JP7534062B2 - Driving control device, driving control method, and driving control program - Google Patents

Description

The present invention relates to a driving control device, a driving control method, and a driving control program, and in particular to a driving control device, a driving control method, and a driving control program for an automatically variable transmission vehicle.

Conventionally, electric vehicles have been controlled to travel by torque control or speed control, as described in Patent Document 1, for example. In torque control, a torque command value is simply determined based on the accelerator operation amount, and the motor is controlled to operate according to this torque command value. For this reason, the torque command value is calculated using only open-loop control, without using feedback control. Therefore, in this torque control, the torque command value is changed according to changes in the accelerator operation amount, and if the accelerator operation amount fluctuates between positive and negative values, the torque command value also fluctuates between positive and negative values. In other words, if the accelerator is operated for forward movement, the motor always performs power running and does not perform regenerative operation.

On the other hand, in the above-mentioned speed control, a target running speed is first calculated based on the accelerator operation amount, a torque command value is calculated based on this target running speed, and the torque command value is corrected, for example, using PI control, so that the deviation between the actual running speed and the calculated target running speed is eliminated. In this speed control, the motor is configured to perform a regenerative operation to reduce the running speed when the calculated target running speed falls below the actual running speed. In this way, the speed control allows the vehicle to run at the running speed intended by the driver. However, in speed control, if the accelerator operation amount increases or decreases quickly due to unevenness of the road surface, the motor may instantly switch between powering operation and regenerative operation. At this time, the vehicle will perform a motion called "pitching," in which it leans forward and backward, and in this respect, the driving feeling of speed control is less preferable than that of torque control.

In speed control, as shown in FIG. 5A, when the driver accelerates the vehicle with the accelerator operation amount at 100%, and when the vehicle reaches a speed of 5 km/h, the driver eases the accelerator operation amount to 50% to drive at 5 km/h. If the driver unintentionally eases the accelerator too much at the speed of 5 km/h (e.g., eases the accelerator operation amount to 30%), the vehicle may decelerate to a speed slower than 5 km/h. Also, as shown in FIG. 5B, when the driver releases the accelerator from the state of 100% accelerator operation amount to decelerate the vehicle to 5 km/h (0% accelerator operation amount), and then steps on the accelerator operation amount to 50% to drive at 5 km/h, if the driver unintentionally steps on the accelerator lightly (e.g., steps on the accelerator operation amount to 30%), the vehicle may decelerate to a speed slower than 5 km/h. In this way, when the vehicle reaches an unintended driving speed, the driver needs to increase or decrease the accelerator operation amount again, and pitching may occur each time. Pitching is a particular problem for loading and unloading vehicles such as forklifts, as it makes the ride even worse than that of regular vehicles and increases the chances of the load falling off the forks.

JP 2003-267698 A

The problem that the present invention aims to solve is to provide a driving control device, a driving control method, and a driving control program that can reduce the occurrence of pitching during driving.

In order to solve the above problems, the driving control device according to the present invention comprises:
A vehicle driving control device having an accelerator, a drive unit, and a driving speed detection unit that detects a driving speed,
a target speed calculation unit that calculates a target driving speed based on an accelerator operation amount;
a control speed setting unit that sets a controlled travel speed;
a holding speed setting unit that sets a holding travel speed;
A drive control unit that drives the drive unit so that the vehicle travels at a controlled travel speed,
When there is no accelerator operation, a predetermined traveling speed is set as a controlled traveling speed and a maintained traveling speed,
When the control travel speed and the held travel speed are set to predetermined travel speeds, if a target travel speed exceeding the predetermined travel speed is calculated, the detected travel speed is set to the control travel speed and the held travel speed;
When the control running speed and the held running speed are not set to predetermined running speeds, if the calculated target running speed is equal to or lower than the held running speed, the control running speed is held at the held running speed.

The driving control device preferably includes:
The predetermined running speed is 0 km/h.

The driving control device preferably includes:
The predetermined running speed is equal to or lower than the running speed at which the creep phenomenon occurs.

The driving control device preferably includes:
When the controlled running speed and the held running speed are not set to predetermined running speeds, if the calculated target running speed exceeds the held running speed, the target running speed is set to the controlled running speed, and as a result, if the running speed increases and exceeds the held running speed, the held running speed is updated to the controlled running speed.

The driving control device preferably includes:
The drive unit is a motor,
The drive control unit causes the motor to perform regenerative operation during deceleration.

The driving control device may, for example,
The vehicle is an industrial vehicle.

The driving control device may, for example,
The vehicle is a loading vehicle.

In order to solve the above problems, a driving control method according to the present invention includes:
A driving control method for driving a vehicle having an accelerator, a drive unit, and a driving speed detection unit that detects a driving speed at a controlled driving speed, comprising:
Calculate a target driving speed based on the accelerator operation amount,
When there is no accelerator operation, a predetermined traveling speed is set as a controlled traveling speed and a maintained traveling speed,
When the control travel speed and the maintained travel speed are set to predetermined travel speeds, if a target travel speed exceeding the predetermined travel speed is calculated, the detected travel speed is set as the control travel speed and the maintained travel speed;
When the control travel speed and the held travel speed are not set to predetermined travel speeds, if the calculated target travel speed is equal to or lower than the held travel speed, the control travel speed is held at the held travel speed.

The driving control method preferably includes:
When the controlled running speed and the held running speed are not set to predetermined running speeds, if the calculated target running speed exceeds the held running speed, the target running speed is set as the controlled running speed, and as a result, if the running speed increases and exceeds the held running speed, the held running speed is updated to the target running speed.

In order to solve the above problems, a driving control program according to the present invention comprises:
The present invention is characterized in that a computer is caused to function as the driving control device.

The driving control device, driving control method, and driving control program of the present invention can reduce the occurrence of pitching during driving.

1 is a side view showing a forklift according to an embodiment of the present invention. 1 is a functional block diagram showing a driving control device according to an embodiment of the present invention; 1A and 1B are diagrams showing a driving control method according to an embodiment of the present invention, in which A shows acceleration and B shows deceleration. FIG. 2 is a diagram showing a flow of a cruise control method according to an embodiment of the present invention. 1A and 1B are diagrams showing a conventional driving control method, in which A shows acceleration and B shows deceleration.

Below, a driving control device 2, a driving control method, and a driving control program according to one embodiment of the present invention will be described with reference to the attached drawings. The vehicle according to this embodiment is a battery-powered forklift 1, but the vehicle according to the present invention is not limited to battery-powered vehicles. The vehicle according to the present invention may be any automatically variable-speed vehicle, and may be, for example, an engine-powered vehicle. Furthermore, the forklift 1 is merely one example, and the vehicle according to the present invention may be, for example, other industrial vehicles or general vehicles.

<Forklift>
First, the configuration of a forklift 1 according to this embodiment will be described with reference to Figures 1 and 2. As shown in Figure 1, the forklift 1 according to this embodiment includes front and rear wheels 10, a vehicle body 11, a mast 12, forks 13, a lifting unit 14, an axle 15, a battery 16, and a motor 17 (see Figure 2). The motor 17 corresponds to the "drive unit" of the present invention. When the present invention is applied to an engine-powered vehicle, the engine corresponds to the "drive unit" of the present invention.

The vehicle body 11 is mounted across the front and rear wheels 10, and the mast 12 extends vertically and is mounted in front of the vehicle body 11. The forks 13 are mounted along the mast 12 so that they can be raised and lowered, and are raised and lowered by a lifting unit 14. The lifting unit 14 is composed of a hydraulic cylinder. The driver O accelerates and decelerates the travel speed Vn of the forklift 1 by operating the accelerator 15 at the driver's feet with his or her foot. Note that the "accelerator" in this invention is a concept that includes an accelerator pedal and an accelerator lever as an "accelerator."

The battery 16 is disposed approximately in the center of the vehicle body 11. The front wheels 10 are drive wheels, and a drive shaft (not shown) is connected to the left and right front wheels 10 and the motor 17. The motor 17 is driven by the power of the battery 16, and drives the front wheels 10 via the drive shaft with the drive torque. The motor 17 can be switched between power running and regenerative operation based on the input torque command value.

As shown in FIG. 2, the forklift 1 further includes a computer (not shown) and a traveling speed detection unit 18. The computer is provided in the vehicle body 11.

The computer has a storage unit, a calculation unit, and a memory (not shown). The storage unit stores a driving control program. The driving control program causes the computer to function as the driving control device 2.

The traveling speed detection unit 18 is configured to detect the traveling speed Vn of the forklift 1. The traveling speed detection unit 18 may detect the traveling speed Vn, for example, by being provided on the drive shaft and detecting the number of rotations of the drive shaft, or by detecting the number of rotations of the motor 17. There are no particular limitations on the method of detecting the traveling speed Vn by the traveling speed detection unit 18. The detected traveling speed Vn is output to the travel control device 2.

<Drive control device>
Next, the configuration of the cruise control device 2 will be described with reference to Fig. 2. The cruise control device 2 has a target speed calculation unit 20, a hold speed setting unit 21, a control speed setting unit 22, and a drive control unit 23.

The target speed calculation unit 20 calculates the target traveling speed Va based on the accelerator operation amount of the driver O. For example, the target speed calculation unit 20 may calculate the target speed by the following formula.

Formula: Va=Vmax×A

Va: Target traveling speed [km/h]
Vmax: Maximum running speed [km/h]
A: Accelerator operation amount [%]

In this embodiment, for the sake of simplicity, the maximum speed of the forklift 1 is set to 10 km/h, and the target speed calculation unit 20 calculates the target traveling speed Va in perfect proportion to the accelerator operation amount. Therefore, for example, when the accelerator operation amount is 100%, the target speed calculation unit 20 calculates the target traveling speed Va to be 10 km/h, and when the accelerator operation amount is 50%, the target traveling speed Va to be 5 km/h. The target traveling speed Va calculated by the target speed calculation unit 20 is output to the holding speed setting unit 21 and the control speed setting unit 22.

The holding speed setting unit 21 sets the holding travel speed Vk. The forklift 1 is configured so that its travel speed Vn is held at the holding travel speed Vk. The holding travel speed Vk set by the holding speed setting unit 21 is output to the control speed setting unit 22.

The control speed setting unit 22 sets the control driving speed Vo. The set control driving speed Vo is output to the drive control unit 23.

The drive control unit 23 drives the motor 17 to travel at the input controlled travel speed Vo. Specifically, the drive control unit 23 calculates a torque command value so that there is no deviation between the controlled travel speed Vo and the travel speed Vn, and outputs the calculated torque command value to the motor 17. The motor 17 is configured to drive according to the input torque command value, so that the forklift 1 travels at the controlled travel speed Vo. The torque command value calculated by the drive control unit 23 may be a positive or negative value, and the motor 17 is configured to perform powering operation when a positive torque command value is input, and to perform regenerative operation when a negative torque command value is input.

<Drive control method>
Next, the driving control method by the driving control device 2 will be specifically described with reference to Fig. 3 and Fig. 4. Fig. 3 is a diagram showing the driving control method according to this embodiment, Fig. 3A shows speed maintenance from acceleration, and Fig. 3B shows speed maintenance from deceleration. As shown in Fig. 3A, the driving control device 2 is configured to maintain the driving speed Vn when the accelerator 15 is released during acceleration. Also, as shown in Fig. 3B, the driving control device 2 is configured to decelerate when the foot is released from the accelerator 15 and the accelerator operation amount becomes 0%, and to maintain the driving speed Vn when the accelerator 15 is pressed down during deceleration.

The operation of the driving control device 2 will be described in more detail below with reference to Figures 3 and 4. As shown in Figure 4, the characters in Figure 4 indicate the following items.
Vo: Controlled driving speed [km/h]
Vn: Detected driving speed [km/h]
Va: Target running speed [km/h]
Vmax: Maximum running speed [km/h]
Vk: Maintained running speed [km/h]
A: Accelerator operation amount [%]
F: Accelerator ON/OFF flag

First, with reference to Figures 3A and 4, we will explain the acceleration control and constant speed control of the cruise control device 2, which accelerates from 0 km/h (stopped state) to 5 km/h.

(1) First, the driver O depresses the accelerator 15 from a stopped state, and the target driving speed Va is calculated by the target speed calculation unit 20 based on the accelerator operation amount (S41). As shown in FIG. 3A, the accelerator operation amount is 100%, so the target driving speed Va is calculated to be 10 km/h.

(2) Next, since the accelerator operation amount is not 0% (No in S42) and the accelerator ON/OFF flag is set to OFF when stopped (No in S43), the accelerator ON/OFF flag is set to ON, the detected travel speed Vn (0 km/h in this case) is set to the maintained travel speed Vk, and this maintained travel speed Vk is set to the controlled travel speed Vo (S44). In other words, when the accelerator 15 is depressed at a speed of 0 km/h, first the accelerator ON/OFF flag is set to ON. At this time, the controlled travel speed Vo is set to 0 km/h, so the forklift 1 does not accelerate yet.

(3) Next, the target speed calculation unit 20 again calculates the target driving speed Va based on the accelerator operation amount (S41). The target driving speed Va is similarly calculated to be 10 km/h.

(4) Next, since the accelerator operation amount is not 0% (No in S42), the accelerator ON/OFF flag is set to ON (Yes in S43), and the target traveling speed Va exceeds the maintained traveling speed Vk (Yes in S45), the accelerator ON/OFF flag is maintained at ON and the calculated target traveling speed Va (10 km/h in this example) is set as the controlled traveling speed Vo (S46). As a result, the drive control unit 23 controls the motor 17 to accelerate the forklift 1 so that the traveling speed Vn becomes 10 km/h.

(5) Furthermore, since the detected running speed Vn exceeds the held running speed Vk (Yes in S47), the running speed Vn is set to the held running speed Vk (S48). As a result, the held running speed Vk increases while being updated to the running speed Vn during acceleration. When the detected running speed Vn is equal to or lower than the held running speed Vk (No in S47), the held running speed Vk is not changed.

(6) Next, when the traveling speed Vn reaches 5 km/h, the driver O reduces the accelerator operation amount from 100% to 0<50%, and the target traveling speed Va based on the accelerator operation amount is calculated by the target speed calculation unit 20 (S41). Note that the maintained traveling speed Vk at this time is set to 5 km/h in S48 of FIG. 4. As shown in FIG. 3A, the accelerator operation amount is 0<50%, so the target traveling speed Va is calculated as 0<5 km/h.

(7) Next, since the accelerator operation amount is not 0% (No in S42), the accelerator ON/OFF flag is set to ON (Yes in S43), and the target driving speed Va does not exceed the held driving speed Vk (No in S45), the accelerator ON/OFF flag is set to ON (held) and the controlled driving speed Vo is set to (held) the held driving speed Vk (S49). Therefore, since the held driving speed Vk is 5 km/h, the controlled driving speed Vo is set to (held) 5 km/h.

As a result, the driver O can maintain the travel speed Vn of the forklift 1 at 5 km/h as long as the accelerator operation amount is maintained at 0<50%. As a result, when the driver O wants to maintain a predetermined travel speed Vn, unlike the conventional method, the driver O can maintain the travel speed Vn with only a small amount of accelerator operation, making driving easier. Moreover, the driver O can easily drive at a constant speed by simply easing up on the accelerator operation amount once the travel speed Vn has increased to the intended travel speed.

Next, referring to Figures 3B and 4, we will explain the deceleration control of the driving control device 2, which decelerates the vehicle from 10 km/h to 5 km/h.

(1) First, when the driving speed Vn is 10 km/h, the driver O releases his/her foot from the accelerator 15 (i.e., the accelerator operation amount is 0%), and the target driving speed Va based on the accelerator operation amount is calculated by the target speed calculation unit 20 (S41). As shown in FIG. 3B, since the accelerator operation amount is 0%, the target driving speed Va is calculated to be 0 km/h.

(2) Next, since the accelerator operation amount is 0% (Yes in S42), the accelerator ON/OFF flag is set to OFF, and the maintained driving speed Vk and the controlled driving speed Vo are set to 0 km/h (S50). As a result, the drive control unit 23 controls the motor 17 so that the driving speed Vn becomes 0 km/h, thereby decreasing the driving speed Vn. The "0" in S50 in FIG. 4 corresponds to the "predetermined driving speed" of the present invention. In this embodiment, the "predetermined driving speed" of the present invention is set to 0 km/h, but this is merely an example, and the "predetermined driving speed" of the present invention may be set to a speed other than 0 km/h, as in a modified example described later.

(3) Next, when the driving speed Vn reaches 5 km/h, the driver O depresses the accelerator 15 with an accelerator operation amount of less than 50%, and the target speed calculation unit 20 calculates the target driving speed Va based on the accelerator operation amount (S41).

(4) Then, since the accelerator operation amount is not 0% (No in S42) and the accelerator ON/OFF flag is not set to ON (No in S43), the accelerator ON/OFF flag is set to ON, the detected traveling speed Vn (i.e., 5 km/h) is set to the held traveling speed Vk, and this held traveling speed Vk is set to the controlled traveling speed Vo (S44). In other words, when the accelerator 15 is depressed during deceleration, the traveling speed Vn at the time when it is depressed (when the accelerator is ON) is set to the controlled traveling speed Vo. Then, in this example, as in the above-mentioned flow, the driver O can maintain the traveling speed Vn of the forklift 1 at 5 km/h by maintaining the accelerator operation amount at 0<50%.

As a result, when the driver O wants to decelerate the driving speed Vn to the intended driving speed, he or she can simply take his or her foot off the accelerator 15 to decelerate, and when the intended driving speed is reached, he or she can simply depress the accelerator 15 to easily drive at the intended driving speed.

As described above, according to the driving control device 2, the driver O does not need to repeatedly make fine adjustments to the accelerator operation amount near the intended driving speed in order to drive at the intended driving speed, as in the past. Therefore, according to the driving control device 2 of the present invention, the forklift 1 can reduce the occurrence of pitching during driving compared to the past. Furthermore, in the case of the conventional constant speed control of general vehicles, a constant speed is separately set, a button for constant speed control is provided, and the vehicle is driven at the constant speed by pressing the button. However, according to the driving control device 2, it is not necessary to set a constant speed or to provide a button for constant speed control. The driving control device 2 can set the constant speed to any driving speed and drive the vehicle at the constant speed simply by operating the accelerator 15.

In addition, according to the cruise control device 2, even if the accelerator operation amount increases or decreases during constant speed driving due to unevenness of the road surface, the so-called dead zone of the accelerator 15 is provided during constant speed driving, so that the driving speed Vn can be stabilized without increasing or decreasing.

The above describes the driving control device 2, driving control method, and driving control program according to one embodiment of the present invention, but the present invention is not limited to the above embodiment. For example, the driving control device, driving control method, and driving control program according to the present invention may be implemented as follows:

<Modification>
The present invention may be applied to a vehicle having creep or pseudo-creep. In this case, the "predetermined running speed" according to the present invention may be 0 km/h, or may be a running speed lower than the running speed during creep. Note that the creep phenomenon here refers to a phenomenon in which a vehicle moves with the engine idling when the accelerator pedal is operated at 0%, and a vehicle having pseudo-creep refers to a vehicle that does not have creep but is set to move at a low speed when the accelerator pedal is operated at 0%.

Reference Signs List 1 Forklift 10 Wheel 11 Vehicle body 12 Mast 13 Fork 14 Lifting unit 15 Axle 16 Battery 17 Motor (drive unit)
18 Travel speed detection unit 2 Travel control device 20 Target speed calculation unit 21 Hold speed setting unit 22 Control speed setting unit 23 Drive control unit Vo Control travel speed Vn Travel speed Va Target travel speed Vmax Maximum travel speed Vk Hold travel speed O Driver

Claims (6)

A vehicle driving control device having an accelerator, a drive unit, and a driving speed detection unit that detects a driving speed,
a target speed calculation unit that calculates a target driving speed based on an accelerator operation amount;
a control speed setting unit that sets a controlled travel speed;
a holding speed setting unit that sets a holding travel speed;
a drive control unit that drives the drive unit so that the vehicle travels at the controlled travel speed,
When the accelerator operation amount is 0% during driving , the driving speed is reduced ,
When the accelerator operation is started, the maintained traveling speed is set to the traveling speed detected at the start of the accelerator operation , and the controlled traveling speed is set to the maintained traveling speed;
When the target travel speed calculated during the operation of the accelerator exceeds the held travel speed, the control travel speed is set to the target travel speed, and as a result, when the travel speed increases and exceeds the held travel speed, the held travel speed is updated to the target travel speed;
A cruise control device comprising: a control unit that holds the controlled cruise speed at the held cruise speed when the target cruise speed calculated during operation of the accelerator is equal to or lower than the held cruise speed. The drive unit is a motor,
The drive control device according to claim 1 , wherein the drive control unit causes the motor to perform a regenerative operation during deceleration. 2. The driving control device according to claim 1 , wherein the vehicle is an industrial vehicle. 2. The travel control device according to claim 1 , wherein the vehicle is a cargo handling vehicle. A driving control method for driving a vehicle having an accelerator, a drive unit, and a driving speed detection unit that detects a driving speed at a controlled driving speed, comprising:
Calculate a target driving speed based on the accelerator operation amount,
When the accelerator operation amount is 0% during driving , the driving speed is reduced ,
When the accelerator operation is started, the detected traveling speed is set to a held traveling speed, and the controlled traveling speed is set to the held traveling speed;
When the target travel speed calculated during the operation of the accelerator exceeds the held travel speed, the control travel speed is set to the target travel speed, and as a result, when the travel speed increases and exceeds the held travel speed, the held travel speed is updated to the target travel speed;
a control step of controlling the controlled traveling speed to be equal to or lower than the maintained traveling speed when the target traveling speed calculated during the operation of the accelerator is equal to or lower than the maintained traveling speed. A cruise control program that causes a computer to function as the cruise control device according to claim 1.

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