JPH06298105A - Rear wheel steering device control system - Google Patents

Abstract

PURPOSE:To assure and stabilize the control by dividing a control system into a main system and a sub-system which are independent of each other, conducting calculation for rear wheel steering to output control signals, monitoring their respective power supply sections, and adopting only the control signal of a normal system in the occurrence of abnormality for fail-safe control in a rear wheel steering device control system for a vehicle and the like. CONSTITUTION:A main power supply 11 and sub-power supply 15 are connected to each other by the two lines from a battery 10 in parallel, and the states of the power supply sections 11 and 15 of their respective systems are monitored by a main CPU 12 and a sub-CPU 16 respectively. The CPUs 12 and 16 output judgment flags, conduct calculation based on the signal from a sensor 17 for rear wheel steering, and output rear wheel steering signals. These judgment flags and steering signals are input in a comparison section 13 to judge whether the state of each of the power supply sections 11 and 15 are normal or abnormal. If it is abnormal, usual control is suspended, and fail-safe control is conducted so that the rear wheels return to the neutral position where they are not steered.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a so-called 4WS (four-wheel steering) system for controlling front-wheel steering as well as rear-wheel steering in a vehicle or the like.

[0002]

2. Description of the Related Art Conventionally, a system in which a rear wheel is steered by an electric motor or the like has been proposed in Japanese Patent Application Laid-Open No. 61-146681 in order to improve the running performance of a vehicle. In this method, for example, in order to prevent a phenomenon in which the rear wheels are steered arbitrarily due to a system abnormality, it has been proposed to establish sufficient reliability in the motor drive system for the rear wheel steering,
Japanese Unexamined Patent Publication No. 2-249762 discloses a double CPU system using two motor control CPUs (arithmetic units) as a fail-safe for that purpose. This is the remaining CP even if one CPU control system has some trouble.
Since it can be controlled correctly by the U control system, it is highly safe.

[0003]

However, in the proposed double CPU system, since there is only one power supply for driving the two-system control system, if an abnormality or failure occurs in the power supply system, both control systems are controlled. It went down with the system,
There is a problem in that the vehicle may stop at an abnormal steering position during traveling and the vehicle traveling may become unstable. In order to avoid this, it is conceivable to add a mechanism for returning the rear wheel to the neutral position with a mechanical spring or the like, but this method has a problem that it becomes a large-scale and complicated device. Therefore, an object of the present invention is to ensure more reliable control without changing the control system on a large scale.

[0004]

In order to solve the above problems, the structure of the present invention controls the rear wheel steering drive unit by determining the driving direction and driving torque of the rear wheel steering according to the steering of the steering wheel. In a control system for a rear wheel steering system in which a control device is installed independently of a main system and a sub system, a main power supply installed in the main system and a sub power supply installed in the sub system have independent power supply units. And a power supply monitoring unit that monitors the power supply units of the other systems by the main processing unit of the main system and the sub processing unit of the sub system.
By the power supply monitoring means, when any one of the power supply portions is abnormal, a fail-safe means for controlling rear wheel steering to return to a neutral position, and the main arithmetic operation portion and the sub arithmetic operation portion independently calculate A control instruction means for outputting a control instruction, a control comparison means for comparing the two control instructions, and a rear wheel steering drive means for receiving the final instruction determined by the control comparison means and steering the rear wheels. It is characterized by having.

[0005]

The control system is installed independently from the power supply unit, and performs the calculation for the rear wheel steering and outputs the control signal. Control is performed based on these two indicated values. In addition, monitoring each other's power supply unit, if there is an abnormality, it is transmitted to the control signal comparison unit and only the control signal of the normal system is adopted, normal control is interrupted and the rear wheel is set to the neutral position in the non-steering state. Perform fail-safe control to return. For CPU-related abnormalities, the conventional fail-safe is applied.

[0006]

As an effect of the present invention, the rear-wheel steering control is abnormal even in the case of an abnormality from the power supply system by the mutual power supply monitoring of the two-system control by the two-system power supply, compared with the two-system control of the single power supply. You can guarantee more safety without becoming.
When the original battery is abnormal, the entire vehicle is also abnormal and the abnormality of the steering device is not determined. Therefore, if it is fail-safe for the control device side from the abnormality of the drive power supply line, sufficiently reliable control can be guaranteed.

[0007]

EXAMPLES The present invention will be described below based on specific examples. FIG. 1 shows a control system of a rear wheel steering system in which a motor 18 in a rear wheel steering mechanism schematically shown in FIG. 2 is controlled by an instruction from an ECU (electronic circuit control unit) 20 in accordance with front wheel steering. It is shown in a block diagram. The vehicle battery 10 is connected to the main power supply 11 and the sub power supply 15 by two lines, and the main power supply 11 is connected to the main CPU.
Electric power is supplied to the (main calculation unit) 12, the comparison unit 13, and the motor drive unit 14, while the sub power supply unit 15 supplies the sub CP.
Electric power is supplied to the U (sub-calculation unit) 16, the comparison unit 13, and the motor driving unit 14. Signals from various sensors of the sensor unit 17 are similarly input to both CPUs.
In addition, each CPU has power supply units 11 and 15 of its control system.
Are connected to each other to monitor the state of and detect the abnormality of the power supply unit. The comparison section receives various control signals from both CPUs and sends signals to the motor drive means 14 based on them. The motor driving means 14 is a motor 1 for steering the rear wheels based on the control signal.
8 is driven by the electric power of the main power source 11 or the sub power source 15 to perform rear wheel steering. As the sensors used for steering the rear wheels, in addition to the steering sensor 21, the vehicle speed sensor 22 and the motor position sensor 23 shown in FIG. 2, a wheel speed sensor, a yaw rate sensor, a lateral G sensor (not shown) for improving control depending on the purpose. Sensors etc. are connected.

The two CPUs 12 and 16 mutually check the power source section of the other CPU and output a determination flag.
In addition, the signals of the respective sensors required for steering the rear wheels are input and calculation is performed, and the steering signals for the rear wheels are output. The comparison unit that has received the steering signal sends a control signal to the motor driving means based on the result of the determination based on the result of the determination based on the determination flag if the determination is normal.

FIG. 3 shows a flowchart of this processing relating to the rear wheel steering control in both arithmetic units. The routines of both CPUs have the same flow, and the only difference is that the power supply unit to be monitored is the power supply unit of the other party. One time of this routine means one time of rear wheel steering control, and since the steering control is normally continuously performed, the whole program is constructed so that this routine is performed every 5 msec, for example. Since the contents are the same, the routine of the main CPU 12 will be described as a representative.

In the flowchart on the main CPU side of FIG. 3, in step 200, the main CPU 12 first takes in the voltage of the sub power source through A / D conversion. Next step 20
In 2, the signal from each sensor is also taken in through A / D conversion. Next, in step 204, it is judged whether or not there is an abnormality in the sub power source, and if normal, the rear wheel steering angle θr is calculated based on each signal value in step 206, and the motor control in step 212 is executed. If there is an abnormality in the determination in step 204, the sub-voltage abnormality flag is output in step 208, θr is subtracted in step 210, and θr is reduced each time this loop is passed.
Is subtracted until 0 becomes 0, and motor control is executed in step 212. On the sub CPU side, step 104 determines whether or not the other party's main power supply is abnormal. These routines are repeated to control the rear wheel steering.

As a result of the above determination, the output is output to the motor drive means in the comparison section by comparing the main and sub signals with the result of the power supply section check. The operation of this comparison unit will be described with reference to FIG. There are two control signals output from both CPUs, a direction signal and a duty signal as a power control signal. Each of these direction signals together with the fail signal output from the control device of the other OR circuit 4
3 and 44. Only when the results of the OR circuits 43 and 44 coincide with each other in the AND circuit 45, the result is output to the motor driving means. In other words, the direction signal improves safety by connecting two systems of signals in parallel. Further, the two power control signals are input to the AND circuits 40 and 41 together with the fail signals output from their own CPUs, and when one of the power supplies is abnormal, the power control of the normal system among the outputs of these AND circuits is performed. The signal is selected by the OR circuit 42 and output to the phase switching logic 50 which is a part of the motor driving means 14. Further, since both fail signals are Lo in the normal state, both fail signals connected to the NOR circuit 46 become Hi in the NOR circuit 46, and the AND circuit 47.
Then, the power control signal on the main side is output to the phase switching logic 50.

For example, if there is an abnormality in the sub power supply 15 system, the main CPU 12 detects the abnormality and sets the Vs fail signal to Hi. Then OR receiving the direction signal
The circuit 43 forces the direction signal from the sub CPU 16 to H level.
i. Therefore, the AND circuit 45 causes the main CPU 12
Only the direction signal of is output to the motor drive means. The direction signal at the time of this abnormality is a routine for returning the steering to the neutral position, as described in the flowchart of FIG. On the contrary, even when the main power supply 11 becomes abnormal, the signal of the abnormal control system is suppressed by the same logic, and the steering is returned to the neutral position.

As described above, in the two-system control system, the power supply section is also independently set to the two system, and each computing section (CP
(U) can establish fail-safe against abnormalities in the power supply system by monitoring and controlling the power supply of the other party, and if an abnormality occurs in the power supply part in a single system, the rear wheels will be fixed in a non-neutral position. The problem is avoided. Therefore, safety can be improved without changing the rear wheel steering mechanism.

[Brief description of drawings]

FIG. 1 is a block diagram of a rear wheel steering system control system.

FIG. 2 is a schematic system configuration diagram of a rear wheel steering device.

FIG. 3 is a control flowchart of each system.

FIG. 4 is a detailed configuration diagram of a comparison unit of the control device.

[Explanation of symbols]

11 Main Power Supply (Power Supply Means) 12 Main CPU (Main Computing Unit, Control Instructing Means) 13 Comparing Unit (Control Comparison Means) 14 Motor Driving Means (Rear Wheel Steering Driving Means, Rear Wheel Steering Driving Means) 15 Sub Power Supply (Power) Supply means) 16 Sub CPU (sub-calculation section, control instruction means) 17 Sensor section 18 Motor (rear wheel steering drive means) 20 ECU (electronic circuit control device, main / sub control system) 21 Steering sensor 22 Vehicle speed sensor 23 Motor Position sensor 40, 41, 45, 47 AND circuit (control comparing means) 43, 44, 42 OR circuit (control comparing means) 46 NOR circuit (control comparing means) 50 Phase switching logic (motor driving means) Steps 104, 204 ... … Power supply monitoring means Steps 110 and 210 …… Fail-safe means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshihiko Tsuzuki, 1-1, Showa-cho, Kariya city, Aichi prefecture

Claims (1)

[Claims] 1. A rear wheel steering system in which a control device for controlling a rear wheel steering drive unit by determining a driving direction and a driving torque of the rear wheel steering according to steering of a steering wheel is installed independently in a main system and a sub system. In a control system of the apparatus, a power supply unit including a power supply unit independent of a main power supply installed in the main system and a sub power supply installed in the sub system; a main operation unit of the main system; A power supply monitoring unit that monitors the power supply units of the other systems by the sub-computing unit of the system, and a control that returns the rear wheel steering to the neutral position when one of the power supply units is abnormal by the power supply monitoring unit. A fail safe means, a control instruction means for independently calculating each of the main arithmetic unit and the sub arithmetic unit and outputting a control instruction, a control comparing means for comparing the two control instructions, and the control comparing means. The control system of the rear wheel steering apparatus characterized by having a wheel steering drive means after performing rear wheel steering in undergoing final indication determined.