Background of the I nvention

(00011 The resent invention relates to a conveyor vehicle for use in a conveyor train, a conveyor train and an apparatus for controlling a conveyor train.

Description of the Prio r Art

[0002] The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that the prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates,

[0003] The processes for mining coal from underground seams have bee refined and developed for many years. One key activity common to all mining designs is to develop "roadways" which are tunnels mined to provide access throughout the mine. There are many uses for such tunnels and the mining methods employed v ary substantially.

[0004] A mining machine which cuts coal in the process of developing the tunnel ha to transport the Cut coal away from the face. Batch processing systems that employ mobile vehicles have been employed extensively in many mines but this method is inherently a non- continuous method and as such suffers delays as the vehicles flit between the cutting machine and the conveying belt system that transports coal to surface. While the conveying vehicles are flitting the cutting machine cannot cut coal, thus causing delays and interruptions,

[0005] in the 1.950' s American miners began to employ conveying systems that link the cutting machine and mine conveyor belt system by coal conveying means that could allow "continuous haulage" of coal. This method allows continuous production of coal as the tunnels are mined. Cascading conveyor chains, cascading conveyor belts and even a bending conveyor belt have been developed by many companies and used over several decades in an attempt to improve roadway (tunnel) development rates. [0006] The use of cascading conveyors has proven to be practical and productive but the systems built to date have all been limited by the reliability of the conveying car steering systems- In this regard, the majorit of systems indirectly measure the angle between cars, which is necessary to compute the steering inputs required to maintain the train's correct locus. Indirect measurement is undesirable due to the potential for inaccuracy in the measurement, which in turn can result in problems in correct steering of cars in the train,

[0007] US-5,3-66,059 describes a. steering system for steering a plurality of conveyor vehicles connected together in the form of a train. The vehicle has a first pair of wheels which can be steered by an operator as the train moves. There are further pairs of steerable wheels connected to the second and subsequent vehicles in the train and supporting same. There are hydraulic cylinders for steering each of the pairs of steerable wheels on the second and subsequent vehicles and a control mechanism for controlling these cylinders in order to set the steering angle of each further pair. This control mechanism includes means for determining the current steering angle of the first pair of wheels and generating an electrical signal indicative thereof and means for storing a series of these electrical signals as the train is travelling. Further means determine the amount of time the wheels in the train have been travelling and there is a calculator for determining the location of each of the further pairs of wheels on the basis of the determined travel time. A second electrical signal is generated for each further pairs of wheels in order to control its respective hydraulic cylinder and thereby set the steering angle of each pair at the same steering angle that the first pair of wheels had when they were at that location.

[0008] WO2008/138 101 describes steering system and method are capable of steering a plurality of vehicles, such as mobile conveyors, arranged in a train with adjacent vehicles pivotally connected to each other for movement about a vertical axis. Each vehicle has a pair of steerable wheels with one pai at one end of the train being a selected leading pair having its steering angle determined by an operator. An electrical control system automatically steers all of the wheels trailing behind the leading pair. Vehicle angle sensors measure iiitercar angles between adjacent vehicles and provide this information to the control system, There is an indicator for providing the controlle with the current distance travelled by the train. Wheel angle sensors provide signals indicative of the current steering angle for each pair of wheels in the train. The controller adjusts the actual steering angle for each trailing pair to a desired angle by calculating adjustments based on the distance travelled, a stored series of sensed steering angles, and the current inter-car angles for the respective trailing pairs.

[0009] WO20Q8/G953G2 describes a hitch apparatus for use on a first mobile machine such as a conveyor vehicle to be used with a second mobile machine connected to the first machine. The apparatus includes a track member adapted for mounting at an end of the first machine, this member providing a track having two opposite sides and bent to form a circular arc having a centre of curvature, A hitch unit is mounted for rolling movement on the track a d can pivotably connect the end of the first machine to the second machine. The hitch unit includes rollers for engaging both of the opposite sides so that the track is captured between the rollers. The first machine is able to pivot about a substantially vertical axis extending through the center of curvature relative to the second machine and is connected to the second machine for movement therewith,

[0010] These systems also use indirect measurement of inter-car angle using a chai and sprocket arrangement, which is unreliable, Additionally, they employ a complex coupling between cars that relies on a curved rail. Consequently, these arrangements tend to be complex and hence expensive and prone to failure, as well as unreliably steering the entire train of conveyors in some situations. Additionally, the arrangements control steering of cars based on both an inter-car angle and a steering angle of a proceeding car, which tends to be complex and unreliable.

[0011] O2013110195 and O20131 10196 describe an alternative conveyor system including a hitch apparatus for connecting a self-propell d trailing vehicle to a self-propelled leading vehicle, which allows for a varying inter-car distance. The hitch apparatus includes: a first hitch assembly for connecting a rear end of the leading vehicle to a front end of the trailing vehicle; a first angle sensor operative! connected to a pivot shaft and capable of measuring a horizontal angle between a centerline of a swivel base extending through a pivot shaft and a longitudinal centerline of the leading vehicle; a second hitch assembly for mounting on the front end of the trailing vehicle, the second hitch assembly including a connecting device mounted on the front end of the trailing vehicle and connective to the swivel base of the leading vehicle; and a distance sensor for measuring a variable distance between a preselected point at the front end of said trailing vehicle and the swivel base.

[0012] In the above described arrangements, the speed of adjacent cars is controlled to adjust the inter-car distance. Additionally, angle sensors are provided on both the upstream and downstream side of the hitch, with steering being controlled based on the combination of both measured angles. This further complicates the complexity of the steering system, which can lead to unreliability and poor steering control.

Summary of the Present Invention

[0013] In a first broad form the present inventio seeks to provide a conveyor vehicle for use in a conveyor train, the conveyor vehicle including:

a) a frame;

b) a pair of wheels mounted on opposi g sides of the frame;

c) a steering system for steering the wheels,

d) a drive for driving the wheels:

e) a number of belt rollers mounted to the frame;

fj a endless conveyor belt supported by the belt rollers for transporting material from a loading region to a discharge region in use;

g) at least part of a vehicle coupling for attaching the conveyor vehicle to a adjacent conveyor vehicle in the conveyor train in use; and,

h) an angle sensor coupled to the vehicle coupling that senses a relative angle between the conveyor vehicle and the adjacent conveyor vehicle, wherein the relative angle and a distance travelled by at least one conveyor vehicle in the conveyor train are used in controlling a drive torque and steering angle of the wheels of one of the conveyor vehicles in the conveyor train.

[0014] Typically the vehicle coupling is positioned substantially vertically inline with the loading region in use.

[0015] Typically the vehicle coupling is positioned above the belt in use.

[0016] Typically the vehicle coupling includes a ball and vehicle socket arrangement. [0017] Typically the conveyor vehicle includes:

a) a socket proximate one end of the vehicle for coupling to a ball of a first adjacent vehicle; and,

b) a ball proximate an opposing end of the vehicle for coupling to a socket of a second adjacent vehicle.

[0018] Typically the angle sensor includes a rotary transducer mounted in the vehicle coupling.

[0019] Typically the angle sensor is mounted in a socket and coupled to a vehicle ball of an adjacent vehicle via a rotatable shaft and at least one universal joint.

[0020] Typically a pivot point of the vehicle coupling is positioned substantially a mid point between wheels of the conveyor vehicle.

[0021] Typically the drive system includes:

a) a hydraulic motor coupled to each wheel;

b) a hydraulic pump; and,

c) a fluid conduit for transferring a hydraulic fluid from the hydraulic pump to each hydraulic motor.

[0022] Typically the torque applied to the wheels is controlled by adjusting a pressure of the hydraulic fluid.

[0023] Typically at least one conveyor vehicle in the vehicle train includes a distance sensor that measures a distance travelled by the conveyor vehicle and wherein the distance sensor senses rotation of at least one wheel .

[0024] Typically the rotation sensor includes a star wheel mounted to the wheel and a proximity sensor.

[0025| Typically at least one conveyor vehicle in the vehicle train includes a controller for controlling a drive torque and steering angle of the wheels of one of the conveyor vehicles in. the conveyor train. [0026] Typically the controller includes an electronic processing device that: a) receives an indication of the relative angle from the angle sensor;

b) receives an indication of the distance from a distance sensor; and,

c) at least partially controls the drive torque and steering angle in accordance with the relative angle and distance travelled.

[0027] Typically the controller is coupled to at least one of:

a) the steering system;

b) the dri ve.

[0028] Typically the controller is coupled to angle sensors, steering systems and drives of multiple conveyor vehicles.

[0029] Typically the controller receives an indication of relative angles for multiple conveyor vehicles and wherein for a vehicle heading in a straight direction, the controller reduces the drive torque of the conveyor vehi cle in the event that at least one forward conveyor vehicl e is turning.

[0030] Typically the controller:

a) determines a reference relative angle between a leading pair of conveyor vehicles and at one or more reference positions;

b) monitors a distance travelled by at least one conveyor vehicle in the conveyor train; and,

c) controls the drive torque and steering angle so that the relative angle between each other pair of conveyor vehicles is the same as the reference relative angle at each of the one or more reference positions.

[0031] In a second broad form the present invention seeks to provide apparatus for use in controlling a conveyor vehicle of a conveyor train, the apparatus including a controller having an electronic processing device that:

a) determines a distance travelled by at least one conveyor vehicle in the conveyor train using a di tance sensor;

b) determines a relative angle between the conveyor vehicle and an adjacent conveyor vehicle using an angle sensor coupled to a vehicle coupling; a d, c) controls at least one of a drive torque and steering angle based on the relative angle and the distance travelled.

[0032] Typically the controller:

a) receives an indication of the relative angle from t e angle sensor;

b) receives an indication of the di tance from the distance sensor; and,

c) at least partially controls the drive torque and steering angle in accordance with the relative angle and distance travelled.

[0033] Typically the controller is coupled to at least one of:

a) a steering system; and,

b) a drive.

[0034] Typically the controller is coupled to angle sensors, steering systems and drives of multiple conveyor vehicles.

[0035] Typically the relative angle is an angle between the conveyor vehicle and at least one adjacent forward conveyor vehiele forward from of conveyor vehicle in a direction of vehicle travel .

[0036] Typically the controller:

a) determines a reference relative angle between a leading pair of conveyor vehicles and at one or more reference positions;

b) monitors a distance travelled by at least one conveyor vehicle in the conveyor train, and,

c) controls the drive torque and steering angle so that the relative angle between each other pair of conveyor vehicles is the same as the reference relative angle at each of the one or more reference positions.

[0037] In a third broad form the present invention seeks to provide a conveyor train including a number of conveyor vehicles, each conveyor vehicle including:

a) a frame;

b) a pair of wheel s mounted on opposing sides of the frame;

c) a steeri g system for steering the wheels; d) a drive for driving the wheels;

e) a number of belt rollers mounted to the frame;

f) an endless conveyor belt supported by the belt rollers for transporting material from a loading region to a discharge region in use;

g) at least part of a vehicle coupling for attaching the conveyor vehicle to an adj acent conveyor vehicle in the conveyor train in use; and,

h) an angle sensor coupled to the vehicle coupling that senses a relative angle between the conveyor vehicle and the adjacent conveyor vehicle, wherein the relative angle and a distance travelled by at least one conveyor vehicle in the conveyor train are used in controlling a drive torque and steering angle of the wheels of one of the conveyor vehicles in the conveyor train.

[0038] Typically the conveyor train includes:

a) a loading vehicle at one end;

b) a discharge vehicle at another opposing end; and,

c) at least one intermediate vehicle positioned between the loading and discharge vehicles.

[0039] In a fourth broad form the present invention seeks to provide a method of controlling a conveyor vehicle of a conveyor train, the method including, in a controller having an electronic processing device;

a) determining a distance travelled by at least one conveyor vehicle in the vehicle trai usi g a distance sensor;

b) determining a relative angle between the conveyor vehicle and an adjacent conveyor vehicle using an angle sensor coupled to a vehicle coupling; and, c) controlling at least one of a drive torque and steering angle based on the relative .angle and the distance travelled.

Brief Description of the Drawings

[0040] An example of the present invention will now b described with reference to the accompanying drawings, in which: - [0041] Figure 1 A is a schematic side view of an example of a conveyor vehicle for use in a conveyor train;

[0042] Figure IB is a schematic plan view of the conveyor vehicle of Figure t A;

[0043] Figure 1C is schematic side view of two coupled convey or vehicles of Figure 1 A;

[0044] Figure ID is a schematic plan view of two coupled conveyor vehi cles of Figure 1A;

[0045] Figure 2 is a schematic plan view of an example of a conveyor train including conveyor vehicles of Figure 1A;

[0046] Figure 2B is a schematic plan view of the conveyor train of Figure 2A illustrating turning of the conveyor train;

[0047] Figure 3 is a schematic diagram of an example of a controller;

[0048] Figure 4A is a schematic plan view of an example of a conveyor train travelling in the first direction;

[0049] Figure 4B is a schematic plan view of an example of a conveyor train travelling in a second direction;

[0050] Figure 4C is a schematic plan view of an example of a conveyor train progressively turning;

[0051] Figure 4D is a schematic plan view of an example of adjusting conveyor vehicle drive torque;

[0052] Figur 5 A is a schematic side view of a specific example of two conveyor vehicles;

[0053] Figure 5B is a schematic perspective view of the conveyor vehicles of Figure 5A;

[0054] Figure 5C is a schematic side view of the conveyor vehicles of Figure 5A with a relative incline;

[0055] Figure 5D is a schematic close up of the vehicle coupling between the conveyor vehicles of Figure 5 A; and,

[0056] Figure 5E i s a further schematic close up of the vehicle coupling of Fi gure 5D . Detailed Description of the Preferred Embodiments

[0057] An example of a conveyor vehicle for use in a conveyo train will now be described with reference to Figures 1 A to ID. [0058] In this example, the conveyor vehicle 100 includes a frame 1.10, a pair of wheels 1.61 mounted on opposing sides of the frame, and a drive and steering system 160 for driving and steering the wheels.

[0059] A number of belt rollers 121, 122, 123, 124 are mounted to the frame 1 .10, with an endless belt 130 being supported by the belt rollers 121, 122, 123, 124 for transporting material from a loading region 131 to a discharge region 132 in use.

[0060] The conveyer vehicle 100 includes at. least part of a vehicle coupling 140 for attaching the conveyor vehicle 100.1 to an adjacent conveyor vehicle 100.2 in use, as shown for example in Figures lC and ID. An angle sensor 150 is coupled to the vehicle coupling 140 and senses a relative angle (also referred to as the "inter-car" angle "IC") between the conveyor vehicle 1 0. 1 and the adjacent conveyor vehicle 100.2.

[0061] At least one of the conveyor vehicles in a conveyor train includes a distance sensor that measures a distance travelled by the conveyor vehicle and hence the conveyor train. Whilst this could be achieved in any suitable manner, in one example this is performed by measuring rotation of the wheels, to thereby provide a direct measurement of the distance travelled.

[0062] I use, the relative angle and distance travelled by at least one vehicle in a conveyor train are used in controlling a drive torque and vehicle steering angle of the wheels 161 of one of the conveyor vehicles in the conveyor train, which could be either the conveyor vehicle 100, 1 or one or more other conveyor vehicles 100.2,

[0063] B having the conveyor vehicles use an angle sensor 150 coupled to the vehicle coupling 140, this allows for direct sensing of the relative angle between the conveyor vehicles, which in turn helps ensure accurate sensing of the relative angle. Similarly, directly measuring the distance travelled, for example by measuring wheel rotation, provides a more accurate measure of distance travelled. Consequently, this allows for more accurate steering control of each of the conveyor vehicles,

[0064] Furthermore controlling both the drive torque and steering angle of the conveyor vehicles ensures that the rearward conveyor vehicles more accurately follow the path of the lead vehicle, allowing the system to be used reliably even with large numbers of conveyor vehicles. In particular, this accommodates the different distances that are traversed as the conveyor vehicles travel round corners as opposed to in. straight lines, whilst also controlling the relative force between conveyor vehicles, winch in turn helps prevent understeer and oversteer situations, which frequently arise in traditional conveyor steering systems.

[0065] Accordingly, the above described arrangements make the conveyor system more practical and reliable than traditional arrangements, and allows recording of steering angles of the conveyor vehicles to be avoided.

[0066) Thus the above arrangements eliminate the steering limitations experienced by traditional cascading belt type systems and corresponding steering controls. This allows the conveyor vehicles to be used as part of a conveyor train, an example of which is shown in Figures 2A to 2B.

[0067] As shown the conveyor train 200 includes a loading vehicle 210 at one end, a discharge vehicle 220 at another opposing end and at least one intermediate vehicle 230 positioned between the loading and discharge vehicles 210, 220. It will be appreciated that the intermediate vehicles 230 correspond to the conveyor vehicle 100 of Figures ! A to ID, whilst the loading and discharge vehicles 21 , 220 are modified to provide additional functionaiity, as will, be described below.

[0068] In use, material ca be loaded onto the conveyor belt 130 of the loading vehicle 210, and then transported progressively in a transport direction, as shown by the arrow 241, along the conveyors 130 of the intermediate vehicles 230, to the discharge vehicle 220, where it is discharged.

[0069] Additionally, to allow the conveyor train 200 to drive into and out of a mine, or other area, the loading and discharge vehicles 210, 220 may each be capable of being used as a lead vehicle to drive the conveyor train 200. Accordingly, it will be appreciated that the conveyor train 200 can travel forwards or backwards relative to the transport direction 241, with the remaining conveyor vehicles 210, 220, 230 following the lead vehicle. [0070] To achieve this, the conveyor vehicles 210, 220, 230 are typically controlled using a controller having an electronic processing device that receives an indication of a relative angle between each conveyor vehicle and an adjacent conveyor vehicle from the angle sensor 150, as well as an i dication of a distance travelled by at least one of the conveyor vehicles in. the conveyor train from a distance sensor. The electronic processing device then controls at least one of a vehicle dri ve torque and vehicle steering angle of the conveyor vehicles. This allows single end conveyor vehicle, such as the loading or discharge vehicle 210, 220, to he used as a lead vehicle, with this being directed by an operator or autonomous steering system, and with rearward conveyor vehicles following behind, by controlling the steering and drive torque based on the relative angles and distance travelled, as will be described in more detail below.

[0071 ] A number of further features will now be described,

[0072] In one example, the frame 110 includes substantially parallel spaced apart longitudinal frame members 1 11, extending substantially along the length of the conveyor vehicle 100, The longitudinal frame members 1 1 1 include a sloping mid portion 1 1 1 , 1 so that the discharge region 132 is raised relative to the loading region 131. This assists in supporting the conveyor belt 130 on an incline so that material can be discharged from one conveyor vehicle 1.00,2 to an adjacent conveyor vehicle 100,1, as well as assisting with positioning of the vehicle coupling 1.40, as will be described in more detail below.

[0073] The longitudinal frame members 1 1 1 are interconnected by a number of lateral frame members 112 with four being shown in this example for the purpose of illustration only. The longitudinal and lateral frame members 1 1 1 and 112 can be formed from any suitable frame member such as rectangular hollow section steel frame members, or alternatively more light weight aluminium extrusions or the like, depending on strength and weight requirements.

[0074] The frame 110 further includes a vehicle coupling support 114 that supports a ball 142 for mating with a cooperating socket 141 of the vehicle coupling 140 on a adjacent conveyor vehicle 100.2, as will be described in more detail below.

[0075] A drive roller support 1 15 extends downwardly from the longitudinal frame members i l l to support a drive roller 121. Idler rollers 123, 124 are supported by support 1 1.6 extending upwardly from the longitudinal frame members 1.1 1, whilst the return path roller 122 is supported directly by the elongate frame members 1 1. In each case, the drive, idler and return path rollers 121 , 122, 123, 124 are mounted on respective axles coupled to the corresponding support 1 15, 1 16 and the longitudinal members 111 , as will be appreciated by persons skilled in the art.

[0076] In use, the roller 121 typically acts as a drive roller and is coupled to a conveyor drive, such as a suitable motor (not shown), mounted on the frame 110. The idler rollers 123, 124 operate to support the conveyor belt 130 on transport and return paths respectively, whilst the roller 122 operates to transfer the conveyor belt 130 from the retur to the transport path. The idler and/or return rollers 122, 123, 124 may be biased in order to maintain tension in the conveyor belt 130. Additionally, the idler rollers 123, 124 may be angled to provide the belt with a generally 'LP or Ύ" shaped configuration along at feast an intermediate portion of the transport path, which can assist with ensuring material is retained thereon. Although four rollers 121, 122, 123, 124 are shown this is for the purpose of example only and is not intended to be limiting, and in practice any number of rollers required to support the conveyor belt 130 may be used.

[0077] In the example of Figures 1A to ID, the drive and steering system 160 includes a separate steering mechanism and drive, in one example, each of the wheels 161 can be steered independently, but more typically the wheels are linked by a common steering bar so that wheels .are steered i conjunction using a suitable actuator system, such as a hydraulic steering system. The drive typically includes a hydraulic motor coupled to each wheels, a hydraulic pump and a fluid conduit for transferring a hydraulic fluid from the hydraulic pump to each hydraulic motor. In this example, the torque applied to the wheels is controlled by adjusting a pressure of the hydraulic fluid using the hydraulic pump, with a "T" connector being used so that fluid from a single pump is supplied to both motors. This ensures that each motor ca generate the same torque, but allowing for differential torque, for example in the case of slippage of one of the wheels, or during cornering when an inner wheel has a lower rotational velocity than an outer wheel.

[0078] In a two wheeled arrangement, as shown in this example, the wheels 161 are positioned substantially beneath the loading region 131, to best support the weight of the conveyor vehicle 100. Whilst only two wheels are shown, this is for the purpose of il lustration and in practice four or more wheels can be used. For example, in the current arrangement, the discharge vehicle 220 would be required to have four wheels as it is not otherwise supported at the discharge end of the vehicle 220.

[0079] The vehicle coupling 140 may have any suitable arrangement but is typically formed from a ball 142 and corresponding socket 1.41, as mentioned above. In this regard, it will be appreciated that each intermediate conveyor vehicle 230 will typically include a socket 141 proximate one end of the conveyor vehicle 100, for coupling to a ball 142 of a first adjacent vehicle 100.2, and a ball 142 proximate an opposing end of the conveyor vehicle 100.1 for coupling to a socket 141 of a second adjacent vehicle. It will also be further appreciated that the loading and discharge vehicles 210, 220 need riot include both of a ball 142 and socket 141 but rather need only include one of these, such as a socket 1 1 on the loading vehicle 210 and a ball on the discharge vehicle 220, or vice versa, in order to connect to adjacent intermediate vehicles 230.

[0080] The ball and socket arrangement 142, 141 define a lateral pivot point between adjacent conveyor vehicles 100, i, 100.2, allowing for relative rotation of the vehicles about an axis A as shown in Figure 1C. In this arrangement, the vehicle couplin 140 is positioned substantially vertically in-line with the loading region 131 of the conveyor belt 130 in use. This ensures that the axis A is substantially co-incident wit the loading region 131 so that the positio of the loading region 131 remains substantially invariant as adjacent conveyor vehicles 100.2, 100.2 turn and the relative angle between the adjacent eonveyor vehicles 1.00.2, 100.2 varies. This ensures that material discharged from one conveyer vehicle 100.1 onto an adjacent conveyor vehicle 100,2 in the transport direction 241, always lands within the loading region 33 1 at approximately the same position on the conveyor belt 130, which in turn reduces the likelihood of material spillage.

[0081] In this particular example, the vehicle coupling 140 is further positioned above the conveyor belt 130 i use. Positioning the vehicle coupling 140 above the conveyer belt 130 reduces the likelihood of material contacting the vehicle coupling 140 which in turn can cause fouling or clogging of the vehicle coupling 140 and in turn affect vehicle steering and turning performance. [0082] A further aspect of this arrangement is that the vehicle coupling 140 is positioned substantially above a mid point between wheels 361 of the conveyor vehicle 100.2. This in turn ensures that the weight of an adjacent conveyor vehicle 100,1 is supported substantiall above the wheels 161 , thereby assisting in balancing the conveyor vehicle 110.2 and evenly distributing the weight throughout the train 200.

[0083] The angle sensor 150 may be of any suitable form that allows the angle between adjacent conveyor vehicles 100.1 , 100.2 to be determined, in one particular example, the angle sensor 150 includes a rotary transducer or other similar sensor mounted to the vehicle coupling 140. in one example, the rotary transducer 150 is provided in the socket 141 , but alternatively the rotary transducer 150 may be mounted in the ball 142 of the vehicle coupling 140. In any event the rotary transducer is then coupled to the corresponding ball 142 or socket 141 of an adjacent conveyor vehicle, for example by coupling to the ball 142 via rotary connector, such as a shaft including at least one or more typically two universal joints. This allows the sensor to detect rotation about the axis A, whilst accommodating changes in the relative pitch and roll of adjacent conveyor vehicles 100.1 , 100.2, without this affecting the measured relative angle. Additionally, this arrangement ensures the transducer is coincident with the pivot axis, unlike in traditional arrangements, thereby ensuring that the relative angle is detected more accurately.

[0084] As mentioned above, at least one of the conveyor vehicles in the conveyor train includes a distance sensor. The distance sensor can be of any suitable form, but typically includes a star wheel or other maker mounted to one of the wheels, with a proximity sensor, such as a magnet or optical sensor, being used to detect spurs of the star wheel, allowing degrees of rotation of the wheel to be measured. This provides an accurate indication of the distance measured, although it will be appreciated that other suitable direct measurement arrangements can be used. The distance sensor can be mounted on any one of the conveyor vehicles in. the train, but is typically mounted on the loading or discharge conveyor vehicle, although this is not essential,

[0085] An example of a controller will now be described with reference to Figure 3. [0086] In this example, the controller includes a processing system 300 which typicall includes at least one electronic processing device, such as a microprocessor 301 , a memory 302, an optional input/output device 303, such as a touch screen, and an external interface 304 interconnected fa a bus 305 as shown. The external interface 304 can be utilised for connecting the processing system 300 to peripheral devices such as communications networks, remote storage or the like, as well as to one or more angle sensors 1.50, rotation sensors 361 and drive and steering systems 160.

[0087] The processing system 300 receives an indication of the relative angle from the angle sensor 150 from each conveyor vehicle, and of the distance travelled from a distance sensor 361 mounted on at least one of the vehicles, for example by receiving digitised signals or the like, and then controls the drive and steering systems 160, in accordance with relative angle and wheel rotation.

[0088] Consequently, the controller 300 operates to use the relative angle and distance travelled to control the drive and steering systems 1 0 to thereby control the steering angle and drive torque of the conveyor vehicle. This avoids the need to use information regarding the steering angle of other conveyor vehicles, reducing the reliance on sensing and simplifying the control processes, making these more reliable. Additionally, this can be performed on the basis of direct measures of inter-car angle and distance travelled, as determined by the angle sensors and the distance sensor, making measurement and hence control more accurate.

[0089] A separate controller 300 may be provided for each conveyor vehicle 300 in the conveyor train 200, with the controllers 300 of different conveyor vehicles 100 being in communication, or acting independentl as required. More typically however, a single master controller is provided for the entire conveyor train 200, with the single master controller 300 controlling each conveyor vehicle 100 as required, This can be performed using slave controllers mounted t each conveyor vehicle, or alternatively by interfacing directly with the distance sensor 361 , the angle sensors 150, and the drive and steering systems 160 on each conveyor car, as shown. [0090] In use, the microprocessor 301 executes instructions which ma be stored in the memory 302 allowing the microprocessor 301 to interpret the signals and generating control signals for the locomotion systems 160, Accordingly, it will be appreciated that the controller may he formed from any electronic processing device such as a microprocessor, microchip processor, logic gate configuration, programmable logic controller (PLC), firmware optionall associated with implementing logic such as an FPGA (Field Programmable Gate Array), or any other electronic device, system or arrangement,

[0091 ] The controller typically receives an indication of relative angles for multiple conveyor vehicl es and for a vehicle heading i a straight direction, reduces the drive torque of the conveyor vehicle i the event that at least one forward conveyor vehicle is turning. This helps ensure that the conveyor vehicle travels at a slightly reduced linear velocity, thereby accounting for the change in linear velocity occurring as the leading conveyor vehicles corner.

[0092] The controller further typically operates by determines a reference relative angle between a leading pair of conveyor vehicles and at one or more reference positions, monitors a distance travelled by at least one conveyor vehicle in the conveyor train and controls the drive torque and steering angle so that the relative angle betwee each other pair of conveyor vehicles is the same as the reference relative angle at each of the one or more reference positions. Thus, the controller simply tracks the inter-car angle betwee the first and second conveyor vehicles in a conveyor train at respective positions, making sure each subsequent pair of conveyor vehicle has the same i nter-ear angle at the same positions.

[0093] An example of operation of the controller to control a conveyor train will now be described with reference to Figures 4 A to 4D.

[0094] For the purpose of this example, the conveyor train includes five conveyor vehicles (also referred to as "cars"), including a loading vehicle 210, three intermediate vehicles 220, a discharge vehicle 230, and six wheel pairs, but it will be appreciated that this is for the purpose of illustration only. In this example a single PLC is coupled to the five angle sensors via Ethernet connections. Data, is tracked by the PLC in a data table, with the data being indexed by a proximity switch mounted on the inside of one of the conveyor vehicle wheels 161. As the wheel rotates the proximity switch detects a flag corresponding to a spur on a star wheel every 50 ram of travel.

[QG95| When tramming in an inbye direction, shown in Figure 4 A and 4C, the loading vehicle 210 is the lead vehicle, steering a lead set of wheels When the loading vehicle 210 turns (say to the right) this will cause a change in the relative angle between the loading vehicle 210 and the first intermediate vehicle 220, 1. The relative angle measured at intermediate vehicle 220.1 is recorded every 50mm of distance travelled. After 8 meters of travel or 160 pulses from the distance sensor, the first intermediate vehicle 220, i is steered so that the angle sensor between the first and second intermediate vehicles 220.1, 220.2 matches the angle recorded.

[0096] Thus, the system records the first inter-car angle IC#01 and the position of the lead car at the start of a turn as the reference position in a data table and index, The steering angle of Axle#Q2 is used to control the inter-car angle IC#02 to the position, whilst Axle#G3 controls IC#03 to position, Axle#04 controls TC#04 to position, etc. This is then repeated as the conveyor train advances.

[0097] Whe tramming in an outbye direction the discharge vehicle 220 is the lead vehicle. Steering the lead set of wheels will turn the discharge vehicle 220, which is typically a four wheel steering vehicle. If turning to the right this will cause a change in the relative angle between the discharge vehicle 220 and the next intermediate vehicle 230,3. The relative angle measured at intermediate vehicle 230,3 is recorded every 50mm of distance travelled. After 8 meters of travel or 160 pulses from the distance sensor the intermediate vehicle 230.3 is steered, until the angle sensor between the intermediate vehicles 220.3, 220.2 matches the angle recorded. In this case, the steering angle of Axle#02 is used to control the inter-car angle IC#01, whilst Axle#03 controls IC#02 and Axle#04 controls 1C#03, etc,

[0098] As shown in Figure 4D, conveyor vehicles travelling in a straight direction may be slowed relative to the lead loading vehicle 210, accounting for the additional distance travelled by the lead loading vehicle while travelling on an arc. The need to slow vehicles can be calculated based on the turning angle, or alternatively based on deviations of a turning angle from an expected amount. So, for example, if the measured inter-car angle is greater than expected, the trailing vehicles are slowed.

[0099] A specific example of the conveyor system is shown in Figures 5A to 5E. In this example, similar reference numerals increased by 400 are used to show similar features to those described with respect to Figures 1 A to ID. These will not therefore be described in any further detail.

[0100] Thus, Figures 5A to 5E show two conveyor vehicles that can be linked together to form a "train'' of conveyor vehicles. The practical limit to the number of conveyor vehicles depends in the particular implementation, but in one example is approximately 30 conveyor vehicles, with each conveyor vehicle typically being between from 4 metres long to 12 metres long. In this regard, it will be appreciated that longer conveyor vehicles would have difficult in negotiating tight bends withi mines, whilst shorter vehicles would be inefficient to use.

[01.01] Accordingly, the above described arrangements provide conveyor vehicles, a train of conveyor vehicles and a controller for one or more conveyor vehicles, which allows a conveyor trai to be formed for transporting material. The apparatus can easi ly be adapted for use in underground mines, such as coals mines, through the use of appropriate systems, such as flame proof engines and electrical systems, FRAS (Fire-Resistant Anti-Static) conveyor belts or the like,

[0102] In one example, the conveyor vehicles are coupled by a vehicle coupling in the form of a ball and coiTesponding socket arrangement that enables movement between cars in terms of pitch, yaw and roll, whilst maintaining accurate relative position between adjacent conveyor vehicles, which is important in ensuring that successive vehicles in the train accurately follow leading vehicles.

[0103] In one example, the conveyor vehicles are able to operate at independent speed as dictated by the geometry of the steering arc through which conveyor vehicles traverse, hi one example, each conveyor vehicle determines its own tramming speed as dictated by the requirement to match the position of other conveyor vehicles, and notably the immediately proceeding conveyor vehicle. As each conveyor vehicle traverses an are, the speed of each conveyor vehicle varies due to the differing geometry of the conveyor vehicles within, the train, which is negotiating turns, floor rolls and pitch changes.

[0104] Typically the relative angle between each conveyor vehicle is directly measured by an angle sensor, such as a rotary transducer attached to the vehicle coupling, via a bendable shaft attached at one end to the preceding car and attached at the other end to the trailin car. Thus, any rotation movement between the conveyo vehicles can be measured directly, enabling a more accurate assessment of the inter-car angle than can be achieved using traditional techniques,

[0105] In one example, the vehicle coupling is positioned to allow for an optimal transfer of material between conveyor vehicles. In this regard, the vehicle coupling is aligned with loading position of the conveyor vehicle, so that material discharged from an up-stream conveyor vehicle wi ll land on the conveyor belt of the recei ving conveyor vehicle in the ideal position, thus minimizing spillage of coal irrespective of the inter-car angle.

[0106] Furthermore, the use of a ball and socket arrangement in combination with the angle sensor allows the accurate geometric location of cars to optimize the conveyor train's overall geometry, while also accurately measuring, tracking and computing such information to allow steering inputs to be computed to allow following cars to accurately track preceding cars with minimal steering inaccuracy,

[0107] Finally, the use of a ball and socket arrangement permits angular displacement in roll, lateral, pitch and rise between cars while maintaining an accurate overall train length, thereby allowing accurate overall train geometry to be maintained,

[0108] Throughout this specification and claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises ^5' ' or "comprising", will be understood to imply the inclusion of a stated integer or group of integers or steps but not the exclusion of any other integer or group of i ntegers.

[0109] Persons skilled in the art will appreciate that numerous variations and modifications will become apparent. All such variations and modifications which become apparent to persons skilled in the art, should be considered to fall within the spirit and scope that the invention broadly appearing before described.