Patent Description:
It is known to provide a combine harvester (hereafter a "harvester") with systems which can vary the height of an axle. One such arrangement is a body levelling system which maintains the body of the harvester level when working on a slope. Such a system is disclosed <CIT> and is operative to vary the height of the body relative to an axle. Vehicles driving public roads may be subject to a limit on total height. For example, a height limit of <NUM> is currently applied in the European Union. To ensure that a harvester can meet this requirement when travelling on a road, it is known to use a body levelling or other axle height adjustment system to lower the axle height so that the total height of the vehicle does not exceed the limit. However, correct positioning of the axle is dependent on wheel size to ensure that body does not contact the wheels. Often harvesters can be fitted with wheels of different sizes as an option. To cater for this, the known axle height adjustment systems require an operator to enter or select the size of wheel fitted to the axel in question. The system will then apply different offsets (or no offset) for axel height adjustment depending on the wheel size data entered or selected. These arrangements work satisfactorily but are subject to the correct wheel size data being entered or selected. In the event that incorrect wheel size data is entered or selected, this could give rise to a potentially dangerous situation.

Systems capable of determining the size of a wheel of a vehicle using a distance sensor mounted to the vehicle are known from <CIT>, <CIT>, and <CIT>.

<CIT> and <CIT> disclose systems and methods capable of evaluating a tread profile of a tyre and/or detecting tyre defects using one or more laser or radar sensors mounted on the vehicle.

It is an objective of the invention to provide a combine harvester having a system for automatically determining the size of a wheel fitted to the combine harvester for use as an input in a system for adjusting axle height.

It is a further objective of the invention to provide a method of automatically determining the size of a wheel fitted to a combine harvester for use as an input to an axle height adjustment system.

In accordance with an aspect of the invention, there is provided a combine harvester according to claim <NUM>. Further optional features of the combine harvester are set out in the claims dependent on claim <NUM>.

In accordance with another aspect of the invention, there is provided a method of operating a combine harvester according to claim <NUM>. Further optional features of the method are set out in claims dependent on claim <NUM>.

Embodiments of the invention will now be described with reference to the accompanying drawings to enable practice of the invention. But to the contrary, the invention includes numerous alternatives, modifications and equivalents falling within the scope of the appended claims as will become apparent from consideration of the following detailed description.

Certain embodiments of a combine harvester having a system for determining the radius of a wheel and methods of determining the radius of a wheel on a combine harvester are disclosed that utilise electronic functions to enable the automatic measuring of wheel size.

As illustrated schematically in <FIG>, a harvester <NUM> in a first embodiment has single wheels <NUM> on a rear axle <NUM> and whilst the front axle <NUM> has dual wheels, with a dual wheel assembly comprising an outer wheel 12a and an inner wheel 12b on either side.

It should be noted that references hereinafter made to certain directions, such as, for example, "front", "rear", "left" and "right", are made as viewed from the rear of a harvester looking forwardly.

<FIG> illustrates schematically an embodiment of system (indicated generally at <NUM>) for measuring/determining the radius of the various wheels of the harvester. It should be appreciated by one having ordinary skill in the art that the wheel radius measuring system <NUM> illustrated in <FIG> is merely an illustrative of example and that some embodiments may include different features (e.g., additional or fewer features).

The wheel radius measuring system <NUM> comprises a respective distance sensor <NUM> mounted on the harvester at a known location relative each of the wheels <NUM> which are to be measured. Each distance sensor <NUM> is positioned so as to be capable of detecting a distance between the sensor (i.e. a known datum fixed relative to the sensor) and an outer circumferential region of the respective wheel <NUM>. The wheels <NUM> in this case are fitted with pneumatic tyres <NUM> which define a tread 24a and the system measures the radius of each wheel at an outer circumferential region of the tyre. The system also comprises an electronic controller or electronic control unit (ECU) <NUM> and a HMI, indicated schematically at <NUM>. The HMI <NUM> includes a display screen visible to an operator of the machine and user input means. The display screen may be a touch screen through which the operator is able to provide inputs and/or other user input means may be provided which could be physically separate from the display screen. Note that there may be additional components in some embodiments, including one or more controllers that cooperate to enable functionality of the wheel radius monitoring system <NUM> and/or additional sensors, or fewer components.

The distance sensors <NUM> each provide an input signal to the ECU <NUM> indicative a detected distance between the sensor and the outer circumferential region of the tyre <NUM> of its respective wheel. Electronic communications among the various components of the system <NUM> may be achieved over a controller area network (CAN) bus or via a communications medium using other standard or proprietary communication protocols (e.g., RS <NUM>, etc.). Communication may be achieved over a wired medium, wireless medium, or a combination of wired and wireless media.

The ECU <NUM> provides the control logic for wheel measuring functionality. The ECU <NUM> may be part of a general control system for the machine.

In one embodiment, the ECU <NUM> comprises one or more processors, such as processor <NUM>, input/output (I/O) interface(s) (in this embodiment the HMI user interface <NUM>), and memory <NUM>, all coupled to one or more data buses. The memory <NUM> may include any one or a combination of volatile memory elements (e.g., random-access memory RAM, such as DRAM, and SRAM, etc.) and non-volatile memory elements (e.g., ROM, hard drive, tape, CDROM, etc.). The memory <NUM> may store a native operating system, one or more native applications, emulation systems, or emulated applications for any of a variety of operating systems and/or emulated hardware platforms, emulated operating systems, etc. In one embodiment, the memory comprises an operating system and wheel radius determining software. It should be appreciated by one having ordinary skill in the art that in some embodiments, additional or fewer software modules (e.g., combined functionality) may be stored in the memory <NUM> or additional memory. In some embodiments, a separate storage device may be coupled to the data bus, such as a persistent memory (e.g., optical, magnetic, and/or semiconductor memory and associated drives).

The processor <NUM> may be embodied as a custom-made or commercially available processor, a central processing unit (CPU) or an auxiliary processor among several processors, a semiconductor based microprocessor (in the form of a microchip), a macro processor, one or more application specific integrated circuits (ASICs), a plurality of suitably configured digital logic gates, and/or other well-known electrical configurations comprising discrete elements both individually and in various combinations to coordinate the overall operation of the controller <NUM>.

The distance sensors <NUM> can be of any suitable type as are well known in the art capable of detecting the distance between the sensor and the outer circumferential region of the wheel to a suitable level of accuracy. In embodiments, the distance sensors <NUM> are ultrasonic or laser distance sensors. In an embodiment, each distance sensor <NUM> is positioned such that an axis of measurement of the sensor is directed toward the outer circumferential region of its respective wheel <NUM>. In an embodiment, the distance sensors are configured to determine distance information between the sensor and their respective tyre <NUM> to a precision of at least ± <NUM>, or to a precision of at least ± <NUM>, or better.

Each distance sensor <NUM> is mounted to a body or other structural component of the harvester at a suitable location that is a known distance from the wheel <NUM> (e.g. a known distance from an axis of rotation of the wheel). In the embodiment illustrated in <FIG>, a distance sensor <NUM> for one of the outer front wheels 12a is shown mounted to a gantry <NUM> which runs above the front wheels. A sensor <NUM> for the other outer wheel and sensors 22a for the inner front wheels could also be mounted to the gantry <NUM>. However, the sensors can be located on any suitable part of the harvester. The system <NUM> may optionally be extended to the rear wheels <NUM> by means of a further sensor 22b for each rear wheel <NUM>.

The outer circumferential surface region of each tyre <NUM> is profiled to define a tread 24a which includes a series of raised tread features in the form of lugs <NUM> arranged in a pattern and separated by grooves <NUM>. This is a typical tread arrangement for tyres on an agricultural mobile machine like a harvester but tread arrangements comprising other types of raised tread features, such as blocks, ribs or the like, separated by grooves are also known. For ease of reference, the term "tread feature" will be used to define any raised feature of a tyre tread including lugs, blocks, ribs and the like, and the term "groove" will be used to define the regions between such tread features.

With reference to <FIG>, the actual distance measured between a distance sensor <NUM> and the outer circumferential region 24a of a tyre will depend on where the measurement is taken, with a minimum distance Dmin being measured at the outer surfaces 44a of the lugs <NUM> and a maximum distance Dmax measured at the base 46a of the grooves <NUM>. The wheel radius measuring system <NUM> is configured to carry out distance measurements to the tyre in two modes:.

Each sensor should be aligned at a known angle relative to the outer circumferential or tread region 24a of its respective tyre <NUM> which permits the tread depth TD measurement. For example, in one embodiment, each sensor <NUM> is aligned at <NUM> degrees to a plane tangential to the outer circumferential surface 24a of the respective tyre in a measurement zone or region. However, other angles are possible and the sensors can be aligned at in the range of <NUM> to <NUM> degrees, or at an angle in the range of <NUM> to <NUM> degrees, or in a range of <NUM> to <NUM> degrees to said plane.

The distance between the sensor <NUM> and the tyre <NUM> is indicative of the radius/diameter of the wheel. This is illustrated in <FIG> which shows how the distance from a sensor to the outer surface 24a of the tyre <NUM> varies between that for a larger wheel 24b and a smaller wheel 24c, the profile 24c of the tyre for the smaller wheel being shown above the profile 24b for the larger wheel. In this embodiment, the larger wheel 24b might be an R38 size wheel and the smaller wheel an R32 size wheel. Since the position of the sensor <NUM> on the mobile machine is known, relative say to the axis of rotation of the wheel, distance information from the sensor <NUM> can be used to calculate the radius/diameter of the wheel. Typically the radius of the wheel <NUM> will be determined from the minimum distance Dmin. However, data obtained in the relative mode of measurement may also be used and/or may be used to confirm correct operation of the system.

Wheel radius data, and/or other wheel size data which can be determined from the measured wheel radius, is advantageously used as an input to at least one other control system on the mobile machine which requires accurate wheel size data. In accordance with the invention, this includes a system which adjusts the height of an axle to which the wheel is mounted and could be a body levelling system as discussed earlier. The wheel radius data can be provided to the other control system automatically without requiring an input from an operator. In an embodiment, the determined wheel radius may be stored to memory where it can be accessed by any control system on the harvester which requires this data. In an embodiment, rather than using the actual measured wheel radius itself as an input, the system is configured to correlate the measured wheel radius to a standard wheel size and to use the standard wheel size, or data relating thereto, as an input to the other control system. In this regard, the system may compare the measured wheel radius with data relating to a range of standard wheels to determine which standard sized wheel is fitted. Wheel size data for a range of standard wheel sizes expected to be used on the harvester can be stored in the memory, for example in a lookup table. With reference to <FIG>, for example, in a machine that can be fitted with either R32 or R38 size wheels, the controller can determine from the measured wheel radius whether the wheel is an R32 or an R38. The controller may store determined wheel size in memory so that the data can be used as an input to another control system which requires this data. This in effect uses the system for measuring wheel radius to automatically determine the wheel size rather than have the user select the wheel size from a menu option.

The term "standard wheel size" should be understood as including commercially available wheel/tyre combinations for the mobile machine.

Where, in accordance with the claimed invention, the harvester has a body levelling or other axel height adjustment system, data from this body levelling/axle height adjustment system may be provided to the controller <NUM> so that corrections for changes in the relative position of a sensor <NUM> and its respective wheel caused by the body levelling or other axel height adjustment system can be made when determining the wheel radius. Alternatively, the controller <NUM> may be configured so that wheel radius measurement is only carried out when the axle levelling/axle height adjustment system is in a known datum configuration or not active.

For the avoidance of doubt, it should be understood that references herein to a wheel should be considered to include a tyre fitted to the wheel unless the context requires otherwise.

Use of a distance sensor <NUM> to measure the radius of a wheel can also be advantageous in providing ground speed data for the harvester. Typically, ground speed is determined using a sensor in the gearbox/drive train of the harvester to detect rotation of a component whose speed of rotation is fixed relative to the speed of rotation of wheels driven from the component.

From this data, the ground speed is calculated or otherwise derived based on an assumed radius (and hence circumference) of the driven wheels. However, if the radius of the driven wheels is measured using a distance sensor <NUM>, 22a, 22b as described above, the actual measured radius of the driven wheels (or the actual circumference calculated from the measured radius) can be used in place of the assumed radius (assumed circumference) to provide more accurate ground speed data.

As a tyre wears, the radius of the wheel will reduce. <FIG> illustrates changes in a typical tread profile as a tyre wears over time, with the minimum distance Dmin increasing and the tread depth TD decreasing. As the tyre wears, the system <NUM> is able to detect changes in the wheel radius so that ground speed data accuracy is maintained.

Where the system determines which of a range of standard wheel sizes is actually fitted, data relating to the dimensions of the standard wheel size may be used instead of the actual measured radius for calculating ground speed. This at least ensures that the ground speed calculation is based on the actual size of wheel fitted to the harvester.

Where the radius of more than one driven wheel is measured by the system <NUM>, an average of the measured wheel radii may be used for the ground speed calculation. Alternative, wheel radial data from only one of the measured wheels can be used. A measured radius of a non-driven wheel or wheels could alternatively be used provided the non-driven wheel is ostensibly the same size as the driven wheels or an offset used if there is a difference between the sizes of the driven and non-driven wheels. This would be less accurate but may still be acceptable.

As noted above with reference to <FIG>, the system <NUM> is capable of detecting tyre wear over time. In an embodiment, the controller <NUM> is configured to monitor the tyre wear by analysing the minimum distance Dmin measured in the absolute mode and/or the tread depth TD measured in the relative mode. Typically, the system will be calibrated or set to a zero (i.e. no wear) setting when a new tyre <NUM> is fitted. This might be achieved by taking initial reference measurements of the minimum distance Dmin and tread depth TD from the new tyre. The system <NUM>, especially the controller <NUM>, monitors subsequent changes in minimum distance Dmin and tread depth TD over time to provide data relating to tyre wear and/or condition. In a simple embodiment, the controller <NUM> is configured to issue a warning that a change of tyre is approaching when the minimum distance Dmin and/or the trade depth TD reaches a pre-determined value as indicated at A in <FIG>. A further warning may be issued that the tyre must be changed when the minimum distance Dmin and/or the trade depth TD reaches a second pre-determined value as indicated at B in <FIG>. However, in a more sophisticated embodiment, the controller <NUM> records data relating to tyre wear over time and is configured to present information regarding the tyre wear status via the HMI, say when requested by an operator input, or which is issued remotely, say via ACM (telemetry), to enable predictive maintenance of the tyres. Information regarding tyre condition status may be forwarded remotely to a dealer, for example. In an embodiment, the controller <NUM> is configured to map tyre wear over the lifecycle of a tyre by logging the changes in the minimum distance Dmin and/or tread depth TD.

In an embodiment, the controller <NUM> also receives data relating to:.

In an embodiment, the controller <NUM> is configured to combine the distance information provided from the sensors <NUM> with the ground speed data and/or the engine usage data to enable the tyre wear to be logged relative to usage of the harvester. It will be appreciated that the system can be configured to record tyre wear data in a range of different ways which can be configured to enable the system to provided tyre wear data in a range of different formats.

In the embodiment illustrated in <FIG>, a tyre wear sensor <NUM> is provided for each of the wheels. However, the system <NUM> could be limited to only one or some of the wheels. For example, the system may be arranged to only measure the radius of one or some of the front wheels.

It should also be appreciated that the system <NUM> can be adapted for use on harvesters having single wheels on the front axle.

Claim 1:
A combine harvester (<NUM>) having an axle (<NUM>, <NUM>) to which a wheel (<NUM>) is mounted, and a control system arranged for adjusting the height of the axle (<NUM>, <NUM>) including at least one controller (<NUM>);
whereby the combine harvester further comprises a system (<NUM>) for determining the radius of the wheel (<NUM>), the system (<NUM>) for determining the radius of the wheel (<NUM>) comprising a distance sensor (<NUM>) mounted to the combine harvester, the distance sensor being in communication with the at least one controller (<NUM>) and configured to detect distance information relating to a distance between the sensor or a known datum and an outer circumferential surface region of the wheel, the at least one controller (<NUM>) configured to receive the distance information from the distance sensor and to determine the radius of the wheel in dependence on the distance information; and the combine harvester being configured such that the data regarding the wheel radius is used as an input to the control system (<NUM>) arranged for adjusting the height of the axle (<NUM>, <NUM>) to which the wheel (<NUM>) is fitted.