DE102017003657A1 - Method for evaluating a sensor system and device for carrying out a corresponding method - Google Patents

Abstract

The invention relates to a method for evaluating a sensor system having at least one passive inductive proximity sensor and to a device for carrying out a corresponding method.

Description

The invention relates to a method for evaluating a sensor system having at least one passive inductive proximity sensor and to a device for carrying out a corresponding method.

Passive inductive proximity sensors or so-called proximity sensors are based on a change in the inductance as a function of the presence or absence of a ferromagnetic material or a target in the region of the proximity sensor. These sensors are used in the field of aircraft applications, for example for the detection / measurement of the aircraft weight or the weight-on-wheel signal or for the detection of an aircraft landing gear position.

Concepts known from the prior art are based on a sinusoidal excitation of the sensor or the sensor system, wherein a phase shift contains the necessary information (such as Target Near or Target Far). This concept requires a special hardware circuit in order to build a second-order electrical resonant circuit while generating large phase shifts due to small inductance changes. Such hardware circuits are designed specifically for the evaluation of proximity sensors.

A disadvantage of the concept known from the prior art is that the hardware circuit required especially for the evaluation of the proximity sensors is severely restricted when used for evaluating other sensor types, or that a use of the hardware circuit in conjunction with other sensors is not possible at all.

In addition, the increased hardware costs result in higher costs, greater space requirements for the sensor system and also higher error rates of the sensor system.

It is the object of the invention to provide an improved method and an improved device in which a simple hardware circuit and / or existing standardized interfaces of an electronic system can be used for the evaluation of passive inductive proximity sensors. The evaluation makes it possible to determine the position of a target, which can be monitored by the sensor system.

• • Digitales Anregen des passiven induktiven Näherungssensors;
• • Auslesen und Digitalisieren der Sprungantwort des Sensorsystems; und
• • Bestimmen einer Targetposition aus der digitalisierten Sprungantwort.

This object is achieved according to the invention by a method for evaluating a sensor system having at least one passive inductive proximity sensor, which comprises the following steps:

• • digital excitation of the passive inductive proximity sensor;
• • reading out and digitizing the step response of the sensor system; and
• • Determining a target position from the digitized step response.

According to the invention it is thus possible to evaluate an inductive proximity sensor by means of a simple hardware circuit, wherein the hardware circuit can also be used for reading out or evaluating other sensors such as resolvers, RVDT, potentiometers, temperature sensors, etc. In the present case, the term of the evaluation can refer to the readout of the step response and possibly to further steps in which the step response is processed digitally or analogously.

The method described herein broadens the generic approach to using standardized and configurable interfaces in per se known methods for evaluating passive inductive proximity switches. With the help of standardized hardware, the possibility of reuse is increased, thereby saving development effort in the development or development of similar methods or devices.

In a preferred embodiment, it is conceivable that the digital excitation takes place in a specially selected time range in which the integration or the integral of the measured values corresponds to the step response of the electrical charge Q, which is introduced by the digital excitation in the selected time range. In this case, the term of the time range may refer to a time duration or a time period during or during which the digital excitation takes place.

In a particularly preferred embodiment, it is conceivable that the selected time range lies in the range in which the transient response of a parasitic resonant circuit has subsided. The transient process may be the response of the parasitic resonant circuit to the digital excitation. The parasitic oscillating circuit itself may comprise, for example, cables or other components electronically coupled to the passive inductive proximity sensor.

In a further preferred embodiment, it is conceivable that the selected time range lies in the range in which the change in the current increase due to an inductance is still sufficiently large. By the sufficiently large current increase, it can be meant that the current increase in the first third of the selected time range is at least as great as the current increase in the last two-thirds of the time range. It is also conceivable that the current increase in the first quarter of the measured time range is at least as great as in the last three quarters of the measured time range.

In a particularly preferred embodiment, it is conceivable that the parasitic oscillatory circuit is decisively determined by the lines, in particular cables, connected to the passive inductive proximity sensor.

In a further preferred embodiment, it is conceivable that the digital excitation is an excitation with a constant value and / or that a temperature effect affecting the read-out step response is digitally compensated. In this case, it is conceivable that during the selected time range, for example, a current that changes only negligibly or negligibly is fed into the passive inductive proximity sensor.

In a further preferred embodiment, it is conceivable that the evaluation is carried out in a steady state of the system. This advantageously makes it possible to deduce the resistance conditions in the electrical system, which makes it possible to compensate for the influence of the resistance on the measured charge. Reading in the steady state can then be carried out if a compensation of the temperature effect is to take place. If the method determines a measured variable without appropriate compensation, the reading takes place in the non-steady state.

The invention is further directed to a device adapted to carry out a method according to any one of claims 1 to 7, the device comprising an exciting means for generating a digital excitation.

In a preferred embodiment, the device may further comprise an evaluation device which is set up to evaluate different sensor systems. According to such an embodiment, other than the passive inductive proximity sensor comprehensive sensor systems can be evaluated alternatively or simultaneously.

The invention is further directed to an aircraft application with at least one device according to one of claims 8 to 9.

The aircraft application can be almost any, in particular mechanical components of an aircraft such as control surfaces, chassis or the like, in which sensor systems are used.

• 1: Das elektrische Ersatzschaltbild zum erfindungsgemäßen Verfahren bzw. zur erfindungsgemäßen Vorrichtung; und
• 2: Die Sprungantwort des elektrischen Systems.

Further details and advantages of the invention are explained with reference to the embodiment shown by way of example in the figures. Showing:

• 1 : The electrical equivalent circuit diagram for the method according to the invention or for the device according to the invention; and
• 2 : The step response of the electrical system.

1 shows an electrical circuit diagram of the device according to the invention, as it can be used to carry out the method according to the invention. The passive inductive proximity sensor 1 can be stimulated digitally. The step response of the current, which depends on the resistors R and inductances L in the electrical system, is digitized in order to conclude the target position, which is determined by means of the proximity sensor 1 is detectable.

2 shows the step response of the electrical system, wherein the digital excitation and the continuous line, the step response of the current through the inductance L and by the system comprising the inductance L is shown with a dashed line.

The integration of the measured values of the step response of the current in a specially selected time range corresponds to the electrical charge Q which is introduced by the digital excitation in the selected period of time, the electrical system. The selected period is in that range in which the transient of the parasitic resonant circuit, which may be caused or influenced by the cable or lines of the system, has subsided and the change of the current increase through the inductance L is still sufficiently large.

To this applies: $${\displaystyle \underset{t=t_1}{\overset{t_2}{\Sigma }}i\left(t\right)~\tau .\tau =f\left(L.R\right)=\frac{L}{R}}$$

This charge is in turn dependent on the time constant, which is largely dominated by the inductance L _p and the ohmic resistance R _{p of} the sensor, and the input resistance R _{meas of} the transmitter.

By measuring in the steady state can be deduced the resistance ratios in the electrical system, whereby a compensation ΔQ _{R of} the influence of the resistance on the measured charge is made possible.

verglichen mit einem Referenzwert $$\text{Q}>{\text{Q}}_{\text{TH}}=\text{target far};\text{ Q}<{\text{Q}}_{\text{TH}}=\text{target near}$$

ergibt sich die gewünschte bzw. gesuchte Information des Targets $$\text{Target Near};\text{ Target Far}.$$

The resistance change, which is caused by the influence of the temperature, also allows a conclusion on the ambient temperature of the sensor, whereby the temperature dependence of the inductance ΔQ _{L can} also be compensated. Through the thus measured and digitally compensated charge $$\text{Q}={\text{Q}}_{\text{meas}}-\mathrm{\Delta }{\text{Q}}_{\text{R}}-\mathrm{\Delta }{\text{Q}}_{\text{L}}$$

compared to a reference value $$\text{Q}>{\text{Q}}_{\text{TH}}=\text{target far};\text{Q}<{\text{Q}}_{\text{TH}}=\text{target near}$$

results in the desired or searched information of the target $$\text{Target near};\text{Target Far},$$

The terms target near or target far may refer to states in which the position of a detected object, namely the target, is closer to or further from a reference position.

The desired information of the target can thus relate to a value determined by means of the passive inductive proximity sensor, which represents information about the approximation or the position of a component.

The invention can be carried out in conjunction with a Remote Electronic and Data Concentrator, wherein the universal application of the Remote Electronic and Data Concentrators invention can be extended to the readability of passive inductive proximity switches.

Other exemplary implementations may include implementing the method or apparatus in a landing gear computer to monitor inductive proximity switches to detect the landing gear position or to detect the weight-on-wheel status.

Also conceivable are designs or applications in or in connection with a flap and vane computer for checking the brake status within the high-lift system. In general, the invention is suitable for implementation in or with any type of flight control computer that requires readout of the position of an inductive proximity switch.

According to the invention, it is possible to use or provide a simple, universally usable hardware interface and thus to enable a cost-effective evaluation of passive inductive proximity sensors. Furthermore, the invention makes it possible to compensate for the temperature dependence of the sensor and to enable a rapid evaluation of the sensor values.

Claims (10)

Method for evaluating a sensor system having at least one passive inductive proximity sensor, characterized by the steps of: • digitally exciting the passive inductive proximity sensor; • reading out and digitizing the step response of the sensor system; and • determining a target position from the digitized step response. Method according to Claim 1 , characterized in that the digital excitation takes place in a specially selected time range, in which the integration or the integral of the measured values corresponds to the step response of the electrical charge Q, which is introduced in the selected time range by the digital excitation. Method according to Claim 2 , characterized in that the selected time range is in the range in which the transient of a parasitic resonant circuit has subsided. Method according to Claim 2 or 3 , characterized in that the selected time range is in the range in which the change of the current increase by an inductance is still sufficiently large. Process at least after Claim 3 , characterized in that the parasitic resonant circuit is largely determined by the connected to the passive inductive proximity sensor lines, in particular cables. Method according to one of the preceding claims, characterized in that the digital excitation is an excitation with a constant value and / or that a temperature effect affecting the read-out step response is digitally compensated. Method according to one of the preceding claims, characterized in that the reading is carried out in a steady state of the system. Apparatus adapted to perform a method according to any one of Claims 1 to 7 perform, characterized in that the device an exciting device for generating a digital excitation comprises. Device after Claim 8 , characterized in that the device comprises an evaluation device which is set up for evaluating different sensor systems. Aircraft application with at least one device according to one of Claims 8 or 9 ,

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