JPH0534003Y2 - - Google Patents

Description

[Detailed description of the invention] Purpose of the invention Industrial field of application The invention is a potentiometer that is composed of multiple control devices mainly including microcomputers and is used for vehicle engine control, driving control, etc. The present invention relates to a control system equipped with a control system.

BACKGROUND OF THE INVENTION Engine control and driving control of automobiles are performed using processors mainly based on microcomputers.

In such a control system, a functionally distributed multi-processor system configuration may be adopted in which a plurality of processors with different control targets are installed. In such a control system, a plurality of processors read the value of a potentiometer that converts a state value of a controlled object, such as the opening degree of a throttle valve, into a voltage value.

That is, as illustrated in FIG. 2, one processor 10 includes a microcomputer 11, an A/D converter 12, a regulator 13, and an output circuit 14;
D converter 22, regulator 23, output circuit 24
A power supply line 42 is connected from the battery 41 to the other processor 20 equipped with the
A power supply voltage is supplied through the ground line 43 and the ground line 43 . The low voltage side terminal 31 of the potentiometer 30 is connected to the ground wire 4
Connected to 4. An applied voltage is supplied from the applied voltage generator 25 in the processor 20 to the high voltage side terminal 33 of the potentiometer 30, and the high voltage side of the potentiometer 30 is supplied by the A/D converters 12 and 22 of both processors. The voltage applied to the terminal 33 and the voltage divided by the slider at the terminal 32 are read.

Problems to be Solved by the Invention In the conventional control system illustrated in FIG. 2, the low voltage side terminal 31 of the potentiometer is connected to a grounding wire 44. Each time an actuator is driven by circuit 14 or 24, a significant amount of current flows.
For this reason, the A/D converter 12 in each processor,
ground potential at 22 and potentiometer 30
A potential difference corresponding to the magnitude of the voltage drop that occurs on the ground line 44 is created between the ground potential and the ground potential, which causes an error in the potentiometer reading by that amount. This reading error becomes a problem when attempting to perform highly accurate control.

Means for Solving the Constituent Problems of the Invention A control system equipped with a potentiometer according to the present invention which solves the problems of the prior art described above is characterized in that at least one processor connects the low voltage side terminal of the potentiometer via a resistor. an operational amplifier having one input terminal connected to the potentiometer, and selectively transmits the applied voltage value applied to the potentiometer and its divided voltage value to the other input terminal of the operational amplifier via a voltage divider. is configured to prevent reading errors associated with voltage drops on the ground wire in conventional systems by reading the voltage value of the potentiometer by coupling the output voltages of the operational amplifier to There is.

Hereinafter, the operation of the present invention will be explained in detail together with examples.

Embodiment FIG. 1 is a block diagram showing the configuration of a control system equipped with a potentiometer according to an embodiment of the present invention.

In FIG. 1, components labeled with the same reference numerals as in the conventional system shown in FIG. 2 are the same as the components already described with respect to FIG. Therefore, redundant explanation of these components will be omitted.

In the system of this embodiment, an operational amplifier 15 is installed before the A/D converter 12 in the processor 10. The low voltage side terminal 31 of the potentiometer 30 is connected to the inverting input terminal of the operational amplifier 15 via the resistor R ₁ , and the high voltage side terminal 33 and voltage dividing terminal 32 are selectively opened and closed based on commands from the microcomputer 11. Switches 16 and 17
and a non-inverting input terminal of the operational amplifier 15 via a voltage divider 18 composed of resistors R ₃ and R ₄ .

The relationship between the resistors R ₁ to R ₃ and the resistance value of the feedback resistor R ₄ of the operational amplifier 15 is set as follows.

R ₁ = R ₃ , R ₂ = R ₄ ...(1) At any given time, the potential of the low voltage side terminal 31 of the potentiometer 30 is V ₁ , and the voltage dividing terminal 3
2 is _V2 , and the potential of the high voltage side terminal 32 is _V3 . When reading the voltage value of the potentiometer 30, the microcomputer 12 in the processor 10 first opens the switch 17 and closes the switch 16 to start reading the voltage value applied to the high voltage side terminal 33. If the output voltage of the operational amplifier 15 in this state is V ₀₁ , the following equation holds true due to the inherent property of operational amplifiers that the voltages at both input terminals are equal.

(V ₀₁ −V ₁ ) × R ₁ / (R ₁ + R ₂ ) + V ₁ = V ₃ × R ₄ /
(R ₃ +R ₄ )...(2) Here, if we use the relationship in equation (1), equation (2) becomes as follows.

V ₀₁ = (R ₂ /R ₁ ) (V ₃ -V ₁ )...(3) The microcomputer 12 is the D/A converter 1
When the storage of the read data V ₀₁ converted into a digital value by step 2 is completed, the switch 16 is opened and the switch 17 is closed to start reading the partial voltage value of the voltage dividing terminal 32. In this state,
If the output voltage of the operational amplifier 15 is V ₀₂ , the following equation holds true due to the property of the operational amplifier that the voltages at both input terminals are equal.

(V ₀₂ −V ₁ ) × R ₁ / (R ₁ + R ₂ ) + V ₁ = V ₂ × V ₄ /
(R ₃ + R ₄ ) ...(4) Using the relationship in equation (1) again, equation (4) becomes as follows.

V ₀₂ = (R ₂ /R ₁ ) (V ₂ -V ₁ )...(5) The microcomputer 12 is the D/A converter 1
When reading of the read data V ₀₂ converted into a digital value by step 2 is completed, this read data is divided by the immediately previous read data V ₀₁ . That is, from equations (3) and (5), the following equation can be obtained.

V ₀₂ /V ₀₁ =(V ₂ −V ₁ )/(V ₃ −V ₁ ) (6) This division result matches the correct voltage value of the potentiometer 30 as the target.

The microcomputer 21 of the other processor 20, like the conventional system, reads the voltage value of the potentiometer 30 directly through the A/D converter 22. Since the operational amplifier 15 with high input impedance is connected to the ground line 45 to which the low voltage side terminal 31 of the potentiometer 30 is connected, no current flows between the processors via this ground line 45, and no error problem due to the voltage drop occurs.

As described above, the voltage generator 25 applied to the processor 10 side
Although the configuration in which the processor is installed is illustrated, it may be installed on the processor 10 side.

Furthermore, although a control system configured with two processors has been illustrated, it is clear that the present invention can also be applied to a control system configured with an appropriate number of processors, such as three or more. In this case, the 3rd, 4th
All of the second processors may have the same configuration as the processor 10, or some of the processors that do not require such high precision may have the same configuration as the processor 20.

Effects of the Invention As explained in detail above, in the control system of the present invention, at least one processor selectively controls each of the applied voltage value applied to the potentiometer and its partial voltage value via an operational amplifier. Since the voltage value of the potentiometer is read by calculating the ratio between the two values, it is possible to effectively prevent reading errors due to voltage drops occurring in the ground line.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a control system equipped with a potentiometer according to an embodiment of the present invention, and FIG. 2 is a block diagram showing the configuration of a conventional control system. 10, 20... Processor, 15... Operational amplifier, 16, 17... Switch selectively opened and closed by the microcomputer 11 in the processor 10, 18... Voltage divider, 25... Applied voltage generator, 30... Potentiometer, 31... Low voltage side terminal, 32... Voltage dividing terminal, 33... High voltage side terminal,
43, 45...Grounding wire.

Claims (1)

[Claims for Utility Model Registration] In a control system equipped with a plurality of processors and a common potentiometer whose voltage value is read by the plurality of processors, at least one processor has a low voltage side input terminal. is connected to the low voltage side terminal of the potentiometer and has a high voltage side input terminal connected to a reference power supply, and another processor is connected to the low voltage side terminal of the potentiometer via a resistor. an operational amplifier having one input terminal connected to the potentiometer, and selectively transmitting each of the applied voltage value applied to the potentiometer and its divided voltage value to the other input terminal of the operational amplifier via a voltage divider; , and the voltage value of the potentiometer is read by calculating the ratio of the output voltage obtained by amplifying the difference between the voltages supplied to each input terminal of the operational amplifier. Control system with meter.