CA2305606A1 - Apparatus including two separate vehicles controlled to move at a predetermined relative position - Google Patents

Abstract

An apparatus includes a first self-propelled independently steerable vehicle having a control system operable by an operator on board the first vehicle which is arranged to carry out a first function at a first location. A second self-propelled independently steerable vehicle is arranged to carry out a second function at a second location spaced from the first location. The second vehicle is controlled automatically from the first to maintain an operator set working position along side the first vehicle. The set position can be changed to other working positions or to a safe position behind the first vehicle. The positions are determined by GPS or by ultrasonic distance measurement together with speed and inertia sensing devices to maintain the positions. The positions are adjustable. Examples disclosed include a marker for an agricultural implement, a loading truck for receiving discharge from a crop harvesting machine, and various echelon arrangements where the vehicles carry out the same function side by side such as road painting.

Description

APPARATUS INCLUDING TWO SEPARATE VEHICLES CONTROLLED TO
MOVE AT A PREDETERMINED RELATIVE POSITION
This invention relates to an apparatus including two separate vehicles where the relative position of the vehicles is determined and one vehicle is controlled relative to the other to maintain a predetermined positional relationship for carrying out in co-operation a predetermined task.
SUMMARY OF THE INVENTION
According to a first aspect of the invention there is provided an apparatus comprising:
a first self-propelled independently steerable vehicle having a control system operable by an operator on board the first vehicle for controlling operation of the first vehicle;
the first vehicle being arranged to carry out a first function at a first location;
a second self-propelled independently steerable vehicle;
the second vehicle being arranged to carry out a second function at a second location spaced from the first location;
and a control device for controlling operation of the second vehicle relative to the first vehicle so as to be maintained in convoy by the control device with the first vehicle at a predetermined position relative thereto.
Preferably the control device includes an input arrangement for operation by the operator on the first vehicle so as to change the position of the second vehicle relative to the first vehicle.

Preferably the input arrangement is arranged to provide at least one set position for the second vehicle relative to the first at which the second vehicle is maintained by the control device.
Preferably the input arrangement is arranged to allow the operator to adjust the set position.
Preferably the input arrangement is arranged to provide a plurality of set positions for the second vehicle relative to the first vehicle which can be selected by the operator at each of which, when selected, the second vehicle is maintained by the control device.
Preferably the input arrangement is arranged to allow the operator to override the automatic movement of the second vehicle as it moves from one set position to another with manual control in the event that the automatic movement meets some problems such as to steer around an obstacle.
According to one control arrangement, the control device includes a first GPS unit mounted on the first vehicle to provide a first output corresponding to the GPS satellite signals received by the first GPS unit, a second GPS unit mounted on the second vehicle to provide a second output corresponding to the GPS
satellite signals received by the second GPS unit, transmitters for transmitting the output data from each of the first and second GPS units to a computer, the computer being arranged to determine mathematically and repeatedly the positions of the first and second GPs units with respect to each other using the instantaneous GPS
outputs from each of the two GPS units and indicating an instantaneous position of the first vehicle as the first vehicle moves and control means for comparing the instantaneous position with the required position and for steering the second vehicle toward the required position in the event of a difference.
According to another control arrangement, the control device includes ultrasonic distance measuring elements for detecting a distance between the first and second vehicles.
Preferably the control device comprises: a first component mounted on the first vehicle and a second component mounted on the second vehicle; one of the components including a timing signal transmitter for transmitting timing signals to a receiver on the other component; one of the components including a first sound transmitter at a first location for transmitting first sounds at predetermined time intervals relative to the timing signals; and a second sound transmitter at a second location thereon spaced from the first for transmitting second sounds at predetermined time intervals relative to the timing signals; the other component having a sensor arranged to detect the first and second sounds; and a processor for determining from the time of detection of the first and second sounds relative to the timing signals distances of the second vehicle from the first and second locations so as to calculate the position of the second vehicle relative to the first vehicle.
Preferably the control device comprises: a first sensor system for mounting on the first vehicle for providing first outputs indicative of a direction and speed of movement thereof; a second sensor system on the second vehicle for providing second outputs indicative a direction and speed of movement thereof;
and a processor arranged to compare the first and second outputs in conjunction with said detected distance and to effect control of the vehicle in dependence thereon.

Preferably the control device is operable to provide instructions defining at least two positions of the second vehicle relative to the first vehicle, each position being located at a predetermined distance beyond a respective end of the first vehicle.
Preferably the control device is operable to provide instructions defining at least three positions of the second vehicle relative to the first vehicle, each of two of the positions being located at a predetermined distance beyond a respective end of the first vehicle and a third of the positions being a retracted safe position adjacent to the first vehicle.
Preferably the retracted safe position is substantially directly behind a central portion of the first vehicle.
Preferably the control device includes a manual override control for guiding the second vehicle around obstacles to its required position.
Preferably the second vehicle is controlled by wireless communication.
Preferably the second vehicle carries a sensing system for sensing an obstacle in its path.
Preferably the first and second vehicles are arranged in a first relative position to carry out the same function at transversely spaced positions and include a second safe position of the second vehicle behind the first vehicle.
The present invention can be used for various situations where two or more vehicles are controlled in convoy from a single operated vehicle. However a number of end uses are particularly important and provide a number of important features designed particularly for those end uses.

In one use of the apparatus, the first vehicle comprises a harvesting machine for harvesting an agricultural crop and wherein the second vehicle comprises a transport vehicle for carrying a load of the harvested crop and wherein the control device is arranged for the operator to control the position of the second 5 vehicle relative to the first so as to load the crop at a position on the second vehicle as controlled by the operator. The apparatus therefore provides, for example, automatic guidance of a grain truck while it is receiving a load of grain from a combine "on the go". Unloading on the go is a significant time-saving strategy at harvest, but full utlization of the capacity of the truck depends on proper distribution of the load of grain in the box, which in turn requires control of the position of the truck with respect to the un-loader stream during unloading. The apparatus therefore provides a kit of parts which can be installed on the combine and on the truck to take over control of the truck from its normal driver while it is running in the field along side the combine so that the combine operator can move the truck relative to its along side position to control proper deposit of the load. The apparatus thus automatically controls the direction and speed of the truck to maintain the alongside position but allows the operator to adjust the position.
In another use of the apparatus, the first vehicle includes an agricultural implement and wherein the second vehicle includes a ground marker for marking a required line of travel for the implement.
Preferably the ground marker device is arranged to generate a single line mark and the control device is arranged such that the single line is at a position spaced outwardly from an outer end of the implement.

In other agricultural uses, the guidance apparatus can be used to control a second device carrying out the same function at a transversely spaced position. Thus guidance can be provided of a second full size, but unmanned, field machine (seeder, sprayer, swather, combine, etc.) following a path as determined by a first, manually operated unit of the same type.
In military applications, one example is remote vehicle for mine clearing. A series of expendable, unmanned vehicles equipped with mine detection equipment could be used to follow the path of a single, manned vehicle to widen known safe routes through mine fields. Through subsequent passes of such an array of vehicles, entire mine fields could eventually be cleared. Another example is the automatic air-to-air refuelling of aircraft.
In the construction industry, further examples are: painting lines on highways using a single pass of a master vehicle and subsidiary vehicles as opposed to multiple passes with a single paint truck as is now done; operation of multiple land packers in convoy, as for road construction. The convoy can be configured in a lateral spread for the packing pass, then configured into a long train (in a safe position as set forth above) to turn around.
In one primary example, field markers are a well-known and popular means of ensuring orderly and efficient field coverage during many spatially progressive agricultural operations. Generally, all such markers function by creating a temporary demarcation at the edge of, or laterally offset by a fixed distance from, the previous path of the implement, so that the operator can use the demarcation as a visual gauge for guiding the machine on the subsequent pass. The mark may consist of a distinct soil disturbance such as the furrow created by an angled or concave rolling disk or the scrape mark created by a length of heavy chain, or it may involve the deposition of a conspicuous substance or object such as a "blob"
of high-durability foam, a paper streamer, or a paint mark. Where it is mentioned herein that the field is marked, this does not necessarily require that the marking is effected by a mark on the ground but other marking techniques can be used.
Use of markers is necessary because the efficiency of most field operations is greatly affected by path errors, which result in overlap or "skipping". In some cases, such as when applying herbicide with a sprayer, there is almost no visible evidence of the machine's previous path, and a marker of some kind is absolutely required in order to determine a path that is even roughly parallel to the last. Even a mark to delineate the edge of the previous implement path provides a great benefit in such a case. In other cases, such as when seeding, the previous path of the implement may be readily apparent to the operator, and in the absence of any other path indicator or mark, the operator can determine a reasonable path by visually estimating the relative lateral offset between some part of the tractor-implement system and the edge of the previous implement swath. In both of these cases, though, the operator will normally try to err on the side of safety by intentionally selecting a path that results in some small amount of overlap.
This situation may be improved greatly by the creation and use of a mark that is offset from the previous implement path and indicates the desired path of the tractor rather than the implement. The amount of path error associated with such a marking method is very small, and represents a meaningful cost saving.
For instance, it has been shown that an investment of $7000 in a set of markers used only for seeding can provide full payback in as short as 1 year.
Of the mechanical markers currently available for creating this preferred offset mark, virtually all are of the hydraulically deployed, mounted type, and are well suited to only a few limited applications. Specifically, mounted, folding markers work well with smaller (3-section) tool frames, such as are used for air drills, planters, and the like, but these markers work less than satisfactorily with large (5-section) tool frames, and cannot be applied at all to sprayers, where perhaps their greatest benefit might be realised. Marking for sprayers is currently limited to the demarcation of the edge of the previous pass because the weight of these folding marker arms cannot be supported at the end of a relatively lightly built spray boom.
There are a number of North American manufacturers attempting to develop and market field guidance systems based on the Global Positioning System (GPS). Generally, these systems use a computer processor to interpret the "ideal"
path for the tractor and implement based on the previous recorded path, and then attempt to guide the operator to steer the tractor onto this ideal path using a visual display. Such systems have many inherent problems, and early market offerings have been poorly received. Some of the systems currently available cost over $25,000, and while the location determined through differentially-corrected GPS has the "potential" to be accurate within a few centimetres, in practice this is rarely the case. Accuracy of about half a meter seems to be achievable for at least some of the time, but this is only a small improvement over the visual method using a demarcation at the edge of the previous pass. Furthermore, all current GPS
based systems require the operator to reference some kind of electronic visual display such as a light bar or computer screen. Using this kind of artificial cue for steering is counterintuitive, and most operators find it difficult and tiresome to use.
There is considerable scepticism that GPS-based guidance can ever provide acceptable performance and reliability for agricultural applications at a realistic cost.
In light of the foregoing, a completely different approach to field marking is required to overcome the limitations of current products. The new concept is generally for a small self-propelled vehicle that incorporates a means for producing a physical mark in the soil, and that uses an electronic control system to follow any implement at a measured offset distance such that the mark produced defines the subsequent path to be taken by the tractor. This concept utilizes the tried-and-true soil demarcation method that has been used by mechanical markers for many years, without any of the inherent problems associated with supporting the weight of a complex support and folding apparatus at the end of wider implements.
Moreover, the device is easily adapted from one implement to another, so that when performing a sequence of operations such as seeding and spraying, the device can be used with each of the different implements, thus multiplying the benefits of its use with virtually no additional capital investment.
The concept is a significant improvement over the current state of the art because:
a) the implement is unaffected by the load of a heavy attached device b) the marker is easily moved between implements for different operations c) the mark produced allows the operator to look straight ahead and out the windows of the cab, regardless of the implement with which it is used.
5 d) the system has the inherent accuracy of a mechanical marker, even though it is electronically based.
It is a further aspect of the present invention to provide a control system which can be used with existing vehicles to effect control of the second vehicle as set out herein Embodiments of the invention will now be described in conjunction with the accompanying drawings in which:
Figure 1 is a plan view of an agricultural implement and ground marker arrangement according to the present invention.
Figure 2 is a schematic enlarged view of one embodiment of the marker vehicle of Figure 1.
Figure 3 is a schematic illustration of a first type of control unit for use with the vehicle of Figure 2 to be mounted on the implement for control by the operator.
Figure 4 is a schematic illustration of a second type of control unit to be mounted on the implement for control by the operator.
Figure 5 is a schematic enlarged view of a second embodiment of the marker vehicle of Figure 1 for use with the control unit of Figure 4.

Figure 6 is a plan view of a second example of an apparatus according to the present invention in which two vehicles each carrying out the same function are arranged to move simultaneously across an area to be acted upon.
Figure 7 is a plan view of a third example of an apparatus according to the present invention in which a first vehicles in the form of a crop harvesting machine is controlled by an operator to move alongside a second vehicle in the form of a load carrying vehicle for loading with the crop material from the first vehicle.
DETAILED DESCRIPTION
In the first embodiment shown in Figures 1 to 6 there is shown a conventional farm implement is shown in Figure 1 which can be of any type which is transported across the field to form a swath of activity across the field between side edges 11 and 12 of the implement 10. The implement is shown as a towed device but self-propelled implements can also use the marker system and control system set forth hereinafter. In the embodiment therefore there is shown a tractor 13 with an operator station 14 including a control unit 15 for the marking system.
In this arrangement the marker is provided as a self-propelled vehicle 16 shown in more detail in Figure 2 which can be moved between three separate set positions 16A, 16B and 16C relative to the implement.
The vehicle 16 comprises a frame 17 mounted on ground wheels 18.
In the embodiment illustrated the vehicle is of the skid-steer type in which all four wheels are driven but the wheels on the right hand side are driven through a motor 19 and chain drive 20 so that those wheels are driven at the same speed and in a selected direction and the wheels on the other side are driven by a motor 21 through a chain drive 22 so that those wheels can be driven at a selected speed and in a selected direction different from that of the first set of wheels. In this way the vehicle is steered by a difference in the speed of the wheels and can be rotated about its vertical center line by driving one set of wheels forward and the other set in reverse.
Such vehicles have therefore considerable manoeuvrability.
However other types of vehicle can be used including for example a conventional ATV such as a four wheel cycle which is modified by the provision of an electronic control package as described hereinafter. The vehicle includes a central processor unit 22 which controls the motors 19 and 21. The central processor unit receives information from a digital radio receiver 23 and from a GPS
receiver system 25.
The vehicle further includes a marker 9 for forming a mark on the ground. In the embodiment shown the marker comprises a disk 8 carried on an arm 7 at a rear of the vehicle so as the vehicle moves forwardly the disk forms a furrow 6 in the ground. Alternative known arrangements of marker can be used in replacement for the conventional disk.
In Figure 3 is shown one sensing and control system 15 for mounting on the implement at the operator station. This comprises a manual control unit having a joystick control 31 with a manual override switch 32 operable for taking over manual control of the marker vehicle as described hereinafter. The manual control unit 30 further includes three switches 33, 34 and 35 which allow the operator to select one of the three required positions 16A, 16B and 16C
respectively.
The control unit 15 further includes a central processor 36 and a transmitter 37 for transmitting information by digital radio transmission from the control unit 15 to the radio receiver 23 of the vehicle.
In Figure 3 the system operates by GPS so the system includes a GPS
receiver 38.
An alternative arrangement is shown in Figures 4 and 5 which includes the manual control unit 30, the processor 36, the transmitter 37. However in this arrangement instead of the GPS positioning there is provided an ultrasonic transmitter # 1 indicated at 40, an ultrasonic transmitter #2 indicated at 41 and a timing pulse transmitter 40A. In this arrangement the transmitters #1 and #2 are located at different positions on the implement preferably on the center line of the vehicle for symmetry as shown at 40 and 41 in Figure 1.
In this arrangement using the ultrasonic location system of Figure 4, the vehicle includes an ultrasonic sensor receiver 24A and a pulse sensor 24B
as described hereinafter.
The system of Figures 4 and 5 further includes additional sensors for assisting in the automatic control of the vehicle and these include a first inertial sensor 45 mounted on the implement and a second inertial sensor 46 mounted on the vehicle.
The timing pulse transmitter can be mounted on either of the vehicles with the corresponding receiver on the other. Also the sound transmitters may be mounted on either vehicle. There is an advantage although not essential that the pulse transmitter is on one and the sound transmitters on the other.
The marking element as shown comprises a rolling disk, mounted to the chassis of a small, self-contained and highly mobile vehicle. The specific vehicle configuration can vary, but generally speaking, the vehicle includes a small power source 50, a continuously-variable transmission such as a hydrostatic or variable-ratio belt drive, a steering mechanism (conceivably implemented with two transmissions in a "twin path" arrangement), and some "all-terrain" traction element.
The steering and transmission is directly controlled electronically, and so will require some type of actuator or servo interface.
In some field situations, such as when using a high clearance sprayer in advanced cereal crops, it is possible that the soil furrow type of mark would be obscured by the crop. In this specific application, a modified version of the marker vehicle could be specified, with appropriate high-clearance capabilities and an alternate marking means, such as foam blobs.
In general, the system of electronic sensors performs a relative position measurement between the marker and the implement. Two ways to accomplish this are shown, and either method can be used depending on factors of performance and cost. Selecting one method over the other does not affect the fundamental concept of the device. In both cases, the sensor system includes components on the marker vehicle as well as on the implement as set forth above.
This system shown in Figures 4 and 5 incorporates a series of transducers and sensors installed on the implement itself, as well as on the vehicle.
The sensors produce two redundant signals, to be used as most appropriate. One signal corresponding to relative direction and speed is derived by sensors responsive to direction and speed. The direction and speed of each vehicle can be derived from a ground speed indicator and/or from one or more inertial gyros on the respective vehicle and control is effected by comparison of the output from the inertial gyros indicated schematically at 45 and 46, one mounted on the implement and the other on the marker vehicle. Another signal indicating actual relative 5 position is produced by direct ultrasonic measurement of the location of the vehicle with respect to the implement. This measurement is accomplished by the sequenced broadcast of ultrasonic pulses from two or more locations on the implement. The time at which the pulses are broadcast from each location 40, 41 is precisely controlled, and the arrival time of each of the pulses at the marker location 10 will thus define the geometric position of the marker with respect to the implement (Figure 4). Prior to each sequence of ultrasonic pulses, a synchronization pulse is sent by radio from the transmitter 40A of the implement to the receiver 24B of the marker vehicle to ensure that the time of flight of the ultrasonic pulses is accurately measured.

15 The ultrasonic system preferably includes more than two ultrasonic transmitters and preferably a plurality of groups of two transmitters, each group arranged at a respective set position of the second vehicle. Each group of transmitters being used at any one time depending upon the position of the second vehicle transmits in a predetermined and controlled sequence with respect to the transmission of the initial timing (radio) signal. This is because the transmitters are somewhat directional, and thus it is in some cases necessary to set up a series of transmitters pointing to the left when the marker is to run to the left, pointing to the rear when the marker is to be running to the rear, and pointing to the right when the marker is to be running to the right. The left, rear, and right pointing transmitters may be located at exactly the same places on the implement frame. The ultrasonic pulses transmitted from each of the different transmitters are preferably modulated such that the signals are distinctly different from each other, allowing the specific source of each ultrasonic pulse to be identified when it is received by the receiver.
This is to resolve possible ambiguities with respect to the distance calculations An alternate means of relative position measurement involves the use of two inexpensive GPS receivers 38, 24, one located on the implement and the other located on the marker. The position data generated by the two receivers is compared in real-time, producing a very accurate measurement of relative position.
This is fundamentally different from the way GPS is most commonly used now, and overcomes completely the accuracy limitations of GPS.
In many common GPS applications, including the attempts to date to use GPS for agricultural machinery guidance, various secondary systems and methods are used to correct the error component that is intentionally incorporated into the GPS signal. This is called differential correction, and involves the establishment of one or more fixed reference sites in the general locale of interest, at which the GPS error is measured and then transmitted, either directly or via satellite, to a differential receiver co-located with the mobile GPS receiver. Such systems are intended to provide an absolute position measurement, and they generally accomplish this with reasonable accuracy, although as already discussed, they do not consistently provide the degree of accuracy required for field guidance.
This is partly due to the difference in location between the mobile GPS receiver and the differential site; if the two are located within even a few miles of each other, then they will generally receive the same signals from the same GPS satellites, but as the distance between the differential receiver and the mobile receiver increases, they "see" different groups of satellites, and so are subject to slightly different errors.
These problems could be overcome if users established their own local differential sites, but most seem reluctant to make this kind of commitment to a new technology, and it has not generally been done. Even if local differential sites became common, the currently offered guidance systems still force the operator to refer to an artificial indicator of some kind, which is not practical nor likely to be widely accepted.
Thus a first GPS unit mounted on the implement is arranged to provide a first output corresponding to the raw GPS satellite signals received by the first GPS unit. A second GPS unit mounted on the marker is arranged also to provide a second output corresponding to the raw GPS satellite signals received by the second GPS unit. There are provided one or more transmitters for transmitting the output data from each of the GPS units to a single computer and appropriate software running on the computer which operates to carry out the same calculation on the two separate signals to determine mathematically and repeatedly the relative positions of the two GPs units with respect to each other using the instantaneous GPS data from each of the two GPS units. The use of the same algorithm in the same computer at the same time to calculate from the raw signals avoids any discrepancies which can occur if the signals are interpreted by different computers.
The system cannot therefore utilize two separate commercially available GPS
systems one on each vehicle but instead must use a dedicated computer arranged to receive the signals from both vehicles.
Both receivers are always, by definition, located within 100 feet or less of each other, and so would receive substantially identical GPS signals, and be subject to exactly the same positional error. This means that comparison of the positions of the two GPS receivers as calculated from the raw GPS signals received at each location respectively can provide a highly accurate measurement of the relative positions of the two receivers, even if the calculated positions are not absolutely accurate with respect to external geographic references.
At issue is the fact that both receivers will generally see signals from more satellites than are strictly necessary to make a position calculation, and so position calculations "normally" made by standalone receivers are made several times using different combinations of satellites, and then of all these "possible"
answers, another set of calculations are performed to determine what the "real"
position most likely is. In the second calculation, some of the "possible"
positions are given greater or lesser weighting, depending on the quality of signal detected from the satellites used to make that particular position calculation at that particular instant. This is one of the ways in which two receivers located closely together will differ, because the variables that affect the quality of the satellite signals and thus the solution weightings and final "most likely position" calculation can be very different between the two locations, like satellite signal reflections off of nearby objects or the orientation of the receiver antennae. Also, it is not possible to simply subtract one GPS position from the other and cancel the errors because these errors vary continually, and unless the two GPS receivers are somehow synchronized to make their position readings at the exact same instant, then there will be a phase difference in the calculations are not accounted for. (The error we are trying to "cancel" could vary significantly in a 10th of a second, and if we only take a reading every second from each receiver, then we have no way to know precisely when each calculation was made, other than sometime in the previous second, which isn't good enough.) This is why the present arrangement takes the raw satellite signals from each receiver and gets them together on one computer before doing any position calculations: The system then be sure that all the redundant calculations of the simultaneous geometric solutions are weighted equally between the two locations, and we can also time-align the data from the two sources before each calculation.
The control system consists of an electronic micro-controller 22, along with supporting circuitry, located on-board the marker vehicle, and a similar micro-controller 36 on the implement. A radio modem 37, 23 connected to each micro-controller transmits operator commands from the cab and positional data from the implement mounted GPS receiver and/or inertial data from the implement gyro to the marker. Software implemented on the two micro-controllers acts to acquire and interpret the signals from the various components of the sensor system, accept the commands provided by the operator, and transmit the data between the two micro-controllers. Position measurements and data transmissions can be made several times each second.
Relevant safety issues associated with the function of a "driverless"
vehicle include:

a) limiting the travel of the marker vehicle to the boundaries of the particular field in which it is operating using the same GPS signal utilised for the precision guidance function.
b) incorporating a manual override mode 31, 32 into the controller, 5 so that in the event of a malfunction, the operator assumes direct control of the unit with a "joystick" type control as used with radio-controlled toys.
c) continual monitoring of the radio modem link, so that in the event of a control link failure, due either to component malfunction or the marker travelling out of radio range of the implement, the unit is automatically stopped rather 10 than allowed to travel uncontrolled into other fields or across roads.
d) inclusion of an on board sensor 25 to detect objects or people in the path of the vehicle. In the event of detection, the operator is given a warning signal allowing him to take over operation of the vehicle until it can be released from direct control to be allowed to move under its own control to the selected one of the 15 three positions.
The micro-controller on the marker vehicle is programmed to convert the sensor data and operator commands into vehicle commands, using standard digital control methods. The marker vehicle is thus guided to maintain a constant, laterally offset station with respect to the implement. The mark so produced will 20 align with the required centre-line of the tractor on the subsequent pass, so that the operator merely has to align the hood ornament on the tractor with the mark.
This is a natural and intuitive cue for the operator to use.
The operator controls the system using the small push-button control box or panel 30 located in an appropriate position at the operator's station.
This operator interface is identical to one already used for an automatic marker controller shown and described in US Patent 5,833,010 of Scott and Sjoberg, the disclosure of which is incorporated herein by reference.
Thus most of the control actions required to operate the system are already familiar to many operators, and most will be able to use the new marker system immediately without additional training or adjustment of operator patterns.
The control box allows the operator to select which side of the implement is to be marked at positions 16B or 16C, or alternately to send the marker vehicle to the "safe" or "follow" station 16A immediately behind the implement.
The marker system is able to determine its position and receive communications as necessary from the implement-mounted components to a distance of at least 120 feet. Marking accuracy is within 10 cm.
The mobility performance requirements of the vehicle system are directly dictated by the application, and by geometric factors. In seeding applications, for instance, the speed of the tractor is not likely to exceed 6 mph or so, although in spraying applications it may be considerably faster than this, up to 20 mph. Furthermore, in order to maintain the desired offset station when the implement navigates normal field turns, the marker vehicle should be able to accelerate very quickly to a speed as much as 3 times faster than that of the tractor.
This factor of 3 assumes that the marker is required to maintain an "outside"
station through turns that result in the "inside" end of the implement coming to a full stop, but in practice, turns this sharp are likely to occur only at the headlands, in which case the marker is commanded to go to the "follow" station behind the implement, and does not have to accelerate for the turn at all.
Thus a mobility specification for the vehicle to be capable of acceleration to twice its nominal speed within 1 second is adequate. Finally, the vehicle is able to turn around a radius of virtually zero, and reverse direction quickly, so that it can maintain an "inside" station through reasonably sharp turns.
The vehicle is able to operate for extended periods as long as 20 hours without any required attention from the operator. It is preferably diesel powered, so that it can be refuelled on the same schedule and with the same equipment as is used for the tractor. Minor mechanical servicing such as greasing of bearings, etc.
at 10 hour intervals is acceptable, but otherwise, the vehicle is designed and manufactured for a 200 hour maintenance interval. The vehicle should have a design life of at least 3000 hours, which should correspond to about 10 years of use for one seeding operation and one spraying operation over a typical western Canadian farming operation.
In Figure 6 is shown schematically in plan view an arrangement where more than two vehicles are arranged to be operated by a single operator in an operator cab 60 on the vehicle No. 1. The previously described arrangements allow vehicle No. 2 and vehicle No. 3 to have their position monitored relative to vehicle No. 1 and maintained at a set position relative to vehicle No. 1 for operating alongside vehicle No. 1. These vehicles can be used for various functions and one function schematically indicated is that of line painting where a painting device 61 is shown schematically generating a line 62 on the ground behind the vehicle. The relative position of the vehicles is thus maintained accurately so as to maintain the painted lines a predetermined distance apart. The system can provide adjustment of the spacing between the vehicles in the set operating position shown in full line in Figure 6 so as to adjust this spacing between the painted lines. The operator system has an input similar to that previously described which allows the adjustment of the space in between the vehicles.
The vehicles also have a second safe position indicated in dash line where vehicle no. 2 and vehicle 3 trail behind vehicle no. 1 for movement in a non operating mode from place to place. Again the operator system provides a setting which allows the vehicle to be moved to the safe position trailing behind the first vehicle where they are maintained in convoy behind the first vehicle by the control system. In a system using the ultra sonic distance detection sensors, the detection of the vehicle 3 relative to vehicle 2 is obtained by sensors on those two vehicles so that each vehicle detects the location of the next adjacent vehicle.
As previously described other functions may be carried out by similar vehicles designed specifically for those functions where the control of each vehicle is as set forth above to maintain spaced operating positions and a safe trailing position.
In such arrangements each of the vehicle carries out the same function and is basically the same design except that the first vehicle includes an operator control arrangement and a cab for containing the operator.
Turning now to Figure 7 there is shown a further arrangement in which a crop harvesting machine 70 indicated schematically as a combine harvester includes a crop discharge duct 71 for discharging into a transportation truck 72 for transporting the harvested crop to a storage location. It is highly desirable that this is carried out on the go so that the harvesting can continue as the discharge into the truck is carried out.
The combine harvester includes a cab 73 in which the operator is located. The truck also includes a cab 74 in which the truck drive is located.
However in the loading position as shown in Figure 7, the control by the operator in the cab 74 is replaced by control of the location of the truck relative to the crop harvesting machine to maintain the truck at a required position alongside the harvesting machine. Thus the truck operator switches over to a control mode in which the truck is basically maintained directly alongside the harvesting vehicle for a period of time for loading. In addition the control system controlling the position of the truck during the loading process includes an operator actuated system which allows forward and rearward motion of the truck as indicated at 75 relative to the combine harvester so that the load discharged from the discharge duct 71 is placed at different positions within the body of the truck.
The system therefore provides basically a fixed location of the truck relative to the harvesting machine but allows the operator simply to operate a lever controlling forward and rearward movement of the truck relative to the combine harvester effected by speeding up and slowing down. This forward and rearward movement can be effected simply by a single movement so that the operator can view the loading process and ensure that the truck is properly and evenly loaded for maximum load transportation.
Since various modifications can be made in my invention as herein above described, and many apparently widely different embodiments of same made within the spirit and scope of the claims without departing from such spirit and scope, it is intended that all matter contained in the accompanying specification shall be interpreted as illustrative only and not in a limiting sense.

Claims (20)

CLAIMS:

1. Apparatus comprising:
a first self-propelled independently steerable vehicle having a control system operable by an operator on board the first vehicle for controlling operation of the first vehicle;
the first vehicle being arranged to carry out a first function at a first location;
a second self-propelled independently steerable vehicle;
the second vehicle being arranged to carry out a second function at a second location spaced from the first location;
and a control device for controlling operation of the second vehicle relative to the first vehicle so as to be maintained in convoy by the control device with the first vehicle at a predetermined position relative thereto.

2. The apparatus according to Claim 1 wherein the control device includes an input arrangement for operation by the operator on the first vehicle so as to change the position of the second vehicle relative to the first vehicle.

3. The apparatus according to Claim 2 wherein the input arrangement is arranged to provide at least one set position for the second vehicle relative to the first at which the second vehicle is maintained by the control device.

4. The apparatus according to Claim 3 wherein the input arrangement is arranged to allow the operator to adjust the set position.

5. The apparatus according to Claim 2 wherein the input arrangement is arranged to provide a plurality of set positions for the second vehicle relative to the first vehicle which can be selected by the operator at each of which, when selected, the second vehicle is maintained by the control device.

6. The apparatus according to Claim 5 wherein the input arrangement is arranged to allow the operator to take over manual control of movement of the second vehicle as it moves from one set position to another in the event of meeting an obstacle.

7. The apparatus according to Claim 1 wherein the control device includes a first GPS unit mounted on the first vehicle at a predetermined location thereon to provide a first output corresponding to the GPS satellite signals received by the first GPS unit, a second GPS unit mounted on the second vehicle to provide a second output corresponding to the GPS satellite signals received by the second GPS unit, transmitters for transmitting the output data from each of the first and second GPS units to a computer, the computer being arranged to determine mathematically and repeatedly the positions of the first and second GPs units with respect to each other using the instantaneous GPS outputs from each of the two GPS units and indicating an instantaneous position of the location on the first vehicle as the first vehicle moves and control means for comparing the instantaneous position with the required position and for steering the second vehicle toward the required position in the event of a difference.

8. The apparatus according to Claim 1 wherein the control device includes ultrasonic distance measuring elements for detecting a distance between the first and second vehicles.

9. The apparatus according to Claim 8 wherein the control device comprises:
a first component mounted on the first vehicle and a second component mounted on the second vehicle;
one of the components including a timing signal transmitter for transmitting timing signals from said one component to a receiver on the other of the components;
one of the components including a first sound transmitter at a first location for transmitting first sounds at predetermined time intervals relative to the timing signals and a second sound transmitter at a second location thereon spaced from the first for transmitting second sounds at predetermined time intervals relative to the timing signals and the other of the components component having a sensor arranged to detect the first and second sounds;
and a processor for determining from the time of detection of the first and second sounds relative to the timing signals distances of the second vehicle from the first and second locations so as to calculate the position of the second vehicle relative to the first vehicle.

10. The apparatus according to Claim 8 wherein the control device comprises:
a first sensor system for mounting on the first vehicle for providing first outputs indicative of a direction and speed of movement thereof;
a second sensor system on the second vehicle for providing second outputs indicative a direction and speed of movement thereof;
and a processor arranged to compare the first and second outputs in conjunction with said detected distance and to effect control of the vehicle in dependence thereon.

11. The apparatus according to Claim 1 wherein the control device is operable to provide instructions defining at least two positions of the second vehicle relative to the first vehicle, each position being located at a predetermined distance beyond a respective end of the first vehicle.

12. The apparatus according to Claim 1 wherein the control device is operable to provide instructions defining at least three positions of the second vehicle relative to the first vehicle, each of two of the positions being located at a predetermined distance beyond a respective end of the first vehicle and a third of the positions being a retracted safe position adjacent to the first vehicle.

13. The apparatus according to Claim 12 wherein the retracted safe position is substantially directly behind a central portion of the first vehicle.

14. The apparatus according to Claim 5 wherein the control device includes a manual override control for guiding the second vehicle around obstacles to its required position.

15. The apparatus according to Claim 1 wherein the second vehicle is controlled by wireless communication.

16. The apparatus according to Claim 1 wherein the second vehicle carries a sensing system for sensing an obstacle in its path.

17. The apparatus according to Claim 1 wherein the first and second vehicles are arranged in a first relative position to carry out the same function at transversely spaced positions and include a second safe position of the second vehicle behind the first vehicle.

18. The apparatus according to Claim 1 wherein the first vehicle comprises a harvesting machine for harvesting an agricultural crop and wherein the second vehicle comprises a transport vehicle for carrying a load of the harvested crop and wherein the control device is arranged for the operator to control the position of the second vehicle relative to the first so as to load the crop at a position on the second vehicle as controlled by the operator.

19. The apparatus according to Claim 1 wherein the first vehicle includes an agricultural implement and wherein the second vehicle includes a ground marker for marking a required line of travel for the implement.

20. The apparatus according to Claim 19 wherein the ground marker device is arranged to generate a single line mark and the control device is arranged such that the single line is at a position spaced outwardly from an outer end of the implement.