CN114264225A - Real-time fault discrimination circuit and method for potentiometer type corner sensor - Google Patents
Real-time fault discrimination circuit and method for potentiometer type corner sensor Download PDFInfo
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Abstract
The invention provides a real-time fault discrimination circuit and a discrimination method for a potentiometer type corner sensor, which comprises a potentiometer VR, a bias resistor Rtest and a singlechip U, wherein the singlechip U comprises an analog-to-digital converter ADC and an IO port end with push-pull output and high-resistance input functions; the upper end of the potentiometer VR is connected with a positive terminal X of a reference voltage Vref, the lower end of the potentiometer VR is connected with a reference ground D, and an electric brush is connected with a positive terminal of an output voltage Vx; one end of a bias resistor Rtest is connected to the end of a potentiometer VR brush, and the other end of the bias resistor Rtest is connected to a node A; the power supply voltage VCC end of the singlechip U is connected with the positive terminal X of the reference voltage Vref, the input analog quantity Adin is connected with the electric brush of the potentiometer VR, and the IO port is connected with the node A. The invention can judge the contact resistance of the potentiometer in each measuring period, judge whether the potentiometer has faults or not, immediately find out the faults after sudden failure and process the faults, and avoid serious consequences caused by using wrong measured values. The operation and judgment of the invention are completed by single chip software, the circuit is simple, the realization is easy, and the reliability is high.
Description
Technical Field
The invention relates to the technical field of corner measuring circuits, in particular to a real-time fault judging circuit and method for a potentiometer type corner sensor.
Background
In many occasions, such as an electronic rocker used for remote control operation, steering engine rocker arm rotation angle control, valve opening closed-loop control, liquid level measurement and the like, a rotation angle sensor is needed to convert a measured rotation angle into an electric signal and then measure the electric signal.
There are a number of components for measuring the angle of rotation, with potentiometers being the cheapest and simple measuring component.
A potentiometer is generally a resistive element having three terminals and an output signal that is linearly related to the rotation angle. Usually consisting of a resistive body and a movable brush. When the brush moves along the resistor, a voltage proportional to the rotation angle is obtained at the output end.
A typical potentiometer rotation angle measuring circuit is shown in figure 1, VR is a potentiometer for rotation angle measurement, a reference voltage Vref is connected to the upper end of the potentiometer, a reference ground G is connected to the lower end of the potentiometer, a measured voltage Vx is generated by an electric brush, the position of the electric brush on a resistor body is changed due to the change of a rotation angle, the measured voltage Vx is further changed, and the size of the measured rotation angle can be calculated by the fact that the absolute value of the measured Vx occupies the proportion of the reference voltage Vref.
The equivalent circuit for measuring the rotation angle of a typical potentiometer is shown in fig. 2, and for convenience of analysis, the potentiometer VR is equivalent to 3 elements, namely an upper half resistor Rup, a lower half resistor Rdown and a contact resistor Rcont of a brush and a resistor body, which are divided by a brush. Under normal conditions, the sum of the total resistance Rup and Rdown is the nominal resistance value of the potentiometer VR, and is about 1k omega to dozens of k omega. The contact resistance Rcont is very small, about 1 Ω to 100 Ω. The equivalent load resistance Rload of the measuring circuit is large and is about 100k omega-10M omega.
An output equivalent circuit generated after an upper end resistor Rup and a lower end resistor Rdown which are separated from a potentiometer are converted into an ideal voltage source Vs to drive an equivalent load resistor Rload of a measuring circuit at the position of an electric brush in a typical measuring circuit diagram 1 is shown in fig. 2. In fig. 2, the value of the ideal voltage source Vs is equal to the open-circuit voltage (ideal voltage source) generated by the ideal voltage divider Rup, Rdown acted by the reference voltage Vref, i.e., Vs = Vref + Rdown/(Rup + Rdown). Internal resistance Rs = Rup Rdown/(Rup + Rdown), and it can be seen that Rs is the largest when Rup = Rdown, with a value Rs =1/2 Rup =1/2 Rdown. The brush and the resistor contact resistors Rcont and Rs are connected in series to form the total equivalent internal resistance Rcont + Rs of the potentiometer. Because the range of the upper end resistance Rup and the range of the lower end resistance Rdown are usually 0 omega-dozens of k omega, the internal resistance Rs of the potentiometer is in the range of 0 omega-dozens of k omega.
When the potentiometer is in normal performance, the contact resistance Rcont is in a range of about 1 Ω to 100 Ω. Because the resistor Rs and the contact resistor Rcont are connected in series, the sum of the resistor Rs and the contact resistor Rcont ranges from 1 omega to dozens of k omega when the performance of the potentiometer is normal. The equivalent load resistance Rload of the measuring circuit is large and is about 100k omega-10M omega. As can be seen from fig. 3, the output voltage Vx is equal to Vx generated by voltage division of the ideal voltage source Vs by the equivalent load resistor Rload after the potentiometer internal resistor Rs and the contact resistor Rcont are connected in series, when the sum (Rs + Rcont) of the potentiometer internal resistor Rs and the contact resistor Rcont varies between 1 Ω to several tens of k Ω, the first output voltage Vx1 is approximately equal to the ideal voltage source Vs, and at this time, the influence of the sum (Rs + Rcont) of the potentiometer internal resistor Rs and the contact resistor Rcont on the output voltage Vx can be ignored.
Further transforming fig. 2, combining the load resistance Rload of the measurement circuit with the ideal voltage source Vs and the internal resistance Rs of the potentiometer to obtain an equivalent circuit as shown in fig. 3. Wherein Vx is the output voltage obtained by the measuring circuit. Due to the equivalence, Vx = Vs'. Vs 'is the equivalent voltage source, and Rs' is the equivalent internal resistance of the voltage source. It can be seen that when Rs + Rcont varies between 1 Ω to several tens of k Ω, the equivalent voltage source Vs' is approximately equal to the ideal voltage source Vs, and the influence of Rs + Rcont on the output voltage is negligible. As the potentiometer brush wears, the contact resistance Rcont increases, and it can be seen that when Rcont increases from several tens of Ω to 10% of the load resistance Rload, the voltage of the equivalent voltage source Vs' becomes Vs × Rload/(10% Rload + Rload) = Vs/1.1=0.91 × Vs, which is lower by 9%. It is thus seen that the output voltage variation is affected by the ideal voltage source Vs, and also by the contact resistance Rcont, which has brought about an error of 1-0.91=0.09=9% when Rcont increases to 10% of the equivalent load resistance Rload.
If this condition can be detected before Rcont increases to no more than 1% of the load resistance Rload (i.e., 1k Ω -100 k Ω depending on the load resistance Rload), the measurement error does not exceed 1%, and it can be determined that the potentiometer is faulty early.
The potentiometer VR is a mechanical component, and due to the existence of the brush and the problems of mechanical abrasion and resistance material aging (affecting the upper end resistance Rup and the lower end resistance Rdown) and abrasion and oxidation (affecting the contact resistance Rcont) of the brush in the working process, the defect of poor contact at the later stage of the service life is inevitable. Although the lifetime of the potentiometer VR can be increased by improving the process and materials, the problems of wear and aging are always present due to its mechanical properties.
When the potentiometer VR is used as a sensor, if the potentiometer VR is in a fault state (the upper end resistor Rup or the lower end resistor Rdown is incorrect, and the contact resistor Rcont is overlarge), the correctness of the relation between the output voltage Vx and the rotation angle cannot be guaranteed, at the moment, if the potentiometer is not found to be in the fault state, the potentiometer enters a fault mode in time to perform corresponding processing, an error signal output by the fault potentiometer is used as an execution basis, and serious consequences can be generated on occasions with high requirements on the accuracy of the rotation angle measurement, such as steering engine rocker angle control, valve opening control, remote control rocker angle measurement and the like.
The probability of measurement error can be reduced by using a non-contact sensor such as a Hall sensor and a grating sensor or by performing signal verification operation after two potentiometers VR are coaxially connected, but the non-contact sensor has higher cost and is not suitable for occasions sensitive to cost. Although the cost is not high and the fault of the potentiometer VR can be found through verification after the two potentiometers VR are coaxially connected, the structure and the circuit are relatively complex, the fault rate is improved, two analog-to-digital converters (ADC) are required to be used for measuring the output voltages of the two potentiometers VR respectively, and the cost is doubled.
Disclosure of Invention
The invention aims to provide a real-time fault judging circuit of a potentiometer type rotation angle sensor, which solves the problems of aging, abrasion and sensitivity to cost of a potentiometer brush material in the prior art.
One of the objects of the invention is achieved by: a real-time fault discrimination circuit of a potentiometer type corner sensor is characterized by comprising a potentiometer VR, a bias resistor Rtest and a single chip microcomputer U, wherein the single chip microcomputer U comprises an analog-to-digital converter ADC and an IO port end with push-pull output and high-resistance input; the upper end of the potentiometer VR is connected with a positive terminal X of a reference voltage Vref, the lower end of the potentiometer VR is connected with a reference ground D, and an electric brush is connected with a positive terminal of an output voltage Vx; one end of a bias resistor Rtest is connected to the end of a potentiometer VR brush, and the other end of the bias resistor Rtest is connected to a node A; the power supply voltage VCC end of the singlechip U is connected with the positive terminal X of the reference voltage Vref, the input analog quantity Adin is connected with the electric brush of the potentiometer VR, and the IO port is connected with the node A.
Further, the invention can be realized according to the following technical scheme:
one path of a positive terminal X of the reference voltage Vref is connected with the upper end of the potentiometer VR, and the other path of the positive terminal X of the reference voltage Vref is connected with a power supply voltage VCC end of the singlechip U; the negative terminal Y of the reference voltage Vref is grounded.
The negative end of the output voltage Vx is grounded, and the positive end of the output voltage Vx is connected with an electric brush of the potentiometer VR.
The singlechip U controls a switch K1 and a switch K2, and the IO port end is connected between the switch K1 and the switch K2.
The single chip microcomputer is STM32F103C8T 6.
The potentiometer VR is provided with a plurality of upper ends and lower ends which are connected in parallel, the quantity of the bias resistors Rtest is the same as that of the potentiometer VR, one end of each bias resistor Rtest is connected with an electric brush of the corresponding potentiometer VR, and the other end of each bias resistor Rtest is connected with an IO port of the single chip microcomputer with push-pull output and high-resistance input functions.
The second objective of the present invention is to provide a real-time fault determination method for potentiometer type rotation angle sensor, so as to solve the problem that the prior art cannot perform low-cost real-time fault determination on the potentiometer.
The second purpose of the invention is realized by the following steps: a real-time fault discrimination method for a potentiometer type rotation angle sensor comprises the following steps:
A. the real-time fault discrimination method of the potentiometer type rotation angle sensor is applied to the real-time fault discrimination circuit of the potentiometer type rotation angle sensor in claim 1;
B. the switch K1 and the switch K2 are controlled to be connected by the singlechip U, the output voltage Vx is measured through an analog-digital converter ADC in the singlechip U, the first output voltage Vx1 is obtained, and the internal resistance Rs = Rup Rdown/(Rup + Rdown) of the potentiometer is calculated through the singlechip U;
C. the single chip microcomputer U controls the switch K1 to be switched on, the switch K2 to be switched off and the resistor Rtest to be biased, the output voltage Vx is connected to the reference voltage Vref, the output voltage Vx is measured through an analog-to-digital converter ADC in the single chip microcomputer to obtain a second output voltage Vx2, and the positive current contact resistor Rcont1 is calculated through the single chip microcomputer U as the internal resistor Rs of the potentiometer is obtained through calculation in the step B;
D. the singlechip U controls a switch K2 to be switched on and a switch K1 to be switched off, and the bias resistor Rtest connects the output voltage Vx to the reference ground G; measuring the output voltage Vx through an analog-to-digital converter ADC in the single chip microcomputer to obtain a third output voltage Vx3, and calculating a negative current contact resistance Rcont2 through the single chip microcomputer U as the internal resistance Rs of the potentiometer is obtained through calculation in the step B;
E. judging whether the positive current contact resistance Rcont1 and the negative current contact resistance Rcont2 calculated in the step C or the step D are normal or not through the singlechip U, and if both are normal, calculating a rotation angle by using the first output voltage Vx1 measured in the step B; if the numerical value is abnormal, judging that the potentiometer VR has a fault, and outputting a fault prompt;
F. and repeating the operations of the steps B to E to measure the corner device in real time.
Further, the invention can be realized according to the following technical scheme:
if the values of the positive current contact resistance Rcont1 and the negative current contact resistance Rcont2 exceed the limited value range or the difference between the two exceeds a limited proportion, the values are judged to be abnormal; otherwise, the numerical value is judged to be normal.
The invention sequentially measures the output voltage Vx of the potentiometer VR periodically (5 ms or shorter), calculates the positive current contact resistance Rcont1 and the negative current contact resistance Rcont2, judges whether the potentiometer VR has a fault or not by judging the two values, and outputs the rotation angle through the first output voltage Vx1 if the potentiometer VR does not have the fault. By continuously repeating the operations, whether the potentiometer VR has a fault or not can be judged in real time without influencing the work of the system.
The invention does not increase the number of analog-to-digital converters (ADC) used by a circuit, only increases the offset resistance Rtest and 1 singlechip IO port, has low cost, and utilizes the push-pull output characteristic of the IO port to calculate the value of the positive current contact resistance Rcont1, the value of the negative current contact resistance Rcont2 and the measurement of the angle of rotation (IO high-resistance input mode), thereby completing the indirect measurement of the contact resistance Rcont of the potentiometer and the measurement of the angle of rotation and simultaneously carrying out fault judgment.
The invention can judge the contact resistance of the potentiometer in each measuring period, judge whether the potentiometer VR has a fault or not, and immediately find out the fault when the potentiometer VR fails suddenly so as to avoid serious consequences caused by using wrong measured values. The operation and judgment of the invention are completed by single chip software, the circuit is simple, the realization is easy, and the reliability is high.
Drawings
Fig. 1 is a circuit diagram in the prior art.
Fig. 2 is an equivalent circuit of fig. 1.
Fig. 3 is a further transformed equivalent circuit of fig. 2.
Fig. 4 is a simplified circuit of fig. 5.
Fig. 5 is a circuit diagram of the present invention.
Fig. 6 is an equivalent circuit of fig. 4.
Fig. 7 is a specific circuit diagram of the present invention.
Detailed Description
The following description is given for illustrative embodiments of the invention with reference to the accompanying drawings.
Example 1
As shown in fig. 5, the present invention includes a potentiometer VR, a bias resistor Rtest, and a single chip U including an analog-to-digital converter ADC, and an IO port terminal having a push-pull output and a high-resistance input.
The upper end of the potentiometer VR is connected with a positive terminal X of a reference voltage Vref, the lower end of the potentiometer VR is connected with a reference ground D, and an electric brush is connected with a positive terminal of an output voltage Vx; one end of a bias resistor Rtest is connected to the end of a potentiometer VR brush, and the other end of the bias resistor Rtest is connected to a node A;
the power supply voltage VCC end of the singlechip U is connected with the positive terminal X of the reference voltage Vref, the input analog quantity Adin is connected with the electric brush of the potentiometer VR, and the IO port is connected with the node A. The singlechip U controls a switch K1 and a switch K2, and the IO port end is connected between the switch K1 and the switch K2. The single chip microcomputer is STM32F103C8T 6.
One path of a positive terminal X of the reference voltage Vref is connected with the upper end of the potentiometer VR, and the other path of the positive terminal X of the reference voltage Vref is connected with a power supply voltage VCC end of the singlechip U; the negative terminal Y of the reference voltage Vref is grounded.
The negative end of the output voltage Vx is grounded, and the positive end of the output voltage Vx is connected with an electric brush of the potentiometer VR. The electric brush of the potentiometer VR is connected with the input port of the AD converter of the single chip microcomputer and used for measuring output voltage Vx, and is connected with the IO port end through a bias resistor Rtest and used for providing a bias signal for measuring a contact resistor Rcont. Fig. 6 is an equivalent circuit diagram of fig. 5.
The potentiometer VR can be provided with a plurality of upper ends and lower ends which are connected in parallel, the quantity of the bias resistors Rtest is the same as that of the potentiometer VR, one end of each bias resistor Rtest is connected with an electric brush of the corresponding potentiometer VR, and the other end of each bias resistor Rtest is connected with an IO port of the single chip microcomputer with push-pull output and high-resistance input functions.
Fig. 7 is a specific circuit diagram of the present invention. The singlechip is STM32F103C8T 6. The potentiometer VR is provided with four upper ends and four lower ends which are connected in parallel, and the electric brushes of the potentiometer VR are respectively connected with the corresponding bias resistors Rtest. Specifically, the potentiometer VR1, the potentiometer VR2, the potentiometer VR3 and the potentiometer VR4 are included, and the bias resistor Rtest1, the bias resistor Rtest2, the bias resistor Rtest3 and the bias resistor Rtest4 are correspondingly provided.
The brush of the potentiometer VR1 is connected with the pin 10 of the singlechip STM32F103C8T6, the brush of the potentiometer VR2 is connected with the pin 11 of the singlechip STM32F103C8T6, the brush of the potentiometer VR3 is connected with the pin 12 of the singlechip STM32F103C8T6, and the brush of the potentiometer VR4 is connected with the pin 13 of the singlechip STM32F103C8T 6.
The other end of the bias resistor Rtest1 is connected with a pin 29 of the single chip microcomputer STM32F103C8T6, the other end of the bias resistor Rtest2 is connected with a pin 30 of the single chip microcomputer STM32F103C8T6, the other end of the bias resistor Rtest3 is connected with a pin 31 of the single chip microcomputer STM32F103C8T6, and the other end of the bias resistor Rtest4 is connected with a pin 32 of the single chip microcomputer STM32F103C8T 6.
A port PA0-PA7 of the single chip microcomputer U is internally provided with an analog-to-digital converter ADC which can measure the output voltage Vx of the potentiometer, a port PA8-PA15 is an IO port with high-resistance input and push-pull output and is used for generating offset, and the single chip microcomputer simultaneously measures the voltage and the state of 4 potentiometers.
The output voltage Vx is connected with the input of a voltage measurement analog-to-digital converter ADC of the single chip U, and the value of the voltage measurement analog-to-digital converter ADC is measured for software to calculate. The switch K1 and the switch K2 are IO ports of the singlechip U with high-resistance input and push-pull output functions and are used for switching on and off the bias resistor Rtest. The reference voltage Vref is connected with the power supply of the singlechip U and is also shared with the voltage measurement analog-to-digital converter ADC, so that the cost is reduced.
Because the reference of the analog-digital converter ADC and the potentiometer VR use the same reference voltage, after analog-digital conversion is carried out, voltage units can be eliminated after division operation is carried out on all values of the reference voltage Vref and the output Vx, absolute values of the reference voltage Vref cannot influence a resistance measurement result, and resistance values, not voltage values, are used in the judgment process.
Example 2
The invention discloses a real-time fault discrimination method of a potentiometer type corner sensor, which comprises the following steps:
A. the potentiometer type rotation angle sensor real-time fault determination method is applied to a potentiometer type rotation angle sensor real-time fault determination circuit in embodiment 1, and the circuit diagram is fig. 5, fig. 4 is a simplified circuit of fig. 5, and fig. 6 is an equivalent circuit of fig. 4.
B. And calculating the internal resistance Rs of the potentiometer.
The switch K1 and the switch K2 are connected under the control of the single chip microcomputer U, the output voltage Vx is measured through an analog-digital converter ADC in the single chip microcomputer to obtain a first output voltage Vx1, and the internal resistance Rs = Rup Rdown/(Rup + Rdown) of the potentiometer is calculated through the single chip microcomputer U. Since the contact resistance Rcont is about 1 Ω to several tens of k Ω before the potentiometer VR completely fails, the load resistance Rload has little influence on the output voltage Vx. The first output voltage Vx1 ≈ ideal voltage source Vs at this time. An equivalent ideal voltage source Vs is obtained. Because the reference voltage Vref and the value of Rup + Rdown (nominal resistance value of the potentiometer) are known, the lower end resistor Rdown = (Rup + Rdown) Vx1/Vref can be calculated according to the condition that the voltage division ratio is equal to the resistance ratio Vx1/Vref = Rdown/(Rup + Rdown), and the upper end resistor Rup = (Rup + Rdown) -Rdown is further calculated to calculate the internal resistance Rs = Rup// Rdown of the potentiometer;
C. the positive current contact resistance Rcont1 at positive current bias is calculated.
The switch K1 is turned on under the control of the single chip microcomputer U, the switch K2 is turned off, the resistor Rtest is biased, the output voltage Vx is connected to the reference voltage Vref, the output voltage Vx is measured through an analog-to-digital converter ADC in the single chip microcomputer, a second output voltage Vx2 is obtained, at the moment, Rs + Rcont1= Rtest (Vx2-Vs)/(Vref-Vx2), the potentiometer internal resistance Rs is obtained through calculation in the step B, and the positive current contact resistance Rcont1 can be obtained by subtracting the potentiometer internal resistance Rs from the calculation result.
An extreme case is to be noted, when the brush of the potentiometer VR is at the top, it can be seen from the circuit that the second output voltage Vx2 ≈ ideal voltage source Vs = reference voltage Vref, and after the switch K1 is turned on, the output voltage Vx2= reference voltage Vref, at which time Rs + Rcont1= Rtest (Vx2-Vs)/(Vref-Vx2) = Rtest = (Vref-Vref)/(Vref-Vref) = Rtest = 0/0. At this time, the numerator and denominator will simultaneously appear 0, and the result calculated in this step is invalid and needs to be ignored.
D. The negative current contact resistance Rcont2 at negative current bias is calculated.
The single chip microcomputer U controls the on switch K2 and the off switch K1, and the bias resistor Rtest connects the output voltage Vx to the reference ground G. And measuring the output voltage Vx through an analog-to-digital converter ADC in the single chip microcomputer to obtain a third output voltage Vx3, wherein Rs + Rcont2= Rtest (Vs-Vx2)/Vx 3. Since the internal resistance Rs of the potentiometer is calculated in step B, the negative current contact resistance Rcont2 can be obtained by subtracting the internal resistance Rs of the potentiometer from the result.
An extreme case is to be noted, namely when the brush of the potentiometer VR is at the lowest end, as can be seen from the circuit, the output voltage Vx =0, and when the switch K2 is turned on, a third output voltage Vx3=0 is obtained, at which Rs + Rcont = Rtest (Vs-Vx3)/Vx3= Rtest (0-0)/0. At this time, the numerator and denominator will simultaneously appear 0, and the result calculated in this step is invalid and needs to be ignored.
E. And D, judging whether the positive current contact resistance Rcont1 and the negative current contact resistance Rcont2 calculated in the step C or the step D are normal or not through the single chip microcomputer U, and if the positive current contact resistance Rcont1 and the negative current contact resistance Rcont2 are normal, calculating the rotation angle by using the first output voltage Vx1 measured in the step B. And if the numerical value is abnormal, judging that the potentiometer VR has a fault, and outputting a fault prompt.
If the values of the positive current contact resistance Rcont1 and the negative current contact resistance Rcont2 exceed the limited value range or the difference between the two exceeds a limited proportion, the values are judged to be abnormal; otherwise, the numerical value is judged to be normal.
Specifically, it is determined whether the positive current contact resistance Rcont1 and the negative current contact resistance Rcont2 are within the normal range, and it is determined whether the potentiometer VR is faulty. The positive current contact resistance Rcont1 and the negative current contact resistance Rcont2 are limited to a value range of 10 Ω to 10k Ω, and beyond this range, the data is said to be abnormal. Meanwhile, when the values of the positive current contact resistance Rcont1 and the negative current contact resistance Rcont2 are too different, a percentage of the difference between them exceeding 10% is also considered as data abnormality. Because the contact resistance Rcont is obtained by indirect measurement and has a certain error, in order to achieve the purposes of not misjudging the fault and reliably judging when the fault occurs, the value of 10% can meet the requirement, and the adjustment needs to be combined with the actual condition of the circuit.
The percentage calculation method comprises the following steps: (Rcont 1-Rcont 2)/Rcont2x100% if Rcont1 is different from Rcont2 by some percentage; if Rcont2 differs from Rcont1 by some percentage, (Rcont 2-Rcont 1)/Rcont1x 100%.
F. And repeating the operations of the steps B to E to measure the rotating angle in real time. Since only one measurement result can be obtained by performing the B-E operation once, the rotation angle needs to be measured in real time for real-time control, and the B-E operation needs to be repeatedly performed.
Claims (8)
1. A real-time fault discrimination circuit of a potentiometer type corner sensor is characterized by comprising a potentiometer VR, a bias resistor Rtest and a single chip microcomputer U, wherein the single chip microcomputer U comprises an analog-to-digital converter ADC and an IO port end with push-pull output and high-resistance input functions; the upper end of the potentiometer VR is connected with a positive terminal X of a reference voltage Vref, the lower end of the potentiometer VR is connected with a reference ground D, and an electric brush is connected with a positive terminal of an output voltage Vx; one end of a bias resistor Rtest is connected to the end of a potentiometer VR brush, and the other end of the bias resistor Rtest is connected to a node A; the power supply voltage VCC end of the singlechip U is connected with the positive terminal X of the reference voltage Vref, the input analog quantity Adin is connected with the electric brush of the potentiometer VR, and the IO port is connected with the node A.
2. The real-time fault discrimination circuit of the potentiometer type rotation angle sensor according to claim 1, wherein one path of a positive terminal X of a reference voltage Vref is connected with the upper end of a potentiometer VR, and the other path of the positive terminal X of the reference voltage Vref is connected with a power supply voltage VCC end of a singlechip U; the negative terminal Y of the reference voltage Vref is grounded.
3. The real-time fault discrimination circuit of a potentiometer type rotation angle sensor according to claim 1, wherein the negative terminal of the output voltage Vx is grounded, and the positive terminal is connected with the electric brush of the potentiometer VR.
4. The real-time fault discrimination circuit of the potentiometer type rotation angle sensor according to claim 1, wherein the switch K1 and the switch K2 are controlled by a single chip microcomputer U, and an IO port end is connected between the switch K1 and the switch K2.
5. The real-time fault discrimination circuit of the potentiometer type rotation angle sensor according to claim 1, wherein the single chip microcomputer is STM32F103C8T 6.
6. The real-time fault discrimination circuit of a potentiometer type rotation angle sensor according to claim 1, wherein the potentiometer VR has a plurality of upper and lower ends connected in parallel, the number of the bias resistors Rtest is the same as that of the potentiometer VR, one end of each bias resistor Rtest is connected with a corresponding potentiometer VR electric brush, and the other end of each bias resistor Rtest is connected with an IO port of the single chip microcomputer with push-pull output and high-resistance input functions.
7. A real-time fault discrimination method for a potentiometer type corner sensor is characterized by comprising the following steps:
A. the real-time fault discrimination method of the potentiometer type rotation angle sensor is applied to the real-time fault discrimination circuit of the potentiometer type rotation angle sensor in claim 1;
B. the single chip microcomputer U is used for controlling and connecting a switch K1 and a switch K2, measuring an output voltage Vx through an analog-to-digital converter (ADC) in the single chip microcomputer to obtain a first output voltage Vx1, and calculating internal resistance Rs = Rup Rdown/(Rup + Rdown) of the potentiometer through the single chip microcomputer U;
C. the switch K1 is turned on and the switch K2 is turned off under the control of the single chip microcomputer U, the output voltage Vx is connected to the reference voltage Vref through the bias resistor Rtest, the output voltage Vx is measured through the analog-to-digital converter ADC in the single chip microcomputer, a second output voltage Vx2 is obtained, and the positive current contact resistor Rcont1 is calculated through the single chip microcomputer U as the internal resistance Rs of the potentiometer is obtained through calculation in the step B;
D. the singlechip U controls a switch K2 to be switched on and a switch K1 to be switched off, and the bias resistor Rtest connects the output voltage Vx to the reference ground G; measuring the output voltage Vx through an analog-to-digital converter ADC in the single chip microcomputer to obtain a third output voltage Vx3, and calculating a negative current contact resistance Rcont2 through the single chip microcomputer U as the internal resistance Rs of the potentiometer is obtained through calculation in the step B;
E. judging whether the positive current contact resistance Rcont1 and the negative current contact resistance Rcont2 calculated in the step C or the step D are normal or not through the singlechip U, and if both are normal, calculating a rotation angle by using the first output voltage Vx1 measured in the step B; if the numerical value is abnormal, judging that the potentiometer VR has a fault, and outputting a fault prompt;
F. and repeating the operations of the steps B to E to measure the corner device in real time.
8. The potentiometer type rotation angle sensor real-time fault discrimination method according to claim 7, wherein if the values of the positive current contact resistance Rcont1 and the negative current contact resistance Rcont2 exceed a defined value range or the difference between the two exceeds a first defined ratio, it is determined that the values are abnormal; otherwise, the numerical value is judged to be normal.
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