KR920008708B1 - Automatic steering system for forklift - Google Patents

Abstract

In an automatic steering controller of a forklift to get precise steering, an high frequency induction wire is laid under the ground of the forklift travel road and signals are processed by a pick-up sensor, an encoder and a potentiometer. The steering controller consists of a pick sensor, plural filters, A/D transformer, a unreuersing amplifier, a derailment comparator, a dead zone generator, a current amplifier, a logic section, a derailment signal generator, an encoder, a direction detector, a frequency/ voltage transformer and stop signal generator.

Description

Forklift Automatic Steering Controller

1 is a block diagram of an automatic steering controller of a forklift according to the present invention.

Figure 2a is a detailed circuit diagram of a dead zone generator to be applied to the present invention.

b is input waveform waveform which is the standard of dead zone generator.

c is a waveform diagram showing the difference between the input voltage and the output voltage of the dead zone generator.

Figure 3a is a detailed circuit diagram of the driving direction discriminator applied to the present invention.

b is a waveform diagram at the time of the forward driving signal of the driving direction toilet,

c is a waveform diagram at the time of reverse driving signal generation of the driving direction discriminator.

4 is a general configuration diagram of a forklift automatic steering controller applied to the present invention.

* Explanation of symbols for the main parts of the drawings

1, 1 ', 30, 30': Low pass filter 2, 2 ', 40, 40': High pass filter

3, 3 ', 50, 50': band pass filter 4, 4 ', 60, 60': AC / DC converter

5, 5 ', 70, 70': Non-inverting amplifier 6, 6 ': Derail comparator

7 Dead Zone Generator 8 Current Amplifier

9: logic unit 10: derailment signal generator

11, 11 ': Relay 12: Encoder

13: driving direction discrimination circuit 14: frequency / voltage converter

15: Stop signal generator 16, 16 ', 18, 18': Analog switch

17 potentiometer

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic steering controller of a forklift, and in particular, embeds a high frequency induction line in a forklift driving path and processes signals by a pickup sensor, an encoder, a potentiometer, etc., which detects the position of the high frequency induction line. The present invention relates to an automatic steering controller of a forklift that automatically controls a steering motor of a single-axis driven forklift to achieve accurate driving along a guide line.

In conventional forklifts that operate in manual warehouses, when the narrow space between the racks of manual warehouses and the straight route are repeatedly operated, there is a risk of frequent collisions with racks because of manual operation. There was an economic loss by damaging the forklift and rack accordingly, there was a variety of problems, such as a safety accident may occur to the operator, resulting in a decrease in work efficiency.

In order to solve this problem, conventionally, forklift was developed by operating a computer program and by introducing an automated system by a computer, the forklift was automatically operated according to the program, and warehouse cleaning was performed. However, when the forklift is repeatedly operated for the long time without the automatic steering means, the forklift is inevitably gradually deviated from the driving path due to the geographical effect, so that the amount of deviation is artificially There was an inconvenience to be corrected from time to time, and when the correction time is over, the forklift will have a problem that it will collide with obstacles around the road.

Accordingly, the present invention has been made in view of these various problems, and an object of the present invention is to add an automatic steering function to a forklift that repeatedly runs a narrow space between the rats and a straight route, thereby eliminating work hazards and working. The present invention provides an automatic steering controller of a forklift that aims to prevent economic losses by improving efficiency and preventing collision between the forklift and the rack.

In order to achieve the above object, the automatic steering controller of the forklift according to the present invention includes a pickup sensor for detecting a position of a high frequency induction line, a low pass filter that blocks high frequencies, a high pass filter that blocks low frequencies, and a frequency used only. A band pass filter for passing through, an AC / DC converter for converting an AC signal passing through the band pass filter into a DC signal for simplifying signal processing, a non-inverting amplifier for amplifying the signal converted into DC, and a front or rear sensor A derail comparator for determining whether there is an induction path between them, a dead zone generator for removing a small error signal so as to prevent vibration of the vehicle body, and amplifying a final signal from which a small error signal has been removed by passing through the dead zone generator Converts the comparison signal of the current amplifier inputted by the servo command of the steering motor and the derailment comparator into a digital signal The logic unit to deactivate the forklift when the forklift is derailed on the driving path, and a derailment signal generator which cuts off the driving motor, an encoder connected to the driving motor by a belt, and an output of the encoder. Automatic steering function consisting of a driving direction discriminator for discrimination, a frequency / voltage converter for converting a frequency into a voltage to shut off the steering motor when the forklift is stopped, and a stop signal generator for generating a signal for shutting off the steering motor. It is characterized by improving the work efficiency and preventing safety accidents.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

1 is a block diagram of an automatic steering controller of a forklift according to the present invention, FIG. 2a is a detailed circuit diagram of a dead zone generator applied to the present invention, and FIG. 2b is an input voltage waveform diagram which is a reference of the dead zone generator. 2C is a waveform diagram showing the difference between the input voltage and the output voltage of the dead zone generator. 3A is a detailed circuit diagram of the driving direction discriminator applied to the present invention, and FIG. 3B is a waveform diagram when the forward traveling signal is generated by the driving direction discriminator, and FIG. 3C is a waveform when the backward driving signal is generated by the driving direction discriminator. 4 is a general configuration diagram of an automatic steering controller of a forklift applied to the present invention.

In FIG. 4, reference numeral 21 denotes an induction line through which a high frequency current flows, and a pair of pickup sensors 80 and 80 'are installed at the front, left and right sides of the forklift with the induction line 21 interposed therebetween. Sensors 90 and 90 'are provided at the rear left and right. The driving motor 22 which provides the driving force to the forklift is connected to the encoder 12 through the belt 23 'so that the encoder 12 corresponds to the forward and reverse when the driving motor 22 rotates forward and backward. The output signal is applied to the driving direction discriminator 13 which will be described later in detail to determine whether the forklift is moving forward or backward.

On the other hand, the potential sequence 17 for measuring the voltage by the zero method is connected to the steering shaft 24 by a wire 23, the steering wheel 25 is coupled to the steering shaft 24 through the lever 35. The steering shaft 24 obtains a driving force from the steering cylinder 26.

Therefore, when the steering shaft 24 is rotated to the left by the driving force of the steering cylinder 26, a negative (-) signal is output from the potential sequence 17 connected by the wire 23 to the steering shaft 24. When it rotates to the right side, a positive signal is output.

The pickup sensors 80, 80 ', 90, 90', the encoder 12 and the potentiometer 17 are connected to the sensor board 27 through a cable 26, and the output terminal of the sensor board 27 is looped. It is connected to the servo board 29 which controls the steering motor 28 through the cable 26 '. The sensor board 27 is configured to be an automatic steering controller according to the present invention to be described later, the steering motor 28 is to be controlled by a signal output from the automatic steering controller through the servo board 28 will be.

That is, the automatic steering controller outputs a control signal to control the steering motor 28, and the steering motor 28 applies hydraulic pressure to the steering cylinder 26 according to the control amount, and the steering cylinder 26. ) Drives the steering shaft 24 to which the steering wheel 25 is connected according to the size of the hydraulic pressure so that the forklift is automatically steered.

Meanwhile, the steering wheel 31 and the steering motor 28 are each provided with a clutch 32 and the clutch 32 has a structure connected to the hydraulic motor 33. Therefore, when the user operates the clutch 32, the hydraulic motor 33 applies hydraulic pressure to the steering cylinder 26 through the distributor 34, and the cylinder 26 drives the steering shaft 24. By displacing the steering wheel 25 connected to the shaft 24, it is possible to manually steer the forklift.

The following describes the automatic steering controller according to the present invention in detail with reference to the drawings.

In FIG. 1, (1) (1 ') 30 and 30' are pickup sensors 80, 80 ', 90, which detect the position of the high frequency induction line 21 embedded in the driving path of the forklift. 90 ') is a low pass filter (LPR: Low pass filter) that cuts the high frequency, (2) (2') (40, 40 ') is a function for detecting the position of the high frequency induction line 21 as described above It is a high pass filter (HPF: High pass filter) that fills the low frequency of the pickup sensor (80, 80 ', 90, 90'), and (3) (3 ') (50) (50') It is a band pass filter (BPF: Bandpss filter) that passes only the currently used frequency of the pickup sensor (80, 80 ', 90, 90').

That is, the low pass filter, the high pass filter, the band pass filter, etc., the signal of any frequency band is lost as much as possible in the 4-terminal network (which can be calculated by knowing the 4-terminal constant of the input terminal and the output terminal). Pass without, and attenuate other frequency bands.

Also, (4) (4 ') 60 (60') is an AC / DC converter for converting an AC signal passing through the band pass filter (3) (3 ') 50 (50') into a DC signal. (5) (5 ') (70) (70') are non-inverting amplifiers for amplifying the DC-converted signal, and (6) (6 ') are the induction paths between the front or rear sensors. Derail comparator for determining whether or not, (12) is an encoder attached to the shaft of the driving motor 22 using a belt 23 ', (13) is forward or using the output of the encoder 12 It is a driving direction discriminator for reversing.

In addition, (7) is a dead zone generator for removing a small error signal caused by the vehicle body vibration, (8) amplifies the final signal from the dead zone generator 7 to steer the motor 28 (10) is a derailment signal generator that generates a derailment signal using the signal of the logic unit 9 when the forklift derails on the driving path, and (14) the encoder A frequency-to-voltage converter for converting the frequency output from (12) into a voltage, (15) is a stop signal generator for generating a stop signal of the steering motor when it is determined that the forklift is stopped by the output of the encoder 12 On the other hand, (17) is a potentiometer 17 (Potentiometer) for measuring the voltage by a zero method, it is connected to the steering shaft 24 (Steering Shaft) by a wire (23) When the steering wheel 31 is turned to the left, the output Giant Creative (-) and the composition to be polarized.

In addition, the pick-up sensor secures four sensors 80, 80 ', 90, 90' to the front and rear of the vehicle body, and the center line of the sensor and the center line of the forklift coincide, and the four sensors are arranged to form a rectangle.

Referring to the operation of the automatic steering controller of the forklift according to the present invention configured as described above are as follows.

First, when the forklift travels forward, two front sensors, that is, a front left sensor 80 and a front right sensor 80 'are used.

The signal detected by the front left sensor (80) is input to the high pass filter (2) after the high frequency is blocked by the low pass filter (1) through a pre-amplifier (not shown), the high pass In the filter 2, the low frequency is cut off, and the rest other than the frequency band used for the guide line 21 embedded in the forklift path is removed, and the rest other than the frequency currently used by the band pass filter 3 is removed. Remove all.

Subsequently, the signal of the AC component passing through the bandpass filter 3 passes through the AC / DC converter 4 to simplify the signal processing, and the non-inverting amplifier 5 amplifies the converted DC signal.

On the other hand, the signal detected by the front right sensor (80 ') is input to the high pass filter 40 after the high frequency is blocked by the low pass filter 30 through a preamplifier (not shown), the high pass filter ( In 40), the low frequency is cut off, and the rest of the frequency band is removed from the guide line 21 embedded in the forklift driving path, and the rest of the frequency other than the frequency currently used by the band pass filter 50 is removed.

Subsequently, the signal of the AC component passing through the bandpass filter 50 passes through the AC / DC converter 60 to be converted into a DC signal capable of driving a motor, and is converted by the non-inverting amplifier 70. DC signal is amplified.

Thus, when the difference between the front left signal and the front right signal of the forklift passing through each of the non-inverting amplifiers 50 and 70 is expressed by a formula, the magnitude of the front left signal is FL, and the magnitude of the front right signal is FR. In this case, the error signal DELTA F = FL-FR.

The forward driving offset is added to the error signal obtained by ΔF, and the forward driving offset is added to the error signal by the analog switch 16 to be combined with the output signal of the potentiometer 17 to become a final signal. The final signal passes through the dead zone generator 7.

That is, since the vehicle body vibrates when the motor responds to the small error signal, the final signal passes through the dead zone generator 7 to remove the small error signal that causes the vibration. As shown in FIG. 2 and FIG. 2C, the difference (FIG. 2C) between the input signal Vi and the output signal Vo is eliminated.

The final signal passed through the dead zone generator 7 is input to the servo command of the steering motor 28 after the current is amplified by the current amplifier 8, and passes through the respective non-inverting amplifiers 50 (70). When the error signal ΔF for the front left and right signals exceeds a certain level, the derail comparator 6 determines whether there is an induction path between the front or rear sensors, and determines the analog switch 16 '. When the input to the logic unit 9 through the two state or level possible in the logic unit 9, i.e., '0' or '1' and then the derailment signal generator 10 outputs the output of the logic unit 9. To generate a derailment signal.

Accordingly, when the derailment signal is generated, the forklift travels by being applied to the driving motor 22 through the relay 11 to block the driving motor 22 and generating a derailment alarm through a buzzer or the like so that an operator can judge it. Derailing from the furnace will prevent collisions.

Next, a case where the forklift travels backward is described.

When the forklift travels backward, unlike the case of the forward driving described above, four front and rear sensors, that is, the front left sensor 80, the front right sensor 80 ', the rear left sensor 90 and the rear right All of the sensors 90 'are used to detect the angle of the vehicle body and the guide line 21 to improve the reliability of tracking during the reverse driving.

As for the forward driving of the forklift, the same goes through the respective filter.

That is, the signal detected by the rear left sensor 90 passes through a preamplifier (not shown) and passes through a low pass filter (1 '), a high pass filter (2'), and a band pass filter (3 '). After removing all the rest except the frequency, it is converted into a DC signal by the AC / DC converter 4 'and amplified by the non-inverting amplifier 5', and the signal detected by the rear peripheral sensor 90 'is not shown. After passing through the preamplifier, the low pass filter (30 '), the high pass filter (40') and the band pass filter (50 '), and remove all the rest other than the current frequency, the AC / DC converter ( 60 ') is converted into a DC signal and amplified by the non-inverting amplifier 70'.

The difference between the rear left signal and the rear right signal of the forklift passing through each of the non-inverting amplifiers 5 'and 70' is referred to as BL and the magnitude of the rear right signal is referred to as BL. In the case of BR, the error signal DELTA B = BL-BR becomes.

Accordingly, it is possible to detect the angle of the vehicle body and the guide line 21 to improve the tracking reliability when driving backward. When the angle between the guide line 21 and the vehicle body is ΔA, ΔA = ΔB-ΔF = (BL It is obtained by the formula -FL) + (FR-BR).

In this case, the final error signal is obtained by adding the appropriate weights to each using the guide line 21, the angle ΔA of the vehicle body, and the error signal ΔB of the rear sensor, and this is the same as when driving forward. Is entered.

That is, the signal in which the rear travel offset is added to the error signal? B of the rear sensor is combined with the output signal of the potentiometer 17 by the analog switch 18 to become the final signal, and this final signal is the dead zone generator 7. After passing through the dead zone generator 7, the small error signal causing the vibration of the vehicle is removed, and the current is amplified by the current amplifier 8 and input to the servo command of the steering motor 28.

In addition, when the error signal ΔB for the rear left and right signals passing through each of the non-inverting amplifiers 5 'and 70' is equal to or higher than a predetermined level, the derail comparator 6 'guides the front or rear sensor. It is determined whether there is a furnace, and when the determined signal is inputted to the logic unit 9 through the analog switch 18 ', the logic unit 9 converts the digital signal and then derails the derailment signal generator 10. Signal is generated and the derailment signal is applied to the driving motor 22 through the relay 11 to shut off the driving motor 22 and generate an alarm sound through a buzzer or the like for the operator to judge. Derailing from the roadway will prevent collisions.

On the other hand, the forward driving steering signal input from the encoder 12 is transmitted to the servo command by the driving direction discrimination circuit 13 when the forklift is driven forward, and the backward driving steering signal is the servo command when the forklift is driven backward. In order to be transmitted, it is possible to select automatically using the analog switch 16 when driving forward and the analog switch 18 when driving backward. When the forklift is stopped, the frequency is output by using the output of the encoder 12. When a signal for converting the steering motor 28 to the voltage for blocking the steering motor 28 from the voltage conversion unit 14 and stopping the steering motor 28 by the stop signal generator 15 is generated, the signal is relayed 11 '. By cutting the steering motor 28 through) to minimize power consumption.

As shown in FIG. 3A, the driving direction discrimination circuit 13 has D- with two inputs D and CLK and two outputs Q and Q, which are a kind of digital circuit capable of accumulating information. It consists of flip-flop 100, two comparators COM1 and COM2, and resistors R1 and R2. In the forward driving of the forklift, waveform A and waveform B shown in FIG. After the waveform is outputted, the output Q from the D-flip-flop 100 input to the non-inverting input terminal (+) and the reference voltage input to the inverting input terminal (-) are compared in the comparator COM1. A forward signal of +12 V is transmitted to the servo command by the analog switch 16, and during backward driving of the forklift, waveforms such as waveform A and waveform B shown in FIG. The output Q from the D-flop flop 100 input to the terminal (+) and the reference voltage input to the inverting input terminal (-) are comparators (COM). After comparison in 2), the reverse signal of + 12V is transmitted to the servo command by the analog switch 18.

On the other hand, in the automatic steering controller of the forklift of the present invention, attention should be paid to the polarity of the sensor, the encoder 12, the potentiometer 17 and each amplifier, and the algorithm proposed in the present invention uses a microprocessor to configure the controller. The same applies to the case.

As described above, according to the automatic steering controller of the forklift according to the present invention, the automatic steering function is added to the forklift, thereby reducing the damage of the human life and preventing economic loss, and at the same time, improving the work efficiency.

Claims (7)

A pickup sensor for detecting the position of the high frequency induction wire, a low pass filter that blocks the high frequency, a high pass filter that blocks the low frequency, a band pass filter that passes only the used frequency, and an AC signal passing through the band pass filter to drive the motor. An AC / DC converter for converting a DC signal, a non-inverting amplifier for amplifying the DC signal, a derail comparator for determining whether there is an induction path between the front or rear sensors, and vibration of the vehicle body. A dead zone generator for removing a small error signal, a current amplifier for amplifying the final signal from which the small error signal has been removed by passing through the dead zone generator, and inputting the servo signal to the servo command of the steering motor; and a comparison signal of the derail comparator. Detachment signal is generated when the forklift is derailed from the driving path Derailment signal generator to block the row motor, encoder connected to the drive motor shaft by a belt, driving direction discriminator to determine forward and backward using the encoder output, and to stop the steering motor when the forklift is stopped And a frequency / voltage converter for converting a frequency into a voltage, and a stop signal generator for generating a signal for shutting off the steering motor. The method of claim 1, wherein the derailment comparator determines whether there is a guide line between the front or rear sensors using signals detected by the front left sensor, the front right sensor, the rear left sensor, and the rear right sensor. Forklift automatic steering controller. The forklift automatic steering controller of claim 1, wherein the dead zone generator is configured to remove a small error signal by applying a final signal obtained by adding the output signal of the potentiometer and the signal of the front left and right sensors to which the forward driving offset is added. . The forklift automatic steering controller according to claim 1 or 3, wherein the dead zone generator prevents vibration of the vehicle body by removing a small error signal. The forklift automatic steering controller according to claim 1, wherein the signal generated by the derailment signal generator is applied to the motor through a relay so that the traveling motor is blocked and a derailment alarm is generated through a buzzer or the like. The forklift automatic steering controller according to claim 1, wherein the driving direction discrimination circuit is configured to automatically select the forward and backward steering signal by using an analog switch so as to be transmitted as a servo command. The automatic steering controller of claim 1, wherein the stop signal generator blocks a steering motor by applying a signal for blocking the steering motor to the motor through a relay.

Images