KR19980050382A - Wheel speed simulator - Google Patents

Abstract

The present invention relates to a wheel speed simulator for an ABS simulator for simulating an anti-lock brake system (ABS) of an automobile, and more particularly to a wheel as a personal computer without adding a separate microprocessor. The present invention relates to a wheel speed simulator for effectively simulating speed. To this end, the present invention is a general-purpose computer that stores a control program for simulating and providing wheel speed, a clock divider connected to the general-purpose computer to divide a predetermined clock, and a clock divider connected to the general-purpose computer. An amplitude converter that receives a clock divided by the input signal and converts the amplitude thereof, an amplifier that receives a signal from the amplitude converter, amplifies the signal, receives an output signal of the amplifier, and removes a DC component included in the signal. A transformer having a value equal to the resistance of the sensor provided to the ABS ECU and inputting the same to the ABS simulator, and a clock generator for providing a predetermined clock frequency to the clock divider.

Description

Wheel speed simulator

The present invention relates to a wheel speed simulator for an ABS simulator for simulating an anti-lock brake system (ABS) of an automobile, and more particularly to a wheel as a personal computer without adding a separate microprocessor. The present invention relates to a wheel speed simulator for effectively simulating speed.

In general, a method of simulating (simulating) wheel speed (wheel speed) in an ABS simulator includes a method of manufacturing and using a wheel having a large inertia and a method using an electronic signal. The wheel speed signal generated by the rotation of the wheel is generally in the form of a sinusoidal wave, which is closely related to the type of the wheel speed sensor. The wheel speed sensor may be of an electromagnetic induction type, a Hall element, a magnetoresistive element, an optical type, and the like. The ABS sensor may be mainly an electromagnetic induction type sensor having excellent environmental resistance and low cost. The electromagnetic inductive sensor is composed of a ring-like ring and a sensor for detecting a magnetic field change. A sinusoidal wave is output by the number of teeth of the ring when the wheel rotates once. It is very important to accurately simulate the wheel speed because the frequency of the sine wave is converted to the wheel speed through the signal processing and used to perform ABS control by determining the lock or unlock of the wheel.

As a wheel speed simulator, a wheel with a large inertia is more similar to the actual conditions than an electronic signal. Therefore, a more accurate simulation can be performed, but the installation cost and time of the device are generally high. I use a lot of methods that use conventional signals. Electronic signals can be simulated using simple programs, which can be used to verify ABS control logic, analyze existing electronic control units (ECUs), and develop new ECUs.

The conventional wheel speed simulator disclosed in SAE paper 950758 is applied to a real-time ABS simulator, which will be described in more detail as follows.

That is, referring to FIG. 1, when the ABS simulator 1 transmits a signal command to the external microprocessor 2, the external microprocessor 2 generates a square pulse by inputting a command to the timer board 3 and generating a transformer ( In 4), the square pulse is converted into a sine wave and input to the ABS ECU 5. However, the wheel speed simulated by the wheel speed simulator has a disadvantage in that only frequency conversion is possible and signal amplitude is not controlled. Herein, reference numerals 6, 7, 8, 9, and 11 each represent an additional processor, a digital input / output unit, a digital / analog converter, a display device, and a logger constituting the ABS simulator.

Unlike the above case, according to the wheel speed simulator disclosed in SAE Paper 942297 by Sailor and Escers, both the frequency and amplitude signals can be changed so that these signals can be input to the ABS ECU. However, for this purpose, there is a disadvantage in that a computer is used instead of a personal computer. That is, as shown in Fig. 2, the wheel speed simulator by Sailor and E is a transformer which is connected to the ABS simulator 12 and is capable of changing both the amplitude and the frequency of the wheel speed signal and inputting it to the ABS ECU 14. The computer 13 will be included. Here, reference numerals 15, 16, and 17 are error monitors, solenoid valves, and interfaces constituting the ABS simulator.

However, the wheel speed simulator as described above cannot be driven in a general-purpose computer, and in order to simulate the wheel speed in the ABS simulator, a separate microprocessor has to be mounted. Therefore, this required a lot of hassle and cost.

The present invention was created to solve the above problems, and can be used to arbitrarily convert the output resistance using a general-purpose computer and a predetermined transformer without adding a separate microprocessor so that the frequency and amplitude can be controlled simultaneously. Its purpose is to provide a wheel speed simulator.

It is still another object of the present invention to provide a wheel speed simulator that enables the wheel speed signal to be controlled by a general-purpose computer to efficiently develop the ABS simulator and the logic analysis of the ABS ECU.

1 is a configuration diagram schematically showing a conventional wheel speed simulator,

2 is a schematic view showing another conventional wheel speed simulator;

3 is a block diagram illustrating a wheel speed simulator according to the present invention;

4 is a graph showing the safe operation area and the failure operation area of the wheel speed simulator according to the present invention;

5 is a graph showing an output signal of an amplifier and a transformer of the wheel speed simulator of the present invention;

6 to 12 are graphs showing the simulation experiment results of the wheel speed simulator of the present invention.

* Explanation of symbols for main parts of the drawings

10: general purpose computer 20: clock divider

30 amplitude converter 40 amplifier

50: transformer 60: clock generator

100: ABS simulator 200: ABS ECU

Wheel speed simulator according to the present invention to achieve the above object,

A wheel speed simulator for providing a predetermined wheel speed to an ABS simulator that simulates an ABS ECU,

A general purpose computer storing a control program for providing the wheel speed, a clock divider connected to the general purpose computer to divide a predetermined clock, and a clock divided from the clock divider connected to the general purpose computer An amplitude converter for converting the amplitude, an amplifier for receiving the signal from the amplitude converter and amplifying the signal, a sensor for receiving the output signal of the amplifier and removing the DC component included in the signal to provide the ABS ECU It is characterized in that it comprises a transformer having a value equal to the resistance of and inputting it to the ABS simulator, and a clock generator providing a predetermined clock frequency to the clock divider.

In a preferred embodiment of the present invention, a sinusoidal converter may be further included between the amplifier and the transformer to convert a predetermined square clock signal into a sine wave.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the wheel speed simulator according to the present invention.

The wheel speed simulator according to the present invention is capable of arbitrarily converting the output resistance using a general-purpose computer and a predetermined transformer without controlling an additional microprocessor, and simultaneously controlling the frequency and amplitude. As described above, a general-purpose computer 10 storing a control program for providing the wheel speed, a clock divider 20 connected to the general-purpose computer 10 to divide a predetermined clock, and the general-purpose computer ( An amplitude converter 30 that is connected to 10 and receives a clock divided by the clock divider 20 and converts an amplitude thereof, and an amplifier 40 that receives a signal from the amplitude converter 30 and amplifies the signal. ), And the output signal of the amplifier 40 is received to remove the direct current component included in the signal to the same value as the resistance of the sensor provided to the ABS ECU 100 So that by this, it is achieved by a clock generator 60 to provide a predetermined fixed clock frequency to the transformer 50, and the clock frequency divider 20 for input to the ABS simulator 200. In addition, the present invention is interposed between the amplifier 40 and the transformer 50, as shown by the dotted line in Figure 3 receives the output signal of the amplifier, for example, a square clock signal is received as a predetermined sine wave waveform After the conversion may include a sine wave converter 45 input to the transformer 50. Here, the clock generator 60 is preferably a clock generator which generates 2 MHz, the divider 20 preferably comprises a divider IC 8253, and the amplitude converter 30 preferably has an 8-bit digital to analog converter. Perform amplitude conversion using. The amplifier 40 preferably converts a voltage value of 0-12 volts into approximately 50 mV units.

Reference numerals 12 and 14 denote the addresses and data output from the general purpose computer 10 and input to the clock divider 20 and the amplitude converter 30, respectively. Reference numeral 16 denotes a brake switch (not shown). Indicates a brake relay for activation.

Referring to the operation and operation of the wheel speed simulator according to the present invention configured as described above are as follows.

First, prior to explaining the specific operation and operation of the wheel speed simulator of the present invention, in order to understand the wheel speed simulator of the present invention in more detail, a method for measuring the wheel speed in the ABS ECU mounted on the actual vehicle and the ABS Describes the diagnostics function of the ECU.

In a wheel speed sensor that is applied to a wheel of an actual vehicle and provides a wheel speed signal to the ABS ECU 200, the gear-shaped ring is ferromagnetic and the sensor is made of a magnet and a coil. When the ring mounted on the wheel rotates, magnetic flux change occurs between the sensor and the ring, and induction electromotive force is generated on the coil of the sensor. The induced electromotive force is in the form of a sine wave, and if the number of teeth of the ring is N, N sinusoids are generated in one revolution. The magnitude of the sine wave is inversely proportional to the air gap between the sensor and the ring and is proportional to the rotational speed of the ring. The frequency of the sine wave is independent of the air gap and is proportional to the rotational speed of the ring. Since air gaps and number of teeth vary from vehicle to vehicle, the amplitude and frequency of sine waves also vary from vehicle to vehicle. The sine wave output from the four wheel speed sensors is converted into wheel speed in the ABS ECU 200. The input signal is passed through a lowpass filter to remove noise and then converted to square pulses through a comparator. The time interval of the square pulse is calculated by the rotation frequency and the wheel speed, which is the basic variable of ABS control, is calculated.

In general, the ABS ECU 200 includes two microprocessors, and has a built-in diagnostic function in addition to the ABS control function. The failure of ABS directly affects brake performance and is directly connected to the driver's life, so the diagnostic function is one of the important functions of the ABS ECU 200. In order to analyze the ABS ECU 200 using the wheel speed simulator, the diagnosis logic must pass through the diagnostic function, which is essential for the development of the wheel speed simulator. Basic diagnostic functions include wiring short test, sensor short test, motor short test, battery voltage test and sensor resistance test. The air gap defect and wheel defect test of the wheel speed sensor measured during operation of the vehicle are included. Diagnosis is mainly performed at the start of the vehicle and continuously monitors the status of ABS at regular intervals. If a problem occurs in the diagnosis, a warning light is turned on and the operation of the ABS is stopped.

4 shows the frequency and amplitude of the wheel speed signal. The area that passed the diagnosis is marked as SAFE, and the area that does not pass is denoted as FAIL. When the vehicle starts, the ABS ECU 200 measures the frequency when the wheel starts to rotate after performing the basic diagnosis and measures the motor voltage when it reaches 30 Hz. Tolerance of air gap is about 1mm and set the voltage value based on the allowable range of air gap. If the voltage value measured at 30Hz is higher or lower than the reference value, it is judged that the air gap is too small or too large to diagnose the diagnostic error signal. Output If the voltage value measured at 30 Hz is within the reference range, the air gap is determined by linearly calculating the point where the frequency and amplitude are zero and the frequency and amplitude points measured at 30 Hz. Based on this slope, there is a tolerance considering noise based on the reference slope to determine whether the air gap is defective by measuring frequency and amplitude according to the rotation speed. In FIG. 4, the reference slope and the tolerance region are denoted as SAFE. When the air gap is increased, the frequency and amplitude relationship moves vertically downward from the reference slope to the failure region.

Therefore, the wheel speed simulator must pass the ABS ECU to interpret the ABS ECU 200, and in order to be applied to the ABS simulator, the number of instructions for controlling the wheel speed must be small and controllable by a general purpose computer. That is, the wheel speed simulator must have the following conditions.

First, the input resistance of the wheel speed simulator should be equal to the input resistance of the actual wheel speed sensor. The input resistance of the wheel speed sensor is usually about 1 kilo ohm, so the resistance of the sensor is checked by the ABS ECU. Therefore, the input resistance of the wheel speed simulator should be equal to the resistance of the sensor.

Second, the amplitude and frequency must be controllable, and the frequency and amplitude must be maintained in a linear relationship because they are related to the defects of the sensor and air gap.

Third, the number of commands required to generate the wheel speed signal should be small. As the number of control commands for the wheel speed signal increases, the operation time of the ABS simulator should be minimized.

Fourth, four wheel speeds should be output and each wheel speed should be independent.

Fifth, the frequency must be controlled regardless of the time the software in the ABS simulator is running.

Sixth, the microprocessor should not be installed in addition to the general purpose computer of the ABS simulator. It is desirable to control signals using a general purpose computer for the development cost and simplicity of the ABS simulator.

3 shows a wheel speed simulator of the present invention that satisfies the above conditions, wherein the general purpose computer 10 of the wheel speed simulator is a general-purpose computer model of 286 or more, and controls signals using the C language. The clock frequency generated by the clock generator 60 is 2 MHz, and this clock frequency signal is input to the divider 20 and controlled. The divider 20 receives the clock frequency signal and generates a square pulse accordingly. The frequency of the wheel speed signal is 1 KHz or less, which is calculated by considering the tire radius of the vehicle, the number of teeth of the ring, and the rotation speed. The square pulses divided by the clock divider 20 and outputted have only frequency characteristics, which are amplitude-converted by an 8-bit digital analog (DA) converter of the amplitude converter 30. The signal output from the DA converter of the amplitude converter 30 has a frequency characteristic of 0-1KHz and has an amplitude of 0-5 volts. The signal output from the amplitude converter 30 is input to the amplifier 40, amplified to 0-11 volts and input to the transformer 50. The transformer 50 serves to maintain the input resistance at 1 kilo ohm, which is the resistance value of the vehicle sensor. Here, the sine wave converter 45 may be interposed between the amplifier 40 and the transformer 50 so that the signal output from the amplifier 40 may be more preferably converted than in the transformer 50.

FIG. 5 is a graph showing an output signal of the amplifier 40 and an output signal of the transformer 50 when simulating the wheel speed simulator of the present invention operating at 80 km / h. As shown in FIG. The output signal of takes the form of a square signal of 0-10 volts, and the output signal of the transformer 50 changes to an alternating current component without a direct current component and takes the form present in the range of -10-10 volts. If the sinusoidal wave converter 45 shown in dashed line in FIG. 3 is interposed between the amplifier 40 and the transformer 50, the direct current component can be more reliably removed. The signal of the transformer 50, which is the final signal input to the ABS ECU 200, is not in the form of a sine wave, but is converted into a square pulse form during signal processing in the ABS ECU 200. It is recognized the same as sine wave.

Since the wheel speed simulator of the present invention as described above uses the transformer 50, the output resistance can be arbitrarily converted, and the frequency and amplitude can be controlled simultaneously. In addition, the general-purpose computer 10 can linearly program and output a relationship between frequency and amplitude. In addition, since the wheel speed simulator of the present invention includes an amplitude converter 30 including a divider 20 and a digital / analog converter, the wheel speed simulator can more effectively simulate the wheel speed than using only the digital / analog converter. .

In the present invention, since two commands for controlling the frequency divider 20 and one command for controlling the amplitude converter 30 are input to output a speed of 80 km / h, a total of 12 are used when four wheels are used. Command. In order to maintain the speed of 80 km / h, no additional instruction is required, and every time the speed is converted, 12 commands are inputted to the general purpose computer 10. Therefore, according to the present invention, when performing the wheel speed simulation using a conventional digital / analog converter only, at least four to seven commands per wheel should be input to output a sine wave of one cycle. To solve the problem of having to input 28 commands at regular intervals in order to input 28 commands and maintain a speed of 80 km / h.

In addition, when the wheel speed is simulated using only a conventional analog / digital converter in order to increase the speed to a constant acceleration, the command should be input while calculating a predetermined time interval. Just type. In particular, when all four wheel speeds are different, the calculation process and the input time interval are very complicated in the related art, but the present invention only needs to input 12 commands regardless of the time interval.

In the wheel speed simulator according to the present invention, when the general-purpose computer 10 is a 386-class personal computer, it takes about 10 microseconds to input a command, and when it is a 586-class personal computer, it is 1 microsecond (usec). It takes time. When the general-purpose computer 10 of the present invention is a 586-class personal computer, even if the wheel speed of one wheel is converted 100 times per second, it takes about 400 microseconds, which is 1 millisecond (1 msec). Since it is below, the time required for the wheel speed simulator is sufficient to perform the ABS simulation. However, in the case of using only a conventional digital-to-analog converter, the process of performing input time intervals and instructions is complicated, and thus, a microprocessor other than a general-purpose computer has to be installed. Therefore, the wheel speed simulator of the present invention has a great advantage of having a small number of input commands and simulating the wheel speed regardless of the input time interval.

6 to 12 are shown with reference to the experimental results of the wheel speed simulation by the wheel speed simulator according to the present invention described so far. A hydraulic control unit (HCU) and related wiring were used for the experiment of the wheel speed simulation by the wheel speed simulator of the present invention, which is a solenoid valve having four solenoid valves and four flow control valves. Flow type was used and wiring was configured including diagnosis and motor relay. As a general-purpose computer 10, a 386-class personal computer was used, and a DC power supply of 13V, 3A, and 13V, 30A was used as a power supply. In addition, a light bulb was connected to the pin that outputs the ABS warning lamp of the ABS ECU to check for abnormalities, and each signal was measured using an oscilloscope for the warning lamp, the motor relay, four wheel speeds, and the solenoid input unit.

6 shows that the motor is driven at 7 km / h as the wheel speed is increased, and FIG. 6 (A) shows that the four wheel speeds are increased by 0.5 g (g = 9.81 m / sec ² ). 6 (B) shows the change of the input voltage of the motor in the above case. And, Figure 7 shows the result when the frequency is maintained at a wheel speed of 80km / h and the amplitude is reduced, Figure 7 (A) shows the wheel speed in this case, Figure 7 (B) is It shows voltage change of warning lamp in case. 8 shows signal changes when the wheel speed is rapidly lowered from 80 km / h to 2 km / h. FIG. 8 (A) shows the case of the wheel speed, and FIG. 8 (B) shows the voltage change of the warning light. It is shown. 9A to 9D show speed signals of the front wheels and the rear wheels and operating states of the solenoid valves of the front wheels and the rear wheels on a high friction road surface (for example, an asphalt road). 10 (A) to (D) show the speed change of the front wheel and the rear wheel and the operating states of the solenoid valves of the front wheel and the rear wheel on the medium friction road surface, respectively, and the deceleration of the front wheel is the same as that of the high friction road surface. This is the case where the rear wheel is also locked by increasing the deceleration. 11 (A) to (C) show the speed signals of the wheels and the operating states of the solenoid valves of the front and rear wheels when the four wheels are decelerated to 4.5g on the low friction road surface. 12 (A) to (C) show the speed signals of the wheels and the operating states of the solenoid valves of the front and rear wheels when the four wheels are decelerated to 5.8g on the low friction road surface.

As described above, the wheel speed simulator according to the present invention can arbitrarily convert the resistance of the output signal using a general-purpose computer and a predetermined transformer without adding a separate microprocessor, and can simultaneously control the frequency and amplitude. This provides the advantage of making the simulation of ABS ECUs effective. In addition, the present invention provides the advantages of achieving a simplification of the wheel speed simulator and of achieving a lower cost.

Claims (11)

A wheel speed simulator for providing a predetermined wheel speed to an ABS simulator that simulates an ABS ECU of a vehicle, the wheel speed simulator comprising: a general-purpose computer storing a control program for providing the wheel speed, and a predetermined clock connected to the general-purpose computer. A clock divider for dividing, an amplitude converter connected to the general-purpose computer and receiving a clock divided from the clock divider and converting an amplitude thereof, an amplifier for receiving a signal from the amplitude converter and amplifying the signal; A transformer that receives the output signal of the amplifier and removes the DC component included in the signal to have the same value as the resistance of the sensor provided to the ABS ECU and inputs it to the ABS simulator, and a predetermined predetermined value for the clock divider. Includes a clock generator that provides the clock frequency Wheel speed simulator. 4. The wheel speed simulator of claim 1 wherein the clock generator generates a clock frequency of 2 MHz. 2. The wheel speed simulator as claimed in claim 1, wherein the divider includes an IC 8253. 2. The wheel speed simulator of claim 1 wherein the amplitude converter comprises an 8-bit digital / analog converter. The wheel speed simulator as claimed in claim 1, wherein the amplifier amplifies and converts a voltage value of 0-12 volts in approximately 50 mV units. The wheel speed simulator as claimed in claim 1, wherein the general-purpose computer is a personal computer of class 286 or higher. 7. The wheel speed simulator according to any one of claims 1 to 6, wherein the signal resistance value output from the wheel speed simulator is the same as the signal resistance value output from the wheel speed sensor of the actual vehicle. 5. The wheel speed simulator as claimed in claim 4, wherein the signal output from the digital / analog converter of the amplitude converter has a frequency characteristic of 0-1 kHz and an amplitude characteristic of 0-5 volts. The wheel speed simulator as claimed in claim 5, wherein the amplifier amplifies the output signal of the amplitude converter to 0-11 volts and outputs the amplified output signal. 8. The wheel speed simulator of claim 7, wherein the transformer maintains the resistance of the output signal at approximately 1 kiloohm. 6. The apparatus of any one of claims 1 to 5, further comprising a sine wave converter interposed between the amplifier and the transformer to convert an output signal of the amplifier into a predetermined sine wave signal and input the same to the transformer. Wheel speed simulator.