JPS5973715A - Sensor processing system - Google Patents

Abstract

PURPOSE:To obtain the absolute value of the amount of displacement accurately, by the constitution wherein the structure of a position sensor is such that a limiting point detecting signal is generated at mechanical lower limit, and the contents of a memory circuit is updated by the present value when the absolute value at the time the limiting point detecting signal is generated sxceeds a preset reference value. CONSTITUTION:A switch 14 is normally switched to the side of a solid line, and two inputs to a difference detector 15 are both at a present value V. When a limiting point detecting signal LL (=0V) in the Figure is received, the switch 14 is turned to the side of broken line, and the two inputs to the difference detector 15 become the present value V and a lowest value Vmin. Then the difference detector 15 computes a differential output DIF=V-Vmin. Under the normal operation, the differential output DIF is small. When the lowest value Vmin in a memory circuit 10 is abnormally small, the differential output becomes large, the output of a comparator 16 becomes DIF>REF, and a switch 12 is turned ON. As a result, the present value V at the time when V>Vmin holds good is stored in the memory circuit 10 as the lowest value Vmin hereinafter.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sensor processing method for determining the absolute value of a displacement amount from the output of a mechanical position sensor.

The sensor processing method that calculates the absolute value of displacement by subtracting the minimum value from the current value of the sensor output that detects mechanical position (distance, angle, etc.) can be divided into the following two types depending on how the minimum value is handled. Separated. The first method is to detect the mechanical limit point (lower limit) of the sensor using limit-noto-isochi, etc., and set the sensor output at that time as the lowest value. In the second method, lower limit detection using a beam switch or the like is not performed, but the lowest value of the sensor output is updated and stored.

FIG. 2 shows a mechanical throttle opening sensor as a typical example of a position sensor used in an automobile. 1
2 is a voltage detection contact that slides into contact with the resistor according to the throttle opening, and 3 moves integrally with contact 2 to detect the sensor. This is a contact point for a limit switch that contacts terminal 4 at the mechanical lower limit. One end of the resistor 1 is connected to a power supply Vcc (for example, 5V), and the other end is connected to ground, so that a voltage V obtained by dividing Vcc by resistance is obtained from the contact 2. On the other hand, since terminal 4 is connected to ground, contact 3
When the terminal 4 contacts the terminal 4, the OV limit point detection signal LL is output.

The first method is to set the output of contact 2 at the time when this signal LL is detected as the lowest value Vmin of the sen signal.

Ru. Thereafter, the minimum value (offset) Vmin is subtracted from the current value V obtained from the contact point 2 to obtain the displacement amount (actual opening degree). The drawback of this method is that the accuracy of the obtained absolute value is poor because a certain degree of width must be allowed for the mechanical limit point.

For this reason, currently the second method is mainstream, in which the lowest value appearing in the output V of contact 2 is sequentially updated and stored without using a lower limit rim switch using contact 3 and terminal 4.

However, with this method, if an abnormally low value that cannot occur in normal operation is stored as Vmin, that value will never be updated again, so all subsequent absolute values will contain abnormal errors. There are some disadvantages.

The present invention makes it possible to obtain highly accurate absolute value output by improving the second method, and its feature is that the lowest value of the output obtained from the mechanical position sensor is updated sequentially. In a sensor processing method that calculates the absolute value of the displacement at each point in time by storing the minimum value in a memory circuit and subtracting the minimum value from the current value of the sensor output, the structure of the position sensor is determined by a mechanical lower limit. A limit point detection signal shall be generated, and when the absolute value at the time the limit point detection signal is generated exceeds a preset reference value,
The purpose is to update the contents of the memory circuit with the current value at that time.

The present invention will be described in detail below with reference to the embodiment shown in FIG. In the figure, 10 is the minimum value νmin mentioned above.
A circuit 11 compares the current value ■ with the lowest value Vmin, and if V < Vmin, turns on the switch 12 and stores the contents of the storage circuit 10 using the current value V (
A comparator 13 updates Vmin) at each time point.
This is a difference detector that calculates Vmin and obtains an absolute value. These circuits 10 to 13 are necessary elements when executing the conventional second method, and with only these circuits, the lowest value V in the memory circuit 10 can be reduced.
min is updated only in the lower direction due to lightning. Therefore, if an abnormally low value is stored, the output of the comparator 11 will then become >Vmin, and the contents of the storage circuit 10 will never return to within the normal value range.

In this example, a switch 14, a difference detector 15, and a comparator 16 are provided to make this possible. The switch 14 is normally turned to the solid line side, and the two-man power of the difference detector 15 is set to the current value V.
(therefore, the difference output DIF is 0), but when it receives the limit point detection signal LL (=OV) in Fig. 2, it switches to the dashed line side, and the two manual forces of the difference detector 15 are set to the current value ■ and the minimum value Vm.
In.

As a result, the difference detector 15 outputs a difference DIF=V-Vmin
Calculate. The current value V at the time when the signal LL is generated is usually a value close to the minimum value Vmin. Therefore, if the memory circuit 10 is operating normally, the differential output DIF is a small value.
If the lowest value Vmin is abnormally low (minimum value is O), the difference output becomes large, and the output of the comparator 16 becomes
>REF and turns on the switch 12. As a result, there is a relationship of V>Vmin. Further, the reference value REF used by the comparator 16 is a constant value set assuming the minimum value that Vmin can take in normal operation from a mechanical standpoint. Furthermore, since FIG. 1 is a functional representation, its configuration can be modified in various ways. For example, the output (V - V+++in) of the difference detector 13 is connected to the signal LL by the switch 14.
The difference detector 15 can be omitted if the difference detector 15 is led to the DIF human power of the comparator 16 only when it occurs.

As described above, according to the present invention, the absolute value of the displacement amount can be determined with high accuracy from the output of a mechanical position sensor such as a throttle sensor.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG. 2 is an explanatory diagram of a throttle sensor. In the figure, 2 is a current position detection contact, 3 is a lower limit position detection contact, 10 is a minimum value storage circuit, 11.16 is a comparator, 12
．． 14 is a switch, and 13.15 is a difference detector.

Claims (1)

[Claims] The lowest value of the output obtained from the mechanical position sensor is stored in a memory circuit while being updated sequentially, and the absolute value of the amount of displacement at each point in time is determined by subtracting the lowest value from the current value of the sensor output. In the sensor processing method, the structure of the position sensor is such that a limit point detection signal is generated at a mechanical lower limit, and the limit point detection signal is a force (the absolute value at the time of generation exceeds a preset reference value). A sensor processing method characterized in that, at a time, the contents of the memory circuit are updated with a current value at that time or a constant value.