Compensation angle determination method

Abstract

To provide a compensation angle determination method of a work machine component capable of pivoting between a first terminal position and a second terminal position relative to a reference component.SOLUTION: The compensation angle determination method executes: a calibration phase for pivoting a component to a first terminal position, detecting a first sensor angle value at the first terminal position, pivoting the component to a second terminal position, detecting a second sensor angle value at the second terminal position, determining a hysteresis angle value from a sensor angle difference between the first sensor angle value and the second sensor angle value and a terminal position angle difference; and a use phase for determining a compensation angle by detecting a sensor angle value for a specific point in time, identifying whether a positive turning direction or a negative turning direction of the component exists at the specific point in time, and correcting the sensor angle value at the specific point in time by an angle correction amount depending on the hysteresis angle value and the turning direction.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for determining a compensation angle, a computing unit, a computer program for implementing the method, and a working machine.

Background Art

[0002] Background of the Invention In mobile working machines, such as excavators, wheel loaders, telescopic handlers or cranes, it is often important to calculate the position of an element (for example, the position of the upper carriage of an excavator relative to the world coordinate system) or the position of an individual joint (for example, the position of the boom joint, the leg joint, the spoon joint). Knowledge of such variables is useful, for example, for providing the operator with accurate feedback regarding the position of the working tool, or for implementing closed-loop control algorithms or open-loop control algorithms for, for example, working space limitations or coordinate control. To determine the position of an element, methods can be used, for example, to measure the stroke in a cylinder (for example, by measuring magnetostriction), or to measure the joint angle (for example, using a potentiometer or an optical encoder or a magnetic encoder, or using an inertial sensor device).

Summary of the Invention

Problems to be Solved by the Invention

[0003] Disclosure of the Invention According to the present invention, there is proposed a method for determining a compensation angle, a computing unit, a computer program for implementing the method, and a working machine having the features of each independent claim. Advantageous configurations are the subject of each dependent claim and the following description.

Means for Solving the Problems

[0004] The present invention uses a calibration phase and an operation phase to determine a compensation angle of a component of a working machine that can pivot between a first end position and a second end position relative to a reference component, and utilizes a countermeasure of measuring or detecting a sensor angle value by an angle sensor coupled to the component and the reference component. In the calibration phase, the component is sequentially pivoted to the first end position and the second end position, and the corresponding sensor angle values are detected, and a hysteresis angle value is determined from these sensor angle values. In the operation phase, the sensor angle value and the pivoting direction for a specific time point are detected or determined, and a compensation angle is determined by correcting the sensor angle value by an angle correction amount that depends on the hysteresis angle value and the pivoting direction. By the method of the present invention, that is, by particularly considering the hysteresis angle value and the pivoting direction in angle correction, a consistent value representing the compensation angle that compensates for an error caused by play in the mechanical coupling of the angle sensor to the component and the reference component can be determined. In particular, the compensation angle is independent of the pivoting direction.

[0005] According to one configuration, in the positive pivoting direction, the first part of the hysteresis angle value is added to the sensor angle value at a specific time point, and in the negative pivoting direction, the second part of the hysteresis angle value is subtracted from the sensor angle value at a specific time point. In particular, the sum of the first part and the second part of the hysteresis angle value is equal to the hysteresis angle value. The first part and the second part of the hysteresis angle value may be equal to 1 / 2 of the hysteresis angle value. According to such a configuration, the compensation angle is within a band defined by hysteresis, for example, located at the center of the band.

[0006] According to one configuration, the turning direction is determined based on the sensor angle values at consecutive time points. Here, the turning direction is specified as positive when the sensor angle value increases between consecutive time points, and is specified as negative when the sensor angle value decreases between consecutive time points. Therefore, when the sensor angle value changes in the direction of a larger angle, it starts from the positive turning direction. Correspondingly, when the sensor angle value changes in the direction of a smaller angle, it starts from the negative turning direction. Since this configuration is based on an existing variable (the sensor angle value), it can be easily realized.

[0007] According to one configuration, the turning direction is determined based on measurements by a sensor different from the angle sensor, particularly an inertial sensor. The method here does not depend on the measurement of the angle sensor, and is particularly advantageous because the measurement error does not act on both the sensor angle and the turning direction.

[0008] According to one configuration, each step of the usage phase is repeatedly executed without temporarily performing a calibration phase. Such repeated execution of each step of the usage phase can be particularly continuous, so that newly generated sensor angle values are compensated each time.

[0009] According to one configuration, a calibration phase is newly executed to update the hysteresis angle value. In particular, the new execution of the calibration phase is executed at at least one predetermined time point, and / or in response to at least one predetermined event, and / or in response to a corresponding input from the operator of the working machine. By doing so, for example, changes that may occur in the hysteresis angle based on wear can be taken into account.

[0010] The calculation unit according to the present invention, for example, the control device of a movable working machine, is configured to implement the method according to the present invention, particularly by means of program technology.

[0011] The working machine according to the present invention comprises a component that is rotatable between a first end position and a second end position relative to a reference component, and there is a known end position angular difference between the first end position and the second end position. An angle sensor is provided that is (mechanically) coupled to the component and the reference component and is configured to measure the sensor angle value of the component relative to the reference component. Further, the working machine includes a calculation unit according to the present invention. The (mechanical) coupling may have play that causes hysteresis in the measured sensor angle value. This hysteresis is taken into account by the method according to the present invention in order to achieve consistent angle determination.

[0012] According to one configuration, the angle sensor has a detection element and an arm element that are fixedly arranged on the reference component. The arm element is rotatably supported on the reference component and engages with a trailing element that is fixedly arranged on the component. The play here may exist between the arm element and the trailing element in this case.

[0013] It is also advantageous to implement the method according to the present invention in the form of a computer program or a computer program product that includes program code for performing all method steps. This is because, in this way, particularly when the control device to be implemented is provided anyway for use in other tasks, only particularly low costs are incurred. Suitable data carriers for providing the computer program are, in particular, magnetic, optical and electrical memories, such as hard disks, flash memories, EEPROMs, DVDs, etc. It is also possible to download the program via a computer network (such as the Internet, intranet, etc.).

[0014] Further advantages and configurations of the present invention will become apparent from the specification and the accompanying drawings.

[0015] It should be understood that the above-described features and the features further described below can be used not only in the presented combinations but also in other combinations or alone without departing from the scope of the rights of the present invention.

[0016] The present invention will be schematically illustrated in the drawings in accordance with embodiments and will be described in detail below with reference to the drawings.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Modes for Carrying Out the Invention

[0018] Detailed Description of the Drawings In FIG. 1, the rotational movement or swiveling movement 16, 18 of the component 2 rotatable relative to the reference component 4 and the measurement of the corresponding angle by the angle sensor 8 are shown. The component 2 is attached to the reference component 4 by a rotary joint 6, whereby it can swivel or rotate relative to the reference component 4. The component 2 may be, for example, a delivery of an excavator, and the reference component 4 may be the upper carriage of the excavator or fixedly attached to the upper carriage. The rotational movement or swiveling movement of the component is performed by an actuator, such as a hydraulic cylinder (not shown). By measuring the angle, it is desirable to determine the rotational angle about the axis of the rotary joint 6 of the (rotatable) component 2 relative to the reference component 4. The rotatable component 2 is also abbreviated as component 2.

[0019] The component 2 has a first end position corresponding to the (true) minimum angle α min and a (true) maximum angle α maxIt is rotatable or swivellable between a second end position corresponding to min and a maximum angle α max itself is known, or since the direction corresponding to the zero angle (i.e., the orientation of the corresponding coordinate system) can be arbitrarily set, at least the true angular difference α max -α min between these two angles is known. This angular difference is also referred to as the end position angular difference.

[0020] For example, an angle sensor 8 is provided that has an element (referred to as a detection element) fixedly arranged on the reference component 4 and an element (referred to as an arm element 10) rotatably arranged on the reference component 4. The arm element 8 is rotatable, for example, about an axis that coincides with the axis of the rotary joint 6. Further, since the arm element 8 engages with an element fixedly arranged on the swivellable component 4, referred to as a trailing element 12, it rotates or is trailed together by the component 2. The trailing element 12 is, for example, a peg or a pin. The angle sensor 8 measures or detects the angle of the arm element 10 relative to the detection element, which is referred to as the sensor angle α Sens . For example, the arm element 10 and the detection element can form a potentiometer with a variable resistance corresponding to the angular value together with another element of the angle sensor. The angle sensor is configured to determine, in particular, the sensor angle value at that time (i.e., the value representing the sensor angle) continuously or at predetermined time intervals, regularly or irregularly spaced, for example, in a predetermined time pattern or at a predetermined measurement frequency. The angle sensor can further be configured to transmit the measured or predetermined sensor angle value at that time to an electronic control unit (computing unit), for example, the electronic control unit (not shown) of a working machine equipped with a swivellable component and a reference component.

[0021] There is a play between the arm element 10 and the follower element 12 that causes hysteresis in the angle measurement by the angle sensor 8. The resulting hysteresis curve is shown as a graph plotted against the sensor angle value α below FIG. 1 Sens with respect to the true angle α act . More generally, there is play due to the mechanical coupling of the angle sensor 8 with the component 2 and the reference component 4. Such play can cause hysteresis.

[0022] For example, the first swiveling movement 16 is performed in the direction of a smaller angle (negative swiveling direction), i.e., in the clockwise direction in the drawing, until the first end position or the true minimum angle α min is reached. In this case, the minimum angle measured by the angle sensor, i.e., the minimum sensor angle value α Sens (α min ) is likewise achieved. During the first swiveling movement 16, the peg, i.e., the follower element 12, is in contact with the fork-shaped end portion of the arm element 10 located in the clockwise direction.

[0023] After the reversal of the movement, the second swiveling movement 18 is performed in the direction of a larger angle (positive swiveling direction), i.e., in the counterclockwise direction in the drawing, until the second end position or the true maximum angle α max is reached. After the transition phase, the peg, i.e., the follower element 12, is in contact with the fork-shaped end portion of the arm element 10 located opposite to the clockwise direction during the second swiveling movement 18. The transition between the portions where the follower element abuts, i.e., the play here, causes the angle measured by the angle sensor 8, i.e., the sensor angle value, to first remain at the minimum sensor angle value α Sens (α min ) immediately after the reversal of the movement. That is, although the change in the true angle α act has already occurred, the sensor angle value remains unchanged for the time being. When the true maximum angle α max is reached, the maximum angle measured by the angle sensor, i.e., the maximum sensor angle value αSens (α max ) can be obtained in the same manner.

[0024] Subsequently, when a new movement in the direction of a smaller angle, i.e., a new movement in the clockwise direction, is performed, here too, immediately after the reversal of the movement, based on the play, the true angle α act Although already reduced, the sensor angle value remains at approximately the maximum sensor angle value α Sens (α max ) for a phase.

[0025] Due to such hysteresis, a state where the measured sensor angle value cannot be uniquely associated with the true angle, or a state where the sensor angle value has an error with respect to the true angle, occurs. Such a problem is solved by determining the compensation angle α comp by the method according to the present invention.

[0026] FIG. 2 shows a flowchart of a method for determining the compensation angle of a component of a working machine that can pivot between a first end position and a second end position relative to a reference component, which is an embodiment of the present invention. The premise of the present invention is that an angle sensor configured to determine or measure a sensor angle value is provided. This corresponds to the arrangement shown in FIG. 1. The method can be realized, for example, by executing a corresponding computer program (angle compensation program) by an electronic control unit (or a computing unit) of the working machine. The electronic control unit is configured to control an actuator that causes a pivoting movement of the component relative to the reference component, particularly (for example, by executing a corresponding actuator control program). In this case, the angle sensor transmits the measured sensor angle value at that time to the electronic control unit as described above. The compensation angle determined by the electronic control unit by this method can be further used by the electronic control unit for control tasks.

[0027] This method includes a calibration phase (steps 110 to 130) and an operation phase (steps 140 to 160).

[0028] In step 110, an approach to a first end position corresponding to, for example, a true minimum angle α (by corresponding drive control of the actuator) is performed. This approximately corresponds to the first turning motion 16 in FIG. 1. The corresponding sensor angle value at the first end position determined by the angle sensor is detected, and this sensor angle value is the first sensor angle value or the minimum sensor angle value α min (α Sens (α min ) is referred to as such. In this case, α Sens (α min ) = α min + α down holds true.

[0029] The deviation of the first sensor angle value or the minimum sensor angle value from the true minimum angle is referred to as the first offset angle α down . Generally, the first offset angle different from zero is due to play as described. Furthermore, the offset angle may include systematic deviations (caused especially by the setting of the zero angle).

[0030] Subsequently, in step 120, an approach to a second end position corresponding to, for example, a true maximum angle α (assuming the same inversion for clarity. That is, first an approach to the maximum angle is performed, and then an approach to the minimum angle is performed) is performed by corresponding drive control of the actuator. The corresponding sensor angle value determined by the angle sensor is detected, and this sensor angle value is the second sensor angle value or the maximum sensor angle value α max (α Sens (α max ) is referred to as such. In this case, α Sens (α max ) = α max + α up holds true.

[0031] The deviation of the minimum sensor angle value from the true maximum angle is the second offset angle α up which is also referred to as. In general, the second offset angle, which is different from zero, is due to the play described above (and in some cases also due to systematic deviations).

[0032] In step 130, the hysteresis angle value α hyst is determined. In particular, the hysteresis angle value α hyst is determined as the difference (referred to as the sensor angle difference) between the first offset angle and the second offset angle using the above formula. That is, α hyst = α down - α up = [α Sens (α min ) - α min - [α Sens (α max ) - α max is.

[0033] This can be rewritten as α hyst = [α Sens (α min ) - α Sens (α max )] - [α min - α max as.

[0034] In the above formula for the hysteresis angle value α hyst , the first expression (sensor angle difference) can be determined from the measured sensor angle value, and the second expression (terminal position angle difference) is known from the observed mechanical characteristics of the component. The hysteresis angle value is accordingly determined as the terminal position angle difference from the sensor angle difference. Any systematic deviations that occur appear in the second expression due to the difference. The hysteresis angle value α hyst is used for angle compensation in the following usage phase.

[0035] In step 140, at a specific time t B ​​Sensor angle value α with respect to Sens (t B ) is detected. That is, the angle measurement value of the angle sensor is detected. Specific time point t B may be, for example, the current time point.

[0036] In step 150, the turning direction of the component at the specific time point t B is determined. That is, it is specified whether the component is rotating in the direction of a larger angle or in the direction of a smaller angle. Rotation in the direction of a larger angle is referred to as the positive turning direction. Rotation in the direction of a smaller angle is referred to as the negative turning direction.

[0037] The turning direction can be specified, for example, by comparing consecutive sensor angle values (measured by the angle sensor). For example, sensor angle value α Sens (t k ) is detected at consecutive time points t k , where k is an integer, and the time points are arranged, for example, at regular intervals (t k+1 = t k + Δt, where Δt is constant). At this time, the positive turning direction can be said to exist when α Sens (t k ) > α Sens (t k-1 ) holds. The negative turning direction exists when α Sens (t k ) < α Sens (t k-1 ) holds.

[0038] The specific time point t B is particularly one of a plurality of consecutive time points t k .

[0039] In addition to comparing consecutive sensor angle values, other methods for determining the turning direction are also conceivable. For example, the measured values of one or more other sensors, such as inertial sensors, are evaluated. Also, for example, control signals for the actuator can also be evaluated for this purpose.

[0040] In step 160, the compensation angle α comp is determined. In this case, at a specific time point t B , the correction of the sensor angle value α Sens (t B ) is performed by an angle correction α hyst depending on the hysteresis angle value α korr and the turning direction S, that is, α korr = α korr (α hyst , S) holds, where S can take, for example, a value "pos" representing the positive turning direction and a value "neg" representing the negative turning direction. The angle correction is added specifically to the sensor angle value, that is, α comp (t B ) = α Sens (t B ) + α korr (α hyst , S) is obtained.

[0041] Specifically, in order to obtain the compensation angle α comp , in the positive turning direction, half of the hysteresis angle value α hyst is added to the sensor angle value α Sens (t B ), and in the negative turning direction, half of the hysteresis angle value α hyst is subtracted from the sensor angle value α Sens (t B ) so as to correct the sensor angle value α B (t Sens ) at a specific time point t B . In this case, the compensation angle α comp moves at the center of the hysteresis branch as shown in FIG. 1.

[0042] By the correction where 1 / 2 of the hysteresis angle value is added or subtracted, in the positive turning direction, α comp (t B ) = α Sens (t B ) + α korr (α hyst , pos) = α Sens (t B ) + α hyst / 2 holds, and in the negative turning direction, α comp (t B ) = α Sens (t B ) + α korr (α hyst , neg) = α Sens (t B ) - α hyst / 2 holds.

[0043] More generally, in addition to adding or subtracting 1 / 2 of the hysteresis angle value, other corrections can also be selected. For example, further, α comp (t B ) = α Sens (t B ) + α korr (α hyst , S) as a starting point, the angle correction amount as the product of the hysteresis angle value α hyst and the coefficient r(S) depending on the turning direction is α korr (α hyst , S) = r(S)·α hyst is obtained.

[0044] Here, for example, the coefficient r(S) is equal to a constant g (i.e., r(pos) = g) in the positive turning direction and 1 - the constant g (i.e., r(neg) = 1 - g) in the negative turning direction. The constant g is particularly between 0 and 1 (i.e., g ∈ [0, 1]). The constant g is the (first) part of the hysteresis angle value added to the sensor angle value in the case of the positive turning direction. 1 - the constant g (i.e., 1 - g) is the (second) part of the hysteresis angle value subtracted from the sensor angle value in the case of the negative turning direction.

[0045] Compensation angle α comp can be used to implement the control function of the working machine (e.g., in an appropriate control algorithm). In order to facilitate the operation of the working machine, for example, a display function or an instruction function that outputs information regarding the angle to the display unit of the working machine can also be implemented.

[0046] Steps 140 to 160 of the usage phase can be repeatedly executed continuously at various specific times, and thus, it is possible to jump from step 160 to step 140. In this case, the same hysteresis angle value can be used respectively, that is, steps 140 to 160 of the usage phase can be repeated without executing the calibration phase during the repetition.

[0047] As an optional means, in step 170, in order to update the hysteresis angle value, a new execution of the calibration phase can be triggered (i.e., jump to step 110). Step 170 can be executed at a predetermined time (e.g., regularly), and / or in response to a predetermined event (e.g., at the start of the working machine), and / or in response to a corresponding input from the operator of the working machine. It is convenient to newly determine the hysteresis angle value. This is because the play in the mechanical coupling between the angle sensor and the component and the reference component can change over time (e.g., due to wear) or due to temperature.

[0048] Furthermore, it can be configured to inspect whether the hysteresis angle value exceeds a predetermined maximum angle, and this inspection can be performed, for example, following step 130. At this time, if it is confirmed that the hysteresis angle value exceeds the predetermined maximum angle, an error message can be formed and output to, for example, the display unit of the working machine. Note that the error message can also be transmitted to a control algorithm that uses a compensation angle (for example, to implement an automatic control function), and in response to this transmission, the control algorithm may implement, for example, only limited functions.

Claims

1. The compensation angle (α) of the component (2) of the working machine which is rotatable between a first end position and a second end position relative to the reference component (4) is ｃｏｍｐ ) , comprising the steps of: a known end position angle difference exists between the first end position and the second end position; an angle sensor (8) coupled to the component (2) and to the reference component (4) and configured to measure a sensor angle value of the component (2) relative to the reference component; The method includes a calibration phase and a usage phase, The calibration phase comprises: The component (2) is pivoted to the first end position, and a first sensor angle value (α Ｓｅｎｓ (α ｍｉｎ )) (110, 16); and The component (2) is pivoted to the second end position, and a second sensor angle value (α Ｓｅｎｓ (α ｍｉｎ )) (120, 18); and determining (130) a hysteresis angle value from a sensor angle difference between the first sensor angle value and the second sensor angle value and the end position angle difference; Including, The use phase includes: Detecting (140) a sensor angle value for a particular point in time; Identifying (150) whether there is a positive or negative pivot direction of the component at the particular time; The sensor angle value at the specific time point is corrected by an angle correction amount that depends on the hysteresis angle value and the turning direction, thereby obtaining a compensation angle (α ｃｏｍｐ ) (160); and A method comprising:

2. The compensation angle (α ｃｏｍｐ a first portion of the hysteresis angle value is added to the sensor angle value at the particular time in a positive turning direction and a second portion of the hysteresis angle value is subtracted from the sensor angle value at the particular time in a negative turning direction to determine (160) The method of claim 1.

3. the sum of the first and second portions of the hysteresis angle value is equal to the hysteresis angle value; The method of claim 2.

4. the first and second portions of the hysteresis angle value are equal to ½ of the hysteresis angle value; The method according to claim 2 or 3.

5. The hysteresis angle value is determined as the sensor angle difference minus the end position angle difference.

5. The method according to any one of claims 1 to 4.

6. The turning direction is determined (150) based on sensor angle values ​​at successive times; the turning direction is identified as positive if the sensor angle value increases between the successive time points, and is identified as negative if the sensor angle value decreases between the successive time points.

6. The method according to any one of claims 1 to 5.

7. The turning direction is determined (150) based on measurements by a sensor different from the angle sensor (8), in particular an inertial sensor.

7. The method according to any one of claims 1 to 6.

8. Each step of the use phase is repeatedly executed without temporarily executing the calibration phase.

8. The method according to any one of claims 1 to 7.

9. the calibration phase is performed again to update the hysteresis angle value; In particular, a new execution of the calibration phase is performed at at least one predefined time point and / or in response to at least one predefined event and / or in response to a corresponding input of an operator of the work machine.

9. The method according to any one of claims 1 to 8.

10. A computing unit comprising a processor configured to carry out the method according to any one of claims 1 to 9.

11. A working machine comprising a component (2) that is pivotable between a first end position and a second end position relative to a reference component (4), a known end position angle difference exists between the first end position and the second end position; an angle sensor (8) coupled to the component (2) and to the reference component (4) and configured to measure a sensor angle value of the component relative to the reference component; Further, a calculation unit according to claim 10 is provided. Working machinery.

12. The angle sensor (8) comprises a detection element fixedly arranged on the reference component (4) and an arm element (10), The arm element (10) is rotatably supported on the reference component and engages with a driving element (12) fixedly arranged on the component (2), 12. A work machine according to claim 11.

13. A computer program comprising instructions for triggering the implementation of a method according to any one of claims 1 to 9, when the program is executed by a computer.

14. A computer readable data carrier storing a computer program according to claim 13.

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