JPH03286340A - Diagnostic device for cpu abnormality - Google Patents

Abstract

PURPOSE:To eliminate the difference caused by a reading error, etc., of the input information and to improve the diagnostic accuracy by diagnosing the abnormality with comparison carried out between the computing results of two CPUs obtained based on the exactly same input information. CONSTITUTION:An input information transmission means sends the input information read by a CPU I to a CPU II. A comparison means compares the input information sent by the input information transmission means and read by the CPU I with the input information read by the CPU II. When the coincidence is obtained between both input information, an arithmetic execution means performs an operation based on the input information sent to the CPU II from the input information transmission means. Then the computing result of the CPU I is compared with that of the CPU II. If no coincidence is obtained between both computing results, a decision means decides the occurrence of the abnormality. Thus the computing results of both CPUs are compared with each other based on the common input information that is completely free from any reading error for diagnosis of the abnormality. As a result, the diagnostic accuracy is improved for the CPU abnormality.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention provides a CPU that is equipped with two CPUs and that diagnoses an abnormality when the calculation results of the two CPUs differ for common input information. This invention relates to improvement of an abnormality diagnosis device.

<Prior Art> In a four-wheel steering vehicle, when steering the front wheels, the rear wheels are steered in the same direction or in the opposite direction to the front wheel steering direction, and the steering direction and steering angle of the rear wheels are determined based on various driving information of the vehicle. The rear wheels are steered by controlling the opening degree of a flow control valve installed in a rear wheel drive motor or a hydraulic circuit (Japanese Utility Model Publication No. 158509/1988).

Conventionally, such rear wheel steering control uses two main and sub CPUs 2 to calculate a control amount based on common input information, as shown in FIG. It is read and compared with the result calculated by the sub CPU 2 itself, and if the two match, the calculation result is output as is as a rear wheel steering control signal, but if they differ, it is determined that one of the CPUs is abnormal (runaway). Then, the sub CPU 2 outputs a fail-safe signal to the output stop circuit 3 to stop outputting the rear wheel steering control signal.

<Problems to be Solved by the Invention> However, in such a conventional CPU abnormality diagnosis device, the same input signal is input to the two CPUs, but the output result may vary due to an error in reading the input information of both. Even under normal conditions, when comparing calculation results based on input information with different input timings due to differences in input timing or time delays before outputting the output signal, the two values may not match even under normal conditions and a failsafe is activated. There were times when I ended up doing this. Therefore, for example, when comparing the rear wheel control signal output as an 8-bit signal before outputting it, only the upper 4 to 6 bits are compared to match.

Although discrepancies were detected, the diagnostic accuracy was naturally inferior.

The present invention has been made in view of such conventional problems, and an object of the present invention is to provide an abnormality diagnosis device that can perform abnormality diagnosis of a CPU with high accuracy.

<Means for Solving the Problems> Therefore, as shown in FIG. 1, the present invention includes two CPUs, and input information read by one CPU is transferred to the other CPU.
an input information transmitting means for transmitting to U; a comparing means for comparing the input information transmitted by the input information transmitting means with the input information read by the other CPU; calculation execution means for causing the other CPU to perform calculations based on the input information transmitted by the input information transmission means when the two input information substantially match;
determining means for comparing the calculation result calculated by the other CPU by the calculation execution means with the calculation result calculated by one CPU using common input information, and diagnosing that there is an abnormality when the two do not match; Prepare and configure.

<Operation> The input information transmission means is connected to one of the CPUs (for example, the main CPU
The input information read by the CPU (PU) is transferred to the other CPU (sub CPU).
U).

The comparison means compares the input information read by one CPU transmitted by the input information transmission means and the other CPU.
Compare the input information read by the PU.

If the two substantially match, the calculation execution means causes the other CPU to execute the calculation based on the input information transmitted from the input information transmission means.

The calculation result by the other CPU is compared with the calculation result by one CPU, and if the two do not match, the determining means determines that there is an abnormality.

According to this, the abnormality diagnosis is performed by comparing the calculation results of the two CPUs based on completely common input information with no reading errors, so the diagnosis accuracy is greatly improved.

<Example> Embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows the configuration of an embodiment in which the present invention is applied to a rear wheel steering control device for a four-wheel steering vehicle, similar to the conventional example.

In the figure, main CPU Ull and sub CPU12
includes various input information for rear wheel control (vehicle speed, front wheel steering angle,
Rudder angular speed, rudder angular acceleration, and rear wheel rudder angle.

signals such as steering angular velocity) are input.

The sub CPU 12 has D, P, RAM (dual port RAM) 12A;
Communication line 1 with main CPU II via 2A
Data is exchanged through the CPU 12, and in particular, the input information read by the CPU II at the time of an abnormal # disconnection and the display of the completion of calculation based on the input information are displayed through the CPU 12, the P
, are transmitted to and stored in the RAM 12A.

The output (calculation result) of the CPU II is read into the CPU 12 and monitored, and when an abnormality is diagnosed, a fail-safe signal is output to the output stop circuit 14 to stop the output, as in the conventional case.

The routine executed by the main CPU II and the sub CPU 12 will be described below with reference to FIGS. 3 and 4.

In Figure 3, which shows the main CPU II routine,
In step 1 (denoted as S in the figure), an input signal is read (data calculation).

In step 2, the input information read in step 1 is sent to the CPU 12 and P via the communication line 13.

Transmit to RAM 12A.

When the transmission is completed, the process advances to step 3 and the input transmission flag is set to 1.

In step 4, the control a value for rear wheel steering, specifically the polarity and current of the drive motor, are calculated.

When the calculation is completed, the process proceeds to step 5, where a control mtlX flow corresponding to the calculation result is output to the drive motor.

In step 6, the output transmission flag is set to l.

In FIG. 4 showing the control routine of the sub CPU 12, in step 11 an input signal is read.

In step 12, it is determined whether the input transmission flag is set to 1 in the main CPU II, and after waiting for the input transmission flag to be set, the process proceeds to step 13.

In step 13, the input transmission flag is reset to zero.

In step 14, input information from the main CPU II stored in the D, P, and RAM 12A is transferred to the sub CPU 12.
Compare and check with the input information read in.

If the two values differ beyond the error range, the process proceeds to step 15 to output a failsafe signal, but if they match within the error range, the process proceeds to step 16.

In step 16, the sub CPU 12 calculates the rear wheel control m value based on the input information read by the D, P, and RAM 12A, that is, the input information read by the main CPU Ull.

In step 17, it is determined whether or not the output transmission flag is set to 1 in the main CPU II, and the process waits for the output transmission flag to be set before proceeding to step 18.

In step 18, the output transmission flag is reset to zero.

In step 19, the output value by the main CPU Ull (the calculation result in step 4) is compared with the calculation result in step 16 by the sub CPU 12.

If the two values match, it is determined to be normal and this routine ends; however, if they do not match, it is diagnosed as abnormal and proceeds to step 15, where a failsafe signal is output and a control signal is output. stop.

In this way, the main CP Ull and the sub CP
Since abnormality diagnosis is performed by comparing the calculation results based on the same input information with U12, highly accurate diagnosis can be performed by eliminating differences due to input information reading errors, output delays, etc.

In addition, step 2 and communication line 13, P, RAM 12
A constitutes an input information transmission means, the function of step 14 constitutes a comparison means, the function of step 16 constitutes an arithmetic execution means, and the function of one step constitutes a determination means.

<Effects of the Invention> As explained above, according to the present invention, the abnormality diagnosis is performed by comparing the results calculated by two CPUs based on exactly the same input information, so that errors in reading input information and Highly accurate diagnosis can be performed by eliminating differences due to output delays, etc., and can meet the demands for high reliability in vehicle rear wheel steering control, etc.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of the present invention, and FIG. 2 is a block diagram showing the configuration of the present invention.
3 and 4 are flowcharts showing a routine by the main CPU and sub-CPtJ of the embodiment of the present invention, and FIG. 5 is a diagram showing a conventional example. be.

Claims (1)

[Claims] An input information transmission means comprising two CPUs and transmitting input information read by one CPU to the other CPU, input information transmitted by the input information transmission means, and input information read by the other CPU by itself. a computation means for causing the other CPU to perform a computation based on the input information transmitted by the input information transmitting means when the two pieces of input information compared by the comparator substantially match; Comparing the calculation result calculated by the other CPU by the calculation execution means with the calculation result calculated by one CPU using common input information, and determining means for diagnosing that there is an abnormality when the two do not match. 1. A CPU abnormality diagnosis device characterized in that the CPU abnormality diagnosis device is configured as follows.