Automated characterization of multi-input multiple-output (MIMO) force response problems using subsequent single-input multiple-output (SIMO) or single-input single-output (SISO) tests with embedded devices.

Abstract

A system and method for automated MIMO force response characterization of a device / structure under test. A SIMO exciter router operates to selectively couple excitation signals input to an exciter device, and sensor data indicative of sensed responses to the applied excitation forces are collected from a plurality of response sensors. The SIMO exciter router operates to collect sensor data for each of a plurality of different exciter-sensor combinations (i.e., sensor data is collected from each individual response sensor while an excitation force is applied by each individual exciter device). The sensor data is collected by a data acquisition system having a plurality of signal input channels each coupled to a different response sensor, or a sensor router is used to selectively couple each individual sensor output to a shared signal input channel of the data acquisition system.

Description

Technical Field

[0001] Background Art The present invention relates to a system and method for testing the response of a device or structure to an applied excitation (e.g., vibration) condition.

Summary of the Invention

Means for Solving the Problems

[0002] In one embodiment, the present invention provides a method for automatically evaluating the multi-input multi-output (MIMO) force response characteristics of a device or a test structure. A plurality of exciter devices and a plurality of response sensors are coupled to the test structure (either directly or indirectly via test fixtures). An exciter router operates to repeatedly couple an excitation signal input to each of the plurality of exciter devices to selectively apply an excitation force to the test structure by each individual exciter device. While the excitation force is being applied, sensor data is collected from the plurality of response sensors. Specifically, while the excitation force is being applied by the first exciter device, a first set of sensor data is collected from each of the plurality of response sensors, and while the excitation force is repeatedly being applied by each additional exciter device, subsequent sets of sensor data are collected from each of the plurality of response sensors. Then, a MIMO system response function is determined based on the collected sensor data. In some embodiments, the response sensor data is collected in parallel by a data acquisition system having multiple input channels, but in other implementations, the response sensor data is collected sequentially by operating a sensor router to repeatedly couple each individual response sensor to a single input channel of the data acquisition system.

[0003] In another embodiment, the present invention provides a test system for automated MIMO force response characteristic evaluation of a device or structure under test. The test system includes a plurality of exciter devices, a plurality of response sensors, a signal generator, an exciter router, a data acquisition system, and an electronic controller. The exciter router is configured to selectively couple excitation signals generated by the signal generator to each of the plurality of exciter devices in order to cause the exciter devices to impart excitation forces to the structure under test. The data acquisition system collects sensor data from each of the plurality of response sensors showing the detected response to the applied excitation forces. The electronic controller operates the exciter router to apply excitation signals to the first exciter device until a first set of sensor data is collected by the data acquisition system from each of the plurality of response sensors while the excitation signals are applied by the first exciter device. The electronic controller then operates the exciter router to apply the excitation signal to each additional exciter device until an additional set of sensor data is collected from each response sensor by the data acquisition system, while the excitation signal is repeatedly applied to each individual exciter device.

[0004] In some implementations, the data acquisition system includes multiple signal input channels, each coupled to a different response sensor, while in other implementations, the test system also includes a sensor router configured to selectively couple each individual sensor output to a shared signal input channel of the data acquisition system. In some implementations, an electronic controller is configured to determine the system response function for the structure under test by loading the sensor data collected for each of several different exciter sensor combinations into a system response function (SRF) matrix.

[0005] In other embodiments, the present invention provides a test system for automated MIMO force response characterization of a device or structure under test. The SIMO exciter router has an input channel coupled to receive an excitation signal input and a plurality of excitation signal output channels, each coupled to one of a plurality of exciter devices. An electronic controller is configured to control the SIMO exciter router so that it selectively applies excitation signal inputs to individual exciter devices while sensor data indicating the detected response to the excitation force applied to the structure under test by the individual exciter devices is collected from a plurality of response sensors. The electronic controller is configured to control the SIMO exciter router until sensor data is collected for each of a plurality of different exciter-sensor combinations, the sensor data collected for each of the different exciter-sensor combinations includes sensor data collected from a single response sensor while the excitation force is applied by a single exciter device. In some implementations, sensor data is collected by a data acquisition system having multiple signal input channels, each coupled to a different response sensor; in other implementations, the test system also includes a sensor router configured to selectively couple each individual sensor output to a shared signal input channel of the data acquisition system.

[0006] Other aspects of the present invention will become apparent from the detailed description and the accompanying drawings. [Brief explanation of the drawing]

[0007] [Figure 1A] This is a perspective view of a vibration testing system in a single implementation configuration. [Figure 1B] Figure 1A is a perspective view of the exciter device of the vibration testing system. [Figure 1C] Figure 1B is a cross-sectional view of the exciter device. [Figure 2] This is a graph of the frequency response function measured by the system shown in Figure 1A, expressed as a frequency-dependent acceleration function. [Figure 3] This is a schematic diagram illustrating the mathematical relationship between multi-input multiple-output (MIMO) system response function (SRF) measurements and the corresponding MIMO SRF matrix. [Figure 4] This is a block diagram of the control system for the test system shown in Figure 1A, which is configured to perform MIMO system vibration testing by sequentially acquiring and processing single-input multiple-output (SIMO) SRF data. [Figure 5] This is a block diagram of the control system for the test system shown in Figure 1A, which is configured to perform MIMO system vibration testing by sequentially acquiring and processing single-input single-output (SISO) SRF data. [Figure 6] This is a block diagram of the control unit for the control system shown in Figure 4 and / or Figure 5. [Figure 7] This is a flowchart illustrating a method for collecting and processing SISO SRF data using the control system shown in Figure 5 and the control unit shown in Figure 6. [Figure 8] This is a flowchart of a method for analyzing the quality of data collected while performing the method shown in Figure 7. [Figure 9] This table lists examples of data quality tests that may be performed as part of the method shown in Figure 8. [Figure 10] This is a graph of SRF reciprocity data collected during quality testing of the method shown in Figure 8. [Figure 11] Figure 8 shows a series of graphs of response consistency data collected during quality testing of the method. [Figure 12] Figure 8 is a graph of interface integrity criterion (ICC) data collected during quality testing of the method. [Figure 13A] This is a schematic diagram of an example of adjusting the applied excitation signal between the methods in Figure 7 and the quality test results of the method in Figure 8. [Figure 13B] Figure 8 shows graphs of the applied excitation signal before and after adjustment, based on the results of quality tests using the method. [Figure 13C] This graph shows the force spectrum of the applied excitation signal before and after adjustment of the excitation signal. [Figure 13D] This graph shows the response spectrum before and after adjustment of the excitation signal. [Modes for carrying out the invention]

[0008] Before describing in detail any embodiment of the present invention, it should be understood that the present invention is not limited in its application to the structural and arrangement details of the components described in the following description or shown in the following drawings. Other embodiments of the present invention are possible and can be carried out or implemented in a variety of ways.

[0009] Excitation tests may be performed on a device or structure (e.g., an automotive part) to model how a structure responds to different applied forces (e.g., sound, vibration, shock, etc.). In some implementations, the test may involve applying an excitation force to the device or structure at a first location and measuring the response at a second location. For example, a vibration force may be applied at the first location and acceleration measured at the other location. The difference between the applied excitation force and the measured response represents the system response. In other implementations, force excitation and response measurement may be juxtaposed to incorporate a drive point SRF measurement (e.g., the exciter device may be mounted on an accelerometer, and the accelerometer may be connected to the structure under test (e.g., see sensor 107A in Figure 4 below)).

[0010] Characterizing the structural mechanical properties of a machine is crucial for approaching problems of structural sound and vibration propagation with their full complexity (e.g., multipath and multi-degree-of-freedom (DoF) systems). While feasible for simple structures, accurate numerical modeling of structural and / or vibroacoustic properties remains challenging for most complex technical components and assemblies. Instead, in some implementations, their dynamic behavior can be experimentally characterized by system response function (SRF) measurements, as used, for example, during modal testing. The nature of the system response function (SRF) can be quite comprehensive and may include structural, acoustic, vibroacoustic, or other descriptions of the propagation characteristics of the structure (e.g., hydraulic (fluid) pressure response to applied force excitations). Furthermore, the SRF may be expressed in the time domain, mode domain, state-space domain, physical domain, or frequency domain. One specific example of a method for determining the SRF is the measurement of frequency response functions (FRFs), such as compliance, mobility, or acceleration.

[0011] Experimentally, FRF can be determined by employing some type of force excitation in a given input degree of freedom (DoF) and measuring the resulting system response in one or more spatial observer DoFs. For example, an instrumentation hammer (modal hammer) and / or a vibration shaker can be used as the excitation source to provide external force excitation to the structure, and kinematic sensors (e.g., displacement probes, velocity sensors, and / or accelerometers) are used to capture at least one system response for each excitation test. Other types of sensors may be used to account for other types of system responses, such as sound pressure, as in the case of vibroacoustic FRF measurements.

[0012] For simple FRF tests (e.g., when the setup and complexity of the apparatus are relatively simple and the number of SRFs to be measured is small), the experiment can be performed manually, for example, with all measuring devices set up before the first measurement and all FRFs being measured in parallel. Alternatively, in more sophisticated structures or cases where the availability of measuring devices is limited, the experiment may be performed in a “roving apparatus” manner in which at least some of the exciters and / or sensors are moved to different positions after each excitation test. The relevant measurement techniques may be referred to as “roving exciter (hammer, shaker)” or “roving sensor (accelerometer, etc.)” experiments. Roving measurement techniques are advantageous in terms of cost and / or the availability of the necessary equipment. These techniques can not only significantly reduce the number of exciters and / or sensors required, but can also be performed on low-channel-count DAQ systems. However, some drawbacks of roving measurement tests include: (1) increased measurement time and effort as the complexity of the structure under test increases; (2) introduction of experimental errors due to the need for repositioning instrumentation between different tests (e.g., consistent positioning of the instrument, proper mounting / application of force excitation, proper alignment of excitation / response DoF); and (3) increased susceptibility to errors during subsequent manual data processing steps, and the lack of automatic synchronization between data acquisition and data post-processing steps.

[0013] For these reasons, in some implementations, SRF testing in more advanced multi-input multi-output (MIMO) systems is performed in a partially or fully automated manner, with all necessary measuring equipment installed on the test structure before the start of the measurement. In some implementations, FRF measurements are then performed simultaneously for all responses and force excitation DoF. While simultaneous measurement significantly reduces data acquisition time, unfortunately, this reduction comes at the expense of higher equipment costs required for high-channel DAQ systems to acquire all force excitations and system responses in parallel using multi-reference FRF post-processing methods, as well as the flexibility to excite structures with arbitrary excitation functions (e.g., swept sine wave, random noise, shock, etc.).

[0014] In some implementations, such "automated" simultaneous FRF measurement techniques may also utilize a specifically designed excitation sequence, as well as related post - processing methods such as vibration testing using multi - reference random methods (e.g., burst random excitation) and / or multi - sine sweep excitation. These types of methods can be utilized in equipment - intensive experimental studies such as aircraft ground vibration tests where, for example, the measurement device is directly installed on the test structure and disassembled after the test is completed. Thus, the data collection time for "single - sample" SRF measurement is relatively short compared to the total test time, which includes measurement and equipment preparation time, data collection time, data post - processing steps, and the time to disassemble the measurement device after the test. Similar considerations are also valid for similarly sophisticated but dimensionally more compact structures such as automotive parts and / or component assemblies (e.g., electric power steering (EPS) systems, transmission gearboxes, engines, etc.). However, in automotive applications, vibration tests may need to be repeated on multiple components to evaluate the overall noise, vibration, and harshness ("NVH") performance for a statistically relevant number of test samples. These "multi - sample" SRF measurements would greatly benefit from improved SRF measurement techniques that can rapidly and efficiently collect high - quality SRF data by a fully automated method without requiring labor - intensive instrumentation steps and / or expensive DAQ systems to provide a sufficient number of separate measurement channels.

[0015] Figure 1A shows an example of an SRF test system 100. The fixture 101 includes two arms configured to hold the device / structure 103 under test. In the example in Figure 1A, the fixture 101 is configured to hold an electric power steering system for SRF testing. Multiple excitation units 105 are configured to apply excitation forces to the device / structure 103 in a controllable manner and are coupled to the device / structure 103 directly or indirectly by being coupled to the fixture 101, and the fixture is coupled to the device / structure 103. Similarly, multiple response sensors 107 (e.g., accelerometers) are also coupled (directly or indirectly) to the device / structure under test.

[0016] As shown in more detail in FIG. 1B, each excitation unit 105 in the example of FIG. 1A includes a vibration exciter 109 (i.e., a “shaker”) and a load cell 111. As shown in FIG. 1C, the vibration exciter 109 is a magnetic drive exciter device including a cylindrical body 113 having a pair of electromagnetic coils 115 coupled to the cylindrical body 113. A piston 117 (e.g., also referred to as a “table”) to which a permanent ring magnet 119 is attached is at least partially disposed within the cylindrical body 113 without being fixedly coupled to the cylindrical body 113. Thus, a controllably applied magnetic field by the electromagnetic coils 115 interacts with the permanent ring magnet 119 to cause movement of the cylindrical body 113 relative to the piston 117. For example, when one end of the piston 117 is coupled to the test device / structure 103 and an alternating current is applied to the electromagnetic coils 115, the resulting alternating magnetic field causes a corresponding alternating movement of the cylindrical body 113 relative to the piston 117, which in turn results in a controllable vibration force being applied to the test device / structure 103 via the piston 117. The amplitude and frequency of the applied vibration force can be adjusted and regulated by controlling the amplitude and frequency of the current applied to the electromagnetic coils 115, which controls the amplitude and frequency of the magnetic field applied by the electromagnetic coils 115 to the permanent ring magnet 119. The examples of FIGS. 1A - 1C illustrate the use of the vibration exciter 109, although in some implementations, other types of exciter devices may be used instead of or in addition to the vibration exciter 109. The exciter device may include, for example, a speaker, a rotating eccentric mass actuator, an electric motor, a solenoid actuator, a piezoelectric actuator, or any other mechanical or electromechanical device configured to apply a vibratory, pulsating, reciprocating, transient, or other dynamically changing force, such as any other drive mechanism capable of dynamically exciting a physical structure.

[0017] Therefore, an exciter device, such as a vibration exciter 109, is used to generate a “known” dynamic force input to the device / structure 103 under test, and the force / load generated by the excitation source and applied to the device / structure 103, as will be described in more detail below, can be used as a reference signal for calculating the system response function (SRF) in the data post-processing step. The actual dynamic force / load applied by the exciter device (e.g., vibration exciter 109) is measured, for example, using a load cell 111 coupled between the exciter device and the device / structure 103 (as shown in Figure 1B). In other implementations, other mechanisms for measuring the applied excitation force may be used, for example, including one or more force transducers embedded inside the excitation source. For example, the actual dynamic force excitations applied to the device / structure 103 under test may be determined by using other techniques and methods, including, for example, inverse measurement techniques (e.g., inverse force synthesis), model-based force reconstruction methods (e.g., analytical, numerical, experimental, and / or hybrid methods), or the measurement of other load indices (e.g., current, voltage, strain, etc.) mapped (e.g., mathematically) to the force / load excitation space. In the examples described herein, the term “load” is a generalization of the term “force” to describe other types of dynamic excitations that may be applied to the device / structure 103 under test, such as sound pressure (in the case of an acoustic exciter).

[0018] The response sensor 107 is configured to detect / determine the actual response of the device / structure 103 under test to the excitation of dynamic forces applied by one or more exciter devices (e.g., vibration exciter 109). In some implementations, the response sensor 107 can be considered a dynamic transducer mechanically coupled to the device / structure under test. The response sensor 107 measures how the device / structure 103 (and any testbench components coupled thereto, e.g., fixtures 101) respond to the excitation signal. The response sensor 107 provides signals and / or data representing the output response to a connected data acquisition system (as further described below). Depending on the type of system response function (SRF) determined, different types of sensors, including, for example, accelerometers and / or microphones, may be used. In the example in Figure 1A, the response sensor 107 includes an accelerometer. In some other implementations, the test system 100 may be configured to measure / determine the response of the device / structure 103 under test without mechanically coupled sensors, for example, by using non-contact sensors such as laser-based measuring devices. In some implementations, the response of the device / structure under test may be determined at several locations without physical instrumentation, for example, by using a system equivalent model mixture.

[0019] As shown in Figure 2, in some implementations, the frequency response function between two locations (e.g., the location of the vibration exciter 109 and the location of the response sensor 107) can be defined as "accelerance," or in other words, the ratio between the frequency domain representation of the measured acceleration response and the frequency domain representation of the applied dynamic force. Figure 2 shows the frequency response function as both its magnitude and phase as a function of frequency (i.e., a frequency-dependent acceleration function (A / F)).

[0020] As further shown in Figure 3, several different frequency response functions can be calculated for the device / structure under test by calculating the acceleration between different combinations of input (i.e., applied dynamic excitation force) and output (i.e., response acceleration). The schematic diagram on the left of Figure 3 shows a simplified example of a plate-like structure with multiple input forces (F) and multiple output responses (A). Each input and output provides other degrees of freedom. A complex network of SRFs is measured / determined to characterize the structure's ability to propagate structural propagation energy between input degrees of freedom (DoF) and output degrees of freedom (DoF). In this example, the test structure is assumed to be linear and time-invariant, and therefore SRF characterization can be performed simultaneously. Alternatively, SRF characterization can be performed as a series of subsequent measurements in which one excitation is applied at the input DoF at a time and the associated dynamic response is observed. In some implementations (as will be described in more detail below), the associated dynamic response of each input DoF is also measured once at a time (SISO), while in other implementations, multiple output DoFs are measured simultaneously (SIMO).

[0021] Figure 3 also shows an example of how a complete MIMO SRF matrix can be reconstructed from individual SISO or SIMO SRF experiments. In SISO experiments, all components of the MIMO matrix correspond to separate measurements, whereas in SIMO experiments, the entire column of the MIMO SRF matrix can be read simultaneously. Therefore, no additional assumptions are imposed regarding the force excitations used to achieve a suitable reference signal necessary to construct the mathematical SRF ratio defined in complex space.

[0022] Figures 4 and 5 show examples of systems configured to perform fully automated system response function (SRF) measurements, including structural and vibration-acoustic frequency response (FRF) measurements for advanced multi-input multi-output (MIMO) vibration problems. In particular, these systems are configured to perform advanced MIMO SRF measurements by sequentially performing single-input multiple-output (SIMO) data acquisition (as shown in Figure 4) and single-input single-output (SISO) SRF data acquisition (as shown in Figure 5). The acquired data is then reconstructed using post-processing routines to obtain complete MIMO SRF measurements by loading the data into a MIMO SRF matrix, for example, as shown in Figure 3.

[0023] In both examples (Figures 4 and 5), the test system includes a one-channel (SISO) signal generator 501 configured to provide continuous, transient, and / or other types of dynamic signals. The SISO signal generator 501 is coupled to a SISO power amplifier 503 configured to output appropriately tuned driver signals. The driver signals are then routed one at a time to each vibration exciter 109 by a SIMO exciter router 505. The SIMO exciter router 505 includes a controllable switching device and / or other control logic configuration configured to selectively couple the output from the SISO power amplifier 503 to a different of the multiple vibration exciters 109 during each vibration test in a series of vibration tests, while electronically isolating other unused vibration exciters 109 to ensure optimal signal / data tuning and quality. As described above, each vibration exciter 109 in this example is coupled to a load cell 111 to determine the actual dynamic load applied to the device / structure 103 under test by the “operable” vibration exciter 109.

[0024] All of the load cells 111 are communicatively coupled to the MISO load router 507, which is configured to electronically and / or digitally connect the “operable” load cell 111 (i.e., the load cell 111 currently coupled to the “operable” vibration exciter 109) to a single input channel of the data acquisition system 509 / 603, and to electronically isolate the other unused load cells 111. The MISO load router 507 helps to ensure optimal signal / data conditioning and quality while reducing the number of data acquisition input channels required for the data acquisition system 509 / 603.

[0025] During an SRF test using the system in Figure 4 or Figure 5, the operating vibration exciter 109 generates dynamic forces such that vibrations are applied to the device / structure 103 and any structures connected to it (e.g., fixtures 101). The applied structure-propagated energy is then propagated (and thereby radiated) through different paths of the coupled device / structure 103, causing a kinematic response at each of a plurality of response locations (each location provides an additional response DoF for the SRF experiment). The kinematic response at each different location is measured by the corresponding response sensor 107 of a plurality of response sensors 107. In the example in Figure 4, each response sensor 107 of the plurality of sensors is coupled to a different input channel of the data acquisition system 509, and thus the outputs of the plurality of response sensors 107 are measured in parallel with the measurement from a single load cell 111 during each data acquisition step. However, in the example in Figure 5, each response sensor 107 is coupled to the MISO sensor router 601. The MISO sensor router 601 is configured to electronically and / or digitally connect a single response sensor 107 to the data acquisition system 603 (when a numerical method is used to determine the response) and to electronically isolate other unused response sensors 107. Thus, multiple response sensors 107 can be selectively and controllably coupled to the same input channel of the data acquisition system 603, thereby reducing the number of input channels required. In other implementations, multiple MISO sensor routers 601 may be used to simultaneously measure responses from a subset of the response sensors 107 used. In such cases, the data acquisition system 603 may include multiple channels for measuring a subset of sensors 107 in parallel, but does not require a data acquisition system 603 with enough input channels to measure all sensors 107 simultaneously.

[0026] As shown in Figure 6, the controller 701 includes an electronic processor 703 and one or more non-temporary computer-readable memories 705. The memories 705 store data (e.g., data collected from sensors during an SRF experiment) and computer-executable instructions accessed and executed by the electronic processor 703 to provide the functionality of the controller 701, including the functions described herein. The controller 701 is communicatively coupled to the data acquisition systems 509 / 603 of the systems in Figures 4 and 5, respectively, and configured to receive response signal data collected during an SRF experiment. The controller 701 is also communicatively coupled to the SISO signal generator 501 and configured to generate control signals that define and / or modify signals generated by the SISO signal generator 501. The controller 701 is also communicatively coupled to the SIMO exciter router 505 and the MISO load router 507, and is configured to send control signals to the routers 505 and 507 to selectively control which vibration exciter 109 is coupled to receive excitation signals and which corresponding load cell 111 is coupled to the input channel of the data acquisition system 509 / 603. Similarly, in the system of Figure 5, the controller 701 is coupled to the MISO sensor router 601 and is configured to send control signals to the MISO sensor router 601 to selectively control which response sensor 107 is coupled to the input channel of the data acquisition system 509 / 603.

[0027] Figure 7 shows how the controller 701 operates the system in Figure 5 to perform a multi-input multiple-output (MIMO) system vibration test by sequentially executing multiple single-input single-output (SISO) data acquisition and processing routines. The controller 701 causes the SISO signal generator 501 to generate an excitation signal (step 801). Next, the controller causes the SIMO exciter router 505 to couple the excitation signal to the first vibration exciter 109 and the MISO load router 507 to couple the first load cell 111 to the load cell input channel of the data acquisition system 603 (step 803). Similarly, the controller causes the MISO sensor router 601 to couple the first response sensor 107 to the response input channel of the data acquisition system 603 (step 805).

[0028] When the first vibration exciter 109 is coupled to receive an excitation signal, and the first load cell 111 and the first response sensor 107 are coupled to their respective input channels in the data acquisition system 603, the controller 701 begins to collect and store data from the data acquisition system (step 807). In some implementations, the controller 701 is configured to use a trigger mechanism to wait until one or more predetermined conditions are met before recording the received data. The trigger may be used to control data acquisition based on the detection of specific events in applied or detected vibrations or other types of signals. Examples include exceeding a certain force level or vibration level when excitation is applied with an impact hammer or shaker during a modal test.

[0029] In some implementations, the data acquisition system 603 is configured to utilize a trigger mechanism so that data acquisition and processing do not start (or stop) until some signal level (e.g., voltage) is detected in the input channel. After the trigger is prepared, the controller 701 is initialized to wait for a signal event (e.g., a rising flank of the trigger signal exceeding 50% of the maximum channel range) to occur before acquiring / storing data, and / or to continue storing data received from the data acquisition system 603 until a predetermined stop condition is met. In some implementations, the stop condition is defined as a duration (e.g., the controller 701 stores 5 seconds of data from the time the signal event is detected) or other stop trigger criteria (e.g., the falling flank of the trigger signal falls below 50% of the maximum channel range). In some implementations, the trigger can be configured to automatically re-prepare after each trigger so that several measurements can be performed sequentially (e.g., to automate the aggregation and storage of multiple measurements).

[0030] In some implementations, the controller 701 is configured to utilize a trigger controlled based on the ability of the device / structure 103 under test to vibrate in response to applied vibrations. For example, it may take some time for the device / structure 103 under test to respond sufficiently linearly to the applied excitation. Therefore, if data acquisition is started simultaneously with the application of the excitation signal to the vibration exciter 109, high-quality SRF data will not be provided. Instead, the trigger start event may be configured to delay data acquisition relative to the excitation start time, thus giving the device / structure 103 more time to respond before the measurement begins. The same applies to the trigger stop of the measurement. If the measurement is stopped simultaneously with the disconnection of the vibration exciter 109 from the excitation signal, the structure may still not be able to respond to the latest excitation signal. Instead, in some implementations, the controller 701 may be configured to stop the measurement while the excitation signal is still applied to the vibration exciter 109. This stop condition trigger also prevents sudden starting or nonlinear behavior of the vibration exciter 109 during stopping from completely impairing the measurement. In some implementations, synchronous triggering may be performed automatically by control logic based on excitation type, frequency range, or other test-specific criteria.

[0031] Returning to the method in Figure 7, after the data from the coupled response sensors is read and stored in memory 705, the controller 701 increments the MISO sensor router 601 to couple the next response sensor 107 to the response input channel of the data acquisition system 603 (step 805). Thus, this process of collecting response sensor data (step 807) and incrementing the MISO sensor router 601 (step 805) is repeated until sensor data is acquired from each response sensor 107 while excitation signals are applied by the same individual vibration exciters 109 (step 813). After sensor data has been collected by all response sensors 107 in the sequence (step 813), the controller 701 increments the SIMO exciter router 505 and the MISO load router 507 (step 803) to apply excitation signals to different vibration exciters 109. In this example, as the SIMO exciter router 505 and MISO load router 507 are incremented to apply excitation signals to different vibration exciters 109, the increment of the MISO sensor router 601 is reset to acquire sensor data from the first sensor in the sequence. This process continues until excitation signals have been applied to all vibration exciters 109 and sensor data has been recorded from each response sensor 107 while the excitation signals are being applied to the vibration exciters 109.

[0032] For example, consider a configuration in which three vibration exciters 109 and three response sensors 107 are coupled to the device / structure 103 under test. The controller 701 applies an excitation signal to the first vibration exciter 109 and collects sensor data from each of the three response sensors 107. Next, the controller 701 applies an excitation signal to the second vibration exciter 109 and again collects sensor data from each of the three response sensors 107. Finally, the controller 701 applies an excitation signal to the third vibration exciter 109 and again collects sensor data from each of the three response sensors 107. Thus, the controller 701 acquires nine different sensor data sets, one for each possible different combination of vibration exciters 109 and response sensors 107.

[0033] While the excitation signal is being applied to the last vibration exciter 109 in the sequence (step 819), sensor data is recorded for all response sensors 107 in the sequence (step 813). Then, one or more post-processing routines are applied to the collected data (step 821) to reconstruct and / or update the relevant MIMO SRF model / measurements that represent the overall dynamic behavior of the apparatus / structure 103 under test. For example, in some implementations, the controller 701 is configured to generate a MIMO SRF matrix using a frequency response function (FRF) for each different combination of vibration exciter 109 / load cell 111 and response sensor 107, as shown in Figure 3 above.

[0034] In some implementations, to ensure consistently high data quality, the data acquisition system (DAQ) works with the controller 701 to receive appropriate parameter indications before each individual measurement (or, in some implementations, before each group or sequence of measurements). The DAQ itself may be configured to provide advanced functions (formulas / algorithms) for appropriately adjusting the individual transducers (e.g., load cells 111 and response sensors 107) connected to each DAQ measurement channel. In some implementations, the DAQ provides a function to automatically adjust the range setting based on the "intensity" of the incoming measurement signal. This process may be referred to as "auto-ranging" and, in some implementations, is fully automated by the DAQ so that it is performed immediately before the measurement is taken. This can be done, for example, by operating one or more exciter devices 109 under conditions that generate the highest vibration level for a certain period (e.g., several seconds) while detecting and adjusting the connected sensor signals to prevent undesirable overloads (clipping). The purpose of parameterization procedures such as "auto-ranging" is to maximize the sensitivity of the measurement chain (transducers, cables, DAQ) without adversely affecting data quality. For example, in some implementations, the DAQ system is configured to measure a ±5V input signal (discretized with 24 bits) corresponding to the vibration amplitude (e.g., 10 m / s²). When the vibration amplitude is small (e.g., 1 m / s²), the effective range observed by the DAQ decreases to ±1V (auto-ranging). In this case, the 24-bit resolution remains equivalent for higher measurement accuracy (e.g., a clearer distinction between the signal of the measuring device and the sensitivity threshold). In some implementations, the DAQ features a communication and / or control interface that enables communication with other types of devices via compatible protocols such as serial bus, Ethernet, USB, or other communication interfaces.

[0035] In some implementations, the controller 701 is also configured to analyze data received from the load cell 111 and / or response sensor 107 to determine whether the acquired data meets specific data quality criteria. In response to determining that the acquired data for a particular response sensor 107, load cell 111, or various combinations thereof does not meet the data quality criteria, the controller 701 is configured to repeat data acquisition for one or more combinations of the vibration exciter 109 and response sensor 107. In some implementations, the controller 701 may repeat data acquisition by applying the same excitation signal to the vibration exciter 109 and acquiring data from the response sensor 107. In some implementations, the controller 701 may be configured to adjust the excitation signal applied to the vibration exciter 109 in addition to, or instead of, repeating data acquisition with the same excitation signal previously applied.

[0036] For example, as shown in the figure, the controller 701 may be configured to apply one or more quality tests (step 809) to the collected sensor data after each sensor reading step (step 807). As will be described in more detail below, in some implementations the quality tests may be designed to analyze data for individual vibration exciter 109 / response sensor 107 combinations, and in other implementations the quality tests may be designed to analyze data for vibration exciter 109 / response sensor 107 combinations against sensor data collected for other vibration exciter 109 / response sensor 107 combinations.

[0037] As shown in the example in Figure 7, in some implementations, the controller 701 is also configured to apply one or more quality tests (step 815) after collecting data from all sensors in a sequence to which excitation signals have been applied by the same vibration exciter 109, in addition to or instead of applying one or more quality tests after each response sensor reading (step 809). In other words, one or more quality tests (step 815) are applied before incrementing the SIMO exciter router 505 and MISO load router 507 (step 803) to apply excitation signals to the next vibration exciter 109 and connect the corresponding load cell 111 to the data acquisition system 603. Here again, in some implementations, in response to the collected data being determined to have failed one or more of the quality tests (step 815), the controller 701 is configured to adjust the excitation signal applied to the vibration exciter 109 (step 817) and to sequentially repeat data collection from one or more of the response sensors before proceeding to the next vibration exciter 109.

[0038] Furthermore, in some implementations, the controller 701 may be configured to apply one or more quality tests to the collected data after all SRF data has been collected (i.e., after data has been collected from all vibration exciter 109 / response sensor 107 combinations), in addition to or instead of quality checks performed after individual sensor readings and after each complete sequence of sensor readings. Furthermore, in some implementations, as described above, the controller 701 may be configured to send control signals to the SIMO exciter router 505, the MISO load router 507, and the MISO sensor router 601, thereby allowing any particular combination of vibration exciter 109 and response sensor 107 to be operated selectively. Thus, in some implementations, the controller 701 may be configured to analyze the acquired data after data has been collected for all combinations of vibration exciter 109 / response sensor 107, identify one or more combinations that do not meet the data quality criteria, and repeat data collection only for the combinations identified as having insufficient data quality. In some implementations, data acquisition for these insufficient combinations is performed by adjusting the excitation signal, operating the SIMO exciter router 505 to couple the adjusted excitation signal to the identified vibration exciter 109 of the combination with insufficient data, operating the MISO sensor router 601 to couple the identified response sensor 107 of the combination with insufficient data to the response input channel of the data acquisition system 603, and then collecting data from the coupled response sensor 107. This process is then repeated for each combination identified as having insufficient data quality.

[0039] As described above, in some implementations, multiple data quality checks may be applied to the collected data simultaneously (i.e., after data has been collected from individual sensors, after data has been collected from the entire sequence of sensors, and / or after data has been collected from all vibration exciter 109 / response sensor 107 combinations). Figure 8 shows an example of how the controller 701 performs multiple different quality tests to apply to the collected data. After input data is received (e.g., from one or more load cells 111 and / or multiple response sensors 107) (step 901), the controller 701 applies a first signal quality test (step 903). If the collected data does not pass the first signal quality test (step 905), a first adjustment is applied to the excitation signal (step 907), and data acquisition is repeated (step 909). However, if the collected data passes the first signal quality test (step 905), the controller 701 proceeds to apply a second signal quality test (step 911). Here again, if the collected data does not pass the second signal quality test (step 913), a second adjustment is applied to the excitation signal (step 915), and data acquisition is repeated (step 909). However, if the collected data does pass the second signal quality test (step 913), the controller 701 proceeds to apply the third signal quality test (step 917). If the collected data does not pass the third signal quality test (step 919), a third adjustment is applied to the excitation signal (step 921), and data acquisition is repeated (step 909). However, if the collected data passes all three signal quality tests, the controller 701 proceeds to the next data acquisition step, or, if all data has been collected, the controller 701 proceeds to apply a post-processing routine applicable to the collected data (for example, to load into a MIMO SRF matrix) (step 923).

[0040] In some implementations, the controller 701 is configured to perform each test sequentially, proceeding to the second signal quality test only if the collected data passes the first signal quality test, and similarly, proceeding to the third signal quality test only if the collected data passes both the first and second signal quality tests. However, in other implementations, the controller is configured to perform each test in parallel, proceeding to the second signal quality test regardless of whether the collected data passes the first signal quality test (as shown by the dashed line between steps 907 and 911 in Figure 8), and similarly, proceeding to the third signal quality test regardless of whether the collected data passes the first and / or second data quality tests (as shown by the dashed line between steps 915 and 917 in Figure 8). In some implementations, the controller 701 is configured to apply multiple signal quality tests as a combination of serial and parallel tests. For example, in some implementations, the controller 701 may be configured to perform both the first signal quality test (step 903) and the second signal quality test (step 911) on the collected data, regardless of whether the collected data passes the first or second signal quality test. However, it may be configured to perform the third signal quality test (step 917) only if the collected data passes the second signal quality test (or, in some implementations, only if the collected data passes both the first and second signal quality tests).

[0041] Finally, in some implementations, the controller 701 may be configured to apply a similar type of signal adjustment regardless of which signal quality test fails (for example, the first excitation signal adjustment (step 907), the second excitation signal adjustment (step 915), and the third excitation signal adjustment (step 921) are similar types of signal adjustments). However, in other implementations, the controller 701 may be configured to apply different types of signal adjustment to the excitation signal depending on which signal quality test fails. For example, the controller 701 may be configured to change the excitation signal from a random signal to a logarithmically swept signal (as described later with reference to Figure 13B) in response to the determination that the collected data fails the first signal quality test, and to apply a low-pass (or high-pass) filter to the excitation signal (as described later with reference to Figure 13C) in response to the determination that the collected data fails the second signal quality test. Therefore, in some implementations, in response to the determination that the collected data fails both the first and second signal quality tests, the controller 701 is configured to both (1) change the excitation signal to a logarithmically swept signal and (2) apply a low-pass (or high-pass) filter to the logarithmically swept excitation signal.

[0042] In various implementations, data quality testing (e.g., signal quality testing in the example in Figure 8) may include data processing and quality assurance steps in which the data quality of each individual SIMO or SISO experimental sequence is verified, each individual SIMO or SISO experiment is converted into some kind of SRF, each SRF is temporarily placed into one or more sub-MIMO matrices, and / or the data quality of the entire MIMO matrix (or multiple sub-MIMO matrices) is verified. In implementations in which each SRF is temporarily placed into one or more sub-MIMO matrices, the controller 701 may also be further configured to perform additional data transformation, manipulation, or extension routines, including numerical, model-based, and / or hybrid methods. Such techniques may include, for example, geometric reduction and / or transformation techniques (e.g., finite difference approximation and virtual point transformation), data manipulation techniques that numerically modify the boundary conditions under which the SRF experiment was performed (e.g., dynamic substructuring for joining and separating), data dimensionality reduction and / or regularization techniques (e.g., principal component analysis, truncation, or Tychonov regularized singular value decomposition), and extension techniques that model additional data for degrees of freedom where physical measurements were not performed (e.g., location on the device / structure under test) (e.g., system equivalent model mixture (SEMM) techniques where experimental data are combined with other measured / simulated data). Several specific examples of metrics and calculations that may be used in various implementations to ensure high-quality experimental data during an automated SRF measurement process are outlined in the table in Figure 9. However, some implementations may include fewer calculations, metrics, and tests than those listed in the table in Figure 9, and some implementations may include other calculations, metrics, and tests in addition to or instead of those listed in the table in Figure 9.

[0043] In some implementations, the controller 701 is configured to perform data processing and quality assurance steps using additional data (e.g., data specific to the test setup). Such data may include, for example, geometric relationships between excitation DoF and response DoF (e.g., Euclidean distance, Euler angles, etc.), metadata related to the experiment, and / or metadata required for recording purposes (e.g., data required to set up the MIMO matrix).

[0044] In various implementations, the analysis results of the data processing and quality assurance steps applied by the controller 701 may or may not be provided to the user as feedback during the automated SRF measurement process (e.g., via the display screen of the user interface 707). In implementations where quality test feedback is provided to the user, the results may be summarized in various ways, for example, from a single numerical value to a sophisticated graphical representation of data quality, to help the user interpret individual and / or overall data quality. Figures 10, 11, and 12 show examples of mechanisms for displaying data quality feedback information to the user via the display screen of the user interface 707.

[0045] Figure 10 shows an example of a graph that may be displayed to the user via the display screen of the user interface 707, showing the SRF reciprocity between automated measurement locations as a single-value matrix representation. In the example in Figure 10, the relative darkness of each displayed square indicates the relative quality of the data (for example, darker squares represent higher quality data). In some implementations, this analysis is part of a set quality test (Figure 7, step 815).

[0046] Figure 11 shows an example of a series of graphs that may be displayed to the user via the display screen of the user interface 707, indicating a measure of response consistency. The top graph shows overall response consistency as a frequency spectrum, the middle graph shows individual specific response consistency as a frequency spectrum, and the bottom graph shows specific response consistency as a single value. In the graphs of Figure 11, values ​​closer to 100% indicate higher data quality. In some implementations, the controller 701 may be configured to display all three graphs of Figure 11 simultaneously on the screen, while in other implementations, the controller 701 may be configured to display only one or two of the graphs of Figure 11, and / or to display different graphs of Figure 11 selectively and interchangeably.

[0047] Figure 12 shows an example of a graph that may be displayed to the user via the display screen of the user interface 707, showing the interface integrity criterion (ICC) as a frequency spectrum. Values ​​close to 1 ("1") indicate frequencies that should be further analyzed if the MIMO system is well described and the measurement is valid.

[0048] As described above with reference to Figures 8 and 9, in some implementations, the controller 701 is configured to adjust the applied excitation signal in order to further improve data quality. In some implementations, the controller 701 is configured to attempt to apply an excitation signal that imparts a force input to the device / structure under test in order to obtain a desired vibration output that satisfies as many of the specified quality conditions as possible. Adjustments to the excitation signal may include, for example, (1) duration (longer measurements can provide clearer (e.g., less noisy) results due to averaging effects, but increase the total data acquisition time), (2) type (e.g., shock / transient excitation, burst / random excitation, pseudo-random excitation, swept sine wave, step sine wave, etc.), (3) magnitude (e.g., amplitude scaling of the entire signal or time / frequency-dependent amplitude scaling), (4) frequency content (e.g., frequency-dependent filtering / equalization (e.g., amplification of excitations at lower frequencies to obtain a sufficient signal-to-noise ratio (SNR) in elastic coupling assemblies)), or (5) a combination of some or all of the above (e.g., transmission loss compensation by transmittance filtering).

[0049] In some implementations, the controller 701 is configured to determine whether an applied excitation signal requires adjustment based on the following information: (1) non-feedback adjustment using an integrated “exciter calibration database,” (2) feedback from a connected data acquisition system (DAQ), and / or (3) feedback from a MIMO data processing system. In some implementations, the “exciter calibration database” used by the controller 701 to perform non-feedback adjustment includes information about the connected vibration exciters, along with knowledge of which vibration exciters are currently operating (for example, a predetermined exciter-specific equalization filter is applied to the excitation signal to linearize the exciter output each time an exciter operates). In some implementations, the DAQ itself may be configured to perform internal data quality checks to analyze the most recent individual SIMO / SISO experiments, with the results communicated to the controller 701 via an appropriate protocol. Finally, in some implementations, the controller 701 (or a separate MIMO data processing system) is configured to process and analyze the entire set of individual SIMO / SISO measurements and / or measurements reconstructed as one or more MIMO matrices. As described above, in some implementations, the system, as shown in Figures 4 to 6, is configured to address individual and overall data quality / consistency simultaneously.

[0050] Figures 13A to 13D show an example of a test system (e.g., the system in Figures 4 to 6) configured to adjust the applied force (X) (i.e., the actual vibration applied to the device / structure under test in response to the excitation signal) in response to the detected vibration response (Y). The test system in this example is configured to apply a signal quality test to evaluate the signal-to-noise ratio (SNR). The example in Figure 13A includes a separate MIMO data processing system 1301 configured to analyze the collected data and a control logic 1303 configured to adjust the excitation signal in response to feedback received by the control logic 1303 from the MIMO data processing system 1301. In some implementations, a single controller (e.g., controller 701) may be configured to provide the functionality of both the MIMO data processing system 1301 and the control logic 1303, as described in this example. In other implementations, the controller (e.g., controller 701) may be configured to provide the functionality of the control logic 1303, and the data acquisition systems 509 / 603 may be configured to provide the functionality of the MIMO data processing system 1301. Other combinations of logical components and functional distributions are also possible in other implementations.

[0051] As shown in Figure 13A (and as described in the other examples above), the SISO signal generator 501 is configured to generate an excitation signal in response to a control signal received from the control logic 1303, and in this example, it is configured to normalize the excitation signal output for each individual vibration exciter 109 (i.e., an excitation signal with an amplitude of ±1). An example of the normalized signal x(t) generated by the SISO signal generator 501 is shown in Figure 13B. The normalized excitation signal x(t) is then provided as input to the SISO power amplifier 503, which outputs a tuned excitation signal that is routed to the vibration exciters 109. The vibration exciters 109 apply a vibration excitation force x(t) to the apparatus / structure under test, and the actual vibration is measured by the corresponding load cell 111. An example of the actually applied vibration X measured by the load cell 111 is shown in the frequency domain representation (X(ω)) in Figure 13C. The applied force is transmitted through the device / structure 103 under test, and the actual vibrations at other locations on the device / structure under test are routed to the data acquisition system 509 / 603. The data input indicating the detected vibration y(t) is collected by or transmitted to the MIMO data processing system 1301. An example of the detected vibration Y measured by the response sensor 107 is shown in the frequency domain representation (i.e., response spectrum Y(ω)) in Figure 13D.

[0052] In the example shown in Figure 13A, the MIMO data processing system 1301 is configured to apply one or more signal quality tests to the acquired data, including at least one signal quality test designed to determine whether the acquired data exhibits a sufficient signal-to-noise ratio. The MIMO data processing system 1301 sends feedback to the control logic 1303 indicating the result of the signal quality test (i.e., that the SNR is sufficient), and based on the received feedback, the control logic 1303 determines whether the adjustment to the excitation signal is appropriate.

[0053] To demonstrate the adjustment mechanism in the example in Figure 13A in more detail, Figures 13B to 13D show examples of various signals both before and after the excitation signal is adjusted by the control logic. In Figure 13B, the upper graph shows the original excitation signal, and the lower graph shows the adjusted excitation signal. In Figure 13C, the upper graph shows the force spectrum X(ω) of the actual force applied to the device / structure under test (measured by load cell 111) in response to the original excitation signal, and the lower graph shows the force spectrum X(ω) of the actual force applied in response to the adjusted excitation signal. In Figure 13D, the upper graph shows the response spectrum Y(ω) based on the output of response sensor 107 when the original excitation signal is applied, and the lower graph shows the response spectrum based on the output of response sensor 107 when the adjusted excitation signal is applied.

[0054] The original excitation signal (shown in the upper graph of Figure 13B) is a random (broadband white noise) time signature x(t). The applied force in response to this original excitation signal (shown in the upper graph of Figure 13C) is characterized by a moderately broadband frequency spectrum X(ω) with a significant force drop in the higher frequency range. In this example, the excitation frequency range extends to a low frequency region of frequencies unrelated to this particular experiment (shown as “unimportant frequency range” in Figure 13C). However, this low-frequency excitation component may limit the ability of the vibration exciter 109 to provide high-energy output in a more relevant frequency range (e.g., the higher frequency range in the upper graph of Figure 13C where the signal begins to drop). In practice, the force drop to the illustrated high frequencies may be due to internal attenuation by simultaneously exciting all frequencies (e.g., using a random white noise excitation signal). Thus, the vibration exciter 109 is attempting to overcome large strokes at low frequencies while simultaneously superimposing small stroke motions at high frequencies. The applied vibration causes the device / structure under test 103 to vibrate linearly and time-invariantly (LTI) in response to the applied force, which is then detected by the response sensor 107.

[0055] In the upper graph of Figure 13D, the spectrum of the detected response vibration Y(ω) is plotted together with the spectrum of the sensor noise floor. In some implementations, the sensor noise floor may be measured under the same conditions when no excitation is applied to the device / structure 103 under test. As mentioned above, the "quality" of the detected vibration can be analyzed in various different ways. However, in this example, the upper graph of Figure 13D shows a signal-to-noise problem in the region where the detected vibration spectrum Y(ω) is close to the sensor noise floor. In some implementations, the data quality condition may be defined as a detected signal at least 10 dB higher than the sensor noise floor at this frequency. However, in the example of the upper graph of Figure 13D, the detected vibration Y(ω) suffers from an insufficient signal-to-noise distance due to the expected anti-resonance of the structure and, generally, at high frequencies due to relatively low force excitation (as a result of high internal damping of the vibration exciter).

[0056] In this example, the MIMO data processing system 1301 is configured to analyze detected vibrations to identify insufficient data quality (i.e., insufficient SNR) and send a feedback message to the control logic 1303. In response, the control logic 1303 initiates automatic adjustment of the applied vibrations to mitigate the detected signal quality problem. In some implementations, the control logic 1303 is configured to identify appropriate adjustments to the excitation signal based on detailed feedback regarding the frequency range where excitation is insufficient, along with additional metadata provided by the user regarding the target frequency range and / or time requirements for measurement.

[0057] In this particular example, the configuration of the control logic 1303 determines, based on feedback from the MIMO data processing system 1301, that the "type" of the excitation signal should be changed from a random broadband white noise excitation signal (shown in the upper graph of Figure 13B) to a logarithmic sweep signal (shown in the lower graph of Figure 13B). By doing so, the vibration exciter generates vibrations at a single frequency at a time, and thus prevents the vibration exciter from internally damping while simultaneously maximizing the force output. In this example, a logarithmic frequency sweep is used instead of a linear sweep to give the device / structure 103 under test sufficient time to respond to the applied vibration, especially when it is more difficult to excite lower frequency ranges.

[0058] In this example, the control logic 1303 also determines, based on feedback from the MIMO data processing system 1301, that additional adjustments to the excitation frequency range may be appropriate (for example, to prevent damage to the vibration exciter due to excessive stroke at low frequencies exceeding the frequency range of interest, and / or to minimize the duration of the measurement). In this example, this is achieved by applying a high-pass filter to the SISO signal generator 501 during the signal generation process. This high-pass filter prevents the vibration exciter from operating at low frequencies, and the applied force spectrum X(ω) after adjustment to the excitation signal is optimized in preference to the frequency range of interest, as shown in the lower graph of Figure 13C. It should also be noted that equivalent signal amplification is sufficient to achieve significantly higher exciter force output by operating the exciter at one frequency at a time. In some implementations, a similar filter can also be applied as a low-pass filter to block higher frequencies in order to avoid high shaker temperatures during continuous operation. Other adjustments to the force signal x(t) may include changes in signal amplitude. For example, the sinusoidal signature of the signal in Figure 13B can be amplified or attenuated at a specific frequency to "shape" the force characteristic X(ω) in Figure 13C. In some implementations, the signal generator is configured to apply these adjustments. This allows, for example, the application of higher forces at lower frequencies, which may be useful for structures coupled using rubber isolators, where high excitation energy is required to produce low-frequency response signals on the structure due to energy dissipation in the rubber isolators.

[0059] The vibration spectrum X(ω) applied in response to the tuned excitation signal results in better overall excitation of the device / structure under test, as shown by the graph below Figure 13D, which exhibits a significantly higher vibration response spectrum Y(ω) with increased separation between the detected signal and the sensor noise floor. Therefore, when the MIMO data processing system 1301 receives the updated detected signal and applies a similar signal quality test, the output of the signal quality test indicates that the signal quality problem (i.e., insufficient SNR) is sufficiently mitigated, and even the anti-resonance of the device / structure under test (i.e., the measured minimum amplitude level of the response signal) is clearly separated from the sensor noise floor. The higher quality response spectrum, along with the measured force spectrum of the applied vibration, can be fully utilized to determine a high-quality SRF between the corresponding excitation and response degrees of freedom (i.e., the corresponding vibration exciter 109 / response sensor 107 combination).

[0060] In the examples shown in Figures 13A to 13D, the excitation signal tuning strategy is fully automated and performed by the MIMO data processing system 1301 and the control logic 1303 (for example, both implemented in the controller 701 in some implementations) without direct user input. However, in some implementations, the control logic 1303 may be configured to output feedback to the user indicating quantified signal quality and to receive user feedback indicating excitation signal tuning. In some such implementations, the control logic 1303 may be configured to prioritize this direct user feedback over the automated tuning strategy.

[0061] Similar excitation signal tuning strategies may be implemented in several implementations based on feedback received while tuning the applied vibration, taking into account one or more data quality indicators based on, for example, (i) applied vibration (e.g., force) only, (ii) detected vibration (e.g., acceleration) only, or (iii) both applied vibration and detected vibration. In some implementations, the output of the SISO signal generator 501 or SISO power amplifier 503 is used as a basis for tuning the applied vibration downstream, using numerical data representing a desired signal output that has been normalized or tuned together with, for example, additional performance-related criteria (e.g., the frequency response function of the amplifier or the transfer function from "output vibration" to "input current" of the vibration exciter), to estimate and tune the expected applied vibration.

[0062] Therefore, the systems and methods described herein facilitate the breakdown of complex experimental MIMO vibration tests into multiple sequentially executed SIMO or SISO SRF experiments, following a fully automated process, as shown in the example in Figure 7. After the initial setup of the test system, which includes equipping the device / structure 103 and / or specially designed fixtures 101, the controller 701 can autonomously perform all experiments, including data quality checks, complex database decision-making, and data post-processing. For example, a MIMO SRF vibration test in one implementation configuration may include the following process control steps: Specifically, (1) system setup and instrumentation (one setup; special fixtures may be used to facilitate measurement), (2) routing of excitation hardware (vibration excitation source and associated load cell, and / or use of additional / alternative methods to determine the actual force excitation), (3) routing of response sensor hardware and / or use of additional / alternative methods to determine the actual response of the test structure to the applied force excitation, (4) parameterization of the data acquisition (DAQ) system by the current SIMO or SISO experimental sequence (e.g., sensor calibration, dynamic range, sampling frequency, sampling duration, filtering, trigger, etc.), (5) collection of all SIMO or SISO experimental sequence data, (6) post-processing of the current SIMO or SISO experimental sequence data, including (in some implementations) quality assurance methods and associated process flow control (e.g., repeated experiments with improved excitation strategies or data acquisition parameterization if the quality assurance methods show poor results), (7) post-processing (and storage) of successful SIMO or SISO SRF experimental data and initiation of subsequent SIMO or SISO experiments, (8) reconstructed / updated MIMO This may include post-processing and provision of SRF measurements (which may involve performing additional numerical / model-based / hybrid data manipulation / transformation).

[0063] Therefore, various implementations of the systems and methods described herein may offer the following advantages over other MIMO test approaches: (1) a single signal generator and power amplifier can be shared by all exciters; (2) the number of excitation DoF and response DoF is not limited by the number of DAQ channels; (3) any excitation signal (transient, continuous, etc.) can be used while ensuring an optimal phase reference and improved signal-to-noise ratio (SNR); (4) the measurement range can be adjusted for each excitation used using an automated calibration process; and (5) difficult measurements can be divided into multiple parts, allowing the exciters to cool down between measurements (the post-processing method for data fragmentation). (6) the measured measurements can be reconstructed, (7) difficult measurements can be performed using different excitation sources by control strategies (different data (e.g., different exciters in different frequency ranges) can be reconstructed / merged using data post-processing methods), (8) in-situ exciter output calibration can be performed and / or the number of required exciter output sensors (e.g., load cells) can be reduced using reciprocal calibration methods, (9) local nonlinearity can be detected using appropriate signal generation and / or post-processing methods, and (10) signal generation can be performed independently of the number of SRFs to be determined.

[0064] Other features and advantages of the present invention are described in the following claims.

Claims

1. A method for automatically evaluating the MIMO force response characteristics of a structure under test, The aforementioned method, The method involves connecting a plurality of exciter devices to the structure under test, wherein each of the plurality of exciter devices is connected to one of a first plurality of fixed positions on the structure under test, The method involves coupling a plurality of response sensors to the structure under test, wherein each of the plurality of response sensors is coupled to a different position among a second plurality of fixed positions on the structure under test. The exciter router is operated to iteratively couple an excitation signal input to each of the plurality of exciter devices, wherein coupling the excitation signal input to the exciter device causes the exciter device to apply an excitation force to the structure under test based on the excitation signal input. The process involves collecting sensor data from the plurality of response sensors while the excitation force is applied to the structure under test, and the collection of the sensor data is performed by: While the excitation force is applied to the structure under test by the first exciter device among the plurality of exciter devices, a first set of sensor data is collected from each of the plurality of response sensors. While the excitation force is repeatedly applied to the structure under test by each additional exciter among the plurality of exciter devices, a subsequent set of sensor data is collected from each of the plurality of response sensors. This includes, Based on the collected sensor data, the MIMO system response function for the structure under test is determined. Methods that include...

2. The method according to claim 1, wherein operating the exciter router further includes coupling the excitation signal input to a second exciter device among the plurality of exciter devices after a first set of sensor data has been collected from each of the plurality of response sensors, and collecting a subsequent set of sensor data includes collecting a second set of sensor data from each of the plurality of response sensors while the excitation force is applied to the structure under test by the second exciter device.

3. Operating the exciter router further includes transmitting an exciter router control signal from an electronic controller to the exciter router, which, in accordance with the exciter router control signal, operates its multiple switching devices to couple the excitation signal input to one of a plurality of outputs and to electronically isolate all other outputs from the excitation signal input. The aforementioned method, Operating a load cell router to iteratively couple multiple load cells to a data acquisition input channel, wherein the multiple load cells include different load cells corresponding to each of the multiple exciter devices, and operating the load cell router includes operating the load cell router to selectively couple the data acquisition input channel to the load cell corresponding to the exciter device to which the excitation signal input is currently coupled. Based on the signal received by the data acquisition input channel, the actual excitation force applied to the structure under test is determined, The method according to claim 1, further comprising:

4. The method according to claim 1, wherein the collection of the sensor data includes collecting the sensor data by a data acquisition system, the data acquisition system includes a plurality of signal input channels, and each of the plurality of signal input channels is coupled to one different output of the plurality of response sensors.

5. Collecting the aforementioned sensor data is The sensor router is operated to connect the signal input channel of the data acquisition system to the output of the first response sensor among the plurality of response sensors, wherein the sensor router is configured to selectively connect the plurality of response sensors to the signal input channel of the data acquisition system. The data acquisition system collects sensor data from the output of the first response sensor, The method according to claim 1, further comprising:

6. Collecting the aforementioned sensor data is The sensor router is operated to sequentially connect the signal input channels of the data acquisition system to each additional response sensor among the plurality of response sensors, The data acquisition system collects sensor data from the output of each additional response sensor among the plurality of response sensors, The method according to claim 5, further comprising:

7. The method according to claim 6, further comprising operating the exciter router to operate the sensor router to sequentially couple the signal input channels of the data acquisition system to each additional response sensor among the plurality of response sensors, and then coupling the excitation signal input to a second exciter device among the plurality of exciter devices.

8. The method according to claim 1, wherein the collection of the sensor data includes collecting the sensor data while operating the exciter device until a complete set of data is collected, which includes different data signals measured in accordance with each of a plurality of combinations of the exciter device that applies the excitation force and the response sensor that measures the response to the excitation force applied by the exciter device that applies the excitation force.

9. The method according to claim 1, wherein coupling the plurality of exciter devices to the structure under test includes selectively coupling the structure under test to a test fixture, and the exciter device among the plurality of exciter devices is pre-installed at a position on the test fixture.

10. The method according to claim 1, wherein determining the MIMO system response function for the structure under test includes loading data collected for each different combination of exciter sensors into a system response function (SRF) matrix.

11. A test system for the automated evaluation of MIMO force response characteristics of a structure under test, The aforementioned test system is Multiple exciter devices that can be coupled to the structure under test, Multiple response sensors that can be coupled to the structure under test, A one-input, one-output signal generator configured to generate an excitation signal, A one-input, multiple-output exciter router configured to selectively couple the excitation signal from the one-input, one-output signal generator to each of the multiple exciter devices, wherein coupling the excitation signal to the multiple exciter devices means causing the exciter devices to apply an excitation force to the structure under test based on the excitation signal, A data acquisition system configured to collect sensor data from each of the plurality of response sensors that show the detected response to the applied excitation force, It is an electronic controller, While the excitation signal is applied to the first exciter device among the plurality of exciter devices, the excitation signal is applied to the first exciter device until a first set of sensor data is collected by the data acquisition system from each of the plurality of response sensors. While the excitation signal is repeatedly applied to each of the multiple exciter devices, the excitation signal is continued to be applied to each additional exciter device of the multiple exciter devices until an additional set of sensor data is collected by the data acquisition system from each of the multiple response sensors. Thus, an electronic controller configured to operate the one-input, multiple-output exciter router, A testing system equipped with the following features.

12. The aforementioned single-input multi-output exciter router includes a plurality of switching devices configured to selectively couple an input channel to each of a plurality of output channels while electronically isolating all disconnected output channels. The aforementioned single-input, multi-output exciter router is, The exciter router receives an exciter router control signal from the aforementioned electronic controller. Based on the received exciter router control signal, the excitation signal received from the one-input one-output signal generator on the input channel of the one-input multiple-output exciter router is selectively coupled to one of the multiple output channels of the one-input multiple-output exciter router. The test system according to claim 11, configured as follows.

13. The test system according to claim 11, wherein the data acquisition system includes a plurality of sensor input channels, and each sensor input channel of the data acquisition system is coupled to one different output of the plurality of response sensors.

14. The system further includes a multi-input, single-output sensor router with multiple sensor input channels and a signal output channel. Each sensor input channel is coupled to one different output from the plurality of response sensors. The signal output channel is coupled to the signal input channel of the data acquisition system. The multi-input single-output sensor router is configured to selectively couple individual sensor input channels to the signal output channel while electronically isolating all disconnected sensor input channels. The test system according to claim 11, wherein the data acquisition system is configured to collect sensor data from each of the plurality of response sensors by receiving the sensor data from the signal output channels of the multi-input single-output sensor router while the multi-input single-output sensor router iteratively couples each sensor input channel to the signal output channel.

15. The test system according to claim 14, wherein the electronic controller is configured to operate the multi-input single-output sensor router until a complete set of data is collected, including different data signals measured in accordance with each of a plurality of combinations of response sensors that measure the response to the excitation force applied by different exciter devices that apply the excitation force.

16. The test system according to claim 11, further comprising a test fixture, wherein the structure under test is selectively connectable to the test fixture, and the plurality of exciter devices are positioned on the test fixture such that each exciter device connects to the structure under test when the structure under test is connected to the test fixture.

17. The test system according to claim 11, wherein the electronic controller is further configured to determine the system response function for the structure under test by loading sensor data collected for each of a plurality of different combinations of exciter sensors into a system response function (SRF) matrix.

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