Hydraulic pressure fault-tolerant processing method for hydraulic retarder

Abstract

The application discloses a kind of hydraulic retarder air pressure fault-tolerant processing methods: step 1, obtain current measured air pressure and valve current of hydraulic retarder;Step 2, respectively judge current measured air pressure, valve current whether normal, yes, then air pressure out-of-range fault flag, valve current out-of-range fault flag is placed 0, otherwise 1 is placed;Step 3, out-of-range fault processing is carried out;Step 4, calculate rationality judgment enabling flag;Step 5, if rationality judgment enabling flag is 0, then output current measured air pressure, otherwise step 6 is executed;Step 6, judge whether the deviation of air pressure and current measured air pressure is greater than tolerance threshold, yes, then measured air pressure rationality fault flag is placed as 1, otherwise 0 is placed;Step 7, if measured air pressure rationality fault flag is 1, report fault and execute step 8, otherwise output current measured air pressure;Step 8, measured air pressure rationality fault processing.The method of the application improves the safety and reliability of retarder control system.

Description

Technical Field

[0001] This invention belongs to the field of automotive electronics technology, specifically relating to a method for handling air pressure fault tolerance in a hydraulic retarder. Background Technology

[0002] A hydraulic retarder is a vehicle auxiliary braking device. The proportional valve is the actuator of the hydraulic retarder. The retarder control system adjusts the retarder chamber pressure by controlling the opening of the proportional valve, thereby controlling the magnitude of the retarder's output braking force. The retarder chamber pressure (referred to as retarder air pressure) is a crucial factor affecting the retarder's braking force. The retarder control system needs to monitor the retarder air pressure in real time to accurately control the retarder's output torque. Therefore, fault-tolerant processing of the retarder air pressure is of great significance to the retarder control system.

[0003] The hydraulic retarder control system monitors the retarder air pressure through a pressure sensor. However, due to limitations in installation space and cost, increasing hardware redundancy cannot improve the signal fault tolerance of the control system. Therefore, it is essential to research a new method for handling hydraulic retarder air pressure faults that can enhance the signal fault tolerance of the control system. Summary of the Invention

[0004] The present invention aims to propose a hydraulic retarder air pressure fault-tolerant processing method to solve the problem of low signal fault tolerance in existing control systems that rely solely on pressure sensors to detect retarder air pressure.

[0005] The retarder control system controls the valve opening by adjusting the proportional valve current. The proportional valve opening directly affects the retarder air pressure. Testing the valve characteristics can obtain the correspondence between "valve current and retarder air pressure," thus allowing for cross-verification of retarder pressure and valve current. A two-dimensional table composed of multiple sets of discrete points for valve current and retarder air pressure is abbreviated as a "current-pressure gauge." For any current within the normal range, a corresponding "theoretical" air pressure value can be obtained by interpolation from the "current-pressure gauge."

[0006] To achieve the above objectives, the present invention employs the following technical solution:

[0007] A method for handling pneumatic fault tolerance in a hydraulic retarder includes the following steps: Step 1: Obtain the current measured air pressure and valve current of the hydraulic retarder, and record them as follows: , ; Step 2: Determine whether the current measured air pressure and valve current are within their respective normal ranges. If they are within the normal range, set the air pressure out-of-range fault flag and valve current out-of-range fault flag to 0; otherwise, set them to 1. Step 3: Handle out-of-range faults according to the air pressure out-of-range fault indicator and the valve current out-of-range fault indicator; Step 4: Calculate the rationality judgment enabling flag. ; Step 5: Enable the flag if reasonableness is determined. If the value is 0, the output air pressure is the current measured air pressure. Otherwise, proceed to step 6; Step 6, Tolerance Judgment: Based on valve current The air pressure is obtained by checking the "current-barometer". Determine air pressure and the current measured air pressure If the deviation is greater than the set tolerance threshold, the measured air pressure reasonableness fault flag is set to 1; otherwise, it is set to 0. Step 7: If the measured air pressure reasonableness fault flag is 1, report a measured air pressure reasonableness fault and proceed to step 8; otherwise, output the current measured air pressure. ; Step 8, Troubleshooting for the Reasonableness of Measured Air Pressure: Regarding the air pressure... and the current measured air pressure The final output air pressure is obtained by weighted processing.

[0008] Furthermore, step 3 includes the following operation: if both the valve current out-of-range fault flag and the air pressure out-of-range fault flag are 0, then proceed to step 4; If the valve current out-of-range fault flag is 0 and the air pressure out-of-range fault flag is 1, then the output air pressure is the current measured valve current. The air pressure is obtained by interpolating from the "current-barometer". ; If the out-of-range air pressure fault flag is 0 and the out-of-range valve current fault flag is 1, then the output air pressure is the current measured air pressure. ; If both the valve current out-of-range fault flag and the air pressure out-of-range fault flag are 1, then the output air pressure will be the preset safe value. This indicates that the current air pressure value is invalid and reports a fault that the current measured air pressure is invalid. Furthermore, step 4 includes the following sub-steps: Step 4.1: Calculate the valve current sequence within the current time period. , , … The difference between the maximum and minimum values ​​of the valve current ,in Indicates the current time; Step 4.2: Build the stateflow flowchart and set state 1: enable flag for rationality judgment. State 1; States 2-5: Reasonableness judgment enable flag Set the value to 0, and start timing when entering this state, with an initial timing value of 0; judge The interval in which the reasonableness judgment is obtained is enabled by the flag. ; Set the valve current change thresholds in ascending order. , … The valve current variation range is divided into different intervals, and a corresponding delay time is set. , … The greater the change in valve current, the longer the delay time. in, , … as well as , … These are empirical values ​​obtained based on the valve current adjustment results, where This is the upper limit of the normal fluctuation range of the valve current when the target air pressure remains unchanged; Furthermore, when m=4, the specific judgment logic is as follows: if Less than Enter state 1; until Exit status 1, re-evaluate The range in which it is located; if Between and Between, enter state 2; until the timer exceeds or Exit status 2, re-evaluate The range in which it is located; if Between and Between, enter state 3; until the timer exceeds or Exit status 3, re-evaluate The range in which it is located; if Between and Between, enter state 4; until the timer exceeds or Exit status 4, re-evaluate The range in which it is located; if Greater than Enter state 5; until the timer exceeds Exit status 5, reassess The interval in which it is located.

[0009] Furthermore, in step 8, the calculation formula is as follows: ; in, This is the final output air pressure; , As weight, ,and .

[0010] As described above, this invention processes the measured air pressure fed back by the pressure sensor, filters out obviously erroneous data and makes a reasonable judgment to ensure the consistency and reliability of the control system data, and then uses the processed air pressure to participate in the retarder control, thereby improving the safety and stability of the retarder control system.

[0011] Compared with the prior art, the present invention has the following beneficial effects: This invention proposes a fault-tolerant processing method for measured air pressure in a hydraulic retarder control system, based on existing signals without increasing system hardware costs. By detecting invalid and reasonable faults in the measured air pressure and proposing corresponding processing strategies for various situations, a safe and reliable air pressure value is obtained to participate in the retarder control. This effectively solves the problem of low signal fault tolerance in existing control systems that only detect retarder air pressure through pressure sensors, thereby improving the safety and reliability of the retarder control system. Attached Figure Description

[0012] Figure 1 This is a flowchart of the hydraulic retarder air pressure fault-tolerant processing method provided by the present invention.

[0013] Figure 2 A schematic diagram of the process for determining the reasonableness of air pressure using the enable flag.

[0014] Figure 3 This is a schematic diagram showing the relationship between the proportional valve current and the retarder air pressure.

[0015] Figure 4 This is a schematic diagram of the air pressure fault tolerance result when a reasonableness fault is triggered due to an abnormal measured air pressure, as an embodiment of the present invention. Detailed Implementation

[0016] The present invention will be described in detail below with reference to the accompanying drawings. The present invention includes, but is not limited to, the following embodiments.

[0017] The following implementation uses a hydraulic retarder as an example. The retarder's actuator is a proportional valve. Multiple sets of discrete current and air pressure data have been obtained by testing the valve's characteristics, thus generating a current-pressure gauge. Under normal circumstances, the retarder's measured air pressure range is 0~3.0 bar, and the valve current range is 0-750 mA.

[0018] Please see Figure 1 The present invention provides a method for handling pneumatic fault tolerance in a hydraulic retarder, comprising the following steps: Step 1: Obtain the current measured air pressure and valve current of the hydraulic retarder, and record them as follows: , .

[0019] Step 2: Determine whether the current measured air pressure and valve current are within their respective normal ranges. If they are within the normal range, set the air pressure out-of-range fault flag and valve current out-of-range fault flag to 0; otherwise, set them to 1. Step 3, Out-of-range fault handling: If both the valve current out-of-range fault flag and the air pressure out-of-range fault flag are 0, proceed to step 4. If the valve current out-of-range fault flag is 0 and the air pressure out-of-range fault flag is 1, then the output air pressure is the current measured valve current. The air pressure is obtained by interpolating from the "current-barometer". Among them, the "current-barometer" is a common gauge in the field, such as... Figure 3 The schematic diagram of the proportional valve current-retarder air pressure relationship shown is the equivalent diagram of the current-air pressure gauge.

[0020] If the out-of-range air pressure fault flag is 0 and the out-of-range valve current fault flag is 1, then the output air pressure is the current measured air pressure. ; If both the valve current out-of-range fault flag and the air pressure out-of-range fault flag are 1, then the output air pressure is a pre-approved safe value. (In this embodiment, it is 3.5 bar), indicating that the current air pressure value is invalid, and reporting a fault that the current measured air pressure is invalid. Step 4: Calculate the rationality judgment enable flag. Please see Figure 2 It includes the following steps: Step 4.1: Calculate the valve current sequence within the current time period. , , … The difference between the maximum and minimum values ​​of the valve current ,in Indicates the current moment; Based on valve control performance, this embodiment selects a valve current sequence within 500ms, and the module execution cycle is 100ms. The value is 4.

[0021] Step 4.2: Build the stateflow flowchart and set state 1: enable flag for rationality judgment. State 1; States 2-5: Reasonableness judgment enable flag Set the value to 0, and start timing when entering this state, with an initial timing value of 0; judge The interval in which the reasonableness judgment is obtained is enabled by the flag. .

[0022] Set the valve current change thresholds in ascending order. , … The valve current variation range is divided into different intervals, and a corresponding delay time is set. , … The greater the change in valve current, the longer the delay time. in, , … as well as , … These are empirical values ​​obtained based on the valve current adjustment results, where This represents the upper limit of the normal fluctuation range of the valve current when the target air pressure remains unchanged. In this embodiment, m=4. =10mA, , , , = 0.5s, = 1s, = 2s, =3s.

[0023] The specific judgment logic is as follows: if Less than Enter state 1; until Exit status 1, re-evaluate The area in question; if Between and Between, enter state 2; until the timer exceeds or Exit status 2, re-evaluate The range in which it is located; if Between and Between, enter state 3; until the timer exceeds or Exit status 3, re-evaluate The range in which it is located; if Between and Between, enter state 4; until the timer exceeds or Exit status 4, re-evaluate The range in which it is located; if Greater than Enter state 5; until the timer exceeds Exit status 5, reassess The range in which it is located; Step 5: Enable the flag if reasonableness is determined. If the value is 0, the output air pressure is the current measured air pressure. Otherwise, proceed to step 6; Step 6, Tolerance Judgment: Based on valve current The air pressure is obtained by checking the "current-barometer". Determine air pressure and the current measured air pressure If the deviation exceeds the set tolerance threshold, the measured air pressure reasonableness fault flag is set to 1; otherwise, it is set to 0. The tolerance threshold is determined based on the air pressure control performance. In this embodiment, the tolerance threshold is selected as 30 kPa.

[0024] Step 7: If the measured air pressure reasonableness fault flag is 1, report a measured air pressure reasonableness fault and proceed to step 8; otherwise, output the current measured air pressure. ; Step 8, Troubleshooting for the Reasonableness of Measured Air Pressure: Regarding the air pressure... and the current measured air pressure The final output air pressure is obtained through weighted processing. The calculation formula is as follows: ; in, This is the final output air pressure; , For weighting and considering driving safety, as an auxiliary braking device, the harm of insufficient braking force output by the retarder is less than the harm of excessive braking force. The output air pressure ultimately participates in closed-loop control, so it should be higher rather than lower. To avoid the retarder mistakenly outputting excessive braking force, this invention sets the maximum value to have a higher weighting, i.e. ,and The specific value is determined conventionally based on the debugging results. In this embodiment, Take 0.85.

[0025] Please see Figure 4 The figure shows the test results of a preferred embodiment of the present invention. The air pressure received by the control system has an abnormal sudden change, which triggers a rationality fault. By comparing the output air pressure and input air pressure after fault tolerance processing with the actual air pressure, it can be seen that the method of the present invention can obtain more reliable air pressure and the application effect is significant.

Claims

1. A method for handling pneumatic fault tolerance in a hydraulic retarder, characterized in that, Includes the following steps: Step 1: Obtain the current measured air pressure and valve current of the hydraulic retarder, and record them as follows: , ; Step 2: Determine whether the current measured air pressure and valve current are within their respective normal ranges. If they are within the normal range, set the air pressure out-of-range fault flag and valve current out-of-range fault flag to 0; otherwise, set them to 1. Step 3: Handle out-of-range faults according to the air pressure out-of-range fault indicator and the valve current out-of-range fault indicator; Step 4: Calculate the rationality judgment enabling flag. ; Step 5: Enable the flag if reasonableness is determined. If the value is 0, the output air pressure is the current measured air pressure. Otherwise, proceed to step 6; Step 6, Tolerance Judgment: Based on valve current The air pressure is obtained by checking the "current-barometer". Determine air pressure and the current measured air pressure If the deviation is greater than the set tolerance threshold, the measured air pressure reasonableness fault flag is set to 1; otherwise, it is set to 0. Step 7: If the measured air pressure reasonableness fault flag is 1, report a measured air pressure reasonableness fault and proceed to step 8; otherwise, output the current measured air pressure. ; Step 8, Troubleshooting for the Reasonableness of Measured Air Pressure: Regarding the air pressure... and the current measured air pressure The final output air pressure is obtained by weighted processing.

2. The hydraulic retarder pneumatic fault-tolerant processing method as described in claim 1, characterized in that, Step 3 includes the following operations: If both the valve current out-of-range fault flag and the air pressure out-of-range fault flag are 0, proceed to step 4. If the valve current out-of-range fault flag is 0 and the air pressure out-of-range fault flag is 1, then the output air pressure is the current measured valve current. The air pressure is obtained by interpolating from the "current-barometer". ; If the out-of-range air pressure fault flag is 0 and the out-of-range valve current fault flag is 1, then the output air pressure is the current measured air pressure. ; If both the valve current out-of-range fault flag and the air pressure out-of-range fault flag are 1, then the output air pressure is a pre-approved safe value. This indicates that the current air pressure value is invalid and reports a fault indicating that the current measured air pressure is invalid.

3. The hydraulic retarder pneumatic fault-tolerant processing method as described in claim 2, characterized in that, Step 4 includes the following sub-steps: Step 4.1: Calculate the valve current sequence within the current time period. , , … The difference between the maximum and minimum values ​​of the valve current ,in Indicates the current time; Step 4.2: Build the stateflow flowchart and set state 1: enable flag for rationality judgment. State 1; States 2-5: Reasonableness judgment enable flag Set the value to 0, and start timing when entering this state, with an initial timing value of 0; judge The interval in which the reasonableness judgment is obtained is enabled by the flag. ; Set the valve current change thresholds in ascending order. , … The valve current variation range is divided into different intervals, and a corresponding delay time is set. , … The greater the change in valve current, the longer the delay time. in, , … as well as , … These are empirical values ​​obtained based on the valve current adjustment results, where This is the upper limit of the normal fluctuation range of the valve current when the target air pressure remains unchanged.

4. The hydraulic retarder pneumatic fault-tolerant processing method as described in claim 3, characterized in that, When m=4, the specific judgment logic is as follows: if Less than Enter state 1; until Exit status 1, re-evaluate The range in which it is located; if Between and Between, enter state 2; until the timer exceeds or Exit status 2, re-evaluate The range in which it is located; if Between and Between, enter state 3; until the timer exceeds or Exit status 3, re-evaluate The range in which it is located; if Between and Between, enter state 4; until the timer exceeds or Exit status 4, re-evaluate The range in which it is located; if Greater than Enter state 5; until the timer exceeds Exit status 5, reassess The interval in which it is located.

5. The hydraulic retarder pneumatic fault-tolerant processing method as described in claim 4, characterized in that, In step 8, the calculation formula is as follows: ； in, This is the final output air pressure; , As weight, ,and .

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