JP2000321094A - Detecting apparatus for neutral position of potentiometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a detecting apparatus by which the neutral position of a potentiometer and the neutral position of a shaft can be made to agree with good accuracy. SOLUTION: In this detecting apparatus, the moving terminal of a potentiometer is moved so as to adjust a resistance value (Step S1), the digital value N of a potential V at the moving terminal, which is digital-converted by an analog/ digital(A/D) converter via an input/output(I/O) part and a reference value Ns corresponding to, e.g. a neutral position which is stored in advance are compared by a CPU, and whether they agree or not is judged (Step S2 to Step S4). When a judged result is YES, a reporting operation is performed by a reporting part, i.e., a character 'neutral' is displayed by a display, and an LED is turned on (Step S6). Then, it is judged that the moving terminal of the potentiometer is in a neutral position (Step S7), it is arranged that the reporting operation by the reporting part is not interrupted, and the potentiometer is attached to a prescribed shaft (Step S8).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a neutral potentiometer for detecting the neutral position of a potentiometer which is mounted so that its neutral position coincides with the neutral position of the rotary shaft and which is used for detecting the rotation angle of the rotary shaft. Related to the device.

[0002]

2. Description of the Related Art In a forklift, a potentiometer is usually used in order to make the rotation angle of a steered wheel coincide with the rotation angle of a steering wheel. In this case, the rotation of the steered wheels is controlled by the actuator such that the rotation angle detected by the potentiometer on the steering wheel is set as the target value and the rotation angle detected by the potentiometer on the steered wheels is equal to the target value. .

In order to perform such control, it is necessary that the neutral position of the steering wheel and the neutral position of the steered wheels coincide with each other. Generally, the neutral position of the rotating shaft of the steering wheel and the neutral position of the steered wheels are required. The neutral position of the rotating shaft,
A potentiometer is attached to each rotating shaft so that the neutral position of each potentiometer matches.

For this purpose, it is necessary to detect the neutral position of the potentiometer, that is, to detect the center position. Conventionally, a voltage is applied to both ends of the potentiometer to measure the resistance value.
A position where the resistance value becomes 1/2 is calculated, and the calculated position is set as a neutral position.

[0005]

However, in such a conventional neutral detection, the measured resistance value is inaccurate, and a deviation generated when the potentiometer is attached to the rotating shaft is caused by the above-mentioned factors. Because the neutral position of each rotary shaft and the neutral position of the potentiometer do not match exactly,
As described above, even if the rotation of the steered wheels is controlled such that the rotation angle detected by the potentiometer on the steered wheels is set to the target value while the rotation angle detected by the potentiometer on the steering side is set as the target value, the steering wheels must be accurately matched. There was a problem that can not be.

When controlling the rotation of a steered wheel so that the rotation angle detected by a potentiometer on the steered wheel side coincides with the target value, the detected rotation angle and the like are digitized and processed. There is a possibility that the rotation angle of the steered wheels cannot be accurately matched with the target value due to the influence of the performance.

An object of the present invention is to enable the neutral position of the potentiometer to accurately coincide with the neutral position of the rotary shaft.

[0008]

In order to solve the above-mentioned problems, the present invention relates to a potentiometer which is mounted so that the neutral position of the rotary shaft coincides with the neutral position, and detects the rotation angle of the rotary shaft. A potentiometer neutral detecting device for detecting a neutral position of the potentiometer prior to mounting; a detecting unit for applying a voltage to both ends of a target potentiometer to detect a potential of a movable terminal of the potentiometer; A comparison unit that compares a detection potential obtained by the detection unit when the position of the terminal is moved with a reference potential corresponding to a preset neutral position, and when the comparison result by the comparison unit indicates that both match, this fact is indicated. And a notifying unit for notifying.

According to this configuration, when the position of the movable terminal of the potentiometer is moved, the detection potential of the movable terminal detected by the detection unit is compared with the reference potential by the comparison unit. When they match, the notification unit notifies. At this time, by setting the reference potential to the potential when the movable terminal of the potentiometer is at the center, it is understood from the notification by the notification unit that the movable terminal of the potentiometer is at the neutral position.

Therefore, the notification by the notification unit indicates that the detection potential of the movable terminal of the potentiometer by the detection unit matches the reference potential, and that the movable terminal of the potentiometer is at, for example, the neutral position. By attaching the potentiometer to the rotary shaft while keeping the neutral position, the neutral position of the potentiometer and the neutral position of the rotary shaft can be accurately matched.

The present invention further comprises a conversion unit for performing analog / digital conversion of the detection potential of the detection unit and the reference potential, wherein the comparison unit compares the digital value of the detection potential with the digital value of the reference potential. Features. In this case, the conversion unit is not dedicated to the detection of the neutrality of the potentiometer, but is also used in the actual use state, thereby performing the neutralization detection of the potentiometer including the performance at the time of analog / digital conversion by the conversion unit. And the neutral position of the potentiometer can be accurately matched with the neutral position of the rotating shaft.

Further, the present invention is characterized in that the notifying section has a visual notifying function. Further, the notification unit may have an auditory notification function. By doing so, visual or audible notification by the notification unit
The operator can reliably grasp that the potentiometer is at the neutral position.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a potentiometer used for steering control of a forklift and rotation of a steered wheel will be described with reference to FIGS. However, FIG. 1 is a block diagram,
FIG. 2 is a flowchart for explaining the operation, and FIG. 3 is a block diagram in a use state.

As shown in FIG. 1, both ends 1a and 1b of a potentiometer 1 composed of a variable resistor are connected to a positive terminal (+ V) and a negative terminal (G) of a DC power supply 4 built in a neutral detector 2.
ND) and the movable terminal 1c of the potentiometer 1
Is converted via an input / output unit (hereinafter, referred to as I / O) 6 constituting a detection unit together with the DC power supply 4 into an analog / digital converter (hereinafter, analog / digital conversion is referred to as A / D conversion). / D conversion) 8 and this A
The potential signal is converted by the / D converter 8 into an 8-bit digital signal.

The digital value N of the potential V of the movable terminal 1c output from the A / D converter 8 is input to the CPU 10, and the digital value N is stored and set in advance in a storage unit such as a built-in memory of the CPU 10. Is compared with a reference value Ns which is a digital value of the reference potential corresponding to the neutral position thus set.
Here, the comparison processing by the CPU 10 corresponds to a comparison unit.

At this time, in order to accurately detect the neutral position of the potentiometer 1, the reference value Ns is set to, for example, the digital value of the potential when the movable terminal 1c of the potentiometer 1 is set to an intermediate position having a resistance value of 50%. I just need. In addition, if necessary, the digital value of the potential signal when the movable terminal 1c is adjusted to a position where the resistance value of the desired% is obtained,
The reference value Ns may be used.

As described above, if the digital value N of the potential V of the movable terminal 1c of the potentiometer 1 and the reference value Ns match within a predetermined allowable error range as a result of the comparison by the CPU 10, a notification is made via the I / O 6. A control signal is output by the unit 12 to notify the user of the change. The control signal causes the display 12a of the notification unit 12 to display "neutral" characters, turns on the LED 12b, and moves the movable terminal 1c of the potentiometer 1 to the neutral position. Is notified.

Next, the neutral detection operation of the potentiometer 1 will be described with reference to the flowchart of FIG. Now, as shown in FIG. 2, when the movable terminal 1c of the potentiometer 1 is moved to adjust the resistance value R (see FIG. 1) (step S1), the A / D converter 8 sends the signal to the A / D converter 8 via the I / O 6. The input potential V of the movable terminal 1c changes (Step S).
2), the potential V digitally converted by the A / D converter 8
Is changed (step S3).

The CPU 10 determines whether or not the reference value Ns stored in advance and the digital value N from the A / D converter 8 match (step S4). Since it can be determined that the movable terminal 1c of the potentiometer 1 is not at the neutral position,
2 is not issued (step S5), and the process returns to step S1.

On the other hand, if the decision result in the step S4 is YES, the notification by the notification section 12, that is, the display 1
The display of the character "neutral" by 2a and the lighting of the LED 12b are performed (step S6), it is determined that the detection of the neutral position of the movable terminal 1c of the potentiometer 1 is completed (step S7), and the notification of the notification unit 12 is interrupted. The potentiometer 1 is mounted on the rotating shaft of the steering wheel or the steered wheels without any adjustment (step S8), and then the operation ends.

The rotation control of the steered wheels after the potentiometer 1 thus detected as neutral is attached to the steering and the rotating shaft of the steered wheels will be briefly described with reference to FIG.

FIG. 3 is a block diagram of a steering wheel rotation control system. In this embodiment, the control device of the rotation control system is used as the neutral detection device 2 shown in FIG. Potentiometers 1S and 1T are attached to the rotation shaft of the wheel 23 to detect the rotation angles, respectively. The rotation angle of the rotation shaft 22 detected by the potentiometer 1S on the steering 21 side is converted into an A / D converter via the I / O6. The rotation angle is converted into an 8-bit digital value by the A / D converter 8 and input to the CPU 10. Here, the rotating shaft 2
The rotation angle of 2 is expressed by the number of rotations, for example, leftward and rightward (or advance direction and delay direction) with respect to the neutral position of the rotation axis. Incidentally, reference numeral 24 denotes a knob provided for operating the steering 21.

The opening and closing of the electromagnetic valve 26 is controlled by an opening and closing control signal output from the CPU 10 in accordance with the turning angle of the rotating shaft 22 of the steering 21, and the orbit roll 29 connected to the oil tank 27 via the pump 28 is controlled. Is supplied to the electromagnetic valve 26 to drive the cylinder 30 to rotate the rotating shaft of the steering wheel 23. At this time, since there is oil leakage in the orbit roll 29 and the like, the amount of oil to be supplied to the cylinder 30 by the opening and closing control of the electromagnetic valve 26 does not match the amount of oil supplied to the operation.

Then, the rotation angle of the rotating shaft of the steered wheel 23 is detected by the potentiometer 1T on the steered wheel 23 side, and this is fed back to the CPU 10 via the I / O 6 and the A / D converter 8, and the potentiometer on the steered wheel 23 side. The opening / closing control of the electromagnetic valve 26 is performed by the potentiometer 1T so that the rotation angle of the rotating shaft of the steered wheel 23 coincides with the target value using the detection value by 1S as the target value.

Therefore, according to the above-described embodiment, from the notification by the notification unit 12, the detected potential of the movable terminal 1c of the potentiometer 1 matches the reference potential, and the movable terminal 1c of the potentiometer 1 is, for example, at the neutral position. By attaching the potentiometer 1 to the rotary shaft 22 or the like of the steering 21 in the forklift, the neutral position of the potentiometer 1 and the neutral position of the rotary shaft 22 etc. Accurate matching can be achieved.

Further, since the control device used in the rotation control system of the steered wheels 23 of the forklift is used as it is as the neutral detection device 2, it is possible to detect the neutral in the same condition as the actual use condition in the rotation control. Therefore, due to the influence of the performance of the A / D converter 8, it is possible to eliminate the deviation between the detected neutral position of the potentiometers 1S and 1T and the neutral position indicated by the potentiometers 1S and 1T during rotation control of the steered wheels 23. Thus, more accurate neutral detection and rotation control can be performed.

The notifying section is not limited to the one having the function of notifying visually as described above, but may be constituted by an element having an audible notifying function such as a buzzer or a voice synthesizing circuit. Absent.

In the above-described embodiment, the case where the potentiometer 1 is attached to the neutral position of the rotating shaft of the steering 21 or the like of the forklift in such a manner as to match the neutral position is described. Even when the neutral position is detected, the present invention can be implemented in the same manner, and the same effect as the above-described embodiment can be obtained.

Further, the present invention is not limited to the above-described embodiment, and various changes other than those described above can be made without departing from the gist of the present invention.

[0030]

As described above, according to the first aspect of the present invention, from the notification by the notification unit, the detection potential of the movable terminal of the potentiometer by the detection unit matches the reference potential,
Since the movable terminal of the potentiometer is at the neutral position, the potentiometer is attached to the rotating shaft while the notification by the notification unit is not interrupted, and the neutral position of the potentiometer and the neutral position of the rotating shaft are accurately matched. It becomes possible.

According to the second aspect of the present invention, the conversion unit is not dedicated to neutral detection of the potentiometer,
By also using the one used in the actual use condition, the neutralization of the potentiometer including the performance at the time of analog / digital conversion by the conversion unit can be detected.
The neutral position of the potentiometer can be accurately matched with the neutral position of the rotary shaft.

According to the third and fourth aspects of the present invention, the operator can be reliably informed that the potentiometer is at the neutral position, for example, by visual or audible notification by the notification unit.

[Brief description of the drawings]

FIG. 1 is a block diagram of one embodiment of the present invention.

FIG. 2 is a flowchart for explaining the operation of the embodiment of the present invention;

FIG. 3 is a block diagram in a use state of the embodiment of the present invention;

[Explanation of symbols]

 1, 1S, 1T potentiometer 2 Neutral detection device 4 DC power supply (detection unit) 6 I / O (detection unit) 8 A / D converter (conversion unit) 10 CPU (comparison unit) 12 notification unit

Claims (4)

[Claims] 1. A potentiometer which is mounted so that its neutral position coincides with a neutral position of a rotary shaft and detects a rotation angle of the rotary shaft, wherein the potentiometer detects a neutral position of the potentiometer prior to mounting. In the neutral detection device, a detection unit that applies a voltage to both ends of a target potentiometer to detect a potential of a movable terminal of the potentiometer, and sets a potential detected by the detection unit when the position of the movable terminal is moved to a preset value. A comparison unit for comparing a reference potential corresponding to the set neutral position, and a notifying unit for notifying when both match as a result of the comparison by the comparison unit. Detection device. 2. The apparatus according to claim 1, further comprising a conversion unit configured to perform analog-to-digital conversion of the detection potential of the detection unit and the reference potential, and wherein the comparison unit compares the detection potential and a digital value of the reference potential. Item 4. A neutral detector for the potentiometer according to Item 1. 3. The potentiometer neutral detection device according to claim 1, wherein the notification unit has a visual notification function. 4. The potentiometer neutral detection device according to claim 1, wherein the notifying unit has an audible notifying function.