Methods for accurately detecting signals, such as those from sensors.

Abstract

A method for accurately detecting a signal from, for example, a sensor (200), the detection being performed by means of, for example, an analysis processing and control unit (100) electrically connected to the sensor (100), wherein the analysis processing and control unit (100) has a multiplexer (110), at least a known voltage value (U) is applied at the input terminals (111, 112, 113, 114, 115, 116) of the multiplexer. Ref The reference voltage (U_R) of the exhaust gas sensor, the reference potential (GND_R) of the reference voltage, the measurement signal (U_M) of the exhaust gas sensor, and the reference potential (GND_M) of the measurement signal, wherein, via a transmission line (120) and via an ADC (130) that converts the voltage applied between its two input terminals (131, 132) into a digital value, a computing device (140) is connected after the multiplexer (110), wherein the method is set to perform a plurality of single measurements (E1, E2, E3, E4), in the single The method involves changing the switching state of the multiplexer (110) during the measurement, and subsequently detecting digital values ​​at the output of the ADC (130) in each single measurement. The method also involves the computing device (140) calculating the measured value after offset correction and gain correction from the digital values. The method is characterized by detecting the digital values ​​before the two levels at the input of the ADC (130) have reached a steady state, or starting the AD conversion before the two levels at the input of the ADC (130) have reached a steady state.

Description

Background Technology

[0001] A method known from the prior art involves transmitting an analog signal along a transmission path and subsequently digitizing it, wherein offset and gain errors that occur are corrected. This method always assumes that the transmitted signal to be digitized is time-constant (i.e., in a steady state) during digitization, thus enabling the easy acquisition of offset and gain error-free measurements from the analog signal, see, for example, US7,710,303B2. This method is correspondingly slow. Summary of the Invention

[0002] The present invention is based on the inventors’ unexpected discovery that the correct offset-corrected and gain-corrected measurements can also be determined in the method of the preamble of claim 1 without both levels at the input of the ADC (Analog-Digital-Wandler) reaching steady state in each single measurement.

[0003] Although each digital value obtained by a single measurement changes in particular compared to the value obtained after a transient process of waiting for the level applied to the input of the ADC, this change occurs in a substantially similar manner for all digital values, so that the changes at least partially compensate for each other when calculating the offset-corrected and gain-corrected measurements from the digital values.

[0004] Therefore, the present invention can accurately and simultaneously detect signals, such as those from sensors, very quickly. However, it can also be applied to any other signals.

[0005] Within the scope of this application, a system is considered to have reached a steady state only if its input parameters have changed, in particular, if its output parameters have undergone at least 86% of the change that would result from a static solution with the changed input parameters.

[0006] In one of its extended schemes, the system is considered to have reached a steady state after its input parameters have changed, especially when its output parameters have undergone at least 63% of the change that would result from a static solution with the changed input parameters.

[0007] This method can be configured to perform the following single measurement:

[0008] a) Reference voltage measurement: The multiplexer connects the reference voltage to the first input terminal of the ADC and the reference potential of the reference voltage to the second input terminal of the ADC; the reference voltage value is obtained at the output terminal of the ADC; and / or

[0009] b) Reference offset voltage measurement: The multiplexer connects the reference voltage to the two input terminals of the ADC; the reference offset voltage value is obtained at the output terminal of the ADC; and / or

[0010] c) Voltage Measurement: The multiplexer connects the measurement voltage to the first input terminal of the ADC and the reference potential of the measurement voltage to the second input terminal of the ADC; the measurement voltage value is obtained at the output terminal of the ADC; and / or

[0011] d) Measurement of offset voltage: The multiplexer connects the reference potential of the measurement voltage to the two input terminals of the ADC; the measurement offset voltage value is obtained at the output terminal of the ADC.

[0012] If the reference potential of the reference voltage and the reference potential of the measured voltage are physically the same, then a) and d) can be achieved simultaneously by a single measurement, the result of which provides both the reference offset voltage value and the measured offset voltage value.

[0013] The offset-corrected and gain-corrected measurements can then be calculated using the following formula:

[0014] U_MuC=U Ref *(Z_UM-Z_UMoffset) / (Z_UR-Z_URoffset),

[0015] in,

[0016] U_MuC is a measurement that has been adjusted for offset and gain.

[0017] U Ref It is the known voltage value of the reference voltage;

[0018] Z_UM is the measured voltage value;

[0019] Z_UMoffset is the measured offset voltage value;

[0020] Z_UR is the reference voltage value;

[0021] ZURoffset is the reference offset voltage value.

[0022] The effect upon which this invention is based, namely that the aforementioned changes at least partially compensate for each other in the measured values ​​calculated from digital values ​​after offset and gain correction, is given to a particularly high degree when the analysis processing and control unit are placed in the same basic state before each individual measurement. For this purpose, it can be configured that, before each individual measurement, individual or all of the energy memories, function values, digital memories, and / or function blocks of the analysis processing and control unit are reset to the same, defined, but not necessarily static, basic state.

[0023] The effect upon which this invention is based, namely that the aforementioned variations at least partially compensate for each other in the measured values ​​calculated from digital values ​​after offset and gain correction, is also given to a particularly high degree when: individual measurements have the same timing relative to each other, i.e., in particular, other measurements of the same or similar nature are always performed at the same time intervals by means of analysis processing and control unit immediately preceding the measurement; and / or the switches of the multiplexer have accurate matching relative to each other, i.e., in particular, the switches have the same resistance value in the off state, the switches have the same resistance value in the on state, and / or the switching times of the switches are the same. The concept of similarity here includes only a fairly narrow range of fluctuation, for example, ±2%.

[0024] In order for the sensor to operate in accordance with the destination settings, individual measurements and the calculation of measurements after offset correction and gain correction are repeated periodically.

[0025] The sensor may involve a lambda detector, such as a broadband lambda detector. The signal from the lambda detector may, for example, involve a voltage that can be measured between its feed lines. The analysis, processing, and control unit can be implemented using an ASIC. Attached Figure Description

[0026] Figure 1 An exemplary circuit is shown, by means of which the method according to the invention can be performed.

[0027] Figure 2 The method according to the invention is illustrated by way of flowcharts. Detailed Implementation

[0028] Figure 1 An analysis processing and control unit 100 for operating the broadband λ detector 200 is shown. The analysis processing and control unit 100 is connected via a connection terminal (in... Figure 1 Only two connection terminals (A1, A2) are shown connected to wires 201, 202 of the broadband λ detector 200. These lines 201, 202 lead, for example, to the electrochemical cell 210 of the broadband λ detector 200, thus providing the measurement voltage UM and its reference potential GND_M of the broadband λ detector 200. The analysis processing and control unit 100 is connected to the reference voltage source 300 and its reference potential GND_R via two additional connection terminals (A3, A4). Alternatively, the reference voltage source 300 and its reference potential GND_R may also be part of the analysis processing and control unit 100. The actual value U of the voltage provided by the reference voltage source 300... Ref It is known very precisely and is also constant over time.

[0029] Possible details of the broadband λ detector 200 are shown, for example, in DE 10 2011 007 068 A1.

[0030] The analysis processing and control unit 100 is shown only to the extent necessary for understanding the invention. Possible details of the analysis processing and control unit 100 are shown, for example, in patent document EP 2 277 035 B1.

[0031] exist Figure 1 The multiplexer 110 shown in the example has six input terminals 111, 112, 113, 114, 115, and 116. The first input terminal 111 is connected to a reference voltage U_R, the second and fifth input terminals 112 and 115 are connected to a reference potential GND_R of the reference voltage, the third input terminal 113 is connected to a measured voltage U_M, and the fourth and sixth input terminals 114 and 116 are connected to the reference potential GND_M of the measured voltage.

[0032] The first, second, third, and fourth inputs 111, 112, 113, and 114 of the multiplexer 110 can be connected to the first output 118 of the multiplexer 110 via the first switch P1 associated with the first input terminal 111 of the multiplexer 110 and via the other switches P2, P3, P4, M1, and M2 associated with the other input terminals 112, 113, 114, 115, and 116 of the multiplexer 110, and the fifth and sixth input terminals 115 and 116 of the multiplexer 110 can be connected to the second output 119 of the multiplexer 110. The switches P1, P2, P3, P4, M1, and M2 of the multiplexer 110 are precisely matched to each other, that is, the internal resistance of the switch in the open state, the internal resistance of the switch in the closed state, and / or the switching time of the switch are only slightly different, for example, not more than 2%.

[0033] The inputs 131, 132 of an analog-to-digital converter 130 are connected after the two outputs 118, 119 of a multiplexer 110 via a transmission path 120 having, for example, one or more filters and one or more amplifiers and additional functional blocks if necessary, and exhibiting low-pass behavior in general. The analog-to-digital converter converts the voltage applied between its two inputs 131, 132 into a digital value and forwards the digital value to a digital computing device 140.

[0034] The method according to the invention, for example, in steps S1 to S13 (see...) Figure 2The steps are defined in time, for example, by a clock T applied externally to the analysis and control unit or generated by the analysis and control unit itself.

[0035] Step S1: Reset all function blocks, energy storage, and digital storage to their defined basic states.

[0036] Step S2: Connect the input terminals 131 and 132 of ADC 130 to the reference voltage U_R and its reference potential GND_R. To do this, turn off the first switch P1 and the fifth switch M1.

[0037] Step S3: Detect the reference voltage value Z_UR on the output terminal 133 of ADC 130, more precisely, before the two levels on the input terminals 131 and 132 of ADC 130 have reached a steady state. Submit the reference voltage value Z_UR to the digital computing device 140.

[0038] Step S4: Reset all functional blocks, energy storage and digital storage to the basic state as defined in step 1.

[0039] Step S5: Connect the two input terminals 131 and 132 of ADC 130 to the reference potential GND_R of the reference voltage. To do this, turn off the second switch P2 and the fifth switch M1.

[0040] Step S6: Detect the reference offset voltage value Z_URoffset on the output terminal 133 of ADC 130, more precisely, before the two levels on the input terminals 131 and 132 of ADC 130 have reached a steady state. Submit the reference offset voltage value Z_URoffset to the digital computing device 140.

[0041] Step S7: Reset all functional blocks, energy storage and digital storage to the basic state as defined in step 1 and step 4.

[0042] Step S8: Connect the input terminals 131 and 132 of ADC 130 to the measured voltage U_M and its reference potential GND_M. To do this, turn off the third switch P3 and the sixth switch M2.

[0043] Step S9: Detect the measured voltage value Z_UM at the output terminal 133 of ADC 130, more precisely, before the two levels at the input terminals 131 and 132 of ADC 130 have reached a steady state. Submit the measured voltage value Z_UM to the digital computing device 140.

[0044] Step S10: Reset all functional blocks, energy storage and digital storage to the basic state as defined in steps 1, 4 and 7.

[0045] Step S11: Connect the two input terminals 131 and 132 of ADC 130 to the reference potential GND_M for measuring the voltage. To do this, turn off the fourth switch P4 and the sixth switch M2.

[0046] Step S12: Detect the measured offset voltage value Z_UMoffset on the output terminal 133 of ADC 130, more precisely, before the two levels on the input terminals 131 and 132 of ADC 130 have reached a steady state. Submit the measured offset voltage value Z_UMoffset to the digital computing device 140.

[0047] Step S13: Based on the following formula, using the previously obtained digital values ​​Z_UM, Z_UMoffset, Z_UR, and Z_Uroffset, and the known value U of the reference voltage... Ref The measured value U_MuC after offset correction and gain correction is calculated:

[0048] U_MuC=U Ref *(Z_UM-Z_UMoffset) / (Z_UR-Z_URoffset).

[0049] The offset-corrected and gain-corrected measurement value U_MuC obtained in this way can continue to be used technically. For example, this measurement value can be stored non-volatilely in the analysis processing and control unit 100 and / or submitted as the actual value of the voltage applied to the electrochemical cell 210 to the regulator of the analysis processing and control unit 100, which, in turn, physically manipulates the broadband λ detector 200 by the corresponding voltage and current.

[0050] The measurement of the reference voltage value Z_UR (E1; method steps S1, S2, S3) and the measurement of the reference offset voltage value Z_URoffset (E2; method steps S4, S5, S6) are performed close in time, thereby eliminating the main physical changes in the analysis, processing and control unit 100 caused by temperature and / or aging during this period.

[0051] The measurement of the reference voltage value Z_UR (E1; method steps S1, S2, S3) is performed at the same timing as the measurement of the reference offset voltage value Z_URoffset (method steps E2; S4, S5, S6), so that for both measurements, similar dynamic effects are produced due to not waiting for transient oscillations of the levels at the input terminals 131, 132 of the ADC.

[0052] Apart from their specific differences, the two single measurements E1 and E2 are performed in the same system state of the analysis, processing and control unit 100. For example, between the single measurements E1 and E2, the connection of additional current and voltage is omitted, as long as it may affect the measurement.

[0053] The measurement of voltage value Z_UM (E3, method steps S7, S8, S9) and the measurement of offset voltage value Z_UMoffset (E4, method steps S4, S5, S6) are performed in close proximity in time, thereby eliminating the main physical changes in the analysis, processing and control unit 100 caused by temperature and / or aging during this period.

[0054] The measurement of voltage value Z_UM (E3; method steps S10, S11, S12) is performed at the same timing as the measurement of offset voltage value Z_UMoffset (E4; method steps S4, S5, S6), so that for both measurements, a similar dynamic effect is produced due to not waiting for transient oscillations of the levels at the input terminals 131, 132 of the ADC.

[0055] Apart from their specific differences, the two single measurements E3 and E4 are performed in the same system state of the analysis, processing and control unit 100. For example, between the single measurements E3 and E4, additional current and voltage switching is omitted, as long as it may affect the measurement.

[0056] Under the current circumstances, even all individual measurements E1, E2, E3, and E4, apart from their specific differences, are performed at the same timing and close to each other in time under the same system state of the analysis, processing, and control unit 100.

[0057] The present invention also utilizes the following technical advantages in this example: the transfer function of the measurement path, consisting of multiplexer 110, transmission path 120, and ADC 130, is the same in all single measurements E1, E2, E3, and E4. Therefore, the measurement error in the measured voltage value is proportionally the same as the measurement error in the measured reference voltage value. Thus, when calculating the offset-corrected and gain-corrected measured value U_MuC, these errors largely compensate for each other.

Claims

1. A method for accurately detecting a signal from a sensor (200), said detection being performed by means of an analysis, processing, and control unit (100) electrically connected to said sensor (200), wherein, The analysis, processing, and control unit (100) has a multiplexer (110) to which at least a reference voltage (U_R) of known voltage value, a reference potential (GND_R) of the reference voltage, a measurement signal from the sensor, and a reference potential of the measurement signal are applied, at least at the inputs (111, 112, 113, 114, 115, 116) of the multiplexer, wherein a computing device (140) is connected after the multiplexer (110) via a transmission line (120) and via an ADC (130) that converts the voltage applied between its two inputs (131, 132) into a digital value, wherein the method is configured to perform a plurality of single measurements (E1, E2, E3, E4), in which multiple values ​​are changed respectively. The method involves detecting the switching state of the multiplexer (110) and subsequently detecting digital values ​​at the output of the ADC (130) in the single measurement, wherein the computing device (140) calculates the measured value after offset correction and gain correction from the digital value, characterized in that the digital value is detected before at least 86% of the change caused by the static solution with the changed switching state has been completed for the two levels at the input of the ADC (130), or AD conversion is started before at least 86% of the change caused by the static solution with the changed switching state has been completed for the two levels at the input of the ADC (130), and performing the following single measurements (E1, E2, E3, E4): a) Reference voltage measurement (E1): The multiplexer (110) connects the reference voltage (U_R) to the first input terminal (131) of the ADC (130) and connects the reference potential (GND_R) of the reference voltage to the second input terminal (132) of the ADC (130); the reference voltage value is obtained at the output terminal (133) of the ADC (130). b) Reference offset voltage measurement (E2): The multiplexer (110) connects the reference potential (GND_R) of the reference voltage to the two input terminals (131, 132) of the ADC (130); the reference offset voltage value is obtained at the output terminal (133) of the ADC (130). c) Voltage Measurement (E3): The multiplexer (110) connects the measured voltage to the first input terminal (131) of the ADC (130) and connects the reference potential (GND_M) of the measured voltage to the second input terminal (132) of the ADC (130); the measured voltage value is obtained at the output terminal (133) of the ADC (130). d) Measurement of voltage offset voltage (E4): The multiplexer (110) connects the reference potential (GND_M) of the measurement voltage to the two input terminals (131, 132) of the ADC (130); the measurement offset voltage value is obtained at the output terminal of the ADC (130); The offset-corrected and gain-corrected measurements are calculated according to the following formula: U_MuC=U Ref *(Z_UM-Z_UMoffset) / (Z_UR-Z_URoffset), in, U_MuC is the measured value after offset correction and gain correction; U Ref The reference voltage (U) Ref The known voltage value; Z_UM is the measured voltage value; Z_UMoffset is the measured offset voltage value; Z_UR is the reference voltage value; Z_URoffset is the reference offset voltage value.

2. The method according to claim 1, characterized in that, The single measurement (E1, E2, E3, E4) and the calculation of the offset-corrected and gain-corrected measurement values ​​are repeated periodically.

3. The method according to claim 1 or 2, characterized in that, The sensor (200) is a broadband λ detector, and the analysis, processing and control unit (100) is configured as an ASIC.

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