System for magnetostrictive measurement of a physical quantity

Abstract

In a system for the magnetostrictive measurement of a physical quantity, wherein the system comprises a transformer (2), wherein the transformer (2) comprises a deformation body (21) which is designed such that it deforms under the influence of the physical quantity and thus generates a magnetostrictive effect, wherein the system comprises a primary-side circuit (1) and a secondary-side circuit (3), wherein the secondary-side circuit (3) comprises a reference branch and a first tap branch, wherein the first tap branch is suitable for obtaining a first tap voltage from a first secondary winding (20).1) to tap the transformer (2) and to generate a first tap signal (23) on the basis of this first tap voltage, wherein the secondary-side circuit (3) is suitable to relate the first tap signal (23) to a reference signal (24) in the reference branch and thus obtain a measurement signal (25) which is at least approximately proportional to the physical quantity, wherein the secondary-side circuit (3) comprises a plurality of processing components (6.1...6.5, 7...7.3, 8, 9.1...9.5, 10.1...10.5) which are suitable to carry out a successive processing of the first tap signal, the processing includes a bandwidth reduction (11) of the first tap signal (23).

Description

Technical area

[0001] The invention relates to a system for the magnetostrictive measurement of a physical quantity according to the preamble of claim 1. The invention further relates to a vehicle, a method, a computer program and a computer-readable medium according to the independent claims. State of the art

[0002] Force and torque sensors based on magnetostrictive measurement principles are known in principle. However, these sensors are not yet ready for automotive applications and are significantly too expensive to manufacture for this sector. General description of the invention

[0003] The object of the invention is to eliminate or at least reduce the disadvantages of the prior art.

[0004] The object is achieved by a system for the magnetostrictive measurement of a physical quantity, wherein the system comprises a transformer, wherein the transformer comprises a deformation body which is designed such that it deforms under the influence of the physical quantity and thus generates a magnetostrictive effect, wherein the system comprises a primary side circuit and a secondary side circuit, wherein the secondary side circuit comprises a reference branch and a first tap branch, wherein the first tap branch is suitable for tapping a first tap voltage from a first secondary winding of the transformer and for forming a first tap signal based on this first tap voltage, wherein the secondary side circuit is suitable for relating the first tap signal to a reference signal in the reference branch and thus obtaining a measurement signal which is at least approximately proportional to the physical quantity,wherein the secondary side circuit comprises a plurality of processing components which are suitable for performing a successive processing of the first tap signal, wherein the processing comprises a bandwidth reduction of the first tap signal.,

[0005] A physical quantity is understood to mean, in particular, a force or a torque. The transformer can alternatively be referred to as a magnetostrictive coupling element. The deformable body is typically a core of the transformer. A magnetostrictive effect is typically understood to mean a change in the magnetic properties of the transformer, in particular due to the deformation of the deformable body. The primary-side circuit is typically located on the primary side of the transformer, and the secondary-side circuit on the secondary side of the transformer. The tapped signal changes due to the successive processing by the processing components as it passes through the secondary-side circuit.In other words, as the tapped signal travels through the secondary-side circuit, it is subjected to continuous signal processing, which continuously and step-by-step changes the tapped signal. As part of this change, the bandwidth of the first tapped signal is also reduced. This bandwidth reduction makes it possible to make the hardware required for the secondary-side circuit relatively small compared to the hardware required in the prior art. This small size results in a cost reduction compared to prior-art systems, as well as space and weight savings.

[0006] In advantageous embodiments, the system comprises at least one further tapping branch, preferably several further tapping branches. In advantageous embodiments, at least some, preferably all, tapping branches of the secondary side circuit are at least substantially identical in construction. The term “substantially identical” is to be understood as meaning that identical components are used, which, however, may have certain manufacturing-related tolerances and / or which may differ with regard to largely insignificant features. In typical embodiments, each tapping branch taps a tap voltage from its own secondary winding of the transformer. Typically, the number of secondary windings of the transformer corresponds, for example, to the number of tapping branches in the system.Alternatively, it is also possible for one tap branch to tap multiple secondary windings simultaneously, or for multiple tap branches to each tap multiple secondary windings. In advantageous embodiments, the system is capable of implementing the bandwidth reduction in each tap branch.

[0007] In typical embodiments, each tapping branch comprises a bandpass filter and / or a peak-value rectifier and / or an instrumentation amplifier, wherein each tapping branch preferably has its own bandpass filter and / or its own peak-value rectifier and / or its own instrumentation amplifier. In particular, a combination of these components, preferably in a configuration where all tapping branches are identical, has the advantage that good symmetry and offset-free operation of the individual channels relative to one another can be achieved. The different components can in principle be arranged in different orders in the tapping branches, wherein different arrangements each have different advantages and disadvantages, as will be explained below in the context of specific exemplary embodiments. In typical embodiments, however, the components in all tapping branches are arranged in the same order.

[0008] In advantageous embodiments, each tapping branch comprises a differential amplifier, wherein preferably several tapping branches, advantageously all tapping branches, share a common differential amplifier.

[0009] In advantageous embodiments, each tap branch comprises a phase measuring circuit and / or an amplitude and phase measuring circuit, wherein preferably several tap branches, advantageously all tap branches, share a common phase measuring circuit and / or a common amplitude and phase circuit.

[0010] In typical embodiments, the reference branch comprises an instrumentation amplifier and / or a differential amplifier and / or a bandpass filter and / or a peak value rectifier and / or a phase measuring circuit and / or an amplitude and phase measuring circuit. In advantageous embodiments, the secondary side circuit is suitable for performing a bandwidth reduction on the reference signal. In typical embodiments, the reference branch is at least partially structurally identical to at least one tapping branch. In typical embodiments, the reference branch is structurally identical to all tapping branches. In typical embodiments, the reference branch shares a differential amplifier and / or a phase measuring circuit and / or an amplitude and phase measuring circuit with at least one tapping branch, preferably with all tapping branches.

[0011] In typical embodiments, the first tap branch is suitable for tapping a further tap voltage from a further secondary winding of the transformer and also for forming the first tap signal on the basis of this further tap voltage.

[0012] In typical embodiments, the secondary side circuit comprises a calculation component capable of forming the measurement signal based on all tapped signals and the reference signal. In typical embodiments, the system is configured such that all tapped signals are fed into the calculation component, and the reference signal is also fed into the calculation component.

[0013] In typical embodiments, the primary-side circuit comprises a signal generation component and a driver component. The signal generation component is typically capable of generating a pulse-width modulated signal and feeding it to the driver component.

[0014] In typical embodiments, the driver component comprises a low-pass filter and / or a band-pass filter and / or an amplifier component and / or a matching network, wherein the matching network is preferably arranged on the output side of the amplifier component. In advantageous output forms, the

[0015] In advantageous embodiments, at least some of the aforementioned filters, amplifiers, circuits, components, rectifiers or other assemblies of the system are at least partially implemented by means of computer program code.

[0016] The object is further achieved by a vehicle comprising a system according to the invention.

[0017] The object is further achieved by a method for the magnetostrictive measurement of a physical quantity, wherein, within the scope of the method, a deformation body of a transformer is deformed under the influence of the physical quantity and thus generates a magnetostrictive effect, wherein, within the scope of the method, a first tap voltage is tapped from a first secondary winding of the transformer and a first tap signal is formed on the basis of this first tap voltage, wherein, within the scope of the method, the first tap signal is related to a reference signal in order to thus obtain a measurement signal which is at least approximately proportional to the physical quantity, wherein, within the scope of the method, successive processing of the first tap signal is carried out, and wherein the processing comprises a bandwidth reduction of the first tap signal.In typical embodiments, the method is implemented using a system according to at least one of the previously described embodiments. In advantageous embodiments, the bandwidth reduction is performed in a system with a plurality of tap branches in each tap branch.

[0018] The object is further achieved by a computer program comprising steps which, when executed on a computer, cause the computer to carry out a method according to at least one of the aforementioned embodiments, at least in part.

[0019] In one embodiment of the invention, a computer-readable medium comprises computer program code for performing at least one step, preferably a plurality of steps, of one of the aforementioned methods. The term "computer-readable medium" refers in particular, but not exclusively, to hard drives and / or servers and / or memory sticks and / or flash memories and / or DVDs and / or Blu-rays and / or CDs. In addition, the term "computer-readable medium" also refers to a data stream, such as that generated when a computer program product is downloaded from the Internet. Short description of the drawings

[0020] In the following, the invention is briefly explained with reference to drawings, in which: Fig. 1: a system according to the invention in a first embodiment, Fig. 2: a system according to the invention in a second embodiment, Fig. 3: a system according to the invention in a third embodiment, Fig. 4: a system according to the invention in a fourth embodiment, Fig. 5: a system according to the invention in a fifth embodiment, Fig. 6: a system according to the invention in a sixth embodiment, Fig. 7: a system according to the invention in a seventh embodiment, Fig. 8: a system according to the invention in an eighth embodiment, and Fig. 9: a system according to the invention in a ninth embodiment. Description of preferred embodiments

[0021] Fig. Figure 1 shows a system according to the invention in a first embodiment. In particular, Fig. 1 shows a system with a primary side circuit 1, a transformer 2, and a secondary side circuit 3. The primary side circuit 1 includes a signal generating component 4 and a driver component 5. The signal generating component 4 typically generates a pulse-width modulated signal, which it sends to the driver component 5. In Fig. In Figure 1 and all subsequent figures, signal transmissions between the different components are represented by arrows. The transformer 2 comprises a core 21, a primary winding 19, and four secondary windings 20.1, 20.2, 20.3, 20.4. The secondary windings 20.2, 20.3, 20.4 are shown dashed and hatched, whereas the secondary winding 20.1 is shown in black. This is intended to express that the secondary windings 20.2, 20.3, 20.4 are not absolutely necessary, but rather are optional. The primary-side circuit 1 further comprises a measuring shunt 22, which advantageously enables a voltage across the primary winding 19 to be measured. The following figures also each comprise a transformer 2 with a primary winding 19 and a plurality of secondary windings and a core. These figures also show a measuring shunt 22.For the sake of clarity, however, these components are not provided with their own reference numerals in the following figures. The secondary side circuit 3 comprises a first tap branch, which includes an instrumentation amplifier 6.1, a differential amplifier 7, a bandpass filter 9.1, and a peak-value rectifier 10.1. These components 6.1, 7, 9.1, 10.1 are arranged in this order in the first tap branch, viewed from the first secondary winding 20.1. The instrumentation amplifier 6.1 thus taps a tap voltage from the first secondary winding 20.1 and, based on this first tap voltage, forms a first tap signal 23, which successively passes through the first tap branch from the instrumentation amplifier 6.1 via the differential amplifier 7 and the bandpass filter 9.1 and the peak-value rectifier 10.1, where it is processed step by step.The secondary side circuit 3 further comprises a reference branch which includes an instrumentation amplifier 6.5, the differential amplifier 7, a bandpass filter 9.5 and a peak value rectifier 10.5. The reference signal 24 is tapped on the primary side of the transformer 2 and processed in the same way as the first tapped signal 23. The first tapped signal 23 and the reference signal 24 are also shown in the following figures, but for the sake of clarity they are no longer provided with reference symbols. The first tapped signal 23 and the reference signal 24 are fed to the calculation component 8, in which a measurement signal 25 is formed based on the first tapped signal 23 and the reference signal 24. This measurement signal 25 is a raw data signal which is typically, to a first approximation, proportional to a physical quantity acting on the core 21 of the transformer 2. This acting quantity is shown in . Fig. 1 is not explicitly shown; however, when it acts on the core 21 and deforms it, a magnetostrictive effect occurs, which is reflected in a more or less large tap voltage at the first secondary winding 20.1 (and at the optional secondary windings 20.1, 20.3, 20.4). Fig. The system shown in Figure 1 further comprises three additional optional tap branches, the components of which are shown in Fig. 1 are shown in dashed lines to indicate that these branches are optional. This is the second tap branch, which comprises (in this order from the second secondary winding 20.2) an instrumentation amplifier 6.2, the differential amplifier 7, a bandpass filter 9.2, and a peak-value rectifier 10.2. The third tap branch similarly comprises an instrumentation amplifier 6.3, the differential amplifier 7, a bandpass filter 9.3, and a peak-value rectifier 10.3. The fourth tap branch similarly comprises an instrumentation amplifier 6.4, the differential amplifier 7, a bandpass filter 9.4, and a peak-value rectifier 10.4. Fig. 1, it can be seen that the four tap branches and the reference branch share the differential amplifier 7. The optional tap branches also each provide the calculation component 8 with a tap signal, which the calculation component 8 takes into account when calculating the measurement signal 25. Furthermore, Fig. Figure 1 shows that a bandwidth reduction 11 of the tap signals and the reference signal is performed in the peak value rectifiers 10.1, 10.2, 10.3, 10.4, and 10.5. Thus, the calculation component contains 8 tap signals and a reference signal with reduced bandwidth, which minimizes the hardware complexity in the calculation component.

[0022] The following can be said regarding Fig. 1: On the primary side of transformer 2, the test signal is generated (= active excitation of the magnetostrictive coupling element in the center of the image, specifically core 22). On the secondary side of transformer 2, the output signals of the magnetostrictive inductive coupling element are amplified while maintaining sensitivity and offset, correlated by subtraction, and bandpass filtered. Bandwidth reduction is also performed. This ideally occurs early in the signal flow, thus avoiding the expense of bandwidth bias, which would have a detrimental cost effect, particularly on the part of further digital processing.

[0023] Fig. Figure 2 shows a second embodiment of a system according to the invention. Fig. The system shown in Figure 2 is similar to the one shown in Fig. 1. The primary side circuit 1 and the transformer 2 correspond exactly to the system shown in Fig. 1. The secondary side circuit 3 of the embodiment shown in Fig. The embodiment shown in Figure 2 is similar to the one shown in Fig. 1. Everything related to Fig. 1 Reference is made to what has been said. In contrast to Fig. 1, the differential amplifier 7 is in Fig. 2, however, is not arranged between the instrumentation amplifiers 6.1, ..., 6.5 and the bandpass filters 9.1, ..., 9.5, but on the output side at the peak value rectifiers 10.1, ..., 10.5 and thus directly at the input of the calculation component 8. Thus, the bandwidth reduction 11 is also present in the differential amplifier 7.

[0024] The following can be said regarding Fig. 2 say: In contrast to the Fig. In the embodiment shown in Figure 1, the differential amplifier 7 is mounted in the bandwidth-reduced part of the signal path. This has the disadvantage that offset and sensitivity influences from bandpass filters and peak-value rectifiers are also included in the difference calculation. This must be weighed against the advantages of a further reduction in hardware complexity due to the bandwidth reduction. Furthermore, in this variant, phase differences are no longer included in the difference calculation, which is advantageous if they reduce the difference signal.

[0025] Fig. Figure 3 shows a third embodiment of a system according to the invention. This system again comprises a primary side circuit 1 as already shown in the previous figures, a transformer 2 and a secondary side circuit 3. The Fig. The embodiment shown in Figure 3 comprises a first tap branch, which comprises a differential amplifier 7.1, a bandpass filter 9.1, and a peak-value rectifier 10.1, which are arranged in this order in the first tap branch, as seen from the transformer 2. The differential amplifier 7.1 respectively taps an output voltage from a first secondary winding and a second secondary winding of the transformer 2. For the sake of clarity, the secondary windings, as already mentioned, are not provided with their own reference numerals. Furthermore, the system in Fig. 3, a second tap branch, which is optional (as indicated by the dashed lines in the second tap branch), and which comprises a differential amplifier 7.2, a bandpass filter 9.2, and a peak-value rectifier 10.2. These components are arranged in exactly this order in the second tap branch, as seen from the transformer 2. Furthermore, the embodiment in Fig. 3, a reference branch, which comprises an instrumentation amplifier 6.5, a bandpass filter 9.5, and a peak-value rectifier 10.3. The two tap branches and the reference branch feed their respective signals into the calculation component 8, which generates the measurement signal 25 based on these tap signals and this reference signal. The bandwidth reduction 11 is in Fig. 3 is also present and starts at the level of bandpasses 9.1, 9.2, 9.5.

[0026] Fig. Figure 4 shows a fourth embodiment of a system according to the invention. Fig. The system shown in Figure 4 comprises a primary side circuit 1, a transformer 2, and a secondary side circuit 3. The primary side circuit 1 and the transformer 2 essentially correspond to the embodiments shown in the previous figures. Accordingly, reference is made to the explanations relating to these figures. The secondary side circuit 3 in turn comprises a reference branch, which corresponds to the Fig. 3 shown reference branch. The Fig. The system shown in Figure 4 further comprises three tapping branches. The first tapping branch comprises a differential amplifier 7.1, a bandpass filter 9.1, and a peak-value rectifier 10.1, arranged in this order from the transformer 2. The optional second tapping branch comprises a differential amplifier 7.2, a bandpass filter 9.2, and a peak-value rectifier 10.2, arranged in this order from the transformer 2. The optional third tapping branch comprises a differential amplifier 7.3, a bandpass filter 9.3, and a peak-value rectifier 10.3, arranged in this order from the transformer 2. The differential amplifiers 7.1, 7.2, and 7.3 are each connected to several secondary windings of the transformer 2. The three tapping branches and the reference branch in turn feed their signals into the calculation component 8, which generates the measurement signal 25 based on these signals. Also in Fig. 4, as in the previous figures, the bandwidth reduction 11 is shown.

[0027] The following can be said regarding Fig. 3 and Fig. 4: In these embodiments, the differential amplifiers are arranged in the signal flow immediately behind the secondary windings of the transformer (or in other words, the magnetostrictive coupling element). The advantage of eliminating offset and sensitivity contributions from other components must be weighed against the potential disadvantage of an ohmic load on the secondary coils, in which a (usually small) current can flow, depending on the design of the differential amplifier.

[0028] Fig. Figure 5 shows a fifth embodiment of a system according to the invention. The embodiment Fig. 5 corresponds to the embodiment in Fig. 1 with the difference that a phase measuring circuit 13 is used in the system instead of the differential amplifier 7. Otherwise, the embodiment in Fig. 5 identical to the embodiment in Fig. 1. Typically, the secondary side circuit 2 evaluates Fig. 5 predominantly a phase difference of the tap signals relative to the reference signal.

[0029] Fig. Figure 6 shows a sixth embodiment of a system according to the invention. The embodiment in Fig. 6 corresponds to the embodiment in Fig. 5 with the only difference that instead of the phase measuring circuit 13, an amplitude and phase measuring circuit 14 is used in the system. For further information, please refer to the explanations of Fig. 1 and Fig. 5. Typically, in the secondary side circuit 2 in Fig. 6 Amplitude differences and / or ratios of the tapped signals to each other, as well as phase differences to the reference signal are evaluated as a force or torque signal.

[0030] In a variant of the Fig. In the embodiment shown in Figure 5, the amplitude and phase determination is performed using a lock-in amplifier or QI / quadrature demodulator. In this variant, bandpass filtering and peak-value rectification are omitted, as these are already included in a lock-in amplifier or QI / quadrature demodulator. The increased component complexity is not significant, especially when implemented using integrated electronics, and is typically compensated for by advantages regarding offset and sensitivity stability, as well as the ability to consider both signal components (redundancy and additional correction options).

[0031] To achieve a functional safety level according to ISO 26262 (or similar), parts of the secondary side circuit 3 can be redundant and / or supplemented by modules that monitor the function of other modules. Furthermore, intermediate signals in the system branches can be used to monitor the proper functioning of the secondary side circuit 3 and / or the entire system by checking their signal content.

[0032] Fig. Figure 7 shows a seventh embodiment of a system according to the invention. Fig. The embodiment shown in Figure 7 corresponds to the embodiment in Fig. 1, and to the statements relating to Fig. 1 is therefore incorporated herein by reference. In addition to the provisions Fig. The system comprises the components shown in Figure 1 Fig. 7, however, additionally includes a calibration component 15, which is arranged on the output side of the calculation component 8. This calibration component 15 performs a calibration of the measurement signal 25, also using a plurality of calibration influencing variables 16, which may include, for example, a temperature, a disturbing magnetic field, aging, and / or other influencing variables.

[0033] The following can be said regarding Fig. 7: In this exemplary embodiment, for example, a raw torque signal, in particular a raw torque signal based in particular on the tapped signals, is converted into a precise force or torque signal 25. The conversion is determined by comparison with a physical reference (a standard). In an advantageous embodiment, polynomials are used for this purpose, and the coefficients of optimal accuracy are determined by a calibration measurement. In addition to the direct load calibration, further calibration influencing variables 16 (e.g., temperature and interfering magnetic fields, aging) can be calibrated to the force or torque result or taken into account as correction variables.

[0034] Part of the practical implementation of the active force or torque sensor can be magnetic field monitoring. This is useful because magnetic fields that are not causally related to the sensor principle can change the operating point of the sensor and thus influence the sensor behavior. For this purpose, a suitable magnetic field sensor can be integrated directly into a system according to the invention, or a connection option for such a sensor can be integrated into the system. The magnetic field measurement variable can, on the one hand, be considered as a monitoring variable, which ensures that the interference fields remain within an acceptable tolerance corridor. On the other hand, it can also be used to correct the force or torque signal in the sense of the text for the below-described Fig. 9 can be used. The system can contain a corresponding unit for this correction. Due to the fact that magnetic fields are vector fields, the system can detect and consider multiple components of the field in typical embodiments. In one variant of the invention, the coils and their inductances are used to determine the magnetic sensor operating point. For this purpose, the driver component 5, for example, can contain electronic devices for measuring the mutual induction (= voltage measurement) of the primary winding and a possibility of offsetting this against the current flow to an inductance.

[0035] By using multiple secondary windings and corresponding tap branches, it is possible to detect, process, and computationally compensate for certain disturbances in the measurement of the physical quantity. This applies in particular to changes in distance, tilting of the transformer's winding system relative to the deformation body, temperature changes between the winding system and the deformation body, spatial temperature gradients, and / or magnetic interference fields. Mathematically, the use of more windings and correspondingly more tap branches achieves overdetermination in the sense of linear algebra. The use of more windings and / or tap branches is particularly interesting when these result in only minimal additional costs, as is the case with the implementation of the electronics in an integrated circuit, or when these costs are offset by the additional benefits.The disturbances, as mentioned above, can also be measurement and output signals of the system.

[0036] In a special embodiment, for example, only one, two, three, or significantly more, e.g., seven, eight, or ten secondary windings and tap branches are present in the secondary side circuit. Especially for force measurements, measuring only a single force and thus a single magnetization direction may be sufficient, so that in principle, a single secondary winding and correspondingly one tap branch are sufficient. However, this also eliminates the possibility of compensating for disturbances, which is generally possible for measuring bridges.

[0037] Fig. Figure 8 shows an eighth embodiment of a system according to the invention. The embodiment in Fig. 8 corresponds to the Fig. 1 shown embodiment, and to the explanations relating to Fig. 1 is therefore incorporated herein by reference. In addition to the provisions already Fig. 1 components shown, the embodiment in Fig. 8, however, an adaptation network 12, 12.1, ..., 12.4. The adaptation network is in Fig. 8, the matching network is thus arranged around the transformer 2. Alternatively, it is also possible for the matching network to be arranged, for example, only on the primary side of the transformer 2, namely in the primary-side circuit 1, preferably between the driver component 5 and the transformer 2, in particular a coil component of the transformer 2.

[0038] As the area and number of turns of the primary winding of transformer 2 increase, as does the frequency and "loading" with ferromagnetic / magnetostrictive material, it typically becomes increasingly difficult (due to the law of induction) for driver component 5 to drive the necessary current through this primary winding (also referred to as the primary coil). This is especially true if this current is supplied from a low-voltage source (5 V or 12 V vehicle voltage) and the mutual induction of the primary coil approaches or even exceeds this supply voltage. At this point, the voltage is no longer sufficient to drive the desired alternating current. In typical embodiments, the system therefore comprises a matching network, which is advantageously arranged between driver component 5 and the primary coil. This matching network typically operates the primary coil in series or parallel resonance, or a mixture of the two.This matching network typically exploits the inherent increase in voltage and / or current in the resonant circuit to raise these values ​​above the level of the power supply. In typical embodiments, the matching network comprises one or more damping elements, which inherently reduce the quality of the resonance but increase the width of the resonance, for example to reduce the frequency sensitivity of the system, in particular of the primary side circuit and / or the secondary side circuit. In some embodiments, the matching network can also be part of the driver component 5. In typical embodiments, the matching network comprises feedback connections for the driver component 5 in order to adapt the frequency of the system, in particular of the primary side circuit and / or the secondary side circuit, to the position of the resonance or to make this detectable.

[0039] Fig. Figure 9 shows a system according to the invention in a ninth embodiment. The system in Fig. 9 corresponds to the Fig. 7 and includes in addition to the Fig. 7, a communication component 17, which is connected downstream of the calibration component 15, and a data exchange module 18. The data exchange module 18 can, for example, be a BUS system, which enables the various components of the Fig. 9 shown system enables them to communicate with each other.

[0040] The following should be noted in this regard: in principle, it is possible and in accordance with the invention to transmit the tapped signal(s) or, more generally, signals within the system in analog form (for example, as a voltage, current, PWM signal, or frequency signal). However, particularly in modern vehicles, it is typically advantageous to implement signal transmission and / or communication within the system via a digital connection. Solutions such as CAN bus, SENT, LIN, FlexRay, or the like can be used for this purpose. In typical embodiments, the system therefore comprises a digital communication component (can also be referred to as a communication module), wherein the system is suitable for communicating at least one torque signal via the digital communication component.Status and monitoring signals, such as signal qualifiers, CRC, life counters or the like for torque and other measured variables, as well as communication for calibration, compensation, correction, error memory and similar functions can also be transmitted and / or carried out via this communication component in typical embodiments.

[0041] In typical embodiments, the primary-side circuit and the secondary-side circuit are discretely constructed from individual electronic components. In advantageous embodiments, however, the individual components, modules, or the like are housed in a more or less highly integrated manner in several or a single electronic circuit (for example, in one or more integrated circuits). This circuit(s) can be implemented in analog or digital form, or as a hybrid.

[0042] In typical embodiments, the system comprises integrated electronic circuits combined with external, possibly less tightly integrated, components, which allow modular adaptation to different coils, frequencies, and the like. This makes it possible to adapt a single, highly integrated, and inexpensively mass-produced electronic system for the system to a wide range of applications and technical design variants.

[0043] In a further embodiment not explicitly shown, a system according to the invention comprises a plurality of one of the Fig. 1 to 9, but without the calculation component 8. The majority of these systems then feed into a common calculation component 8. Such an embodiment is advantageous, for example, in cases where a rotating deformation body is used.

[0044] The following should be noted in this regard: In certain cases, e.g. in rotating applications in which the deformation body rotates or oscillates relative to the windings of the transformer, the homogeneity of the deformation body with regard to its magnetostrictive properties plays an important role. This cannot always be easily achieved. In typical embodiments, the system is designed such that the tapped signal or signals can be measured at several points. In typical embodiments, the system is suitable (e.g. by averaging or control engineering approaches or observers) for calculating the tapped voltage and / or measured tapped signals tapped at several points. In typical embodiments, the system therefore comprises a multiplication of the components required for measuring several measuring points and their calculation.The corresponding components can be constructed discretely or integrated in a module or integrated circuit.

[0045] The choice of the system's operating frequency, and in particular the transformer acting as the sensor and the signal shape, directly influences how deeply different frequency components of the magnetic flux density penetrate into the ferromagnetic and conductive material of the deformation body. Eddy currents in the deformation body have a shielding effect with increasing frequency and reduce the penetration depth. In advantageous embodiments, the system is suitable for selectively exciting different frequencies (simultaneously or successively) and / or performing frequency-selective evaluation. Frequency-selective evaluation can be performed using electronic filtering or a suitable demodulation or analysis technique (analog or digital). For the latter, particularly noteworthy techniques include QI demodulation, lock-in amplification (phase-locked loop, phase-sensitive rectification, SUPERHET amplification), and Fourier transformation.

[0046] In typical embodiments, the system is capable of providing a (typically relatively small) bypass current in the primary and / or secondary windings. On the primary side of the system, it influences the (magnetic) operating point of the system, and in particular of the transformer. On the secondary side, it can contribute to stabilizing the amplifiers, particularly the instrumentation or input amplifiers, for example, by avoiding the zero crossing of the amplifiers.

[0047] The flowing coil current (particularly in the primary winding), its frequency, and signal shape directly influence the voltage induced in the secondary coils and the voltage differences between the secondary coils. In typical embodiments, at least some of these variables (i.e., coil current and / or coil current frequency and / or coil current signal shape) are predetermined in the system and method, typically with a tolerance of, for example, 1%, 2%, 5%, or 7%. In typical embodiments, the coil current frequency is stabilized, for example, by means of a quartz component. In typical embodiments, the signal shape is stabilized, for example, by filtering. In typical embodiments, the amplitude of the coil current is stabilized, for example, by control.In typical embodiments, the system is capable of measuring these variables (i.e., coil current and / or coil current frequency and / or coil current waveform) and taking them into account in a suitable manner when determining the measurement signal. A "suitable manner" is one in which the accuracy of the measurement signal is increased to the desired level. For this purpose, (mathematical) models of the sensor principle, as well as measurement / calibration data, can be used, for example.

[0048] In typical embodiments, the system comprises one or more chopper amplifiers, with multiple chopper amplifiers advantageously arranged on and / or around the secondary coils. Such use of chopper amplifiers has the advantage of reducing offset and sensitivity drift of some system components. This design principle / amplifier type can mitigate relevant error influences, particularly for the input stages or instrumentation amplifiers of the secondary coils. To explain: Chopper amplifiers switch electronically and automatically, usually synchronously with the signal, between the signal to be amplified and a test / reference signal, and use this information to compensate for gain and offset. This principle is also applicable to differential amplifiers.In typical embodiments, one or more chopper amplifiers are therefore arranged on the differential amplifier and / or around the differential amplifier(s).

[0049] The present invention thus relates to an electronic arrangement—or in other words, a basic circuit—which enables the signal generation, detection, and evaluation of a force or torque sensor (in particular a transformer core) according to the so-called active magnetostrictive principle to produce a force or torque signal. The active magnetostrictive principle is characterized in that the magnetic field for measuring the magnetostrictive effect is generated by the system itself using a current-carrying coil. The electronic arrangement according to the invention is typically suitable for implementation using discrete electronics, integrated circuit elements, or in several or a single integrated electronic circuit element (ASIC or CSIC).Implementation as a programmatic sequence, for example, in the form of a computer program, on an FPGA or microcontroller is also possible in specific embodiments of the invention. In contrast, the list (discrete electronics, integrated circuit elements, ASIC or CSIC) represents a "natural" sequence, reducing unit costs as the number of units increases.

[0050] In typical embodiments of the invention, a differential transformer is used to measure force and torque using the magnetostrictive principle: The measurement object, a deformable body, for example, the core of a transformer, is part of the magnetic circuit and, due to external loads (force and / or torque), develops direction-dependent mechanical stresses. These, in combination with the inverse magnetostrictive effect (Villari effect), produce direction-dependent magnetic properties, the effect or differential effect of which is recorded in two or more orientations. The differential transformer mentioned above, typically with two or more secondary windings, generates a differential signal ("differential, inductive measuring bridge") between these secondary windings. This signal, with an appropriate design of the deformable body, is proportional to the acting force or torque to a first approximation. This difference(s) can be measured with high sensitivity using a suitable circuit.A suitable circuit is characterized by two main components in front of (“primary”) and behind (“secondary”) the transformer.

[0051] The primary side circuit, which can also be referred to as the driver circuit, drives a current of suitable amplitude, frequency and signal shape through the primary winding of the transformer. Typically, this subcircuit comprises signal generation and signal amplification. In an advantageous embodiment, the signal is generated digitally as a square wave, for example as the switching output of a digital circuit (e.g. microprocessor), is converted into a sine wave signal by a low-pass or band-pass filter (the aim: current with as few harmonics as possible), and amplified in a driver (also called the driver component) to the amplitude required to operate the coil and sensor. In a further advantageous embodiment, a matching network is located between the driver circuit (also called the driver stage) and the primary coil (also called the primary winding of the transformer).This makes it easier to drive the coil with the necessary current against its induced voltage, even with a limited supply voltage. It also reduces power dissipation in the driver stage, thus reducing its cost and size.

[0052] The following can be said about the secondary side circuit: The induced output voltages of the secondary coils (also referred to as secondary windings of the transformer) should advantageously be amplified with as little feedback as possible for them and symmetrically (with regard to offset and sensitivity). In an advantageous embodiment, the signals are then individually bandpass filtered and their amplitude determined, for example, using a low-bandwidth peak rectifier. From these signals, a raw signal for force or torque is generated, either by an analog adding / subtracting circuit or by digitization and subsequent digital processing. The symmetry and offset-free nature of the individual channels (also referred to as tap branches and reference signals) relative to one another is advantageous for the successful functioning of the circuit in terms of the desired measurement accuracy.

[0053] The invention is not limited to the described embodiments. The scope of protection is defined by the patent claims. Reference symbol 1 primary side circuit 2 transformer 3 Secondary side circuit 4 Signal generation component 5 Driver component 6.1...6.5 Instrument amplifiers 7, 7.1, 7.2, 7.3 differential amplifiers 8 Settlement component 9.1...9.5 Bandpass filters 10.1...10.5 Peak value rectifier 11 Bandwidth reduction 12, 12.1...12.4 Adaptation network 13 phase measuring circuit 14 Amplitude and phase measuring circuit 15 Calibration component 16 calibration influencing factors 17 Communication component 18 Data exchange module (e.g. BUS system) 19 Primary winding 20.1...20.4 Secondary winding 21 core 22 measuring shunt 23 first tap signal 24 Reference signal 25 measurement signal

Claims

[1] System for the magnetostrictive measurement of a physical quantity, - wherein the system comprises a transformer (2), wherein the transformer (2) comprises a deformation body (21) which is designed such that it deforms under the influence of the physical quantity and thus generates a magnetostrictive effect, - wherein the system comprises a primary side circuit (1) and a secondary side circuit (3), - wherein the secondary side circuit (3) comprises a reference branch and a first tap branch, - wherein the first tap branch is suitable for tapping a first tap voltage from a first secondary winding (20.1) of the transformer (2) and for forming a first tap signal (23) on the basis of this first tap voltage, - wherein the secondary side circuit (3) is suitable for relating the first tap signal (23) to a reference signal (24) in the reference branch and thus obtaining a measurement signal (25) which is at least approximately proportional to the physical quantity, - wherein the secondary side circuit (3) comprises a plurality of processing components (6.1...6.5, 7...7.3, 8, 9.1...9.5, 10.1...10.5) which are suitable for carrying out a successive processing of the first tap signal, characterized by that the processing comprises a bandwidth reduction (11) of the first tap signal (23). [2] System according to claim 1, characterized by that the system comprises at least one further tapping branch, preferably several further tapping branches, wherein at least some, preferably all tapping branches of the secondary side circuit (3) are at least substantially identical in construction. [3] System according to one of the preceding claims, characterized bythat each tapping branch comprises a bandpass filter (9.1...9.4) and / or a peak value rectifier (10.1...10.4) and / or an instrumentation amplifier (6.1...6.4), wherein preferably each tapping branch has its own bandpass filter (9.1...9.4) and / or its own peak value rectifier (10.1...10.4) and / or its own instrumentation amplifier (6.1...6.4). [4] System according to one of the preceding claims, characterized by that each tapping branch comprises a differential amplifier (7, 7.1, 7.2, 7.3), wherein preferably several tapping branches, advantageously all tapping branches, share a common differential amplifier (7). [5] System according to one of the preceding claims, characterized bythat each tap branch comprises a phase measuring circuit (13) and / or an amplitude and phase measuring circuit (14), wherein preferably several tap branches, advantageously all tap branches, share a common phase measuring circuit (13) and / or a common amplitude and phase measuring circuit (14). [6] System according to one of the preceding claims, characterized by , that - the reference branch comprises an instrumentation amplifier (6.5) and / or a differential amplifier (7) and / or a bandpass filter (9.5) and / or a peak value rectifier (10.5) and / or a phase measuring circuit (13) and / or an amplitude and phase measuring circuit (14), and / or - the secondary side circuit (3) is suitable for performing a bandwidth reduction (11) on the reference signal (24), and / or - the reference branch is at least partially identical in construction to at least one tap branch; and / or - the reference branch shares a differential amplifier (7) and / or a phase measuring circuit (13) and / or an amplitude and phase measuring circuit (14) with at least one tap branch, preferably all tap branches. [7] System according to one of the preceding claims, characterized by that the first tapping branch is suitable for tapping a further tapping voltage from a further secondary winding (20.2, 20.3, 20.4) of the transformer (2) and also for forming the first tapping signal (23) on the basis of this further tapping voltage. [8] System according to one of the preceding claims, characterized by that the secondary side circuit (2) comprises a calculation component (8) which is suitable for forming the measurement signal (25) on the basis of all tap signals (23) and the reference signal (24). [9] System according to one of the preceding claims, characterized bythat the primary side circuit (1) comprises a signal generating component (4) and a driver component (5). [10] System according to claim 9, characterized by that the driver component (5) comprises a low-pass filter and / or a band-pass filter and / or an amplifier component and / or a matching network, wherein the matching network is preferably arranged on the output side of the amplifier component. [11] A vehicle comprising a system according to any one of the preceding claims. [12] Method for the magnetostrictive measurement of a physical quantity, - wherein, within the scope of the method, a deformation body (21) of a transformer (2) is deformed under the influence of the physical quantity and thus produces a magnetostrictive effect, - wherein, within the scope of the method, a first tap voltage is tapped from a first secondary winding (20.1) of the transformer (2) and a first tap signal (23) is formed on the basis of this first tap voltage, - wherein, within the scope of the method, the first tap signal (23) is related to a reference signal (24) in order to obtain a measurement signal (25) which is at least approximately proportional to the physical quantity, - wherein, within the scope of the method, a successive processing of the first tap signal (23) is carried out, characterized by that the processing comprises a bandwidth reduction (11) of the first tap signal (23). [13] A computer program comprising steps which, when executed on a computer, cause the computer to at least partially carry out a method according to claim 12. [14] Computer-readable medium, characterized bythat the computer-readable medium comprises computer program code for carrying out at least one step, preferably a plurality of steps, of a method according to claim 12.

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