CN104834210B - A Redundant Control Method Based on Dual Position Sensors - Google Patents

Abstract

A kind of redundancy control method based on two-position sensor, redundancy judging module carries out extreme value fault distinguishing to the output valve of two position sensors of servo-drive system, the output valve for not occurring extreme value location of fault sensor is selected to be exported, if two position sensors all do not occur extreme value failure, then carry out two-way feedback consistency discrimination, if two-way feedback is consistent, keep the output of current position sensor constant, if two-way feedback is inconsistent, then carry out null value fault distinguishing, the output valve for not occurring null value location of fault sensor is selected to be exported, if two position sensors all do not occur null value failure, feedback is then carried out with command error to differentiate, the output valve of the output valve position sensor small with the absolute value of the error amount of instruction is exported.The present invention realizes that simply failure compatibility is good, and reliability is high.

Description

A Redundant Control Method Based on Dual Position Sensors

technical field

The invention relates to a redundant control method based on dual position sensors.

Background technique

The servo system is an important attitude and orbit control execution subsystem of the launch vehicle. By collecting the position feedback signal in real time and comparing it with the position command signal, the position closed-loop control is formed to realize the position tracking of the load. The position sensor is an important part of the position output of the servo system, and its reliability is very important.

Usually the failure rate of the position sensor is high. In order to improve the reliability, most of them adopt redundant technology at present, such as the method of "connecting the output ends of two position sensors in parallel" used on the launch vehicle in active service. It is effective, but when there is an open circuit fault in one feedback power supply, the actual feedback output value will deviate. The new generation of launch vehicles uses an integrated three-redundant position sensor, and adopts a redundant judgment method of "out of three". However, for small servo systems with strict requirements on volume and weight, it is difficult for the existing three-redundant position sensor to achieve a small size. requirements.

Contents of the invention

The invention provides a redundant control method based on dual position sensors, which has the advantages of simple realization, good fault compatibility and high reliability.

In order to achieve the above object, the present invention provides a redundant control method based on dual position sensors, comprising the following steps:

Step A, the redundant judgment module performs extreme fault judgment on the output values of the two position sensors of the servo system:

If the absolute values of the output values of the two position sensors are greater than the extreme value fault judgment threshold Uy1, it means that both position sensors have an extreme value fault, and the control output that actually controls the action of the servo mechanism is set to zero to prevent stall damage Servo mechanism; if the absolute value of the output value of any one of the position sensors in the two position sensors is greater than the extreme value fault judgment threshold Uy1, then the output value of the other position sensor whose absolute value of the output value is less than the extreme value fault judgment threshold Uy1 As the output value Uf of the position sensor; if the absolute value of the output value of the two position sensors is less than the extreme value fault judgment threshold Uy1, the two-way feedback consistency judgment is carried out;

Step B, the redundant judgment module performs two-way feedback consistency judgment on the output values of the two position sensors of the servo system:

If the absolute value of the difference between the output values of the two position sensors is less than the two-way feedback signal consistency decision threshold Uy3, it means that the two-way feedback is consistent, and the current output of the position sensor remains unchanged;

If the absolute value of the difference between the output values of the two position sensors is greater than the two-way feedback signal consistency judgment threshold Uy3, indicating that the two-way feedback is inconsistent, then carry out zero-value fault discrimination;

Step C, redundant judgment module carries out zero value fault judgment to the output value of two position sensors of servo system:

If the absolute value of the output value of any one of the two position sensors is less than the zero-value fault judgment threshold Uy2, it indicates that a zero-value fault has occurred, and the absolute value of the other output value is greater than the zero-value fault judgment threshold Uy2. The output value of the sensor is used as the output value Uf of the position sensor;

If the absolute values of the output values of the two position sensors are greater than the zero-value fault judgment threshold Uy2, the feedback and command error judgment is performed.

Step D, the redundant judgment module performs feedback and command error judgment on the output values of the two position sensors of the servo system:

The absolute value of the error value between the output values of the two position sensors and the command is compared, and the output value of the position sensor with the smaller absolute value of the error value between the output value and the command is taken as the output value Uf of the position sensor.

The extreme value fault judgment threshold Uy1 is greater than the maximum swing angle value Ub of the servo system and smaller than the fault extreme value Uj.

The zero-value fault judgment threshold Uy2=0.2V.

The two-way feedback signal consistency decision threshold Uy3≥1.5ΔUf, wherein ΔUf is the maximum deviation value of the two-way feedback potentiometers.

The present invention has the following advantages:

1. The redundant judgment module is an independent software module, and all of them are logical judgment statements. It does not involve complex calculations and is simple to implement. It is basically applicable to servo systems equipped with two-way position sensors on the hardware. At the same time, it can be extended to be equipped with three-way and A system of position sensors above;

2. It covers a wide range of failure modes, and the typical position sensor failure modes can basically be covered, and the failure compatibility is good;

3. The two position sensor channels allow multiple switches, which can effectively prevent the risk of false switching caused by a single switch. For example, when the value of a certain beat or several beats has an outlier value, the position feedback channel is switched from one way to another. One way (actually, the output of the current way is still normal), if the other way fails later, it can still be switched back again, which further improves the reliability of the position sensor feedback loop.

Description of drawings

Figure 1 is a schematic diagram of the output of a position sensor.

Fig. 2 is a flow chart of an embodiment of a redundant control method based on dual position sensors provided by the present invention

Fig. 3 is a curve diagram of the test situation when the feedback of the main position sensor and the auxiliary position sensor are respectively injected with a zero-value fault.

detailed description

A preferred embodiment of the present invention will be specifically described below with reference to FIGS. 1 to 3 .

The servo system of a new-generation launch vehicle uses existing resources according to the space layout requirements and uses two independent small position sensors (single weight 15g). The two position sensors 101 are distributed on both sides of the output shaft of the servo mechanism. Detect the swing angle output of the servo mechanism.

As shown in Figure 1, the structure of the position sensor 101 is similar to a sliding rheostat, the position sensor 101 has a feedback negative power supply terminal 1, a feedback positive power supply terminal 3 and a feedback output terminal 2, a feedback negative power supply terminal 1 and a feedback output terminal Between the terminals 2 is the A-B section resistance matrix, and between the feedback positive power supply terminal 3 and the feedback output terminal 2 is the B-C section resistance matrix.

According to the structure of the position sensor, the failure modes of the position sensor and the failure results of each failure mode are listed, as shown in Table 1 below.

Table 1 Feedback potentiometer failure mode and result

It can be seen from Table 1 that although there are many failure modes (without considering the short-circuit fault of lines 1 and 3 and the short-circuit fault of lines 1 and 4), there are only two typical failure results as follows:

1. Extreme value fault result: the feedback output value is the maximum value of positive or negative;

2. Zero-value fault results: the feedback output value is a definite value within the range of -0.1V to 0.1V (feedback suspension voltage, by setting a pull-down resistor on the hardware circuit, the output voltage range when the feedback output terminal is suspended can be guaranteed to be within this feedback suspension voltage range).

For extreme value faults, because the fault output is generally far beyond the voltage range of the effective swing angle, it is easy to judge; for zero value faults, because it is within the effective voltage range, it is relatively difficult to judge, and the focus of the redundant control method lies in this.

The output of the position sensor under normal and fault conditions has the following three situations:

1. When there is no fault, the feedback output value can be any value within the effective swing angle range;

2. When an extreme value fault occurs, the feedback output value is positive or negative maximum value;

3. When a zero-value fault occurs, the feedback output value is a constant value within the range of -0.1V to +0.1V.

However, even if the feedback output value falls within the range of -0.1V to +0.1V, there are two situations:

3.1. There is no fault in the feedback, but the feedback passes through the area of -0.1V～+0.1V or the feedback remains in this area;

3.2. There is a zero-value fault in the feedback.

As shown in Figure 2, the present invention provides a redundant control method based on dual position sensors, the redundant control method is used for the output control of the main position sensor and the auxiliary position sensor of the servo system, Uf _a is the output of the main position sensor value, Uf _b is the output value of the auxiliary position sensor, efa is the error value between the output value of the main position sensor and the instruction, efb is the error value between the output value of the auxiliary position sensor and the instruction, and Uf is the position sensor selected to participate in the closed-loop control Output value, set the current output value as the output value of the main position sensor.

The described redundant control method based on dual position sensors comprises the following steps:

Step S1, the redundant judgment module sets the extreme value fault judgment threshold Uy1, the zero value fault judgment threshold Uy2 and the two-way feedback signal consistency judgment threshold Uy3;

The extreme value fault judgment threshold Uy1 is used for extreme value fault judgment, and the threshold is between the maximum swing angle value Ub of the servo system and the fault extreme value Uj (positive or negative maximum value), that is, Ub<Uy1<Uj;

The zero-value fault judgment threshold Uy2 is used for zero-value fault judgment, and this value leaves a margin of 2 times on the basis of the 0.1V boundary value, that is, Uy2=0.2V;

The two-way feedback signal consistency judgment threshold Uy3 is used for the consistency judgment of the two-way feedback signals. Because the two-way feedback potentiometers are independent of each other, there are also differences in the linearity of the two within a given swing angle range. On the basis of the maximum deviation value ΔUf of the two feedback potentiometers, there is a margin of at least 0.5 times, that is, Uy3≥1.5ΔUf;

When it comes to logical judgments compared with the thresholds Uy1, Uy2, and Uy3, since the threshold itself has a certain margin, the situation that the judgment results are equal may not be considered;

Step S2, the redundant judgment module judges whether |Ufa|>Uy1 and |Ufb|>Uy1 are satisfied; if yes, it means that both feedbacks have extreme value faults (that is, the absolute value of the feedback output is greater than the threshold value Uy1), and the position sensor will be controlled Set the control output to zero (that is, set the torque output of the servo mechanism to zero) to prevent the servo mechanism from swinging to the maximum mechanical limit and stalling, then return to step S2 and continue to judge; if not, proceed to step S3;

Step S3, the redundancy judgment module judges whether |Ufa|<Uy1 and |Ufb|>Uy1 are satisfied; if so, it means that the current feedback value is normal, and the other feedback value has an extreme value fault, and the current feedback output is still selected, and returns to step S2; If not, proceed to step S4;

Step S4, the redundant judgment module judges whether |Ufa|>Uy1 and |Ufb|<Uy1 are satisfied; if yes, it means that the current feedback value has an extreme value fault, and the other feedback value is normal, and another feedback output is selected instead, and the return step S2; if not, go to step S5;

Step S5, the redundant judgment module judges whether |Ufa-Ufb|<Uy3 is satisfied; if it is, it means that the two feedback outputs are consistent (that is, the absolute value of the error between the two feedbacks is less than the threshold Uy3), still select the current feedback output, and return to the step S2; if not, it means that the two feedbacks are inconsistent, then go to step S6;

Step S6, the redundant judgment module judges whether |Ufb|<Uy2 is satisfied; if it is, it means that this feedback has a zero value (that is, the absolute value of the feedback output is less than Uy2), then select another feedback output, and return to step S2; if not, then Go to step S7;

Step S7, the redundant judgment module judges whether |Ufa|<Uy2 is satisfied; if it is, it means that the current feedback has a zero value, then select another feedback output, and return to step S2; if not, go to step S8;

Step S8, the redundant judgment module judges whether (|efa|-|efb|)>0; if so, it means that the error between the main feedback and the command is larger than the error between the secondary feedback and the command, select another feedback output, and return to the step S2; if not, it means that the error between the main feedback and the instruction is smaller than the error between the auxiliary feedback and the instruction, and the current feedback output is still selected, and returns to step S2.

Step S2-Step S4 is used for judging extreme value faults, step S5 is used for two-way feedback consistency judgment, step S6-step S7 is used for judging zero-value faults, and step S8 is used for judging two-way feedback and command error judgment.

For the two typical fault results of zero-value fault and extreme-value fault, the feedback redundancy strategy is designed according to the process of "extreme-value fault discrimination → two-way feedback consistency judgment → zero-value fault judgment → feedback and command error judgment". The feedback loop (that is, the loop currently participating in the closed-loop control) is initially set as the main feedback loop, allowing multiple switching of the two feedback loops to prevent the risk of false switching caused by a single switching.

Through external injection of typical failure modes, the redundant control method based on dual position sensors provided by the present invention has been tested in three situations, and the test results are as follows:

1. When the two position sensors are not faulty, the feedback from the main position sensor is always selected, and there is no wrong switching;

2. The feedback of the main position sensor is normal, and when the feedback injection of the auxiliary position sensor fails, the feedback of the main position sensor is always selected, and there is no wrong switching;

3. When the feedback injection fault of the main position sensor and the feedback of the auxiliary position sensor are not faulty, when an extreme value fault is injected into the feedback channel of the main position sensor, fast feedback channel switching can be realized; when a zero value fault is injected, the system is There will be short-term small fluctuations during the switching process, and then return to normal. On this basis, the feedback output of the main position sensor is restored to normal, and the fault is injected into the feedback output of the auxiliary position sensor, then the system can switch to the main feedback again.

Figure 3 is the test situation when the main and auxiliary feedbacks inject zero-value faults. At T1, the main feedback is injected with zero-value faults. After the fault injection, the servo system has a short-term small vibration and then switches to the auxiliary feedback output; after that, the main feedback is restored. Normal, a zero-value fault is injected into the auxiliary feedback at T2, and after the fault is injected, the servo system oscillates for a short time and then switches to the main feedback output.

The present invention adds a redundant judgment module (the program does not exceed 30 lines), and the module is all logical judgment sentences, which does not involve complex calculations, so the operating burden of the software will not be increased. The redundant control algorithm is simple to implement and has good compatibility. It can effectively identify and eliminate the typical failure mode of the position sensor. When the output of the current position sensor is normal, there will be no switching. When the output of the current position sensor is faulty and the other is normal, Effective switching can be realized, and the present invention is suitable for servo systems or similar systems (products) that have two position sensors in hardware configuration and require high reliability of position feedback loops.

Although the content of the present invention has been described in detail through the above preferred embodiments, it should be understood that the above description should not be considered as limiting the present invention. Various modifications and alterations to the present invention will become apparent to those skilled in the art upon reading the above disclosure. Therefore, the protection scope of the present invention should be defined by the appended claims.

Claims (5)

1. A redundant control method based on dual position sensors, characterized in that, comprising the following steps: Step A, the redundant judgment module performs extreme fault judgment on the output values of the two position sensors of the servo system: If the absolute values of the output values of the two position sensors are greater than the extreme value fault judgment threshold Uy1, it means that both position sensors have an extreme value fault, and the control output that actually controls the action of the servo mechanism is set to zero to prevent stall damage Servo mechanism; if the absolute value of the output value of any one of the position sensors in the two position sensors is greater than the extreme value fault judgment threshold Uy1, then the output value of the other position sensor whose absolute value of the output value is less than the extreme value fault judgment threshold Uy1 As the output value Uf of the position sensor; if the absolute value of the output value of the two position sensors is less than the extreme value fault judgment threshold Uy1, the two-way feedback consistency judgment is carried out; Step B, the redundant judgment module performs two-way feedback consistency judgment on the output values of the two position sensors of the servo system: If the absolute value of the difference between the output values of the two position sensors is less than the two-way feedback signal consistency decision threshold Uy3, it means that the two-way feedback is consistent, and the current output of the position sensor remains unchanged; If the absolute value of the difference between the output values of the two position sensors is greater than the two-way feedback signal consistency judgment threshold Uy3, indicating that the two-way feedback is inconsistent, then carry out zero-value fault discrimination; Step C, redundant judgment module carries out zero value fault judgment to the output value of two position sensors of servo system: If the absolute value of the output value of any one of the two position sensors is less than the zero-value fault judgment threshold Uy2, it indicates that a zero-value fault has occurred, and the absolute value of the other output value is greater than the zero-value fault judgment threshold Uy2. The output value of the sensor is used as the output value Uf of the position sensor; If the absolute values of the output values of the two position sensors are greater than the zero-value fault judgment threshold Uy2, the feedback and command error judgment is performed. 2. The redundant control method based on dual position sensors as claimed in claim 1, wherein the redundant control method based on dual position sensors also comprises step D, which is performed after step C; Step D, the redundant judgment module performs feedback and command error judgment on the output values of the two position sensors of the servo system: The absolute value of the error value between the output values of the two position sensors and the command is compared, and the output value of the position sensor with the smaller absolute value of the error value between the output value and the command is taken as the output value Uf of the position sensor. 3 . The redundant control method based on dual position sensors according to claim 1 , wherein the extreme value fault judgment threshold Uy1 is greater than the maximum swing angle value Ub of the servo system and smaller than the fault extreme value Uj. 4 . 4. The redundant control method based on dual position sensors according to claim 1, characterized in that the zero-value fault judgment threshold Uy2=0.2V. 5. The redundant control method based on dual position sensors as claimed in claim 1, characterized in that, the two-way feedback signal consistency decision threshold Uy3≥1.5ΔUf, wherein ΔUf is the maximum value of the two-way feedback potentiometer Deviation.