JPH0796907B2 - Load drive control system fail detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a micro controller as an electronic control system such as an auxiliary steering control system or an active suspension control system for auxiliary steering at least one of front wheels and rear wheels when steering front wheels. The present invention relates to a load drive control system failure detection device applied to various control systems including a computer and a load drive control circuit.

(Prior Art) As a rear wheel steering control system to which a load drive control system failure detection device is applied, for example, there is a system proposed by the applicant of the present application in Japanese Patent Application No. 63-165932.

This rear-wheel steering control system determines a target rear-wheel steering angle at which optimum vehicle dynamic characteristics are obtained based on the front-wheel steering angle and vehicle speed during turning steering, and the rear wheel is rotated in-phase or in-phase with the front wheel by a hydraulic actuator. The rudder control is performed to improve steering stability and steering responsiveness as compared with, for example, a front wheel steering vehicle (2WS vehicle).

(Problems to be Solved by the Invention) In such a rear wheel steering control system, a drive current based on a drive current command signal calculated by a microcomputer of the rear wheel steering control unit is applied from a solenoid drive circuit to an electromagnetic valve. In this electromagnetic valve, the input hydraulic pressure is adjusted to the control hydraulic pressure, and this control hydraulic pressure is supplied to the hydraulic actuator to control the steering of the rear wheels. Also, it is necessary to monitor whether the solenoid drive circuit is operating normally.

Therefore, according to the general method that has been performed from the past,
As shown in FIG. 8, fail monitoring means is provided in each of the microcomputer and the solenoid drive circuit.

That is, on the microcomputer side, a periodic signal is input from an external periodic signal generation circuit to a signal route that allows confirmation of normal / abnormal computer operation, and the presence / absence of a periodic signal output after passing the signal route is checked by a watch dock. A failure such as a microcomputer runaway is detected by monitoring with a timer, and the solenoid drive circuit side is provided with a fail detection circuit for monitoring the drive current applied to the solenoid with a comparison circuit or the like.

However, in this case, since it is necessary to provide the fail monitoring means in each of the microcomputer and the solenoid drive circuit, the configuration becomes complicated and the cost becomes disadvantageous.

Further, the applicant of the present application has previously disclosed in Japanese Patent Application No. 62-220459 a periodic signal generating circuit provided between a microcomputer and a solenoid driving circuit as shown in FIG. We proposed a device that detects the failure of the load drive control system by monitoring the presence or absence of current dither.

However, in this prior art, the fail detection of the microcomputer itself cannot be performed because the fail detection is performed in the latter stage of the signal output from the microcomputer, and the watch dock timer and the like as described above are not provided. Fail monitoring means is required.

The present invention has been made by paying attention to the above-mentioned problems, and in a fail detection device of a load drive control system having a microcomputer and a load drive control circuit as an electronic control system, it is structurally simple and cost-effective. An object of the present invention is to simultaneously monitor the fail of both the microcomputer and the load drive control circuit by one fail detecting means.

(Means for Solving the Problem) In the load drive control system fail detecting device of the present invention for solving the above problem, the microcomputer is provided with a dither current signal setting function and is output from the load drive control circuit. A means for detecting a failure was made by monitoring the presence or absence of dither in the drive current with dither.

That is, as shown in the claim correspondence diagram of FIG. 1, it is set in accordance with a drive current signal setting unit a for setting a drive current signal based on a command signal obtained according to the control content, and an operation signal of the microcomputer. Dither current signal setting part b
A microcomputer d having a signal adding section c for superimposing a dither current signal on the drive current signal to generate a dither drive current signal; and a dither drive current applied to a load e based on the dither drive current signal. And a load drive control system failure detection means g for detecting a failure of at least one of the microcomputer d and the load drive control circuit f by monitoring the presence or absence of dither in the drive current with dither.
And are provided.

(Operation) At the time of fail detection of the load drive control system, the load drive control system fail detection means g inputs the drive current with dither applied from the load drive control circuit f to the load e and detects the failure by monitoring the presence or absence of dither. To be done.

When the failure is detected and the microcomputer d is not operating normally, the dither current signal setting section b, which performs the setting operation according to the normal operation of the microcomputer d, does not set the dither current signal. , Normality / abnormality of the microcomputer d is detected by dither monitoring, and
When the load drive control circuit f fails, the dither disappears from the dithered drive current, so that normality / abnormality of the load drive control circuit f is detected by dither monitoring.

Therefore, it is possible to monitor the failure of at least one of the microcomputer d and the load drive control circuit f by the single load drive control system failure detecting means g which is structurally simple and advantageous in terms of cost.

(Example) Hereinafter, the Example of this invention is described in detail based on drawing.

FIG. 2 is a diagram showing an overall configuration of a four-wheel steering vehicle equipped with a rear wheel steering control system to which the load drive control system fail detection device of the embodiment is applied.

First, the configuration will be described.

In Fig. 2, 1L and 1R are left and right front wheels, 2L and 2R are left and right rear wheels, 3
Is a handle. The front wheels 1L, 1R can be steered via the steering gear 4 by the steering wheel 3, respectively, and the rear wheels 2L, 2R
Can be steered by the rear wheel steering actuators 5, respectively.

The rear wheel steering actuator 5 is a spring center type hydraulic actuator, and when supplying hydraulic pressure to the chamber 5R, the rear wheels 2L and 2R are steered to the right by steering angles proportional to the pressure, respectively.
When supplying hydraulic pressure to L, the rear wheel 2L,
Each of the 2Rs shall be steered to the left.

An electromagnetic proportional rear wheel steering control valve 6 for controlling the hydraulic pressure to the actuator chambers 5L, 5R is provided, and this valve 6 has a structure in which variable throttles 6a, 6b, 6c, 6d are connected in a bridge, and a pump 7 is connected to this bridge circuit. , Reservoir 8 and actuator chamber 5
Connect oil passages 9 and 10 from L and 5R respectively.

The control valve 6 is further provided with solenoids 6L and 6R, and when the solenoids 6L and 6R are OFF, the variable throttles 6a and 6R are respectively provided.
b and 6c, 6d are fully opened so that both actuator chambers 5L, 5R are pressureless, and the solenoid 6L or 6R drive current with dither
When turned on by I _L ^* or I _R ^* , the variable throttles 6c, 6d or 6a, 6b are throttled to an opening according to the current value, and the dithered drive current I _L ^* or I _R ^* is supplied to the actuator chamber 5L or 5R. A hydraulic pressure corresponding to the value shall be supplied. As described above, this hydraulic pressure steers the rear wheels 2L, 2R in the corresponding direction by an angle corresponding to the value.

Oil passages 9 and 10 between the electromagnetic proportional type rear wheel steering control valve 6 and the rear wheel steering actuator 5 (the oil passages before and after the cut valve 20 are 9-1, 9-2 and 10-1, 10-, respectively). A cut valve 20 having a solenoid opening / closing valve structure is inserted in the middle of (2).

This cut valve 20 is normally closed and the ignition is OFF.
When the solenoid drive current I _F is not supplied to the solenoid 20a at the time of failure or at the time of failure, between the oil passages 9-1, 9-2 and 10-1,
10-2 while blocked is when being conducted rear wheel steering control properly, when the solenoid drive current I _F is supplied, between the oil passage 9-1, 9-2 and 10-1 Connect between 10-2.

When the cut valve 20 closes and fails,
Microcomputer runaway, sensor abnormality, control valve 6 solenoid
When 6L and 6R are broken or short-circuited and fail, the cut lamp 20 is closed and the alarm lamp 21 is turned on.

Drive current I with dither on the control valve solenoids 6L and 6R
_L ^* or I _R ^* or applied to, or by applying a solenoid driving current I _F to the cut valve solenoid 20a, ON the alarm lamp 21
・ Rear wheel steering control unit 30 that applies an OFF signal
The steering wheel steering angle sensor 40 for detecting the steering direction and steering angle of the steering wheel by the steering angle signal θ, and the neutral position signal θ _c for the neutral position of the steering wheel within a predetermined steering angle range. The steering wheel neutral position sensor 41 for detecting the vehicle speed, the vehicle speed sensor 42 for detecting the vehicle speed by the vehicle speed signal V, the ignition switch 43 and the like are connected.

As shown in the block diagram of FIG. 3, the rear wheel steering control unit 30 has an A / D converter 30a, a digital microcomputer 31, a D / A converter 30b, a solenoid drive circuit 30c, and a solenoid drive. Circuit 30d, display drive circuit 30e, differentiation circuit 30f, watch dock timer 30g
Is equipped with.

The digital microcomputer 31 includes, as internal circuits, a front wheel steering angle calculation circuit 31a and a rear wheel steering angle calculation circuit 3
1b, θ _R -I conversion circuit 31c, dither current signal setting circuit 31
d, a signal addition circuit 31e, a load model 31f, a comparison circuit 31g, and a fail safe circuit 31h.

Next, the operation will be described.

(A) Fail detection operation FIG. 4 is a flowchart showing the flow of the fail detection operation of the solenoid drive control system for the control valve solenoids 6L and 6R which is started after the ignition switch 43 is turned on.

* Fail detection stop processing Steps 50 to 52 are fail detection stop processing steps.

In step 50, the control valve solenoid 6
In the load model 31f that simulates the same response as L and 6R,
The drive current signals I _L and I _R are input.

In step 51, load model by digital filter
At 31f, the input signals I _L and I _R are converted into output signals I _L ′ and I _R ′ by the filtering process.

In step 52, the load circuit 31f
It is determined whether the input / output signal difference ΔI is less than or equal to the threshold value K, and when it is determined that ΔI> K and the input is in a transition state where the input changes rapidly, the process jumps to step 56, and step 53
The subsequent file detection process is stopped, and when it is determined that ΔI ≦ K and the input change is small, the process proceeds to step 53 and subsequent file detection processes.

That is, the control valve solenoids 6L and 6R are inductance loads, and the solenoid drive circuit 30c of the control valve solenoids 6L and 6R is a constant current circuit that uses a fixed power supply voltage E. For such an input, the current is regulated by the transient response of the inductance, the constant current circuit is saturated, and the power supply voltage E is output.

As a result, when the input to the solenoid drive circuit 30c is in transition, the drive current in which the dither has disappeared is output from the solenoid drive circuit 30c, and the pulse signal disappears during input transition, resulting in erroneous fail detection.

Therefore, at the time of such an input transient to the solenoid drive circuit 30c, at the previous stage of the solenoid drive circuit 30c by using the load model 31f that simulates the same response as the control valve solenoids 6L and 6R, whether it is the input transient or not. Predictive detection is performed, and fail detection is stopped when input transient is predictively detected.Therefore, it is possible to prevent erroneous fail detection by dither presence monitoring during input transient to the solenoid drive circuit 30c. Fail detection is ensured.

* Fail detection processing Steps 53 to 57 are fail detection processing steps.

In step 53, the drive current I _L ^* , I with dither applied to the control valve solenoids 6L, 6R in the differentiating circuit 30f is used.
_R ^* , solenoid drive circuit 30c and control valve solenoid 6
A pulse signal corresponding to dither is obtained by branching from a harness that connects L and 6R and inputting it.

In step 54, the watch dock timer 30g counts the number of constant time pulses based on the dither-corresponding pulse signal input from the differentiating circuit 30f.

In step 55, in the fail-safe circuit 31h, it is determined whether or not the pulse count number from the watch dock timer 30g is a normal pulse count number according to the dither frequency. A normal command for maintaining the rear wheel steering control is output to 56, and when the count number is zero, a fail command for starting a fail operation described later is output to step 57.

That is, the solenoid drive circuit 30c and the control valve solenoid 6
When the harness connecting L and 6R is broken, the drive current does not flow through the harness, and when the harness is short-circuited, a linear constant current corresponding to the fixed power supply voltage E flows. In other words, since dither will be lost in any of the fail modes, the dither-equipped drive currents I _L ^* and I _R ^* are input from the harness connected to the control valve solenoids 6L and 6R to monitor the presence or absence of dither. By performing the above, it is possible to detect the disconnection of the harness or the failure of the short circuit.

Then, dither with the drive current I _L ^* used in this fail detection, I _R ^*, regardless of the current value of the drive current, because a current obtained by superposing the dither current, the drive with the dither current I _L Even if the current value of ^* , I _R ^* is zero, the differential signal of the drive current I _L ^* , I _R ^* becomes a pulse signal, so that fail detection can be performed, and fail detection is performed by comparing the conventional linear drive current. As in the case, if the harness is broken when the drive current is zero or if the harness is short-circuited while the drive current is flowing, the fail detection will not become undetectable and will not be limited by the timing of detection. It becomes possible to detect.

Therefore, although it is more cost-effective than the case of using a large number of comparison circuits, it is possible to always detect the failure of the harness disconnection or short circuit with high detection accuracy regardless of whether the drive current is applied or not applied. .

Further, a digital microcomputer 31 having a dither current signal setting circuit 31d in its internal circuit, and a dither-equipped drive current signal (I
_L ^*), (I _R ^* control valve solenoids 6L based on), the driving current with the dither applied to 6R I _L ^*, a solenoid driving circuit 30c to produce the I _R ^*, with the dither from the solenoid drive circuit 30c Since the fail is detected by the presence / absence of dithering of the drive currents I _L ^* and I _R ^* , the digital microcomputer 31 and the solenoid are driven by a single dither monitoring circuit such as the differentiating circuit 30f or the watch dock timer 30g. Both failures of circuit 30c can be detected.

That is, when the digital microcomputer 31 is not operating normally, the dither current signal setting circuit 31 that performs the setting operation according to the normal operation of the microcomputer 31.
Since the dither current signal _ID is not set by d, normality / abnormality of the digital microcomputer 31 is detected by dither monitoring.

When the solenoid drive circuit 30c fails, the dithered drive currents I _L ^* , I _R ^* or the dither disappears,
Normality / abnormality of the solenoid drive circuit 30c is detected by dither monitoring.

As described above, in the fail detecting device according to the embodiment, the digital microcomputer 31 and the solenoid drive circuit 30 are not limited to the fail detection of the wire breakage and the short circuit of the harness.
Fail detection of the solenoid drive control system including c can be detected by a single dither monitoring means.

(B) Rear Wheel Steering Control and Fail-Safe Operation FIG. 5 is a flowchart showing the flow of the rear wheel steering control operation and the fail-safe operation performed by the control cycle of 5 msec.

In step 60, it is judged whether or not the control is started for the first time.

In step 61, the dither flag D is set to D = 0 and the timer values T _P and T _M are set to T _P and T _M = 0.
Necessary initialization processing is performed.

In step 62, it is determined whether or not the fail command is being output.If the fail command is not output, the rear wheel steering control operation after step 63 is performed, and if the fail command is output, the step after 82 is performed. Fail-safe operation is performed.

* Rear wheel steering control operation In step 63, the steering angle signal θ, the neutral steering angle signal θ _c, and the vehicle speed signal V are read.

In step 64, the neutral steering angle estimated value θ _CM obtained based on the steering angle signal θ and the neutral steering angle signal θ _c and the steering angle signal θ
And the front wheel steering angle signal θ _F is calculated by the following equation.

θ _F = | θ−θ _CM | In step 65, the target rear wheel turning angle signal θ _R is calculated based on the vehicle speed signal V and the front wheel steering angle signal θ _F.

In step 66, the target rear wheel turning angle signal θ _R is given in advance by the drive current signal I _L or I according to the θ _R -I characteristic table.
Converted to _R.

In step 67, the dither flag D is either D = 1 or D = 0 is determined, when D = 0, the process proceeds to step 68 to step 73 of applying a dither current signal -I _D per 50 msec,
Further, when D = 1, the process proceeds to steps 74 to 79 in which a + _ID dither current signal is applied every 50 msec.

In step 68, in the dither current signal setting circuit 31d, the drive current signal I _L input from the θ _R -I conversion circuit 31c
Or a dither current signal I _D corresponding to the drive current signal I _L or I _R based on I _R and the dither current signal characteristic shown in FIG. 6 (for example, a signal corresponding to a dither current 50 mA)
Is set.

In step 69, the timer value T _M is set to 1 every time the control is started.
Is added one by one.

In step 70, it is determined whether or not the timer value T _M is 11 or more. If T _M <11, the process proceeds to step 73, and in the signal addition circuit 31e, the drive current signal with dither (I _L ^* ) is calculated by the following equation. , (I _R ^* ) is calculated, and when T _M = 11, step 7
At 1 it is rewritten to D = 0 and at step 72 it is rewritten to T _P = 0.

(I _L ^* ) = I _L −I _D (I _R ^* ) = I _R −I _{D In} step 74, as in step 68, the dither current signal setting circuit 31d inputs from the θ _R −I conversion circuit 31c. Based on the driving current signal I _L or I _R and the dither current signal characteristic shown in FIG. 6, the dither current signal I _D corresponding to the driving current signal I _L or I _R is set.

In step 75, the timer value T _P is set to 1 every time the control is started.
Is added one by one.

In step 76, it is determined whether the timer value T _P is 11 or more. If T _P <11, the process proceeds to step 79, and in the signal addition circuit 31e, the drive current signal with dither (I _L ^* ) is calculated by the following formula. , (I _R ^* ) is calculated, and when T _P = 11, step 7
At 7 it is rewritten to D = 0 and at step 78 it is rewritten to T _M = 0.

(I _L ^* ) = I _L + I _D (I _R ^* ) = I _R + I _{D In} step 80, the dither current is added to the drive current in the solenoid drive circuit 30c based on the signal obtained in step 73 or step 79. The combined dithered drive current I _L ^* or I _R ^* is output to the control valve solenoid 6L or 6R.

That is, when the microcomputer 3 is operating normally, step 71 and step 77 are always executed.
A dither signal with a constant frequency that changes every msec is output.

In step 81, the solenoid driving current I _F according to ON signal to the valve solenoid 20a opens the cut valve 20 is output.

Therefore, in the rear wheel steering control operation, for example, as shown in FIG. 7, the rear wheels are momentarily controlled to be in a reverse phase with respect to the front wheel steering angle θ _F , and thereafter, the rear wheels are controlled to be in the same phase. When the phase reversal control is performed, the rise of the yaw rate is improved by positively adding the generation of cornering force in the yaw generation direction, and after the sufficient yawing is obtained, the rear wheels are switched to the in-phase side. By steering to suppress the increase in yaw rate, the side slip angle of the vehicle body is suppressed, steering stability is increased, and high steering response is obtained.

The phase inversion control of the first-order advance is particularly effective in the low and medium speed regions because the phase inversion timing becomes faster as the vehicle speed becomes higher and becomes similar to the in-phase control at high speed.

Also, when setting the dither, it is set to a constant frequency that changes every 50 msec, but the dither amplitude determined by the magnitude of the dither current is the current of the drive current signal I _L or I _R as shown in FIG. When the level is below I ₀ and small, the dither effect is strong and the amplitude is set to a large value.
When the current level of I _L or I _R exceeds I ₀ , the amplitude is gradually reduced to diminish the effect of dither, which improves the hydraulic response when the drive current is small, and It is possible to achieve both reduction of vibration and generation of abnormal noise when the current is large.

That is, when looking at the control hydraulic pressure-driving current characteristic, there is a hysteresis in the driving current when the hydraulic pressure is increasing and when the hydraulic pressure is decreasing, and this hysteresis deteriorates the hydraulic response. Therefore, it is necessary to increase the dither effect by a method such as increasing the dither amplitude.However, if the dither effect is increased over the entire drive current range, the hydraulic response is improved,
The dither current, which has a strong effect in the large current range, makes the hydraulic pressure fluctuate significantly, causing vibration and abnormal noise.

The dither current is used for the purpose of detecting the above-mentioned failure, the purpose of achieving both the improvement of the hydraulic response and the reduction of vibration and abnormal noise, and the purpose of constantly giving a subtle vibration to the spool of the control valve 6 to suppress stick-slip. , Etc., but the dither current of amplitude and frequency set in the embodiment (amplitude ± 0.1A or less, frequency
100 Hz) satisfies all of these purposes and does not affect the original rear wheel steering control by the control valve 6.

* Fail-safe operation In step 82, the solenoid drive current _IF is output to the valve solenoid 20a by an OFF signal that closes the cut valve 20.

In step 83, a lighting signal (ON) is output to the alarm lamp 21.

At step 84, the elapsed time Δ from the failsafe command
It is checked whether T has reached a predetermined time ΔT ₀ (for example, 150 msec), and when ΔT ≧ ΔT ₀ , in step 86, the drive current I _L with the dither 6L or 6R of the control valve 6 is attached.
A command to turn off ^* or I _R ^* is output.

Therefore, in fail-safe operation, the oil pressure is cut by the cut valve 20, and then the oil leak from the cut valve 20 is used to gradually return the rear wheels to the neutral position. The sudden change in vehicle behavior is prevented.

Although the embodiment has been described above with reference to the drawings, the specific configuration and control contents are not limited to this embodiment.

For example, although the example of the rear wheel steering control system is shown as the load drive control system fail detection device in the embodiment, an auxiliary steering control system and an active suspension control system that steer the front wheels and the rear wheels by steering when steering the front wheels. Of course, a torque split control system, an anti-lock brake control system, or the like can be applied as long as it is a control system that drives and controls a predetermined inductance load by a drive current.

Further, in the embodiment, the example in which the solenoid valve that creates the control hydraulic pressure for the hydraulic actuator is used as the load has been described.
It can also be applied to various control systems with loads such as solenoid actuators and motor actuators.

(Effect of the Invention) As described above, in the load drive control system fail detection device of the present invention, the dither current signal setting function is provided inside the microcomputer, and the dither output from the load drive control circuit is provided. Since it is a means for detecting a failure by monitoring the presence or absence of a dither in the attached drive current, a failure detection device of a load drive control system having a microcomputer and a load drive control circuit as an electronic control system is structurally simple and advantageous in terms of cost. With such a single fail detecting means, it is possible to simultaneously monitor the fail of both the microcomputer and the load drive control circuit.

[Brief description of drawings]

FIG. 1 is a diagram corresponding to claims of a load drive control system failure detection device of the present invention, and FIG. 2 is an entire four-wheel steering vehicle equipped with a rear wheel steering control system to which the load drive control system failure detection device of the embodiment is applied. FIG. 3 is a block diagram of a rear wheel steering control unit of a rear wheel steering control system, FIG. 4 is a flow chart showing a flow of a fail detection processing operation in an embodying device, and FIG. 5 is a rear wheel steering. FIG. 6 is a flowchart showing the flow of control operation and fail-safe operation, FIG. 6 is a dither current signal characteristic diagram with respect to the drive current signal, FIG. 7 is a time chart showing an example of rear wheel steering control, and FIG. 8 is conventional load drive control. FIG. 9 is a block diagram showing an example of a system failure detection device, and FIG. 9 is a block diagram showing an example of a preceding load drive control system failure detection device. a: Drive current signal setting section b: Dither current signal setting section c: Signal addition section d: Microcomputer e: Load f: Load drive control circuit g: Load drive control system failure detection means

Claims (1)

[Claims] 1. A drive current signal setting section for setting a drive current signal based on a command signal obtained according to control contents, a dither current signal setting section set according to an operation signal of a microcomputer, and the drive current. A microcomputer having a signal adder that superimposes a dither current signal on a signal to produce a dithered drive current signal; and a load drive control circuit that produces a dithered drive current applied to a load based on the dithered drive current signal, A load drive control system failure detecting means for detecting a failure of at least one of the microcomputer and the load drive control circuit by monitoring the presence or absence of dither of the drive current with dither, and a load drive control system failure. Detection device.