EP4222460A1 - Method for determining the weight of a load of a mobile work machine, learning method for a data-based model, and mobile work machine - Google Patents
Method for determining the weight of a load of a mobile work machine, learning method for a data-based model, and mobile work machineInfo
- Publication number
- EP4222460A1 EP4222460A1 EP21786359.6A EP21786359A EP4222460A1 EP 4222460 A1 EP4222460 A1 EP 4222460A1 EP 21786359 A EP21786359 A EP 21786359A EP 4222460 A1 EP4222460 A1 EP 4222460A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- value
- model
- load
- working machine
- mobile working
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000000034 method Methods 0.000 title claims abstract description 38
- 238000012937 correction Methods 0.000 claims abstract description 15
- 238000013528 artificial neural network Methods 0.000 claims abstract description 14
- 238000012549 training Methods 0.000 claims abstract description 10
- 238000004590 computer program Methods 0.000 claims description 5
- 239000012530 fluid Substances 0.000 claims description 4
- 230000001133 acceleration Effects 0.000 claims description 2
- 230000002068 genetic effect Effects 0.000 claims description 2
- 238000009420 retrofitting Methods 0.000 claims description 2
- 238000005259 measurement Methods 0.000 abstract description 4
- 230000006870 function Effects 0.000 description 13
- 238000005303 weighing Methods 0.000 description 8
- 230000005484 gravity Effects 0.000 description 5
- 238000013459 approach Methods 0.000 description 4
- 238000013527 convolutional neural network Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 230000015654 memory Effects 0.000 description 2
- 230000001537 neural effect Effects 0.000 description 2
- 238000005457 optimization Methods 0.000 description 2
- 239000000969 carrier Substances 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 238000005183 dynamical system Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 210000002569 neuron Anatomy 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 239000002689 soil Substances 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01G—WEIGHING
- G01G19/00—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups
- G01G19/08—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups for incorporation in vehicles
- G01G19/083—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups for incorporation in vehicles lift truck scale
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01G—WEIGHING
- G01G23/00—Auxiliary devices for weighing apparatus
- G01G23/01—Testing or calibrating of weighing apparatus
Definitions
- the present invention relates to a method for determining a weight value of a load applied to a work tool of a mobile machine, a method for training a data-based model, in particular in the form of an artificial neural network, which is used to correct a model-based value of such a load is, as well as a computing unit for performing the method and such a mobile machine.
- Mobile work machines such as excavators, wheel loaders, cranes or telehandlers are used in various areas, e.g. to carry out earthmoving tasks, transport or loading.
- mobile working machines have a working tool that can be loaded with a load.
- an excavator has an excavator arm with a bucket into which material such as soil can be placed as a load.
- a method for determining a weight value of a load a method for training a data-based model, and a computing unit for carrying out the method and a mobile working machine with the features of the independent patent claims are proposed.
- Advantageous configurations are the subject of the dependent claims and the following description.
- the invention deals with mobile working machines that have a working tool that can be or is loaded with a load. Estimating the mass or the weight of such a load, which is captured or picked up by a working tool of a mobile working machine, is a function that is offered, for example, by manufacturers of mobile working machines or by retrofitters.
- a model-based weight value of the load is determined from at least one measured value of at least one variable measured variable of the mobile working machine using a physical model or route model of the mobile working machine.
- measured variables include, for example, a pressure in a hydraulic fluid in a hydraulic cylinder used to move the working tool, angles that are characteristic of a position of the working tool, positions that are characteristic of a position of the working tool, and accelerations that are characteristic of a position of the working tool.
- the measured value can first be recorded or measured, e.g. by means of suitable sensors.
- a moment caused by the working tool can then be determined using a physical model of the mobile working machine and values of physical parameters of the mobile working machine.
- dimensions and weights or masses as well as centers of gravity of the individual components of the working tool come into consideration as physical parameters.
- the (model-based) weight value of the load can in turn be determined, taking into account a reference torque when the working tool is unloaded or not provided with a load.
- the current load on the hydraulic cylinder can be determined on the basis of pressures measured in hydraulic cylinders. With known lever ratios, a moment can be calculated from this load, which holds or moves the work tool of the mobile working machine upwards against gravity. If the unladen weights (or unladen masses), the location of the centers of gravity and the inertia values of the work tool of the mobile working machine are known, it can be calculated on the basis of the physical route model what proportion of the measured torque is attributable to the unloaded or empty working tools are not required. If a moment is measured or determined that goes beyond the corresponding, calculated value of the physical system model, it can be assumed that it is caused by a load on the working tool.
- a weight value for the load can be determined.
- a more detailed description of such a physical system model and its use as part of a weighing function can be found, for example, in "Dynamical Systems in Applications, Lodz, Tru, December 11-14, 2017” or "A. Renner, H. Wind, O. Sawodny, Online payload estimation for hydraulically actuated manipulators, Mechatronics, Volume 66, 2020, Article 102322".
- status monitors can be used to identify whether the current dynamics suggest that the physical route model is sufficiently accurate, so that the weight of the load can be estimated. If not, a possibly determined weight value should not be used because it is most likely not accurate enough.
- the weight value of the load which is determined (or estimated) using the approach described, ultimately shows a certain inaccuracy compared to the actual weight value of the load.
- One source of inaccuracies are, for example, model inaccuracies with regard to the physical route model of the mobile work machine. These inaccuracies come, among other things, from physical effects that are not fully represented in the plant model (e.g. friction, wear, etc.) or from elements of work equipment that are not taken into account in the modeling (e.g. attachments such as lamps and hoses). Falsified measurements due to the sensors used (e.g. offsets, noise, drift) also have a negative effect on the estimation result.
- a data-based model or a data-based approach preferably in the form of an artificial neural network, with at least one input value, which includes the at least one measured value, to determine a correction value as the output value in order to use the model-based weight value to correct the load.
- MLP Multilayer Perceptron
- a CNN Convolutional Neural Network
- Other database ized correction methods that can be used within the scope of the invention are, for example, “Gaussian Process Regression” (GPR), "Genetic Programming” (e.g.
- GPTIPS GPTIPS
- LOLIMOT Low-Linear Model Trees
- This therefore corresponds to a data-based correction that provides a more accurate result or a more accurate estimate.
- the mentioned inaccuracies of the physical plant model can be compensated.
- the described approach with the physical model is generally optimized for a limited dynamic state of the work machine and delivers less accurate results outside of this state.
- a data-based correction has the potential to expand the limitation of the dynamic state in such a way that the result can be used for downstream functions, such as stability monitoring, anti-tilt protection or other actions of the mobile work machine.
- information about the corrected, model-based weight value of the load ie also the corrected weight value itself, can be output for a user or machine operator, for example by means of a display on a display means.
- measured values (or signals) as for the physical system model are used as input values for the data-based model.
- measured values of other variable measured variables (or signals) can be used as input values, which are not used for the physical plant model, but which are assigned a (certain) relevance, for example.
- the oil temperature or generally a temperature of a hydraulic fluid—can be used as the input value of the data-based model.
- pressures that are not used to determine the model-based weight value for example, also come into consideration, as do control signals that contain information about a shift in the operating point. As has been shown, the influence of such a temperature on the weighing result is very complex to model using the physical system model.
- the data-based model For training (also referred to as teaching) the data-based model, it is proposed to determine a target value or desired value for an output variable of the data-based model from the model-based weight value of the load and a reference weight value for this.
- the reference weight value can stand for the actual or measured weight value of the load and can be determined, for example, by weighing.
- a suitable target value can thus be determined, for example during training, for a specific load whose actual weight is known, which the data-based model should output if possible when the corresponding input values are fed to it.
- an actual value of the output variable of the data-based model or an (actual) output value is then determined using the data-based model with the at least one input value.
- parameters of the data-based model can then be used - these are, for example, weights that the individual neurons in the artificial neural network, if the data-based model as such is implemented, link - be adjusted.
- the target value and the initial value can be supplied to a cost function, so that the parameters can then be adjusted - as optimally as possible - using an optimization algorithm, for example.
- RMSE Root-Mean-Square Error
- Predicted Correction Value initial value
- target value target value
- RMSE Target Correction Value
- an algorithm can then be used that minimizes the RMSE calculated in the cost function. In the case of an MLP neural network, this is e.g. a gradient method with a suitable extension.
- a computing unit according to the invention for example a control device or a control unit of a mobile work machine, is set up, in particular in terms of programming, to carry out a method according to the invention. This applies to both the procedure for determining the weight value of the load and the procedure for training a data-based model. In both cases, the data-based model can be stored on the computing unit.
- the subject matter of the invention is also a mobile work machine with a work tool that can be loaded with a load, at least one sensor device for detecting at least one variable measured variable, and a computing unit according to the invention.
- various types of mobile work machines come into consideration here, such as excavators, wheel loaders, cranes, telehandlers or forklifts.
- such a computing unit can also be used by way of retrofitting a mobile working machine. It is also conceivable to correspondingly replace or update an existing computing unit that, for example, previously only controlled the weighing function based on the physical model.
- Suitable data carriers for providing the computer program are, in particular, magnetic, optical and electrical memories, such as hard drives, flash memories, EEPROMs, DVDs, etc. It is also possible to download a program via computer networks (Internet, intranet, etc.).
- FIG. 1 shows a preferred embodiment of a mobile work machine according to the invention, with which a method according to the invention can be carried out.
- FIG. 2 schematically shows a sequence of a method according to the invention in a preferred embodiment.
- FIG. 3 schematically shows a sequence of a method according to the invention in a further preferred embodiment.
- FIG. 1 shows a mobile work machine 100 according to the invention in a preferred embodiment, here in the form of an excavator, with which a method according to the invention can be carried out.
- the excavator 100 has a working tool 110 in the form of an excavator arm or working arm, which is movably arranged or fastened to an upper structure 120 as a component of the mobile working machine.
- the superstructure 120 is in turn connected to an undercarriage 130 such that it can rotate about a vertical axis of the excavator, for example.
- the working tool 110 has, for example, two components 111 and 112 that are movably connected to one another, as well as a tool 115 designed as a shovel, in order to pick up material or a load 160 .
- the tool 115 is in turn arranged movably on the component 112.
- the working tool 110 also has a hydraulic cylinder 114 and other hydraulic cylinders, not explicitly designated, by means of which the components mentioned can be moved relative to one another.
- three sensor devices or sensors 121, 122 and 125 are arranged on working tool 110, each on a component of working tool 110, by means of which an assigned angle q>i, q>2 or cps can be determined in each case.
- mobile working machines are usually equipped with sensors or sensor devices for detecting the position of the working tool or for detecting the joint angle. Otherwise, such can also be provided in addition.
- sensors or sensor devices include, for example, inertial sensors or inertial measurement units (IMUs), angle sensors (encoders) and/or displacement sensors, encoders or cable pulls installed in the cylinders.
- the angle q>i indicates an angle between the straight line connecting the joints of component 112 (jib) and the superstructure 120 (or a horizontal line there), the angle q>2 indicates an angle between the straight line connecting the joints of component 111 and of the joints of the component 112 and the angle cps indicates an angle between the joint of the joints of the component 112 and the joint of the joint of the tool 115 and its tip.
- the angle ⁇ PL indicates an angle of attack and is defined, for example, by the opening of the tool 115 in relation to a horizontal H (corresponding to a line between the joint of the tool 115 and its tip).
- Arrows pointing vertically downwards are shown at the centers of gravity of the various components of the working tool 110 and are intended to represent the weight forces or masses of the relevant components. These arrows are unspecified.
- an arrow Gz is also shown, which stands for the weight (or the weight value) of the load 160.
- a moment M results, which acts on the joint on which the component 111 is arranged on the superstructure 120.
- This moment M consists of a reference moment MR, which stands for a moment when the tool is unloaded, and a moment MG, which stands for the moment that results from the loading.
- a counter-torque M' must be applied by the hydraulic system in order to hold the working tool in position. This leads to a force F on the hydraulic cylinder 114 or a pressure P therein.
- the weight value Gz of the load 160 can be estimated using the angle and the pressure.
- a computing unit 150 designed as a control unit or control device is provided, by means of which, for example, measured values of the sensors can be recorded and the working tool can be controlled.
- FIG. 2 shows a sequence of a method according to the invention in a preferred embodiment, according to which a weight value of the load is determined or estimated and then corrected.
- the pressure p as a measured value of a measured variable 200 and the three angles q>i , cpz and cps shown as measured values of measured variables 202 are supplied as input variables to a physical system model 204 of the working tool.
- a model-based weight value G*z is then determined there as an estimated value for the weight of the load, taking into account geometric parameters 206, which include, for example, the aforementioned geometric dimensions and lengths of the components of the working tool.
- the measurement variables 200, 202 mentioned are also used as input variables for a data-based model 210 implemented here as an artificial neural network.
- this artificial neural network 210 also includes a value of a further measured variable 208 as an input variable, which can be, for example, a temperature of a hydraulic fluid used in the hydraulic system of the mobile working machine.
- the artificial neural network 210 then supplies a correction value K as an output variable, with which the model-based weight value G*z is corrected additively, for example, so that the corrected weight value G**z is obtained. This can then be displayed to a user on a display means 212, for example.
- FIG. 3 schematically shows a sequence of a method according to the invention in a further preferred embodiment, according to which the data-based model implemented as an artificial neural network, the use of which was described with reference to FIG. 2, is trained.
- a model-based weight value G*z of the load is determined.
- a reference weight value GZ,R for this, for example a measured weight value of the load
- the correction value should compensate for a difference between the model-based weight value G*z and the reference weight value GZ,R. If the model-based weight value G*z for a specific case (with a specific load and specific position or position of the work tool) is 5% higher than the reference weight value GZ,R, i.e. the actual weight value is estimated too high, the target value Kz is negative and is approximately 5% of the reference weight value GZ,R.
- the target value Kz and the output value K are then fed to a cost function 300, taking into account the parameters 304 within the scope of an optimization algorithm 302—here, in particular, weights in the artificial neural network—are adapted. If, in the above example, the correction value K is initially only about 3% of the reference weight value GZ,R, for example, the parameters can be adjusted in such a way that the correction value becomes higher.
- the artificial neural network 210 can be taught or trained by carrying out this process for different positions of the working tool and different weight values of the loads. This can be done in advance before the first use (as described with reference to FIG. 2), but also repeatedly during operation.
- an artificial neural network can be provided with which a weighing function in a mobile working machine that is based on a physical model can sometimes be significantly improved.
- the underlying physical model could also be simplified without losing accuracy.
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Numerical Control (AREA)
- Operation Control Of Excavators (AREA)
Abstract
Description
Claims
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE102020212490.6A DE102020212490A1 (en) | 2020-10-02 | 2020-10-02 | Method for determining the weight of a load on a mobile working machine, learning method for a data-based model and mobile working machine |
PCT/EP2021/076639 WO2022069467A1 (en) | 2020-10-02 | 2021-09-28 | Method for determining the weight of a load of a mobile work machine, learning method for a data-based model, and mobile work machine |
Publications (1)
Publication Number | Publication Date |
---|---|
EP4222460A1 true EP4222460A1 (en) | 2023-08-09 |
Family
ID=78078191
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP21786359.6A Pending EP4222460A1 (en) | 2020-10-02 | 2021-09-28 | Method for determining the weight of a load of a mobile work machine, learning method for a data-based model, and mobile work machine |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP4222460A1 (en) |
DE (1) | DE102020212490A1 (en) |
WO (1) | WO2022069467A1 (en) |
Families Citing this family (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE102021205407A1 (en) | 2021-05-27 | 2022-12-01 | Robert Bosch Gesellschaft mit beschränkter Haftung | Procedure for load estimation of work machines |
DE102022203960A1 (en) | 2022-04-25 | 2023-10-26 | Robert Bosch Gesellschaft mit beschränkter Haftung | Method for improving the leveling angle control of a work machine |
CN114739493B (en) * | 2022-04-26 | 2024-01-26 | 上海三一重机股份有限公司 | Material weighing method and device in working machine and working machine |
DE102022210216A1 (en) | 2022-09-27 | 2024-03-28 | Robert Bosch Gesellschaft mit beschränkter Haftung | Method for estimating a load carried by a work machine and work machine |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
AU2007242056B2 (en) * | 2006-04-20 | 2012-12-06 | Ezymine Pty Limited | Payload estimation system and method |
US9200432B1 (en) | 2014-06-09 | 2015-12-01 | Caterpillar Inc. | Method and system for estimating payload weight with hydraulic fluid temperature compensation |
CN108291387B (en) * | 2016-11-09 | 2020-11-10 | 株式会社小松制作所 | Work machine and work machine control method |
DE102018126809A1 (en) | 2018-10-26 | 2020-04-30 | Liebherr-France Sas | System and method for determining the mass of a payload moved by an implement |
-
2020
- 2020-10-02 DE DE102020212490.6A patent/DE102020212490A1/en active Pending
-
2021
- 2021-09-28 WO PCT/EP2021/076639 patent/WO2022069467A1/en unknown
- 2021-09-28 EP EP21786359.6A patent/EP4222460A1/en active Pending
Also Published As
Publication number | Publication date |
---|---|
WO2022069467A1 (en) | 2022-04-07 |
DE102020212490A1 (en) | 2022-04-07 |
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