Method, computer program and device for operating measurement encoder for rotational or linear movement

Abstract

The invention relates to a method for operating a measurement encoder for rotational or linear movement, in particular a measurement encoder having a plurality of detection sections, to a computer program with instructions, and to a device. The invention also relates to a machine in which the method according to the invention or the device according to the invention is used. In a first step, a measurement variable of a detection section is acquired (10). A confidence value is determined (11) from the acquired measurement variable and a previously acquired measurement variable. A current position value is then determined (12) on the basis of at least the acquired measurement variable, the previously acquired measurement variable and a confidence value. Subsequently, the determined current position value is output (13).

Description

Technical Field

[0001] The present invention relates to a method, a computer program with instructions, and a device for operating a measuring encoder for rotary or linear motion, in particular a measuring encoder having a plurality of sensing segments. The invention also relates to a machine in which the method or the device according to the invention is used. Background Art

[0002] Measuring the position of rotational or translational axes or servo axes (often also referred to as joints) is crucial in robotics and automation technology in general. In mobile robots, in particular, the limited installation space presents a challenge in integrating angle encoders or linear measuring systems into the mechanical design. If translational motion is achieved using a spindle drive, this assumes that the spindle drive has minimal mechanical backlash. This allows, for example, the use of an angle encoder designed as an absolute encoder to also detect linear paths.

[0003] Absolute encoders implemented as so-called multi-turn encoders are quite common in applications. For example, these encoders have an angle measuring device for 0° to 360° and a counter for the number of revolutions performed. However, to achieve multi-turn capability, these encoders are often equipped with a battery or additional electronics, resulting in packaging disadvantages or additional maintenance costs.

[0004] Angle encoders of very small design, which can also be integrated into very small installation spaces, are available in the form of single-turn absolute encoders. Here, there is the possibility of simulating multi-turn capability.

[0005] In this regard, Indian patent application 265 / MUM / 2002 describes a method for converting an n-bit single-turn absolute encoder into a programmable m*n-bit multi-turn absolute encoder, wherein the number of complete revolutions of the shaft of the single-turn absolute encoder is stored.

[0006] In the case of angle encoders with detection sectors, especially those with a linear output voltage, it can be observed that due to parasitic low-pass behavior, the transition from one detection sector to another cannot be clearly identified. Therefore, the identification threshold cannot be set at or slightly above the value of the maximum angular change per step, but rather at half the sector size of the detection sector, i.e., in the case of a detection sector with a sector size of 90°, at 45°.

[0007] Similar problems can also occur in linear measurement systems, where the measurement consists of a mixture of incremental and absolute parts. Summary of the Invention

[0008] The object of the present invention is to provide a solution for operating a measuring encoder for rotary or linear movements which allows for improved detection of transitions between detection segments.

[0009] This object is achieved by a method having the features of claim 1, by a computer program with instructions according to claim 8, by an apparatus having the features of claim 9, and by a machine according to claim 10. Preferred embodiments of the invention are subject matter of the dependent claims.

[0010] According to a first aspect of the present invention, a method for operating a measuring encoder for rotational or linear motion, wherein the measuring encoder has a plurality of detection segments, comprises the following steps: - Collect measurement parameters of the detection section; - determining a confidence value from the acquired measured variable and previously acquired measured variables; - determining a current position value based on at least the acquired measured variable, previously acquired measured variables and a confidence value; and - Outputs the determined current position value.

[0011] According to another aspect of the present invention, a computer program comprises instructions which, when executed by a computer, cause the computer to carry out the following steps for operating a measuring encoder for rotary or linear motion having a plurality of detection segments: - Collect measurement parameters of the detection section; - determining a confidence value from the acquired measured variable and previously acquired measured variables; - determining a current position value based on at least the acquired measured variable, previously acquired measured variables and a confidence value; and - Outputs the determined current position value.

[0012] The term "computer" is to be understood in this context in a broad sense and includes, in particular, control devices, embedded systems and other processor-based data processing devices.

[0013] The computer program may, for example, be provided for electronic retrieval or stored on a computer-readable storage medium.

[0014] According to another aspect of the invention, a device for operating a measuring encoder for rotary or linear motion having a plurality of sensing segments comprises: - Signal processing unit, used to collect measurement parameters of the detection section; a calculation unit for determining a confidence value from the acquired measured variable and previously acquired measured variables and for determining a current position value based on at least the acquired measured variable, the previously acquired measured variable and the confidence value; and - An output unit for outputting the determined current position value.

[0015] The solution according to the invention uses a filter that is based on a confidence interval for the acquired measured variables and, depending on the confidence value, instead of directly adopting the measured variables, refers back to the acquired measured variables of the preceding step and thus provides an estimated value. This achieves increased robustness with minimal computational effort.

[0016] According to one aspect of the invention, the confidence value is determined based on the difference between the acquired measured variable and a previously acquired measured variable. Using the difference has the advantage that in this way the confidence value depends on the change in the measured variable rather than the absolute value of the measured variable.

[0017] According to one aspect of the present invention, the confidence value is determined using a function that provides high confidence values ​​for the difference between 0 and a lower limit value and for the difference between an upper limit value and a segment variable of the detection segment, and that provides lower confidence values ​​for the difference between the lower limit value and the upper limit value. This ensures that the function only provides high confidence values, for example, a full confidence value of 1, for very small changes. All values ​​between the two limit values ​​are considered less trustworthy.

[0018] According to one aspect of the present invention, when determining the current position value, the current position change is determined from the previous position change and the difference value. For example, the current position change can be determined as a weighted sum of the previous position change weighted by the complement of the confidence value and the difference value weighted by the confidence value. Thus, the current position change is an estimate reflecting confidence in the sensor value. The current position value can then be determined in a simple manner as the sum of the previous position value and the current position change.

[0019] According to one aspect of the present invention, in the case of a high confidence value, the current position value and the current position change are corrected based on a sliding average formation. When the confidence value is again high, for example, 1, iteration is performed to the sensor value. To this end, the newly calculated position value and the position change value are corrected based on a sliding average formation. This step is advantageous because, in the case of measured values ​​with reduced confidence values, for example, a confidence value less than 1, the integrated position calculation can lead to errors. After a number of steps, the position value and the confidence value are matched again.

[0020] The method or device according to the invention is particularly advantageous for use in machines, in particular in vehicles or industrial machines. Vehicles can be, for example, motor vehicles, such as passenger cars or commercial vehicles. In principle, the solution according to the invention can be applied in all situations where angle or length detection is required, such as in regulating devices for dampers, valves, doors, etc. Industrial machines can be, for example, robots or other automated systems in which angle or length detection is required. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Further features of the present invention will become apparent from the following description and appended claims, taken in conjunction with the accompanying drawings.

[0022] Figure 1 A method for operating a measuring encoder is schematically shown; Figure 2 A first embodiment of a device for operating a measuring encoder is shown; Figure 3 A second embodiment of a device for operating a measuring encoder is shown; Figure 4 A transport vehicle is schematically shown as an example for a machine in which the solution according to the invention is implemented; Figure 5 Schematic illustration of an angle encoder with an analog output signal; Figure 6 An algorithm for implementing the method according to the present invention is shown by way of example; Figure 7 shows an exemplary function for determining a confidence value; and Figure 8 Shown by Figure 6 The results of signal evaluation by the algorithm in . DETAILED DESCRIPTION

[0023] In order to better understand the principle of the present invention, the embodiments of the present invention will be explained in more detail below according to the accompanying drawings. Obviously, the present invention is not limited to these embodiments, and the described features can also be combined or modified without departing from the scope of protection of the present invention as defined by the appended claims.

[0024] Figure 1A method for operating a measuring encoder with multiple detection segments is schematically illustrated. In a first step, a measurement variable of a detection segment is acquired 10. A confidence value is determined 11 from the acquired measurement variable and a previously acquired measurement variable, for example, based on the difference between the acquired measurement variable and the previously acquired measurement variable. To determine the confidence value 11, a function is preferably used that provides a high confidence value for the difference between 0 and a lower limit value and for the difference between an upper limit value and a segment variable of the detection segment, and a lower confidence value for the difference between the lower limit value and the upper limit value. A current position value is then determined 12 based on at least the acquired measurement variable, the previously acquired measurement variable, and the confidence value. To this end, the current position change can be determined from the previous position change and the difference between the acquired measurement variable and the previously acquired measurement variable. For example, the current position change can be determined as a weighted sum of the previous position change weighted by the complement of the confidence value and the difference weighted by the confidence value. The current position value can then be determined as the sum of the previous position value and the current position change. The determined current position value is then output 13. In the case of a high confidence value, the current position value and the current position change can also be corrected beforehand based on a sliding average formation.

[0025] Figure 2 A simplified schematic diagram of a first embodiment of a device 20 for operating a measuring encoder 1 for rotary or linear motion with a plurality of detection segments is shown. The device 20 has an input 21, via which a signal processing unit 22 detects the measured variables M of the detection segments. i The calculation unit 23 is configured to calculate from the acquired measurement variables M i and the previously acquired measurement variable M i-1 Determine the confidence value C i , for example based on the acquired measurement variable M i and the previously acquired measurement variable M i-1 In order to determine the confidence value C i , preferably a function is used which provides a high confidence value C for the difference between 0 and the lower limit value and for the difference between the upper limit value and the segment parameter of the detection segment i , and the function provides a lower confidence value C for the difference between the lower and upper values i The calculation unit 23 is further configured to calculate, based on at least the acquired measurement variable M i , previously collected measurement parameters M i-1 and confidence value C i To determine the current position value W i For this purpose, the previous position change and the acquired measurement variables M can be used. i The previously acquired measurement variable M i-1For example, the current position change can be determined as the difference between the confidence value C i The previous position change weighted by the complement of i The weighted sum of the weighted differences. Then, the current position value W can be i The output unit 24 is configured to output the determined current position value W via the output terminal 27 of the device 20. i In the case of high confidence values, the current position value W can also be corrected beforehand by the calculation unit 23 based on the sliding mean value formation. i and current location changes.

[0026] The signal processing unit 22, the computing unit 23, and the output unit 24 can be controlled by a control unit 25. Through a user interface 28, the settings of the signal processing unit 22, the computing unit 23, the output unit 24, or the control unit 25 can be changed when necessary. The data accumulated in the device 20 can be stored in a memory 26 when necessary, for example, for subsequent evaluation or for use by components of the device 20. The signal processing unit 22, the computing unit 23, the output unit 24, and the control unit 25 can be implemented as dedicated hardware, for example, as an integrated circuit. Of course, they can also be partially or completely combined or implemented as software running on a suitable processor, such as a GPU or a CPU. The input end 21 and the output end 27 can be implemented as separate interfaces or a combined bidirectional interface.

[0027] Figure 3 A simplified schematic diagram of a second embodiment of a device for operating a measuring encoder for rotary or linear motion with multiple detection segments is shown. The device 30 has a processor 32 and a memory 31. The device 30 is, for example, a computer or a control device. Instructions are stored in the memory 31, which, when executed by the processor 32, cause the device 30 to carry out the steps of one of the described methods. The instructions stored in the memory 31 thus represent a program that can be executed by the processor 32 and implements the method according to the invention. The device 30 has an input 33 for receiving information, for example information about the operating behavior of a machine user. The data generated by the processor 32 are made available via an output 34. Furthermore, they can be stored in the memory 31. The input 33 and the output 34 can be combined into a bidirectional interface.

[0028] Processor 32 may include one or more processor units, such as a microprocessor, a digital signal processor, or a combination thereof.

[0029] The memories 26 , 31 of the described embodiments may have both volatile and non-volatile storage areas and include different storage devices and storage media, such as hard disks, optical storage media or semiconductor memories.

[0030] Figure 4 A vehicle is schematically shown as an example of a machine 40 in which the solution according to the present invention is implemented. In this example, the vehicle is a motor vehicle. In this example, the motor vehicle has a control device 41 for a valve. Control device 41 is equipped with a measuring encoder 1. To operate measuring encoder 1, the motor vehicle has a device 20 according to the present invention. Other components of the motor vehicle include an infotainment system 42 with a display 43, several assistance systems 44, an environmental sensor system 45 (such as a camera, radar sensor, lidar sensor, or ultrasonic sensor) for acquiring environmental information, and a data transmission unit 46. The assistance systems 44 can access the measured values ​​of measuring encoder 1 as needed. Data transmission unit 46 can, for example, establish a connection to a backend, for example, to transfer settings or retrieve updated software for motor vehicle components. A memory 47 is provided for data storage. Data exchange between the various components of the motor vehicle occurs via a network 48.

[0031] The following should be based on Figure 5 FIG. 9 indicates further details of the solution according to the invention.

[0032] Figure 5 The schematic diagram shows an angle encoder, i.e., a measuring encoder 1 for rotary motion, with an analog output signal. The angle encoder exemplarily has four detection segments S1-S4, i.e., four sectors, each with an angular range of 90°. However, other configurations are also possible, for example, with semicircular segments or full circles. Each detection segment S1-S4 provides a linear analog output signal, in this example a voltage between 0 mV and 5000 mV.

[0033] Figure 6 An algorithm for implementing the method according to the present invention is shown by way of example. In this example, Figure 5The measured angle is determined in the case of an angle encoder in . Therefore, the pseudocode shown relates to the sector size of a 90° angle encoder. Whenever 90° or 45° is used as an operator in the pseudocode, the sector size or half a sector size should generally be used there. After starting in block 100, the raw value of the voltage (voltageRaw) is read in the first block 110, and the raw angle (angleValueRaw(i)) is calculated from this. In addition, the difference (delta_alpha(i)) between the raw angle and the previously determined raw angle is calculated. This difference is divided into an absolute value (abs_delta_alpha(i)) and a sign (sign_delta_alpha(i)). A confidence value (conf_val(i)) is determined from the absolute value of the difference. The function used for this purpose is optional. In the subsequent comparison block 120, a check is performed to see whether the difference is greater than half a sector size. If this is the case, the angle step is evaluated as a safe sector transition, and in block 130, the difference is first reduced by the sector size. In any case, the difference is then restored from the absolute value and the sign in block 140. In the following block 150, the angle step (stepAngle(i)) is estimated as the weighted sum of the previous angle step weighted by the complement of the trust value and the current difference weighted by the trust value. The current value of the angle (angleValueSens(i)) is then the sum of the last value of the angle and the angle step. This value lies within the total possible angle range between the minimum angle and the maximum angle. The next query in block 160 checks whether the trust value is equal to 1. If not, the calculation ends. If so, the newly calculated angle and the angle step are corrected in block 170 based on the formation of a sliding average. This step is advantageous because, in the case of measured values ​​with a trust value less than 1, the integrated angle calculation can lead to errors. Before the sliding average is formed, the current detection segment (segSens) is first determined. After a few steps, the values ​​of the angle and the angle step match again. The algorithm finally ends with block 180.

[0034] Figure 7 An exemplary function for determining a confidence value is shown. The confidence value C is shown. i As the difference D between the acquired measured variable and the previously acquired measured variable iThe absolute value of . In this example, it is the difference between the original angle and the previously determined original angle (abs_delta_alpha(i)). In principle, when the difference is small (0°...G1 or G2...90°), the function provides the value "1", that is, full trust. All values ​​in between are less trustworthy. The range G2...90° corresponds to the sector transition. The solid line trend between the extreme values ​​G1, G2 can be described, for example, by the fourth power. Such a function provides very robust results. Alternatively, a linear trend can also be used, as reflected by the dotted line.

[0035] Figure 8 Shown by Figure 6 Here, Figure 8 a) shows the time profile of the raw value of the voltage (voltageRaw). Figure 8 b) shows the raw angle (angleValueRaw), the absolute value of the difference between the raw angle and the previously determined raw angle (abs_delta_alpha), and the associated progression of the angle step (stepAngle). Figure 8 c) shows the course of the current detection segment (segSens), calculated once without filtering and once with filtering, and the course of the confidence value (conf_val). Figure 8 d) Finally, the time course of the angle (angleValueSens) is shown, once calculated without filtering and once with filtering. As can be clearly seen, directly adopting the measured values ​​in the region of sector transitions can lead to large jumps in the angle. These jumps are significantly reduced by filtering the values ​​according to the present invention. The filtering has a significant effect only within the small time window in which the confidence value deviates from "1." The two trends then quickly converge again.

[0036] Reference Signs List 1 Measuring encoder 10. Collecting measurement parameters 11 Determining the confidence value 12 Determine the current position value 13 Output the determined current position value 20 devices 21 Input 22 signal processing unit 23 computing units 24 output units 25 control unit 26 Memory 27 Output 28 User Interface 30 devices 31 Memory 32 processors 33 Input 34 output terminals 40 machines 41 Adjustment equipment 42 Infotainment System 43 Display device 44 auxiliary systems 45 Environmental Sensing Device 46 Data Transmission Unit 47 Memory 48 Network 100 - 180 Procedure Steps C i Confidence value D i Difference G1 lower limit G2 upper limit M i Measurement parameters S i Detection section SG segment parameters W i Position value WS i Position changes

Claims

1. A method for operating a measuring encoder (1) for rotational or linear motion, wherein the measuring encoder has a plurality of detection segments (S i ), the method comprising the following steps: - Acquisition (10) detection section (S i ) of the measured parameter (M i ); - From the acquired measurement variables (M i ) and previously acquired measurement variables (M i-1 ) Determine (11) the confidence value (C i ); - Based on at least the acquired measurement variables (M i ), the previously acquired measurement variables (M i-1 ) and the confidence value (C i ) to determine (12) the current position value (W i );as well as - Output (13) the current position value (W i ).

2. The method according to claim 1, wherein The confidence value (C i ) based on the acquired measurement parameters (M i ) and the previously acquired measurement variables (M i-1 ) difference (D i ) to determine (11).

3. The method according to claim 2, wherein: The confidence value (C i ) is determined (11) by means of a function (F) for the difference (D) between 0 and a lower limit value (G1) i ) and for the upper limit value (G2) and the detection section (S i ) between the segment parameters (SG) (D i ) provides a high confidence value, and the function is for the difference (D i ) provides a lower confidence value.

4. The method according to claim 2 or 3, wherein: In determining (12) the current position value (W i ), changes from the previous position (WS i-1 ) and the difference (D i )Determine the current position change (WS i ).

5. The method according to claim 4, wherein The current position change (WS i ) is determined as the confidence value (C i )'s complement weighted previous position change (WS i-1 ) and the confidence value (C i ) weighted difference (D i ) is the weighted sum of .

6. The method according to claim 5, wherein: The current position value (W i ) is determined (12) as the previous position value (W i-1 ) and the current position change (WS i ) and.

7. The method according to any one of claims 4 to 6, wherein At high confidence values ​​(C i ), the current position value (W i ) and the current position change (WS i ).

8. A computer program having instructions which, when executed by a computer, cause the computer to carry out the steps of the method according to any one of claims 1 to 7 for operating a measuring encoder (1) for rotary or linear movements.

9. A device (20) for operating a measuring encoder (1) for rotational or linear motion, wherein the measuring encoder has a plurality of detection segments (S i ), the device having: - a signal processing unit (22) for collecting (10) the detection section (S i ) of the measured parameter (M i ); - a calculation unit (23) for calculating the acquired measurement variables (M i ) and previously acquired measurement variables (M i-1 ) Determine (11) the confidence value (C i ) and for determining, based on at least the acquired measured variable (M i ), the previously acquired measurement variables (M i-1 ) and the confidence value (C i ) Determine (12) the current position value (W i ); as well as - Output unit (24), for outputting the current position value (W i ).

10. A machine (40), characterized in that The machine (40) has a device (20) according to claim 9 or is configured to carry out a method according to any one of claims 1 to 7 for operating a measuring encoder (1) for rotary or linear motion.

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