AGRICULTURAL SPRAYER CONTROL SYSTEM AND METHOD

Abstract

A controller for an agricultural sprayer machine is configured to receive for each of a plurality of nozzle sets a respective upper pressure limit, a nozzle reference flow, and a nozzle reference pressure. For each one of the plurality of nozzle sets, a speed setpoint is calculated based upon the application rate setpoint, the nozzle reference flow, the nozzle reference pressure, and the product pressure setpoint.

Claims

1. An agricultural sprayer machine, comprising: a fluid delivery network in selective hydraulic communication with a plurality of nozzle groups disposed in a mutually spaced relationship, wherein each nozzle group comprises a plurality of nozzles that can be independently activated, wherein, when activated, a nozzle of the plurality of nozzles is put into hydraulic communication with the fluid delivery network, wherein a nozzle set comprises at least one nozzle from each nozzle group; and an electronic controller configured to: receive an application rate setpoint and a product pressure setpoint; receive for each of a plurality of nozzle sets a respective upper pressure limit, a nozzle reference flow, and a nozzle reference pressure; and calculate a speed setpoint for each one of the plurality of nozzle sets a based upon the application rate setpoint, the nozzle reference flow, the nozzle reference pressure, and the product pressure setpoint.

2. The agricultural sprayer machine of claim 1, wherein the controller is further configured to adapt the speed setpoint in response to a change in the application rate setpoint or the pressure setpoint.

3. The agricultural sprayer machine of claim 1, wherein the controller is further configured to: receive a pressure range; and generate an adapted pressure setpoint from the pressure setpoint when the pressure setpoint resides outside of the pressure range, wherein the adapted pressure setpoint equals one of an upper limit or a lower limit of the pressure range, and wherein the speed setpoint is based upon the adapted pressure setpoint.

4. The agricultural sprayer machine of claim 1, wherein the controller is further configured to control a forward speed of the agricultural sprayer machine based upon the speed setpoints.

5. The agricultural sprayer machine of claim 4, wherein a forward speed of the agricultural sprayer machine is limited at or below the speed setpoint.

6. The agricultural sprayer machine of claim 1, further comprising a user interface device for receiving speed commands from a driver, wherein the controller is configured to control a forward speed of the agricultural sprayer machine in response to received speed commands, wherein a speed command sequentially steps the speed up or down from a first one of the speed setpoints to a second one of the speed setpoints.

7. The agricultural sprayer machine of claim 1, further comprising a display in communication with the controller, wherein an active one of the speed setpoints is displayed together with a sequential next, inactive, speed setpoint which is available for selection by a driver.

8. The agricultural sprayer machine of claim 1, wherein the controller is configured to: receive an application rate setpoint; for each nozzle set an upper pressure limit, a lower pressure limit, a nozzle reference flow, and a nozzle reference pressure; calculate a speed range for each nozzle set, wherein each speed range comprises a lower speed limit and an upper speed limit, receive a forward speed signal; and select one of the nozzle sets based upon the forward speed signal and the speed ranges.

9. The agricultural sprayer machine of claim 1, wherein the controller is configured to receive and store an operating parameter for each one of a plurality of drift reduction classes, wherein the controller is operable to control at least one of a pump, a forward speed, a nozzle selection, and a display based on the operating parameter of a selected one of the plurality of drift reduction classes.

10. The agricultural sprayer machine of claim 1, wherein the controller is further configured to control a display based upon the speed setpoints.

11. The agricultural sprayer machine of claim 10, further comprising a user interface device for receiving speed commands from a driver, wherein the controller is configured to control the forward speed in response to received speed commands.

12. The agricultural sprayer machine of claim 11, wherein the controller is further configured to generate a driver alert in response to receiving a speed command that corresponds to a speed that exceeds the speed setpoint for a currently active nozzle set.

13. A method of controlling an agricultural spraying machine, the method comprising: receiving an application rate setpoint and a product pressure setpoint; receiving for each of a plurality of nozzle sets a respective upper pressure limit, a nozzle reference flow and a nozzle reference pressure; calculating for each one of the plurality of nozzle sets a speed setpoint based upon the application rate setpoint, the nozzle reference flow, the nozzle reference pressure, and the product pressure setpoint.

14. The method of claim 13, further comprising adapting the speed setpoint in response to a change in the application rate setpoint or the upper pressure limit.

15. The method of claim 13, further comprising controlling a forward speed of the agricultural sprayer machine based upon the speed setpoints.

16. The method of claim 15, further comprising receiving a speed command from a driver and controlling the forward speed of the agricultural sprayer machine in response to the received speed command by sequentially stepping the speed up or down from a first one of the speed setpoints to a second one of the speed setpoints.

17. The method of claim 13, further comprising: receiving a lower pressure limit for each of the plurality of nozzle sets; calculating a speed range for each nozzle set, wherein each speed range comprises a lower speed limit and an upper speed limit; sensing a forward speed of the spraying machine; and selecting one of the nozzle sets based upon the forward speed of the spraying machine and the speed ranges.

18. The method of claim 13, further comprising displaying the speed setpoints.

19. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Further advantages will become apparent from reading the following description of specific embodiments in which:

[0035] FIG. 1 is a plan view of a tractor and pull-type sprayer combination suitable for implementation of embodiments disclosed herein;

[0036] FIG. 2 is a diagrammatic view of part of the spraying machine in accordance with an embodiment showing some nozzles connected to the fluid delivery network;

[0037] FIG. 3 is a block diagram of part of a spraying machine in accordance with an embodiment;

[0038] FIG. 4 is functional flow diagram showing various sub-systems of a spraying machine in accordance with some embodiments;

[0039] FIG. 5 is a plot of system pressure against forward speed for a fixed target application rate for three different nozzle combinations (nozzle 21, nozzle 22, and nozzle 21+22);

[0040] FIG. 6 is the same plot shown in FIG. 5, overlaid with nozzle selection and speed setpoints for 50%, 75% and 90% drift reduction conditions;

[0041] FIGS. 7 through 9 each show a screen from the operator console of the spray machine of FIG. 4; and,

[0042] FIG. 10 is a flow chart illustrating a method of operating a sprayer machine in accordance with some embodiments.

DETAILED DESCRIPTION

[0043] While the disclosure will be described in connection with these drawings, there is no intent to limit to the embodiment or embodiments disclosed herein. Although the description identifies or describes specifics of one or more embodiments, such specifics are not necessarily part of every embodiment, nor are all various stated advantages necessarily associated with a single embodiment or all embodiments. On the contrary, the intent is to cover all alternatives, modifications, and equivalents included within the scope of the disclosure as defined by the appended claims. Further, it should be appreciated in the context of the present disclosure that the claims are not necessarily limited to the particular embodiments set out in the description.

[0044] With reference to FIG. 1, an agricultural spraying machine 10 is illustrated in the form of an agricultural tractor 12 and trailed sprayer 14 combination wherein the sprayer 14 is attached to the tractor 12 at a hitch 15 in a known manner. The tractor 12 and sprayer 14 are driven in a generally forward direction (arrow F) through crop fields to apply pesticides or other nutrient-containing solutions to a growing plant or directly on to the ground. The sprayer 14 is of a generally known pull-type construction and includes ground-engaging wheels 16 and a spray boom 18 which extends transversely with respect to the forward direction F.

[0045] It will be appreciated that although a tractor and trailed sprayer combination is illustrated in FIG. 1, embodiments can be implemented in other types of agricultural sprayer machines including mounted sprayers and self-propelled sprayers.

[0046] Although not shown in FIG. 1, the spray boom 18 may comprise a number of boom sections which are foldable into transport position as is well known in the art. It should be appreciated that the spray boom 18 shown in FIG. 1 is not necessarily to scale and is shown in schematic form only. For example, the spray boom 18 may extend up to widths of around 48 meters.

[0047] With reference also to FIG. 2, mounted to the boom 18 are a plurality of nozzle groups 20 disposed in a mutually-spaced relationship at a distance ‘z’. Each nozzle group 20 includes two individually-controllable nozzles 21, 22, wherein the nozzles 21, 22 for each group have the same flow characteristics. In other words, each nozzle group has a first nozzle 21 of a first type and a second nozzle 22 of a second type which is typically different from the first type. The details and control of the nozzles 21, 22 will be described in more detail below.

[0048] Turning back to the sprayer 14, a chemical tank 24 is provided on a frame for the storage of the chemical solution to be applied. A fluid delivery network 26 is represented schematically in FIG. 1, and serves to hydraulically connect the chemical tank 24 with the nozzles 21, 22. Further details of the fluid delivery network 26 will also described in more detail below.

[0049] In the illustrated embodiment, a first electronic control unit (ECU) 28 is located on the tractor 12 and a second ECU 30 is located on the sprayer 14. The ECUs 28, 30 are connected by wired or wireless connection 32 which allows the controllers 28, 30 to communicate according to the ISO standard 11783 ‘ISOBUS’. ISOBUS facilitates a mutual communication between implements and tractors regardless of the OEM and, in this case, enables data collected and generated by sprayer ECU 30 to be communicated to tractor ECU 28.

[0050] Although two ECUs 28, 30 are disclosed in the illustrated embodiment, it should be understood that the control logic described may be carried out on one or both of the tractor 12 and sprayer 14. For example, the control components described may be located on the sprayer 14 alone. It should be understood, therefore, that references to controller 34 hereinafter are in relation to ECU 28, 30 wherein the components and functionality of controller 34 may be located in one of the tractor ECU 28 and sprayer ECU 30 or distributed across both.

[0051] The controller 34 may be embodied as a custom-made or commercially available processor, an auxiliary processor among several processors (although simplicity in component numbers is desirable for AAM), a semi-conductor micro-processor (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 34.

[0052] The controller 34 includes a memory 62 that may include onboard storage devices represented by read-only (ROM) and random-access (RAM) devices (not shown).

[0053] When certain embodiments of the control systems are implemented at least in part as software (including firmware), it should be noted that alternatively or in addition to ROM, the software can be stored on a variety of non-transitory computer-readable medium for use by, or in connection with, a variety of computer-related systems or methods. In the context of this disclosure, a computer-readable medium may comprise an electronic, magnetic, optical, or other physical device or apparatus that may contain or store a computer program (e.g., executable code or instructions) for use by or in connection with a computer-related system or method. The software may be embedded in a variety of computer-readable media for use by, or in connection with, an instruction execution system, apparatus, or device, such as a computer-based system, processor-containing system, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions.

[0054] When certain embodiments of the control systems are implemented at least in part as hardware, such functionality may be implemented with any or a combination of the following technologies, which are all well-known in the art: a discrete logic circuit(s) having logic gates for implementing logic functions upon data signals, an application specific integrated circuit (ASIC) having appropriate combinational logic gates, a programmable gate array(s) (PGA), a field programmable gate array (FPGA), etc.

[0055] Turning to FIG. 2, three nozzle groups 20 each having two nozzles 21, 22 are shown. Although not shown in detail, each nozzle 21, 22 is mounted upon the rigid structure of boom 18 (FIG. 1). It should also be appreciated that a typical sprayer will include perhaps several tens of nozzle groups 20 and that only three are illustrated in FIG. 2 for clarity of explanation. Furthermore, the nozzle groups 20 may comprise more than two nozzles.

[0056] The fluid delivery network 26 includes a fluid supply line 36 which hydraulically connects a variable flow pump 38 to the nozzles 21, 22 located on the boom 18. The pump 38 pressurizes the fluid supply line 36 by pumping chemical solution from tank 24. Pump 38 may be one of various suitable types including roller vein pumps, centrifugal pumps, diaphragm pumps, and axial-piston pumps, by way of example. The output of the pump 38 is controlled by a rate controller 40 which is part of the controller 34 and connected to the pump 38 via a databus 42 and an electronic connection 44.

[0057] Although a databus 42 is shown and described, the various electronic components can be connected directly without the use of a databus without deviating from the scope of the disclosure.

[0058] The volumetric flow through the fluid delivery line 36 is measured by a flowmeter 46. The pressure of the fluid delivery line 36 is measured by a pressure sensor 48. Both the flowmeter 46 and the pressure sensor 48 are in electronic communication with controller 34 via the databus 42.

[0059] It will be appreciated that the fluid control circuit (or part thereof) shown in FIG. 2 is highly simplified and various other components which would typically be included such as a clean water rinse tank, a chemical inductor, return lines, etc., have been excluded for the sake of simple explanation.

[0060] Each nozzle 21, 22 is plumbed in to the fluid delivery line 36 with a respective connection which comprises a respective electrical solenoid valve 52 for selectively activating the nozzle 21, 22. Each solenoid valve 52 is electrically connected to a nozzle controller 50 which is in communication with databus 42 and is embodied in controller 34. The nozzle controller 50 selectively activates and deactivates the independently controllable nozzles 21, 22. In an alternative embodiment the solenoids are replaced with electrical motors.

[0061] The output of each nozzle 21, 22 is proportional in a quadratic relationship to the pressure p in the fluid delivery line 36, wherein a greater pressure leads to a higher output flow and a lower pressure leads to a lower output flow.

[0062] For the sake of explanation, the illustrated embodiment has nozzles 21 having a first flow characteristic and nozzles 22 having a second flow characteristic that is different from the first. It should be understood that the term “flow characteristic” relates generally to the output flow rate of a given nozzle at a reference pressure. It is known in the art that nozzles having different flow characteristics are available so as to meet a desired application rate within a desired pressure range for example. Such nozzle flow characteristics may be identified by a known color-coding system.

[0063] Although shown schematically in FIGS. 1 and 2, it should be appreciated that nozzle groups may be presented in many different ways. For example, the individual nozzles in each group may be arranged in a compact arrangement and having respective connections to the fluid supply line as illustrated. Alternatively, an integrated spray body having a plurality of nozzles may be connected to the fluid supply line by a single connection, wherein the nozzles are selected by a valve and/or by rotating the spray body.

[0064] References to ‘nozzle sets’ hereinafter is intended to refer to one or more nozzles from each of the nozzle groups 20 to include spaced nozzles, or combination of nozzles, of the same type or having the same flow characteristics, along the boom 18. A nozzle set may include a combination of different nozzles (21, 22, or 21+22) from each nozzle group 20 or only single nozzles (21, 22) from each nozzle group 20. The reference number 21′ will refer to a nozzle set comprising all nozzles 21. The reference number 22′ will refer to a nozzle set comprising all nozzles 22. The reference number 21+22′ will refer to a nozzle set comprising a combination of all nozzles 21 and all nozzles 22. The embodiment illustrated in FIGS. 7 through 9 has nozzle groups with four nozzles each resulting in fifteen different nozzle sets (see FIG. 9) which includes the different combinations of nozzles within the group.

[0065] With reference to FIG. 3, the sprayer machine 10 further comprises a speed sensor 54 which senses the forward speed of the machine 10 and communicates this to controller 34 via databus 42. The speed sensor 54 may be a standalone sensor attached to the sprayer 14 or tractor 12 (radar sensor) or may take a ground speed signal from an on-board satellite positioning system.

[0066] The tractor 12 further comprises an operator console 56 which includes a user interface 58 in the form of a touch screen or a keyboard for example, and a display 59. If embodied in a self-propelled sprayer, it should be understood that the user interface and display is located in the cab of such. In another embodiment, the user interface and display are embodied in a smart device which may be in wireless communication (by Bluetooth for example) with the controller 34 and located in the operator cab.

Rate Control

[0067] Turning to aspects of the control functionality of controller 34 and starting with rate control, the rate controller 40 controls the output of the pump 38 to maintain a target flow q to meet the application rate setpoint Q. Calculation of the pump output may be performed with the following values:

TABLE-US-00001 Application rate setpoint Q Actual forward speed v.sub.a Actual product flow q.sub.a Operating width w Nozzle reference pressure of active nozzle set p.sub.x-ref Nozzle reference flow of active nozzle set q.sub.x-ref Product pressure setpoint p.sub.t

[0068] Pump control signals generated by the rate controller 40 may be pulse width modulated.

[0069] The application rate setpoint Q is entered by the operator and stored by the controller 34. FIGS. 7 through 9 each show a screen from respective viewing modes of the operator console 56. FIG. 7 shows a Nozzle Settings screen 64, FIG. 8 shows a Spraying Control Main screen 60, and FIG. 9 shows a Droplet Control screen 65.

[0070] In the embodiment corresponding to the screens shown in FIGS. 7 through 9, it should be appreciated that the example includes an arrangement with nozzle groups having four individual nozzles (labelled ‘Nozzle 1’, etc.) rather than the two nozzles shown in FIGS. 1 and 2. The Spraying Control main screen 60 allows the operator to set the application rate setpoint Q. The arrangement shown includes buttons 60a, 60b for entering the application rate set point Q which, in this example, is shown as being set at 200 I/ha.

[0071] The actual forward speed v.sub.a is generated by the speed sensor 54 or equivalent device. The actual product flow q.sub.a is generated by the flow meter 46. The operating width w (corresponding to the active nozzles) and nozzle spacing z is stored in the memory 62.

[0072] In the Nozzle Settings screen 64, the operator can enter a nozzle reference pressure p.sub.x−ref and nozzle reference flow for each nozzle available in the group. In the example shown, ‘Nozzle 1’ is selected, a reference pressure p.sub.1-ref of 3.0 bar is entered, and a reference flow (at 3 bar) q.sub.1-ref is entered as 0.8 l/min. The reference pressure p.sub.1-ref and reference flow p.sub.1-ref enable the controller 34 to determine a predicted flow rate at a given pressure when Nozzle 1 is selected. The same information is entered for the other available nozzles in the group.

[0073] The Droplet Control screen 65 allows an operator to enter the product pressure set point p.sub.t that represents a target pressure in the fluid delivery line 36.

[0074] Using these constants and variables, the rate controller 40 controls the pump 38 to deliver the correct flow to apply the chemical solution at the target rate Q. It will be appreciated that as the variables change, this affects the control of pump 38. For example, if the target rate setpoint Q is increased, then the pump output (and system pressure p) will be increased in response.

Drift Reduction Settings

[0075] As forward speed v is increased, the required rate q increases and so the output of pump 38 and the operating pressure p is increased. A relationship between system pressure p and forward speed v for different nozzle sets at a constant target rate Q is shown in FIG. 5. A first plot f.sub.21 corresponds to the first nozzle set 21′, a second plot f.sub.22 corresponds to the second nozzle set 22′, and a third plot f.sub.21+22 corresponds to the third nozzle set 21+22′.

[0076] As mentioned in the background section above, drift-reducing technology has led to the introduction of drift reduction classes for nozzles in which marketed nozzles are certified as meeting drift reduction classes, for example 50%-, 75%-, 90%-drift reducing, when operated within specified pressure ranges. By way of example, and with reference to the nozzles 21, 22, example upper pressure limits may be assigned as per Table 1 below.

TABLE-US-00002 TABLE 1 Upper pressure limit per Drift Reduction Class (bar) Nozzle 50% 75% 90% Nozzle 21 7.0 4.0 2.5 Nozzle 22 8.0 6.0 3.0

[0077] A minimum operating pressure may also be assigned to ensure that the output spray is of a sufficient quality. In one embodiment, the entering of a minimum operating pressure per drift reduction class per nozzle is made mandatory for the operator.

[0078] In the illustrated embodiment, the controller 34 receives and stores for each nozzle 21, 22, an upper pressure limit for each of three drift reduction classes as shown above. Also, a lower pressure limit is entered for each of three drift reduction classes for each nozzle.

[0079] The upper pressure limits for each nozzle operating under each drift reduction class can be entered into the controller 34 by the user using the operator console 56 and Nozzle Settings screen 64. Alternatively, the controller 34 may store a lookup table of different nozzles and their corresponding operating parameters for different drift reduction classes, and retrieve the operating parameters based on an identification of the nozzle type.

[0080] The Nozzle Settings screen 64 allows the operator to enter the upper and lower pressure limits p.sub.dr-1 for Nozzle 1. In this example, the operator has entered an upper pressure limit of 3.0 bar for the 75% drift reduction class, and a lower pressure limit of 1.5 bar. The operator can switch from nozzle to nozzle using buttons 66a to 66d shown on the right-hand side of FIG. 7. For each nozzle set the operator can enter upper and lower pressure limits for each drift reduction class.

[0081] In operation, the controller 34 or the operator selects one of the drift reduction classes c.sub.50, c.sub.75, c.sub.90 The controller 34 operates the sprayer 14 to indirectly maintain the operating pressure p between the lower and upper pressure limits of the selected drift reduction class by controlling speed, wherein the speed is controlled according to speed setpoints that are determined based at least in part on the drift reduction pressure limits p.sub.dr. See below for a more detailed explanation of speed setpoints.

[0082] In one embodiment, the controller 34 is configured to select one of the drift reduction classes based upon a location identifier which may be provided by a global position system in conjunction with an application map having a plurality of regions, each region being associated with a specific drift reduction class. In other words, the drift reduction class selected by the controller 34 is determined by the position of the machine 10 in relation to the application map.

[0083] In an alternative, more primitive, embodiment, the pump 38 is controlled to maintain the pressure p below the upper pressure limit of the selected or active drift reduction class. However in a preferred embodiment, the drift reduction parameters p.sub.dr are embedded in the nozzle settings to calculate speed setpoints and speed ranges which will be described in more detail below.

Speed Setpoints

[0084] The controller 34 embodies a speed controller 68 which is operable to generate speed setpoints v.sub.x, which serve to command a forward speed of the sprayer machine 10 or to indicate an optimum forward speed v to the operator to deliver the target rate Q without exceeding the operating parameters of a selected drift reduction class c. Calculation of each speed setpoint associated with a given nozzle set may be performed with the following values:

TABLE-US-00003 Application rate setpoint Q Product pressure setpoint p.sub.t Operating width w Nozzle spacing z Nozzle reference pressure of active nozzle set p.sub.x-ref Nozzle reference flow of active nozzle set q.sub.x-ref Pressure range (max and min) of active nozzle set p.sub.dr-x

[0085] The speed setpoints v.sub.x are calculated for each nozzle set and each drift reduction class. The listed variables and constants are received by the controller 34 as described above in relation to the flow rate control. The upper and lower pressure limits p.sub.dr-x associated with each drift reduction class are entered through the operator console 56 as also described above.

[0086] Although the speed setpoints v.sub.x may serve only as displayed indications of an optimum driving speed v for the selected nozzle set, this disclosure lends itself particularly well to TIM systems wherein the speed setpoints v.sub.x are communicated by ISOBUS link 32 to the tractor controller 28 and serve as speed commands that are dependent upon the selected nozzle set.

[0087] With reference to FIG. 8, the current speed setpoint v.sub.x may be displayed on the Spraying Control Main screen 60 together with the next lowest and next highest speed setpoints v.sub.x−1, v.sub.x+1, which indicate to the operator the next available speed setpoints at the selected drift reduction class. In this TIM-based system, the operator needs simply to request a step up or step down in speed v to change between speed setpoints v.sub.x, which ensures the application rate Q and drift reduction class requirements can be met with the available nozzles.

[0088] Returning to the embodiment of FIG. 2 having first nozzle set 21′, second nozzle set 22′, and third nozzle set 21+22′, the three corresponding pressure-speed plots of FIG. 5 are overlaid with speed setpoints v.sub.x in FIG. 6. As can be seen from FIG. 6, the speed setpoints correspond to the upper pressure limits for the selected nozzle set and drift reduction class as per Table 1 above. Advantageously, this causes the sprayer machine 10 to operate at an appropriate forward speed v to meet the drift reduction parameters p.sub.dr and target rate Q.

[0089] The speed setpoints v.sub.x depend, inter alia, upon the product pressure setpoint p.sub.t and the pressure range for the selected nozzle and the selected drift reduction class. For a selected nozzle set n.sub.x, a selected drift reduction class c.sub.x, and application rate setpoint Q, the speed setpoint v.sub.x corresponds to the product pressure setpoint p.sub.t unless the product pressure setpoint p.sub.t falls outside of the pressure range p.sub.dr-range for the selected drift reduction class and nozzle set. If the product pressure setpoint p.sub.t does fall outside of the pressure range p.sub.dr-range, then the speed setpoint v.sub.x corresponds to the upper or lower pressure limits for the selected drift reduction class c.sub.x and nozzle set n.sub.x. In other words, the product pressure setpoint p.sub.t is trimmed if it falls outside of the pressure range permitted by the selected drift reduction class and nozzle set.

[0090] Returning to FIG. 6, starting with a drift reduction class of 50% (c.sub.50) it can be seen from the upper pressure limit p.sub.dr for nozzle set 21′, is set at 7.0 bar, resulting in a speed setpoint v.sub.1-50 of 9.2 km/h. The corresponding upper pressure limit for nozzle set 22′ is set at 8.0 bar, which gives a speed setpoint v.sub.1-50 of 15.5 km/h. The corresponding upper pressure limit for the third nozzle set 21+22′ is dictated by the nozzle with the lowest upper pressure limit which is nozzle set 21′. As such the corresponding upper pressure limit for the third nozzle set 21+22′ is set at 7.0 bar, resulting in a speed setpoint v.sub.3-50 of 23.6 km/h.

[0091] For the more stringent drift reduction classes, the upper pressure limits for the respective nozzle sets are reduced due to the requirement for a coarser spray quality. At 75% drift reduction, respective speed setpoints v.sub.1-75, v.sub.2-75, v.sub.3-75 of 5.9 km/h, 13.4 km/h, and 17.8 km/h are calculated for the nozzle sets 21′, 22′, and 21+22′.

[0092] For both the 50% and 75% drift reduction classes, a continuous speed range can be achieved between 4.2 km/h to 17.8 km/h wherein it is possible to apply pesticide at the target rate Q (200 I/ha in this example) while meeting the drift reduction requirements. However, speed gaps g.sub.1, g.sub.2, represented by the horizontal lines in FIG. 6 result from no nozzle set being available to deliver the target rate Q at those speeds under the requirements for 90% drift reduction. Over these speed gaps g1, g2, the pesticide is under applied.

[0093] It should be appreciated that the speed setpoints may be adapted in response to a change in the input parameters. For example, if the available nozzle sets are changed then this may accompany a change in upper pressure limits associated with the drift reduction classes. In turn, the speed setpoints would be adapted accordingly.

[0094] The generation and use of speed setpoints v.sub.x facilitates simple control of the sprayer forward speed v and avoids a situation of under applying the pesticide and/or breaching the thresholds associated with drift reduction classes. When implemented in conjunction with TIM functionality, the speed setpoints v.sub.x serve as discreet selectable speeds that deliver an appropriate spray application for the respective nozzle sets available. Although automatic selection of nozzle set may be based upon the measured actual speed v.sub.a (see below), the selection of forward speed v is commanded by an operator, and the forward speed (at least under a TIM arrangement) may be selected from discrete values that correspond to an optimum speed for the nozzle sets available.

[0095] Alternatively, the speed setpoints v.sub.x serve as upper speed limits for selected nozzle sets, wherein the speed setpoint is stepped up or down in response to a change in selected nozzle set upon command of an operator.

[0096] In yet another alternative embodiment, the speed setpoints v.sub.x are displayed as a guide to the driver. In this case the controller 34 is configured to generate a driver alert in the form of an audible alert and/or a visual alert in response to receiving a speed command from the driver that corresponds to a speed that exceeds the displayed speed setpoint. Moreover, a driver alert may be provided in the case of an operator commanding a switch in nozzle set wherein the current speed cannot deliver the application rate Q at the required drift reduction class c.sub.x.

[0097] Although the generation of speed setpoints v.sub.x has been described in relation to a sprayer machine having multiple nozzle sets, a more primitive arrangement having only a single nozzle set may also benefit from the generation of speed setpoints to either command a speed or indicate an optimal driving speed for the various drift reduction classes c.sub.x stored on the controller.

[0098] An embodiment of a method of controlling the sprayer 14 is shown in FIG. 10, wherein the method comprises receiving an application rate setpoint Q, an upper pressure limit p.sub.dr-x a nozzle reference flow q.sub.x−ref, and a nozzle reference pressure p.sub.x−ref, calculating a speed setpoint v.sub.x based upon the application rate setpoint Q, the nozzle reference flow q.sub.x−ref the nozzle reference pressure p.sub.x−ref, and the upper pressure limit p.sub.dr−1 (act 101); and controlling at least one of a forward speed (act 102a) and a display (act 102b) based upon the speed setpoint v.sub.x.

Automatic Nozzle Switching

[0099] As mentioned above, nozzle controller 50 is embedded in controller 34 and serves to selectively activate and deactivate the independently controllable nozzles 21, 22 in an automatic manner. Automatic nozzle selection may be performed with the following values, which are input into nozzle controller 50:

TABLE-US-00004 Actual speed v.sub.a Application rate setpoint Q Product pressure setpoint p.sub.t Operating width w Nozzle spacing z Nozzle reference pressure of each available nozzle set p.sub.x-ref Nozzle reference flow of each available nozzle set q.sub.x-ref Pressure range (max and min) of active nozzle set p.sub.dr-x

[0100] Speed ranges for each available nozzle set are calculated by the nozzle controller 50 and used to select an appropriate nozzle set based on the sensed forward speed v and optionally the selected drift reduction class. The listed variables and constants are received by the controller 34 as described above in relation to the flow rate control. The upper pressure limits p.sub.dr-x associated with each drift reduction class are entered through the operator console 56 as also described above. The actual speed v.sub.a is provided by speed sensor 48 or other suitable means such as a satellite positioning system.

[0101] In contrast to known automatic nozzle switching systems, the nozzle selection and activation is based upon a measured actual forward speed which is referenced against the calculated speed ranges. The measured pressure p and flow rate q are used only for the rate controller.

[0102] The lower and upper speed limits of each speed range v.sub.x−min, v.sub.x−max for each nozzle set preferably correspond to the speed setpoints v.sub.x calculated as described above, wherein the speed ranges for determining nozzle selection reside between the speed setpoints v.sub.x. Although the speed setpoints v.sub.x are calculated based upon reference data and upper pressure limits p.sub.dr relating to the available nozzles and drift reduction classes, the nozzle selection is based on actual forward speed v rather than a sensed system pressure p.

[0103] Like the speed setpoints described above, the speed ranges are adapted in response to the input parameters including application rate setpoint Q.

[0104] In summary, the above-described agricultural sprayer machine and variations thereof embody a number of concepts which can be implemented in isolation or in various combinations, and in a spraying machine, control system, or a method of operating a sprayer machine. The receiving and storing of operating parameters that relate to a plurality of drift reduction classes allows, for example, the control of automatic nozzle switching or speed control, taking into account the requirements for the drift reduction classes. The generation of speed setpoints based on selected nozzles and optionally on drift reduction parameters allows an operator to control a sprayer with the assurance that the speed suits the nozzles and/or the legislative parameters of the task in hand. The use of a measured forward speed to control nozzle selection delivers a responsive operating system.

[0105] From reading the present disclosure, other modifications will be apparent to persons skilled in the art. Such modifications may involve other features which are already known in the field of agricultural sprayers and component parts thereof and which may be used instead of or in addition to features already described herein.