JP2003182991A - Controller for reach type forklift truck - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a controller that can provide high precision attitude control, antislip control and automatic suspension control. <P>SOLUTION: Encoders 22 and 23 for both front wheels detect rotating speeds Nl and Nr of both front wheels respectively. A derivation part 26 arithmetically derives a left-right wheel diameter ratio Klr from the rotating speeds Nl and Nr of both front wheels, a steering angle θ of a driving wheel by a potentiometer 24, and arrangement dimensions of both front wheels and driving wheel. With the use of the left-right wheel diameter ratio Klr, a control part 27 controls a motor driver 21 and a travel motor 20 to offer, for example, antislip control considering tire wear of each of the front wheels 6l and 6r. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention includes a vehicle body having a pair of left and right front wheels and rear wheels, a rear motor rotatably driving the rear wheels for traveling, and a steering device for rotating the rear wheels for steering. Type forklift control device.

[0002]

2. Description of the Related Art Generally, a reach type forklift is constructed as shown in FIGS. That is, straddle arms 3 are projectingly fixed to the left and right ends of the front part of the vehicle body 2 of the reach type forklift 1, respectively, and a fork 4 which is lifted and lowered by a lift cylinder (not shown) is provided between the straddle arms 3. Mast 5 to guide
Is erected so that it can be moved back and forth. Left and right front wheels 6l and 6r are rotatably attached to both straddle arms 3, and a drive wheel 7 as one rear wheel is attached to the lower rear portion of the vehicle body 2 and supports the vehicle body 2. Two caster wheels 8 that follow the progression of 2 are attached.

Further, as shown in FIG. 3, the vehicle body 2 is provided with various hydraulic operating levers 9 for operating the mast 5 and the forks 4, and an accelerator for rotationally driving the drive wheels 7. 10 is provided and a steering handle 11 for steering is provided, and the turning traveling is performed by controlling the direction of the drive wheels 7, that is, the so-called steering angle according to the operation of the steering handle 11 during traveling. ing. Although not shown in FIG. 3, a brake pedal operated by the driver is provided on the vehicle body 2, and while the brake pedal is being depressed, the rotary shaft of the drive traveling motor for the drive wheels 7 is rotated. The drive wheel braking unit, which is a disc brake that locks and brakes the drive wheel 7, is unlocked to enable traveling, and when the brake pedal is released, the drive wheel braking unit locks the rotation shaft of the traveling motor. Braking force is applied to the drive wheels 7.

[0004]

By the way, in the case of the reach type forklift 1, as shown in FIG. 4, the drive wheels 7 are usually not arranged on the center line in the front-rear direction passing through the center of the vehicle body 2. Since they are arranged left and right with respect to the center line (here, to the left), a rotational moment acts on the vehicle body 2 due to the braking force of the drive wheels 7 and the inertial force of the vehicle body 2, and the driver's expectation There was a problem that the vehicle body 2 started to turn in the direction not to do so.

Further, in the reach type forklift 1, since the load applied to the drive wheel 7 varies greatly depending on the presence or absence of a load and the front and rear position of the mast 5, the drive wheel 7 may be changed in some cases.
There is also a problem that the load applied to the vehicle is insufficient and slip occurs during acceleration drive or braking. Further, in the reach type forklift 1, the drive wheels 7 and the caster wheels 8 are attached to the vehicle body 2 via the suspension mechanism, but the drive wheels 7 or the caster wheels 8 sink due to the movement of the load at the time of turning, and at the time of turning acceleration / deceleration. Left front wheel 6l or right front wheel 6
There was also the problem that r would rise.

Therefore, in order to stabilize the posture of the vehicle body 2 during sudden acceleration / deceleration, front wheel braking devices are provided on the left and right front wheels 6l and 6r, respectively, and the front wheel brakes are based on the speeds of the front wheels 6l and 6r. A measure for controlling the device (hereinafter, simply referred to as attitude control) is taken. In order to prevent slip during acceleration driving or braking, for example, a so-called traction is used in which the traveling motor and the driving wheel braking device are controlled so that the speed of the driving wheels 7 matches the speed of the front wheels 6l and 6r. A measure to apply the control (hereinafter referred to as anti-slip control) is taken. In order to prevent the lifting of the front wheels, for example, a lock cylinder that restricts (locks) the vertical movement of the suspension mechanism is provided, and the lock cylinder is controlled based on the speed of both front wheels 6l and 6r. Suspension control) is done. In order to implement each of these countermeasures, the speed of both front wheels 6l, 6r is detected at the same time by, for example, rotation sensors provided on both front wheels 6l, 6r.

The speeds of both front wheels 6l and 6r necessary for controlling the devices relating to the above-mentioned countermeasures are the peripheral speeds, and the rotation sensors detect both front wheels 6l and 6r.
Since the rotation speeds are 1 and 6r, conventionally, the detected rotation speeds Nl and Nr of the front wheels 6l and 6r are multiplied by the preset wheel diameters Df of the front wheels 6l and 6r, respectively.
A method of deriving the peripheral velocities Vl and Vr of V. That is, Vl = Nl × Df ... (1) Vr = Nr × Df ... (2) is calculated, and the peripheral speeds Vl and Vr of both front wheels 6l and 6r derived as a result are used to implement the above countermeasures. The devices involved were controlled respectively.

However, in the calculations of the above equations (1) and (2), the wheel diameters Df of the front wheels 6l and 6r are treated as constant, so that the front wheels 6 can be used for a long period of time.
If the tire wear of only one of the front wheels 6l and 6r is extremely advanced, or if only one of the front wheels 6l and 6r is replaced with a new tire, the accurate peripheral speed Vl of the front wheels 6l and 6r, There is a problem in that Vr cannot be obtained, and as a result, the accuracy of each control described above based on the peripheral velocities Vl and Vr of the front wheels 6l and 6r decreases. In particular, when the tire wear progresses or the balance between the front wheels 6l and 6r is lost, the safety and stability of the reach-type forklift 1 deteriorates. It had to be done with precision.

Therefore, an object of the present invention is to provide a control device capable of highly accurate posture control, anti-slip control, and automatic suspension control.

[0010]

In order to achieve the above object, the present invention comprises a pair of left and right front wheels, rear wheels and caster wheels, in which the rear wheels are rotationally driven by a traveling motor to travel and steer. In a reach type forklift control device for turning and steering the rear wheels by means of a device, left and right front wheel speed detection units for respectively detecting rotational speeds of the front wheels, and a steering angle for detecting a steering angle of the rear wheels. A detector,
Based on the rotational speeds of the front wheels detected by the front wheel speed detection units, the steering angles of the rear wheels detected by the steering angle detection unit, and the arrangement dimensions of the front wheels and the rear wheels, It is provided with a derivation unit that derives a left-right wheel diameter ratio of the front wheels by calculation, and a control unit that controls a device provided in each part of the vehicle body based on the left-right wheel diameter ratio derived by the derivation unit. I am trying.

According to this structure, the front wheel speed detecting sections detect the rotation speeds of the front wheels, and the steering angle detecting section detects the steering angle. The left / right wheel diameter ratio is derived by the deriving unit based on the steering angle and the arrangement dimensions of the front wheels and the rear wheels, and the turning radius and the turning angular velocity in consideration of tire wear of both front wheels are calculated using the left / right wheel diameter ratio. The slip value or the like of the drive wheels can be obtained.

Therefore, unlike the conventional control that does not consider tire wear of both front wheels, by introducing a left / right wheel diameter ratio, highly accurate posture control and anti-slip control considering tire wear of both front wheels. Control and automatic suspension control can be realized. Further, since the left and right wheel diameter ratios are derived by calculation instead of obtaining the wheel diameters of the left and right front wheels, it is possible to more easily realize highly accurate control.

Further, the present invention is characterized in that the deriving unit obtains a change in the left / right wheel diameter ratio by a calculation of a first-order lag system and corrects the left / right wheel diameter ratio. According to such a configuration, the change in the left / right wheel diameter ratio is calculated by the calculation of the first-order lag system and the left / right wheel diameter ratio is corrected, so that the noise included in the detected rotation speeds of both front wheels and the steering angle is detected. The influence can be suppressed, and a stable left / right wheel diameter ratio can always be obtained.

Further, according to the present invention, the derivation unit obtains a change amount of the left and right wheel diameter ratio by using a ratio of the rotational speeds of the both front wheels by the front and rear wheel speed detection units, and calculates the change of the left and right wheel diameter ratio. The feature is that correction is performed.

According to such a construction, the forklift may sometimes turn, but in terms of the entire operation, it can be approximated that the vehicle is traveling straight ahead. By calculating the change amount of the left / right wheel diameter ratio by using and correcting the left / right wheel diameter ratio, a stable left / right wheel diameter ratio can be obtained by a simple calculation.

In this case, the steering angle can be calculated based on the detected rotation speeds of both front wheels and the wheel diameters of both front wheels even if the steering angle detection unit for detecting the steering angle of the driving wheels is not provided. The steering angle obtained by this calculation can be used to derive the left-right wheel diameter ratio by the deriving unit, and the left-right wheel diameter ratio can be corrected, which is advantageous in that a simple configuration is sufficient.

Further, the present invention is characterized in that the lead-out portion automatically calculates the right and left wheel diameter ratio at least when the lead-out portion is traveling straight or traveling at a constant speed. With such a configuration, at least when the vehicle is in a straight traveling state and is not accelerating, there is no possibility that the calculation result of the left / right wheel diameter ratio is disturbed, and a stable left / right wheel diameter ratio can be obtained by automatic calculation.

Further, according to the present invention, the control section is derived by the rotational speeds of the front wheels detected by the front wheel speed detection sections, the arrangement dimensions of the front wheels and the rear wheels, and the derivation section. Based on the left / right wheel diameter ratio, the peripheral speed of the rear wheel and / or the steering angle of the rear wheel is calculated, and each of the devices is controlled according to the calculated value. According to such a configuration,
The peripheral speed and / or the steering angle of the rear wheels can be calculated more accurately.

Further, according to the present invention, each of the above-mentioned devices includes a front wheel brake for braking both front wheels, a traveling motor for driving the rear wheels, a rear wheel brake for braking the rear wheels,
Alternatively, it is characterized in that it is at least one of locking devices for restricting vertical movement of a suspension mechanism for suspending the rear wheel on a vehicle body. With such a configuration, control of at least one of the front wheel brake, the traveling motor, the rear wheel brake, and the suspension mechanism locking device can be performed with high accuracy.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment in which the present invention is applied to anti-slip control in a reach type forklift will be described with reference to FIGS. 1 and 2. However,
FIG. 1 is a block diagram and FIG. 2 is an operation explanatory diagram. The reach-type forklift according to the present embodiment has a basic configuration in common with the conventional one shown in FIGS. 3 and 4, and therefore will be described below with reference to FIGS. 3 and 4.

As shown in FIG. 1, the reach type forklift 1 according to this embodiment has drive wheels 7 (see FIGS. 3 and 4).
Drive motor 20 for driving, and a motor driver 21 composed of a chopper circuit or an inverter circuit for driving this motor 20 are provided, and the left and right front wheel speeds for detecting the rotational speeds Nl, Nr of both front wheels 6l, 6r, respectively. Left and right front wheel encoders 22 and 23 are provided as detection units, and a potentiometer 24 is provided as a steering angle detection unit that detects the steering angle θ of the drive wheels 7.

Further, as shown in FIG. 1, both front wheels 6l, respectively detected by the front wheel encoders 22, 23,
The rotation speeds Nl, Nr of 6r, the steering angle θ detected by the potentiometer 24, and the left-right wheel diameter ratio Kl represented by the substantial wheel diameters Dfl, Dfr of the front wheels 6l, 6r.
A derivation unit 26 for deriving r by calculation is provided, and the left / right wheel diameter ratio Klr by the derivation unit 26 is used to control the terminal voltage to be supplied to the traveling motor 20 in order to prevent the drive wheels 7 from slipping. A control unit 27 that controls 21 is provided.

The derivation unit 26 is provided for both front wheel encoders 2.
The left and right wheel diameter ratio Klr is calculated based on the rotational speeds Nl and Nr of the front wheels 6l and 6r detected by 2 and 23, the steering angle θ by the potentiometer 24, and the arrangement dimensions of the front wheels 6l and 6r and the drive wheel 7. (= Dfr / D
fl) is derived.

At this time, as shown in FIG. 2, the steering angle of the drive wheels 7 in the state where the instantaneous turning center of the vehicle body 2 is at the point P is θ, and the front wheels 6l, 6r of the front wheels 6l, 6r are controlled by the front wheel encoders 22, 23. If the rotation speeds are Nl and Nr respectively,
The steering angle of the drive wheels 7 can be obtained by calculation, and the steering angle θ * calculated at that time is θ * = tan ⁻¹ {B × (Nl × Dfl-Nr × Dfr) / (Al × Dfr × Nr + Ar × Dfl × Nl)}… (3) Here, as shown in FIG. 2, Al is the horizontal dimension between the center of the left front wheel 6l and the center of the drive wheel 7, and Ar
Is the lateral dimension of the center of the right front wheel 6r and the center of the drive wheel 7, and B is the longitudinal dimension of the center of the front wheels 6l, 6r and the center of the drive wheel 7.

Then, for this equation (3), both front wheels 6
Introducing the left-right wheel diameter ratio Klr (= Dfr / Dfl) of 1 and 6r, the equation (3) becomes θ * = tan ⁻¹ {B × (Nl-Nr × Klr) / (Al × Nr × Klr + Ar × Nl)} is rewritten as (4). Therefore, by using the actual steering angle θ detected by the potentiometer 24 as θ * in the equation (4), the left / right wheel diameter ratio Klr can be calculated as Klr = (Nl / Nr-tan θ × Ar × Nl / Nr / B) / (1 + tan θ × Al / B) ... (5)

Further, the deriving unit 26 automatically calculates the left / right wheel diameter ratio Klr when at least one of the following conditions is satisfied in order to eliminate the error factor of the left / right wheel diameter ratio Klr. That is, both front wheels 6l, 6 by both front wheel encoders 22, 23
Steering by the potentiometer 24 when the rotational speeds Nl and Nr of r are stable, that is, when not accelerating, when the magnitude of Nr becomes a certain value or more to suppress the calculation error of Nl / Nr. In order to suppress the detection error of the angle θ, the magnitude of θ is equal to or less than a certain value, that is, when the vehicle is traveling straight ahead. By doing this, the error in the measured values of Nl, Nr, and θ is minimized, and the left / right wheel diameter ratio Klr is calculated.
The error of can be suppressed.

Further, the deriving unit 26 obtains a change amount Δk of the left / right wheel diameter ratio Klr by a calculation of a first-order lag system and corrects the left / right wheel diameter ratio Klr. That is, the change amount Δk of the left / right wheel diameter ratio Klr is Δk = k × {(Nl / Nr-tanθ × Ar × Nl / Nr / B) / (1 + tanθ × Al / B) -Klr} (6) In order to suppress noise, the derivation unit 26 corrects the left / right wheel diameter ratio Klr using the variation Δk according to the equation (6). The right / left wheel diameter ratio Klr thus corrected may be stored in a backup memory or the like as an updated value and used as an initial value when the key switch for powering on next time is turned on.

Here, k is a positive constant, and the above (6)
Klr in the curly brackets in the expression is the value of the left / right wheel diameter ratio obtained by the previous calculation, and in the end, the value in the curly brackets is the value of the left / right wheel diameter ratio obtained by the current calculation and the previous calculation. The difference between the obtained right and left wheel diameter ratios is represented, and the change Δk is the difference multiplied by k.

By the way, considering the case of straight traveling, it is considered that ∫ {tan θ × Nl / Nr / (1 + tan θ × Al / B)} dt = 0 (7), and the above (6) Since the equation can be rewritten as Δk = k × (Nl / Nr-Klr) (8), the rotational speeds Nl, Nr of the detected front wheels 6l, 6r can be calculated from the above equation (5).
And based on the wheel diameters Dfl and Dfr of the front wheels 6l and 6r,
The steering angle θ * is calculated, and the steering angle θ
By using *, even if the potentiometer 24 for detecting the steering angle θ of the drive wheels 7 is not provided,
The left / right wheel diameter ratio Klr can be corrected.

If the constant k in the equations (6) and (8) is increased, the sensitivity of automatic adjustment is increased and the adjustment can be performed quickly. On the other hand, when k is small, the adjustment speed is slow, but there is an advantage that stability and noise resistance in the adjustment process are improved. Since tire wear progresses over a long period of time, it is desirable to set a small value of k to the extent that the tire wear rate is met in order to obtain a stable adjustment value.

In this way, both front wheel encoders 22, 2
The rotation speeds Nl, Nr of both front wheels 6l, 6r are respectively detected by 3 and the steering angle θ is detected by the potentiometer 24, and the detected rotation speeds Nl, Nr of both front wheels 6l, 6r and the drive wheels 7 are detected. Based on the steering angle θ and the arrangement dimensions of both front wheels 6l, 6r and drive wheel 7, the derivation unit 2
A left / right wheel diameter ratio Klr (= Dfr / Dfl) is derived by 6, and both front wheels 6 are used by using this left / right wheel diameter ratio Klr.
A turning radius, a turning angular velocity, a slip value of a driving wheel, and the like are calculated in consideration of tire wear of 1 and 6r.

That is, the control unit 27 receives the calculation result of the left / right wheel diameter ratio Klr from the derivation unit 26, and at the same time, the derivation unit 26.
The rotational speeds Nl and Nr of the front wheels 6l and 6r are received via the peripheral speed Vd1 of the driving wheel 7 by: Vd1 = {B ² × (Nl-Nr × Klr) ² / (Al × Nr × Klr + Ar × Nl) ² } ^1/2 ... Derived by the operation of (9). In addition, the steering angle θ1 of the drive wheels 7
Is derived by the calculation of θ1 = tan ⁻¹ {B × (Nl−Nr × Klr) / (Al × Nr × Klr + Ar × Nl)} (10). In addition, if necessary, the driving wheels 7 may be used by using the calculation results of the above equations (9) and (10).
The turning radius L1 and the turning angular velocity ω1 of the vehicle body 2 can be derived by the calculation of L1 = B / sin θ1 (11) ω1 = Vd1 / L1 = Vd1 × sin θ1 / B (12).

On the other hand, as shown in FIG. 1, the drive wheel 7 is provided with an encoder 30 for detecting its rotational speed Nd, and the control unit 27 controls the rotational speed Nd of the drive wheel 7 detected by the encoder 30. Based on the actual peripheral speed Vd of the drive wheels 7, anti-slip control is performed. That is, the wheel diameter of the drive wheel 7 is set as a predetermined value Dd, and the actual peripheral speed Vd of the drive wheel 7 is derived by calculating Vd = Nd × Dd (13). The peripheral speed Vd of the above and (9)
The difference from the peripheral speed Vd1 derived by the calculation of the formula represents the idling (that is, slip) of the drive wheel 7 that is occurring, and the control unit 27 gives a command signal to the motor driver 21 so as to eliminate this difference. The motor driver 21 controls the traveling motor 20 according to the command signal to suppress the slip of the drive wheels 7.

More specifically, when Vd> Vd1 at the time of power running, the control unit 27 determines that the drive wheels 7 have been excessively rotationally driven, and suppresses the output of the traveling motor 20 that drives the drive wheels 7. Take control. If Vd <Vd1 during braking, it is determined that the braking force on the drive wheels 7 is excessive, and control is performed to reduce the braking force on the drive wheels 7. It is to be noted that what is controlled in order to suppress the slip of the drive wheels 7 is not limited to the traveling motor 20 but is a drive wheel brake for braking the drive wheels 7 and a front wheel brake for braking both front wheels 6l, 6r. May be. That is, when Vd <Vd1 during braking, it is determined that the driving wheels 7 are excessively braked, and the output (braking force) of the driving wheel brakes that brakes the driving wheels 7
May be controlled, or it may be determined that the front wheels 6l, 6r are not sufficiently braked, and the control for increasing the front wheel brake output (braking force) may be performed. The drive wheel brake that applies the brake to the drive wheel 7 corresponds to the rear wheel brake in the present invention.

Here, as the drive wheel brake, an electromagnetic brake or the like separate from the traveling motor for braking the traveling motor 20 can be used, or the traveling motor 20 can be rotated by reversing the direction of rotation. It may be an electric regenerative brake that brakes the vehicle. Further, in order to suppress the slip of the driving wheels 7, the front wheel brake and the traveling motor 2
The control of the drive wheel brakes as 0 and the rear wheel brakes may be performed in combination of two or more.

Therefore, according to the above-described embodiment, unlike the conventional anti-slip control that does not consider tire wear of both front wheels 6l and 6r, the above-mentioned (5) is adopted.
By introducing the left / right wheel diameter ratio Klr according to the formula, it is possible to always obtain a highly accurate left / right wheel diameter ratio Klr in consideration of tire wear of both front wheels 6l, 6r, and realize highly accurate anti-slip control. be able to. In addition, both front wheels 6
Since the wheel diameters Dfl and Dfr of 1 and 6r are not calculated respectively, but the left and right wheel diameter ratio Klr is derived by calculation, it is possible to deal with the case where either of the front wheels 6l and 6r wears the tire. Even if the front wheels 6l and 6r are worn hard, it is possible to deal with them. further,
When obtaining the wheel diameters Dfl and Dfr of both front wheels 6l and 6r respectively, it is necessary to store the wheel diameters Dfl and Dfr respectively, but by introducing the left / right wheel diameter ratio Klr, only the left / right wheel diameter ratio Klr Is stored, and the stored data of the left / right wheel diameter ratio Klr may be read also when the anti-slip control is performed. That is, according to the above-described embodiment, highly accurate control can be realized more easily.

When one of the front wheels 6l and 6r is worn out so severely that it needs to be replaced, both the left and right wheels must be replaced with new ones in the prior art. Since the diameter ratio Klr is derived and the anti-slip control can be performed accurately based on this, even when one of the front wheels 6l, 6r is heavily worn, it is not necessary to replace both tires, and high-precision anti-slip control is possible. From the viewpoint of safety, not for realizing the slip control, it is sufficient to replace the one with severe wear.

Further, the derivation unit 26 uses the above (6).
In order to correct the left / right wheel diameter ratio Klr by obtaining the change amount Δk of the left / right wheel diameter ratio Klr by the calculation of the first-order lag system of the equation, the detected rotation speeds Nl, Nr of both front wheels 6l, 6r and the steering angle θ
It is possible to suppress the influence of the noise contained in, to always obtain a stable left / right wheel diameter ratio Klr, and to further improve the anti-slip control.

In the above embodiment, the case where the automatic calculation of the left and right wheel diameter ratio Klr is performed when all of the three conditions (1) to (3) are satisfied is described, but not all of these conditions are necessarily required. . For example, even if most of the passage on which the forklift travels is curved or bent, according to the present invention, the left-right wheel diameter ratio Klr can be automatically calculated even during turning, so anti-slip control, etc. The accuracy of can be improved. Also,
According to the present invention, the left and right wheels can be used even if the traveling operation is limited because the working space is limited and it is difficult to travel a certain distance at a constant speed or the switching between acceleration and deceleration is frequently performed. The diameter ratio Klr can be automatically calculated, and the accuracy of anti-slip control and the like can be improved. That is, the left / right wheel diameter ratio can be derived during straight traveling and turning, and the left / right wheel diameter ratio can be derived during acceleration / deceleration traveling or constant speed traveling. It is possible to realize highly accurate control.

Further, in the above embodiment, the case where the present invention is applied to the anti-slip control has been described.
Needless to say, the present invention can be applied to attitude control and automatic suspension control, and in this case as well, highly accurate control can be realized as in the above-described embodiment.

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

[0042]

As described above, according to the first aspect of the invention, both front wheel speed detecting portions detect the rotational speeds of both front wheels, and the steering angle detecting portion detects the steering angle. Based on the detected rotation speeds of both front wheels, the steering angle, and the wheel diameters of both front wheels, the deriving unit derives the left-right wheel diameter ratio, and considers tire wear of both front wheels. Since it is possible to obtain the slip value etc. of both front wheels, unlike the conventional attitude control, anti-slip control and automatic suspension control that do not consider tire wear of both front wheels, by introducing the left and right wheel diameter ratio, High-precision posture control, anti-slip control, and automatic suspension control that take into account the wear of each tire are possible. Further, since the left and right wheel diameter ratios are derived by calculation instead of obtaining the wheel diameters of the left and right front wheels, it is possible to more easily realize highly accurate control.

According to the second aspect of the present invention, the rotational speeds of both front wheels detected by calculating the change in the left / right wheel diameter ratio by the calculation of the first-order lag system and correcting the left / right wheel diameter ratio. It is possible to suppress the influence of noise contained in the steering angle and always obtain a stable left / right wheel diameter ratio.

According to the invention described in claim 3, the movement of the forklift may sometimes make a turn, but when viewed from the whole movement, it is considerably longer in a straight traveling state. Since it can be approximated as if the vehicle is traveling straight ahead, it is easy to calculate by calculating the change in the left / right wheel diameter ratio using the rotation speed ratio of both front wheels and correcting the left / right wheel diameter ratio. This makes it possible to obtain a stable left / right wheel diameter ratio.

Further, even if the steering angle detecting section for detecting the steering angle of the driving wheels is not provided, the steering angle can be calculated based on the detected rotation speeds of both front wheels and the wheel diameters of both front wheels. Using the steering angle obtained by this calculation, the deriving unit can derive the left / right wheel diameter ratio, and the left / right wheel diameter ratio can be corrected, which is advantageous in that a simple configuration is sufficient.

Further, according to the invention described in claim 4, there is no possibility that the calculation result of the left and right wheel diameter ratio is disturbed at least when the vehicle is in a straight traveling state and is not being accelerated, and stable left and right wheels are obtained by automatic calculation. It is possible to obtain the diameter ratio.

According to the fifth aspect of the invention, the peripheral speed and / or the steering angle of the rear wheels can be calculated more accurately.

According to the invention of claim 6, it is possible to control at least one of the front wheel brake, the traveling motor, the rear wheel brake, and the suspension mechanism locking device with high accuracy. become.

[Brief description of drawings]

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

FIG. 2 is an operation explanatory diagram of the embodiment of the present invention.

FIG. 3 is a perspective view of a reach type forklift truck as a background of the present invention.

FIG. 4 is a plan view schematically showing a reach type forklift truck which is a background of the present invention.

[Explanation of symbols]

1 Reach type forklift 6l, 6r Left, right front wheel 7 Drive wheel 20 Travel motor 22, 23 Left, right front wheel encoder (left, right front wheel speed detection unit) 24 Potentiometer (steering angle detection unit) 26 Derivation unit 27 Control unit

Claims (6)

[Claims] 1. A reach-type forklift control comprising a pair of left and right front wheels, rear wheels and caster wheels, wherein a traveling motor drives the rear wheels to rotate to drive, and a steering device drives the rear wheels to turn to steer. In the device, left and right front wheel speed detection units that detect the rotation speeds of the front wheels, a steering angle detection unit that detects the steering angle of the rear wheels, and the front and rear wheel speed detection units that detect the front wheel speeds of the front and rear wheels, respectively. A derivation unit for deriving a left / right wheel diameter ratio of both front wheels by calculation based on the rotational speed of the front wheels, the steering angle of the rear wheels detected by the steering angle detection unit, and the arrangement dimensions of the front wheels and the rear wheels. Based on the left / right wheel diameter ratio derived by the derivation unit,
A reach-type forklift control device comprising: a control unit that controls devices provided in each part of the vehicle body. 2. The reach type forklift according to claim 1, wherein the derivation unit obtains a change in the left / right wheel diameter ratio by a calculation of a first-order lag system and corrects the left / right wheel diameter ratio. Control device. 3. The derivation unit obtains a change amount of the left / right wheel diameter ratio by using a ratio of the rotational speeds of the both front wheels by the front wheel speed detection units, and corrects the left / right wheel diameter ratio. The reach-type forklift control device according to claim 1. 4. The reach type according to claim 1, wherein the lead-out section automatically calculates the left-right wheel diameter ratio at least when the vehicle is in a straight traveling state or is traveling at a constant speed. Forklift control device. 5. The control unit controls the rotation speeds of the front wheels detected by the front wheel speed detection units, the arrangement dimensions of the front wheels and the rear wheels, and the left and right wheels derived by the derivation unit. 5. The peripheral speed of the rear wheel and / or the steering angle of the rear wheel is calculated based on the diameter ratio, and each of the devices is controlled according to the calculated value. A reach type forklift control device according to any one of the claims. 6. The front wheel brake for braking each of the front wheels, the traveling motor for driving the rear wheel, wherein:
At least one of a rear wheel brake for braking the rear wheel and a lock device for restricting vertical movement of a suspension mechanism for suspending the rear wheel on a vehicle body. A reach type forklift control device according to any one of the claims.