The invention relates to a method for weighing a load in a bucket of a work machine when the bucket is attached in an articulated manner to at least one end of a boom and the bucket is operated by means of a bucket cylinder and the boom is operated by means of a lifting cylinder, wherein, in the method, a calibration is performed and a load weight measurement is performed in the following steps:

- weighing the load in the bucket by measuring pressure levels of the lifting cylinder during loading,

- determining the position of the boom during the weight measurement, and

- correcting the measured pressure level of the lifting cylinder by means of a correction value so as to obtain a corrected weighing result.

The invention also relates to a weighing system for a work machine equipped with a bucket and to a work machine.

The document US 2008319710 Al known in the prior art discloses a load weighing system that can be installed on a work machine and a method in which weighing is based on a measurement of the hydraulic pressure of the lifting cylinders of the boom of the work machine. The pressure measurement permits a calculation of the force acting on the lifting cylinders. This force is determined not only by the load in the bucket but, among other factors, by the position of the boom and the inclination of the work machine. Even if the positions of all moving parts (base machine, boom and bucket) of the work machine are measured and the result is compensated accordingly, one important factor still remains unaccounted for in practice. This factor is the uneven distribution of a load in the bucket. The distribution of the load affects the distance of the centre of gravity of the load from the point of attachment of the lifting cylinders and thus the force affecting the lifting cylinders even when the position of the bucket is the same or has been compensated in the weight measurement. The weighing result thus depends on the location of the centre of gravity of the load in the bucket. This has often been observed on jobs where, for example, the type of material to be loaded and especially the grain size of ground material varies considerably during the job. This leads to situations in which the centre of gravity of the load in the bucket varies and causes significant measurement errors.

Another analogous weighing system is, for example, the Power weighing system manufactured by the Finnish company Tamtron Oy .

The object of the invention is to provide a method for weighing a load in contact with a bucket which is more accurate than the methods of the prior art and which can take into account the effect produced by a non-centrality of the load on the weight measurement. The characteristic features of this invention are indicated in the attached claim 1. A further object of the invention is to provide a system for weighing a load in contact with a bucket which is more accurate than the systems of the prior art and which can take into account the effect produced by a non-centrality of the load on the weight measurement. The characteristic features of this invention are indicated in the attached claim 13. A further object of the invention is to provide a work machine that comprises a weighing system for weighing a load in a bucket which is more accurate than the machines of the prior art. The characteristic features of this invention are indicated in the attached claim 15.

The object of the method according to the invention can be achieved by means of a method for weighing a load in a bucket of a work machine when the bucket is attached in an articulated manner to at least one end of a boom and the bucket is operated by means of a bucket cylinder and the boom is operated by means of a lifting cylinder, wherein, in the method, a calibration, a load weight measurement and a weight measurement correction are performed. The calibration is performed in the following steps in which first pressure levels of the bucket cylinder and lifting cylinder are determined in the different positions of the boom when the bucket is empty and in a central position, position-corrected second pressure levels of the bucket cylinder and lifting cylinder are determined in the different positions of the boom and bucket both when the bucket is empty and when the bucket is loaded with a load with a known centre of gravity in the bucket, and non-central third pressure levels of the bucket cylinder and lifting cylinder are determined in the different positions of the boom and bucket when the bucket is loaded with a non-central load with a known non-central centre of gravity in the bucket. The load weight measurement is performed in the following steps in which the load in the bucket is weighed by measuring fourth pressure levels of the bucket cylinder and lifting cylinder during loading and both the position of the boom and the position of the bucket are determined during the weight measurement. The weight measurement additionally comprises the calculation of a corrected weighing result using the uncorrected weighing result and a calculated non-centrality , wherein the non-centrality is calculated by means of the measured fourth pressure levels and the measured first position data and second position data as well as the first calibration results and second calibration results, which are stored in a memory register.

Advantageously, the corrected weighing result using the uncorrected weighing result and the calculated non-centrality in the following steps in which, based on the first pressure levels, second pressure levels and third pressure levels, a change in the first pressure level attributable to the position of the bucket in the position of the boom and in the position of the bucket is calculated, for both the bucket cylinder and the lifting cylinder, with an empty and with a full bucket, and, based on the first pressure levels, second pressure levels and third pressure levels, a change in the second pressure level attributable to an asymmetrical distribution of the load in the bucket in the position of the boom and in the position of the bucket is calculated, wherein both the bucket cylinder and the lifting cylinder are affected by said change. Furthermore, in the weight measurement, the change in the second pressure level is scaled to the load used in the calibration in order to establish a scaled change in the second pressure level, a first correction value resulting from the position of the bucket is calculated for the pressure level of the lifting cylinder by comparing the changes in the first pressure level with a change in the third pressure level, which can be obtained as the difference between the first pressure level and the second pressure level of the calibration, and a second correction value resulting from the asymmetrical load is calculated for the pressure level of the lifting cylinder by comparing the changes in the scaled second pressure levels of the lifting cylinder and bucket cylinder with one another. Finally, the measured pressure level of the lifting cylinder is corrected using the first correction value and the second correction value in order to obtain a corrected weighing result.

The main idea behind the invention is based on the observation that a non-centrality of a load can be determined by examining the interrelationship between the pressure levels of the bucket cylinder and the lifting cylinder, which changes as a function of the distribution of the load in the bucket, when the relationship between the pressure levels of the bucket cylinder and the lifting cylinder is known for a bucket with a central load in the different positions of the boom and bucket. In an excavator, for example, in which the tip of the bucket points towards the excavator, a load location in the bucket close to the tip will result in the highest bucket cylinder pressure since the load is further away from the point of articulation of the bucket with the transfer boom and, on the other hand, the lowest lifting cylinder pressure since the load is closer to the point of articulation of the lifting boom. Analogously, a load located at the rear of the bucket results in the lowest bucket cylinder pressure and the highest lifting cylinder pressure. In the invention, it is first determined how much pressure the boom and the bucket alone exert on the lifting cylinder and bucket cylinder in different positions, after which it is possible to determine by how much the pressure increases due to a load. It is also determined by how much a pressure level changes when a load is non-central in the bucket. When these variables are known, it is possible to infer from the ratio of the bucket cylinder and lifting cylinder pressures measured in the weight measurement whether the load is non-central and to take this into account in the weight measurement. It is also possible in the weight measurement to also take into account further factors that can result in a need for correction such as, for example, an orientation of the work machine on an inclined surface or a speed of the boom.

In this context, a central position of the bucket is understood to mean a normal position of the bucket in which the bucket lies in the centre of a path of movement between two end positions .

In the method, the same calibration weight can be used at the central point and at a non-central point of the bucket or, conversely, the weight used in the calibration of a non-central point can also be a different (known) weight. The use of different calibration weights allows the central (base) calibration to be performed with the greatest possible load, which can be difficult to position at a desirable non-central position. For the calibration of a non-central position, a lighter calibration weight of smaller dimensions is advantageously employed .

A non-centrality of a load is understood to mean a deviation from the known central position of the load in the bucket, i.e. the distribution of the load in the bucket during the so-called central base calibration. In a non-central calibration, the load is placed at the tip of the bucket, which in practice is often easier than positioning the load non-centrally at the rear of the bucket .

Although the calibration can be performed with a non-central load located at the tip of the bucket, it is also possible by means of a calculation to perform a weight measurement in situations where a non-central load lies closer, relative to the central centre of gravity of the bucket, to the point of articulation of the bucket, in other words on the other side of the central centre of gravity relative to the tip of the bucket. This is due to the fact that the pressure level changes in a linear manner between the measured central centre of gravity and a non-central centre of gravity on either side of the central centre of gravity so that any non-central centre of gravity of a load can be interpolated from the pressure levels of the calibration.

Advantageously, when calculating a change in the first pressure level, the difference between the first pressure levels and the second pressure levels is interpolated to all positions of the boom for both an empty and a full bucket. By means of the interpolation, a calibration of an enormous number of position points is not necessary, as it is instead possible to interpolate the intervals between the position points while still maintaining good accuracy.

Advantageously, when calculating a change in the second pressure level, the third pressure level is interpolated to all distributions of the load in the bucket.

Advantageously, the interpolation is a first-order interpolation, i.e. a linear interpolation. It has been found that the change in pressure is very linear between points.

The first pressure levels can be determined at 4 - 20 measurement points, advantageously 8 - 12 measurement points, of the boom in an operating range of the boom. A sufficient number of measurement points is thereby provided for a computational compensation of measurement errors caused by a non-central load and a bucket position.

Alternatively, the first pressure levels can be established at 3 to 6 measurement points and the intervals between the measurement points are sine interpolated. This allows the number of measurement points to be kept smaller and the calibration to be performed faster. On the other hand, a calculation of the first pressure levels performed by means of sine interpolation is slightly less accurate than a determination that uses a larger number of measurement points.

Advantageously, the second pressure levels and third pressure levels are established during the slowest possible boom movement during which it is possible to perform a weight measurement. An acceleration resulting from movements of the boom and a measurement error attributable thereto are thus minimized and the pressure measurement can be performed at the measurement points without halting the movement of the boom. The slowest possible movement of the boom is understood to mean the lowest possible speed of movement that can be handled by the equipment used for the measurement when said equipment is controlled normally .

Advantageously, fifth pressure levels are determined when the base machine of the work machine is in an inclined position and a third correction value resulting from the position of the base machine is calculated for the pressure level of the lifting cylinder as the difference between the first pressure level and the fifth pressure level. It is thereby possible to take into account, for example, a situation in which the base machine of the work machine is on an inclined surface and causes a measurement error as the centre of gravity of the load moves the horizontally away from the point of articulation of the boom.

According to an embodiment of the method, sixth pressure levels are further determined when the boom is engaged in a lateral movement and a fourth correction value resulting from the lateral movement of the boom is calculated for the pressure level of the lifting cylinder as the difference between the first pressure level and the sixth pressure level. It is thereby possible to eliminate errors attributable to a lateral movement of the boom in the calculation.

According to a further embodiment of the method, seventh pressure levels are determined when the boom is being operated by means of the lifting cylinder and a fifth correction value resulting from the movement of the boom is calculated for the pressure level of the lifting cylinder as the difference between the first pressure level and the seventh pressure level. It thereby possible to render the weight measurement even more reliable . In one embodiment, the work machine is an excavator and the boom comprises both a lifting boom and a transfer boom, and the calibration and the measurement are both performed in all positions of the lifting boom and transfer boom. With excavators, the significance of a position correction and compensation of a non-central load is increased since the bucket and the load therein are on average further away from the point of articulation of the boom with the base machine than is the case, for example, with bucket loaders, which only have a lifting boom at the end of which a bucket is attached in an articulated manner .

According to one embodiment, the second pressure levels and third pressure levels are also established at 4 to 20 measurement points of the boom, advantageously at 8 to 12 measurement points of the boom, in an operating range of the boom. It is thereby possible to further improve the accuracy of a weight measurement of the method according to the invention, as the intervals between the measurement points that have to be interpolated are shorter than in the embodiment in which the second and third pressure levels are only measured in the end positions of the boom.

Advantageously, the measured position values of the boom are continuously compared with position point values of the boom contained in calibration tables established based on the first pressure levels, second pressure levels and third pressure levels specific to the boom, and a pressure value of the lifting cylinder is determined from the calibration table according to the position point values. It is thereby possible to determine a position-corrected lifting cylinder pressure in the relevant position of the boom directly from the calibration table based on the measurement . Alternatively, instead of using calibration tables, it is possible to establish a calibration function by means of a regression formula based on calibration measurements so as to be able calculate a position-corrected lifting cylinder pressure directly without the use of a table.

Advantageously, the corrected weighing result is displayed to a user by means of a graphical user interface. A user can thus utilize the corrected weighing result during loading.

The corrected weighing result can be utilized in the calculation of the total mass of a load.

Advantageously, the steps of the method are performed automatically during a loading carried out by a user.

A calibration step can be carried out in a fully automated manner or in a semi-automated manner in which a user performs the calibration steps according to instructions issued by the user interface while the measurement itself occurs automatically during the calibration steps performed by the user.

The object of a weighing system according to the invention can be achieved by means of a weighing system for a work machine equipped with a bucket, the work machine comprising a body, at least one boom attached in an articulated manner to the body for the suspension of the bucket, a bucket cylinder that operates the bucket and a lifting cylinder that operates the boom, the system comprising a first pressure sensor for measuring a pressure of the lifting cylinder and establishing first pressure data and a second pressure sensor for measuring a pressure of the bucket cylinder and establishing second pressure data. The system further comprises a first position sensor for determining a position of the boom and establishing first position data, a second position sensor for determining a position of the bucket and establishing second position data, a central unit comprising a memory register, a computation unit and software means for performing a weight measurement calculation as well as data transmission means for relaying the first pressure data, second pressure data, first position data and second position data to the central unit. Stored in the memory register in the system are first pressure levels of the bucket cylinder and lifting cylinder in the different positions of the boom when the bucket is empty, second pressure levels in the different positions of the boom and bucket when the bucket is loaded with a load with a known centre of gravity, and third pressure levels in the different positions of the boom and bucket when the bucket is loaded with a non-central load with a known centre of gravity in the bucket. For the calculation of a corrected weighing result, the software means are configured to calculate the corrected weighing result using the uncorrected weighing result and a calculated non-central- ity, the non-centrality being calculated by means of the measured fourth pressure levels and the measured first position data and second position data as well as the first calibration results and second calibration results stored in the memory register .

Advantageously, for the calculation of a corrected weighing result, the software means are configured to automatically calculate, based on the first pressure levels, second pressure levels and third pressure levels, a change in the first pressure level attributable to the bucket position in the position of the boom and in the position of the bucket, for both the bucket cylinder and the lifting cylinder, with an empty and with a full bucket, and to calculate, based on the first pressure levels, second pressure levels and third pressure levels, a change in the second pressure level attributable to an asymmetrical distribution of the load in the bucket in the position of the boom and in the position of the bucket, wherein both the bucket cylinder and the lifting cylinder are affected by said change. The software means are additionally configured to scale the change in the second pressure level to the load used during calibration in order to establish a scaled change in the second pressure level, to calculate a first correction value resulting from the bucket position for the pressure level of the lifting cylinder by comparing the changes in the first pressure level with a change in the third pressure level, which can be obtained as the difference between the first pressure level and the second pressure level of the calibration, and to calculate a second correction value resulting from an asymmetrical load for the pressure level of the lifting cylinder by comparing the changes in the scaled second pressure level of the lifting cylinder and bucket cylinder with one another. The software means are further configured to correct the measured pressure level of the lifting cylinder by means of the first correction value and the second correction value in order to obtain a corrected weighing result.

The method and weighing system according to the invention can be particularly advantageously implemented in an excavator, but also in a wheel loader or in a telehandler as well as in other analogous applications. The burden to be weighed in the application can be located in a bucket at the end of one, two, or even three or more booms attached to one another, each boom having its own actuator, pressure level measurement and position measurement.

Advantageously, the position sensors used in the system are contactless position sensors, and the association of posit ion sensors advantageously comprises at least one gyroscope in order to take into account prolonged accelerations in the measurements of the position sensors. This allows the position measurement to be realized in a reliable manner.

The invention is illustrated in the following in detail with reference to the attached drawings illustrating embodiments of the invention, wherein

Figure 1 illustrates a weighing system according to the invention realized in conjunction with an excavator in a side view,

Figure 2 illustrates elements of the weighing system as a schematic diagram,

Figures 3a and 3b illustrates the problem of weighing a noncentral load in a bucket,

Figure 4 illustrates, in a side view, a calibration step of the method according to the invention in which the boom is in its innermost position and the bucket is in its innermost position,

Figure 5 illustrates, in a side view, a calibration step of the method according to the invention in which the boom is in its innermost position and the bucket is in its outermost position,

Figure 6 illustrates, in a side view, a calibration step of the method according to the invention in which the boom is in its outermost position and the bucket is in its innermost position,

Figure 7 illustrates, in a side view, a calibration step of the method according to the invention in which the boom is in its outermost position and the bucket is in its outermost position,

Figure 8 illustrates the steps of the method according to the invention as a schematic diagram, Figure 9 graphically illustrates tabular data collected in the memory register during the calibration lifts .

In Figure 1, a method and system 10 according to the invention are illustratively depicted by means of an embodiment realized in connection with an excavator 100 acting as the work machine 14. The excavator 100 comprises a base machine 102, a boom 18 attached in an articulated manner to the base machine 102 by means of a first articulated joint 46, the boom 18 in the excavator 100 consisting of a lifting boom 40 and a transfer boom 42, which is attached in an articulated manner to the lifting boom 40 by means of a second articulated joint 44. A bucket 12 is attached in an articulated manner to the end of the transfer boom 42. A lifting cylinder 22 is attached in an articulated manner between the lifting boom 40 and the base machine 102, a transfer cylinder 47 is attached in an articulated manner between the lifting boom 40 and the transfer boom 42, and a bucket cylinder 20 is attached in an articulated manner between the transfer boom 42 and the bucket 12. Advantageously, there are two lifting cylinders arranged in parallel. Although the present disclosure refers to a single lifting cylinder in the following, it is understood that, depending on the application, there are one, two, or more lifting cylinders arranged in parallel in order to provide the necessary lifting force .

The system 10 comprises a first pressure sensor 24 for measuring a pressure of the lifting cylinder 22 and establishing first pressure data pOl and a second pressure sensor 26 for measuring a pressure of the bucket cylinder 20 and establishing second pressure data p2. The system further comprises a first position sensor 28 for determining a position of the boom 18 and establishing first position data al and a second position sensor 30 for determining a position of the bucket 12 and establishing second position data a2. Advantageously, two first pressure sensors are provided in cases where there are two lifting cylinders arranged in parallel. In the case of an excavator, a first position sensor 28 measures a position of the lifting boom 40 while, in addition, a fourth position sensor 56 is employed to measure a position of the transfer boom 42. Advantageously, the system 10 can also comprise a third position sensor 31, which measures a position of the base machine 102 of the excavator 100, i.e. of the whole comprising the body 16, the cabin and the undercarriage of the excavator 100, in order to detect a potential inclination, and establishes third position data a3.

The employed position sensors can be, for example, acceleration sensors and inclination sensors. Advantageously, at least one of the position sensors is a gyroscope or a so-called 3D position sensor, which detects a position even during prolonged accelerations. The acceleration/posit ion sensors can be, for example, the contactless sensors known under the product designation ADIS16209 from the manufacturer Analog Devices Inc. , and the gyroscope used can be, for example, the gyroscope known under the product designation L3GD20HTR from the manufacturer STMicroelectronics International N.V. Advantageously, the sensors use a Kalman filter. The position sensors can provide the position data 100 - 200 times per second, advantageously 130 - 150 times per second, which can also be the frequency for the measurement of the pressure levels.

The system 10 further comprises, as illustrated in Figure 2, a central unit 32 comprising a memory or memory register 34 for storing the aforementioned pressure data and position data, a computation unit 36 for performing a calculation and software means 38 for performing a weight measurement calculation by controlling the computation unit 36. The central unit 32 can be arranged, for example as illustrated in Figure 1, in the body of the base machine 102 of the excavator 100 under the boom 40 in the base frame 50. As illustrated in Figure 2, the central unit 32 collects all measurement data from the pressure sensors and position sensors, and manages all operational calculations. The central unit can be, for example, a Linux- or Android-based PC unit or some other analogous device, which gets the power it needs for operation from the work machine. The system 10 further comprises data transmission means 45 for relaying at least the first pressure data p01, the second pressure data p02, the first position data al and the second position data a2 to the central unit 32. The data transmission means can be, for example, a CAN bus or some other analogous data transmission bus. The pressure sensors can be operated with analogue signals (4 - 20 mA) or the pressure sensors can be connected directly to the CAN bus. The system 10 advantageously also comprises a display unit 52 and associated controls 55 arranged in the cab 54 of the excavator 100 illustrated in Figure 1 for inputting position values and displaying weighing results as well as for further processing.

Advantageously, the system 10 comprises position sensors that measure the position of the base machine 102, lifting boom 40, transfer boom 42 and bucket 12 of the excavator 100. By means of the position sensor 31 of the base machine 102, the central unit 32 can also determine a position and rotational movement of the base frame 50 of the base machine 102 of the excavator 100. When the system is set up after installation, it measures the forces affecting the lifting cylinders in all areas of the path of movement of the boom and stores them in combination with accurate boom position data in the memory register.

In cases where the method according to the invention is implemented in the context of a wheel loader, the system additionally comprises a limit switch installed on the bucket cylinder for an innermost end limit of the bucket. This ensures that the bucket cylinder does not max out during the measurement, i.e. does not reach a mechanical end position.

Figure 3a illustrates a situation in which a load 11 is located close to the tip of the bucket 12. A compensation of the centre of gravity gl is based on the measurement of the pressures of the bucket cylinder 20 and the lifting cylinders 22 of the boom 18 and their interrelationship. In Figure 3a, the location of the centre of gravity gl of the load is designated by the vector F_l, the distance of the centre of gravity gl from the articulated joint 48 of the bucket 12 is indicated by the line segment A and the force affecting the bucket cylinder 20 is indicated by the vector Fs_b. Figure 3b accordingly illustrates a situation in which a load 11 and centre of gravity g2 are located further inwards in the bucket 12, i.e. closer to the articulated joint 48 of the bucket 12.

The torque acting on the bucket 12 and the force affecting the bucket cylinder 20 both increase as the distance A increases. Analogously, the force acting on the lifting cylinder or cylinders 22 of the boom 18 decreases as the distance A increases, since in this case the centre of gravity gl of the load 11 is closer to the point of articulation 46 of the lifting boom 40 and to the lifting cylinders 22 so that the torque affecting the lifting boom 40 is reduced. All this is relevant since the weighing result is established based on the pressure of the lifting cylinder, as in the known prior art.

It is thereby possible to calculate the correction factors Cl and C2 from the ratio between the force of the bucket cylinder 20 and the forces of the lifting cylinders 22, whereby the weighing result is rendered more accurate. In the context of a setup, a series of calibration movements are performed, wherein the system "learns" the effect of a location of the centre of gravity of a known load 11 on the forces affecting the bucket cylinder 20 and the lifting cylinders 22. Advantageously, a user is guided through the performance of the series of calibration movements according to instructions displayed by a user interface advantageously comprised by the system, whereby the system automatically performs pressure level measurements based on measurement data of the position sensors at selected positions or calibration points. The calibration is advantageously performed on an even surface so that a potential inclination of the base machine does not cause measurement errors.

More specifically, in the pressure measurement for the lifting cylinders of the boom, pressure is measured in real time both on the piston side and on the rod side and a pressure difference is calculated between the two, which is corrected by the ratio of the effective rod-side and piston-side surface areas in the cylinder. It is thereby possible to determine the exact force affecting the lifting cylinders. The effective pressure of the bucket cylinder or cylinders is measured analogously. This can also be combined with other measurement data in order to effectively compensate a bias brought about in the lifting cylinder pressures by a non-central load and thereby improve the accuracy of the final measurement result. In the method, also the positions of the boom and bucket are respectively measured in real time. A wheel loader typically only has a lifting boom while an excavator has a transfer boom as well as a lifting boom. Advantageously, the position of an excavator base machine is also measured so as to allow the compensation of any resulting measurement error.

The method according to the invention can be divided into two main steps, wherein the first is a system calibration step 200 and the second is a measurement step 202, which are illustrated in Figure 8. An advantageous mode of realization of the method and its operation in an excavator are described in the following, although a simpler form of the same method can also be employed in wheel loaders and telehandlers in which the boom consists of a single part. During calibration, the system collects data in the memory register on the pressures of the lifting cylinder and bucket cylinder relative to the positions of the boom and bucket. In the context of an excavator 100, the boom 18 consists of a lifting boom 40 and a transfer boom 42, as illustrated in Figures 1 and 3a - 7. The setting of the base level can be roughly divided into three basic parts: capturing base-level pressure curves, i.e. first pressure levels pl, illustrated as step 204 in Figure 8; capturing position compensation curves for the bucket, i.e. second pressure levels p2, in the memory register 34 illustrated in Figure 2, illustrated as step 206; and capturing the effect of a non-centrality of the load, or third pressure levels p3, in the memory register 34, illustrated as step 208.

When capturing the base-level pressure curves in step 204, a desirable range of the boom is first plotted. In this case, range advantageously means the range of the path of movement of the boom within which it is desirable that a weight measurement of a load should be possible. In the case of an excavator, a desirable number of position points, 4 - 20, advantageously 8 - 12, are plotted for the lifting boom in ascending order starting at the bottom and moving upwards. Points are plotted, for example, at intervals of 10 - 15 angular degrees and stored by the system in a table LiftAngleBins [LiftP] in the memory register of the central unit. A desirable range of the transfer boom is then plotted, starting from the innermost desirable position of the transfer boom and moving outwards, analogously to the lifting boom. The positions of the transfer boom are plotted in a table ArmAngleBins [ArmP] . In this context, reference to the capture or storage of values is invariably understood to mean the storage of values in a memory register of the central unit unless otherwise indicated.

After the position points of the booms have been plotted, base calibration lifts are carried out from the bottom upwards at a slow speed in each plotted position of the transfer boom or bucket arm. This occurs first with an empty bucket and subsequently with a full load while the bucket is in the so- called normal position or 0 position. The pressure measurements measured for the lifting cylinders during the lifts with an empty bucket are stored in a table ZeroMapPressure [ArmP] [LiftP] with the transfer boom positions as row indices and the lifting boom positions as column indices. Corresponding measurements carried out during lifts with a full load are stored in a table LoadMapPres sure [ArmP] [LiftP] . During the lifts, pressure measurements for the bucket cylinder are additionally stored in a table Bucket ZeroPress [ArmP] [LiftP] for an empty bucket and accordingly in a table BucketLoadPress [ArmP] [LiftP] for a full load. During the base calibration lifts, the bucket positions assumed during the lifts are additionally stored in a table BucketNPos [ArmP] [LiftP] . These are the so-called normal positions of the bucket for each position of the lifting boom and transfer boom. The normal position is understood here to mean the position in which the bucket is normally held in the relevant position of the lifting boom and transfer boom. In other words, the first pressure levels pl illustrated in Figure 2 are established in step 204 of Figure 8.

Consequently, after step 204 in Figure 8, it is known what kind of pressure levels occur in the lifting cylinder and bucket cylinder at any measurement point of the lifting boom and transfer boom in the selected operating range when the bucket is in its normal position. In this context, a selected operating range is understood to mean a range from one end of the measurement points to the other.

In step 206, the position compensation curves for the bucket are captured separately in the memory register for an empty bucket and for a full bucket. This occurs by first carrying out two calibration lifts with an empty bucket with the transfer boom at its innermost position point. During the first lift, the bucket is pivoted into a highest, i.e. innermost, desirable position for the duration of the lift. Figure 4 depicts this position of the bucket and transfer boom. During the second lift, the bucket is pivoted into an outermost, i.e. lowest, desirable position, as illustrated in Figure 5.

Figures 4 - 7 illustrate different positions of the lifting boom 40 and transfer boom 42 of the boom 18 as well as different positions of the bucket 12 during calibration. The same drawings show example positions of the boom 18 and bucket 12 whether the bucket is full or empty.

During the lifting in step 208 of Figure 8, these real-time positions of the bucket are measured and captured during a first lift in a table Bucket InPosArmlnPos [Lift_Pos] in indices indicated by the position of the lifting boom. The difference between the pressure values measured for the lifting cylinders and the corresponding pressure values of the lifts carried out with the bucket in the normal position is captured accordingly in a table Bucket InPosArmlnPosLif tDAdcEmpty [Lift_Pos] . Corresponding values are captured for the bucket cylinder in a table Bucket InPosArmlnnerPosBucketDAdcEmpty [Lift_Pos] . In the second lift, the bucket is held in the outermost desirable position during the lift and the corresponding measurements are captured in the tables BucketOutPosArmlnPos [Lift_Pos] , BucketOutPosArmlnPosLiftDAdcEmpty [Lift_Pos] and BucketOutPosArmlnPosBucketDAdcEmpty [Lift_Pos] . The transfer boom is then moved to the next position point and the same lifts are performed until the lifts have been performed in all positions of the transfer boom.

The corresponding lifts are then carried out in the outermost position of the transfer boom with an empty bucket in step 210. The bucket 12 is held in an innermost desirable position as illustrated in Figure 6 during a first lift and measurements are captured in the tables Bucket InPosArmOutPos [LiftPos] (bucket positions) , BucketlnPosArmOutPosLiftDAdc [LiftAdc] (differences in lifting cylinder pressure relative to the corresponding base calibration lift) and

BucketlnPosArmOutPosBucketDAdcEmpty [LiftPos] ( corresponding values of the bucket cylinder) . In step 212, the next lift is performed in the same position of the transfer boom, wherein during the lift the bucket is out of the base position by a desirable amount, as illustrated in Figure 7. The corresponding values are captured in the following tables: BucketOutPosArmOutPos [LiftPos] , BucketOutPosArmOutPosLiftDAdcEmpty [LiftPos] and

BucketOutPosArmOutPosBucketDAdcEmpty [LiftPos ] .

Next, in step 214 of Figure 8, the same lifts are performed at the same slow speed as previously for the bucket position compensation curves with an empty bucket, but with a full load. In each lift, the bucket is ideally held in exactly the same position as in the previous lifts with an empty bucket for the entire duration of the lift. To this end, instructions for maintaining the correct position can be displayed to the user via the interface. The mass in the bucket and the distribution of the mass are exactly the same as in the base calibration lifts of step 204. The corresponding values are captured in the following tables: Bucket InPosArmlnPosLif tDAdcFull [LiftPos] and Bucket InPosArmlnPosBucketDAdcFull [LiftPos] .

In the next lift, with the bucket in its outermost position, the values are captured in the following tables: BucketOutPosArmlnPosLif tDAdcFull [LiftPos] and

BucketOutPosArmInPosBucketDAdc_Full [LiftPos] .

In the next lift, with the transfer boom in its outermost position, initially with the bucket in its inner position, the values are captured in the following tables:

Bucket InPosArmOutPosLif tDAdcFull [LiftPos] and

BucketlnPosArmOutPosBucketDAdcFull [LiftPos ] , and subsequently, with the bucket in its outermost position, in the following tables:

BucketOutPosArmOutPosLif tDAdcFull [LiftPos] and

BucketOutPosArmOutPosBucketDAdcFull [LiftPos] .

It is thereby possible to establish, in step 206, comparative pressure values relative to a base position calibration with different bucket positions for all of the different positions of both the transfer boom and lifting boom, both with an empty bucket and with a full bucket, which permits a compensation of the relevance of a bucket position for a weight measurement. In other words, in step 206, the second pressure levels p2 are established .

In a third step, i.e. in step 216, the effect of a noncentrality of a load is captured, i.e. the third pressure levels p3 are established. The detection of a non-centrality is based on the measurement of a change in the pressure ratio between the lifting cylinders and the bucket cylinders, wherein the effects of the position of the boom and bucket have been eliminated in the measurement through compensation. There thus remain two factors that affect this pressure relationship - the magnitude of the load and a non-centrality of the load.

This step is performed analogously to the position compensation for the bucket in step 206, but now the load is placed non- centrally in the bucket at the tip of the bucket. This mass does not have to be the same as the load used in the base calibration, as long as the mass is known and the location of its centre of gravity is known. A further difference with respect to step 206 is that an additional lift is performed with the bucket in exactly the same position (normal position) as it was in the base calibration during the entire lift. That is to say that three lifts are performed with the transfer boom in its innermost position and a further three lifts are performed with the transfer boom in its outermost position. The bucket is pivoted first into its innermost position, then into its normal position and finally into its outermost position for the respective lifts. A non-centrality of the load in the bucket is identical for all lifts. The system directs a user to keep the bucket in the correct position during each lift by means of the display.

During the lifting movements, the pressure of the lifting cylinders and bucket cylinders is measured with the object of determining, for the lifting cylinders and bucket cylinders, pressure differences relative to a situation in which the same load is distributed symmetrically in the bucket. This can occur in two ways, either by carrying out two lifts for each bucket position, the first with the load distributed symmetrically (as in the base calibration) in the bucket and the second lift with the load distributed asymmetrically at the tip of the bucket. This would double the number of lifts required. The other option is to carry out the lifts with an asymmetrical load only. In this case, however, it is necessary to compute, by means of the base calibration data, what the pressure values of the lifting cylinders and bucket cylinders would be if the same load was distributed symmetrically, since the load being employed is not necessarily the same as in the base calibration.

Specifically, in step 216, step 218, in which a first lift with a non-central load is performed while keeping the bucket in the innermost position during the lift, is performed first. The first set of three lifts thus occurs with the transfer boom in the inner position, whereby the pressure of the lifting cylinders corresponding to a symmetrical load is obtained for each position point of the lifting boom as follows: where PPKG is the mass used in the non-central calibration step in kilograms and KalKg is the symmetrically distributed mass used in the base calibration. LiftPSym is the pressure of the lifting cylinder when the load is distributed symmetrically, as in the base calibration. The pressure difference of the cylinder of the lifting boom relative to a symmetrical load is captured during a lift for each position point of the lifting boom as follows:

BucketInPosArmInPosLiftDAdcPPKG[LiftPos] = LiftPSym — LiftP , where LiftP is the real-time pressure measurement value of the lifting cylinder . During the lifting movement, a corresponding pressure difference is also calculated for the bucket cylinder: }

BucketInPosArmInPosBucketDAdcEmpty[LiftP] = BkPSym, where BkPSym is the pressure of the bucket cylinder with the symmetrically distributed load in question. The pressure difference of the bucket cylinder relative to a symmetrical load is captured during a lift for each position point of the lifting boom as follows :

In step 220, a lift is performed while the bucket is held in the normal position, as in the base calibration. The lift pressure corresponding to a symmetrical load is obtained for each position point of the lifting boom as follows: and analogously for the bucket cylinder:

In step 222, a lift is performed with the bucket in the outermost position during the lift, the pressure corresponding to a symmetrical load being obtained as follows:

BucketOutPosArmInPosLiftDAdcPPKG[LiftPos] = LiftPSym — LiftP and for the bucket cylinder:

Finally, in step 224, the transfer boom is moved to the last outermost position point and the same lifting movements are performed, i.e. the point measurements of steps 216 to 220 are repeated in this position of the transfer boom. The collected measurements are captured in the same manner in respective corresponding tables and are stored in a permanent memory register, advantageously in a memory register of the central unit .

According to an embodiment, the position-corrected (for the bucket position) second pressure levels p2 determined in step 206 and the third pressure levels p3 of the asymmetrical load determined in step 216 can also be determined in such a manner that, instead of using an outermost and innermost position of the boom and an outer, inner and normal position of the bucket, the pressure measurements are advantageously performed at 8 to 12 measurement points comprising the aforementioned end positions of the boom and bucket and the normal position of the bucket, as in the base calibration of step 204. This permits an even more accurate calibration.

Figure 9 illustrates in a general manner tabular data collected in the memory register during the calibration lifts. The table contains, for every set position of the lifting boom and transfer boom, a measured value that depends on the position of the boom. This value can be the base position, i.e. the position of the bucket during the base calibration ( BucketNPos [ ] [] ) , the innermost bucket position ( Bucket InPos [ ] [] ) , the outermost bucket position ( BucketOutPos [ ] [] ) , the pressure of the lifting cylinders during the base calibration with a load ( LoadMapPressure [ ] [] ) , etc. The tables are advantageously all similar with the position of the transfer boom on the X-axis, the position of the lifting boom on the Z-axis, while the values measured in the calibration step that correspond to these positions constitute a third, Y- dimension .

Figure 9 depicts a situation in which the position of the lifting boom is between 8000...8400 and the position of the transfer boom is between 6000...6500. XILift and X2Lift are index indicators of the value table and in Figure 9 indicate table indices relating to the lifting boom while XIArm and X2Arm indicate indices relating to the transfer boom. The index indicator values are obtained by continuously comparing the measurement values of the position of the booms with the position point values of the booms contained in lookup tables specific to the booms. In the value table, the values corresponding to a position of the booms are in the same indices as in the lookup table, e.g. the value corresponding to the lifting boom position 8400 and the transfer boom position 6500 can be found in the value table under [1] [1] (transfer boom index 1, lifting boom index 1) . For example, in the case shown in Figure 9, the lookup table values for the lifting boom are:

Index 0: 8000, index 1: 8400, index 2: 8900, index 3: 9400, , ... etc. , while the lookup table values for the transfer boom are: 7000, 6500, 6000, 5500, 5200, 5000, etc.

In the case shown in Figure 9, the values of the index indicators are as follows:

- XILift = 0

- X2Lift = 1

- XIArm = 2

- X2Arm = 1

In the calculation routines, values are first calculated from the values Y1.1 (2900) and Y1.2 (3000) and from the values Y2.1 (3120) and Y2.2 (3200) in the value table for the lifting boom position. From these values, a final value is calculated relative to the transfer boom position. The method can be any curve fitting method; in the example a simple linear interpolation was used.

Put simply, the position of the booms is measured continuously and the value captured during calibration that corresponds to that position is retrieved from the value table and the exact value corresponding to the prevailing position of the booms between the value points in the value table is calculated.

As can be seen from Figures 4 - 7, the position of the bucket in relation to the rest of the boom is constantly changing according to the position of the boom. There is thus a need for bucket position maps, which are measured during calibration for the base position as well as for the inner and outer positions over the entire range of the boom. The pressure values of the lifting cylinder and bucket cylinders likewise change according to the position of the boom and bucket so that there is also a need for corresponding tables for said values.

Elements of the measurement step 202 are described in greater detail in the following. During the weight measurement, the data of the central unit includes real-time bucket position data a2 (BucketPos) , which it receives from the second position sensor, as well as the bucket position captured in the memory register during calibration for every possible orientation of the lifting boom and transfer boom (BucketPosNorm) . This is calculated by interpolating from base calibration curves according to the position of the booms (table BucketNPos [ArmP] [LiftP] ) . The weight measurement according to the method is performed while the boom is in motion so that, since it can be carried out while the boom is working, the weight measurement does not take any extra time.

The source data and corresponding abbreviations used in the measurement are indicated in the following. With respect to the abbreviations used in the measurement, LiftPos denotes the real-time lifting boom position data al .1 (typically a value between 1000 and 14000) , Lif tAngleBins [Lif t_Pos ] denotes the lifting boom positions captured in the table, of which there is a desired quantity, for example 8 (Lift_Pos=8) . Furthermore, the abbreviation Bucket InPosArmlnnerPos [Lif t_Pos ] denotes the position values captured in the table for the highest (innermost) bucket position with the transfer boom in the innermost position for each lifting boom position (e.g. Lift_Pos= 8) . Furthermore, the abbreviation Bucket InPosArmOuterPos [Lift_Pos ] denotes the position values captured in the table for the highest (innermost) bucket position with the transfer boom in its outermost position for each lifting boom position ( e . g . Lif t_Pos= 8) . The table can be a table similar to the one shown in Figure 9.

It is also necessary to take the bucket position into account in the calculation, as this position, in addition to the load and its distribution, has a large impact on the pressure of both the lifting cylinder and bucket cylinder. The so-called normal position of the bucket is the position used in the base calibration lifts and simultaneously constitutes the zero point on either side of which compensation values are calculated according to the position of the bucket. A situation in which the bucket position is higher than or equal to the base position of the bucket is described in the following. In cases where the bucket position is lower than the normal position, the calculation is performed in exactly the same manner, but with setting values corresponding to this bucket position range.

The object of these calculations (up to step 242) is to determine by means of the calibration data and the measurements what the bucket cylinder pressure would be if the load was symmetrical in the bucket (BucketAdcIf SymLoad) , i.e. the same as in the base calibration. In other words, fourth pressure levels p4 and a change (Apl) in the first pressure level are determined. It is then possible to calculate a second correction value C2 for the force (pressure) acting on the lifting cylinder from the centre- of-gravity calibration data (in order to compensate a potential uneven distribution of the load) . Finally, a compensation of the error resulting from the bucket position can occur for the pressure of the lifting cylinder by means of the correction value

C2 .

In the following step 224, the bucket is in a position further inward than the normal horizontal position, i.e. BucketPos>= BucketPosNorm . In this case, the highest or innermost bucket position that was used in the calibration step in the position of the lifting boom and transfer boom is calculated from the calibration data: where InnestBucketPos is the highest (innermost) bucket position that was used in the bucket position calibration in the relevant position of the lifting boom and transfer boom.

Then, in step 226, the difference between the pressure of the lifting cylinder when the bucket is empty and in its innermost position and the pressure of the lifting cylinder in the base calibration in which the bucket is in a normal position is calculated from the calibration data:

where InnestBucketPosLiftDAdcEmpty is the difference in the pressure of the lifting cylinder with an empty bucket when the bucket is in its innermost position relative to the normal position of the bucket in the relevant positions of the lifting boom and lifting cylinder. ( ArmAngleBins [ 0 ] denotes the innermost position value of the transfer boom while ArmAngleBins [ArmPosSize-1 ] denotes the outermost position value It is worth noting that the position reading of the transfer boom is highest when the transfer boom is in the inner position and decreases as it is moved outwards.

In step 228, the same calculation is performed for a full bucket.

where InnestBucketPosLiftDAdcFull is the difference in the pressure of the lifting cylinder with a full bucket (with the load of the base calibration lifts) when the bucket is in its innermost position relative to the corresponding pressure of the bucket cylinder when the bucket is in its normal position (anywhere in the area of the ranges of movement of the lifting cylinder and bucket cylinder) .

In step 230, the same calculations are performed for the pressure of the bucket cylinder:

where InnestBucketPosBucketDAdcEmpty is the difference in the pressure of the bucket cylinder with an empty bucket when the bucket is in its innermost position relative to the corresponding pressure of the bucket cylinder when the bucket is in its normal position (anywhere in the area of the ranges of movement of the lifting boom and transfer boom) .

Further, in step 232, the same calculations are performed for a full bucket :

where InnestBucketPosBucketDAdcFull is the difference in the pressure of the bucket cylinder with a full bucket when the bucket in its innermost position relative to the corresponding pressure of the bucket cylinder when the bucket is in its normal position (anywhere in the area of the ranges of movement of the lifting boom and transfer boom) .

After the pressure-difference calculations of steps 224 - 232, a difference in the pressure of the lifting cylinder relative to the position of the bucket (i.e. a difference in position of the bucket at the time of the measurement relative to the normal position of the bucket) is interpolated in step 234 for an empty bucket :

In step 236, a difference in the pressure of the lifting cylinder relative to the position of the bucket (i.e. a difference in position of the bucket at the time of the measurement relative to the normal position of the bucket) is interpolated for a full bucket.

Further, in step 238, a difference in the pressure of the bucket cylinder relative to the position of the bucket (a difference in position of the bucket at the time of the measurement relative to the normal position of the bucket) is interpolated for an empty bucket.

In step 240, a difference in the pressure of the bucket cylinder relative to the position of the bucket (a difference in position of the bucket at the time of the measurement relative to the normal position of the bucket) is interpolated for a full bucket

After the interpolation of the pressure differences for the lifting cylinder and bucket cylinder, it is calculated in step 242 what the bucket cylinder pressure would be if the load was symmetrical, as in the base calibration: where BucketAdcIf SymLoad is the bucket cylinder pressure if the load according to the lifting cylinder pressure lies in the bucket symmetrically. This was calculated from the bucket position-compensated lifting cylinder pressure. The value BucketAdcIf SymLoad will be required later in step 260, in which a correction value for an error resulting from the centre of gravity of a load is calculated for the lifting cylinder pressure. LoadMapBucketPressure is the bucket cylinder pressure in the base calibration in which the bucket is in the normal position and the load is symmetrical. LoadMapPressure is the corresponding lifting cylinder pressure, ZeroMapBucketPressure and ZeroMapPressure are respectively the lifting cylinder pressure without a load, with an empty bucket.

The change in lifting cylinder pressure resulting from a shifting of the calibration weight (PPKG) from the centre of the bucket to its tip is subsequently interpolated relative to the position of the lifting boom and transfer boom from the centre-of -gravity calibration data of the bucket. In other words, a change Ap2 in the second pressure levels is determined.

In step 244, an interpolation is carried out for the normal position of the bucket over the entire range of the lifting and transfer booms:

In step 246, the bucket is placed in the innermost (highest) position : In step 248, an interpolation from the preceding results is carried out relative to the position of the bucket:

The change in bucket cylinder pressure resulting from a shifting of the calibration weight (PPKG) from the centre of the bucket to its tip is then interpolated relative to the position of the lifting boom and transfer boom from the centre-of -gravity calibration data of the bucket.

In step 250, an interpolation is performed for the normal position of the bucket:

In step 252, the bucket is placed in the innermost (highest) position :

In step 254, an interpolation from the preceding results is carried out relative to the position of the bucket:

The centre-of -gravity calibration can be carried out with a different load than the actual base calibration. The PPKG value is the mass used in the centre-of-gravity calibration. In a given position of the bucket and in a given position of the lifting boom and transfer boom, the change in pressure resulting from a change in the centre of gravity behaves linearly for both the lifting cylinders and the bucket cylinders. In step 256, the values are scaled to a full load (to the load used in the base calibration) : where CalKg is the load used in the base calibrations, i.e. in the central calibration. In other words, a scaled change sAp2 in the second pressure level is calculated.

In step 258, the magnitude of the change in lifting cylinder pressure and the corresponding change in bucket cylinder pressure attributable to a change in the centre of gravity of the load in the bucket are calculated: where LiftDadc is the change in lifting cylinder pressure attributable to a change in the centre of gravity of the employed load and BucketDadc is the change in bucket cylinder pressure resulting from the same change in the centre of gravity

In step 260, a correction value for the error caused by the centre of gravity is calculated for the lifting cylinder pressure : where BucketAdc is the real-time pressure measurement value for the bucket cylinder and LiftAdc is the real-time pressure measurement value for the lifting cylinder. LiftAdcC is the measured lifting-cylinder pressure value in which an error caused by the centre of gravity of the load has been compensated

In step 262, a correction value for the error resulting from the position of the bucket is calculated for the lifting cylinder pressure. The contribution of the payload in the bucket is calculated: as well as an overall correction in step 264:

LiftPress LiftAdcC + LiftPressLCorr

Lif tAdcDelt aEToBucketNormPos where LiftPress is the final compensated lifting cylinder pressure based on which a determination of the mass of the load can occur. Lif tAdcDeltaEToBucketNormPos is the compensation of the error resulting from the position of the bucket for an empty bucket (calculated in step 234) , Lif tPressLCorr relates to the share of the load and LiftAdcC is the base value compensated for the centre of gravity. In this example, the first correction factor Cl for the bucket position correction consists of Lif tAdcDeltaEToBucketNormPos and Lif tPressLCorr together while the second correction factor C2 for a noncentrality of the load of the bucket consists in LiftAdcC.

The final corrected weighing result is obtained when the other correction factors are calculated for the lifting cylinder pressure. These factors can be lifting speed and lifting acceleration as well as a correction value for an error resulting from the position of the base machine. In an excavator, a correction factor is also calculated for a rotational movement of the boom since a rotational speed of the boom affects the central force affecting the load and thereby the force affecting the lifting cylinders.

The correction of an error resulting from a lifting speed can be performed with the formula LiftPress = LiftPress + Lif tSpeedEf f , where LiftSpeedEff is the error attributable to the lifting speed. The value is calculated from the calibration values that were measured at different lifting boom speeds in the calibration step.

The compensation of an error in bucket cylinder pressure resulting from a movement of the bucket cylinder can be calculated with the formula BkPress = BkPress + BkSpeedEff, where BkPress is the pressure value measured for the bucket cylinder (an A/D conversion from the pressure) and BkSpeedEff is the effect of a transient speed of movement of the bucket calculated from the calibration data. Correction advantageously occurs immediately after the pressure measurement before any other calculations. The value is calculated from the calibration values measured at different speeds of movement of the bucket cylinder in the calibration step. In the calibration, it is possible to measure the pressure level of the bucket cylinder while the bucket cylinder is being moved, for example, at a slowest, fastest and average speed during the operation of the lifting cylinder, whereby a change in the pressure level of the bucket cylinder resulting from a speed of movement of the bucket cylinder can be inferred.

The correction of an error resulting from a lifting acceleration can be performed with the formula: LiftPress = LiftPress + LiftAcEff, where LiftAcEff is the error attributable to a change in lifting acceleration, i.e. the speed of the lifting boom. This can be calculated from the calibration values measured at a known acceleration of the lifting boom during calibration.

In addition to the correction of an error resulting from an acceleration of the lifting boom, an error correction for a load acceleration caused by a movement of the base machine can also be implemented with the following formula: LiftPress = LiftPress + LoadAcEff, where LoadAcEff is the error resulting from the acceleration produced by a movement of the base machine, which occurs, for example, when driving over uneven ground. This is calculated based on the measurements of the acceleration sensor comprised by the bucket position sensor.

The correction of an error resulting from a longitudinal inclination of the base machine can be performed with the formula LiftPress = LiftPress + YangleEf f *sin ( a) , where YangleEff is the value that corresponds to the lifting boom position of the factor curve linked to the lifting boom position measured during calibration. The factor curve contains a separate factor for each position point of the lifting boom. The factors of the factor curve are measured during the calibration in both directions, for an inclination in the direction of the lifting boom and in the opposite direction. The variable a in the sinusoidal expression is the longitudinal angle of inclination of the base machine in radians. The factors for an empty bucket and for a loaded bucket are separate.

In addition to the correction of an error resulting from a longitudinal inclination, the correction of an error resulting from a lateral inclination can also be implemented with the formula: LiftPress = LiftPress + XangleEf f *sin (b) , where XangleEff is the factor measured during calibration for the lateral inclination. The variable b in the sinusoidal expression is the lateral angle of inclination in radians.

A correction of an error resulting from a rotational speed of the booms can be performed with the formula LiftPress = LiftPress + SwEff, where SwEff is the correction value calculated based on the calibration data and the measured rotational speed.

The final weighing result can be calculated with the following formula :

CalKg/ ( (LoadMapPressure-ZeroMapPressure) ) * (LiftPress- ZeroMapPressure ) = WeighResultKG where WeighResultKG is the complete measurement result.

A version of the method according to the invention is illustrated in the foregoing in which the bucket-position and centre-of -gravity calibration occurs at only two points, i.e. in an inner position and in an outer position, of the transfer boom. The method most universally used is identical with the exception that all lifts are carried out at every position point of the transfer boom. The only difference thus lies in the tables used, for example the table Bucket InPosArmlnPosLif tDAdcFull [LiftPos ] becomes

Bucket InPosLif tDAdcFull [ArmPos ] [LiftPos] , i.e. it contains a separate value for every position of the transfer boom and lifting boom.