METHOD FOR AUTOMATING AN AGRICULTURAL WORK TASK

Abstract

A method for automating an agricultural work task includes specifying one or more site-specific target values or weighting factors with respect to process-related or agronomic quality criteria via an interface module according to which the work task is to be executed by the soil cultivation implement. The method includes converting the target values or weighting factors in an optimization module into process control variables representing working or operating parameters of the soil cultivation implement, and adjusting the process control variables in a stabilization module by activating positioning or operating units of the soil cultivation implement or the agricultural tractor. In the converting step, feedback data is included with respect to a status of a field surface before or after the cultivation by the implement and with respect to an operating status of the implement or the tractor in order to modify the process control variables.

Claims

1. A method for automating an agricultural work task which is executable by a soil cultivation implement on an agricultural tractor, comprising: specifying one or more site-specific target values or weighting factors with respect to process-related or agronomic quality criteria via an interface module according to which the work task is to be executed by the soil cultivation implement; converting the target values or weighting factors in an optimization module into process control variables representing working or operating parameters of the soil cultivation implement; and adjusting the process control variables in a stabilization module by activating positioning or operating units of the soil cultivation implement or the agricultural tractor; wherein in the converting step, feedback data is included with respect to a status of a field surface before or after the cultivation by the soil cultivation implement and with respect to an operating status of the soil cultivation implement or the agricultural tractor in order to modify the process control variables.

2. The method of claim 1, wherein the site-specific target values or weighting factors are specified based on work preparation.

3. The method of claim 1, further comprising uploading the target values or weighting factors into a memory unit associated with a control unit.

4. The method of claim 1, wherein the process-related or agronomic quality criteria relate to an area performance, process cost, or an agronomic work quality producible by the soil cultivation implement.

5. The method of claim 1, further comprising modifying the site-specific target values or weightings originating from the interface module according to the feedback data.

6. The method of claim 1, further comprising including items of information with respect to a current functional status of the soil cultivation implement in the feedback data.

7. The method of claim 1, further comprising calculating a cost function by the control unit.

8. The method of claim 7, further comprising minimizing the cost function within predetermined limits of the agronomic quality criteria by the control unit for the modification of the process control variables.

9. The method of claim 8, further comprising incorporating the agronomic quality criteria by the control unit as secondary conditions in the cost function.

10. The method of claim 1, wherein, when an adjustment of the process control variables is not possible due to manipulated variable restrictions, the control range is functionally expanded by the control unit by switching on an additional soil cultivation implement.

11. The method of claim 1, further comprising monitoring the soil cultivation implement by the control unit with respect to an interruption of a material flow resulting from the adjustment of the process control variables.

12. The method of claim 11, further comprising counteracting a recognized imminent or already occurring interruption of the material flow on the part of the control unit by activating positioning or operating units of the soil cultivation implement or the agricultural tractor.

13. The method of claim 12, further comprising stopping the travel of the agricultural tractor by the control unit until the material flow interruption is remedied.

14. The method of claim 1, further comprising calculating a site-specific statement of costs by the control unit on the basis of the calculated cost function.

15. The method of claim 14, further comprising displaying the site-specific statement of costs via a user interface.

16. A method for automating an agricultural work task which is executable by a soil cultivation implement on an agricultural tractor, comprising: specifying one or more site-specific target values or weighting factors with respect to process-related or agronomic quality criteria via an interface module according to which the work task is to be executed by the soil cultivation implement; converting the target values or weighting factors in an optimization module into process control variables representing working or operating parameters of the soil cultivation implement; and adjusting the process control variables in a stabilization module by activating positioning or operating units of the soil cultivation implement or the agricultural tractor; calculating a cost function by the control unit; minimizing the cost function within predetermined limits of the agronomic quality criteria by the control unit for the modification of the process control variables; including items of information with respect to a current functional status of the soil cultivation implement in the feedback data; and incorporating the agronomic quality criteria by the control unit as secondary conditions in the cost function; wherein in the converting step, feedback data is included with respect to a status of a field surface before or after the cultivation by the soil cultivation implement and with respect to an operating status of the soil cultivation implement or the agricultural tractor in order to modify the process control variables.

17. The method of claim 16, wherein the site-specific target values or weighting factors are specified based on work preparation.

18. The method of claim 16, further comprising uploading the target values or weighting factors into a memory unit associated with a control unit.

19. The method of claim 16, wherein the process-related or agronomic quality criteria relate to an area performance, process cost, or an agronomic work quality producible by the soil cultivation implement.

20. A method for automating an agricultural work task which is executable by a soil cultivation implement on an agricultural tractor, comprising: specifying one or more site-specific target values or weighting factors with respect to process-related or agronomic quality criteria via an interface module according to which the work task is to be executed by the soil cultivation implement; converting the target values or weighting factors in an optimization module into process control variables representing working or operating parameters of the soil cultivation implement; adjusting the process control variables in a stabilization module by activating positioning or operating units of the soil cultivation implement or the agricultural tractor; and monitoring the soil cultivation implement by the control unit with respect to an interruption of a material flow resulting from the adjustment of the process control variables; wherein in the converting step, feedback data is included with respect to a status of a field surface before or after the cultivation by the soil cultivation implement and with respect to an operating status of the soil cultivation implement or the agricultural tractor in order to modify the process control variables; wherein, when an adjustment of the process control variables is not possible due to manipulated variable restrictions, the control range is functionally expanded by the control unit by switching on an additional soil cultivation implement.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The above-mentioned aspects of the present disclosure and the manner of obtaining them will become more apparent and the disclosure itself will be better understood by reference to the following description of the embodiments of the disclosure, taken in conjunction with the accompanying drawing, wherein:

[0045] FIG. 1 shows an exemplary embodiment of a device for carrying out the method according to the present disclosure for automating an agricultural work task,

[0046] FIG. 2 shows an exemplary embodiment of the method according to the present disclosure, illustrated as a flow chart, for automating an agricultural work task, and

[0047] FIG. 3 shows a detail view of a subordinate control loop.

[0048] Corresponding reference numerals are used to indicate corresponding parts in the drawings.

DETAILED DESCRIPTION

[0049] The embodiments of the present disclosure described below are not intended to be exhaustive or to limit the disclosure to the precise forms disclosed in the following detailed description. Rather, the embodiments are chosen and described so that others skilled in the art may appreciate and understand the principles and practices of the present disclosure.

[0050] FIG. 1 shows a device comprised by an agricultural vehicle for carrying out the method according to the present disclosure for automating an agricultural work task.

[0051] The agricultural vehicle is, by way of example, an agricultural tractor 10 having a rear three-point power lift 12, on which a soil cultivation implement 14 for basic soil or seedbed cultivation is attached, in the form of a cultivator 16 here having a plurality of tines 20 engaging in soil or a field surface 18. The cultivator 16 is used, on the one hand, for loosening and crumbling the soil and, on the other hand, for incorporating overlaid humus material on the field surface 18. The humus material is typically formed by plant residues of a harvested grain field or corn field. For the case of the grain field shown in FIG. 1, it is accordingly straw overlaid on the field surface 18. Alternatively, however, the cultivator 16 can also be used for cultivating a corn field which has been harvested (by a forage harvester).

[0052] Furthermore, a frontal three-point force lift 22 is provided, on which an additional soil cultivation implement 24 in the form of a mulcher 26 is attached, by which the plant residues lying distributed on the field surface 18 may be pre-pulverized if needed to ensure an improved throughput (material flow) at the cultivator 16.

[0053] Both three-point force lifts 12, 22 may be changed in their lift position on the part of a control unit 28 by activating a respective associated hydraulic lift mechanism 30, 32.

[0054] The control unit 28, which is ultimately an onboard computer, is furthermore connected to a user interface 36 housed in a driver cab 34 of the agricultural tractor 10, which comprises an operating panel 38 and a display unit 40, a data interface 42 for establishing a wireless data exchange connection with a central farm management system 44 or a data cloud 46, a GPS receiver 48 for position determination, an engine controller 50, a memory unit 52, a CAN bus or ISOBUS 54, and camera-based detector mechanism 56.

[0055] In addition, the control unit 28 receives items of information of imaging sensor mechanism 58, 60 which optically acquire the field surface 18 in front of the agricultural tractor 10 (forward-looking sensor mechanism 58) or behind the soil cultivation implement 14 (rear-looking sensor mechanism 60). The imaging sensor mechanism 58, 60 include one or more mono or stereo cameras which operate in the visible or IR wavelength range. To improve the data quality, a combination with further sensor mechanism 62 is provided, in the present case a ground penetrating radar 64 or LiDAR 66.

[0056] The forward-looking sensor mechanism 58 is attached in the roof region 68 of the driver cab 34 of the agricultural tractor 10, so that they are subjected to the least possible extent to a dust development caused during the soil cultivation. In contrast, the rear-looking sensor mechanism 60 is associated with the soil cultivation implement 14 and are fastened there on the rear on a supporting implement structure 70. Ground penetrating radar 64 or LiDAR 66 are located in the region of an underside 72 of the agricultural tractor 10 and are oriented on the field surface 18 located underneath.

[0057] FIG. 2 shows an embodiment of the method according to the present disclosure, illustrated as a flow chart, for automating an agricultural work task. The method may be roughly divided into three modules, which form a cascaded control loop and are functionally stored in the control unit 28 as corresponding software. Specifically, these are an interface module 74, an optimization module 76, and a stabilization module 78. Their function is described in detail hereinafter.

Interface Module

[0058] In a first method step, one or more site-specific target values or weighting factors with respect to process-related or agronomic quality criteria are specified by the control unit 28 via the interface module 74, according to which the work task is to be executed by the soil cultivation implement 14.

[0059] The specification of the site-specific target values or weighting factors is performed here in the scope of work preparation or planning. The site-specific target values or weighting factors are subsequently uploaded into the memory unit 52 associated with the control unit 28 or into the data cloud 46, so that they are retrievable from there when the interface module 74 runs through the control loop.

[0060] Carrying out the work preparation or planning is performed on the part of an operator via the operating panel 38 of the user interface 36 or via the central farm management system 44, which in particular has access to an agronomic database, which contains, inter alia, items of information with respect to course, height profile, and dimensions of the field surface 18 to be cultivated, soil properties, prior management history, future management planning including subsequently planned cultivation steps, technical specifications of the soil cultivation implement 14 used, and up-to-date specifications of external influencing factors such as the (prior, current, or predicted to be expected) weather conditions and the like. In the case of cartographically located items of information, they are related by the control unit 28 to position data provided on the part of the GPS receiver 48.

[0061] In this case, the process-related or agronomic quality criteria relate to an area performance, process costs, or an agronomic work quality producible by the soil cultivation implement 14. The process costs cover the total occurring financial commitment with regard to carrying out the work task, in particular fuel costs and running operating costs including the investment costs resulting from the service life of the machines used, labor costs, and possible rental costs in each case per unit of area to be cultivated.

[0062] The site-specific target values or weighting factors initially specified in the course of the work preparation or planning via the interface module 74 are based in this case on heuristic assumptions with respect to the actual process costs. The heuristic assumptions originate here from the minimum process costs predicted to be expected, while in contrast the target values of the agronomic work quality or the quality criteria representing it are assessed as realistically as possible. The former solely form a starting point for the iterative self-optimization process subsequently executed in the context of the cascaded control loop.

Optimization Module

[0063] In a second method step, the target values or weighting factors specified in the interface module 74 are converted into process control variables representing work or operating parameters of the soil cultivation implement 14 in the optimization module 76 by the control unit 28.

[0064] In addition, on the level of the optimization module 76, the site-specific target values or weightings originating from the interface module 74 are modified in accordance with feedback data related to the field status or operating status.

[0065] The judgment of the status of the field surface 18 represented by the feedback data before or after the cultivation by the soil cultivation implement 14 can take place here using the imaging sensor mechanism 58, 60.

[0066] The feedback data provided by the forward-looking sensor mechanism 58 for the case of a harvested grain field relate to status parameters such as the stubble density (i.e., the number of the grain stubbles per unit of area), the height or length of the stubbles or the straw residues, distribution or mass density of an overlaid straw mat, weed infestation, the degree of a soil compaction, and the course of the stubble rows with respect to the cultivation direction. If it is a corn field which has been harvested (by a forage harvester), in particular the status of the stubbles is also significant, namely for the case that they have been split open or flattened by being driven over by the forage harvester during the harvesting process to combat the corn root worm.

[0067] In contrast, the feedback data obtained by the rear-looking sensor mechanism 60 relate, for the case of a harvested grain field, to status parameters such as the degree of incorporation of the grain residues or the remaining degree of straw coverage, the crumbling of the field surface 18, the degree of subsoil loosening, or the degree of incorporation of weeds. In the case of a harvested corn field, in addition to the degree of incorporation of the corn stubble or the plant residues in general, status parameters such as the degree of pulverization of the corn stubbles can be included.

[0068] Furthermore, a modification of the process control variables as a function of an operating status of the soil cultivation implement 14 or the agricultural tractor 10 is provided. It is derived from items of information of a current fuel consumption of the agricultural tractor 10, a current cultivation speed {dot over (x)}.sub.actual resulting from its driving speed, or a working depth d.sub.actual or d.sub.Mulcher,actual of the soil cultivation implement 14 or 24 sensorially acquired at the associated lifting mechanism 30 or 32. The relevant items of information are available to the control unit 28 on the CAN bus or ISOBUS 54 of the agricultural tractor 10.

[0069] Items of information with respect to a current functional status of the soil cultivation implement 14 are also incorporated into the feedback data. The current functional status can be monitored by using camera-based detector mechanism 56 on the soil cultivation implement 14 or its supporting implement structure 70, wherein these mechanisms recognize on the basis of corresponding image processing or analysis whether harvest residues have collected in the tools of the soil cultivation implement 14 (the tines 20 of the cultivator 16 here) and can result in possible disturbances of the cultivation process. Furthermore, a consideration of the current material flow, i.e., the throughput of harvest residues and field soil per unit of time, is possible in the evaluation of the current functional status. Further details are explained in conjunction with the stabilization module 78 described hereinafter.

Stabilization Module

[0070] In a third method step, the previously possibly modified process control variables are adjusted in the stabilization module 78 by the control unit 28 by activating positioning or operating units of the soil cultivation 14 or the agricultural tractor 10. The positioning or operating units are formed in the present case by the two lifting mechanisms 30, 32 and the engine controller 50.

[0071] The process control variables derived by the optimization module 76 on the basis of a cost function are, in the case of a soil cultivation implement 14 designed as a cultivator 16, work or operating parameters in the form of the working depth d (t.sub.q) and the cultivation speed {dot over (x)}(t.sub.q). They are adjusted in the stabilization module 78 by a P, PI, or PID controller or a Riccati status controller by activating the positioning or operating units 30, 32, 50 of the soil cultivation implement 14 or the agricultural tractor 10: The cultivation speed {dot over (x)}(t.sub.q) is adapted here by corresponding interventions in the engine controller 50 of the agricultural tractor 10, while in contrast the working depth d(t.sub.q) is set by suitably changing the lift position of the rear three-point power lift 12, for which purpose the hydraulic lift mechanism 32 is activated accordingly by the control unit 28.

[0072] The material flow corresponding thereto results here from the product of working width b, working depth d(t.sub.q), and cultivation speed {dot over (x)}(t.sub.q) as

{dot over (m)}(t.sub.q)=d(t.sub.q).Math.b.Math.{dot over (x)}(t.sub.q)).

Self-Optimization Process

[0073] For the purposes of the (self-)optimization of the achievable cultivation efficiency and quality, it is provided that a cost function is calculated and minimized within predetermined limits of the agronomic quality criteria by the control unit 28 for modification of the process control variables.

[0074] The cost function is a relationship of the form

J.sub.overall=λ.sub.1.Math.J.sub.Fuel+λ.sub.2.Math.J.sub.Operation+Σ.sub.k=0.sup.Ml(ϵ.sub.k(t.sub.q)t.sub.q).sub.Work quality,

wherein the dimension J.sub.Fuel reflects the fuel costs and the dimension J.sub.Operation reflects the running operating costs. The two dimensions J.sub.Fuel and J.sub.Operation initially result here from the site-specific target values specified via the interface module 74 with respect to the process costs, wherein they are adapted accordingly in the context of the performed self-optimization. The component

[00003]$\underset{k=0}{\overset{M}{.Math.}}{l\left({ϵ}_k\left(t_q\right),t_q\right)}_{\mathrm{Work}\mathrm{quality}}$

corresponds here to an unequal secondary condition for maintaining the site-specific target values for the agronomic work quality or the quality criteria representing it. ϵ.sub.k represents in this case a status parameter obtained by the forward-looking or rear-looking sensor mechanism 58, 60 and l(ϵ.sub.k(t.sub.q),t.sub.q) represents a penalty term, which models the costs upon infringement of a respective agronomic secondary condition ϵ.sub.k,min≤ϵ.sub.k≤ϵ.sub.k,max to be maintained. The summation takes place here over its total number M, corresponding to the scope of the feedback data.

[0075] In other words, the agronomic quality criteria are incorporated as secondary conditions in the cost function by the control unit 28.

[0076] The coefficient λ.sub.1 or λ.sub.2 forms a weighting factor to be selected for the fuel costs or operating costs, the value of which is empirically specified and can be varied by the operator within given limits. This applies, inter alia, to the case in which the operator places increased value on a cost-saving or fuel-saving performance of the cultivation process.

[0077] The basic concept for the agronomic work quality to be achieved, therefore the quality criteria representing it, is that the operator selects the latter in the context of the work preparation or planning and additionally can assess them by an associated weighting factor q.sub.k. The resulting process costs then result as

l(ϵ.sub.k(t.sub.q),t.sub.q)=Σ.sub.q=0.sup.NΣ.sub.j=0.sup.1q.sub.k[(K.sub.j1+K.sub.j2.Math.ϵ.sub.k(t.sub.q)+K.sub.j3.Math.ϵ.sub.k(t.sub.q).sup.2),

wherein the term associated with the index j=0 forms a lower limit and the term associated with the index j=1 forms an upper limit for a corridor to be maintained with respect to the kth status parameter ϵ.sub.k. Such a corridor can be formed, for example, on the basis of a permissible degree of straw coverage between 0% and 30% or between 30% and 60%. The corridor to be maintained for the status parameter ϵ.sub.k then results in a U-shaped curve or increase of the process costs toward the limits of the corridor.

[0078] The parameters K.sub.j1, K.sub.j2, K.sub.j3 are empirically determined values which represent a deviation of the process costs upon infringement of the predetermined target values for the agronomic work quality. These influence the strictness of the rise of the process costs upon reaching the corridor limits. t.sub.q represents the time which has passed at the discrete point in time q.

[0079] The sum Σ.sub.q=0.sup.N corresponds to the total amount of the process costs for an optimization horizon N, which is typically between a few milliseconds up to 5 seconds. If the time counter t.sub.q is assigned, for example, a time span of 1 second, N=5 would thus apply for an optimization horizon of 5 seconds.

[0080] To illustrate the cost function, reference is again to be made in the following to the example of the degree of straw coverage ϵ.sub.residue∈[0,1] behind the soil cultivation implement 14,

ϵ.sub.residue,min≤ϵ(t.sub.q).sub.residue≤ϵ.sub.residue,max.

[0081] ϵ.sub.residue∈[0,1] mechanism that the degree of straw coverage is in an interval between 0% and 100%.

[0082] The process cost expenditure l(ϵ.sub.residue(t.sub.q),t.sub.q) upon infringement of the secondary condition for ϵ.sub.residue then results as

l(ϵ.sub.residue(t.sub.q),t.sub.q)=Σ.sub.q=0.sup.NΣ.sub.j=0.sup.1q.sub.k[(K.sub.j1+K.sub.j2.Math.ϵ.sub.k(t.sub.q)+K.sub.j3.Math.ϵ.sub.k(t.sub.q))=Σ.sub.q=0.sup.Nq.sub.residue[(K.sub.low,1+K.sub.low,2.Math.ϵ.sub.residue(t.sub.q)+K.sub.low,3.Math.ϵ.sub.residue(t.sub.q).sup.2)+(K.sub.high,1−K.sub.high,2.Math.ϵ.sub.residue(t.sub.q)−K.sub.high,3.Math.ϵ.sub.residue(t.sub.q).sup.2)],

where secondary condition is only active in the range of ϵ.sub.residue(t.sub.q)∈[0, ϵ.sub.residue,c] or. ϵ.sub.residue(t.sub.q∈[ϵ′.sub.residue,c,1]. Out of the described range, costs out of the secondary condition are equal zero. Further

K.sub.low,1+K.sub.low,2.Math.ϵ.sub.residue(t.sub.q)+K.sub.low,3.Math.ϵ.sub.residue(t.sub.q).sup.2≥0∀ϵ.sub.residue(t.sub.q)∈[0,ϵ.sub.residue,c],

K.sub.high,1−K.sub.high,2.Math.ϵ.sub.residue(t.sub.q)−K.sub.high,3.Math.ϵ.sub.residue(t.sub.q).sup.2≥0∀ϵ.sub.residue(t.sub.q)∈[ϵ′.sub.residue,c,1],

wherein ϵ.sub.residue,c or ϵ′.sub.residue,c is in each case a fixed value which is specified by the operator. Depending on the situation and preference of the operator, this corresponds to a degree of straw coverage of 0% or 30% or 30% or 60%, respectively.

[0083] For the fuel costs J.sub.Fuel(t.sub.q), the following applies

J.sub.Fuel(t.sub.q)=Σ.sub.q=0.sup.N|{dot over (f)}.sub.target,t.sub.q−{dot over (f)}.sub.actual,t.sub.q|.sup.2,

wherein the deviation of the actual value {dot over (f)}.sub.actual,t.sub.q from a target value {dot over (f)}.sub.target,t.sub.q of the chronological change of the fuel quantity f specified in the context of the work preparation or planning is calculated and subsequently documented by the control unit 28 to add it to the total fuel costs for the field surface 18 to be cultivated. A relationship of the following form applies here

f=f({dot over (x)}(t.sub.q),M.sub.w(t.sub.q),{umlaut over (x)}(t.sub.q),d(t.sub.q),b,t.sub.q),

because the total fuel quantity f consumed at the time t.sub.q or its time derivative {dot over (f)} may generally be described as a function of the working depth d(t.sub.q), the cultivation speed {dot over (x)}(t.sub.q), the working width b, a resistance torque M.sub.w(t.sub.q) opposing the driving or the soil cultivation, and a driving acceleration {umlaut over (x)}(t.sub.q) of the agricultural tractor 10.

[0084] Correspondingly, the following applies for the running operating costs J.sub.Operation(t.sub.q)

J.sub.Operation(t.sub.q)=Σ.sub.q=0.sup.N|{dot over (x)}.sub.target−{dot over (x)}.sub.actual|.sup.2,

wherein here the deviation of the actual value {dot over (x)}.sub.actual from a target value {dot over (x)}.sub.target of the cultivation speed {dot over (x)}(t.sub.q) specified in the context of the work preparation or planning, in other words the area performance equivalent thereto, is calculated and subsequently documented by the control unit 28 to add it to the total operating costs for the field surface 18 to be cultivated.

[0085] To derive the process control variables, a model-predictive approach is selected, which is based on the abovementioned minimization of the cost function within the optimization horizon N. The model-predictive approach supplies a manipulated variable trajectory of the process control variables which is cost optimized with respect to the optimization horizon, wherein it is updated for each following discrete time. The manipulated variable trajectory associated with the current time q then forms the foundation for the activation of the positioning or operating units of the soil cultivation implement 14 or the agricultural tractor 10 in the stabilization module 78. Alternatively, a static optimization method can also be used instead of model predictive approach.

Split-Range Control

[0086] Of course, working or operating parameters such as the working depth d(t.sub.q) and the cultivation speed {dot over (x)}(t.sub.q) have restrictions. In addition, additional restrictions can be intentionally specified by the operator. As a result, this leads to corresponding manipulated variable restrictions when adjusting the process control variables in the stabilization module 78.

[0087] If a manipulated variable restriction results in particular due to limiting of the working depth d(t.sub.q) specified by the operator,

d.sub.min≤d(t.sub.q)≤d.sub.max,

this is thus additionally taken into consideration in the cost function in the form of a further secondary condition, wherein the secondary condition may be represented, similarly to the formulation of the associated penalty term l(ϵ.sub.k(t.sub.q),t.sub.q) in the form l(d(t.sub.q)). Alternatively, a further cost component J.sub.delta d(t.sub.q.sub.) is also added in the cost function,

J.sub.delta d(t.sub.q.sub.)=Σ.sub.q=0.sup.N|d.sub.target−d(t.sub.q)|.sup.2,

wherein d.sub.target represents a target value specified for the working depth d(t.sub.q) in the context of the work preparation or planning.

[0088] For the case in which an adjustment of the process control variables is not possible due to manipulated variable restrictions, the control range of the control unit 28 is expanded by switching on the mulcher 26.

[0089] During the operation of the cultivator 16, a manipulated variable restriction predominantly results due to its limited usable working depth d(t.sub.q). If a manipulated variable saturation thus occurs, an artificial expansion of the manipulated variable range can be achieved by a split range control (see module “split-range control” 82 in FIG. 3). If the cultivator 16 reaches its maximum possible working depth d(t.sub.q)=d.sub.max, the mulcher 26 is thus switched on, wherein its working depth d.sub.Mulcher is adjusted by the control unit 28 by activating the frontal three-point force lift 22 in such a way that the effect of the manipulated variable restriction caused by the cultivator 16 is compensated for.

Operational Monitoring

[0090] In addition, there is the possibility that the soil cultivation implement 14, more precisely the cultivator 16, is monitored by the control unit 28 with respect to an interruption of a material flow {dot over (m)} resulting from the adjustment of the process control variables. In the normal case, the desired material flow {dot over (m)} is ensured by corresponding adjustment of the process control variables. However, there are also situations in which the cultivator 16 clogs, for example due to excess straw accumulations in its tines 20. Such clogs are predicted by the control unit 28 by monitoring of the material flow {dot over (m)} by the camera-based detector mechanism 56.

[0091] An imminent or already occurring interruption of the material flow {dot over (m)} thus recognized is counteracted on the part of the control unit 28 by activating positioning or operating units 30, 32, 50 of the soil cultivation implement 14 or the agricultural tractor 10. The simplest procedure is to intentionally raise and extend the soil cultivation implement 14 by activating the rear three-point force lift 12 or the associated hydraulic lift mechanism 32 until the clog detaches by itself. This can be performed predictively as soon as the control unit 28 recognizes on the basis of the items of information provided by the camera-based detector mechanism 56 that a threshold value to be maintained for clog-free operation is exceeded. In addition, a mulcher 26 attached in the front region of the agricultural tractor 10 can be included to improve the material flow {dot over (m)} on the cultivator 16 by pulverizing the grain residues.

[0092] The monitoring of the material flow {dot over (m)} is included as a subordinate control loop (see module “anti-plug control” 80 in FIG. 3) in the stabilization module 78 provided for adjusting the process control variables. The material flow {dot over (m)} ({dot over (m)}=b.Math.d(t.sub.q).Math.{dot over (x)}(t.sub.q)) thus sinks due to resistance with growing material accumulation m.sub.stat in the soil cultivation implement 14. The process control variable to be changed is in the case of a cultivator 16 also the working depth d (t.sub.q) here. The control unit 28 reduces the process control variable d(t.sub.q) with increasing extent of the material accumulation m.sub.stat to counteract clogging. At the same time, it attempts to maintain the desired material flow m by increasing the working depth d(t.sub.q). Corresponding specification variables d.sub.{dot over (m)} and d.sub.mstat result therefrom for the control of the material flow {dot over (m)}. The present control processes resulting therefrom are harmonized by the control unit 28 in that the lesser of the two specification variables min[d.sub.{dot over (m)}, d.sub.mstat] is always used for adjusting the process control variable d(t.sub.q). Subsequently, the manipulated variable trajectories refined in the modules “anti-plug control” 80 and “split-range control” 82, which are represented by correspondingly adapted target values d′.sub.target, {dot over (x)}′.sub.target, are adjusted by activating the positioning or operating units 30, 32, 50 of the soil cultivation implement 14 or of the agricultural tractor 10 on the basis of the actual values {dot over (x)}.sub.actual, d.sub.actual, and d.sub.Mulcher,actual (see module “status controller” 84 in FIG. 3).

[0093] So as not to further negatively affect the cultivation process, the travel of the agricultural tractor 10 is optionally stopped by the control unit 28 until the clog-related interruption is remedied. For this purpose, the agricultural tractor 10 can be brought to a standstill ({dot over (x)}(t.sub.q)=0) from a specific threshold value for m.sub.stat.

Display & Documentation

[0094] In addition, a site-specific statement of costs is calculated by the control unit 28 on the basis of the calculated cost function and visualized via the user interface 36 or its display unit 40. More specifically, the actually occurring fuel costs and the achieved area performance including possible deviations from the assumptions made in the work preparation or planning can be displayed to the user upon completion of the cultivation process. The display of the deviations can be performed in a site-specific manner for the purpose of improved process analysis.

[0095] The processing results provided in this way are also transmitted by the control unit 28 to a central farm management system 44 via the data interface 42 to enable comprehensible documentation of the field status at any time.

[0096] While embodiments incorporating the principles of the present disclosure have been disclosed hereinabove, the present disclosure is not limited to the disclosed embodiments. Instead, this application is intended to cover any variations, uses, or adaptations of the disclosure using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this disclosure pertains and which fall within the limits of the appended claims.