JP3565091B2 - Characteristics measurement method of gas concentration sensor - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method of measuring characteristics of a gas concentration sensor such as a limiting current type air-fuel ratio sensor that changes a detection current value linearly with respect to a voltage applied to a sensor element.
[0002]
[Prior art]
As a conventional technique of this type, there is a technique in which a device generally called a "gas model device" is used, and a known gas concentration environment is created with the model gas device to evaluate the characteristics of a gas concentration sensor. That is, the model gas device has a supply source for supplying various kinds of gases such as oxygen, nitrogen, and hydrogen, and a test chamber for introducing gas from each of these supply sources. The supply amount is adjusted to create a pseudo gas concentration environment. For example, when measuring the output characteristics of a limiting current type air-fuel ratio sensor (A / F sensor), an air-fuel ratio sensor is provided in the test chamber, and the sensor characteristics are determined based on the sensor output when the chamber is in a predetermined air-fuel ratio environment. Is measured.
[0003]
However, in the method for evaluating the characteristics of a gas concentration sensor using the above model gas device, it is necessary to adjust many types of gases at a fixed ratio, which causes problems such as a large-scale facility and an increase in cost.
[0004]
As another prior art, Japanese Patent Laid-Open Publication No. Hei 3-74557 is known, in which an air-fuel ratio controller adjusts a gas supplied to an engine to a predetermined air-fuel ratio, and is attached to an exhaust pipe of the engine. The values detected by the plurality of O2 sensors are read. Further, an air-fuel ratio-output characteristic comparison table is created by calculating the difference between the output of the reference O2 sensor and the output of the other O2 sensor during engine control and storing the difference in the memory. When the reference O2 sensor is deteriorated, the engine control is continued by switching to another O2 sensor.
[0005]
Further, Japanese Patent Application Laid-Open No. 2-45750 discloses a characteristic evaluation method for evaluating the characteristics of an O2 sensor (oxygen sensor) that outputs a different electromotive force signal at a stoichiometric air-fuel ratio point. The reference O2 sensor is disposed downstream of the purifier and the O2 sensor to be measured is disposed upstream of the purifier. Then, the test gas is periodically changed between the rich atmosphere and the lean atmosphere, and the time ratio between the rich signal time and the lean signal time of the O2 sensor to be measured at that time is measured to evaluate the sensor specification or to perform the measurement. The sensor characteristics are evaluated by measuring the lean voltage or output amplitude of the O2 sensor. As a result, the sensor characteristics related to the emission are measured with high accuracy.
[0006]
In both of the characteristic evaluation methods described in the above two publications, the O2 sensor that outputs an electromotive force signal that is different in the vicinity of the stoichiometric air-fuel ratio point according to the oxygen concentration is to be evaluated. Can be measured. However, when a limiting current type gas concentration sensor is to be measured, a technique for appropriately measuring sensor characteristics has not yet been established.
[0007]
[Problems to be solved by the invention]
The present invention has been made in view of the above problem, and has as its object to provide a characteristic measurement method of a gas concentration sensor that can obtain desired three-dimensional characteristics while reducing costs.
[0008]
[Means for Solving the Problems]
In the method for measuring the characteristics of the gas concentration sensor according to the first aspect, the combustion parameters in the combustion gas supply source are changed, and the gas concentration in the exhaust passage at that time is measured using a reference gas concentration meter. A correlation map with the gas concentration in the passage is created (first procedure), and then the combustion parameters are adjusted based on the created correlation map so that the inside of the exhaust passage has a predetermined gas concentration atmosphere. The current applied to the gas concentration sensor is measured by changing the applied voltage to the gas concentration sensor (second procedure), and the second procedure is repeated by changing the gas concentration in the exhaust passage (third procedure). Procedure), the relationship between the applied voltage, the sensor current, and the gas concentration is mapped based on the results measured in the second and third procedures (fourth procedure).
[0009]
According to the characteristic measuring method of the first aspect, the atmosphere in the exhaust passage is set to a known gas concentration atmosphere with reference to a correlation map between the combustion parameter of the combustion gas supply source and the gas concentration in the exhaust passage, and in that state, the gas concentration sensor is used. Since the current output information of the gas concentration sensor is acquired by changing the voltage applied to the gas concentration sensor, the relationship between the current output and the applied voltage can be mapped for an arbitrary gas concentration. By repeating this process at a number of gas concentration points, the relationship between the current output of the gas concentration sensor, the applied voltage, and the gas concentration can be mapped.
[0010]
In such a case, in order to create a correlation map by changing the combustion parameters of the combustion gas supply source and to create a desired gas concentration environment in the exhaust passage using the correlation map, an expensive model gas device is required unlike the related art. A desired three-dimensional characteristic can be obtained without using it.
[0011]
In the characteristic measuring method according to the second aspect, in the first aspect, the amount of fuel supplied to the engine is changed, and the gas concentration in the exhaust passage at that time is measured using a reference gas concentration meter. A correlation map between the fuel supply amount and the gas concentration in the exhaust passage is created (first procedure). Further, based on the created correlation map, the fuel supply amount is adjusted so that the inside of the exhaust passage has a predetermined gas concentration atmosphere, and in that state, the voltage applied to the gas concentration sensor is changed to change the current value flowing through the sensor. Is measured (second procedure).
[0012]
According to the second aspect, when the engine is a combustion gas supply source and the exhaust gas of the engine is combustion gas, the relationship between the current output of the gas concentration sensor, the applied voltage, and the gas concentration can be mapped. In such a case, since the characteristic measurement is performed by applying the existing engine system, desired three-dimensional characteristics can be obtained without using an expensive model gas device.
[0013]
In this case, the gas concentration sensor may be any sensor that detects the oxygen concentration (air-fuel ratio) in the exhaust gas using the limit current characteristics, or that detects NOx (nitrogen oxide).
[0014]
According to the first or second aspect of the present invention, as described in the third aspect, as a reference gas concentration meter, a current signal corresponding to the concentration of a specific component is provided in the exhaust passage as in the case of the gas concentration sensor and the voltage is applied. It is preferable to use a reference sensor for measuring a reference characteristic to be output.
[0015]
According to a fourth aspect of the present invention, there is provided the characteristic measuring method according to the second or third aspect, wherein the gas supply amount in the exhaust passage with respect to the fuel supply amount at a plurality of plot points while gradually increasing or decreasing the fuel supply amount to the engine. The concentration is measured, and the fuel supply amount is increased or decreased at least twice within a predetermined range (first procedure). According to the fourth aspect, for example, the fuel supply amount is changed from the minimum value to the maximum value, the change in gas concentration at that time is measured, and the cycle required for the change from the minimum value to the maximum value is repeated twice or more. If the measured values of the gas concentration are different even for the same fuel supply amount, the measured values may be averaged. As a result, a more reliable correlation map between the fuel supply amount and the gas concentration is obtained, and the characteristics of the gas concentration sensor can be accurately measured.
[0016]
According to a fifth aspect of the present invention, there is provided the characteristic measuring method according to any one of the second to fourth aspects, wherein the fuel supply amount and the gas supply amount are set at relatively small intervals near the maximum value and the minimum value of the fuel supply amount to the engine. The relationship between the fuel supply amount and the gas concentration is measured at relatively coarse intervals otherwise (first procedure).
[0017]
That is, for example, when measuring the air-fuel ratio with respect to the fuel supply amount, the relationship between the fuel supply amount and the air-fuel ratio has a linear increase / decrease relationship near the stoichiometric air-fuel ratio, whereas the relationship between the maximum value and the minimum value of the fuel supply amount is small. There is not always a linear relationship near the value (near the rich limit, near the lean limit) (see ranges A and B in FIG. 4). Accordingly, the fuel supply amount and the gas concentration are measured by measuring the relationship between the fuel supply amount and the gas concentration at small intervals only near the maximum value and the minimum value of the fuel supply amount to the engine. Is more accurate and reliable.
[0018]
In a state where the gas concentration sensor is mounted on an engine or the like, the gas concentration sensor is maintained at the activation temperature and operates properly. Therefore, a series of characteristic measurement procedures may be performed only in the activated state of the sensor so as to match the operation. Thereby, the reliability of the sensor characteristic measurement result is improved.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described below with reference to the drawings. In the present embodiment, a device and a method for measuring the output characteristics of an A / F sensor for detecting an air-fuel ratio (A / F) of exhaust gas discharged from a vehicle gasoline engine will be described in detail.
[0020]
FIG. 1 is a configuration diagram showing an entire apparatus for realizing characteristic measurement of an A / F sensor. In FIG. 1, an existing system is used as an engine system 10. The engine system 10 is roughly divided into an engine main body 11, an injector 12 for injecting fuel into each cylinder of the engine main body 11, and a fuel injection amount by the injector 12. An ECU (electronic control device) 13 is provided. As a general operation, the ECU 13 takes in a detection result of an A / F sensor 16 described later, and performs an air-fuel ratio feedback control so that the detection result matches a target air-fuel ratio.
[0021]
The ECU 13 is connected to an engine adaptation tool 14 as an external device. The engine adaptation tool 14 outputs a signal to change the fuel injection amount and the engine speed to the ECU 13, for example, to determine whether the map adaptation value in the ECU 13 is correct, or to adjust the amount of exhaust emission optimally. Or
[0022]
An exhaust pipe 15 connected to the engine body 11 is provided with an A / F sensor 16 of a limiting current type. The A / F sensor 16 detects the A / F from the oxygen concentration of the exhaust gas flowing through the exhaust pipe 15. To detect. Since the structure of the A / F sensor 16 is well known, its illustration and detailed description are omitted, but the configuration of the A / F sensor 16 will be briefly described below.
[0023]
In other words, the A / F sensor 16 has a solid electrolyte layer formed in a cup-shaped cross section and a diffusion resistance layer laminated outside the solid electrolyte layer, and the air electrode layer is fixed to the inner surface of the solid electrolyte layer. An exhaust gas side electrode layer is fixed to the outer surface. The solid electrolyte layer is made of an oxygen ion conductive oxide sintered body in which CaO, MgO, Y2O3, Yb2O3, etc. are dissolved as a stabilizer in ZrO2, HfO2, ThO2, Bi2O3, etc., and the diffusion resistance layer is It is made of a heat-resistant inorganic substance such as alumina, magnesia, quartzite, spinel, and mullite. Both the exhaust gas side electrode layer and the atmosphere side electrode layer are made of a noble metal having high catalytic activity such as platinum, and the surfaces thereof are subjected to porous chemical plating or the like.
[0024]
However, the A / F sensor 16 only needs to be capable of detecting the A / F linearly (linearly), and its structure is arbitrary, and may be a laminated structure other than the above-described cup-shaped structure. .
[0025]
The limit current characteristics of the A / F sensor 16 will be briefly described. As shown in the VI diagram of FIG. 2, the increase / decrease of the element limit current (current output I) corresponds to the increase / decrease of the air-fuel ratio. As the air-fuel ratio becomes leaner, the current output I increases and the air-fuel ratio becomes rich. , The current output I decreases. The voltage range smaller than the linear portion (limit current detection range) parallel to the V axis is the resistance dominating region, and the slope of the temporary linear portion in the resistance dominating region is determined by the DC element resistance of the solid electrolyte layer forming the sensor element portion. Is specified by The slope of the linear portion in the resistance dominant region changes according to the element temperature. For example, when the element temperature decreases, the element DC resistance increases and the slope decreases.
[0026]
Returning to FIG. 1, the sensor characteristic measuring device 17 is configured by an electric circuit having a well-known microcomputer (not shown), controls an applied voltage of the A / F sensor 16, and detects a sensor current flowing with the applied voltage. To detect. In the present embodiment, the sensor characteristic measuring device 17 serves as a central portion for evaluating the characteristics of the A / F sensor 16, and the characteristic measurement data is collected by the measuring device 17 and stored in an internal memory.
[0027]
A reference sensor 18 as a reference gas concentration meter is disposed in the exhaust pipe 15 so as to be adjacent to the A / F sensor 16. Like the A / F sensor 16, the reference sensor 18 is formed of a limiting current type air-fuel ratio sensor, and is calibrated in advance and exhibits a predetermined reference characteristic. A reference measuring device 19 is connected to the reference sensor 18, and controls the applied voltage of the reference sensor 18 and detects a sensor current flowing with the voltage application. The measurement result of the reference measuring device 19 is taken into the sensor characteristic measuring device 17 as needed.
[0028]
An exhaust gas temperature sensor 20 composed of a thermocouple or the like is disposed on the exhaust pipe 15 upstream of the A / F sensor 16 and the reference sensor 18, and a detection result of the exhaust gas temperature sensor 20 is a temperature indicator 21. Is output and displayed.
[0029]
Next, a procedure for measuring sensor characteristics will be described with reference to the flowchart in FIG. Here, the flowchart of FIG. 3 shows a processing procedure executed by the sensor characteristic measuring device 17, and this processing is executed in response to a request to perform sensor characteristic measurement. When performing this characteristic measurement, both the A / F sensor 16 and the reference sensor 18 need to be activated, and the exhaust gas temperature sensor 20 monitors the exhaust gas temperature. It is assumed that the active state of each of the sensors 16 and 18 is maintained by the exhaust gas, and the execution of the characteristic measurement is permitted.
[0030]
First, in step S1, a command is given to the engine adaptation tool 14 to change the fuel injection amount τ (the energizing time of the injector 12) from the minimum value to the maximum value, and the A / F of the exhaust gas at each time is measured by the reference sensor 18. Detect using Specifically, the sensor characteristic measuring device 17 gradually increases or decreases the fuel injection amount τ, and outputs the current output (A / F value) of the reference sensor 18 to the fuel injection amount τ at a plurality of plot points (for example, 300 points). Read. For the fuel injection amount τ, the change from the minimum value to the maximum value and the change from the maximum value to the minimum value are performed once each, and the average of the current output (A / F value) of the sensor in each of them is calculated. Further, at this time, in the vicinity of the maximum value and the minimum value of the fuel injection amount τ (ranges A and B in FIG. 4), the relationship between the τ value and the A / F value is changed by changing the fuel injection amount τ at relatively small intervals. Is measured, otherwise, the relationship between the τ value and the A / F value is measured at relatively coarse intervals.
[0031]
However, the fuel injection amount τ may be changed only once from the minimum value to the maximum value or from the maximum value to the minimum value. Further, the change ratio of the fuel injection amount τ may be always constant.
[0032]
In the following step S2, the detection result of the reference sensor 18 is fetched from the reference measurement device 19, and a correlation map (τ-A / F map) between the fuel injection amount τ and the A / F value is created. As shown in FIG. 4, the τ-A / F map has a substantially monotonically decreasing characteristic except for the ranges A and B.
[0033]
Then, in steps S3 to S7, the fuel injection amount τ is adjusted based on the τ-A / F map of FIG. 4 so that the inside of the exhaust pipe 15 has a desired A / F atmosphere. The value of the current flowing through the sensor 16 is measured by changing the voltage applied to the sensor 16. Here, the A / F detection range of the A / F sensor 16 is set to A / F = 12.0 to 20.0, and within the range, for example, A / F = 12.0, 14.7 (theoretical air-fuel ratio). , 16.0, 17.0, and 20.0, the current value of the A / F sensor 16 is measured.
[0034]
Specifically, in step S3, a command of the injection amount signal is given to the engine adaptation tool 14 so as to have a desired A / F value based on the τ-A / F map of FIG. For example, an injection signal of τ = 2700 μs is instructed so that the A / F value becomes 17.0. Further, in step S4, the A / F value at that time is measured by the reference sensor 18, and the process waits until the exhaust gas atmosphere in the exhaust pipe 15 is stabilized.
[0035]
In step S5, a voltage is applied to the A / F sensor 16 while sweeping in a predetermined range (for example, in the range of -0.2 to 0.9 V) in a state where the inside of the exhaust pipe 15 has a stable desired A / F atmosphere. Apply. Then, the value of the current flowing through the A / F sensor 16 with the application of the voltage is measured, and is sequentially stored in the memory. FIG. 5 shows the VI map obtained in step S5. By the process of step S5, the measurement cycle for one A / F point is completed.
[0036]
In the following step S6, it is determined whether or not the measurement of all the A / F points has been completed for a plurality of A / F points whose VI output characteristics are to be measured. If the measurement of the VI output characteristics has not been completed at all the A / F points, the process proceeds to step S7 to measure the output characteristics of the next A / F point, the A / F value is changed, and the data collection is continued. I do. That is, the process returns to step S3, and the injection amount signal command is again given to the engine adaptation tool 14 so as to obtain the changed A / F value, and a VI map is created for the A / F value at that time. Steps S3 to S7 are repeatedly executed until the measurement of the output characteristics of all A / F points is completed.
[0037]
Thereafter, if a positive determination is made in step S6, the process proceeds to step S8. In step S8, a three-dimensional output characteristic map is created by synthesizing the VI maps for each A / F stored in the memory in step S5, and then the present process ends. Thereby, as shown in FIG. 2, an output characteristic in which three parameters of the current output I, the applied voltage V, and the A / F are obtained is obtained. FIG. 2 does not show output characteristics at five points of A / F = 12.0, 14.7 (theoretical air-fuel ratio), 16.0, 17.0, and 20.0, but actually, A current value corresponding to five A / F points has a flat portion (limit current detection area).
[0038]
In the present embodiment, the engine body 11 corresponds to the “combustion gas supply source” of the present invention, and the fuel injection amount τ corresponds to the “combustion parameter”. Steps S1 and S2 in FIG. 3 correspond to the “first procedure” of the present invention, steps S3 to S5 correspond to the “second procedure”, steps S6 and S7 correspond to the “third procedure”, and step S8 corresponds to Each corresponds to a “fourth procedure”.
[0039]
According to the embodiment described in detail above, the following effects can be obtained.
(A) Since an A / F environment is arbitrarily created using the existing engine system 11 and the sensor characteristics are measured in that state, unlike the conventional technology, an expensive model gas device is not used, and the A / F is not used. Desired three-dimensional characteristics can be obtained for the relationship between the current output of the sensor 16, the applied voltage, and the A / F value. At the same time, the size of the apparatus can be suppressed.
[0040]
(B) When creating the τ-A / F map, the cycle of increasing or decreasing the fuel injection amount τ is repeated twice, so that a more reliable τ-A / F map is obtained, and as a result, the A / F sensor 16 characteristics can be measured accurately.
[0041]
(C) Similarly, when the τ-A / F map is created, the A / F value for the fuel injection amount τ is measured at small intervals only near the maximum value and the minimum value of the fuel injection amount τ. An accurate and reliable τ-A / F map is obtained. Further, by providing a region with a coarse measurement interval, the measurement time can be reduced.
[0042]
(D) Since the degree of activity of the A / F sensor 16 and the reference sensor 18 is determined and a series of characteristic measurement procedures are performed only in the sensor active state, the reliability of the sensor characteristic measurement result is improved.
[0043]
The present invention can be embodied in the following modes other than the above.
In the above embodiment, the A / F detection range of the A / F sensor 16 is set to A / F = 12.0 to 20.0, and within that range, for example, A / F = 12.0, 14.7 (theoretical Although the current value of the A / F sensor 16 was measured at five points of (air-fuel ratio), 16.0, 17.0, and 20.0, the change of the A / F detection range, the change of the A / F measurement point, etc. Of course, it is acceptable. If the A / F sensor whose characteristics have been measured according to the above series of procedures is used next as a reference sensor, it is preferable to measure characteristics at a relatively large number (10 to 20) of A / F points.
[0044]
In the above embodiment, the degree of activity of the A / F sensor 16 and the reference sensor 18 is determined by monitoring the exhaust gas temperature, but this is changed. For example, the element resistance of the reference sensor 18 is detected, and the degree of sensor activity is determined from the resistance value. If the sensors 16 and 18 are activated, the execution of the sensor characteristic measurement is permitted. Note that a heater may be provided for each of the sensors 16 and 18, and the amount of power supplied to the heater may be controlled so that the sensors 16 and 18 are always kept in the active state.
[0045]
In the above-described embodiment, the limit current type reference sensor 18 is used as the reference gas concentration meter similarly to the A / F sensor 16, but this is changed. Instead of using the reference sensor 18 equivalent to the A / F sensor 16, another reference gas concentration meter (calibrated) may be used.
[0046]
In the above embodiment, the A / F sensor is applied as the gas concentration sensor, but the present invention may be applied to a NOx sensor that detects the NOx concentration in exhaust gas. The NOx sensor, like the A / F sensor, detects the NOx concentration at the limit current, and may have any configuration such as a two-cell type or a three-cell type.
[0047]
When measuring the characteristics of the NOx sensor, a correlation map between the fuel injection amount of the engine and the NOx concentration is created in advance, and the inside of the exhaust pipe is set to a desired NOx concentration atmosphere based on the correlation map. The NOx concentration detection current flowing through the sensor is measured by changing the applied voltage. Further, the procedure is repeated while changing the NOx concentration atmosphere in the exhaust pipe, and the relationship between the applied voltage, the current output, and the NOx concentration of the NOx sensor is mapped based on the measured result.
[0048]
Further, the present invention may be applied to a gas concentration sensor for detecting the concentration of a specific component in a combustion gas supplied from another combustion gas supply source such as a combustion furnace or an incinerator, not limited to the exhaust gas of the engine.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing an entire apparatus for realizing characteristic measurement of an A / F sensor.
FIG. 2 is a VI diagram showing output characteristics of an A / F sensor.
FIG. 3 is a flowchart showing a procedure for measuring characteristics of an A / F sensor.
FIG. 4 is a diagram showing a τ-A / F map.
FIG. 5 is a VI diagram showing two-dimensional characteristics of the A / F sensor.
[Explanation of symbols]
Reference Signs List 10: engine system, 15: exhaust pipe, 16: A / F sensor, 17: sensor characteristic measuring device, 18: reference sensor, 19: reference measuring device, 20: exhaust gas temperature sensor

Claims (6)

A method for measuring a characteristic of a gas concentration sensor provided in an exhaust passage connected to a combustion gas supply source and outputting a current signal corresponding to a concentration of a specific component in the combustion gas in response to voltage application, ,
A first method of changing a combustion parameter in a combustion gas supply source, measuring a gas concentration in an exhaust passage at that time using a reference gas concentration meter, and creating a correlation map between the combustion parameter and the gas concentration in the exhaust passage. Instructions and
Thereafter, the combustion parameters are adjusted so that the inside of the exhaust passage has a predetermined gas concentration atmosphere based on the created correlation map, and in that state, the voltage applied to the gas concentration sensor is changed to change the current value flowing through the sensor. A second procedure for measuring;
A third procedure of repeating the second procedure while changing the gas concentration in the exhaust passage;
A fourth procedure for mapping the relationship between the applied voltage, the sensor current, and the gas concentration based on the results measured in the second and third procedures;
A characteristic measuring method for a gas concentration sensor, comprising: A method for measuring characteristics of a gas concentration sensor provided in an exhaust passage of an engine and detecting a concentration of a specific component in exhaust gas,
In the first procedure, the amount of fuel supplied to the engine is changed and the gas concentration in the exhaust passage at that time is measured using a reference gas concentration meter, and the correlation between the fuel supply amount and the gas concentration in the exhaust passage is measured. Create a map,
In the second procedure, the fuel supply amount is adjusted based on the created correlation map so that the inside of the exhaust passage has a predetermined gas concentration atmosphere, and in that state, the voltage applied to the gas concentration sensor is changed to change the fuel supply amount. The method for measuring characteristics of a gas concentration sensor according to claim 1, wherein a current value flowing through the sensor is measured. 3. The reference gas concentration meter according to claim 1, wherein a reference sensor for measuring reference characteristics is provided in an exhaust passage similarly to the gas concentration sensor, and outputs a current signal corresponding to a concentration of a specific component when voltage is applied. 4. The characteristic measuring method of the gas concentration sensor described in the above. The method for measuring characteristics of a gas concentration sensor according to claim 2 or 3,
In the first procedure, the gas concentration in the exhaust passage with respect to the fuel supply amount is measured at a plurality of plot points while gradually increasing or decreasing the fuel supply amount to the engine, and the increase or decrease in the fuel supply amount is determined by a predetermined value. A method for measuring characteristics of a gas concentration sensor performed at least twice in a range. In the characteristic measuring method of the gas concentration sensor according to any one of claims 2 to 4,
In the first procedure, the relationship between the fuel supply amount and the gas concentration is measured at relatively small intervals near the maximum value and the minimum value of the fuel supply amount to the engine. A method for measuring characteristics of a gas concentration sensor for measuring a relationship between an amount and a gas concentration. The method according to any one of claims 1 to 5, wherein the degree of activity of the gas concentration sensor is monitored, and a series of characteristic measurement procedures are performed only in a state where the sensor is activated.

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