser is noted when a reflected beam is returned to the vehicle. As a further example, Canadian Patent No. 2,145,731 discloses an automated guidance system for a vehicle which provides a guide in the form of a continuous source of light arranged parallel to the intended path and above the vehicle. Such a source of light can be what is known as a "light rope". This is a commercially available product comprising numerous small bulbs encapsulated to form, in effect, a continuous rope or string. It provides a continuous, bright source of light, which is easily recognised by a vision guidance system. Some sort of vision guidance system is provided, so that an on-board vehicle guidance system can determine the lateral position of the vehicle relative to the "light rope", to guide the vehicle. Still further, pending United States Application No. 09/060,134, filed by the applicant, discloses a guidance system comprising a guide in the form of a fluorescent elongate element mounted along a desired path capable of absorbing radiation at a first frequency and radiating radiation at a different, lower frequency. The elongate element may comprise several portions which may be used to define different paths, each portion capable of radiating radiation at a frequency different from the radiation radiated by any other portion upon absorbing radiation of the first frequency. A portion of the elongate element is illuminated with radiation of the first frequency, and the radiated radiation is detected by a detector mounted on the vehicle. This provides positional information to the control unit, which can enable guidance means to steer the vehicle along the desired path. To date, the automation of mine vehicles in particular has been achieved by starting with a conventionally designed vehicle and adding to it the necessary automated control system. There are a number of reasons for this. Often, any automation scheme will only provide guide paths along high traffic routes, e.g. from a work face to a location for dumping ore. Consequently, there will always be occasions when a vehicle has to be manually driven, e.g. when it is to be taken to a service centre for routine maintenance. Additionally, many mine managers are reluctant to dispense with manual controls and rely solely on what may be perceived to be unproven automation technology. A further consideration is that automation equipment, with modern electronics, is relatively compact and lightweight, so that it is a simple matter to add this, in addition to standard manuai controls. Accordingly, many of the vehicles used today in conjunction with automated guidance systems such as those mentioned above are still built with manual control mechanisms (i.e., controls to be used by a human operator) despite the fact that the vehicles are used primarily in a mode where vehicle movement is automated and no on-vehicle manual control is required. The manual control mechanisms are thus used infrequently, typically only in situations where a vehicle is required to travel along a path where a guide is unavailable, and where it is either inconvenient, expensive, or otherwise undesirable to install a guide along the path. As noted, the manual control mechanisms may be used by an on-board driver to steer the vehicle to a garage or repair centre for maintenance or refuelling. The manual control mechanisms may also be used to move a vehicle from one set of paths where automated movement is possible, to a separate set of paths at a different location. Unfortunately, building or equipping automated vehicles with the capability of being operated manually can be costly. In particular, a mine environment can be very harsh, and providing suitable protection and at least some degree of comfort for the operator is costly. For example, it is common to provide special seats to prevent spine injuries, and the cost of the seat can be 15% of the total cost of the manual controls, which themselves can cost on the order of CAN $100,000. Thus, there is the possibility of substantial savings by building automated vehicles without manual controls. Accordingly, the present invention has realized that there is a need for a system and method to allow for automated vehicles not equipped with manual controls to move along on a path where the normal guide (e.g., reflective strip, light rope, or elongate element as described above) is unavailable. SUMMARY OF THE INVENTION One aspect of the invention relates to an assembly for providing a simulated towing action for automated vehicles comprising a towing vehicle, an automated vehicle including drive means, steering actuation means and a controller connected to the drive and steering actuation means for control thereof, a tow frame towed behind the towing vehicle, and guiding means mounted on the tow frame and the automated vehicle for providing information to the controller on the relative spacing and orientation of the automated vehicle relative to the tow frame, whereby the controller controls the automated vehicle to cause the automated vehicle to follow the path travelled by the towing vehicle, and wherein the tow frame ensures adequate spacing between the towing vehicle and the automated vehicle. The invention also provides for a tow frame for use in an assembly comprising a towing vehicle and an automated vehicle intended to follow the towing vehicle in a manner of a simulated tow. The tow frame comprises a tow frame, a coupling element at the forward end of the tow frame, at least two wheels supporting the tow frame, and signalling means for providing a signal to the automated vehicle enabling a controller on the automated vehicle to determine the relative position between the towing vehicle and the automated vehicle. The invention also provides for a method of providing simulated towing for an automated vehicle, the automated vehicle having drive means for driving the vehicle, steering actuation means for steering the vehicle and a controller connected to the drive means and the steering actuation means for the control thereof, comprising: (a) providing a towing vehicle and driving the towing vehicle over a desired path; (b) towing a tow frame behind the towing vehicle; and (c) providing on the towing frame and the automated vehicle guiding means, for providing an indication to the automated vehicle of the relative spacing between the automated and towing vehicles and relative orientation between the towing and automated vehicles, whereby the controller controls the automated vehicle to maintain a desired spacing at a desired orientation between the towing and automated vehicles. BRIEF DESCRIPTION OF THE DRAWING FIGURES For a better understanding of the present invention and to show more clearly how it may be carried into effect, reference will now be made by way of example, to the accompanying drawings, which show a preferred embodiment of the present invention and in which: Figure 1 is a perspective view of the present invention in a preferred embodiment; Figure 2 is a perspective view of a guiding tow bar mounted on a T-shaped tow frame; Figures 3a and 3b are perspective views of a guiding tow bar mounted on alternative tow frame designs; and Figures 4a, 4b and 4c illustrate the operation of signalling means on a tow frame in a variant embodiment of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to Figure 1 , a system for guiding automated vehicles 10 is shown. Preferably, system 10 operates to guide automated vehicles in a mining environment along paths which are not equipped with guides used for tracking by the automated vehicles. However, system 10 can operate on any path on which a vehicle can travel. System 10 comprises a towing vehicle 20, one or more tow frames 30, and an automated vehicle 40. System 10 may also comprise additional components to aid in the transport of automated vehicles 40 to a desired destination. The towing vehicle 20 is operated so as to lead an automated vehicle 40 to a desired destination. More specifically, the towing vehicle 20 is driven on a path to the desired destination while the automated vehicle 40 follows behind the towing vehicle 20. The towing vehicle 20 is preferably a jeep, but can be any manually-driven or automated vehicle including an automobile, a truck, a cart, a hauling vehicle, etc. In the preferred embodiment of the invention, the system 10 comprises at least one tow frame 30 which is hitched to or is otherwise pulled by the towing vehicle 20. Several tow frames 30 may be connected or hitched together in series, in known manner and as shown. The primary purpose of the tow frames 30 is to provide a safety zone between the towing vehicle 20 and the automated vehicle 40 following behind the towing vehicle 20. In the event that the automated vehicle 40 is unable to stop in sufficient time to prevent a collision with one or more tow frames 30 and the towing vehicle 20, the presence of the tow frames 30 makes damage to the towing vehicle 20 and injury to any occupants of the towing vehicle 20 less likely. In this context, a typical automated mining machine might be a Load Haul Dump (LHD) vehicle with a weight of, for example, 26,000 to 45,000 kilograms. Such vehicles are not very manoeuvrable and it is desirable to maintain a significant safety distance from a lightweight guidance vehicle. Note that simply setting a larger distance between the two vehicles is inadequate. In a mine environment, with narrow drifts, in order to ensure that the automated vehicle takes a proper path around corners, the vehicle must closely follow some guiding element. The tow frame 30 which is furthest away from towing vehicle 20 is equipped with a guiding tow bar 50. The guiding tow bar 50 comprises signalling means 52 which provide guiding elements and can be detected by one or more guide detectors 60 on the automated vehicle 40. For instance, the signalling means 52 can comprise radiation sources, where the radiated radiation can be detected by a guide detector 60. As a further example, guiding tow bar 50 may be equipped with a signalling means 52 which is a continuous source of light, where the light can be detected by the guide detector 60. Still further, guiding tow bar 50 may be equipped with a signalling means 52 comprising reflective or fluorescent means, which can be detected by the guide detector 60. Guiding tow bar 50 may also be equipped with signalling means 52 for emitting, for example, radio microwaves or other electromagnetic radiation, which can be detected by the guide detector 60. Guiding tow bar 50 may also be equipped with signalling means 52 capable of emitting a combination of the above signals. As noted, the automated vehicle 40 is equipped with the guide detector 60, and is also equipped with a controller 62 connected to the guide detector 60. The guide detector can be a camera looking axially or longitudinally; preferably there are two such cameras looking forwardly and rearwardly, for operation in either direction. Commonly such vehicles have two generally vertically directed cameras for following a light rope or the like and two cameras mounted for detecting falls. The controller 62 analyzes signals emitted by the signalling means 52 on the guiding tow bar 50 (for example, light, radiation, radio waves) and subsequently detected by the guide detector 60. The controller 62 uses this information to control the steering actuation means and the drive and transmission systems of the automated vehicle 40. The controller 62 determines from the signals detected by the guide detector 60 the relative longitudinal position of the guiding tow bar 50 with respect to the automated vehicle 40. This is done simply by determining the observed spacing of the signalling means 52 in the image taken by the camera 60. If the signalling means are too close together, indicative that the vehicles are too far apart, then the vehicle 40 is accelerated; if the signalling means or sources are observed to be too far apart, this is interpreted to mean that the vehicles are too close together and the vehicle 40 is slowed, either by simply decreasing power provided by the engine and/or by braking as required. Further, the positional information allows the controller 62 to steer left, right, or straight relative to the direction the automated vehicle 40 is currently moving, so that it follows essentially the same path traversed by the guiding tow bar 50. This is done by detecting the lateral location of the signalling means 52 in the field of view or image from the camera 60, and steering the vehicle 40, to keep the signalling means 52 centred. Therefore, as the tow frames 30 are attached to the towing vehicle 20, the automated vehicle 40 effectively follows the towing vehicle 20. This allows automated vehicles 40 to be moved without the need for on-board manual operation along paths for which guides are not installed. Hence, an automated vehicle 40 to be used in system 10 may be built without manual controls. In variant embodiments of the invention, the guiding tow bar 50 may be equipped with signalling means 52 which emits light or radiating radiation in pulses, at a specified frequency, to be detected by one or more guide detectors 60. This permits the controller 62 to distinguish between light being emitted or radiation being radiated by the signalling means 52 on guiding tow bar 50 from other sources of light (for example, natural light, headlights, flashlights, drift lighting, machinery equipment lights, or other reflective objects) that may interfere with the system 10 and cause the automated vehicle 40 to follow the wrong light or radiation source. In one embodiment of the invention, the signalling means 52 on the guiding tow bar 50 comprises two light or radiation sources separated at a specified distance on the guiding tow bar 50. As detailed, information relating to the distance separating the two sources can be used by the controller 62 in determining exactly how far automated vehicle 40 is from the guiding tow bar 50 at any particular time. The controller 62 is also able to stop or slow down the automated vehicle 40 (and to perform any other pre-determined desired actions) if the camera 60 fails to detect a signal (or fails to detect one of a number of detectable signals) from signalling means 52 after a specified period of time. For instance, if signalling means 52 is comprised of a light source, and the path from the light source to the camera 60 is interrupted (for example, if a person or vehicle crosses this path), the controller 62 may cause the automated vehicle 40 to stop. It is anticipated that there will be some form of communication between the automated vehicle 40 and the towing vehicle 20, if only to enable an emergency stop to be signalled to the automated vehicle 40. This communication link can also provide for the towing vehicle 20 to restart the automated vehicle 40. It can also enable the automated vehicle 40 to signal that it has lost contact with the signalling means 52, indicating that the towing vehicle 20 needs to back up. Also preferably, the towing vehicle 20 itself is equipped with means to stop or otherwise disable the automated vehicle 40, which may be useful if it is necessary to stop the automated vehicle quickly in an emergency situation. This can be implemented, for example, by connecting a radio receiver to controller 62 and providing a corresponding transmitter in the towing vehicle 20. Then, the receiver can cause the automated vehicle 40 to stop upon receiving a signal from the radio transmitter. In particular, the transmitter can include an emergency stop button, so that a driver of the towing vehicle 20 can signal the automated vehicle 40 to stop, for any desired reason. This radio transmitter can also be designed to maintain continuous communication (e.g. a signal indicating the status of the towing operation) with the controller 62. In the event that such radio communication is interrupted or becomes unavailable for a specified period of time, the controller 62 can cause the automated vehicle 40 to automatically stop. The radio transmitter and the radio receiver may also be adapted to communicate information regarding the distance between the towing vehicle 20 (or signalling means 52) and the automated vehicle 40. A display may be installed in the towing vehicle 20 which indicates the current distance between the two vehicles. In the event that the towing vehicle 20 is able to stop more quickly than the automated vehicle 40, the automated vehicle may tend to overshoot its desired position. For this situation, a low profile signalling means could be provided that enables the automated vehicle 40 to ride over the signalling means 52 without damaging it. Referring to Figure 2, details of the tow frame 30 having a T- shape are shown. A tow frame 30 comprises the guiding tow bar 50 and an elongate shaft 54. The forward end of the shaft 54 includes an aperture or coupling element 56 for coupling to a complementary coupling element. As shown, on an extension of the elongate shaft 54, there is such a complementary coupling element 58. Commonly, the coupling element 58 is some sort of a projecting ball or pin or the like, and the coupling element 56 is a corresponding socket. It will be understood that, for the rear most tow frame 30, the extension of the shaft 54 and the coupling element 58 can be eliminated. However, for convenience, it is preferable for the tow frames 30 to be similar. This enables any number of tow frames 30 to be coupled together, in any order, which can be useful for maintenance and other purposes. The signalling means 52 are mounted on top of the guiding tow bar 50 as shown. However, it is possible that the signalling means 52 be otherwise integral with the tow bar 50. Where the tow frame 30 omits the coupling element 58, the tow frame 30 must necessarily be the last tow frame. All intermediate tow frames 30 would need both coupling elements 56, 58. It will also be understood that the use of an intermediate tow frame 30 is optional. It is possible that just one tow frame 30 be provided, which need include just the coupling element 56 for attachment to the towing vehicle 20. Although the signalling means 52 are shown, schematically, mounted on the guiding tow bar 50, it will be understood that the signalling means 52 could be mounted as required for a particular installation. Thus, in some applications, it may be desirable to mount the signalling means 52 at the same height as a vision system on the automated vehicle 40. Additionally, the relative location of the signalling means 52 may depend on their nature. For example, as noted, the signalling means 52 can comprise a variety of radiation sources (e.g. conventional light sources, laser sources, radio sources), or can simply comprise some form of reflector. Preferably, the signalling means 52 mounted on the guiding tow bar 50 would be very low to the ground to enable the automated vehicle 40 to ride over it without damage, as detailed above. Reference can now be made to Figures 3a and 3b, which show two alternative embodiments of the tow frames designated as 80 and 90 respectively. Simplistic, like components are given the same reference numbers in Figures 3a and 3b, and the description of these components is not repeated. In Figure 3a, the tow frame 80 has a generally triangular shape and comprises elements 82 forming a triangular frame, with the guiding tow bar 50 forming or mounted on one end of the frame. Here, in addition to the two rear wheels 70, there is a single, front wheel 84 mounted as a cast wheel, so as to follow the direction determined by the vehicle 20. The wheel 84 is rotatively mounted in an inverted U-shaped frame 86, the U-shaped frame 86 being pivotedly mounted below a short elongate shaft 88 extending from the front of the triangular frame and on which the accompanying element 56 is mounted. Referring to Figure 3b, the tow frame 90 here includes a generally rectangular frame having side elements 92 and a front element 94. The rear element of the rectangular frame is again provided by the guiding tow bar 50. A short elongate shaft 96 is provided at the front, extending from the front element 94, and again providing the coupling element 56. In this embodiment of Figure 3b, the tow frame 90 now comprises rear wheels 70, and in addition, a pair of forward wheels 98 are provided. It will be understood that the wheels 98 are mounted for a steering action, so as again to permit the frame 90 to freely follow the path taken by the towing vehicle 20. It will be also understood that, in the tight confines of a mine, it is desirable that the guiding tow bar 50 closely follow the same path as the towing vehicle 20. Where conditions require the guiding tow bar 50 to be located some distance from the towing vehicle 20, and where the towing vehicle 20 has to traverse relatively tight turns, then, in known manner, the guiding tow bar 50 on the rearmost tow frame will tend to track radially inwards on turns. If this effect is significant, then the tow frames can be modified to allow for this. Thus, in known manner, a steering mechanism can be incorporated into the tow frames, to cause the wheels to steer, so as to cause each tow frame to accurately follow the path taken by the towing vehicle 20, without any tendency to track radially inwards. Such mechanisms are well known, and are commonly used, for example, in baggage carts and the like used at airports, where commonly a large number of baggage carts are towed as a train behind a vehicle, and for the same reasons as here, it is desirable that these baggage carts follow substantially the same path. Additionally, where tight turns are involved, this can impair the effect of the signalling means 52. In traversing a tight corner, the elements which comprise the signalling means 52 as viewed by a vision system on the automated vehicle 40, will appear to move closer together, since the vision system will be observing the tow bar 50 and the elements which comprise the signalling means 52 at an angle. The control system on the automated vehicle 40 should interpret this as meaning that the elements comprising the signalling means 52 have moved away from the automated vehicle 40, which will, erroneously, cause the automated vehicle 40 to accelerate towards the towing vehicle 20 and the guiding tow bar 50. Bearing in mind that the towing vehicle 20 may, when entering a turn, be decelerating anyway, this could have disastrous consequences, in that the automated vehicle 40 may overrun the rear left tow frame 30 at least. Again, to compensate for this, the signalling means 52 may be mounted on the frame element that is mounted for rotation on a vertical axis which is steered so as to always direct the signalling means 52 towards a location in which the automated vehicle 40 is anticipated to be. Bends and corners in the path may also prevent the automated vehicle 40 from successfully following the towing vehicle 20, if the camera 60 loses sight of the signalling means 52 as the towing vehicle 20 and rear tow frame 30 disappear around a bend or corner. A short stretch of conventional guidance light rope may be installed on the bend or the corner of the path to guide the automated vehicle 40 around the corner until the signalling means 52 is once again in view. The light rope would be visible to the camera 60. The controller 62 would automatically direct the automated vehicle 40 to follow the light rope if it loses sight of the signalling means 52, and would switch back to directing the automated vehicle 40 to follow the signalling means 52 once it is again in view. In Figures 3a and 3b, the additional coupling element 58 is provided. It will be appreciated that, for a tow frame 80, 90 including signalling means 52 which is always intended for use with the terminal or rearmost tow frame, then this coupling element 58 may not be provided. However, as mentioned, there are advantages in always providing it, to enable complete flexibility in the coupling of various tow frames. It will also be understood that for tow frames intended as intermediate tow frames, the coupling element 58 necessarily must be provided, but the signalling means 52 could be omitted, to simplify the tow frame and cheapen the costs of the tow frame. It will also be understood that while Figures 2, 3a and 3b show exemplary profiles of the tow frames, any geometric configuration is possible, and also any wheel arrangement is possible, which provides the necessary function. As noted, it is believed that for many applications, a camera on the vehicle may be used as the guide detector 60. The camera is connected to a controller 62 on the automated vehicle. The controller 62 is used during normal operation of the automated vehicle 40, for controlling and guiding the vehicle 40 along routes with guide elements extending along the routes. The controller 62 will have already been programmed, or should be programmed, to cause the automated vehicle 40 to follow the signalling means 52 in the manner described above, i.e. so as to maintain a specified constant spacing between the two signalling elements 52 and to maintain the signalling elements 52 in the centre of the field of view. It is also conceivable that, instead of using a separate camera for towing operations, the same camera used in other vehicle operations can be utilized. In particular, it may be possible to provide one camera for use in normal automated guidance where guide elements are provided, and for towing operations. For switching between the two modes of operation, it may be simply a matter of re-orienting the camera from a generally upwardly facing orientation to a generally horizontally directed orientation. Similarly, it is anticipated that it may be necessary to provide both forward and rearward facing cameras, if it is desired to have the automated vehicle 40 follow the towing vehicle 20 in either the forward or rearward direction. Again, this may prove unnecessary, at least for some vehicles; for example, it may be possible to have a single camera mounted, generally centrally on the vehicle, which can be switched between forward and rearward facing orientations. In variant embodiments of the invention, mirrors or other similar means may be used to "re-orient" the view of a camera without having to move the camera itself. In a variant embodiment of the invention, as shown in Figures 4a, 4b, and 4c, the signalling means 52 comprises a horizontal array of three lights 101 , 102, 103, with each pair of adjacent lights being separated by a specified distance, S. The lights 101 , 102, 103 are placed on the guiding tow bar 50 such that the centre light 102 is centred horizontally with respect to the back of the tow frame on which the guiding tow bar 50 is mounted. When a vehicle is being towed, the centre light 102 is permanently on. The outside lights 101, 103 alternate between being on and off, as shown in Figures 4a and 4b, at a rate between 5 Hz and 10 Hz for example. This variant embodiment anticipates providing a variety of unique identifiers embedded in the signals transmitted by signalling means 52. For example, where there are three lights 101 , 102, 103 comprising signalling means 52, the signalling means 52 can alternate between transmitting the signal pattern in Figure 4a ("A"), the signal pattern in Figure 4b ("B"), and a signal pattern ("C") as shown in Figure 4c to embed a unique identifier in the transmitted signals. Embedding the unique identifier in the transmitted signals requires the insertion of the signal pattern C at various times during the sequence of signal patterns A and B being transmitted. Such a unique identifier can be used to distinguish between different towing vehicles, so that any given automated vehicle can be controlled so as to only follow the tow frame having signalling means transmitting signals containing the unique identifier. Each signal pattern A, B, or C, is transmitted for a fixed duration. Suppose a synchronization string is defined as ABAB (where the letters refer to equal time period of the signal patterns A and B). A unique identifier is created by inserting signal pattern C in the signalling sequence such that the synchronization string never occurs in the middle of a code string. The light pattern must always change at a regular time interval. Here are some examples of unique patterns that could be used: ABABCABAB ABABCBABAB ABABCACABAB ABABCBCBABAB ABABCABACABAB ABABCBABCBABAB ABABCACBCABAB ABABCBCACBABAB ABABCACABACABAB ABABCBCBABCBABAB ABABCACBCACABAB ABABCBCACBCBABAB etc. As noted, in this example, ABAB represents the synchronization string. The coding is based on a simple binary tree. Variant embodiments of the invention may also include a remote control system for controlling the operation of the automated vehicle in a remotely-controlled mode. The remote control system can be used by an operator of a towing vehicle to initially line up the automated vehicle with the tow frame (on which the signalling means is mounted) being towed by the towing vehicle. The remote control system can also be used to start the engine of the automated vehicle. The remote control system is equipped with a device controlled by the operator of the towing vehicle, that can communicate with the controller of the automated vehicle to switch the operation mode of the automated vehicle from a remotely-controlled mode, to the towing mode. The controller of the automated vehicle (e.g. Strong Box® device) operates the front facing camera of the automated vehicle to search for the signalling means (or more specifically, the signalling means transmitting a sequence of signals with the desired unique identifier as determined by the operator through the remote control system, where applicable) in its field of view. If the signalling means is detected and the distance between the signalling means and the automated vehicle is separated by a pre-defined minimum distance (the distance being determined by the controller as measured by the apparent separation of the individual lights in the field of view), a "lock" light will illuminate on the remote control device controlled by the operator of the towing vehicle. The towing vehicle can move slowly away while the operator uses the remote control device to initiate forward motion of the automated vehicle, thus initiating a simulated tow. The automated vehicle begins to move forward following the towing vehicle. The controller steers the automated vehicle to keep the centre light (where there are three lights as in Figures 4a, 4b, and 4c) in the centre of the automated vehicle camera's field of view (adjusting for camera angle and offset), and continually calculates the distance between the automated vehicle and the tow frame equipped with the signalling means. If this distance falls outside a pre-defined maximum distance, the automated vehicle will stop, and the "lock" light on the remote control device will cease to illuminate. The "lock" light may be replaced with one or more lights designed to indicate the status or "health" of the towing operation. For example, in a normal towing operation which is being executed successfully, a status light can be illuminated in green to indicate this. Where the automated vehicle is not following the towing vehicle, the status light can be illuminated in red or can be off to indicate this. A variety of other colours or indicators may be used to indicate other situations, for example, when the automated vehicle is having difficulties following or keeping speed with the towing vehicle. The automated vehicle will stop if the controller loses radio contact with the remote control device. The remote control system may also comprise a means for the operator of the towing vehicle to stop the automated vehicle at any time. Thus, the automated vehicle will also be directed to stop if the operator has transmitted a "STOP" signal to the controller using the remote control device. The automated vehicle will also stop if the array of lights being followed are not detected for a pre-defined period of time. The controller may also be programmed to stop the vehicle if any other lights appear in the vicinity of the light array (e.g. brake lights). The remote control system may also comprise a display (e.g. a miniature television) which would allow an operator to view what is seen by the front facing camera on the automated vehicle. The remote control system may also comprise a display indicating the distance between the towing vehicle (or the signalling means) and the automated vehicle. The remote control system may also be adapted to communicate the speed of the towing vehicle to the controller of the automated vehicle to assist in the control of the operation of the automated vehicle. For example, if the towing vehicle's speed is zero, the automated vehicle may be directed to stop. At any time, the operator can terminate the towing mode and revert to a mode of remotely-controlled operation. It will also be well understood by those skilled in the art that, while a load haul dump vehicle has been shown, the invention has applicability to many different vehicles. For example, in a mining environment, it can also be applied to blasting machines and other vehicles. A load haul dump vehicle typically has a speed of 25 kilometres per hour and requires a 4 meter stopping distance. Accordingly, the tow frame 30 should be dimensioned so as to provide at least that distance and a suitable safety margin between the towing vehicle 20 and the towed vehicle 40. A typical LHD machine is a 26,000 to 45,000 kg machine, so that clearly a collision with the towing vehicle 20 of any force could, at a minimum, cause significant damage. It is also to be appreciated that, while the present invention has been described with signalling means on a tow frame or trailer and some sort of detector on the automated vehicle, other configurations are possible. Thus, these elements could be reversed, with a detector provided on the tow frame and some sort of signalling device on the vehicle. Whatever configurations are adopted, it may also be desirable to provide some sort of proximity detector mounted on the rearmost tow frame 30, as a safety feature. This proximity detector would continuously note the relative position of the automated vehicle 40, and if the automated vehicle 40 comes too. close to the tow frame 30, the proximity detector would automatically transmit a stop signal to the automated vehicle 40 and provide an indicator to the driver of the towing vehicle 20 of the situation and the transmission of the stop signal. Similarly, a single detection means 60 can be used both during normal operation of the automated vehicle 40 where the vehicle travels along paths following guides which are installed along the paths, and during towing operations where the automated vehicle 40 follows a towing vehicle 20. However, separate detection means may instead be used for the two operations, with both detection means connected to at least one controller on the automated vehicle 40. In a variant embodiment of the invention, the invention provides for a means to teach the controller of the automated vehicle about the path on which it travels and the desired velocity profile over that path while the automated machine is being towed. This would allow the controller of the automated vehicle to anticipate intersections and changes of direction, slope, tilt, etc. in the path, and to make adjustments to its speed and movement accordingly. In a variant embodiment of the invention, a light rope or a strip of material (e.g. plastic) embedded with a fluorescent or reflective substance may be attached to the back of a towing vehicle or a tow frame, and dragged behind the towing vehicle or the tow frame. Again, the tow frame could be provided with a low profile, to prevent damage should the automated vehicle accidentally ride over it. The light rope or strip could accordingly follow the path of the towing vehicle. An automated vehicle would detect the light rope or strip and follow the towing vehicle, maintaining the light rope or strip between the automated vehicle's wheels. The light rope or strip would be equipped with a desired point as well as position markings that would give an indication of the amount and direction of longitudinal deviation from the desired position (i.e. whether the machines were too close or too far apart). For instance, the light rope or strip could be equipped with light sources around a center white light region (indicative of a desired point where the automated vehicle 40 should be positioned), where the light sources could change to red if the automated vehicle was too close and to green if the automated vehicle was too far away, and where the light sources may also indicate when the towing vehicle is accelerating or decelerating. In variant embodiments of the invention, a physical bar may be connected to a tow frame in the event that the automated vehicle is an electric vehicle that requires power. The guiding tow bar can provide the automated vehicle through a connection on the physical bar with power to operate. Alternatively, a motor generator may be attached to an electric automated vehicle to provide the necessary power to allow the vehicle to follow the guiding tow bar. For example, the motor generator itself is often a vehicle of substantial size. In such a case, the motor generator vehicle could act as the towing vehicle and an electric cable would be provided between the two vehicles for transfer of electric power. The motor generator vehicle would then be equipped with signalling means in accordance with the present invention, to enable control of the two vehicles by one operator.

Claims: WE CLAIM: 1. An assembly for providing a simulated towing action for automated vehicles, the assembly comprising: (a) a towing vehicle; (b) an automated vehicle, the automated vehicle including drive means, steering actuation means and a controller connected to the drive and steering actuation means for control thereof; (c) a tow frame, towed behind the towing vehicle; (d) guiding means mounted on the tow frame and the automated vehicle, for providing information to the controller of the relative spacing and orientation of the automated vehicle relative to the tow frame, whereby the controller controls the automated vehicle to cause the automated vehicle to follow the path travelled by the towing vehicle, and wherein the tow frame ensures adequate spacing between the towing vehicle and the automated vehicle. 2. An assembly as claimed in claim 1 , wherein the guiding means comprises signalling means mounted on the tow frame and a detector mounted on the automated vehicle. 3. An assembly as claimed in claim 2, wherein the signalling means comprises at least two radiation sources mounted horizontally , spaced apart at the rear of the tow frame, and wherein the detector provides an image to the controller indicating the relative location of the radiation sources in the image, whereby the controller guides the vehicle to maintain the radiation sources centred in the image and at least substantially constant spacing, thereby to control the direction of the automated vehicle and the relative spacing of the automated vehicle from the towing vehicle. 4. An assembly as claimed in claim 1 , 2, or 3 which includes a variety of tow frames provided as trailers connected in series behind the towing vehicles, so as to provide adequate spacing between the towing vehicle and the automated vehicle. 5. An assembly as claimed in claim 4, which includes a transmitter mounted on the towing vehicle for transmitting a signal to the controller on the automated vehicle to stop the automated vehicle, and an actuation switch for the transmitter for an operator of the towing vehicle to stop the automated vehicle. 6. A tow frame, for use in an assembly comprising a towing vehicle and an automated vehicle intended to follow the towing vehicle in a manner of a simulated tow, the tow frame comprising a tow frame, a coupling element at the forward end of the tow frame for coupling complementary coupling element on the towing vehicle or another tow frame, at least two wheels supporting the tow frame, and signalling means for providing a signal to the automated vehicle, thereby to enable a controller on the automated vehicle to determine the relative position between the towing vehicle and the automated vehicle. 7. A tow frame as claimed in claim 6, wherein the tow frame comprises a rear guiding tow bar and an elongate shaft extending forwardly from the rear guiding tow bar, wherein the wheels are mounted at free ends of the rear guiding tow bar and the signalling means are mounted on the rear guiding tow bar. 8. A tow frame as claimed in claim 6, which includes one of a triangular frame and a rectangular frame, and at least one additional wheel for supporting the tow frame. 9. A tow frame as claimed in claim 6, 7 or 8, which includes steering means for steering the wheels of the tow frame, to cause the tow frame to follow closely a path travelled by the towing vehicle. 10. A method of providing simulated towing for an automated vehicle, the automated vehicle having drive means for driving the vehicle, steering actuation means for steering the vehicle and a controller connected to the drive means and the steering actuation means for the control thereof, the method comprising: (a) providing a towing vehicle and driving the towing vehicle over a desired path; (b) towing a tow frame behind the towing vehicle; (c) providing on the towing frame and the automated vehicle guiding means, for providing an indication to the automated vehicle of the relative spacing between the automated and towing vehicles and relative orientation between the towing and automated vehicles, whereby the controller controls the automated vehicle to maintain a desired spacing at a desired orientation between the towing and automated vehicles. 11. The method as claimed in claim 10, which includes providing signalling means on the towing frame and a detector on the automated vehicle for detecting radiation from the signalling means. 12. A method as claimed in claim 11, which includes providing at least two signalling means spaced apart on the towing frame, and, on the automated vehicle, detecting the perceived spacing between the signalling means as an indication of the spacing between the towing and automated vehicles, and the angular position of the signalling means, indicative of the angular orientation of the automated vehicle to the towing vehicle. 13. The method as claimed in claim 12, wherein the at least two signalling means are operated so as to uniquely identify the towing vehicle. 14. The assembly as claimed in claim 3, wherein the at least two signalling means are operated so as to uniquely identify the towing vehicle.

Inventors: POOLE ROSS A, PURCHASE F JACK, WARD ROBERT S, POOLE, ROSS, A., PURCHASE, F., JACK, WARD, ROBERT, S.
Applicants: AINSWORTH INC, POOLE ROSS A, PURCHASE F JACK, WARD ROBERT S, AINSWORTH, INC., POOLE, ROSS, A., PURCHASE, F., JACK, WARD, ROBERT, S.
Application year: 2001
Main classification: G05D1
IPC codes: G05D1