Method and system for determining the compaction state of a crop

Abstract

The invention relates to a method for determining a compaction state (stat_D) of a stored crop (12), the surface (14, 52) of which is driven over by a commercial vehicle (16) for compaction, wherein the compaction state (stat_D) is determined as a function of at least one vehicle parameter (para_f) effective during the drive over. The at least one vehicle parameter (para_f) can contain a traction coefficient (k_tr), a drive slip (s_rad), a traction force (F_tr), and a load (F_la). Furthermore, the invention relates to a system (10) with a control unit (18) for carrying out such a method.

Description

The invention relates to a method and a system for determining a compaction state of a stored crop material, the surface of which is traveled over by a commercial vehicle for compaction.In agriculture, it is known to collect mowed and guarded grass and transport it to a storage location (e.g. silo). The stored grass is preferably used in the form of silage as feed. Careful compaction of the stored crop material is important in order to avoid losses in quality of the feed and also unnecessary storage costs. However, in order to achieve optimum compaction, a relatively complex working operation is required.It is therefore an object of the present invention to improve the efficiency in the compaction of a stored crop.This object is achieved by a method having the features of independent claim 1 and a system having the features of independent claim 11.Further advantageous embodiments of the invention are evident from the dependent claims.According to claim 1, a method for determining a compaction state of a stored crop material is proposed, the surface of which is traveled over by a commercial vehicle for compaction. In this case, the compaction state is determined as a function of one or more vehicle parameters which are effective during the passing over the surface of the crop. At least one of the following parameters is provided as the vehicle parameter:a traction coefficient of the commercial vehicle or of one or more vehicle wheels.a traction slip of the commercial vehicle or of one or more vehicle wheels.a traction force of the utility vehicle or of one or more vehicle wheels.a load force on the commercial vehicle, i.e. in particular a wheel load or axle load.Depending on the physical-mathematical approach of the method, the vehicle parameters can relate to an overall value of the commercial vehicle or to the values of individual vehicle wheels.The compaction of the crop stored (e.g. in a silo) is a constituent of the production process for silage as animal feed. In particular biomass of agricultural areas is used as crop material, preferably grass or the non-fruit fraction of maize, millet or other crop plants.Taking into account at least one of the aforementioned vehicle parameters, a current compaction state of the stored crop can be determined in real time already during the passing over the crop surface. The technical outlay for this is extremely low, since the current values of the vehicle parameters can be made available in a technically simple manner by means of sensors and / or calculation algorithms. In particular, individual or all vehicle parameters can be provided via a system bus (e.g. ISO, CAN) of the utility vehicle. Knowing the current compaction state supports efficient driving operation of the utility vehicle, since the compaction activity can be ended when a desired and precisely determinable compaction state is reached. In other words, the quality, in particular feed quality, of the stored and compacted crop can be improved with a simultaneous increase in efficiency of the compacting activity. This allows high quality animal feed to be produced at lower operating costs. Knowing and monitoring the continuously determinable current compaction state of the stored crop material relieves an operator (e.g. vehicle driver) of the compaction activity and helps him to make decisions for an efficient compaction work. In particular, the operator can decide in real time during the driving operation of the commercial vehicle whether or not sufficient compaction has been achieved. In addition, electronic processing of the respectively determined current compaction state can support an at least partial automation of the compaction activity.The determined compaction state can be represented, for example, by an absolute numerical value or by a percentage value. As percent values, for example 0% for an uncompacted state, 100% for a completely compacted state and values between 0% and 100% for a correspondingly partially compacted state of the crop can be used.In a preferred embodiment, the traction coefficient and / or the traction slip are compared with provided reference data. The compression state to be determined can be derived from the comparison result. In other words, the sought compaction state is determined depending on the comparison result. As a result, vehicle parameters are related to reference data, so that the current compression state can be determined with little technical and algorithm complexity.For example, different reference densities (e.g. in absolute numerical values of a density or in percentage data) are assigned to the reference data, which facilitates a determination of the current compaction state on the stored crop material on the basis of the aforementioned comparison result. The reference data can be designed as specific data for known travel coverings and / or for at least one known type of crop (e.g. grass or silage).The reference data preferably represent a ratio between a reference traction coefficient and a reference traction slip for different travel coverings and / or for different compaction states of at least one type of crop material, in particular of the crop material currently being processed by a compaction activity.The reference data are preferably generated by previous calibration processes (e.g. with respect to different travel coverings and / or different types of stored crop). The reference data can be provided in a suitable technical form, for example in a database or data center for data retrieval.An estimation or determination of the current compaction state of the stored crop is additionally facilitated if the different compaction states of the crop provided as reference data represent at least a fully compacted state (100% compaction) and an uncompacted state (0% compaction) of the crop. This enables a comparison of the current traction coefficient and / or the current traction slip with the two extreme states mentioned above, whereby the current compression state can be estimated or determined quantitatively particularly accurately during the compression activity.The reference data can be provided, for example, as at least one characteristic curve or a data table. In particular, the reference data are provided in the form of a characteristic field. Different characteristic curves can represent different road surfaces. Individual characteristic curves can represent a specific type of crop. Several characteristic curves can also represent different compaction states of the same type of crop. The characteristic curves enable a comfortable support for the operator during the compaction activity, for example if both the current values of the traction coefficient and of the traction slip and the characteristic curve field are visualized in a display unit (e.g. screen). This allows the operator to recognize the current status or the current compaction state during the compaction activity in a simple visual representation. In addition, the progress of the compacting operation can be immediately recognized.The current values of the vehicle parameters during the passing over the crop surface can, as already mentioned, be determined by means of suitable sensors and / or calculation algorithms.The traction slip is preferably determined as a function of the vehicle speed and the speed of a vehicle wheel or a vehicle axle. In this case, the vehicle speed can be detected, for example, by means of a receiver of a position detection system (e.g. GPS), a ground radar or a detected wheel speed of a vehicle wheel on a non-driven vehicle axle. The wheel speed of a vehicle wheel can be detected by means of a speed sensor on this vehicle wheel or on its vehicle axle.The axle load can be detected or calculated by means of suitable sensors (e.g. pressure sensors in the suspension, sensors on the vehicle tires or the vehicle axles). In particular, the axle load is a dynamic axle load which differs from a constant or static axle load on account of the crop surface being traveled over. In the case of a calculation of the axle load, measured variables of the commercial vehicle dynamics (e.g. pitch, roll), front and / or rear ballasting and known static axle loads of the commercial vehicle can be taken into account.Current values of the traction coefficient can be detected, for example, by means of specific sensors on the commercial vehicle. Alternatively, the traction coefficient is determined with particularly low technical complexity by being determined as a function of the axle load and / or the traction force. In particular, the calculation formula may be used to determine the traction coefficient k_tr of a vehicle wheel. Here, F_tr is the traction force mentioned above and F_la is the load force or wheel load of the vehicle wheel under consideration, wherein the wheel load F_la can be derived from a specified axle load or can be detected by means of a load sensor.The traction force F_tr itself may be determined either by at least one sensor (e.g., on a driven vehicle axle) or by calculation. In the case of a calculation, the traction force is preferably determined as a function of at least one of the following variables:a torque of the utility vehicle, e.g. of the drive train or of a vehicle wheel;a radius of a vehicle wheel of the utility vehicle;a frictional force (rolling resistance) of the utility vehicle, for example of a vehicle wheel, which frictional force is opposed to the traction force.In this case, the basic physical relationship can be used as the basis, according to which the traction force or driving force is the resulting force from the propulsion provided by a torque of the drive train and the opposite rolling resistance of the vehicle wheels.In particular, the calculation formula can be used to calculate the traction force of an individual vehicle wheel. Here, F_tr is the traction force, M_rad is the drive torque or torque of the vehicle wheel, R_rad is the radius of the vehicle wheel or tire, and F_ro is the frictional force or the rolling resistance of the vehicle wheel on the driving surface. The drive torque M_rad can be derived from the total drive torque of the drive train or can be detected by means of a torque sensor.Preferably, for determining the current state of compression with even greater accuracy, at least one of the following items of information is additionally taken into account:at least one further item of information relating to the commercial vehicle. These may be various vehicle data (e.g., tire pressure, vehicle speed). The at least one item of information or the vehicle data can be provided, for example, directly via corresponding sensor signals or via a system bus (e.g. ISO, CAN) of the utility vehicle.at least one item of information characterizing the crop material. In this case, it is possible to distinguish between mowed grass and different cereals, for example. The information can also represent a biological state (e.g. fresh or preweighed) of the crop material.a moisture content of the crop material.Advantageously, a compaction state is determined along the surface of the stored crop to be compacted on a plurality of surface sections. As a result, individual surface sections of the crop can be passed over more or less often than other surface sections in a targeted manner in order to achieve a uniform compaction along the surface of the crop very efficiently.The determined compaction state is preferably visualized on a display unit. The determined compaction state can be represented, for example, directly as a concrete numerical value or as a marking or characteristic curve within the provided characteristic curve field of the reference data, which represent specific compaction states and can likewise be visualized. In the case of the aforementioned section compaction states, a visualization of the surface of the crop material divided into surface sections is advantageous, wherein different section compaction states are represented by different colors of the surface sections.The display unit (e.g. screen) can be part of a user interface for inputting, displaying and outputting data or information. The display unit can be arranged inside the commercial vehicle or outside the commercial vehicle can be part of a mobile or portable device, for example.The invention further relates to a system for determining a compaction state of a stored crop material, comprising a utility vehicle for driving over the surface of the stored crop material and comprising a control unit for carrying out the method according to one of claims 1 to 10.The system according to the invention has the above-described advantages of the method according to the invention. The control unit can contain suitable algorithms for determining a compaction state of the stored crop material and crop material. The system allows data to be provided which are directed to a precise desired compaction state of the stored crop. This supports a high-quality feed production (e.g. silage) with simultaneously efficient working use of the commercial vehicle. The current compaction state of the crop material, which can be continuously determined with the method, relieves the vehicle driver and also other workers during the compaction activity. Furthermore, determined values of the compaction state can serve as a realistic database for an automation of an efficient work process during the compaction of the stored crop material.In conjunction with the ascertained current compaction state, the control unit can generate various further data which, during the compaction activity, can assist a person with further information and / or a control of the utility vehicle. For example, by means of specific algorithms of the control unit, a still necessary residual compaction or a desired compaction dependent on the crop (e.g. of the type, biological state, moisture content) can be calculated. Depending on the ascertained current compaction state, the utility vehicle can be controlled by means of the control unit in order to make its working operation even more efficient. Thus, relevant vehicle parameters such as tire pressure, vehicle speed, steering or lane can be controlled by means of the control unit in a desired manner.Suitable commercial vehicles are, in particular, various types of agricultural commercial vehicles (for example tractors, shovel loaders, telescopic loaders). Autonomous vehicles without a vehicle driver or remote-controlled vehicles are also conceivable.In a preferred embodiment, the control unit is integrated in the commercial vehicle. It can be connected there, for example, to a system bus (e.g., ISO, CAN) and / or to other functional units of the utility vehicle. The data exchange possible as a result can support a precise and efficient functionality of the system.The system further preferably has at least one of the following components, which is connected to the control unit via a data connection:a user interface for inputting and / or visualizing data. This allows user-supported data, in particular data originating from the vehicle driver, to be taken into account in a technically simple manner when determining the compression state. In addition, the current compaction state and progress of the compaction process can be visualized, relieving the operator or operator during the compaction operation.a position detection system (e.g. GPS receiver and optionally further components) which is preferably arranged on the agricultural utility vehicle.a data center with data which have been created and / or provided during the execution of the method. As a result, the control unit can efficiently access data which are relevant for the determination of the compaction state and for the monitoring of the compaction progress.a database with reference data representing different reference compaction states of at least the crop material of the current compaction activity. This supports a supply of data material to the control unit for a precise determination of the density of the stored crop material.The invention is explained in more detail below with reference to the attached drawings. Components that correspond or are comparable with respect to their function are identified with the same reference numerals. The following are shown: FIG. 1 is a block diagram of the system according to the invention, FIG. 2 is a block diagram of details of the method according to the invention, FIG. 3 shows a characteristic curve field with a relationship between a traction coefficient and a traction slip, FIG. 4 ashows a schematic top view of a utility vehicle and of a crop to be compacted, FIG. 4 bshows a side view of the utility vehicle and of the crop to be compacted according to the arrow direction IV-B in FIG. 4 a.FIG. 1 shows a system 10 for determining a compaction state stat_D of a stored crop 12, the surface 14 of which is traveled over by an agricultural utility vehicle 16, here in the form of a tractor, for compaction purposes. The determined compression state stat_D is output by output signals S_a of a control unit 18. The output signals may optionally also include a moisture content W of the crop 12 and other data of interest associated with the compaction action.The control unit 18 is preferably integrated in the utility vehicle 16. The utility vehicle 16 is, for example, controlled by a vehicle driver or active automatically as an autonomous vehicle.The utility vehicle 16 and further components of the system 10 are connected to the control unit 18 via a suitable data connection in order to determine the compaction state stat_D and to communicate it in particular visualized to a person (e.g. the vehicle driver).A position detection system 20 (e.g. GPS) and a user interface 22 (e.g. keyboard and display unit 46 for inputting and / or visualizing data) are arranged in or on the commercial vehicle 16 and are each connected to the control unit 18 via a wired data connection 24. The control unit 18 is connected to a data center 28 via a wireless data connection 26. The latter can be constructed on the basis of cloud technology. It can serve as a central data storage and / or data processing center for various agricultural activities of a agricultural host or farm. The data center 28 contains, among other things, various agricultural-related data d_egr. This data d_egr can be generated at least partially, for example, during the execution of the method for determining the compression state stat_D, and can be stored in the data center 28 and / or can be provided by the data center 28 already before and thus also during the execution of the method. For example, the control unit 18 sends various output signals S_a, in particular the current compression state stat_D, to the display unit 46 for a visualization of the compression state stat_D in real time and simultaneously transmits these output signals S_a via the data connection 26 to the data center 28.In addition, a database 30 with reference data d_ref is connected to the control unit 18 via a further wired data connection 24. The reference data d_ref will be explained in more detail with reference to FIG. 3.Taking into account various vehicle parameters para_f, the control unit 18 may determine the compression state stat_D. Various sensors are arranged on the utility vehicle 16 in order to directly record the values of various vehicle parameters para_f during the passing over the surface 14 of the crop 12 or to calculate them in the control unit 18 by means of the generated sensor data d_sen. In this case, the sensor data d_sen of the sensors are transmitted to the control unit 18 via a further wired data connection 24.The aforementioned sensors are arranged in the region of the rear wheels 32 and the front wheels 34. In the exemplary embodiment, the sensors comprise a load sensor 36, a traction slip sensor system 38 and a torque sensor 40.In a further function, the control unit 18 can be used to control the commercial vehicle 16 in dependence on the determined current compaction state stat_D in order to assist its work. Thus, relevant vehicle parameters such as tire pressure, vehicle speed or steering can be controlled by means of the control unit 18.FIG. 2 shows the control unit 18 which receives the sensor data d_sen as input signals S_e and others. The sensor data d_sen is associated with one or both rear wheels 32 and / or one or both front wheels 34.The control unit 18 can receive further information or quantities at at least one additional signal input. These are, for example:at least one further item of information I_f relating to the utility vehicle 16, for example a tire pressure;an item of information I_er characterizing the crop 12;a moisture content W of the crop 12.The aforementioned information or quantities can be retrieved from other data sources or manually entered via the user interface 22, or they can be provided by measurements. Not necessarily all of the aforementioned information or variables need be available for the control unit 18. For example, the moisture content W and the information I_er characterizing the crop 12 are information which is in each case only optionally received by the control unit 18. Furthermore, optionally, other information or variables, not mentioned here, can also be received by the control unit 18.As already mentioned, the compression state stat_D is determined as a function of a plurality of vehicle parameters para_f, in particular a traction coefficient k_tr and a traction slip s_an. In this case, the drive slip s_an can be determined via the drive slip sensor system 38.For the determination or calculation of the traction coefficient k_tr, the following mathematical-physical relationships are preferably taken into account in the control unit 18 or in the algorithms thereof. The traction coefficient k_tr is defined as a quotient, where F_tr is a traction force and F_la is a load force. These two forces can be determined by means of suitable sensors. For example, the load force F_la can be directly determined by means of the load sensor 36.Alternatively, the two aforementioned forces can be calculated by initially detecting other relevant vehicle variables. By way of example, a calculation of the traction force F_tr by means of the formula is mentioned here. M_f is a known torque of the drive train of the utility vehicle 16, R_rad is a known tire radius of the considered vehicle wheel 32, 34 and F_ro is the frictional force (rolling resistance) of the utility vehicle 16 or of the considered vehicle wheel 32, 34 which is opposed to the traction force F_tr. For an assignment of the traction force F_tr to an individual vehicle wheel 32, 34, the torque M_f of the drive train can be replaced in the formula by the torque M_rad of the considered vehicle wheel 32, 34 which can be derived therefrom.Quite generally, the calculations of the vehicle parameters para_f and physical variables can relate to an overall value of the commercial vehicle 16 or to the values of individual vehicle wheels 32, 34, depending on the physical-mathematical approach.FIG. 3 shows, by way of example, reference data d_ref in the form of a characteristic field, the characteristic curves of which represent different reference compaction states or reference compaction degrees of the crop material 12 to be compacted. The lower characteristic curve KL_min represents a completely non-compressed state (D=0%), while the upper characteristic curve KL_max represents a completely compressed state (D=100%) of the crop 12. Between these two characteristic curves KL_min, KL_max, characteristic curves, not shown here too, with other reference compaction states or reference compaction degrees for the same crop material can optionally be provided.The characteristic curve field shows a relationship or a ratio between the traction coefficient k_tr and the drive slip s_an for different reference compaction states of the crop material 12 to be compacted. Optionally, for comparison, in particular in the case of a visualization for a person, further characteristic curves are also contained in the characteristic curve field. These further characteristic curves preferably represent different road surfaces, for example KL-1 (ice), KL-2 (sludge), KL-3 (wet asphalt), KL-4 (dry asphalt).As already mentioned above, during the compression activity, the current traction coefficient k_tr and the current traction slip s_an can be determined sensorially and / or via calculations. This results in a current operating point 42 which, in the exemplary embodiment according to FIG. 3, is located above the characteristic curve KL_min. The control unit 18 can compare the operating point 42 with the reference characteristic curves KL_min, KL_max and derive the current compression state stat_D as a function of the comparison result. As the compacting action increases, the working points move in the direction of the characteristic curve KL_max, which indicates the progress of the compacting action. This progress is indicated in FIG. 3 by the arrow 44.FIGS. 4 aand 4 b show a silo 48, on the base plate 50 of which the crop 12 is mounted. In a surface region 52, material 54 of the crop 12 is to be compacted. With the aid of position data d_pos of the utility vehicle 16, the surface region 52 can be divided into a plurality of surface sections 52- x, for each of which a compaction state stat_D is determined. The position dependent compaction state stat_D can then be sent to the user interface 22 by means of the control unit 18. In this way, the surface 14 to be traveled over, in particular the surface region 52, can be visualized on the display unit 46 in real time with current compaction states stat_D assigned in sections. In this case, different compaction states stat_D can be represented by different colors. For example, uncompacted surface portions 52- xmay be represented by a red color, fully compacted surface portions 52- xmay be represented by a green color, and surface portions 52- xhaving other compaction states or degrees may be represented by corresponding color gradations.

Claims

Method for determining a compaction state (stat_D) of a stored crop (12), the surface (14, 52) of which is traveled over by a commercial vehicle (16) for compaction, wherein the compaction state (stat_D) is determined as a function of at least one of the following vehicle parameters (para_f) which are effective during the travel over: - a traction coefficient (k_tr), - a drive slip (s_an), - a traction force (F_tr), - a load force (F_la).Method according to Claim 1, characterized in that the traction coefficient (k_tr) and / or the traction slip (s_an) is compared with provided reference data (d_ref) and the compression state (stat_D) is determined as a function of the comparison result.Method according to Claim 2, characterized in that the reference data (d_ref) represent different reference compaction states (KL_min, KL_max) of the crop (12).Method according to Claim 3, characterized in that the different reference compaction states (KL_min, KL_max) contain at least 100% compaction and 0% compaction of the crop (12).Method according to one of Claims 2 to 4, characterized in that the reference data (d_ref) are provided as a characteristic field (KL_min, KL_max).Method according to one of the preceding claims, characterized in that the traction coefficient (k_tr) is determined as a function of the load force (F_la) and / or the traction force (F_tr).Method according to Claim 6, characterized in that the traction force (F_tr) is determined as a function of at least one of the following variables: - a torque (M_f, M_rad) of the commercial vehicle (16), - a radius (R_rad) of a vehicle wheel (32, 34) of the commercial vehicle (16), - a frictional force (F_ro) of the commercial vehicle (16) which is opposed to the traction force (F_tr).Method according to one of the preceding claims, characterized in that the compaction state (stat_D) is determined as a function of at least one of the following items of information: - at least one further item of information (I_f) relating to the commercial vehicle (16), - an item of information (I_er) characterizing the crop (12), - a moisture content (W) of the crop (12).Method according to one of the preceding claims, characterized in that a compaction state (stat_D) is determined in each case along the surface (14, 52) of the stored crop (12) which has been traveled over at a plurality of surface sections (52-x).Method according to one of the preceding claims, characterized in that the compaction state (stat_D) determined is visualized on a display unit (46).System (10) for determining a compaction state (stat_D) of a stored crop (12), having a utility vehicle (16) for compacting the stored crop (12) and having a control unit (18) for carrying out the method according to one of Claims 1 to 10.System according to Claim 11, characterized in that the control unit (18) is contained in the utility vehicle (16).System according to claim 11 or 12, characterised in that at least one of the following components is part of the system (10) and is connected to the control unit (18) via a data connection (24, 26): - a user interface (22) for inputting and / or visualizing data, - a position detection system (20), - a data centre (28) with data (d_egr) which have been produced and / or are provided during the execution of the method, - a database (30) with reference data (d_ref) which represent different reference compaction states (KL_min, KL_max) of the crop material (12).

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