Method, computer program and device for operating a transducer for a rotational or linear movement

Abstract

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

Description

[0001] Description

[0002] Method, computer program and device for operating a measuring sensor for a rotary or linear movement

[0003] The present invention relates to a method, a computer program with instructions, and a device for operating a measuring sensor for a rotary or linear movement, in particular a measuring sensor having a number of detection sections. The invention further relates to a machine in which a method or device according to the invention is used.

[0004] In robotics and automation technology in general, measuring the position of rotary or translatory axes or servo axes, which are also commonly interpreted as joints, is of great importance. A challenge, particularly with mobile robots, is the integration of angle encoders or linear measuring systems into the mechanical structure due to the extremely limited installation space. If translatory movements are realized using a spindle drive, assuming that the spindle drive has only minimal mechanical play, it is possible, for example, to also measure the linear displacement using absolute angle encoders.

[0005] Absolute encoders designed as so-called multiturn encoders are convenient to use. These include an angle measuring device for 0° to 360° and a counter for the number of rotations performed. However, these are usually equipped with batteries or additional electronics to achieve multiturn capability, resulting in packaging disadvantages or additional maintenance requirements.

[0006] Very compact angle encoders, which can be integrated even in very small installation spaces, are available in the form of single-turn absolute encoders. Multi-turn capability can also be replicated.

[0007] In this context, 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. This method stores the number of complete revolutions of the single-turn absolute encoder's axis. In angle encoders with detection sectors, particularly angle encoders with a linear output voltage, it can be observed that, due to parasitic low-pass filter behavior, the transition from one detection sector to another is occasionally not clearly recognizable. Therefore, the detection threshold cannot be set to the value of the maximum angle change per step or just above it, but rather to half the sector size of the detection sector, i.e., to 45° for detection sectors with a sector size of 90°.

[0008] A similar problem can also occur with linear measuring systems whose measurement consists of a mixture of incremental and absolute components.

[0009] It is an object of the invention to provide solutions for operating a measuring sensor for a rotary or linear movement which enable improved detection of transitions between detection sections.

[0010] This object is achieved by a method having the features of claim 1, by a computer program with instructions according to claim 8, by a device having the features of claim 9, and by a machine according to claim 10. Preferred embodiments of the invention are the subject of the dependent claims.

[0011] According to a first aspect of the invention, a method for operating a rotary or linear motion encoder, the encoder having a number of detection sections, comprises the steps of:

[0012] - Recording a measured value of a detection section;

[0013] - Determining a confidence value from the acquired measurement and a previously acquired measurement;

[0014] - Determining a current position value based on at least the acquired measurement value, the previously acquired measurement value and the confidence value; and

[0015] - Output the determined current position value.

[0016] According to a further aspect of the invention, a computer program comprises instructions which, when executed by a computer, cause the computer to perform the following steps for operating a rotary or linear motion encoder having a number of detection sections:

[0017] - Detecting a measured value of a detection section; - Determining a confidence value from the detected measured value and a previously detected measured value;

[0018] - Determining a current position value based on at least the acquired measurement value, the previously acquired measurement value and the confidence value; and

[0019] - Output the determined current position value.

[0020] The term "computer" should be understood broadly. In particular, it also includes control units, embedded systems, and other processor-based data processing devices.

[0021] The computer program may, for example, be made available for electronic retrieval or stored on a computer-readable storage medium.

[0022] According to a further aspect of the invention, a device for operating a rotary or linear movement encoder having a number of detection sections comprises:

[0023] - a signal processing unit for detecting a measured value of a detection section;

[0024] - a computing unit for determining a confidence value from the recorded measurement value and a previously recorded measurement value and for determining a current position value based on at least the recorded measurement value, the previously recorded measurement value and the confidence value; and

[0025] - an output unit for outputting the determined current position value.

[0026] The inventive solution uses a filter based on a confidence interval for the acquired measured variables. Depending on the confidence value, instead of directly transferring the measured variable, the filter reverts to the acquired measured variable from the previous step, thus providing an estimated value. This achieves increased robustness with a manageable computational effort.

[0027] According to one aspect of the invention, the confidence value is determined based on the difference between the acquired measured variable and the previously acquired measured variable. Using the difference has the advantage that the confidence value depends on the change in the measured variable, not on the absolute value of the measured variable.

[0028] According to one aspect of the invention, the confidence value is determined using a function that provides a high confidence value for a difference between 0 and a lower limit and for a difference between an upper limit and a section size of the detection section, and that provides a lower confidence value for a difference between the lower limit and the upper limit. This ensures that the function only provides a high confidence value, e.g., a value of 1 for full confidence, when the change is small. All values ​​between the two limits are less trustworthy.

[0029] According to one aspect of the invention, when determining the current position value, a current position change is determined from a previous position change and the difference. For example, the current position change can be determined as the 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 change is thus an estimated value that reflects the confidence in the sensor values. The current position value can then be easily determined as the sum of a previous position value and the current position change.

[0030] According to one aspect of the invention, in the case of a high confidence value, the current position value and the current position change are corrected based on a moving average. When the confidence value is high again, for example, at 1, the sensor value is iterated. For this purpose, the newly calculated position value and the value of the position change are corrected based on a moving average. This step is advantageous because, for measured values ​​with a reduced confidence value, e.g., a confidence value less than 1, the integrating position calculation leads to an error. After a few steps, the position value and the confidence value are then adjusted again.

[0031] A method according to the invention or a device according to the invention is particularly advantageously used in a machine, in particular in a means of transport or an industrial machine. The means of transport can be, for example, a motor vehicle, e.g., a passenger car or a commercial vehicle. In principle, the solution according to the invention is applicable in all situations in which angle or length detection is required, e.g., in actuating devices for flaps, valves, doors, etc. The industrial machine can be, for example, a robot or another automation system in which angle or length detection is required.

[0032] Further features of the present invention will become apparent from the following description and the appended claims, taken in conjunction with the figures. Figure 1 schematically shows a method for operating a sensor;

[0033] Fig. 2 shows a first embodiment of a device for operating a measuring sensor;

[0034] Fig. 3 shows a second embodiment of a device for operating a measuring sensor;

[0035] Fig. 4 schematically represents, as an example of a machine, a means of transport in which a solution according to the invention is implemented;

[0036] Fig. 5 shows schematically an angle sensor with an analog output signal;

[0037] Fig. 6 shows an example of an algorithm for implementing an inventive

[0038] procedure;

[0039] Fig. 7 shows exemplary functions for determining a confidence value; and

[0040] Fig. 8 shows results of a signal evaluation by the algorithm from Fig. 6.

[0041] To better understand the principles of the present invention, embodiments of the invention are explained in more detail below with reference to the figures. It is understood that the invention is not limited to these embodiments and that the described features may also be combined or modified without departing from the scope of the invention as defined in the appended claims.

[0042] Fig. 1 schematically shows a method for operating a measuring sensor with a number of detection sections. In a first step, a measured variable of a detection section is detected 10. A confidence value is determined 11 from the detected measured variable and a previously detected measured variable, e.g., based on the difference between the detected measured variable and the previously detected measured variable. To determine 11 the confidence value, a function is preferably used that provides a high confidence value for a difference between 0 and a lower limit and for a difference between an upper limit and a section size of the detection section, and that provides a lower confidence value for a difference between the lower limit and the upper limit. A current position value is then determined 12 based at least on the detected measured variable, the previously detected measured variable, and the confidence value.For this purpose, a current position change can be determined from a previous position change and the difference between the recorded measurement value and the previously recorded measurement value.

[0043] For example, the current position change can be determined as the 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 a 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 be corrected beforehand based on a moving average.

[0044] Fig. 2 shows a simplified schematic representation of a first embodiment of a device 20 for operating a measuring sensor 1 for a rotary or linear movement, which has a number of detection sections. The device 20 has an input 21, via which a signal processing unit 22 detects a measured variable Mj of a detection section. A computing unit 23 is configured to determine a confidence value Ci from the detected measured variable Mj and a previously detected measured variable MM, for example, based on the difference between the detected measured variable Mj and the previously detected measured variable M.To determine the confidence value Ci, a function is preferably used that provides a high confidence value Ci for a difference between 0 and a lower limit and for a difference between an upper limit and a section size of the detection section, and that provides a lower confidence value Ci for a difference between the lower limit and the upper limit. The computing unit 23 is also configured to determine a current position value based at least on the detected measured variable Mi, the previously detected measured variable MM, and the confidence value Ci. For this purpose, a current position change can be determined from a previous position change and the difference between the detected measured variable Mi and the previously detected measured variable MM.For example, the current position change can be determined as the weighted sum of the previous position change, weighted by the complement of the confidence value Ci, and the difference, weighted by the confidence value Ci. The current position value Wi can then be determined as the sum of a previous position value and the current position change.

[0045] An output unit 24 is configured to output the determined current position value Wi via an output 27 of the device 20. In the case of a high confidence value, the current position value and the current position change can be corrected beforehand by the computing unit 23 based on a moving average. The signal processing unit 22, the computing unit 23, and the output unit 24 can be controlled by a control unit 25. Settings of the signal processing unit 22, the computing unit 23, the output unit 24, or the control unit 25 can be changed via the user interface 28 if necessary. The data generated in the device 20 can be stored in a memory 26 if necessary, for example, for later evaluation or for use by the components of the device 20.The signal processing unit 22, the arithmetic unit 23, the output unit 24, and the control unit 25 can be implemented as dedicated hardware, for example, as integrated circuits. Of course, they can also be partially or completely combined or implemented as software running on a suitable processor, for example, a GPU or a CPU. The input 21 and the output 27 can be implemented as separate interfaces or as a combined bidirectional interface.

[0046] Fig. 3 shows a simplified schematic representation of a second embodiment of a device for operating a measuring sensor for a rotary or linear movement, which has a number of detection sections. The device 30 has a processor 32 and a memory 31. For example, the device 30 is a computer or a control unit. Instructions are stored in the memory 31 which, when executed by the processor 32, cause the device 30 to carry out the steps according to one of the described methods. The instructions stored in the memory 31 thus embody a program executable by the processor 32 which implements the method according to the invention. The device 30 has an input 33 for receiving information, for example information about operating actions of a user of the machine. Data generated by the processor 32 are provided via an output 34.In addition, they can be stored in memory 31. The input 33 and the output 34 can be combined to form a bidirectional interface.

[0047] The processor 32 may include one or more processor units, such as microprocessors, digital signal processors, or combinations thereof.

[0048] The memories 26, 31 of the described embodiments can have both volatile and non-volatile storage areas and can comprise a wide variety of storage devices and storage media, for example hard disks, optical storage media, or semiconductor memories. Fig. 4 schematically illustrates, as an example of a machine 40, a means of transport in which a solution according to the invention is implemented. In this example, the means of transport is a motor vehicle. In this example, the motor vehicle has an actuating device 41 for valves. The actuating device 41 is provided with a measuring sensor 1. For operating the measuring sensor 1, the motor vehicle has a device 20 according to the invention.Further components of the motor vehicle include an infotainment system 42 with a display device 43, a number of assistance systems 44, an environmental sensor system 45 for acquiring environmental information, such as cameras, radar sensors, lidar sensors, or ultrasonic sensors, and a data transmission unit 46. The assistance systems 44 can access the measured values ​​of the sensor 1 as needed. Using the data transmission unit 46, for example, a connection to a backend can be established, e.g., for transmitting settings or retrieving updated software for the components of the motor vehicle. A memory 47 is provided for storing data. Data exchange between the various components of the motor vehicle takes place via a network 48.

[0049] In the following, further details of the solution according to the invention will be shown with reference to Fig. 5 to Fig. 9.

[0050] Fig. 5 schematically shows an angle encoder, i.e., a rotary encoder 1, with an analog output signal. The angle encoder has, for example, four detection sections S1-S4, i.e., four sectors with an angular range of 90° each. However, other configurations are also possible, e.g., configurations with semicircular sections or a full circle. The detection sections S1-S4 each provide a linear analog output signal, in this example, a voltage between 0 mV and 5000 mV.

[0051] Fig. 6 shows an example of an algorithm for implementing a method according to the invention. In this example, a measurement angle is determined using the angle encoder from Fig. 5. The pseudocode shown therefore refers to a sector size of the angle encoder of 90°. Whenever 90° or 45° is used as an operator in the pseudocode, the sector size or half the sector size is generally used there. After starting in block 100, the raw value (voltageRaw) of the voltage is read in the first block 110, and a raw angle (angleValueRaw(i)) is calculated from it. In addition, the difference (delta_alpha(i)) between the raw angle and the previously determined raw angle is calculated. The difference is divided into absolute value (abs_delta_alpha(i)) and 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 can be selected.A subsequent comparison block 120 checks whether the difference is greater than half the sector size. If this is the case, the angular step is considered a safe sector transition, and the difference is initially reduced by the sector size in block 130. In any case, the difference between magnitude and sign is then restored in block 140. In the following block 150, the angular step (stepAngle(i)) is estimated as the evaluated sum of the previous angular step, evaluated by the complement of the confidence value, and the current difference, evaluated by the confidence value. The current value for the angle (angleValueSens(i)) is then the sum of the last value of the angle and the angular step. This value lies within the total possible angular range between a minimum angle and a maximum angle. The next query in block 160 checks whether the confidence value is equal to 1. If not, the calculation ends.If so, the newly calculated angle and the angle step are corrected based on a moving average in block 170. This step is advantageous because the integrating angle calculation leads to an error for measured values ​​with a confidence value less than 1. Before the moving average is calculated, the current detection section (segSens) is first determined. After a few steps, the value of the angle and the angle step are adjusted again. The algorithm finally ends with block 180.

[0052] Fig. 7 shows example functions for determining a confidence value. The confidence value Ci is shown as a function of the absolute value of the difference Dj between the acquired measurement and the previously acquired measurement. In this example, this is the difference (abs_delta_alpha(i)) between the raw angle and the previously determined raw angle. Generally, the functions return the value '1', meaning full confidence, if the difference is small (0°...Gi or G2...90°). 0 ). All values ​​in between are less trustworthy. The range G2...90 0 corresponds to a sector transition. The course of the solid line between the limit values ​​G1 and G2 can be described, for example, by a fourth power. Such a function delivers very robust results. Alternatively, a linear course can be used, as indicated by the dashed line.

[0053] Fig. 8 shows the results of a signal analysis using the algorithm from Fig. 6. Fig. 8a) shows the time course of the raw voltage value (voltageRaw). Fig. 8b) shows the corresponding course of the raw angle (angleValueRaw), the absolute value (abs_delta_alpha) of the difference between the raw angle and the previously determined raw angle, and the angle step (stepAngle). Fig. 8c) shows the course of the current detection section (segSens), calculated once without filtering and once with filtering, as well as the course of the confidence value (conf_val). Fig. 8d) finally shows the time course of the angle (angleValueSens), calculated once without filtering and once with filtering. As can be clearly seen, the direct transfer of the measured values ​​in the area of ​​a sector transition can lead to a large jump in the angle. The inventive filtering of the values ​​significantly reduces this jump.The filtering only has a significant effect in a small temporal window where the confidence value deviates from ,T. The two curves then quickly converge again.

[0054] List of reference symbols

[0055] 1 sensor

[0056] 10 Recording a measured value

[0057] 11 Determining a confidence value

[0058] 12 Determining a current position value

[0059] 13 Output of the determined current position value

[0060] 20 Device

[0061] 21 Entrance

[0062] 22 Signal processing unit

[0063] 23 Computing unit

[0064] 24 output unit

[0065] 25 Control unit

[0066] 26 storage

[0067] 27 Exit

[0068] 28 User interface

[0069] 30 Device

[0070] 31 storage

[0071] 32 processor

[0072] 33 Entrance

[0073] 34 Exit

[0074] 40 machine

[0075] 41 Adjusting device

[0076] 42 Infotainment system

[0077] 43 Display device

[0078] 44 Assistance system

[0079] 45 Environmental sensors

[0080] 46 Data transmission unit

[0081] 47 storage

[0082] 48 Network

[0083] 100 - 180 program steps

[0084] Ci confidence value

[0085] The difference

[0086] Gi Lower limit G2 Upper limit

[0087] Mj measurement quantity

[0088] Sj detection section

[0089] SG section size

[0090] Wi position value

[0091] WSi position change

Claims

Patent claims 1. A method for operating a measuring sensor (1) for a rotary or linear movement, wherein the measuring sensor has a number of detection sections (Sj), comprising the steps: - detecting (10) a measured variable (Mj) of a detection section (Sj); - determining (11) a confidence value (Cj) from the acquired measurement value (Mj) and a previously acquired measurement value (Mn); - determining (12) a current position value (W) based on at least the acquired measurement value (Mj), the previously acquired measurement value (MM) and the confidence value (Ci); and - Output (13) of the determined current position value (Wj).

2. Method according to claim 1, wherein the confidence value (Ci) is determined on the basis of the difference (Di) of the detected measured variable (Mi) and the previously detected measured variable (M ) (11).

3. The method according to claim 2, wherein the confidence value (Ci) is determined (11) by means of a function (F) which provides a high confidence value for a difference (Di) between 0 and a lower limit value (Gi) and for a difference (Di) between an upper limit value (G2) and a section size (SG) of the detection section (Si), and which provides a lower confidence value for a difference (Di) between the lower limit value (G1) and the upper limit value (G2).

4. Method according to claim 2 or 3, wherein when determining (12) the current position value (W) from a previous position change (WS ) and the difference (Di) a current position change (WSi) is determined.

5. The method according to claim 4, wherein the current position change (WSi) is determined as the weighted sum of the previous position change (WS ), weighted by the complement of the confidence value (Ci), and the difference (Di), weighted by the confidence value (Ci).

6. The method according to claim 5, wherein the current position value (Wj) is determined (12) as the sum of a previous position value (WM) and the current position change (WSi).

7. Method according to one of claims 4 to 6, wherein in the case of a high confidence value (Cj) the current position value (Wj) and the current position change (WSj) are corrected on the basis of a moving average.

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

9. Device (20) for operating a measuring sensor (1) for a rotary or linear movement, the measuring sensor having a number of detection sections (Sj), comprising: - a signal processing unit (22) for detecting (10) a measured variable (Mj) of a detection section (Sj); - a computing unit (23) for determining (11) a confidence value (Ci) from the detected measured variable (Mj) and a previously detected measured variable (MM) and for determining (12) a current position value (Wj) on the basis of at least the detected measured variable (Mj), the previously detected measured variable (M ) and the confidence value (Ci); and - an output unit (24) for outputting (13) the determined current position value (W).

10. Machine (40), characterized in that the machine (40) has a device (20) according to claim 9 or is designed to carry out a method according to one of claims 1 to 7 for operating a measuring sensor (1) for a rotary or linear movement.

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