CN105629951A - Reconstruction method of sensor signal in engine experimental environment - Google Patents

Abstract

The invention discloses a method for reconstructing sensor signals in an engine experiment environment, and belongs to the field of engine research and development. The upper computer reads each sensor signal and saves it in a certain format, and its data corresponds to the value of each sensor signal one by one. After reading the sensor value and determining the data type in the upper computer, the actual electrical signal is solved according to the output characteristic formula of the static calibration of the sensor. When solving, the value range is limited to ensure the validity of the solution, and the actual electrical signal is saved as The input of the lower computer realizes the reconstruction of the sensor signal, and then establishes a virtual experiment environment.

Description

A Reconstruction Method of Sensor Signals in Engine Experimental Environment

technical field

The invention relates to a sensor signal reconstruction method, in particular to a sensor signal reconstruction method in an engine experiment environment, and belongs to the field of engine research and development.

Background technique

During the development process of the engine ECU, signal generators are usually used in the laboratory to simulate various sensor signals of the engine, such as the speed, throttle position, etc., before the bench test verification, and use them as the input variables of the ECU to process the input through the program Finally, various actuators are controlled to achieve the purpose of controlling the normal operation of the engine. Since the output waveform of the signal generator is too ideal, and the actual output signal of the engine sensor will have certain burrs, which is not smooth. During the bench test, if the signal generator is used to simulate various sensor signals of the engine to generate control signals for the engine ECU Strategies to control engine experiments will fail to achieve the intended purpose of the experiment.

Under the experimental environment of the engine, the signals of various sensors are constantly changing, and there is no clear change rule. In the steady-state condition, the control strategy of the engine ECU is corrected on the basis of various sensor signals, while in the experimental environment, the work of the engine ECU is affected by the comprehensive influence of various parameters. If a single signal It is inaccurate to judge the engine ECU by the change of the engine ECU. It is necessary to provide multiple sensor signals to the engine ECU at the same time, and the signal generator cannot simulate the input of multiple engine signals at the same time.

Contents of the invention

The technical problem to be solved by the present invention is to overcome the defects of the prior art, and provide a method for reconstructing sensor signals in an engine experiment environment that can reproduce various sensor signals to meet the needs of engine experiment development.

In order to solve the above-mentioned technical problems, the reconstruction method of the sensor signal under the engine experiment environment provided by the present invention comprises the following steps:

1), the host computer reads the signals of each sensor and saves them at intervals according to the format set; the signals of the same sensor are saved at intervals;

2) The host computer analyzes the signals of each sensor, and after determining each signal type, calculates the respective actual output signal y through the output characteristics of the sensors:

y＝a ₀ +a ₁ x+a ₂ x ² +…+a _n x ⁿ

In the formula, x is the input of the sensor, a ₀ is the zero output, a ₁ is the linear sensitivity of the sensor, a ₂ ,..., a _n are the undetermined constants of the nonlinear term;

3), determine whether each actual output signal y obtained in step 2) exceeds the value range of the corresponding sensor, and discard it if it exceeds; if it meets, store each actual output signal y at an interval T as the input of the lower computer during the experiment .

In the present invention, the interval time T is shorter than the interval time for the host computer to read the signals of each sensor.

The beneficial effects of the present invention are: (1), store the various signals of the engine at different times read by the upper computer, and store after solving the actual output signal y of each sensor at different times, and input it to the lower computer at intervals as Output, avoiding the output waveform of the signal generator is too ideal, can not approach the deficiencies of various sensor signals of the engine in the actual environment, and improve the reliability of the development of the engine ECU; (2), the present invention can provide multi-channel sensor signals to the engine ECU at the same time, Realize the reconstruction of multiple sensor signals, establish a virtual experiment environment closer to reality, and make the engine experiment control more accurate.

Description of drawings

Figure 1 is a block diagram of sensor signal reconstruction in the engine experiment environment;

Figure 2 is an example of data saving text;

Fig. 3 is a flow chart of establishing the corresponding relationship between the sensor signal and the ECU input signal;

Fig. 4 The change curve of the reconstructed rotational speed signal under the engine cold start condition;

detailed description

The present invention will be described in further detail below in conjunction with the accompanying drawings.

As shown in Figure 1, the reconstruction method of sensor signal under the engine experiment environment of the present invention, concrete process is as follows:

Step 1. Various physical signals of the engine include temperature signals, intake air pressure signals, battery voltage signals, throttle opening signals, crankshaft and camshaft signals, knock signals, and oxygen sensor signals; among them, temperature signals, intake air pressure signals , The battery voltage signal and the throttle opening signal are all analog signals, and the crankshaft and camshaft signals are pulse signals. The upper computer reads the signals of each sensor, and saves the temperature, throttle opening, engine speed, battery voltage, intake pressure and other signals collected by each sensor in the form of TXT text. The time interval for saving data in TXT text is 1s. The TXT text corresponds to the signal value of each sensor one by one.

As shown in Figure 2, in the TXT text, the first row is the name of each sensor signal saved, that is, the data type and unit, the first column is the serial number of the saved data, and the following ones correspond to the data values collected by each sensor in turn, and finally One column is the time to save the data. When the data value is blank, it means that the data of the sensor has not been collected; the data file is only accurate to the second, and each second corresponds to one or two data points. In the process of collecting sensor signals, there are far more than these types of data, which can be changed according to the actual use, but the format of the data is determined.

Step 2. In the TXT data text saved by the upper computer, the physical signal value corresponding to each sensor is displayed, and the output of the lower computer (ECU) is an electrical signal equivalent to the voltage output by the sensor, corresponding to the input and output of each sensor. The output signal, so the link between the sensor signal and the engine ECU signal simulation system is the output characteristic relationship of the sensor. At the same time, the signal output by the simulation system must conform to the output characteristics of the sensor and cover the working range of the sensor.

To establish the corresponding relationship between the sensor input signal and the final output signal to the ECU, four items need to be input: data type, sensor output characteristic formula, data value range and data value.

1), determine the data type

There are three types of lower computer (ECU) input signals: analog signal, switch signal, and pulse signal. It is necessary to determine the type of sensor signal that needs to be simulated in the data text. For example, the throttle opening signal is an analog signal.

2), the output characteristic formula of the sensor

The output characteristic of a sensor is the relationship between the input and output of the sensor. For the sensor, the value of the input signal of the sensor is saved in the data text, and the input signal of the lower computer (ECU) is the value of the output voltage/frequency signal of the sensor, so the output characteristic formula of the sensor needs to be compared to the data in the data text to convert.

In general, what needs to be used is the static characteristic of the sensor, which refers to the change of the output of the sensor with the input when the input signal of the sensor is a steady-state signal or a slowly changing signal. The output characteristics of the sensor can be expressed by the nth power algebraic equation, namely:

y＝a ₀ +a ₁ x+a ₂ x ² +…+a _n x ⁿ

In the formula, x is the input of the sensor, such as temperature, pressure, etc.; the actual output signal of y is generally an electrical signal; a ₀ is the zero output; a ₁ is the linear sensitivity of the sensor, and a ₀ and a ₁ are known Parameters; a ₂ ,..., a _n are the undetermined constants of nonlinear items, the values of x and y are obtained from the actual measurement data, different x corresponds to different y values, with x as the abscissa and y as the ordinate, draw According to the characteristic curve, judge the functional relationship between y and x according to the curve, determine the highest order of x, then import the value into the mathematics software Matlab, and determine the specific values of a ₂ ,..., a _n according to its specific function function, and determine A function expression for the final actual output feature.

3) Determine the range of data values

The value ranges of the output characteristics of different sensors are different. In order to avoid invalid solutions in the process of signal value conversion, it is necessary to determine the value range of the data to make the solutions valid.

4) Data value

If the actual output signal y obtained in step 3) does not conform to the value range of the corresponding sensor, it will be discarded; if it does, the actual output signal y obtained at different times will be stored in the storage unit of the host computer and sent to The lower computer (ECU) outputs at the same time. Since the time interval for saving data in the TXT text is 1s, and there are at most two data within 1s, the time interval is taken as 500ms.

Taking the speed signal as an example, collect and save the speed signals at different times under the engine cold start condition in the host computer, and save the data in the second column of the table in Figure 2. The third line in the column is the data text of the pulse signal at time 2, and so on. During reconstruction, since the data types of different columns are defined when saving the data, selecting the data in the second column in Figure 2 will automatically determine the text type as the pulse signal , the upper computer automatically invokes the output characteristic formula of the static calibration of the speed sensor, and the solution obtained by putting the input into the formula is y, and the normal working range value of the speed sensor is [a, b], judge whether y exceeds [a, b], no If it is exceeded, it is regarded as an effective value, and if it is exceeded, it is discarded. In the upper computer that stores the value of y at different times, that is, the rotational speed value, it is sent to the lower computer (ECU) at a set interval as the input of its rotational speed signal.

As shown in Figure 4, it can be clearly seen that the change curve of the rotational speed signal in the figure well reconstructs the rotational speed signal in the experimental environment.

There are many application approaches of the present invention, and the above is only a preferred embodiment of the present invention. It should be pointed out that for those of ordinary skill in the art, some improvements can be made without departing from the principles of the present invention. These improvements should also be regarded as the protection scope of the present invention.

Claims (2)

1. the reconstructing method of an engine test environment lower sensor signal, it is characterised in that comprise the following steps:

1), upper computer reads the signal of each sensor and preserves by the form of setting; The sigtnal interval of described same sensor preserves;

2), upper computer resolves the signal of each sensor, it is determined that after each signal type, solves respective real output signal y by the output characteristic of sensor respectively:

Y=a₀+a₁x+a₂x²+��+a_nxⁿ

In formula, x is the input of sensor, a₀For zero-bit exports, a₁For the linear sensitivity of sensor, a₂,����,a_nFor the undetermined constant of non-linear item;

3), determining step 2) whether the respective real output signal y that obtains exceed the span of respective sensor, if exceeding, give up; If meeting, the input of lower computer when carrying out being stored as experiment with T interval time by each real output signal y.

2. the reconstructing method of engine test environment lower sensor signal according to claim 1, it is characterised in that: described interval time, T was less than the interval time that same sensor signal preserves.