On harbour sites unmanned vehicles and control systems for controlling these vehicles are developed, particularly for transport of containers, in order to reduce the cost of trans-shipment of such containers, to improve the logistics and speed of retrieving particular containers and/or to reduce the danger of accidents with such heavy vehicles.

In harbours containers are loaded from a ship onto a vehicle and then either taken to a temporary storage loca¬ tion or transported directly to a goods vehicle or train. The steerability for manoeuvering in confined spaces, is of importance for such so-called Automatic Guided Vehicles, as well as the controllability of the speed and the path along which the vehicle travels, for both ways of driving, viz forwardly and rearwardly. According to a first aspect the present invention provides an automatic guided vehicle (AGV) , comprising:

- a chassis or frame;

- at least two spaced axles, each having two or more wheels, and suspended in said frame; - a motor provided onto said frame for driving at least two wheels of at least two axles, at least one wheel at each side of the vehicle;

- steering means coupled to said wheels and for steering one or more axles at each side of said vehicle; and - control means arranged onto said chassis and adapted to control the motor and the steering means such as to automatically adjust the speed and direction of the vehicle depending on remote signals from guiding elements in the environment of the AGV. In the field of automatic guided vehicle technology steering of vehicles usually takes place by means of so- called axial pivot steering, wherein each wheel of a shaft has its own point of rotation in order to limit the space

required under a vehicle. With such steering arm control of the wheels on either side of a shaft, some slippage of the wheels occurs under particular conditions.

According to another aspect, the present invention provides a vehicle for transporting cargo, for instance of containers, in a harbour area, comprising:

- a first shaft provided with two or more wheels;

- a second shaft at a distance from the first shaft and provided with two or more wheels; - a steering device for steering the vehicle;

- control means for controlling the steering device on the basis of data transmitted remotely to the vehicle; and

- drive means for driving at least one wheel of each of the shafts, - wherein the steering device is embodied such that the wheels not forming part of the same shaft have a roughly equal angle relative to the travel direction when the ve¬ hicle is steered.

The shafts are preferably rigid so that it is possible to suffice with driving of one or a number of mutually coup¬ led wheels on one side of each shaft. If the steering of the rigid shafts takes place in correct manner from the control means, it is not only possible to travel crabwise but also to negotiate a sharp bend, while slippage of wheels is avoi- ded as far as possible.

A rigid shaft can further be steered electrically, which reduces the danger of leakage of hydraulic fluid and moreover facilitates servicing. This is all the more impor¬ tant as perhaps in the future the driving of such unmanned vehicles must also be take an electrical form, since no leakage of environmentally-damaging liquid can herein occur.

Known systems for controlling unmanned vehicles in a harbour area require considerable adaptation of the harbour area, such as active or passive guide elements to be arranged in channels in the ground. Even in the construction of new harbours this entails considerable costs.

According to a further aspect the present invention provides a system for controlling one or more vehicles, comprising:

- a transmitter and a receiver for transmitting respec- tively receiving microwaves mounted on board the vehicle; and

- beacon elements which can be erected fixedly in the area and which reflect the microwaves such that they can be distinguished by the receiver from other reflecting objects disposed in the surrounding area.

The beacon elements can be erected at comparatively low cost in an existing harbour location or one to be newly constructed.

Operation preferably takes place at a frequency of about 95 GHz and/or with pyramid-like beacon elements, as it has been found that the microwave or radar radiation reflec¬ ted against these beacon elements are very well distinguish¬ able from other objects, such as containers, cranes and the like, disposed in the surrounding area. The vehicle has in fact no front or rear and preferably has the same performance characteristics in both directions. One pair of wheels is preferably driven on each of the sides of the vehicle. By using - in a vehicle with two shafts - pairs of wheels at a time instead of single wheels, commer- cially available tyres for vehicles can be used for the desired load capacity instead of tyres suitable for an air¬ craft in the case of single wheels.

On each of the sides of the vehicle at least one of the wheels is preferably provided with a speed and/or position detector, preferably a non-driven wheel, so that the posi¬ tion and/or speed can be transmitted to the central computer or control unit of the vehicle.

In preference the wheels are driven using hydraulic motors which are driven in turn by a central pump so that the vehicle can be maneuvered more easily; these hydraulic motors preferably have two stroke volumes, wherein a small stroke volume can be used at relatively high speeds while a greater stroke volume is used at low speeds and during mov-

ing off. The diesel engine will preferably at a low number of turns per minute, such as to minimize pollution.

When the control system for the vehicle is combined with the accurate drive and the regulating system coupled thereto, in the computer of the control system the position of the vehicle in relation to the beacon elements can be compared, for instance once or twice per second, with the signals obtained in the computer on the basis of the travel data. Both the distance to and the direction to the beacon elements are recorded on board the vehicle. Stored in the computer is an area map of the site and the positions of the beacons thereon.

Further advantages, features and details will become apparent in the light of the description of the preferred embodiment thereof with reference to the annexed drawings, in which: fig. 1 shows a view in perspective of a vehicle accor¬ ding to the present invention making use of a control system according to the present invention in a harbour location; fig. 2 is a view in section along the line II-II in fig. 1; fig. 3 is a view in section along the line III-III in fig. 1; fig. 4 shows a diagram of the steering of the wheels of the vehicle of fig. 1; and fig. 5 shows a diagram of the control of the drive of the vehicle of fig. 1. fig. 6 shows a view in perspective of a second prefered vehicle according to the present invention in a harbour location; fig. 7 is a schematic top view of the vehicle of fig. 1; and fig. 8 is a top view of a third preferred embodiment of a vehicle according to the present invention. In a harbour location (fig. 1) containers C are loaded using a crane K from a ship S onto unmanned vehicles 1, l'. Beacon elements 2 are erected at fixed positions in the area in which vehicle 1 can travel round unmanned. Such beacon

elements are known per se and are of a form and provided with a coating such that the microwave radiation transmitted from the vehicle at a frequency of about 95 GHz can be suf¬ ficiently well distinguished in recognizable manner from other metal objects in the harbour area by microwave recei¬ vers likewise attached to the vehicle. The microwave radia¬ tion transmitted on both sides of the vehicle is indicated in fig. 1 with dash-dot lines.

The chassis 3 of the vehicle is designed for a useful load capacity of 60 tons (60,000 kg), for instance divided over two containers with a length of for example 20 feet. Suspended on each of the sides of the chassis is a respec¬ tive shaft 4, 5 each provided on both sides with two wheels 6, 7 and 8, 9 respectively, so that these wheels can be provided with commercially available tyres for the said load capacity. Fixed centrally on the chassis for driving the vehicle is a diesel motor 10 which is coupled crosswise via a continuously adjustable axial plunger pump and via the conduits 11 (see also fig. 2) and 12 to hydraulic motors 13 and 14 respectively (see also fig. 2) for driving the wheels 8, 9 and the wheels 15, 16 located diagonally opposite.

In a manner not shown, the vehicle 1 is also provided with a control unit or computer which, on the basis of com¬ mands to be given remotely to the vehicle, causes the vehi- cle to travel along the desired path to the desired destina¬ tion. Use is herein made of the microwave radiation reflec¬ ted by beacon elements 2 and also of the position and/or speed detectors arranged at the non-driven wheels 6, 7 and 17, 18 for detecting the position and/or speed of these wheels.

In preference the containers are placed on the vehicle on weighing elements (not shown) which are coupled electri¬ cally to the control unit so that account is taken by the control unit of performance depending on that weight such as the circumference of the tyres and the like.

The wheels 8, 9 (fig. 2) are suspended on chassis 3 and are driven via the hydraulic motor 14. Rims 22, 23 of the respective wheels 8, 9 are fixed to a planetary wheel hub 24

provided with a brake drum 25 which is actuable by means of a spring braking cylinder 26 and a brake key 27.

The steering of the wheels 8, 9, for instance from the position drawn in full lines to the position drawn in broken lines, takes place using a hydraulic cylinder 20, wherein the steering is controlled from the control unit of the vehicle. In the embodiment shown, the steering of wheels 8, 9 is connected via track rod 21 to the steering of wheels 17, 18 (see fig. 1) . The position of wheels 8, 9 and therefore the steering angle α and the wheel deflection is transmitted to the con¬ trol unit of the vehicle via a position detector not shown in fig. 2.

From the control unit a bias value 41 (fig. 4) for the steering angle is transmitted to an D/A (digital to analog) converter 42. The analog signal is transmitted to a PI regulating means 43 which controls valve 44 for feed of hydraulic medium to the steering cylinder 20. The position detector for the position of the wheels 8, 9 is designated schematically in fig. 4 with 45, wherein the position detected by the position detector forms negative feedback in junction point 46 with the signal value coming from the D/A converter 41. The lower part of fig. 4 relates to the corresponding control diagram for steering the wheels 15, 16 on the other side of the vehicle which are steered in similar manner as described above with reference to fig. 2, wherein the bias value for the steering of the wheels is of course coupled to both sides of the vehicle. The steering is further provided with a manual steering member or joystick 47 which can intervene in the control diagram in the manner shown in fig. 4.

The wheels 6, 7 (fig. 3) (and the wheels 17, 18) are provided with a schematically designated detector 30 which transmits the position and/or speed of wheels 6, 7 via elec- trie line 31 to the control unit on board the vehicle. De¬ tector 30 is disconnectable by loosening screw bolts 32, 33 and by removing from coupling part 34 the coupling part 35 connected to detector 30. Coupling part 34 is fixedly con-

nected to shaft 36 which can rotate in bearing 40. The other end of shaft 36 is fixed to a hub cover 37. Lubricating oil O is contained in hub carrier 38 of wheel hub 39 (with brake drum) in which shaft 36 can rotate. The driving of vehicle 1 (fig. 5) takes place via hyd¬ raulic motors 14 which receive hydraulic medium fed from a pump 51, the quantity of which is regulated from a regulat¬ ing member 52. The movement of the vehicle is directly mea¬ sured via position detectors 30, 30' at wheels on both sides of the vehicle. The output of the position detectors 30, 30* is transmitted to pulse counters 53, the results of which are added up and averaged in an amplifier 54 with an ampli¬ fication factor of 0.5. The output of amplifier 54 forms negative feedback to the output of a D/A converter 55 which as input receives a digital bias value fed from the central control unit on board the vehicle, which bias value is de¬ signated with 56. The output of the D/A converter 55 is coupled via junction point 57 to a PI regulator 58. The latter can, when the switches SI, S2, S3, S4 and S5 are connected in a manner suitable for this purpose, control the regulating means 52. The control on the basis of the posi¬ tion of the wheels takes place at low speeds of the vehicle, for instance when moving off and during approach to a load¬ ing/unloading location for the containers. In the shown position of the switches S1-S5 control of the movement of the vehicle 1 takes place on the basis of the speed of the vehicle, wherein use can be made of the same position detectors of the wheels. For easy reference in the diagram the detectors for the speed are designated with 60, 60'. These are connected to an output of a differentiat¬ ing means 61 (or pulse counter) . In the shown position of the switches S1-S5 the outputs of the speed detectors 60, 60' form via junction point 62 negative feedback to junction point 63 which on the other side is coupled via switches S2 and SI to a D/A converter 64 which receives a desired bias value 65 from the control unit on board the vehicle. The output of junction point 63 is fed to a P regulator 66 which is coupled via junction point 67 to the regulating member

52. The speed control outlined here takes place at higher speeds of the vehicle, since this control is more rapid and sufficiently accurate. This relates to speeds of the vehicle of for example 2-6 m/s. The diagram of fig. 5 further provides control on the basis of the acceleration of the vehicle, for which purpose an acceleration detector 68 is coupled on one side to a double differentiating means 69 and on the other side via switch S5 to a P regulator 70. Finally, it is possible to drive the vehicle 1 manually via joystick 71.

The control unit or computer on board the vehicle has to take account of a large number of input signals. In the chosen configuration use is made of a central processor unit or status manager which is coupled to for instance three or more processor units or transputers and which delivers the relevant commands to the transputers in the desired sequen¬ ce. A first transputer serves to provide the remote communi¬ cation between the vehicle and a main computer which is arranged in the harbour area and which gives drive commands to the vehicle. It is also possible via the remote communi¬ cation to transmit alterations in the area map of the har¬ bour location and the beacon elements disposed therein.

With reference to the commands from the main computer the status manager enters into communication with that tran- sputing part in which the area map is stored and which is adapted to determine the routing of the vehicle.

The actual travel of the vehicle takes place under the control of a pilot transputer which operates the above des- cribed regulation system for driving and steering the vehi¬ cle and furthermore compares the information obtained via the receivers by the reflected microwaves with the infor¬ mation obtained on the basis of the position and/or speed detectors in combination with steering information, as obtained from respective sensor or detector means.

The pilot transputer is further adapted to recognize obstacles such as individual containers encountered on the plotted route and thus to bring the vehicle to a stop.

An important other transputing part coupled to the status manager relates to the safety and the monitoring of the state of the vehicle. It can be seen in fig. 1 that the vehicle is provided with compressible buffer elements on both sides of the vehicle which are provided in a manner not shown with detectors, so that the vehicle comes to an im¬ mediate stop when it collides with an obstacle. In addition the vehicle is preferably equipped with brakes which spring back mechanically and which brake the vehicle as soon as problems occur, for instance in the hydraulic brake system of the vehicle. It can also be ensured that from the main computer on the harbour location a signal is transmitted continuously to each unmanned vehicle so that, if this sig¬ nal ceases, the unmanned vehicle comes to an immediate stop. In the case of small variations in determined reference values for oil pressure and the like, the status manager can direct the vehicle to a workshop where a service can then be carried out.

The above described vehicle and control system therefor are not limited to the shown and described embodiment. A number of variations are conceivable within the scope of the following claims, such as:

- arranging more than two shafts and/or more or fewer wheels per shaft; - driving wheels not situated diagonally opposite each other;

- measuring speed and/or position on the driven wheel; and

- driving the vehicle in a manner wholly other than with the aid of the shown and described hydraulic motors.

In a harbour location (fig. 6) containers C are loaded using a crane K from a ship S onto unmanned vehicles 101, 101' .

The chassis 103 of the vehicle is designed for a useful load capacity of 60 tons (60,000 kg), for instance divided over two containers with a length of for example 20 feet. Suspended on each of the sides of the chassis is a respec¬ tive shaft 104, 105 each provided on both sides with two

wheels 106, 107 and 108, 109 respectively, so that these wheels can be provided with commercially available tyres for the said load capacity. Fixed centrally on the chassis for driving the vehicle is a diesel motor 110 which is coupled via a continuously adjustable axial plunger pump and via the conduits 111 and 112 to hydraulic motors 113 and 114 respectively for driving the wheels 108, 109 and the wheels 115, 116 located diagonally opposite.

In a manner not shown, the vehicle is also provided with a control means or computer which, on the basis of commands to be given remotely to the vehicle, causes the vehicle to travel along the desired path to the desired destination. Use can herein be made of either microwave radiation reflected by beacon elements or guide elements arranged in the ground which remotely provide the vehicle with area information, or position and/or speed detectors arranged at the non-driven wheels 106, 107 and 117, 118 for detecting the position and/or speed of these wheels, in addition to detectors detecting the steering angle. In preference the containers are placed on the vehicle on weighing elements (not shown) which are coupled electri¬ cally to the control unit so that account is taken by the control unit of performance depending on that weight such as the circumference of the tyres and the like. The wheels 108, 109 are suspended on chassis 103 and are driven via the hydraulic motor 114.

Crabwise travel, that is, driving at an angle relative to the longitudinal axis of the vehicle, is illustrated particularly well in fig. 7. The shafts 120 with wheels 106, 107, 115 and 116 and shafts 121 with wheels 108, 109, 117 and 118 are thereby rotated at the same angle by means of respective discs 122 and 123 which are provided with a toothing onto which engage electrically drivable pinions 124 and 125 respectively 126 and 127 which can transmit the forces required for steering.

In the embodiment according to fig. 8 discs 132 and 133 are controlled by means of hydraulic plungers 134 and 135,

respectively 136 and 137 arranged diametrically opposite each other.

As will be apparent, a sharp bend can be negotiated by the vehicle according to the present invention when the shafts assume an anti-parallel position in the vehicle, wherein the radius of the bend is determined by the inter¬ section of the axes of the shafts.

The shown and described embodiment according to the present invention is capable of travelling in both direc- tions, while on both sides of the vehicle the wheels on one end of a shaft are driven, preferably the wheels located diagonally opposite one another. The steering of the vehicle becomes simple, wheel slippage is virtually excluded, while a single steering transmission can suffice per shaft. Each wheel is preferably provided, in a manner not shown, with a position and/or speed detector for measuring the speed and the path covered by the vehicle and also for detecting whether any of the wheels has suffered a puncture. The present invention is not limited to the shown and described embodiment; the rights are rather defined by the following claims.

A four- (or multi-) shafted vehicle is likewise con¬ ceivable.

In a prefered embodiment of the automatic guided vehicle according to the present invention a hydraulic brake is used, such as to have a water braking resistance better than the diesel engine alone. The feed pump can dissipate energy at high pressure (±275 bar) -at normal drivings it operates at a pressure of about 14 bar- such that braking time is reduced and therefor also the total time needed for loading/unloading. The additional hydraulic brake can be activated automatically, e.g. when the number of resolution of the diesel engine exceeds a certain value.

In the diagrams shown in figure 4 and 5 a number of discrete hardware components is indicated; in a further embodiment a number of functions, D/A convertering, switches and P/D control is embodied in a computer, partly in software. The detectors or sensors for measuring position

and velocity respectively, can be combined into a single position sensor, of which the sensing value is corrected into speed information by differentiating.