JP2007186085A - Steering control device of industrial vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide technology to realize favorable steering feeling by properly setting dead zone width. <P>SOLUTION: This steering control device of an industrial vehicle is furnished with a steering wheel detecting means to detect a steering wheel angle, a steering detecting means to detect a steered angle, a computing means to compute an angle difference of the steering wheel angle and the steered angle, a dead zone setting means to set the width of the dead zone where output of a motor for steering against the angle difference becomes zero and an output computing means to compute output of the motor for steering from the angle difference and the dead zone width. The dead zone setting means finds steering wheel speed by differentiating the steering wheel angle, reduces the dead zone width when this steering wheel speed is not zero and increases the dead zone width when the steering wheel speed is zero and the motor for steering is in the middle of output. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an industrial vehicle steering control device that operates a steering motor in accordance with a rotation operation of a handle.

2. Description of the Related Art Conventionally, some industrial vehicle steering control devices control the output of a steering motor in accordance with a deviation (angle difference) between a rotation angle of a steering wheel and a rotation angle of a steering wheel, as shown in Patent Document 1, for example. In some cases, a dead zone in which the output of the steering motor is 0 with respect to the deviation (angle difference) is provided. Also, as shown in Patent Document 2, for example, there is one that controls the output of the steering motor in accordance with the rotation angle of the handle, and a dead zone is provided in which the output of the steering motor is zero centering on the neutral state of the handle. Has been done.
Although the width of the dead zone provided in this way may be fixed to a constant value, the technique of Patent Document 1 changes the dead band width according to the deviation speed, and the technique of Patent Document 2 sets the dead band width. A small width is set during operation of the handle, and a large width is set during non-operation. In addition to this, as shown in Patent Document 3, there is a technique for calculating the dead zone width using the traveling speed and the steering speed of the vehicle.

JP 2001-63603 A JP 2003-118606 A JP 2004-9838 A

  An object of the present invention is to provide a technique for appropriately setting a dead zone width and realizing a good steering feeling in place of the conventional technique.

  In order to achieve the above object, the present invention provides a steering control device for an industrial vehicle that operates a steering motor in accordance with a rotation operation of a steering wheel and rotates a steering wheel with the steering motor to change its direction. Steering wheel detecting means for detecting a steering wheel angle which is a rotational angle of the steering wheel; Speed calculating means for calculating a steering wheel speed by differentiating the steering wheel angle; and steering for detecting a steering angle which is a rotational angle of the steering wheel Detecting means; angle difference calculating means for calculating an angle difference between the steering wheel angle and the steering angle; a dead zone setting means for setting a dead band width at which the output of the steering motor with respect to the angle difference is zero; and Output calculating means for calculating the output of the steering motor from the angle difference and the dead zone width, and the dead zone setting means has the steering wheel speed Otherwise, the dead zone width is reduced at a predetermined first reduction rate, the dead zone width is increased at a predetermined increase rate if the steering wheel speed is 0 and the steering motor is outputting. It is the structure characterized by being.

According to the present invention as described above, when the steering wheel speed is not zero, that is, when the steering wheel is being rotated, the dead zone width is reduced, so that the steering wheel rotates quickly with respect to the steering wheel rotating operation. A light steering feeling can be obtained. Also, if the steering wheel speed is 0, that is, the steering wheel is held or stopped, and if the steering motor is outputting, the dead zone width will increase and the angle difference will quickly fall within the dead zone. And the output of the steering motor becomes zero. Therefore, it is possible to prevent the steering motor from being quickly stopped and prevent the steering motor from continuing to output unnecessary, and to provide a steering feeling that can easily maintain the direction of the vehicle by not rotating the steering wheel. Can do.
Note that the dead zone width is reduced when the range of the angle difference at which the output of the steering motor becomes 0 approaches 0, and conversely when it is increased, the angle difference at which the output of the steering motor becomes 0. The range is going away from zero.

  In the above configuration, the increase rate may be set to a smaller value as an absolute value than the first decrease rate.

  In this way, the dead zone width can be reduced relatively quickly, while the dead zone width can be increased at an appropriate speed. As a result, the lightness of the steering feeling can be further increased, and the sudden stop of the steering motor can be prevented.

  Further, in the above configuration, in the case of including a travel detection unit that detects the travel state of the industrial vehicle, the dead zone setting unit determines whether or not the vehicle is traveling based on a signal from the travel detection unit. If it is determined that the vehicle is traveling, the dead zone width can be reduced at the first reduction rate.

  In this way, the dead zone width is reduced during traveling, so that it is possible to travel while changing the direction of the vehicle by quickly rotating the steering wheel in response to the steering operation. In addition, what is necessary is just to be able to detect driving | running | working states, such as the rotation speed of the wheel provided in the industrial vehicle, and the rotation speed of the motor which drives a wheel as a driving | running | working detection means.

  In the above configuration, the dead zone setting means sets the dead zone width as the first reduction rate unless it is determined that the vehicle is traveling unless the steering wheel speed is 0 and the steering motor is outputting. When it is determined that the vehicle is traveling while reducing at a different second reduction rate, the dead zone width is reduced at the first reduction rate, and the second reduction rate is more absolute than the first reduction rate. The value can be set to a small value.

  In this way, the dead zone width is reduced when the vehicle is not running, the steering wheel is not operated, and the steering motor is not being output, so that when the steering wheel operation is resumed, the dead zone is reduced. It can be a light steering feeling. However, since the second reduction rate is smaller than the first reduction rate as an absolute value, the rate at which the dead zone width is reduced is smaller than that during traveling, and gradually decreases. Therefore, if the dead zone width starts to decrease at the second reduction rate and the driving is restarted at an early stage, the dead zone width is relatively large, and a steering feeling that can easily maintain the vehicle orientation is obtained. be able to. On the other hand, the ratio of the dead zone width to be reduced during traveling is large and the reduction progresses quickly, so that a light steering feeling can be achieved quickly.

  In the above configuration, the second decrease rate may be set to the same value as the increase rate and as an absolute value.

  Further, in the above configuration, the dead zone setting means determines that the handle speed is not 0 when the handle speed calculated by the speed calculation means is larger than 0 as an absolute value, and then calculated by the speed calculation means. If the handle speed is determined to be zero when a predetermined time has elapsed when the handle speed is zero, the handle speed is immediately zero even if the result of differential calculation of the handle angle is zero. Since it is not determined that there is, it is possible to prevent the reduction and expansion of the dead zone width from being repeated frequently.

  As described above, according to the present invention, when the steering wheel is being rotated, the dead zone width can be reduced to provide a light steering feeling. If the steering motor is outputting when the steering wheel is held or the operation is stopped, the dead zone width increases and the steering motor can be quickly stopped.

  Hereinafter, an embodiment in which the present invention is applied to a forklift will be described with reference to the drawings.

  As shown in FIG. 1, the forklift according to this embodiment includes a pair of left and right straddle legs 2 extending rearward at the rear part of a vehicle body 1, and a rear wheel 3 is provided at the front end part of each straddle leg 2. ing. A front wheel 4 is provided at the center of the front portion of the vehicle body 1, and the front wheel 4 functions as a drive wheel and a steering wheel as will be described later. A mast 5 is erected on the rear part of the vehicle body 1, and a cab 6 is supported on the mast 5 so as to be movable up and down. The cab 6 includes a pair of left and right forks 7 extending rearward, and an operation box 8 for raising and lowering the cab 6 and a front wheel 4 are rotated as drive wheels on the front wall of the cab 6. An accelerator 9 for adjusting the traveling speed and a handle 10 for rotating the front wheel 4 as a steering wheel and changing its direction are provided.

As shown in FIG. 2, the front wheel 4 is supported by a drive device 11 provided on the vehicle body 1 so as to be rotatable about a vertical axis, and a traveling motor for driving the front wheel 4 is disposed above the drive device 11. 12 and a steering motor 13 for driving the drive device 11 are installed.
The front wheel 4 and the traveling motor 12 are connected via a gear built in the drive device 11, and the driving torque from the traveling motor 12 is transmitted to the front wheel 4 via the drive device 11, and the front wheel 4 rotates. To do. The drive device 11 and the steering motor 13 are also connected via a gear different from the above, and the drive torque from the steering motor 13 is transmitted to the drive device 11 so that the drive device 11 rotates. Here, since the front wheel 4 is supported by the drive device 11 as described above, the front wheel 4 and the drive device 11 rotate integrally. These motors are controlled by a control device 14 mounted on the vehicle body 1.

  As shown in FIG. 2, the handle 10 is provided with an angle sensor 10 </ b> A composed of a potentiometer, and a signal indicating the rotation angle (handle angle) of the handle 10 is input to the control device 14 from the angle sensor 10 </ b> A. An angle sensor 11A composed of a potentiometer is connected to a gear fixed to the drive device 11 among the gears connecting the drive device 11 and the steering motor 13, and the rotation angle (steering angle) of the front wheel 4 is connected to the angle sensor 11A. ) Is input to the control device 14. Further, the traveling motor 12 includes a speed sensor 12 </ b> A that includes an encoder, and a signal (traveling signal) indicating the rotational speed of the traveling motor 12 is input from the speed sensor 12 to the control device 14.

  As shown in FIG. 3, the control device 14 includes a handle speed calculating unit 141 that calculates a handle speed ΔH from a handle angle H detected by the angle sensor 10A, a handle angle H detected by the angle sensor 10A, and the angle sensor 11A. A deviation angle calculation unit 142 that calculates a deviation angle G that is an angle difference from the steering angle S detected in step S3, a dead band setting unit 143 that sets the width of the dead band in which the output value D of the steering motor 13 is 0, An output setting unit 144 that sets the output value D of the steering motor 13 and a control unit 145 that controls the steering motor 13 with the output value D are provided.

  The handle speed calculation unit 141 obtains the handle speed ΔH by time-differentiating the handle angle H from the angle sensor 10A and transmits the handle speed ΔH to the dead zone setting unit 143. The deviation angle calculation unit 142 obtains a deviation angle G (= HS) using the steering wheel angle H from the angle sensor 10A and the steering angle S from the angle sensor 11A, and uses the deviation angle G as a dead zone setting unit 143. To tell.

  The dead zone setting unit 143 sets the dead zone width B according to the steering wheel speed ΔH from the steering wheel speed calculation unit 141, the deviation angle G from the deviation angle calculation unit 142, and the travel signal from the speed sensor 12A, and the output setting unit 144. The output value D is set to 0 when the deviation angle G is in the dead zone. Then, the control unit 145 stops the steering motor 13 when the output setting unit 144 sets the output value D = 0.

  Hereinafter, the flow of control in the control device 14 will be further described with reference to FIGS. 4A, 4B and FIG.

As shown in FIG. 4A, a travel signal is input from the speed sensor 12A to the control device 14 (S1), a steering wheel angle H is input from the angle sensor 10A (S2), and a steering angle S is input from the angle sensor 11A. (S3).
The steering wheel speed calculation unit 141 calculates the steering wheel speed ΔH from the steering wheel angle H (S4), and the dead zone setting unit 143 obtains the steering wheel speed magnitude | ΔH | (hereinafter referred to as steering wheel speed | ΔH |), and | ΔH |> 0. It is determined whether or not (S5). If the handle speed | ΔH |> 0, the dead zone setting unit 143 clears the elapsed time T (S6) and turns on the handle rotation flag (S7). If the handle speed | ΔH |> 0 is not satisfied, the dead zone setting unit 143 counts the elapsed time T (S8), and whether the elapsed time T exceeds the predetermined OFF determination time Toff, that is, whether the elapsed time T> Toff. It is determined whether or not (S9). If the elapsed time T> Toff, the dead zone setting unit 143 turns off the handle rotation flag (S10).

  Subsequently, the deviation angle calculation unit 142 calculates a deviation angle G from the steering wheel angle H and the steering angle S (S11), and the dead zone setting unit 143 compares the deviation angle G with the maximum value Gmax, and the deviation angle G> Gmax. It is determined whether or not (S12). If the deviation angle G> Gmax, the dead zone setting unit 143 updates the maximum value Gmax with the deviation angle G obtained in S11 (S13). If the deviation angle G> Gmax is not satisfied, the process proceeds directly to the next process.

As shown in FIG. 4B, the dead zone setting unit 143 determines whether the steering wheel rotation flag is on (S14) and whether the vehicle is traveling (S15). Whether or not the vehicle is traveling is determined based on a traveling signal from the speed sensor 12A. The dead zone setting unit 143 determines that the vehicle is stopped if the rotational speed of the traveling motor 12 is 0, and the traveling motor 12 If the number of rotations is not 0, it is determined that the vehicle is traveling.
If the steering wheel rotation flag is either on or running, the dead zone setting unit 143 reduces the dead zone width B by a predetermined reduction rate R1 (R1 <0) and approaches 0 ( S16). If the steering wheel rotation flag is not on and the vehicle is not traveling, the dead zone setting unit 143 determines whether or not the steering motor 13 is outputting (S17). If output is in progress, the dead zone width B is enlarged at a predetermined rate of increase R2 (R2> 0, | R2 | <| R1 |), and is moved away from 0 (S18). If not, the dead zone setting unit 143 reduces the dead zone width B by a predetermined reduction rate R3 (R3 <0, | R3 | <| R1 |) and approaches 0 (S19).

  If the process of reducing the dead band width B in S16 or S19 continues continuously, the dead band width B is reduced to the minimum value Bmin, for example, as shown in FIG. 5A, and the process of expanding the dead band B in S18 is continued. If it continues to this, as shown in FIG.5 (b), for example, the dead zone width B will expand to the maximum value Bmax. FIG. 5A shows a case where the dead zone width B is reduced from the maximum value Bmax to the minimum value Bmin, and the slopes of the thick straight lines in the figure indicate the reduction rate R1 and the reduction rate R3, respectively. Similarly, FIG. 5B shows a case where the dead zone width B expands from the minimum value Bmin to the maximum value Bmax, and the slope of the thick straight line in the figure indicates the increase rate R2.

  When the dead band width B is thus set, the output setting unit 144 calculates the output value D of the steering motor 13 using the dead band width B (S20).

As shown in FIG. 6, the output setting unit 144 determines whether or not the deviation angle G is in the dead band, that is, the magnitude of the deviation angle G | G | (hereinafter, the deviation angle | G |) is 1 of the dead band B. It is determined whether it is equal to or less than / 2 (S20-1). If the deviation angle | G | ≦ B / 2, the output setting unit 144 sets the output value D = 0 (S20-2). If the deviation angle | G | ≦ B / 2 is not satisfied, the deviation angle G is the dead band B. It is judged whether it is larger than 1/2 of (S20-3). If G> B / 2, the output setting unit 144 sets the output value D = (GB−2) × K (S20-4), and if G> B / 2, the output value D = (G + B / 2). It is set as xK (S20-5). Here, K is a proportionality coefficient.
Further, the output setting unit 144 compares the output value D thus obtained with the upper limit value Dmax, and determines whether or not the output value D> Dmax (S20-6). If the output value D> Dmax, the output setting unit 144 sets the output value D = Dmax (S20-7). If the output value D> Dmax is not satisfied, the output value D is compared with the lower limit value -Dmax. Then, it is determined whether or not the output value D <−Dmax (S20-8). If the output value D <−Dmax, the output setting unit 144 sets the output value D = −Dmax (S20-9). If the output value D <−Dmax is not satisfied, the process proceeds directly.

Accordingly, as shown in FIG. 7, the dead zone width B is set to a value between the minimum value Bmin and the maximum value Bmax. If the deviation angle G is within the dead zone, the output value D is 0, and the deviation angle G is the dead zone. If it is outside, the output value D becomes a value proportional to the deviation angle G in a range not exceeding the upper limit value Dmax and the lower limit value −Dmax.
The minimum value Bmin is set in advance, and the maximum value Bmax is twice the maximum value Gmax of the deviation angle G. Therefore, the maximum value Bmax expands with the update of the maximum value Gmax.

  When the output value D is calculated in this way, as shown in FIG. 4B, the control unit 145 controls the steering motor 13 with the output value D (S21). The control unit 145 rotates the steering motor 13 forward if the output value D is a positive value, reverses the steering motor 13 if the output value D is a negative value, and if the output value D is 0. The steering motor 13 is stopped.

  According to such an embodiment, the dead zone width B is reduced during the rotation operation of the handle 10, so that a light steering feeling can be obtained in which the front wheels 4 rotate quickly in response to the rotation operation of the handle 10. be able to. Further, if the steering wheel motor 13 is outputting power when the steering wheel speed ΔH is 0, that is, when the steering wheel 10 is held or the operation of the steering wheel 10 is stopped, the dead zone width B increases. The deviation angle G quickly becomes a value within the dead zone, and the output value D becomes zero. Therefore, the steering motor 13 can be quickly stopped to prevent the steering motor 13 from continuing to output unnecessarily, and the steering feeling can easily maintain the direction of the forklift without rotating the front wheels 4. it can.

  Furthermore, according to the above embodiment, the dead zone width B is reduced during traveling, so that the front wheel 4 can be quickly rotated in response to the rotation operation of the handle 10 to change the direction of the forklift. It becomes like this. Here, the rate of reduction of the dead zone B during traveling is large and the reduction progresses quickly, so that it is possible to quickly and lighten the steering feeling. If the vehicle is not running, the steering wheel 10 is not being operated, and the steering motor 13 is not being output, the dead zone B is reduced, so that when the steering wheel 10 is resumed, the dead zone B is operated in a relatively small state. Thus, a light steering feeling can be obtained. However, since the rate of reduction of the dead band B is smaller than that during traveling and gradually decreases, if the driving is resumed at an early stage after the dead band B starts to decrease, the dead band B is relatively large. As a result, it is possible to provide a steering feeling that can easily maintain the direction of the forklift.

  In addition, when the state where the steering wheel speed ΔH is 0 continues for the OFF determination time Toff, the steering wheel rotation flag is turned off by determining that the steering wheel speed ΔH is 0. It is prevented that the reduction and enlargement of the width B are repeated frequently.

1 is a perspective view of a forklift according to an embodiment of the present invention. 1 is a schematic diagram of a steer-by-wire system according to an embodiment of the present invention. It is a functional block diagram of the Example of this invention. It is a control flowchart of the Example of this invention. It is a control flowchart of the Example of this invention. It is a control characteristic figure of the Example of this invention, (a) shows reduction of a dead zone width, (b) shows expansion of a dead zone width. It is a control flowchart of the Example of this invention. It is a control characteristic figure of the Example of this invention.

Explanation of symbols

4 Front Wheel 10 Handle 10A Angle Sensor 11 Drive Device 11A Angle Sensor 12 Traveling Motor 12A Speed Sensor 13 Steering Motor 14 Control Device 141 Handle Speed Calculation Unit 142 Deviation Angle Calculation Unit 143 Dead Band Setting Unit 144 Output Setting Unit

Claims (4)

A steering control device for an industrial vehicle that operates a steering motor in accordance with a rotation operation of a steering wheel, rotates a steering wheel with the steering motor, and changes the direction of the steering wheel.
Steering wheel detection means for detecting a steering wheel angle which is a rotation angle of the steering wheel; speed detection means for calculating a steering wheel speed by differentiating the steering wheel angle; Means, angle difference calculating means for calculating an angle difference between the steering wheel angle and the steering angle, a dead zone setting means for setting a dead zone width at which the output of the steering motor with respect to the angle difference is zero, and the angle Output calculating means for calculating the output of the steering motor from the difference and the dead zone width;
The dead zone setting means reduces the dead zone width at a predetermined first reduction rate if the steering wheel speed is not zero, and is predetermined if the steering wheel speed is zero and the steering motor is outputting. A steering control device for an industrial vehicle, characterized in that the dead zone width is expanded at an increase rate of.   2. The industrial vehicle steering control device according to claim 1, wherein the increase rate is set to a value smaller than the first decrease rate as an absolute value. Comprising travel detection means for detecting the travel state of the industrial vehicle;
The dead zone setting means determines whether or not the vehicle is traveling based on a signal from the travel detection means, and if it is determined that the vehicle is traveling, the dead zone width is reduced by the first reduction rate. The industrial vehicle steering control device according to claim 1 or 2. The dead zone setting means sets the dead zone width to a second reduction rate different from the first reduction rate unless it is determined that the vehicle is traveling unless the steering wheel speed is 0 and the steering motor is outputting. When it is determined that the vehicle is traveling, the dead zone width is reduced at the first reduction rate.
The industrial vehicle steering control device according to claim 3, wherein the second reduction rate is set to a value smaller than the first reduction rate as an absolute value.

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