A method for an industrial object in an industrial system

Abstract

The present invention relates to a method for modeling an industrial object in an industrial system, the method including obtaining measurement data pertaining to a measurement of at least in parts a physical state of the object as well as time data pertaining to a point in time of the measurement of the physical state of the object, and based on a model of the object considering the measurement data and the time data, determining time-adjusted data pertaining to the physical state of the object reflective of a latency relative to the point in time of the measurement.

Description

[0001] A method for an industrial object in an industrial system

[0002] Technical field

[0003] The invention concerns a (computer-implemented) method for for handling measurement data pertaining to an industrial object in an industrial system, a data processing apparatus, a computer program, a control method, a control unit and an industrial system comprising the data processing apparatus and / or control unit.

[0004] Background

[0005] Real-time, fixed-frequency control systems are known, wherein measurements are performed at a fixed time relative to the control loop. The time is defined by the controller (control unit), and the delay (latency) between the measurement and its use in the control unit may be compensated by the control unit to achieve high performance.

[0006] Optimal motor control often, e.g. in robotics and automation, may require high-voltage, high- current and / or high-frequency power signals for equipment, such as robots. These power signals are in close proximity to the low-voltage measurement signals used as feedback in the control loop, and they may cause significant disturbances in the measurement. Known solutions to this problem may include costly cabling and shielding solutions to isolate the measurement signals from the power signals and prevent disturbances in the measurement.

[0007] Thus, there is a need for improved handling of time-related aspects of measurements, e.g. improved prevention or reduction of distubances of measurement (data).

[0008] Summary of the invention

[0009] The present invention solves this problem and relates to a (computer-implemented) method for handling / using / processing measurement data pertaining to an industrial object in an industrial system, the method including obtaining measurement data pertaining to a measurement of at least in parts a physical state of the object as well as time data pertaining to a point in time of the measurement of the physical state of the object, and based on a model of the object considering the measurement data and the time data, determining / generating time-adjusted data pertaining to the physical state of the object reflective of a latency, relative to the point in time of the measurement (between the measurement and the use, e.g. in the model).

[0010] The invention also concerns a corresponding data processing apparatus, computer program, control method and a controller (control unit) as well as an industrial system.

[0011] Time-adjustment (or time-adaption) of the data and / or the measured physical state may mean to shift the data / measurement to a different timing, e.g. to the past or the future. E.g. time adjustment may allow for time-compensation, such as latency compensation. As such, the method is adaptive in terms of time, i.e. time-wise adaptive.

[0012] The idea underlying the invention may be, in one embodiment, consideration, e.g. compensation, of latency by means of a model of the object. For example, time-synchronized networking between the measurement and the control system / unit may be used, combined with a model of the system under consideration / control (industrical object), to compensate for (e.g. variable) latency between the measurement time and its use (e.g. in the control loop / unit).

[0013] The measurement system carrying out the measurement of the physical state of the object may optionally time the measurement accordingly (e.g. at an ideal moment in time), ideally without (substantially) degrading the performance of the control loop. In other words, the invention may be implemented to time a measurement to take place when the power signal disturbances are less severe. This changes the latency between when the measurement is performed and when it is used in the control unit, which, as such (if not compensated for) may degrade the control performance.

[0014] The invention may be seen, in one embodiment, as allowing the measurement system to control the timing of measurements, and for the controller to at least partially compensate the resulting (variable) latency in the measurements. The compensation may be done using a time- synchronized network to allow the (variable) latency to be quantified for each measurement, and a model (e.g. in the controller) which may at least partially compensate for the (variable) latency and predict the value of the measurement at any given time.

[0015] In prior art methods, the measurement latency may be assumed to be constant and may e.g. be compensated offline by tuning the controller.

[0016] The invention offers various improvements as to timing aspects in connection with measurements, in particular cost-effective embodiments. E.g. in robotics and automation, specifically in motor control, expensive cabling solutions may replaced to reduce measurement disturbances by the system of the invention. A high control performance may, by means of the invention, be maintained even in the presence of disturbances.

[0017] Latency may be defined as the period of time between the occurrence of a physical event (here: measurement of the physical state of the object and / or control action) till the “arrival” of a signal (data) indicative of the occurrence of the event (i.e. measurement) at a desired site (here: control unit and / or model).

[0018] The method of the invention may be carried out on a single computer or, in parts, on several computers.

[0019] Typical measurement intervals may be 10 ps to 1 ms, in particular 100 to 500 ps. Hence, between multiple measurements, the time may be between 10 ps to 1 ms, in particular 100 to 500 ps. The interval may be fixed or variable.

[0020] The invention is not limited to variable, i.e. flexible, irregular, latency applications. As such, the invention is also applicable for fixed, i.e. constant, latency applications.

[0021] The invention is not limited to event-based control and / or measurements, but may be applicable to fixed frequency control and / or measurements.

[0022] An object’s physical state may refer to the location of the object in space.

[0023] The model describes, at least in parts, the behavior of the object, in particular the physical state and the object’s configuration. By way of modelling, i.e. the model, the true behaviour of the object may be estimated / reflected. The physical state of the object does not need to be modeled in its entirety, but may at least partially be described by the model.

[0024] A control unit may be part of controller or may separately be provided. The control unit may be provided in the controller and / or the measurement system may be provided in the object, such as in a robot arm.

[0025] The following timestamped network protocols may be applied for a time-synchronized network, i.e. determination of the latency: IEEE 1588 (2019) and / or IEEE 802.1AS.

[0026] Optionally, based on the time-adjusted data, a control action for controlling an action of the object is determined. Optionally, based on the model of the object, the time-adjusted data is predictive of conditions of the object affecting a future / planned measurement, optionally disturbances during the future measurement.

[0027] Optionally, based on the model of the object, time-adjusted data indicative of a point in time for a future measurement is determined based on conditions of the object affecting the future measurement, optionally based on avoidance and / or reduction of disturbances during the future measurement.

[0028] Optionally, the time-adjusted data is predictive of a physical state of the object at a future moment in time considering a future / planned action of the object.

[0029] Optionally, the time-adjusted data indicates a correction of the measured physical state to at least partially compensate for the latency relative to the point in time of the measurement.

[0030] Optionally, multiple measurement data pertaining to multiple measurements, respectively, are obtained at variable time intervals relative to each other so that the latency per measurement is variable.

[0031] Optionally, the latency, more optionally the variable latency per measurement, is quantified by means of the point in time of the measurement.

[0032] Optionally, the model includes modelling the object dynamics.

[0033] Optionally, the time-adjusted data reflective of latency compensation is obtained based on a time-synchronized network.

[0034] The invention is also directed to a data processing apparatus comprising means for carrying out the method of the invention.

[0035] The invention is also directed to a computer program comprising instructions which, when the program is executed by a computer, cause the computer to carry out the method of the invention.

[0036] The invention is also directed to a method for controlling an industrial object in an industrial system, wherein at least in parts a physical state of the object is measured as well as a point in time of the measurement of the physical state of the object is measured, based on a model of the object considering the measured physical state and the point in time, a time-adjusted physical state of the object is determined reflective of a latency relative to the point in time of the measurement, and based on the time-adjusted physical state, an action of the object is controlled.

[0037] The invention is also directed to a control unit configured to carry out the method of the invention.

[0038] The invention is also directed to an industrial system comprising the industrial object, in particular a robot and / or an automated object, and including the control unit and / or the data processing apparatus of the invention.

[0039] The present invention is not limited to industrial applications such as robotics. However, an advantage of robotics applications may be that in the field of robotics, appropriate models of the system are available, so that the robotics system can appropriately be reflected by means of a model. Additionally or alternatively, it may be advantageous if the topology is fixed, i.e. known.

[0040] The invention also relates to the following:

[0041] A computer-readable medium having stored thereon the computer program of claim 12. A control method of claim 13, optionally wherein: the model of the object predicts conditions of the object affecting the measurement, optionally disturbances during the future measurement; wherein a future point in time of the measurement is determined based on conditions of the object affecting the future measurement, optionally based on avoidance and / or reduction of disturbances during the future measurement; the time- adjusted physical state predicts a physical state of the object at a moment in time considering the action control; wherein the time-adjusted physical state corrects the measured physical state so as to at least partially compensate for the latency relative to the point in time of the measurement by way of the correction; wherein multiple measurements are carried out and the measurements are carried out at variable time intervals relative to each other so that the latency per measurement is variable; the point in time of the measurement is used to quantify the latency, optionally the variable latency per measurement; wherein the model includes modelling the object dynamics; wherein a time-synchronized network is used for latency determination.

[0042] Detailed embodiments and further advantages and features related to the present invention are described in the following, wherein these examples shall not be regarded as limiting the invention.

[0043] Brief description of the drawings Fig. 1 schematically shows occurrence of disturbances, measurements and control action over time, for a latency-fixed system.

[0044] Fig. 2 schematically shows steps performed in a system not having a model.

[0045] Fig. 3 schematically shows occurrence of disturbances, measurements and control action over time for a latency-variable system.

[0046] Fig. 4 schematically shows steps perfomed in a latency-variable system.

[0047] Detailed description

[0048] Fixed latency measurements, such as schematically shown in Fig. 1 , are known. Measurements take place at a fixed frequency, i.e. at constant time intervals. This is reflected in the second line of Fig. 1 by means of regularly distanced bars. Also, control actions, as reflected in the third line of Fig. 1 take place at regular intervals. Accordingly, the latency L, i.e. the delay between the measurement and the presence (arrival) of the signal indicative of the measurement, is constant. Accordingly, the delay, i.e. shift, between the bars in the second and third rows of Fig. 1 is predetermined and, hence, predictable. However, as indicated by thunders at bars no. 2, 3, 5, 6, 7 in line 2 of Fig. 1 pertaining to the measurements, these measurements are taken at points in time at which the measurement is disturbed, e.g. by way of other signals. Accordingly, at these points in time, the measurement (data) may be unreliable.

[0049] Fig. 2 shows a system configured for the schedule shown in Fig. 1 . This may be regarded as a (real-time control) system without latency compensation according to the prior art. A controller / control unit 1 includes a control action generator 2 generating a control action 3. The control action 3 is executed, such that the object 4 carries out the physical behavior / movement 5 in line with the control action 3. A measurement sytem 6 measures the physical state I movement 5 of the object 4, and sends measurement data 7 on the measured physical state to the control unit 1 .

[0050] For variable-latency measurements, the timing of the measurement relative to the “use” of the measured data in the controller 1 is variable, i.e. not fixed. In such cases, the measurement system 6 may time measurements such that disturbances are minimized, ideally avoided or at least reduced or changed. It may be predicted when disturbances will occur, and time measurements around them (e.g. postpone a future measurement); or sample at a higher frequency that what is required and post-process to mitigate the effects of the disturbance.

[0051] Such system is schematically shown in Figure 3, namely a (real-time control) system with latency compensation according to an embodiment of the invention. In this case, the measurement system 6 may e.g. predict when disturbances will occur and time measurements around the disturbances, i.e. by avoiding measurements during occurance of disturbances. Accordingly, in an embodiment of the invention, no measurements are taken as long as there is a disturbance. However, disturbances do not need to be avoided completely. It may be sufficient and in line with the invention to at least partially reduce an overlap between measurements and disturbances. The latency L is variable and may differ from measurement to measurement. Hence, L is, in the embodiment of Fig. 3, not fixed or predetermined.

[0052] The following differences relative to the system of Fig. 2 are identifiable, in the system of Fig. 4: Measurement data pertaining to the measured physical state 7 as well as a point in time of the measurement, i.e. an indication of the latency L, are measured. The measurement data pertaining to the physical state 7 as well as the latentcy L are sent (transmitted via the network) to the control unit 1 . The controller 1 additionally comprises an object model 8, by means of which the object 4 can be modelled. Based on the measurement data 7 and the model 8, time- adjusted, e.g. predicted measurement data 9 pertaining to a time-adjusted, e.g. predicted, physical state may be obtained.

[0053] To compensate for variable measurement latency L, the latency L for each individual measurement may need to be quantified for compensation. The latency L may be quantified by using a time-synchronized network, which has a common, global time. Measurements may be timestamped according to this global time, and the controller 1 may know exactly when they were taken (and thus the latency L).

[0054] With the measurement latency L quantified, it may be compensated using the (online) model 8 of the system. In some embodiments, measurement data is fused with the predicted value of the measurement data based on the control actions and a model of the system dynamics. For the invention, such models rely on having a variable measurement latency relative to the control action.

[0055] The model may compensate the measurement latency L for each individual measurement. A simple example may be to predict the measurement value (physical state of the object 4) based on the last known measurement by adding the measured or predicted rate of change of the measurement (e.g. axis speed) multiplied by the measurement latency L.

[0056] The control action 3 may also be fed into the model 8 for consideration by the model 8 for determination of the time-adjusted data.

[0057] For example, the model may be directed to a motor, allowing to predict the motor position by modelling the motor. The predicted measurement data may reflect what would be measured if a measurement were to be done at this moment in time. The control action generator may then control an action of the object based on the predicted measurement data.

[0058] The detailed description of the invention is provided with respect to the embodiments depicted in the drawings. Obvious variations and alternatives may occur to the skilled person, based on the summary of the invention. These variations and alternatives are part of the invention in so far they are covered by the appended claims.

Claims

Claims:1 . Computer-implemented method for handling measurement data pertaining to an industrial object (4) in an industrial system, the method including obtaining measurement data pertaining to a measurement of at least in parts a physical state of the object (4) as well as time data pertaining to a point in time of the measurement of the physical state of the object, based on a model (8) of the object considering the measurement data and the time data, determining time-adjusted data pertaining to the physical state (9) of the object reflective of a latency (L) relative to the point in time of the measurement.

2. Method of claim 1 , wherein, based on the time-adjusted data, a control action for controlling an action of the object is determined.

3. Method of claim 1 or 2, wherein the time-adjusted data is predictive of conditions of the object affecting a future measurement, optionally disturbances during the future measurement.

4. Method of claim 3, wherein, based on the model (8) of the object, time-adjusted data indicative of a point in time for a future measurement is determined based on conditions of the object (4) affecting the future measurement, optionally based on avoidance and / or reduction of disturbances during the future measurement.

5. Method of any of the preceding claims, wherein the time- adjusted data is predictive of a physical state of the object (4) at a future moment in time considering a future action of the object (4).

6. Method of any of the preceding claims, wherein the time- adjusted data indicates a correction of the measured physical state (4) to at least partially compensate for the latency (L) relative to the point in time of the measurement.

7. Method of any of the preceding claims, wherein multiple measurement data pertaining to multiple measurements, respectively, are obtained at variable time intervals relative to each other so that the latency (L) per measurement is variable.

8. Method of any of the preceding claims, wherein the latency (L), optionally the variable latency per measurement, is quantified by means of the point in time of the measurement.

9. Method of any of the preceding claims, wherein the model (8) includes modelling the object (4) dynamics.

10. Method of any of the preceding claims, wherein the time- adjusted data reflective of latency compensation is obtained based on a time- synchronized network.11 . Data processing apparatus comprising means for carrying out the method of any of the preceding claims.

12. Computer program comprising instructions which, when the program is executed by a computer, cause the computer to carry out the method of any of the preceding claims 1 to 11 .

13. Method for controlling an industrial object in an industrial system, wherein at least in parts a physical state of the object is measured as well as a point in time of the measurement of the physical state of the object is measured, based on a model of the object considering the measured physical state and the point in time, a time-adjusted physical state of the object is determined reflective of a latency relative to the point in time of the measurement, and based on the time-adjusted physical state (9), an action (3) of the object is controlled.

14. Control unit (1 ) configured to carry out the method of claim 13.

15. Industrial system comprising the industrial object (4), in particular a robot and / or an automated object, and including the control unit (1) of claim 14 and / or the data processing apparatus of claim 11.

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