阅读说明：本技术 用于精准检测例如传感器的信号的方法 (Method for the precise detection of signals, for example of sensors ) 是由 C·贝沃特 B·莱德曼 F·梅茨格尔 F·鲍曼 于 2020-04-07 设计创作，主要内容包括：一种用于精准检测例如传感器(200)的信号的方法,所述检测借助例如与所述传感器(100)电连接的分析处理和控制单元(100)进行,其中,所述分析处理和控制单元(100)具有多路复用器(110),在所述多路复用器的输入端(111,112,113,114,115,116)处至少施加已知其电压值(U-(Ref))的参考电压(U-R)、所述参考电压的参考电位(GND-R)、废气传感器的测量信号(U-M)和所述测量信号的参考电位(GND-M),其中,经由传输路线(120)并经由将在其两个输入端(131、132)之间施加的电压转换为数字值的ADC(130),在所述多路复用器(110)的后面连接计算装置(140),其中,所述方法设置,执行多个单次测量(E1,E2,E3,E4),在所述单次测量中分别改变所述多路复用器(110)的开关状态,并且在所述单次测量中分别随后在所述ADC(130)的输出端处检测数字值,并且所述方法设置,所述计算装置(140)由所述数字值计算经偏移校正和增益校正的测量值,其特征在于,在所述ADC(130)的输入端处的两个电平已经达到稳态之前分别检测所述数字值,或者在所述ADC(130)的输入端处的两个电平已经达到稳态之前开始所述AD转换。(Method for the precise detection of signals, for example of a sensor (200), by means of an evaluation and control unit (100), for example electrically connected to the sensor (100), wherein the evaluation and control unit (100) has a multiplexer (110), at the input (111, 112, 113, 114, 115, 116) of which at least one known voltage value (U) is applied Ref ) Via a transmission line (120) and via a reference potential (GND _ M) which converts a voltage applied between its two inputs (131, 132) into a digital valueAn ADC (130) connected downstream of the multiplexer (110) to a computing device (140), wherein the method provides that a plurality of single measurements (E1, E2, E3, E4) are carried out in which the switching state of the multiplexer (110) is changed in each case and in which a digital value is subsequently detected at the output of the ADC (130) in each case, and that the computing device (140) computes an offset-corrected and gain-corrected measurement value from the digital values, characterized in that the digital values are detected in each case before the two levels at the input of the ADC (130) have reached a steady state or the AD conversion is started before the two levels at the input of the ADC (130) have reached a steady state.)

1. Method for the precise detection of signals, for example of a sensor (200), by means of an evaluation and control unit (100), for example electrically connected to the sensor (100), wherein the evaluation and control unit (100) has a multiplexer (110), at the input (111, 112, 113, 114, 115, 116) of which at least one known voltage value (U) is applied_Ref) A reference voltage (U _ R), a reference potential (GND _ R) of said reference voltage) A measurement signal (U _ M) of an exhaust gas sensor and a reference potential (GND _ M) of the measurement signal, wherein, via a transmission line (120) and via an ADC (130) which converts a voltage applied between its two inputs (131, 132) into a digital value, a computing device (140) is connected downstream of the multiplexer (110), wherein the method provides that a plurality of single measurements (E1, E2, E3, E4) are carried out, in each case the switching state of the multiplexer (110) is changed in the single measurement, and in each case a digital value is subsequently detected at the output of the ADC (130), and that the computing device (140) calculates from the digital values an offset-corrected and gain-corrected measurement value, characterized in that the digital values are detected in each case before the two levels at the input of the ADC (130) have reached a steady state, or the AD conversion is started before both levels at the input of the ADC (130) have reached a steady state.

2. The method according to claim 1, characterized in that the following single measurements (E1, E2, E3, E4) are performed:

a) reference voltage measurement (E1): -the multiplexer (110) switches the reference voltage (U _ R) on to a first input (131) of the ADC (130) and a reference potential (GND _ R) of the reference voltage on to a second input (132) of the ADC (130); -evaluating a reference voltage value (Z _ UR) at an output (133) of the ADC (130),

b) reference offset voltage measurement (E2): the multiplexer (110) switches a reference potential (GND _ R) of the reference voltage to two inputs (131, 132) of the ADC (130); -deriving a reference offset voltage value (Z _ URoffset) at an output (133) of the ADC (130),

c) measurement voltage measurement (E3): -the multiplexer (110) switches the measurement voltage (U _ M) to a first input (131) of the ADC (130) and a reference potential (GND _ M) of the measurement voltage to a second input (132) of the ADC (130); -evaluating a measurement voltage value (Z _ UM) at an output (133) of the ADC (130),

d) measuring voltage offset voltage measurement (E4): the multiplexer (110) switches the reference potential (GND _ M) of the measurement voltage to two inputs (131, 132) of the ADC (130); -evaluating a measured offset voltage value (Z UMoffset) at an output of the ADC (130);

and calculating the offset corrected and gain corrected measurement (U _ MuC) according to the following formula:

U_MuC＝U_Ref*(Z_UM-Z_UMoffset)/(Z_UR-Z_URoffset)，

wherein the content of the first and second substances,

u _ MuC is the offset corrected and gain corrected measurement (U _ MuC);

U_Refis the reference voltage (U)_Ref) A known voltage value of;

z _ UM is the measured voltage value (Z _ UM);

z _ UMoffset is the measured offset voltage value (Z _ UMoffset);

z _ UR is a reference voltage value (Z _ UR);

z _ ureffset is the reference offset voltage value (Z _ ureffset).

3. The method according to any one of the preceding claims, characterized in that the analytical processing and control unit (100) is placed in the same basic state before each single measurement (E1, E2, E3, E4).

4. The method according to any of the preceding claims, characterized in that the single measurements (E1, E2, E3, E4) have the same timing with respect to each other.

5. Method according to any of the preceding claims, characterized in that the switches (P1, P2, P3, P4, M1, M2) of the multiplexer (110) have an exact match with each other.

6. The method according to any of the preceding claims, characterized in that the calculation of the single measurement (E1, E2, E3, E4) and the offset-corrected and gain-corrected measurement value (U _ MuC) is repeated periodically.

7. Method according to any one of the preceding claims, characterized in that the sensor (200) is a broadband lambda probe and the analysis processing and control unit (100) is configured as an ASIC.

Background

The following methods are known from the prior art: by means of the method, an analog signal is transmitted along a transmission line and is subsequently digitized, wherein offset errors and gain errors occurring in the transmission line are corrected. In the method, it is always assumed that the transmitted signal to be digitized is constant in time during the digitization (i.e. is in a steady-state (eingeschwungen)) so that measured values without offset and gain errors can be easily obtained from the analog signal, see for example US 7,710,303B 2. The method is correspondingly slow.

Disclosure of Invention

The present invention is based on the following unexpected findings of the inventors: in the method according to the preamble of claim 1, it is also possible to determine the correct offset-corrected and gain-corrected measurement values without both levels at the input of the ADC (Analog-Digital-wander, english) having reached a steady state in each single measurement.

Although each of the digital values obtained by a single measurement changes in particular compared to the value that would be obtained after a transient process (Einschwingvorgangs) waiting for the level applied at the input of the ADC, such a change occurs in a substantially similar manner for all digital values, so that the changes compensate each other at least partially when offset-corrected and gain-corrected measurement values are calculated from the digital values.

The invention thus enables a precise and at the same time particularly rapid detection of signals, for example of sensors. But any other signal may be involved.

Within the scope of the present application, a system is considered to reach a steady state after a change in its input variables, in particular only if: its output variable has completed at least 86% of the variation for which it was caused according to the static solution with the changed input variable.

In one embodiment, the system is already considered to reach steady state after a change in its input variables, in particular when: its output variable has completed at least 63% of the change for which it was caused according to the static solution with the changed input variable.

The method may be arranged to perform the following single measurement:

a) and (3) reference voltage measurement: the multiplexer connects the reference voltage to a first input terminal of the ADC and connects the reference potential of the reference voltage to a second input terminal of the ADC; calculating a reference voltage value at an output of the ADC; and/or

b) Reference offset voltage measurement: the multiplexer switches on the reference potential of the reference voltage to two input ends of the ADC; calculating a reference offset voltage value at an output of the ADC; and/or

c) Measuring voltage measurement: the multiplexer connects the measurement voltage to a first input terminal of the ADC and connects a reference potential of the measurement voltage to a second input terminal of the ADC; calculating a measurement voltage value at an output of the ADC; and/or

d) Measuring offset voltage measurement: the multiplexer connects the reference potential of the measuring voltage to two input ends of the ADC; a measured offset voltage value is evaluated at the output of the ADC.

If the reference potential of the reference is physically the same as the reference potential of the measurement voltage, the single measurements a) and d) can be carried out simultaneously by a single measurement, the result of which provides both the reference offset voltage value and the measurement offset voltage value.

The offset-corrected and gain-corrected measured values can then be calculated, inter alia, according to the following formula:

U_MuC＝U_Ref*(Z_UM-Z_UMoffset)/(Z_UR-Z_URoffset)，

wherein the content of the first and second substances,

u _ MuC is the offset corrected and gain corrected measurement;

U_Refis a known voltage value of the reference voltage;

z _ UM is a measured voltage value;

z _ UMoffset is the measured offset voltage value;

z _ UR is a reference voltage value;

ZURoffset is the reference offset voltage value.

The effect on which the invention is based, that is to say the above-mentioned changes compensate each other at least partially in the calculation of the offset-corrected and gain-corrected measured values from the digital values, is given to a particularly high degree in the following cases: the analytical processing and control unit is put in the same basic state before each single measurement. For this purpose, it can be provided that prior to each individual measurement, individual or all energy stores, function values, digital memories and/or function blocks of the evaluation and control unit are reset to the same, defined, but not necessarily static, basic state.

The effect on which the invention is based, that is to say the above-mentioned changes compensate at least partially one another in the calculation of the offset-corrected and gain-corrected measured values from the digital values, is also given to a particularly high degree in the following cases: the individual measurements have the same timing with respect to one another, i.e. in particular immediately before the measurement, the same or similar further measurements are always carried out at the same time intervals by means of the evaluation and control unit; and/or the switches of the multiplexer have an exact match with respect to one another, i.e. in particular the switches have the same resistance value in the closed state, the switches have the same resistance value in the open state and/or the switching times of the switches are the same. The concept of identity here includes only a rather narrow fluctuation range, for example plus/minus 2%.

In order to operate the sensor in accordance with the intended setting, the individual measurements and the calculation of the offset-corrected and gain-corrected measured values are repeated periodically.

The sensor may relate to a lambda probe (Lambdasonde), for example to a broadband lambda probe. The signal of the lambda probe can, for example, relate to a voltage which can be tapped between its feed lines. The analysis processing and control unit may be implemented by an ASIC.

Drawings

Fig. 1 shows an exemplary circuit, with the aid of which a method according to the invention can be carried out.

Fig. 2 shows an exemplary method according to the invention in a flow chart.

Detailed Description

Fig. 1 shows an evaluation and control unit 100 for operating a broadband lambda probe 200. The evaluation and control unit 100 is connected to the lines 201, 202 of the broadband lambda probe 200 via connections (only two of which are shown in fig. 1 as connections a1, a 2). The lines 201, 202 lead, for example, to the electrochemical cell 210 of the broadband lambda probe 200, so that the measurement voltage UM of the broadband lambda probe 200 and its reference potential GND _ M are present on the lines. The evaluation and control unit 100 is connected via two further connections A3, a4 to the reference voltage source 300 and its reference potential GND _ R. Alternatively, the reference voltage source 300 and its reference potential GND _ R can also be part of the evaluation and control unit 100. The actual value U of the voltage supplied by the reference voltage source 300_RefAre very accurately known and are furthermore constant in time.

Possible details of the broadband lambda probe 200 are shown, for example, in DE 102011007068 a 1.

The evaluation and control unit 100 is only shown to the extent that it is necessary for the understanding of the invention. Possible details of the analysis processing and control unit 100 are shown, for example, in patent document EP 2277035B 1.

The multiplexer 110 shown by way of example in fig. 1 has six inputs 111, 112, 113, 114, 115, 116, of which a first input 111 is connected to a reference voltage U _ R, second and fifth inputs 112, 115 are connected to a reference potential GND _ R of the reference voltage, a third input 113 is connected to a measurement voltage U _ M, and fourth and sixth inputs 114, 116 are connected to a reference potential GND _ M of the measurement voltage.

Via the first switch P1 of the multiplexer 110 assigned to the first input 111 of the multiplexer 110 and via the further switches P2, P3, P4, M1, M2 of the multiplexer 110 assigned to the further inputs 112, 113, 114, 115, 116 of the multiplexer 110, the first, second, third and fourth inputs 111, 112, 113, 114 of the multiplexer 110 can be connected to the first output 118 of the multiplexer 110 and the fifth and sixth inputs 115, 116 of the multiplexer 110 can be connected to the second output 119 of the multiplexer 110. The switches P1, P2, P3, P4, M1, M2 of the multiplexer 110 have an exact match with one another, i.e. the internal resistances of the switches in the open state, the internal resistances of the switches in the closed state and/or the switching times of the switches differ only slightly, for example not more than 2%.

Via a transmission line 120, which has, for example, one or more filters and one or more amplifiers and, if appropriate, further functional blocks and, for example, exhibits overall low-pass behavior, the two outputs 118, 119 of the multiplexer 110 are followed by inputs 131, 132 of an analog-to-digital converter 130, which converts the voltage applied between its two inputs 131, 132 into a digital value and forwards said digital value to a digital computation device 140.

The method according to the invention is executed, for example, in steps S1 to S13 (see fig. 2), which are defined in time, for example, by a clock T applied externally to the evaluation and control unit or generated by the evaluation and control unit itself:

step S1: all functional blocks, energy stores and digital memories are reset to a defined basic state.

Step S2: the inputs 131, 132 of the ADC 130 are connected to the reference voltage U _ R and its reference potential GND _ R. For this purpose, the first switch P1 and the fifth switch M1 are closed.

Step S3: the reference voltage value Z _ UR at the output 133 of the ADC 130 is detected, to be precise, already in time before the two levels at the inputs 131, 132 of the ADC 130 have reached the steady state. The reference voltage value Z _ UR is delivered to the digital calculation device 140.

Step S4: all functional blocks, energy stores and digital stores are reset to the basic state as defined in step 1.

Step S5: the two inputs 131, 132 of the ADC 130 are connected to the reference potential GND _ R of the reference voltage. For this purpose, the second switch P2 and the fifth switch M1 are closed.

Step S6: the reference offset voltage value Z _ ureoffset at the output 133 of the ADC 130 is detected, that is to say, already in time before the two levels at the inputs 131, 132 of the ADC 130 have reached the steady state. The reference offset voltage value Z _ ureoffset is delivered to the digital computing device 140.

Step S7: all functional blocks, energy stores and digital stores are reset to the basic state as defined in step 1 and in step 4.

Step S8: the inputs 131, 132 of the ADC 130 are connected to the measurement voltage U _ M and its reference potential GND _ M. For this purpose, the third switch P3 and the sixth switch M2 are closed.

Step S9: the measurement voltage value Z _ UM at the output 133 of the ADC 130 is detected, to be precise, already in time before the two levels at the inputs 131, 132 of the ADC 130 have reached the steady state. The measured voltage value Z _ UM is delivered to the digital calculation means 140.

Step S10: all functional blocks, energy stores and digital stores are reset to the basic state as defined in steps 1, 4 and 7.

Step S11: the two inputs 131, 132 of the ADC 130 are connected to the reference potential GND _ M of the measurement voltage. For this reason, the fourth switch P4 and the sixth switch M2 are closed.

Step S12: the measured offset voltage value Z _ UMoffset at the output 133 of the ADC 130 is detected, more precisely, already in time before the two levels at the inputs 131, 132 of the ADC 130 have reached a steady state. The measured offset voltage value Z _ Umoffset is submitted to the digital calculation means 140.

Step S13: from the digital values Z _ UM, Z _ UMoffset, Z _ UR and Z _ unroffset obtained in advance and the known value U of the reference voltage according to the following formula_RefCalculating the offset corrected and gain corrected measurement value U _ MuC:

U_MuC＝U_Ref*(Z_UM-Z_UMoffset)/(Z_UR-Z_URoffset)。

the offset-corrected and gain-corrected measured value U _ MuC thus obtained can be used continuously in technology. For example, the measured values can be stored in the evaluation and control unit 100 in a non-volatile manner and/or can be delivered as actual values of the voltage applied to the electrochemical cell 210 to a controller of the evaluation and control unit 100, which in turn physically actuates the broadband lambda probe 200 by means of corresponding voltages and currents.

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 _ ureoffset (E2; method steps S4, S5, S6) take place in temporal proximity, so that major physical changes of the evaluation and control unit 100 due to temperature and/or aging are excluded during this time.

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 _ ureoffset (method steps E2; S4, S5, S6), so that for both measurements a similar dynamic effect is produced due to the transient oscillation of the level on the input 131, 132 of the ADC not being awaited.

Apart from their specific differences, the two single measurements E1, E2 are carried out under the same system conditions of the analytical processing and control unit 100, for example, between the single measurements E1, E2, the switching-on of further currents and voltages (alternan) is omitted, as long as it may affect the measurement.

The measurement of the measured voltage value Z _ UM (E3, method steps S7, S8, S9) and the measurement of the measured offset voltage value Z _ UMoffset (E4, method steps S4, S5, S6) take place temporally close to one another, so that major physical changes of the evaluation and control unit 100 due to temperature and/or aging are excluded during this time.

The measurement of the measurement voltage value Z _ UM (E3; method steps S10, S11, S12) takes place at the same timing as the measurement of the measurement offset voltage value Z _ UMoffset (E4; method steps S4, S5, S6), so that a similar dynamic effect is produced for both measurements due to the fact that transient oscillations of the level on the input 131, 132 of the ADC are not awaited.

Apart from their specific differences, the two single measurements E3, E4 are carried out under the same system conditions of the analytical processing and control unit 100, for example between said single measurements E3, E4, the switching-on of further currents and voltages being omitted, as long as it may affect the measurement.

In the present case, even all the single measurements E1, E2, E3 and E4, apart from their specific differences, proceed at the same timing and close in time to one another in the same system state of the analytical processing and control unit 100.

The invention also takes advantage of the following technical advantages in the examples: the transfer function of the measurement path consisting of the multiplexer 110, the transmission line 120 and the ADC 130 is the same in all single measurements E1, E2, E3, E4, and therefore the error in the measurement of the measured voltage value is proportionally the same as the measurement error in the measurement of the reference voltage value. Therefore, when the offset-corrected and gain-corrected measurement values U _ MuC are calculated, the errors largely compensate for each other.