JP2003063796A - Control device for reach type forklift - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device capable of performing accurate anti-slip control considering the wear of a tire. SOLUTION: Revolution speeds Nl, Nr of both front wheels are detected with both front wheel encoders 22, 23, the target circumferential speed of a driving wheel is computed with a derivation part 26 based on the revolution speeds Nl, Nr of the both front wheels, nominal diameters of the front wheels, and a steering angle θ with a potentiometer 25, a slip speed computing value s* of the driving wheel is computed based on the revolution speed Nd measured with an encoder 24 for the driving wheel, a circumferential speed detecting value found from the nominal diameter of the driving wheel and a wheel diameter variation coefficient, and the difference between the circumferential speed detecting value and a target circumferential speed Vdt, and the wheel diameter variation coefficient is adjusted, terminal voltage based on the slip speed computing value s* is supplied to a traveling motor 20 with a control part 27, and slip of the driving wheel is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reach type forklift control device having a pair of left and right front wheels, a drive wheel, and a caster wheel, and driving the drive wheels by a traveling motor. Regarding

[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 one drive wheel 7 is attached to the lower rear portion of the vehicle body 2 to support the vehicle body 2 and to advance the vehicle body 2. Two driven caster wheels 8 are attached.

Further, as shown in FIG. 4, 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. Although not shown in FIG. 4, 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 motor for driving the drive wheels 7 is rotated. The drive wheel braking unit, which consists of a disc brake that locks and brakes the drive wheel 7, is unlocked so that the vehicle can run.
When the brake pedal is released, the drive wheel braking unit locks the rotary shaft of the traveling motor so that the drive wheel 7 receives a braking force.

[0004]

By the way, in the case of the reach type forklift 1, normally, as shown in FIG. 5, the drive wheels 7 are not arranged on the center line in the front-rear direction passing through the center of the vehicle body 2. Since the drive wheels 7 are arranged so as to be displaced to the left and right (here, to the left) with respect to the center line, slippage of the drive wheels 7 is likely to occur, and the braking force of the drive wheels 7 and the inertial force of the vehicle body 2 cause the vehicle body 2 to move. There is a problem in that the vehicle body 2 starts to turn in a direction that is not expected by the driver due to the rotational moment acting.

In order to prevent such a slip of the drive wheel 7, if the slip of the drive wheel 7 occurs, the rotational speed of the drive wheel 7 may be controlled so as to match the rotational speeds of the front wheels 6l and 6r. As a similar control, there is a traction control system in a passenger vehicle, but it is possible to apply this method to the battery-type reach type forklift 1 to perform anti-slip control. At this time, it is necessary to calculate a target rotation speed at which the drive wheels 7 do not slip and control the traveling motor so that the target rotation speed is reached.

However, the drive wheels 7 in this case
The target circumferential speed of can be calculated based on, for example, the rotational speeds of the front wheels 6l and 6r detected by the encoder, the steering angle detected by the potentiometer, and geometrical dimensions such as the nominal diameters of the front wheels 6l and 6r. , Front wheels 6l, 6r
Since the speed detection is not the circumferential speed but the rotation speed on the wheel axle, the target circumferential speed of the drive wheel 7 cannot be said to be accurate in consideration of wear of the front wheels 6l and 6r.

On the other hand, the actual rotation speed of the drive wheel 7 is also detected by the encoder, but this is not the circumferential speed of the wheel but the rotation speed of the wheel axle. Unlike the wheel circumferential speed in
Thus, the slip speed derived from the difference between the detected rotational speed of the drive wheel 7 and the target wheel circumferential speed that does not consider tire wear is also different from the value when tire wear is taken into consideration.

As a result, high-precision anti-slip control cannot be realized, and as tire wear progresses, it becomes impossible to suppress slip, and tire wear is rather promoted.

Therefore, an object of the present invention is to provide a control device capable of highly accurate anti-slip control in consideration of tire wear.

[0010]

In order to achieve the above-mentioned object, the present invention includes a pair of left and right front wheels, a drive wheel, and a caster wheel, and a reach type forklift control device for driving the drive wheel by a traveling motor. In, the potentiometer for detecting the steering angle of the drive wheels, the left, right front wheel speed detection unit for detecting the rotation speed of each of the front wheels,
A drive wheel speed detection unit for detecting the rotational speed of the drive wheel,
The rotational speeds of the front wheels detected by the front wheel speed detection units, the steering angle by the potentiometer,
And the nominal diameters of the front wheels and the wheel diameter change coefficient, and calculates a target circumferential speed of the driving wheel, and a circumferential speed detection value of the driving wheel obtained from a detection value by the driving wheel speed detection unit. A calculation unit that calculates a slip speed calculation value of the driving wheels based on a difference from the target circumferential speed, a ratio between the substantial diameters of the front wheels and the driving wheels, and a nominal diameter of the driving wheels. And an adjustment unit for adjusting the wheel diameter change coefficient, which is expressed by a ratio of the nominal diameters of the both front wheels and is derived by proportional-plus-integral control based on the slip speed calculation value. There is.

According to this structure, the front and rear wheel speed detecting portions detect the respective front and rear wheel rotational speeds, and the potentiometer detects the steering angle. The detected front and rear wheel rotational speeds and steering angle, Based on the nominal diameters of both front wheels and the wheel diameter change coefficient, the calculation unit calculates the target circumferential speed of the drive wheels, and the circumferential speed obtained from the rotation speed of the drive wheels detected by the drive wheel speed detection unit. Based on the difference between the detected value and the target circumferential speed, the calculated slip speed of the drive wheels is calculated, and the adjustment unit adjusts the wheel diameter change coefficient to perform anti-slip control using the calculated slip speed considering tire wear. Is done.

Therefore, unlike the conventional anti-slip control that does not consider tire wear, it is possible to implement highly accurate anti-slip control that considers tire wear by introducing a wheel diameter variation coefficient.

Further, according to the present invention, the adjusting unit derives the wheel diameter change coefficient by a calculation based on a term proportional to the integral of the slip speed calculated value and a term proportional to the slip speed calculated value. It is characterized by that. According to such a configuration, the wheel diameter change coefficient can be derived using the proportional-plus-integral control law, so that the wheel diameter change coefficient that is less susceptible to noise and converges to a constant value can be obtained.

Further, according to the present invention, the adjusting section includes a first variable coefficient for the integral term of the slip speed calculated value in the calculation of the wheel diameter change coefficient, and a second variable coefficient for the proportional term of the slip speed calculated value. Is variable according to whether the slip speed calculation value is positive or negative, and the wheel diameter change coefficient is adjusted by proportional-plus-integral control.

With such a configuration, the wheel diameter change coefficient is adjusted to be large or small in accordance with whether the slip speed calculated value is positive or negative. Therefore, especially when the slip speed calculated value is negative, the wheel diameter change is small. By adjusting the coefficient to be small, the stability of the calculated slip speed value can be improved.

Further, the present invention is characterized by comprising a control section for controlling a terminal voltage to be supplied to the traveling motor based on the calculated slip speed value. According to such a configuration, the control unit supplies the terminal voltage based on the calculated slip speed value to the traveling motor, so that the slip of the driving wheels can be reliably suppressed by the output control of the traveling motor.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described with reference to FIGS. However, FIG. 1 is a block diagram, FIG. 2 is an operation explanatory diagram, and FIG. 3 is an operation explanatory flowchart. Since the basic structure of the reach type forklift according to the present embodiment is the same as that shown in FIGS. 4 and 5, the description will be given below with reference to FIGS. 4 and 5.

As shown in FIG. 1, the reach type forklift 1 according to this embodiment has drive wheels 7 (see FIGS. 4 and 5).
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 as detection units are provided near the wheel axle, and a drive wheel encoder 24 as a drive wheel speed detection unit that detects the rotation speed Nd of the drive wheels 7.
Is provided near the wheel axle, and a potentiometer 25 that detects the steering angle θ of the drive wheels 7 is provided.

Further, as shown in FIG. 1, a target circumferential speed Vdt and a slip speed calculated value s * for preventing the drive wheels 7 from slipping are calculated, and a wheel diameter change coefficient Kfd based on the slip speed calculated value s * is calculated. Adjust the slip speed calculation value s
A control unit 27 for controlling the motor driver 21 is provided to control the terminal voltage to be supplied to the traveling motor 20 based on *.

This derivation unit 26 is provided for both front wheel encoders 2.
Rotational speeds Nl, Nr of both front wheels 6l, 6r detected by 2 and 23, respectively, nominal diameters Df0 of both front wheels 6l, 6r
And the target circumferential speed Vd of the drive wheels 7 based on the steering angle θ by the potentiometer 25 and the wheel diameter change coefficient Kfd.
t is calculated, and the circumferential speed detection value Vd obtained from the rotational speed Nd of the drive wheel 7 detected by the drive wheel encoder 24 and the nominal diameter Dd0 of the drive wheel 7, and the target circumferential speed Vdt obtained by the calculation The slip speed calculation value s * of the drive wheel 7 is calculated based on the difference between The arithmetic processing by the derivation unit 26 as described above corresponds to the arithmetic unit.

Further, the lead-out portion 26 has a ratio (= Df / D) between the substantial diameter Df of the front wheels 6l and 6r and the substantial diameter Dd of the driving wheel 7.
d) and the nominal diameter Dd0 of the drive wheel 7 and both front wheels 6l, 6
A wheel diameter change coefficient Kfd represented by multiplication of the ratio of r to the nominal diameter Df0 (= Dd0 / Df0), and wheel diameter change derived by proportional-plus-integral control (PI control) based on the calculated slip speed value s *. The coefficient Kfd is automatically adjusted to obtain the slip speed calculation value s * considering tire wear. The adjustment process by the deriving unit 26 corresponds to the adjusting unit.

As will be described later in detail, the wheel diameter variation coefficient Kfd is derived by calculation based on a term proportional to the integral of the slip speed calculated value s * and a term proportional to the slip speed calculated value s *. , The first variable coefficient K1 for the integral term of the slip speed calculation value s * in the calculation of the wheel diameter change coefficient Kfd, and the second variable coefficient K2 for the proportional term of the slip speed calculation value are the slip speed calculation value s *. Of the wheel diameter change coefficient Kf
d is automatically adjusted by proportional-plus-integral control.

By the way, as shown in FIG. 2, the steering angle of the drive wheel 7 when the instantaneous turning center of the vehicle body 2 is at the point P is θ, and the rotation of both front wheels 6l, 6r by the front wheel encoders 22, 23 is performed. Speed is Nl, Nr, both front wheels 6
When the circumferential velocities of 1 and 6r are respectively Vl and Vr, the angular velocities ω of the vehicle body 2 at that time are respectively ω = Vl / (B / tan θ + Al) = πDfNl / (B / tan θ + Al) ... (1 ) ω = Vr / (B / tan θ-Ar) = πDfNr / (B / tan θ-Ar) (2) Here, to calculate the angular velocity, (1)
Either equation or equation (2) may be used, but in order to reduce the calculation error, the above equation (2) is an equation for calculating the angular velocity ω when −180 ° + θ0 ≦ θ <0. The equation (1) is a calculation formula of the angular velocity ω when 0 ≦ θ ≦ θ0. Depending on the size of the steering angle θ, Equation (1) or
Equation (2) may be selected to calculate ω. In addition, θ0 is the steering angle of the drive wheel 7 when the instant turning center is at the center position of both front wheels 6l, 6r, Al, Ar, B are the respective dimensions as shown in FIG. 2, and Df is both front wheels 6l. , 6r substantial diameter.

From these equations (1) and (2), the target circumferential velocity Vdt 'for preventing the drive wheels 7 from slipping.
Can be expressed as Vdt ′ = ω · B / sin θ = Df · f (Nl, Nr, θ) (3). Where f (Nl, Nr, θ)
Means that it is a function of Nl, Nr, θ, and both front wheels 6
It can be calculated independently of the substantial diameter Df of 1,6r.

Further, in the drive wheel 7, the actual circumferential speed detection value Nd of the drive wheel 7 by the drive wheel encoder 24,
The actual diameter Dd of the drive wheel 7 and the target circumferential velocity V of the above equation (3)
From dt ', the slip speed s is s = Dd · | π · Nd | -Df · | f (Nl, Nr, θ) | (during acceleration) (4) s = Df · | f (Nl, Nr, θ) | -Dd · | π · Nd | (during deceleration) ... (5). However, the slip speed s when the drive wheel 7 slips
Is positive.

By the way, the front wheels 6l, 6r and the drive wheel 7
Since the actual diameters Df and Dd of f vary depending on the degree of wear, it is necessary to always know the values of Df and Dd. Therefore, the actual diameters Df, D of the front wheels 6l, 6r and the drive wheels 7 are
Using d and these nominal diameters Df0 and Dd0, for example, rewriting the above equation (4), s = (Dd / Dd0) ・ (Dd0 ・ | π ・ Nd |-(Dd0 ・ Df / Dd / Df0)・ Df0 ・ | f (Nl, Nr, θ) |} (6)

Here, the ratio of the substantial diameters Df and Dd to the nominal diameter D
If the wheel diameter variation coefficient Kfd expressed as Kfd = Dd0.Df / Dd / Df0 (7) is introduced into the equation (6) by the ratio of d0 and Df0, this equation (6) becomes s = (Dd / Dd0) ・ {Dd0 ・ ｜ π ・ Nd ｜ -Kfd ・ Df0 ・ ｜ f (Nl, Nr, θ) ｜} = (Dd / Dd0) ・ (｜ Vd ｜-｜ Vdt ｜)… (8) You can Here, Vd is a circumferential speed detection value of the drive wheel 7, which is expressed as Vd = Dd0.pi.Nd ... (9), and Vdt is a target circumferential speed of the drive wheel 7, Vdt = Kfd.Df0. It is expressed as f (Nl, Nr, θ) ... (10). By automatically adjusting the wheel diameter variation coefficient Kfd of the expression (7) in the expression (8), it is possible to obtain the slip speed calculation value s * in consideration of tire wear. The automatic adjustment of the wheel diameter variation coefficient Kfd is performed as follows.

That is, the wheel diameter change coefficient Kfd is expressed as ΔKfd = K1 · s * + K2 · Δs * (11), and the first term proportional to the integral of the slip speed calculation value s * and the slip speed The wheel diameter change coefficient Kfd is derived by addition calculation with the second term proportional to the calculation value s *. Here, the slip speed calculation value s * used for automatic adjustment of the wheel diameter change coefficient Kfd is s * = Vd-Vdt ... (12), which is a proportional value obtained by multiplying the slip speed s by Dd0 / Dd. .

Then, the first variable coefficient K1 for the first term, which is the integral of the slip speed calculation value s *, and the second variable coefficient K2 for the second term, which is the proportional of the slip speed calculation value s *, are The wheel speed change coefficient Kfd is automatically adjusted by switching to a small value or a large value set in advance depending on whether the calculated slip speed value s * is positive or negative. It is desirable to derive and set these large and small values in advance by simulation or the like.

At this time, the procedure for automatically adjusting the wheel diameter variation coefficient Kfd during power running (or during acceleration) will be described with reference to FIG.
3 will be described with reference to the flowchart of FIG. 3, it is determined whether or not the vehicle is powering (S1). If the determination result is NO, the determination is repeated until the determination result is YES, If the determination result is YES, the drive wheels 7
It is determined whether the vehicle body 2 is traveling at a constant speed and at a constant speed or higher depending on whether the difference between the detected circumferential speed Vd of V.sub.d and the target circumferential speed Vdt according to the above equation (10) is within the allowable range. (S2), and if this determination result is NO, this determination is repeated until the determination result becomes YES.

Then, the determination result of step S2 is YES.
Then, the slip speed calculation value s is calculated by the above equation (12).
* Is calculated (S3), and both variable coefficients K in the above equation (11) are calculated depending on whether the slip speed calculation value s * is positive or negative.
1 and K2 are determined (S4). At this time, as described above, when the calculated slip speed value s * is positive, a small value is selected as both variable coefficients K1 and K2, and when the calculated slip speed value s * is negative, both variable coefficients K1 and K2 are large. The value is selected.

Subsequently, as shown in FIG. 3, step S4
The wheel diameter variation coefficient Kfd is calculated by the above equation (11) using both variable coefficients K1 and K2 selected in (S).
5) Then, it is determined whether the calculated wheel diameter change coefficient Kfd is larger than a predetermined upper limit value Kfdmax (S6). If the result of this determination is YES, the wheel diameter change coefficient Kfd is the upper limit value Kfdmax. Is set (S7), and then the process returns to step S1.

On the other hand, if the decision result in the step S6 is NO, the wheel diameter variation coefficient K calculated in the step S5.
It is determined whether fd is smaller than a predetermined lower limit value Kfdmin (S8), and the determination result is YES.
If so, the wheel diameter variation coefficient Kfd is set to the lower limit value Kfdmin (S9), and then the process returns to step S1 described above,
If the determination result is NO, the process directly returns to step S1.

In this way, both front wheel encoders 22, 2
The rotation speeds Nl and Nr of both front wheels 6l and 6r are detected by 3 and the derivation unit 26 detects both front wheels 6l and 6r.
Rotational speeds Nl, Nr, nominal diameters Df of both front wheels 6l, 6r
0, the steering angle θ by the potentiometer 25, and the wheel diameter change coefficient Kfd, based on the target circumferential speed Vdt of the drive wheels 7.
Is calculated, and the circumferential speed detection value Vd obtained from the rotational speed Nd of the drive wheel 7 and the nominal diameter Dd0 of the drive wheel 7 by the drive wheel encoder 24 and the target circumferential speed V
Based on the difference with dt, the calculated slip speed s of the drive wheels 7
* Is calculated, the wheel diameter change coefficient Kfd is automatically adjusted,
The control unit 27 supplies the terminal voltage based on the slip speed calculation value s * in consideration of tire wear to the traveling motor 20 to control the output of the traveling motor 20, thereby preventing the drive wheel 7 from slipping. .

Therefore, according to the above-described embodiment, unlike the conventional anti-slip control that does not consider tire wear, by introducing the wheel diameter variation coefficient Kfd, highly accurate anti-slip that considers tire wear can be achieved. Control can be realized.

Further, in order to adjust the wheel diameter change coefficient Kfd by changing both the variable coefficients K1 and K2 to small and large in accordance with the positive or negative of the slip speed calculated value s *, the slip speed calculated value s * is particularly adjusted. By greatly adjusting the wheel diameter change coefficient Kfd when is negative, it is possible to improve the stability of the slip speed calculation value s *.

In the above-described embodiment, the case where the front wheel speed detecting section and the driving wheel circumferential speed detecting section are respectively constituted by the encoders 22, 23, 24 has been described. However, for example, the encoder 22 is not used. ，
Alternatively, the rotation speed Nd of the drive wheels 7 may be obtained by only 23.

Further, in the above-described embodiment, the procedure of automatic adjustment of the wheel diameter variation coefficient Kfd at the time of power running has been described with the flowchart of FIG. 3, but the automatic adjustment of the wheel diameter variation coefficient Kfd at the time of braking (or deceleration) is performed. 3 is almost the same as the flow shown in the flowchart in FIG. 3, but the slip speed calculation value s * in step S3 in FIG. 3 is calculated by an equation obtained by modifying the above equation (5). Only the difference.

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.

[0040]

As described above, according to the first aspect of the present invention, both front wheel speed detecting portions detect the rotational speeds of both front wheels, and the potentiometer detects the steering angle. Based on the rotational speeds of both front wheels, the steering angle, the nominal diameters of both front wheels, and the wheel diameter change coefficient, the calculation unit calculates the target circumferential speed of the drive wheels and the drive detected by the drive wheel speed detection unit. The slip speed calculation value of the driving wheel is calculated based on the difference between the detected circumferential speed value obtained from the rotational speed of the wheel and the target circumferential speed, and the wheel diameter change coefficient is adjusted by the adjustment unit to consider tire wear. Since the anti-slip control using the slip speed calculated value is performed, unlike the conventional anti-slip control that does not consider tire wear, the wheel diameter variation coefficient is introduced to improve the accuracy considering tire wear. There it becomes possible to realize the anti-slip control, it is possible to provide a control device capable of high anti-slip control precision in consideration of tire wear.

According to the second aspect of the invention, the wheel diameter variation coefficient can be derived using the proportional-plus-integral control law.
It is possible to obtain a wheel diameter variation coefficient that converges to a constant value that is less susceptible to noise.

According to the third aspect of the invention, the wheel diameter variation coefficient is adjusted to be large or small in accordance with whether the slip speed calculated value is positive or negative. By adjusting the wheel diameter variation coefficient to be small, it is possible to improve the stability of the calculated slip speed value.

According to the fourth aspect of the present invention, since the control unit supplies the terminal voltage based on the calculated slip speed value to the traveling motor, the output of the traveling motor is controlled to ensure the slip of the driving wheels. It becomes possible to suppress.

[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 flowchart for explaining the operation of the embodiment of the present invention.

FIG. 4 is a perspective view of a reach type forklift truck as a background of the present invention.

FIG. 5 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 Traveling motor 22, 23 Left, right front wheel encoder (left, right front wheel speed detection unit) 24 Drive wheel encoder (drive wheel speed detection unit) 25 Potentiometer 26 Derivation unit 27 Control unit

Claims (4)

[Claims] 1. A controller for a reach type forklift having a pair of left and right front wheels, a drive wheel, and a caster wheel, wherein the drive wheels are driven by a traveling motor. A potentiometer for detecting a steering angle of the drive wheels; Left, right front wheel speed detection unit for detecting the rotation speed of each, the drive wheel speed detection unit for detecting the rotation speed of the drive wheel, the rotation speed of the front wheels respectively detected by the front wheel speed detection unit, Steering angle by the potentiometer,
Based on the nominal diameters of the front wheels and the wheel diameter variation coefficient, the target circumferential speed of the drive wheel is calculated, and the circumferential speed detection value of the drive wheel obtained from the detection value by the drive wheel speed detection unit and the A calculation unit that calculates a slip speed calculation value of the drive wheels based on a difference with a target circumferential speed, a ratio between the substantial diameters of the front wheels and the substantial diameter of the drive wheels, and a nominal diameter of the drive wheels. An adjusting unit for adjusting the wheel diameter change coefficient, which is represented by multiplication of the ratio of the front wheels to the nominal diameter and is derived by proportional-plus-integral control based on the slip speed calculation value, is provided. Reach type forklift control device. 2. The wheel diameter change coefficient is derived by a calculation based on a term proportional to the integral of the slip speed calculated value and a term proportional to the slip speed calculated value. The control device for a reach type forklift according to claim 1. 3. The first adjusting unit for the integral term of the slip speed calculation value in the calculation of the wheel diameter change coefficient.
And a second variable coefficient for the proportional term of the slip speed calculated value are made variable depending on whether the slip speed calculated value is positive or negative, and the wheel diameter change coefficient is adjusted by proportional integral control. The controller for a reach type forklift according to claim 2. 4. The reach type forklift according to claim 1, further comprising a control unit that controls a terminal voltage to be supplied to the traveling motor based on the slip speed calculated value. Control device.