JPH03216701A - Safe circuit for travel controller for vehicle - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention provides an anti-skid system for vehicles. Traction control. This invention relates to a safety circuit for a vehicle travel control device that accurately detects abnormalities or failures in a microcomputer used to control a constant speed travel device, etc., and can reliably stop actuator drive.

[Conventional technology]

FIG. 3 shows a conventional so-called watchdog circuit shown in, for example, Japanese Patent Laid-Open No. 60-250445. In FIG. 3, the period detection means 2a of the watchdog circuit 2 detects the presence or absence of a pulse signal of a constant period outputted from the microcomputer 1, and the period detection means 2a detects that the pulse signal is no longer generated. When detected, the cycle detection means 2a outputs a signal to the reset generation stage 2b, and the reset generation means 2b sends a reset signal to the microcomputer 1, thereby resetting the microcomputer l. As a result, there is no output from the microcomputer 1 to the driving means 3, and the operation of the actuator 4 is stopped to protect the actuator 4. Further, FIG. 4 is a block diagram showing a schematic configuration of an anti-skid control interrupting device for explaining a conventional anti-skid control interrupting method disclosed in, for example, Japanese Unexamined Patent Publication No. 185663/1983. In the case of this figure 4,
The system abnormality detection circuit 12 detects the presence or absence of an abnormality in the output signal output from the control circuit l1, and when the system abnormality detection circuit 12 does not detect an abnormality, it is not output.
The output of T circuit l3 is output to AND circuit l4. AN
The D circuit 14 is an AND of the drive signal for the actuator 15 output from the control circuit 1l and the output of the NOT circuit 13.
When the system abnormality detection circuit l2 does not detect an abnormality in the control circuit l1, this drive signal is output to the AND circuit 14.
The signal is input to the drive circuit 16 through. As a result, the drive circuit l6 drives the actuator 15. On the other hand, if there is an abnormality in the output signal from the control circuit 1l, the system abnormality detection circuit 12 detects the system abnormality, and the output is N
It is inverted by OT circuit l3. Therefore, the control circuit 1l
Even if the drive signal is output from the actuator l4, the AND condition in the AND circuit l4 is not satisfied and the drive signal is not input from the AND circuit l4 to the drive means l6.
5 is inactive. Note that 17 is an input signal circuit that sends various input signals to the microcomputer l1. [Problems to be Solved by the Invention] In the conventional example shown in FIG. Situations may occur where it is impossible to deactivate. Furthermore, in the case of the conventional example shown in FIG. 4, when a failure occurs in the AND circuit l4 or the drive means 16, the actuator l
There was a problem that the drive of 5 could not be stopped. This invention was made to solve the above-mentioned problems, and provides a vehicle travel control device that can accurately detect abnormalities in a microcomputer and reliably stop actuator drive when an abnormality occurs. The purpose is to obtain a safety circuit. [Means for Solving the Problems] The safety circuit of the vehicle travel control device according to the present invention includes a watchdog that outputs a reset signal to the microcomputer when the cycle of the first output pulse output from the microcomputer is abnormal. means detecting the deity of the second output pulse output from the microcomputer;
The actuator is equipped with a duty detection means that generates an output signal when the duty is outside a predetermined duty range, and a power cutoff means that cuts off the power to the actuator in response to a reset signal or an output signal from the duty detection means. [Function] When the cycle of the first output pulse output from the microcomputer in the second invention is abnormal with respect to a predetermined cycle, the watchdog detection means outputs a reset signal to reset at least the microcomputer. At the same time, when the duty detection means detects the duty of the second output pulse and detects that the duty is outside the predetermined duty range, the power supply cutoff means cuts off the power and puts the actuator in a non-operating state. [Example] Hereinafter, an example of the safety circuit of the vehicle running control device of the present invention will be described based on the drawings. Figure 1 is a block diagram showing the configuration of one embodiment. In this FIG. 1, 2l is an actuator that drives the controlled object,
22 is a signal input means for sending various input signals to the microcomputer 23. The microcomputer 23 is configured to output a signal for driving the actuator 21 to the driving means 24 in accordance with the results of calculations and judgments made from the input signal information from the signal input means 22. The driving means 24 is configured to drive the actuator 21 based on the signal output from the microcomputer 23.

On the other hand, 25 detects this dark period by receiving the first pulse signal periodically output from the microcomputer 23,
This is a watchdog means that outputs a first abnormal signal to the microcomputer 23 when the cycle is longer than a predetermined cycle.

The first abnormal signal outputted from the watchdog means 25 is outputted not only to the microcomputer 23 but also to a power cutoff means 27, which will be described later.

Further, the duty detection means 26 inputs the second output pulse outputted from the microcomputer 23, detects the duty of this second output pulse, and when detecting a duty outside a predetermined duty range, generates a second abnormal signal. is output to the power cutoff means 27.

This'r! The lfl cutoff means 27 is configured to cut off the power to the actuator 2l when the first abnormal signal output from the 1,000-stage wait dong 25 or the second abnormal signal output from the 1,000-stage duty detection stage 26 occurs. It has become. Next, a specific embodiment of the present invention will be described with reference to FIG. 2, in which the invention is applied to an anti-skid device.

The anti-skid device includes a solenoid valve 21a inside an actuator 21 that increases and decreases brake pressure. 2lb, and transistors 24a. 24b is provided. Transistors 24a and 24b of this drive stage 24 are turned on by a signal from the microcomputer 23 to drive the solenoid valves 21a and 2lb. Further, as the signal input means 22, wheel speed signals 22a and 22b output from the wheel speed sensors are input to the amplifier 2, respectively.
The signal is input to the microcomputer 23 via 2c and 22d.

The first output pulse 29 periodically outputted from this microcomputer 23 is connected to the capacitor C + + and the resistor Rl.
+ and the differentiating circuit is passed through the diode DI1 to operate the frimb flop circuit 30, and with this period,
Transistor Q1 is turned on.

The emitter of the transistor Q is grounded, and the collector is connected to the connection point P1 between the resistor R1 and the capacitor CI through the resistor R2. This resistor R and capacitor C1 are connected in series between is and ground.

A connection point P1 between the resistor R and the capacitor C1 is connected to the (g) input terminal of the converter 10b.

(E) Input terminal of comparator 10b and comparator 10
The day input terminal of a is common.

Also, there is a resistor Rl! between the power supply and ground! ~RI4 series circuits are connected. The comparison voltage (1) at the connection point between the resistors Rl2 and Rl3 is applied to the (c) input terminal of the converter 10b.

Similarly, the comparison voltage (2) at the connection point between the resistors R13 and RI4 is connected to the (G) input terminal of the converter 10a. The outputs of the converters 10a and 10b are connected to the input terminal of a flip-flop circuit 31. The output of flip-flop circuits 30 and 31 is OR gate 3
2 is supplied to the pace of the transistor Q1. Thus, capacitors C, , C++, resistors R. R!
R1+~RI4, flip-flop circuit 30.3
1. OR circuit 32, diode D, transistor Q+
．． Q- constitutes a watchdog means 25. Note that the output of the flip-flop circuit 31 is input to the base of the transistor Q2, the emitter of this transistor Q2 is grounded, and the reset signal of the microcomputer 23 is output from the collector. It has become.

On the other hand, the second output pulse 33 output from the microcomputer 23 is inputted to the H input terminal of the comparator 34a and the (G) input terminal of the converter 34b via an integrating circuit including a resistor R and a capacitor C. It has become. Furthermore, the resistor R+s#R I7 is connected in series between the power supply and the ground, and the voltage 3 at the connection point between the resistors RIB and Rl& is applied to the (e) input terminal of the converter 34a. There is. Similarly, resistor Rl& and resistor Rl? The voltage v4 at the connection point is applied to the H input terminal of the comparator 34b. Comparator 34a. The output of 34b is made common, and the abnormal duty detection output 35 is ANDed with the power cutoff means 27.
It is applied to the first human power end of the circuit 27a. In this way, comparators 34a. 34b, resistance R
+s-R+y+resistance R3+ A duty detection circuit 26 is configured by capacitor C. Further, the power supply cutoff means 27 includes an AND circuit 27a, a transistor Q3.
It is composed of a relay 27b, and the second
The human power end is connected to the reset terminal k of the microcomputer 23, and the transistor Qg of the watchdog means 25.
A reset signal is sent from the collector of the AND circuit 27a to the second
The reset signal is applied to the human power end, and the reset signal is also input to the reset terminal k of the micro combinator 23. A of the power cutoff means 27
The output of the ND circuit 27a is applied to the base of the transistor Q3, whose emitter is grounded and whose collector is connected to the power supply via the coil 27c of the relay 27b. A contact 27d of the relay 27b is connected to a power source and one end of the solenoid valve 218.2lb of the actuator 21.

Next, the operation of this invention will be explained according to FIG. The anti-skid device has an actuator 2l that increases and decreases brake pressure, and also has a signal input means 22.
A wheel speed signal is input to the microcomputer 23 as an input signal. The first signal periodically output from the microcomputer 23
Output pulse 29 is connected to capacitor CI1 and resistor R. The diode DI1 outputs only a positive differential pulse, and the next-stage flip-flop circuit 30 is activated at the rising edge of this first output pulse. Due to the period of this first output pulse 29, the output of the fritbfroon 1 circuit 30 is passed through the OR circuit 32 to the transistor Q. is added to the base of Q1, turning on transistor Q1. When the transistor Q1 is turned on, the charge that has been stored in the capacitor C through the resistor R1 is transferred to the resistor R!
is discharged from the collector of transistor Q1 through the emitter to ground. Transistor Q. When turned on momentarily at the rising edge of the first output pulse, it remains on until the rising edge of the next first output pulse, so this capacitor C1 is connected via the resistor R while the transistor Q1 is off. It will be charged. The voltage of the second capacitor C, is applied to the (c) input terminal of the comparator 10a and the (g) input terminal of the comparator 10b while the microcomputer 23 is outputting the first output pulse of the normal cycle. 7) Comparison voltage V
*, exists between Vt rD. Here, the first output pulse 2 of the microcomputer 23
9 does not occur at a predetermined period, that is, when the period of occurrence becomes longer, the off time of transistor Q+ becomes longer. As a result, the charging time of capacitor CI becomes longer and the charging voltage of capacitor CI increases. When the charging voltage of the capacitor C1 exceeds the comparison voltage V of the comparator 10b, an output is output from the comparator 10b, which activates the flip-flop circuit 31, and the output turns on the transistor Q8. Transistor Q. When turned on, a reset signal (low level) 28 is output from its collector and is input to the reset input terminal k of the microcomputer 23, as well as to the second human power terminal of the AND circuit 27a of the power cutoff means 27. It will be done.

In this way, the predetermined period of the first output pulse outputted from the microcomputer 23 is controlled by the watchdog means 2.
5, and when the q of the first output pulse exceeds a predetermined value or stops, a reset signal 2 is generated from the watchdog means 25.

This embodiment also has an automatic oscillation function that can periodically generate a reset signal if the microcomputer 23 does not output the first output pulse at a predetermined period. That is, when the first output pulse 29 is not generated periodically, as described above, the transistor Q is turned off, the charging voltage of the capacitor C increases, and the comparator 1
0a is compared with the comparison voltage ■2, and if this comparison voltage ■ is high, it is output from the comparator 10a, the flip-flop circuit 31 operates, and the output causes the transistor Q! is turned on, the reset signal 28 is output, and when the charging voltage of the capacitor C1 becomes equal to or higher than the comparison voltage V, the comparator 10a stops outputting. By repeating the above operations, the reset signal 28 can be generated periodically. Next, a second output pulse 33 is output from the microcomputer 23, and charges and discharges the capacitor C2 through the resistor R. It is assumed that this second output pulse 33 is outputted independently of the first output pulse 29 described above.

Furthermore, the rl{J level and “L” of the second output pulse 33
The level output width is set to 2:3, and the microcomputer 2
If the power supply voltage of capacitor C is 5V (not shown), the charging voltage of capacitor C will be around 2V. (c) Input terminal of comparator 34a and comparator 34
The charging voltage of the capacitor C, is applied to the (G) input terminal of the comparator 34a, and the comparison voltage ■, is applied to the (G) input terminal of the comparator 34a.
Comparison voltage ■4 is applied to the day input terminal of b. Now, these comparison voltages V3 and V4 are y and V4, respectively.
>2v, V. <2V, if a normal data pulse is output, the comparator 34a. 34b each outputs the rHJ level.

Furthermore, when the duty is disturbed, either of the comparison voltages 3 and 4 is applied to the comparator 34a. 34b becomes the "L" level, and the abnormal duty detection output 35 is output.

In this way, the duty of the second output pulse output from the microcomputer 23 can be detected by the duty detection circuit 26, and an abnormal duty detection output 35 is output.

This abnormal duty detection output 35 is transmitted to the actuator 27
is added to the first human power end of the AND circuit 27a, and this AN
The reset signal 28 is connected to the second manual terminal of the D circuit 27a.
is added. Either one of the AND circuits 27a is "L"
For example, when the abnormal duty detection output 35
When the signal becomes "L" level, the AND circuit 27a no longer outputs an output, and the transistor Q3 is turned off.

As a result, the coil 27c of the relay 27b driven by the transistor Q is deenergized, and its contact 27b is opened.

By opening this contact 27d, the current flow to the actuator 2l is cut off. Note that in the above embodiment, the abnormal duty detection signal 35 is input only to the power cutoff means 27, but
It is also possible to change the abnormal duty detection signal 35 so that the microcomputer 23 is reset.

〔Effect of the invention〕

As described above, according to the present invention, when an abnormality occurs in the period of the first output pulse output from the microcomputer, the microcomputer is reset by the reset signal output from the watchdog means, and
The abnormal duty of the second output pulse output from the microcomputer independently of the first output pulse is detected by the duty detection means, and the power cutoff means is caused to cut off the power to the actuator, or the microcomputer Since it is configured so that it can also reset the microcomputer, it is possible to cut off the power to the actuator in addition to resetting the microcomputer in the event of an abnormality in either the first or second output pulse. Therefore, the drive of the actuator can be stopped more reliably, and the safety of vehicle running can also be improved.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a safety circuit of a vehicle running control device according to an embodiment of the present invention, FIG. 2 is a circuit diagram showing a specific circuit configuration of the same embodiment, and FIG. 3 is a block diagram of a conventional watchdog timer. Block Diagram FIG. 4 is a block diagram of an anti-skid control device for explaining a conventional anti-skid control interruption method. 2l...Actuator, 22...Signal input means,
23...Microcombination unit, 24...Drive means, 25...Watchdog means, 26...Duty detection means, 27...Power cutoff means. In addition, the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] an actuator for driving a controlled object; a signal input means for sending various input signals to a microcomputer; a driving means for driving the actuator according to a result of processing and determining the input signal by the microcomputer;
The first signal periodically output from the microcomputer
watchdog means for detecting the period of the output pulse and outputting a reset signal to reset at least the microcomputer when the period of the first output pulse becomes abnormal; and the first output pulse output from the microcomputer. duty detecting means that detects the duty of the independent second output pulse and generates an abnormal duty detection output when an abnormal duty is detected; and a power source that turns off the power to the actuator in response to the reset signal or the abnormal duty detection output. A safety circuit for a vehicle running control device, which is equipped with a disconnection means.