System for controlling a device provided with at least one redundant sensor for detecting and isolating failures in one of the sensors

Abstract

The invention relates to a system for controlling a device (1) provided with at least one equipment item (1i), the control system comprising at least one sensor (3) capable of measuring operating quantities of the device, and two specific channels (3ia, 3ib) for measuring a redundant sensor for each equipment item (1i), at least one embedded control means (2a, 2b) configured to determine a command intended for at least one equipment item (1i) as a function of the at least one measurement of the operating quantity of the device (1) and a selected measurement of the controlled equipment item (1i), the control system further comprising a calculating means (5) configured to determine the selected measurement of the at least one controlled equipment item (1i) by means of a Kalman filter observer as a function of the at least one measurement of the operating quantity of the device (1) and the measurements of the two specific channels (3ia, 3ib) for measuring a redundant sensor for the controlled equipment item (1i).

Description

[0001] DESCRIPTION

[0002] TITLE: Control system for a device equipped with at least one redundant sensor for detecting and isolating failures of one of said sensors.

[0003] Technical field

[0004] The technical field of the invention is control systems, and more specifically observer control systems.

[0005] Previous techniques

[0006] State-of-the-art aircraft engine control systems do not allow for the localization of a bias or drift in one of the measurement channels of a redundant sensor. Indeed, during a cross-check failure, determined by a difference between measurement channels greater than a threshold, an arbitrary choice is made of the channel with the minimum value, the channel with the maximum value, or an average of the two measurement channels. There is therefore a risk of continuing to use an erroneous measurement or a value dependent on this erroneous measurement. State-of-the-art control systems only allow the failure to be detected and not localized.

[0007] The following documents are known from the state of the prior art.

[0008] Document US20200201312 discloses a technology for isolating and detecting faults in aeronautical anemometric sensors (Total pressure, Static pressure, etc.). To achieve this, it is described to use a bank of KALMAN filters and its residuals (i.e. deviations between the estimated measurement and the actual measurement) coupled with a truth table to detect and isolate a faulty sensor or to reconfigure it on its model in the event of a fault.

[0009] Document CN 1 101 18128 describes a similar teaching but based on a particular formatting of the residues (WSSR: Weighted Sum of Squares of Residuals) for isolation and detection. Document US2009043447 also describes a similar teaching, but based on different indicators (delta on averages of the evolutions of the states and / or the residues) to detect and isolate faults. In addition, in the case where the faulty sensor cannot be isolated, a probabilistic approach (occurrence of faults) is used.

[0010] These different state-of-the-art documents allow to detect the fault of a sensor among a set of sensors measuring different physical quantities. Moreover, these different documents are based on different Kalman filter architectures in the form of "banks": several different Kalman filters are used with the same sensors and the interpretation of the residuals (i.e. differences between the model outputs and the sensor measurements) allows to detect the sensor of a physical quantity that is faulty.

[0011] We also know the document BM De Silva et al. disclosing a system for determining the failure of a sensor based on a Kalman filter.

[0012] The document describes the determination of estimated values ​​of the measurements of a redundant sensor, and the determination of a failure through the evolution of a moving average of the innovation matrix. The system includes offline steps of calibrating a model and training a decision tree based on a training set, and online steps, applied to sensor measurements. During the online steps, expected values ​​are determined by the decision tree using the system determined during the offline steps, then transmitting the expected values ​​to the decision tree to obtain a prediction concerning the failure of a sensor in the set of sensors. The document is thus limited to the detection of the failure of a sensor, and does not mention the case of measurement channels of a redundant sensor or the control of an actuator.

[0013] The technical problem to be solved is how to detect a failure of one of the measurement channels of a redundant sensor and exclude the measurement channel of the failed redundant sensor from a control by a Kalman filter type observer. Description of the invention

[0014] An object of the invention is a system for controlling a device provided with at least one piece of equipment, the control system comprising at least one sensor capable of each measuring an operating quantity of the device, and two measurement channels of the redundant sensor for each piece of equipment, at least one nested control means configured to determine a command to the at least one piece of equipment as a function of the measurement of at least one operating quantity of the device and a measurement selected for the controlled equipment, the control system further comprising a calculation means configured to determine the measurement selected for the at least one controlled equipment, by an observer of the Kalman filter type, as a function of the at least one measurement of the operating quantity of the device and the measurements of the measurement channels of the redundant sensor for the controlled equipment,the calculation means being further configured to detect a failure of one of the measurement channels of the specific redundant sensor so as to exclude the measurement channel therefrom.

[0015] The device may comprise at least two devices, the measurement selected for the at least two devices being determined by the same Kalman filter observer.

[0016] The calculation method may include:

[0017] • an observer by Kalman filter determining an estimate of a bias of the first measurement channel and an estimate of a bias of the second measurement channel as a function of at least one measurement of the operating quantity of the device, of the first measurement channel of the redundant sensor and of the second measurement channel of the same redundant sensor,

[0018] • a comparison means configured to emit a selection signal as a function of the results of comparison of each bias estimate with a first predetermined threshold, of the result of the comparison of the absolute value of the difference of the two measurement channels with a second predetermined threshold and of the bias estimates between them, and • a selection device configured to transmit the selected measurement equal to the measurement of the first measurement channel of the redundant sensor, to the measurement of the second measurement channel of the redundant sensor or to the average of the measurements of the two measurement channels of the redundant sensor as a function of a selection signal.

[0019] The selection device may comprise a calculation means configured to perform the average of the measurement of the first measurement channel and the measurement of the second measurement channel, the selection device also comprising a logic gate receiving as input on the one hand the selection signal and on the other hand the measurement of the first measurement channel, the measurement of the second measurement channel and the average of the measurements of the measurement channels, the logic gate being configured to emit the selected measurement equal to one of the values ​​received as input as a function of the selection signal.

[0020] The comparison tool can be configured to perform the following steps:

[0021] • when the absolute value of the difference between the measurement of the first measurement channel and the measurement of the second measurement channel is less than a second predetermined threshold or none of the bias estimates is greater than a first predetermined threshold, the selection signal emitted indicates to the selection device to transmit a selected measurement equal to the average of the measurements of the measurement channels of the redundant sensor,

[0022] • when the absolute value of the difference between the measurement of the first measurement channel and the measurement of the second measurement channel is greater than a second predetermined threshold and the estimate of the bias of the first measurement channel is not greater than a first threshold, and the estimate of the bias of the second measurement channel is greater than the first threshold, the selection signal emitted indicates to the selection device to transmit a selected measurement equal to the measurement of the first measurement channel of the redundant sensor,

[0023] • when the absolute value of the difference between the measurement of the first measurement channel and the measurement of the second measurement channel is greater than a second predetermined threshold and the estimate of the bias of the first measurement channel is greater than the first threshold, and the estimate of the bias of the second measurement channel is not greater than the first threshold, the selection signal emitted indicates to the selection device to transmit a selected measurement equal to the measurement of the second measurement channel of the redundant sensor,

[0024] • when the absolute value of the difference between the measurement of the first measurement channel and the measurement of the second measurement channel is greater than a second predetermined threshold and the estimate of the bias of the first measurement channel is greater than the first threshold, when the estimate of the bias of the second measurement channel is greater than the first threshold, and when the estimate of the bias of the first measurement channel is not greater than the estimate of the bias of the second measurement channel, the selection signal emitted indicates to the selection device to transmit a selected measurement equal to the measurement of the first measurement channel of the redundant sensor,

[0025] • when the absolute value of the difference between the measurement of the first measurement channel and the measurement of the second measurement channel is greater than a second predetermined threshold and the estimate of the bias of the first measurement channel is greater than the first threshold, when the estimate of the bias of the second measurement channel is greater than the first threshold, and when the estimate of the bias of the first measurement channel is greater than the estimate of the bias of the second measurement channel, the selection signal emitted indicates to the selection device to transmit a selected measurement equal to the measurement of the second measurement channel of the redundant sensor.The comparison means can be configured to carry out the following steps: the bias estimates are stored at the moment when it is determined that the difference in absolute value between the measurement of the first measurement channel and the measurement of the second measurement channel is greater than a predetermined threshold and a selection signal is emitted indicating to the selection device to transmit a selected measurement equal to the measurement of the measurement channel of the redundant sensor for which the absolute value of its bias estimate is the lowest.

[0026] The comparison means can be configured to carry out the following steps: the bias estimates are stored over time on a sliding window, when a predefined number of values ​​are stored, the variance or standard deviation of the bias estimates of the first measurement channel is determined and the variance or standard deviation of the bias estimates of the second measurement channel is determined, the variances or standard deviations obtained are compared and a selection signal is emitted indicating to the selection device to transmit a selected measurement equal to the measurement of the measurement channel of the redundant sensor for which the variance or standard deviation of the associated bias estimate takes the lowest value.

[0027] The comparison means can be configured to carry out the following steps: the bias estimates are stored over time, when a predefined number of values ​​are stored, the gradient of the bias estimates of the first measurement channel is determined and the gradient of the bias estimates of the second measurement channel is determined, the gradients obtained are compared and a selection signal is emitted indicating to the selection device (5c) to transmit a selected measurement equal to the measurement channel of the redundant sensor for which the gradient of the associated bias estimates is the lowest.

[0028] The controlled equipment may be an actuator, the system then comprising an observer by Kalman filter determining an estimate of the bias of the first measurement channel and an estimate of the bias of the second measurement channel as a function of at least one measurement of the operating quantity of the device, of the measurement of the first measurement channel of the redundant sensor and of the measurement of the second measurement channel of the redundant sensor, a detection device comprising:

[0029] • a first subtractor determining the difference between the measurement of the first measurement channel of the redundant sensor and the measurement of the second measurement channel of the redundant sensor,

[0030] • a first comparison means determining whether the difference between the measurement of the first measurement channel of the redundant sensor and the measurement of the second measurement channel of the redundant sensor is less than a second threshold, if this is the case the first comparison means emits a first signal to a logic gate,

[0031] • a second comparison means determining whether the estimate of the bias of the first measurement channel is greater than a third threshold, if this is the case the second comparison means emits a first signal to the logic gate,

[0032] • a third comparison means determining whether the estimate of the bias of the second measurement channel is greater than the third threshold, if this is the case the third comparison means emits a first signal to the logic gate,

[0033] • a second subtractor determining the difference between the estimate of the bias of the first measurement channel and the estimate of the bias of the second measurement channel,

[0034] • a fourth comparison means determining whether the difference between the estimate of the bias of the first measurement channel and the estimate of the bias of the second measurement channel is greater than a fourth threshold, with a hysteresis taking into account the precision of the two measurement channels of the redundant sensor, if this is the case the fourth comparison means emits a first signal to the logic gate, • the logic gate transmitting a first signal when all its inputs receive a first signal, the logic gate transmitting a second signal when all its inputs do not receive the first signal, which makes it possible to detect the actuation failure.

[0035] The device may be an aircraft engine and the measurement channels of the redundant sensor measure the position of the variable geometry cylinders, the position of the fuel metering valve, the variable timings of the stators of the engine's high pressure compressor, the measurement of the temperature at the inlet of the engine's high pressure compressor, or the measurement of the static pressure at the inlet of the engine's combustion chamber.

[0036] Another object of the invention is a method for controlling a device provided with at least one piece of equipment, at least one sensor capable of measuring an operating quantity of the device, and redundant sensor measurement channels for each piece of equipment, the control method comprising the following steps:

[0037] • a command is determined for at least one piece of equipment based on at least one measurement of the operating quantity of the device and a measurement selected for the equipment being controlled, then

[0038] • the measurement selected for the at least one controlled equipment is determined by a Kalman filter observer, as a function of the at least one measurement of the operating quantity of the device and the measurements of the measurement channels of the redundant sensor for the controlled equipment.

[0039] Another subject of the invention is an aircraft provided with a control system or comprising a control method as described above.

[0040] Brief description of the drawings

[0041] Other aims, characteristics and advantages of the invention will appear on reading the following description, given solely by way of non-limiting example and made with reference to the appended drawings in which:

[0042] - Figure 1 illustrates the main elements of a control system based on a Kalman filter,

[0043] - Figure 2 illustrates the main elements of the calculation means configured to determine the bias estimates in the control system according to the invention, and

[0044] - Figure 3 illustrates an alternative selection device applied to the detection of actuation failures in the control system according to the invention.

[0045] Detailed description

[0046] The control system according to the invention is based on the use of the same Kalman filter (but fed by different measurement channels) to detect and locate a simple failure of a redundant sensor in order to accommodate the acquisition on the healthy channel instead of arbitrarily choosing a channel and potentially selecting the wrong channel. In an application to an aircraft, and to the control of the engine of an aircraft, it is then possible to avoid an engine event, such as a loss of thrust control LOTC (acronym "Loss of Thrust Control").

[0047] Figure 1 illustrates the main elements of a control system based on a Kalman filter type observer.

[0048] A device 1, such as an engine for an aircraft, is controlled by a control means 2a, 2b as a function of the difference between a setpoint CS of an operating parameter of the device 1 (for example, the rotation speed in the case of an engine) and a measurement Y by a sensor 3 of the operating parameter of the device 1 corresponding to the setpoint CS.

[0049] The difference between the CS setpoint and the Y measurement is determined by means of a subtractor 4.

[0050] The first control means 2a may be an open-loop or closed-loop control means and makes it possible to determine the control u c The second control means 2b is a closed-loop control means.

[0051] More precisely, the first control means 2a makes it possible to determine a control instruction u c as a function of the difference between the setpoint CS and the measurement Y when the first control means 2a is a closed-loop control means. The first control means 2a makes it possible to determine a control setpoint u c as a function of the measurement Y when the first control means 2a is an open-loop control means. This control instruction u c is received by a second control means 2b in order to determine a command u of at least one device li taking into account a selected measurement us received from a calculation means 5 comprising an observer based on a Kalman filter 5a.

[0052] It will be understood that the use of two control means 2a, 2b makes it possible to control several separate pieces of equipment li acting on the devices as a function of the measurement Y and / or the setpoint CS according to the structure of the first control means 2a. In the case of an aeronautical engine controlled in this way, the pieces of equipment li controlled may be the fuel meter or the variable geometry blades of said engine. These pieces of equipment contribute to the operation of the engine, and to the realization of the control, for example the rotation speed of the engine. It is thus understood that to realize the setpoint CS through the measurement Y, the control u is of the vector type, and comprises a measurement selected for each piece of equipment li of the device 1. It should be noted that the quantities u c , u s , CS, Y, UL and u x can be vectors.

[0053] In order to ensure that each device li carries out the command determined by the second control means 2b, measurement channels 3ia, 3ib specific to each device li are used. Each pair of measurement channels 3ia, 3ib comes from the redundancy of a measurement sensor and its acquisition chain. They thus measure the same quantity so that the measurement is always available even in the event of failure of one of the measurement channels 3ia, 3ib of a specific redundant sensor. The measurements of the first measurement channel 3ia of several sensors (with i varying from 1 to j) can be concatenated in the vector UL . The measurements of the second measurement channel 3ib of several sensors can be concatenated in the vector u x . In Figure 1, a single piece of equipment li is illustrated for the sake of readability. It will be understood that an aircraft engine is generally equipped with multiple pieces of equipment li, each equipped with a pair of specific redundant sensors 3ia, 3ib.

[0054] However, this redundancy then poses the problem of determining the measurement channels 3ia,3ib to be taken into account in the calculation of the selected measurement u s to be transmitted to the second control means 2b.

[0055] Indeed, simple cases such as the absence of a signal or identical signals can be handled with logical operators. However, more complex cases such as drift or bias of a sensor measurement channel cannot be handled in this way.

[0056] The calculation means 5 receives as input the measurements UL,UX of the measurement channels 3ia,3ib of the redundant sensor and one or more measurements Y of the sensor 3. It outputs the selected measurement signal u s to the second control means 2b. The calculation means 5 comprises an observer based on a Kalman filter, making it possible to determine the selected measurement u saccording to the signals of the sensors UL,UX,Y. The observer is built from a model representative of the observed device 1 and of at least one piece of equipment li and makes it possible to isolate a faulty measurement channel coming from one of the measurement channels 3ia,3ib of the redundant sensor measuring each piece of equipment li.

[0057] The selected measurement us is obtained by adding additive biases on the inputs UL, ux. The Kalman filter then allows, by varying in real time the additive biases on each of the model inputs, to converge the model outputs with the motor measurements Y. The convergence makes it possible to obtain a zero residue. The biases obtained then directly represent the difference between the real measurement of the controlled equipment (determined by observation via its effect on the device) and the chosen measurement UL, UX from one of the measurement channels 3ia, 3ib of the sensor.

[0058] The adjustment of the filter performance (gains) is optimally achieved through the resolution of a standard problem (e.g., RICCATI algebraic equation).

[0059] More precisely, the calculation means 5 carries out the estimation of the biases associated with each measurement channel 3ia or 3ib of the redundant sensor.

[0060] When the bias estimate associated with a 3ia or 3ib measurement channel of the redundant sensor exceeds a first predefined maximum threshold, the 3ia or 3ib measurement channel of the redundant sensor is declared to be faulty. The observer then uses the measurements provided by the other 3ia or 3ib measurement channel of the redundant sensor. This arbitration can be done in the form of a truth table.

[0061] Figure 2 illustrates the main elements of the calculation means 5.

[0062] The calculation means 5 comprises a Kalman filter observer referenced 5a, a comparison means 5b, and a selection device referenced 5c.

[0063] The observer 5a makes it possible to determine, taking into account one or more measurements Y, an estimate of the bias of the first measurement channel ûi corresponding to the measurement ui of the first measurement channel 3ia of the redundant sensor and an estimate of the bias of the second measurement channel ûx corresponding to the measurement u x of the second measuring channel 3ib of the redundant sensor.

[0064] The comparison means 5b is configured to determine a selection signal, denoted sel, as a function of the comparison of the estimate of the bias of the first measurement channel ûi with a first threshold a, of the estimate of the bias of the second measurement channel ûx with a first threshold a, and of the estimate of the bias of the first measurement channel ûi with the estimate of the bias of the second measurement channel ûx. The Boolean signals associated with these comparisons are transmitted to a predetermined truth table so as to determine the selection signal sel of the value to be transmitted as the selected measurement us. For example, if the value 1 is assigned to a verified comparison, and the value 0 is assigned to a comparison which is not verified, then the truth table comprises the values ​​illustrated by the table [Table 1],

[0065] [Table 1]

[0066] The first three columns correspond to the table entries, the last column corresponding to the selection signal determined by the table.

[0067] Thus when none of the bias estimates is greater than the first predetermined threshold a, the selected value is the average of the measurements of the measurement channels (3ia,3ib) (ui+u x ) / 2.

[0068] When the bias estimate of the first measurement channel ûi is not greater than the first threshold a, and the bias estimate of the second measurement channel ûx is greater than the first threshold a, the selected value is the measurement of the first measurement channel ui.

[0069] When the bias estimate of the first measurement channel ûi is greater than the first threshold a, and the bias estimate of the second measurement channel ûx is not greater than the first threshold a, the selected value is the measurement u x of the second measuring channel.

[0070] When the bias estimate of the first measurement channel ûi is greater than the first threshold a, when the bias estimate of the second measurement channel ûx is greater than the first threshold a, and when the bias estimate of the first measurement channel ûi is not greater than the bias estimate of the second measurement channel ûx, the selected value is the first measurement of the first measurement channel ui.

[0071] When the bias estimate of the first measurement channel ûi is greater than the first threshold a, when the bias estimate of the second measurement channel ûx is greater than the first threshold a, and when the bias estimate of the first measurement channel ûi is greater than the bias estimate of the second measurement channel ûx, the selected value is the second measurement u x of the second measuring channel.

[0072] Depending on the result of the comparison, the sel selection signal is then transmitted to the selection device 5c also receiving as input the measurement ui of the first measurement channel (3ia) and the measurement Ux of the second measurement channel (3ib).

[0073] The selection device 5c comprises a calculation means 5d configured to carry out the average of the measurement ui of the first measurement channel (3ia) and of the measurement u x of the second measuring channel (3ib).

[0074] The selection device 5c also comprises a logic gate 5e receiving as input on the one hand the selection signal sel and on the other hand the measurement ui of the first measurement channel (3ia), the measurement Ux of the second measurement channel (3 ib) and the average of the measurement ui of the first measurement channel (3ia) and the measurement u x of the second measuring channel (3ib).

[0075] Depending on the sel selection signal received and the comparison of the absolute value of the difference between the measurement ui of the first measurement channel (3ia) and the measurement u x of the second measuring channel (3ib) with respect to a second predefined threshold P, the selection device 5c transmits the measurement ui of the first measuring channel (3ia), the measurement u x of the second measuring channel (3ib) or the average of the measurement ui of the first measuring channel (3ia) and the measurement u x from the second measuring channel (3ib) in the form of the selected measuring signal us.

[0076] The following [Table 2] illustrates the truth table resulting from the actions of the comparison means 5b and the selection device 5c. [Table 2]

[0077] The control system has been described in relation to a single quantity measured by two specific measurement channels 3ia, 3ib of a redundant sensor. However, the control system can be extended to at least two quantities each measured by two specific measurement channels of redundant sensors. In this case, the same observer 5a with Kalman filter is used to determine the estimation of the bias of the measurement channels for each quantity taken into account.

[0078] For each quantity, we then have two bias estimates, a means of comparison with its own truth table and with its own comparison threshold, as well as a means of selection.

[0079] The control system allows:

[0080] • to isolate, for each redundant sensor, the faulty channel from the healthy channel and thus be able to reconfigure itself,

[0081] • to use the same Kalman filter fed by different measurement channels. Thus, unlike the state of the art which uses a bank of different Kalman filters, this makes it possible to optimize the control system (reducing the impact on memory or CPU load)

[0082] • to obtain an estimate of the bias directly dependent on the measurements and easily interpretable subsequently (unlike the residuals used in the state of the art)

[0083] Applied to an aircraft, and in particular to the control of an aircraft engine, the control system makes it possible to be robust to failure during flight and to provide a diagnosis for replacement at the end of the mission.

[0084] In a first alternative embodiment, the control system according to the invention makes it possible to take into account the precision of the model embedded in the Kalman filter to distinguish it from the drift effects of the measurement channels 3ia, 3ib of the redundant sensor.

[0085] The model embedded in the Kalman Filter has a certain precision which directly impacts the bias estimation performance. Indeed, if the embedded model is not perfect, the bias estimation by the Kalman Filter can be decomposed as follows:

[0086] Û — U + £ mdi

[0087] With :

[0088] • û - Bias estimated by the Kalman Filter but actual seen by the physical system Modeling error

[0089] Unlike the previous embodiment in which the bias estimate is compared “in absolute” to a first threshold, this alternative embodiment comprises a “in relative” comparison of the absolute value of the local bias estimate (|û L |) and cross ( |û x |).

[0090] This alternative embodiment is based on the observation that the modeling error varies little over time. This may be, for example, the aging of the device 1. This modeling error is also identical in the bias estimate corresponding to the measurement channels 3ia, 3ib of the redundant sensor because these bias estimates are estimated from the same Kalman Filter (and therefore with the same embedded model).

[0091] Indeed, in the example where the perturbations |û L | and |û x | are

[0092] With :

[0093] • û L~ Estimation of bias by the Kalman Filter from local channel measurements • û x - Estimation of bias by the Kalman Filter from cross channel measurements

[0094] • u L ~ Actual bias seen on local channel measurement

[0095] • u x ~ Actual bias seen on cross track measurement m _ m _ Modeling error (identical)

[0096] Therefore, the sign of the comparison |û L | — |û x | determines which measurement is furthest from the actual physical quantity and therefore which measurement has drifted despite the modeling error. The selection signal emitted allows the value from the sensor that has drifted too much to be discarded.

[0097] In this embodiment, the bias estimates are stored at the time when it is determined that the absolute value difference between the first measurement channel ul and the second measurement channel u is greater than the threshold P, in order to have a reference. The sign of the comparison |û is then determined L | — |û x |.

[0098] If the sign is positive, a selection signal is emitted allowing the second measurement ux to be chosen as the selected measurement us.

[0099] If the sign is negative, a selection signal is emitted allowing the first UL measurement to be chosen as the selected measurement us.

[0100] In a second alternative embodiment, the control system according to the invention makes it possible to compare the evolution of the variance or the standard deviation of the two biases to prevent dispersion effects from masking the failure of the specific sensors.

[0101] As presented above, the bias estimates include a common modeling error. Apart from the inaccuracy of the measurements of the specific redundant sensors 3ia,3ib, the evolution of the variance (or standard deviation) of the two bias estimates is therefore almost identical. Consequently, if the evolution of the variance (or standard deviation) of one of the two bias estimates is much faster than that of the other bias estimate, it is because the measurement associated with this bias estimate is undergoing a drift. The corresponding measurement channel is therefore faulty.

[0102] This embodiment makes it possible in particular to cover the case where the fault has an effect on the measurement compensating for the modeling error and potentially making it more difficult to locate the fault with the first alternative embodiment.

[0103] To achieve this, we store the bias estimates û on a sliding window L , û xat each iteration of the observer by Kalman filter. When a predefined number of values ​​are stored, the variance or standard deviation of the bias estimates of the first measurement channel is determined û L and we determine the variance or standard deviation of the bias estimates of the second measurement channel û x .

[0104] The variances or standard deviations obtained are compared and a selection signal is issued designating the measurement channel of the redundant sensor for which the variance or standard deviation of the associated bias estimate takes the lowest value.

[0105] In a third alternative embodiment, the control system according to the invention makes it possible to compare the evolution of the gradient of the two bias estimates to take into account drifts in the system.

[0106] As for the second alternative embodiment, the bias estimates û are stored L , û xat each iteration of the observer by Kalman filter. When a predefined number of values ​​are stored, the gradient of the bias estimates of the first measurement channel is determined û L and we determine the gradient of the bias estimates of the second measurement channel û x .

[0107] The gradients thus obtained are compared and a selection signal is emitted designating the measurement channel of the redundant sensor for which the gradient of the associated bias estimate is the lowest.

[0108] It is also possible to configure the control system according to the invention to detect actuation failures. In the case of an aeronautical engine, one can cite the actuation failures of a fuel meter. To achieve this, the outputs of the Kalman filter observer type device 5a can be reused as input to the detection device 6, illustrated in Figure 3.

[0109] The detection device 6 comprises a first subtractor 6a determining the difference between the measurement of the first measurement channel 3ia of the redundant sensor and the measurement of the second measurement channel 3ib of the same redundant sensor.

[0110] A first comparison means 6b determines whether the difference between the measurement of the first measurement channel 3ia of the redundant sensor and the measurement of the second measurement channel 3ib of the same redundant sensor is less than a second threshold S2. If this is the case, the first comparison means then emits a first signal to the logic gate 6g.

[0111] A second comparison means 6c determines whether the estimate of the bias of the first measurement channel û L is greater than a third threshold S3. If this is the case, the second comparison means 6c emits a first signal to the logic gate 6g.

[0112] A third comparison means 6d determines whether the estimate of the bias of the second measurement channel û x is greater than the third threshold S3. If this is the case, the third comparison means 6d emits a first signal to the logic gate 6g.

[0113] A second subtractor 6e determines the difference between the bias estimate of the first measurement channel û L and the estimation of the bias of the second measurement channel û x .

[0114] A fourth comparison means 6f determines whether the difference between the bias estimate of the first measurement channel û L and the estimation of the bias of the second measurement channel û xis less than a fourth threshold S4, with a hysteresis taking into account the accuracy of the two measurement channels of the redundant sensor. Indeed, in the event of a failure of the actuator, the estimation of the two biases is supposed to be almost identical to the measurement error of the measurement channels of the redundant sensor. The presence of the hysteresis makes it possible to take this into account. If this is the case, the fourth comparison means 6f emits a first signal to the logic gate 6g. The logic gate 6g transmits a signal when all its inputs receive a first signal, and no signal otherwise, which makes it possible to detect the actuation failure.The control system according to the invention can be configured to be applied to specific redundant sensors measuring the position of variable geometry cylinders LVDT (acronym for "Linear Variable Differential Transform") including in particular a fuel metering valve FMV (acronym for "Fuel Metering Valve") and variable timings of the stators of the high pressure compressor VSV (acronym for "Variable Stator Valve"). It can also be applied to the measurement of the temperature at the inlet of the high pressure compressor, or to the measurement of static pressure at the inlet of the combustion chamber of an aircraft engine.

Claims

DEMANDS 1. Control system of a device (1) equipped with at least one piece of equipment (li), the control system comprising at least one sensor (3) capable of measuring each one operating quantity of the device, and two measurement channels (3ia,3ib) of the redundant sensor for each piece of equipment (li), at least one nested control means (2a, 2b) configured to determine a command to the at least one piece of equipment (li) as a function of the measurement of at least one operating quantity of the device (1) and a measurement selected for the controlled equipment (li), the control system further comprising a computing means (5) configured to determine the measurement selected for the at least one controlled equipment (li), by a Kalman filter-based observer, as a function of the at least one measurement of the operating quantity of the device (1) and the measurements of the measurement channels (3ia,3ib) of the redundant sensor for the controlled equipment (li),the calculation means (5) being further configured to detect a failure of one of the measurement channels (3ia,3ib) of the redundant sensor by applying a Kalman filter-based observer, as a function of at least one measurement of the operating quantity of the device (1) and the measurements of the measurement channels (3ia,3ib) of the redundant sensor for the controlled equipment (11), so as to exclude the measurement channel.

2. Control system according to claim 1, wherein the device (1) comprises at least two pieces of equipment (1i), the measurement selected for the at least two pieces of equipment being determined by the same Kalman filter-based observer.

3. Control system according to any one of claims 1 or 2, wherein the computing means (5) comprises: • a Kalman filter-type observer (5a) determining an estimate of a bias in the first measurement channel and an estimate of a bias in the second measurement channel as a function of at least one measurement of the device's operating quantity, and of the measurement in the first channel measurement of the redundant sensor and measurement of the second measurement channel of the redundant sensor, • a comparison means (5b) configured to emit a selection signal based on the results of comparing each bias estimate at a first predetermined threshold, the result of comparing the absolute value of the difference between the two measurement channels at a second predetermined threshold and the bias estimates between them, and • a selection device (5c) configured to transmit the selected measurement equal to the measurement of the first measurement channel, to the measurement of the second measurement channel or to the average of the measurements of the first measurement channel and the second measurement channel according to a selection signal.

4. Control system according to claim 3, wherein the selection device (5c) comprises a calculation means (5d) configured to perform the average of the measurement of the first measurement channel and the measurement of the second measurement channel, the selection device (5c) also comprising a logic gate (5e) receiving as input on the one hand the selection signal and on the other hand the measurement of the first measurement channel, the measurement of the second measurement channel and the average of the measurement of the first measurement channel and the measurement of the first measurement channel, the logic gate (5e) being configured to output the selected measurement equal to one of the values ​​received as input as a function of the selection signal.

5. A system according to any one of claims 3 or 4, wherein the comparison means (5b) is configured to perform the following steps: • When the absolute value of the difference between the measurement of the first measurement channel and the measurement of the second measurement channel is less than a second predetermined threshold, or neither of the bias estimates is greater than a first predetermined threshold, the emitted selection signal instructs the selection device (5c) to transmit a measurement selected equal to the average of the measurements from the measurement channels (3 ia, 3 ib), • when the absolute value of the difference between the measurement of the first measurement channel and the measurement of the second measurement channel is greater than a second predetermined threshold and the estimation of the bias of the first measurement channel is not greater than a first threshold, and the estimation of the bias of the second measurement channel is greater than the first threshold, the selection signal emitted instructs the selection device (5c) to transmit a selected measurement equal to the measurement of the first measurement channel (3ia), • when the absolute value of the difference between the measurement of the first measurement channel and the measurement of the second measurement channel is greater than a second predetermined threshold and the estimation of the bias of the first measurement channel is greater than the first threshold, and the estimation of the bias of the second measurement channel is not greater than the first threshold, the selection signal emitted instructs the selection device (5c) to transmit a selected measurement equal to the measurement of the second measurement channel (3ib), • when the absolute value of the difference between the measurement of the first measurement channel and the measurement of the second measurement channel is greater than a second predetermined threshold and the estimate of the bias of the first measurement channel is greater than the first threshold, when the estimate of the bias of the second measurement channel is greater than the first threshold, and when the estimate of the bias of the first measurement channel is not greater than the estimate of the bias of the second measurement channel, the selection signal emitted instructs the selection device (5c) to transmit a selected measurement equal to the measurement of the first measurement channel (3ia), • when the absolute value of the difference between the measurement of the first measurement channel and the measurement of the second measurement channel is greater than a second predetermined threshold and the estimation of the bias of the first measurement channel is greater than the first threshold, when the estimation of the bias of the second measurement channel is greater than the first threshold, and when the estimation of the bias of the first measurement channel is greater than the estimation of the bias of the second measurement channel, the selection signal emitted instructs the selection device (5c) to transmit a selected measurement equal to the measurement of the second measurement channel (3ib).

6. Control system according to any one of the preceding claims, wherein the comparison means (5b) is configured to perform the following steps: the bias estimates are stored when it is determined that the difference in absolute value between the measurement of the first measurement channel and the measurement of the second measurement channel is greater than a predetermined threshold and a selection signal is emitted instructing the selection device (5c) to transmit a selected measurement equal to the measurement of the measurement channel of the redundant sensor for which the absolute value of its bias estimate is the lowest.

7. Control system according to any one of the preceding claims, wherein the comparison means (5b) is configured to perform the following steps: the bias estimates are stored on a sliding window over time; when a predefined number of values ​​are stored, the variance or standard deviation of the bias estimates of the first measurement channel is determined, and the variance or standard deviation of the bias estimates of the second measurement channel is determined; the variances or standard deviations obtained are compared, and a selection signal is emitted instructing the selection device (5c) to transmit a selected measurement equal to the measurement of the measurement channel of the redundant sensor for which the variance or standard deviation of the associated bias estimate takes the lowest value.

8. Control system according to any one of the preceding claims, wherein the comparison means (5b) is configured to perform the following steps: the bias estimates are stored over time, when a predefined number of values ​​are stored, the gradient of the bias estimates of the first measurement channel is determined and the gradient of the bias estimates of the second measurement channel is determined, the gradients obtained are compared and a selection signal is emitted instructing the selection device (5c) to transmit a selected measurement equal to the measurement of the measurement channel of the redundant sensor for which the gradient of the associated bias estimate is the lowest.

9. Control system according to any one of claims 1 or 2, wherein the controlled equipment (1) is an actuator, the system includes a Kalman filter observer (5a) determining an estimate of a bias of the first measurement channel and an estimate of a bias of the second measurement channel as a function of at least one measurement of the operating quantity of the device, the measurement of the first measurement channel of the redundant sensor and the measurement of the second measurement channel of the redundant sensor, a sensing device (6) comprising: • a first subtractor (6a) determining the difference between the first measurement channel (3ia) of the redundant sensor and the second measurement channel (3ib) of the redundant sensor, • a first comparison means (6b) determining whether the difference between the measurement of the first measurement channel (3ia) of the redundant sensor and the measurement of the second measurement channel (3ib) of the redundant sensor is less than a second threshold, if so the first comparison means emits a first signal to a logic gate (6g), • a second comparison means (6c) determining whether the bias estimate of the first measurement channel is greater than a third threshold; if so, the second comparison means (6c) emits a first signal to the logic gate (6g), • a third comparison means (6d) determining whether the bias estimate of the second measurement channel is greater than the third threshold; if so, the third comparison means (6d) emits a first signal to the logic gate (6g), • a second subtractor (6e) determining the difference between the bias estimate of the first measurement channel and the bias estimate of the second measurement channel, • a fourth comparison means (6f) determining whether the difference between the bias estimate of the first measurement channel and the bias estimate of the second measurement channel is less than a fourth threshold, by a hysteresis taking into account the accuracy of the measurement channels of the redundant sensor, if this is the case the fourth comparison means (6f) emits a first signal to the logic gate (6g), • the logic gate (6g) transmitting a signal when all its inputs receive a first signal, the logic gate (6g) not transmitting a signal when at least one of its inputs does not receive the first signal, which allows detection of an actuator failure.

10. Control system according to any one of the preceding claims, wherein the device (1) is an aircraft engine and the measurement channels (3ia,3ib) of the redundant sensor measure the position of the variable geometry cylinders, the position of the fuel metering valve, the variable stator settings of the engine's high-pressure compressor, the temperature measurement at the inlet of the engine's high-pressure compressor, or the static pressure measurement at the inlet of the engine's combustion chamber. 1.

1. Method for controlling a device (1) equipped with at least one piece of equipment (li), at least one sensor (3) capable of measuring an operating quantity of the device (1), and measurement channels (3ia, 3ib) of the redundant sensor for each piece of equipment (li), the control method comprising the following steps: • a command is determined for at least one piece of equipment (li) as a function of at least one measurement of the operating quantity of the device (1) and a measurement selected for the controlled equipment (li), then the measurement selected for the at least one controlled equipment (li) is determined, by a Kalman filter observer, as a function of at least one measurement of the operating quantity of the device (1) and the measurements of the measurement channels (3ia,3ib) of the redundant sensor for the controlled equipment (li).

12. Aircraft equipped with a control system according to any one of claims 1 to 10 or comprising a control method according to claim 11.

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