Driving control device

Abstract

To provide a travel control device capable of improving the travel stability of a vehicle regardless of the state of wheels.SOLUTION: A travel control device 1 includes: a pair of left and right travel motors 6A, 6B for independently rotationally driving a pair of left and right front wheels 4A, 4B, respectively; an operation amount sensor 21 for detecting an operation amount of a steering wheel 7; a steering angle sensor 22 for detecting a steering angle of rear wheels 5A, 5B; a yaw rate sensor 23 for detecting a turning state of a forklift 2; a travel state determining unit 28 for determining whether or not the forklift 2 is traveling in a direction intended by a driver on the basis of the operation amount of the steering wheel 7, the steering angle of the rear wheels 5A, 5B, and the turning state of the forklift 2; and a drive control unit 29 for controlling the travel motors 6A, 6B to make the forklift 2 travel in the direction intended by the driver, if it is determined that the forklift 2 is not running in the direction intended by the driver.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a cruise control device. [Background technology]

[0002] Known conventional cruise control devices include, for example, the technology described in Patent Document 1. The cruise control device described in Patent Document 1 controls the yaw moment of the vehicle by distributing driving force from a drive source to left and right drive wheels, and also controls the yaw moment of the vehicle by distributing braking force to the left and right wheels. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2011-162145 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above-mentioned conventional technology, if there is an unevenness in the air pressure, wear, ground load, etc. between the left and right wheels, the vehicle may not travel in the direction intended by the driver, leading to a decrease in the vehicle's driving stability.

[0005] An object of the present invention is to provide a driving control device that can improve the driving stability of a vehicle regardless of the state of the wheels. [Means for solving the problem]

[0006] One aspect of the present invention is a driving control device for a vehicle equipped with a pair of left and right drive wheels and steering wheels, and a steering wheel for a driver to steer the steering wheels, the device comprises a pair of left and right drive units that independently rotate and drive the pair of left and right drive wheels, an operation amount detection unit that detects the amount of steering operation, a steering angle detection unit that detects the steering angle of the steering wheels, a turning state detection unit that detects the turning state of the vehicle, a driving state determination unit that determines whether the vehicle is traveling in the direction intended by the driver based on the steering operation amount detected by the operation amount detection unit, the steering angle of the steering wheels detected by the steering angle detection unit, and the turning state of the vehicle detected by the turning state detection unit, and a drive control unit that controls the drive units so that the vehicle travels in the direction intended by the driver when the driving state determination unit determines that the vehicle is not traveling in the direction intended by the driver.

[0007] In such a driving control device, it is determined whether the vehicle is traveling in the direction intended by the driver based on the steering operation amount, the steering angle of the steering wheels, and the turning state of the vehicle. If it is determined that the vehicle is not traveling in the direction intended by the driver, the drive unit is controlled so that the vehicle travels in the direction intended by the driver. Therefore, even if there is an unevenness in the air pressure and wear amount of the pair of left and right drive wheels, the vehicle will travel in the direction intended by the driver. This improves the driving stability of the vehicle regardless of the state of the wheels.

[0008] The turning state detection unit may detect the yaw rate or lateral acceleration of the vehicle, the running state determination unit may determine whether the vehicle is running straight as intended by the driver based on the steering operation amount, the steering angle of the steering wheels, and the yaw rate or lateral acceleration of the vehicle, and the drive control unit may control the drive unit so that the yaw rate or lateral acceleration of the vehicle approaches zero when it is determined that the vehicle is not running straight against the driver's intention. In this configuration, even when the vehicle is not running straight despite the driver's intention to run straight, the yaw rate or lateral acceleration of the vehicle approaches zero, so that the vehicle runs straight. This improves the straight running stability of the vehicle regardless of the state of the wheels.

[0009] The driving state determination unit may determine that the vehicle is not traveling straight despite the driver's intention when at least one of the steering operation amount and the steering angle of the steering wheel is equal to or less than a predetermined first threshold value and the yaw rate or lateral acceleration of the vehicle is greater than a predetermined second threshold value. In this configuration, it is easily determined that the vehicle is not traveling straight despite the driver's intention to travel straight.

[0010] The driving state determination unit may determine that the vehicle is not traveling straight despite the driver's intention when at least one of the steering operation amount and the steering angle of the steering wheel is greater than a predetermined first threshold value and the yaw rate or lateral acceleration of the vehicle is equal to or less than a predetermined second threshold value. In this configuration, it is easily determined that the vehicle is not traveling straight despite the driver's intention to travel straight.

[0011] The driving control device may further include a first notification unit that notifies the driver that a control process is being executed by the drive control unit when the driving state determination unit determines that the vehicle is not driving in the direction intended by the driver. In this configuration, the driver can immediately know that the vehicle is not driving in the direction intended by the vehicle and therefore driving control of the vehicle is being executed.

[0012] The driving control device may further include a wheel state detection unit that records and saves the control amount of the drive unit by the drive control unit in chronological order and detects the state of the drive wheels based on the change in the control amount of the drive unit in chronological order, and a second notification unit that notifies the driver of the state information of the drive wheels detected by the wheel state detection unit. In this configuration, the driver can know the change in the state of the pair of left and right drive wheels. Effect of the Invention

[0013] According to the present invention, the running stability of a vehicle can be improved regardless of the condition of the wheels. [Brief description of the drawings]

[0014] [Figure 1] 1 is a block diagram illustrating a schematic configuration of a cruise control device according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a side view of a forklift to which the travel control device shown in FIG. 1 is applied. [Diagram 3] 4 is a flowchart showing a procedure of a running condition determination process executed by a running condition determination unit shown in FIG. [Figure 4] 1 is a graph showing an example of a state in which it is determined that the forklift is not traveling straight despite the driver's intention. [Diagram 5] 10 is a graph showing another example of a state in which it is determined that the forklift is not traveling straight despite the driver's intention. [Figure 6] 10 is a graph showing yet another example of a state in which it is determined that the forklift is not traveling straight despite the driver's intention. [Figure 7] 10 is a graph showing yet another example of a state in which it is determined that the forklift is not traveling straight despite the driver's intention. [Figure 8] 4 is a flowchart showing a procedure of a drive control process executed by a drive control unit shown in FIG. [Figure 9] FIG. 1 is a conceptual diagram showing how a traveling motor that rotates a pair of left and right front wheels is controlled so that the yaw rate of the forklift becomes zero when the forklift is turning left. [Figure 10] 4 is a flowchart showing the procedure of a notification control process executed by a notification control unit shown in FIG. 1. [Figure 11] FIG. 5 is a block diagram showing a schematic configuration of a cruise control device according to a second embodiment of the present invention. [Figure 12] FIG. 11 is a block diagram showing a schematic configuration of a driving control device according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the drawings, the same or equivalent elements are designated by the same reference numerals, and duplicated explanations will be omitted.

[0016] Fig. 1 is a block diagram showing the configuration of a driving control device according to a first embodiment of the present invention. In Fig. 1, the driving control device 1 of this embodiment is mounted on a forklift 2 (see Fig. 2), which is an industrial vehicle. The driving control device 1 is a device that controls the driving of the forklift 2 when the forklift 2 is being manually operated by a driver.

[0017] As shown in Fig. 2, the forklift 2 includes a body 3, front wheels 4A, 4B (see Fig. 9) which are a pair of left and right drive wheels arranged at the front of the body 3, rear wheels 5A, 5B (see Fig. 9) which are a pair of left and right steering wheels arranged at the rear of the body 3, a pair of left and right travel motors 6A, 6B (see Fig. 1) which rotate the front wheels 4A, 4B independently, a steering wheel 7 which allows the driver to steer the rear wheels 5A, 5B, a loading motor 8 which rotates a hydraulic pump (not shown), and a battery 9 which supplies power to the travel motors 6A, 6B and the loading motor 8. The front wheels 4A, 4B and the rear wheels 5A, 5B are the wheels of the forklift 2. The travel motors 6A, 6B are driving units which rotate the front wheels 4A, 4B.

[0018] The forklift 2 also has a mast 10 erected at the front end of the vehicle body 3, a pair of left and right forks 12 attached to the mast 10 via lift brackets 11 and holding cargo W, a lift cylinder 13 for raising and lowering the forks 12, and a tilt cylinder 14 for tilting the forks 12 via the mast 10. The lift cylinder 13 and tilt cylinder 14 are driven by hydraulic oil from the hydraulic pump (described above).

[0019] The driving control device 1 includes an operation amount sensor 21, a steering angle sensor 22, a yaw rate sensor 23, a tilt angle sensor 24, the driving motors 6A, 6B, an alarm 25, a display 26, and an electronic control unit 27 (ECU: Electronic Control Unit).

[0020] The operation amount sensor 21 is a sensor (operation amount detection unit) that detects the operation amount of the steering wheel 7. The steering angle sensor 22 is a sensor (steering angle detection unit) that detects the steering angle of the rear wheels 5A, 5B that are steered wheels.

[0021] The yaw rate sensor 23 is a sensor that detects the yaw rate of the forklift 2. The yaw rate sensor 23 constitutes a turning state detection unit that detects the turning state of the forklift 2. The inclination angle sensor 24 is a sensor that detects the inclination angle of the road surface on which the forklift 2 is traveling.

[0022] The alarm device 25 generates an alarm sound related to the travel control of the forklift 2. The display device 26 performs screen display and alarm display related to the travel control of the forklift 2. The alarm device 25 and the display device 26 may be configured as a single device.

[0023] The electronic control unit 27 is composed of a CPU, a RAM, a ROM, an input / output interface, etc. The electronic control unit 27 has a running state determination unit 28, a drive control unit 29, and a notification control unit 30.

[0024] The traveling state determination unit 28 determines whether the forklift 2 is traveling in the direction intended by the driver, based on the amount of operation of the steering wheel 7 detected by the operation amount sensor 21, the steering angle of the rear wheels 5A, 5B detected by the steering angle sensor 22, and the yaw rate of the forklift 2 detected by the yaw rate sensor 23. Here, the traveling state determination unit 28 determines whether the forklift 2 is traveling straight as intended by the driver, based on the amount of operation of the steering wheel 7, the steering angle of the rear wheels 5A, 5B, and the yaw rate of the forklift 2.

[0025] The traveling state determination unit 28 determines that the forklift 2 is not traveling straight ahead against the driver's intention when at least one of the operation amount of the steering wheel 7 and the steering angle of the rear wheels 5A, 5B is equal to or less than a predetermined first threshold value and the yaw rate of the forklift 2 is greater than a predetermined second threshold value. A state in which the yaw rate of the forklift 2 is greater than the second threshold value usually corresponds to a state in which the forklift 2 is turning.

[0026] Furthermore, when at least one of the operation amount of the steering wheel 7 and the steering angle of the rear wheels 5A, 5B is greater than the first threshold value and the yaw rate of the forklift 2 is equal to or less than the second threshold value, the traveling state determination unit 28 also determines that the forklift 2 is not traveling straight against the driver's intention. A state in which the yaw rate of the forklift 2 is equal to or less than the second threshold value usually corresponds to a state in which the forklift 2 is not turning.

[0027] 3 is a flowchart showing details of the procedure of the traveling condition determination process executed by the traveling condition determination unit 28. This process is executed, for example, when the forklift 2 is started.

[0028] 3, the traveling state determination unit 28 first obtains the detection values ​​of the operation amount sensor 21, the steering angle sensor 22, and the yaw rate sensor 23 (step S101). Then, the traveling state determination unit 28 determines whether the operation amount of the steering wheel 7 is equal to or less than a specified amount based on the detection value of the operation amount sensor 21 (step S102). The specified amount is a limit value of the operation amount of the steering wheel 7 for driving the forklift 2 straight, and corresponds to the above-mentioned first threshold value.

[0029] When the traveling state determination unit 28 determines that the operation amount of the steering wheel 7 is equal to or less than the specified amount, the traveling state determination unit 28 determines whether the steering angle of the rear wheels 5A, 5B is equal to or less than a specified angle based on the detection value of the steering angle sensor 22 (step S103). The specified angle is the limit value of the steering angle of the rear wheels 5A, 5B for the forklift 2 to travel straight ahead, and corresponds to the above-mentioned first threshold value.

[0030] When the traveling state determination unit 28 determines that the steering angle of the rear wheels 5A, 5B is equal to or smaller than the specified angle, it determines whether or not the yaw rate of the forklift 2 is equal to or smaller than a specified value based on the detection value of the yaw rate sensor 23 (step S104). The specified value is a limit value of the yaw rate at which the forklift 2 does not turn, and corresponds to the above-mentioned second threshold value.

[0031] When the traveling state determination unit 28 determines that the yaw rate of the forklift 2 is equal to or less than the specified value, it determines that the forklift 2 is traveling straight as intended by the driver (step S105). When the traveling state determination unit 28 determines that the yaw rate of the forklift 2 is greater than the specified value, it determines that the forklift 2 is not traveling straight against the driver's intention (step S106).

[0032] When the traveling state determination unit 28 determines in step S103 that the steering angle of the rear wheels 5A, 5B is greater than the specified angle, it determines that the forklift 2 is not traveling straight despite the driver's intention (step S106).

[0033] When the traveling state determination unit 28 determines in step S102 that the operation amount of the steering wheel 7 is greater than the specified amount, the traveling state determination unit 28 determines whether the steering angle of the rear wheels 5A, 5B is greater than a specified angle based on the detection value of the steering angle sensor 22 (step S107). The specified angle is the same value as the specified angle in step S103.

[0034] When the traveling state determination unit 28 determines that the steering angle of the rear wheels 5A, 5B is greater than the specified angle, it determines whether the yaw rate of the forklift 2 is greater than a specified value based on the detection value of the yaw rate sensor 23 (step S108). The specified angle is the same value as the specified angle in step S104.

[0035] When the traveling state determination unit 28 determines that the yaw rate of the forklift 2 is greater than the specified value, it determines that the forklift 2 is traveling straight as intended by the driver (step S105). When the traveling state determination unit 28 determines that the yaw rate of the forklift 2 is equal to or less than the specified value, it determines that the forklift 2 is not traveling straight against the driver's intention (step S106).

[0036] When it is determined in step S107 that the steering angle of the rear wheels 5A, 5B is equal to or smaller than the specified angle, the traveling state determination unit 28 determines that the forklift 2 is not traveling straight ahead against the driver's intention (step S106).

[0037] After step S105 or step S106 is executed, the traveling state determination unit 28 outputs the determination result to the drive control unit 29 and the notification control unit 30 (step S109).

[0038] Through the above-described processing, when the driver is not operating the steering wheel 7 and the steering angle of the rear wheels 5A, 5B is 0 degrees but the forklift 2 is generating a yaw rate, as shown in FIG. 4, it is determined that the forklift 2 is not traveling straight despite the driver's intention to travel straight.

[0039] Also, as shown in FIG. 5, when the driver is not operating the steering wheel 7 but the steering angle of the rear wheels 5A, 5B is larger than the specified angle and a yaw rate of the forklift 2 is occurring, it is determined that the forklift 2 is not traveling straight despite the driver's intention to travel straight.

[0040] On the other hand, as shown in Fig. 6, when the driver is operating the steering wheel 7 and the steering angle of the rear wheels 5A, 5B is larger than the specified angle, but no yaw rate of the forklift 2 is being generated, it is also determined that the forklift 2 is not traveling straight, even though the driver intends to travel straight. For example, when the forklift 2 is traveling on a slope, the driver may operate the steering wheel 7 to make the forklift 2 travel straight. In this case, if the forklift 2 does not turn, the forklift 2 will not travel straight.

[0041] 7, the driver may operate the steering wheel 7 at regular intervals to drive the forklift 2 straight. In this case, the steering angle of the rear wheels 5A, 5B becomes larger than a specified angle at regular intervals, and the forklift 2 does not generate a yaw rate.

[0042] Returning to Figure 1, when the driving state determination unit 28 determines that the forklift 2 is not traveling in the direction intended by the driver, that is, that the forklift 2 is not traveling straight contrary to the driver's intention, the drive control unit 29 controls the traveling motors 6A, 6B based on the detection value of the yaw rate sensor 23 so that the yaw rate of the forklift 2 approaches zero and the forklift 2 travels straight as intended by the driver.

[0043] 8 is a flowchart showing the procedure of the drive control process executed by the drive control unit 29. The execution timing of this process is the same as that of the running state determination unit .

[0044] 8, the drive control unit 29 first determines whether the driving state determination unit 28 has determined that the forklift 2 is not traveling straight against the driver's intention (step S111). When the drive control unit 29 determines that the forklift 2 is not traveling straight against the driver's intention, the drive control unit 29 acquires the detection value of the yaw rate sensor 23 (step S112).

[0045] Then, the drive control unit 29 calculates the drive force of the traveling motors 6A, 6B such that the yaw rate of the forklift 2 becomes zero (step S113). The drive force of the traveling motors 6A, 6B is the torque or rotation speed of the traveling motors 6A, 6B.

[0046] For example, as shown in Fig. 9, when the forklift 2 is turning leftward, the driving force of the travel motor 6A that rotates the left front wheel 4A may be slightly increased (see Fig. 9(a)), or the driving force of the travel motor 6B that rotates the right front wheel 4B may be slightly decreased (see Fig. 9(b)). This causes the forklift 2 to turn rightward.

[0047] Next, the drive control unit 29 outputs a control signal corresponding to the driving force of the traveling motors 6A, 6B to the traveling motors 6A, 6B (step S114). Then, the traveling motors 6A, 6B are driven in response to the control signal. The control signal corresponding to the driving force of the traveling motors 6A, 6B is a control amount used for feedback control of the yaw rate of the forklift 2. As a result, the yaw rate of the forklift 2 approaches zero, and the forklift 2 travels straight ahead.

[0048] When the drive control unit 29 determines in the above step S111 that the forklift 2 is not traveling straight contrary to the driver's intention, that is, when it determines that the forklift 2 is traveling straight as the driver intends, the drive control unit 29 does not execute the above steps S112 to S114.

[0049] Returning to Fig. 1, the notification control unit 30 controls the alarm 25 and the display 26 to notify that a control process by the drive control unit 29 is being executed when the driving state determination unit 28 determines that the forklift 2 is not traveling straight against the driver's intention. The notification control unit 30 cooperates with the alarm 25 and the display 26 to constitute a first notification unit that notifies that a control process by the drive control unit 29 is being executed when the driving state determination unit 28 determines that the vehicle is not traveling in the direction intended by the driver.

[0050] 10 is a flowchart showing the procedure of the notification control process executed by the notification control unit 30. The execution timing of this process is the same as that of the traveling state determination unit .

[0051] In FIG. 10, the notification control unit 30 first determines whether the traveling state determination unit 28 has determined that the forklift 2 is not traveling straight ahead against the driver's intention (step S121).

[0052] When the notification control unit 30 determines that the forklift 2 is not traveling straight despite the driver's intention, it outputs a notification signal to the alarm 25 and the display 26 to the effect that yaw rate control of the forklift 2 is being executed (step S122). Then, an alarm sound is generated from the alarm 25, and an alarm is displayed on the display 26.

[0053] Next, the notification control unit 30 acquires a detection value of the inclination angle sensor 24 (step S123). Then, the notification control unit 30 outputs a display signal including data on the inclination angle of the current road surface on which the forklift 2 is traveling to the display unit 26 (step S124). The current inclination angle of the road surface is then displayed on the display unit 26. This allows the driver to immediately know the current inclination angle of the road surface as well as that yaw rate control of the forklift 2 is being executed.

[0054] When the drive control unit 29 determines in the above step S121 that the forklift 2 is not traveling straight contrary to the driver's intention, that is, when it determines that the forklift 2 is traveling straight as the driver intends, the drive control unit 29 does not execute the above steps S122 to S124.

[0055] However, even though the driver is trying to drive straight, the forklift 2 may not drive straight but may move diagonally against the driver's intention. Causes of the forklift 2 not driving in the direction intended by the driver include uneven air pressure and wear of the left and right front wheels 4A, 4B and rear wheels 5A, 5B, uneven driving force and ground load of the left and right front wheels 4A, 4B which are driving wheels, and the slope (gradient) of the road surface for drainage. Causes of uneven driving force of the left and right front wheels 4A, 4B include uneven torque and gear loss of the front wheels 4A, 4B and output difference between the left and right travel motors 6A, 6B. If the forklift 2 drives against the driver's intention in this way, the driving stability of the forklift 2 will be reduced.

[0056] To address such a problem, in this embodiment, it is determined whether the forklift 2 is traveling in the direction intended by the driver, based on the amount of operation of the steering 7, the steering angle of the rear wheels 5A, 5B which are steered wheels, and the yaw rate of the forklift 2. When it is determined that the forklift 2 is not traveling in the direction intended by the driver, the travel motors 6A, 6B are controlled so that the forklift 2 travels in the direction intended by the driver. Therefore, even if there is an unevenness in the air pressure and wear amount of the front wheels 4A, 4B which are the pair of left and right drive wheels, the forklift 2 travels in the direction intended by the driver. This improves the traveling stability of the forklift 2, regardless of the conditions of the front wheels 4A, 4B and the rear wheels 5A, 5B.

[0057] Furthermore, in this embodiment, when it is determined that the forklift 2 is not traveling straight against the driver's intention, the travel motors 6A, 6B are controlled so that the yaw rate of the forklift 2 approaches zero. Therefore, even when the forklift 2 is not traveling straight despite the driver's intention to travel straight, the yaw rate of the forklift 2 approaches zero, so that the forklift 2 travels straight. This improves the straight-line running stability of the forklift 2 regardless of the state of the front wheels 4A, 4B and rear wheels 5A, 5B.

[0058] In this embodiment, when at least one of the operation amount of the steering wheel 7 and the steering angle of the rear wheels 5A, 5B is equal to or less than the first threshold value and the yaw rate of the forklift 2 is greater than the second threshold value, it is determined that the forklift 2 is not traveling straight despite the driver's intention. Therefore, it is easily determined that the forklift 2 is not traveling straight despite the driver's intention to travel straight.

[0059] In this embodiment, when at least one of the operation amount of the steering wheel 7 and the steering angle of the rear wheels 5A, 5B is greater than the first threshold value and the yaw rate of the forklift 2 is equal to or less than the second threshold value, it is also determined that the forklift 2 is not traveling straight despite the driver's intention. Therefore, it is easily determined that the forklift 2 is not traveling straight despite the driver's intention to travel straight.

[0060] Furthermore, in this embodiment, when it is determined that the forklift 2 is not traveling in the direction intended by the driver, the driver is notified that the yaw rate control process of the forklift 2 is being executed. Therefore, the driver can immediately know that the forklift 2 is not traveling in the direction intended by the driver and therefore the driving control of the forklift 2 is being executed. This can therefore encourage the driver to perform maintenance on the forklift 2 and contribute to prediction of failures of the forklift 2.

[0061] Fig. 11 is a block diagram showing the configuration of a cruise control device according to a second embodiment of the present invention. In Fig. 11, a cruise control device 1A of the present embodiment includes an electronic control unit 27A instead of the electronic control unit 27 in the first embodiment.

[0062] The electronic control unit 27A has the above-mentioned running state determination section 28, the above-mentioned drive control section 29, the above-mentioned notification control section 30, a wheel state detection section 31, and a notification control section 32.

[0063] The wheel state detection unit 31 records and stores the control amounts of the driving motors 6A, 6B by the drive control unit 29 in chronological order, and detects the state of the front wheels 4A, 4B, which are the driving wheels, based on the changes in the control amounts of the driving motors 6A, 6B over time.

[0064] For example, on the same flat road surface, if the driving force of the left traveling motor 6A is controlled to increase in order to bring the yaw rate of the forklift 2 closer to zero, the state of the left front wheel 4A is detected based on the change in the control amount of the traveling motor 6A. Specifically, if the driving force of the traveling motor 6A was controlled to be increased by 1 Nm two months ago, the driving force of the traveling motor 6A was controlled to be increased by 2 Nm one month ago, and the driving force of the traveling motor 6A is controlled to be increased by 3 Nm this time, it will be detected that the air pressure of the front wheel 4A has decreased or the amount of wear on the front wheel 4A has increased.

[0065] The notification control unit 32 controls the display unit 26 to notify the state information of the front wheels 4A, 4B detected by the wheel state detection unit 31. The notification control unit 32 cooperates with the display unit 26 to configure a second notification unit that notifies the state information of the front wheels 4A, 4B detected by the wheel state detection unit 31. As a result, the state of the front wheels 4A, 4B is displayed by the display unit 26.

[0066] In this embodiment, the states of the front wheels 4A, 4B are detected based on the time-series changes in the control amount of the traveling motors 6A, 6B, and the state information of the front wheels 4A, 4B is notified to the driver, so that the driver can know the changes in the state of the pair of left and right front wheels 4A, 4B.

[0067] Fig. 12 is a block diagram showing the configuration of a driving control device according to a third embodiment of the present invention. In Fig. 12, a driving control device 1B of this embodiment includes a lateral acceleration sensor 40 instead of the yaw rate sensor 23 in the above-described first embodiment. The lateral acceleration sensor 40 is a sensor that detects the acceleration in the left-right direction (lateral acceleration) of the forklift 2. The lateral acceleration sensor 40 constitutes a turning state detection unit that detects the turning state of the forklift 2.

[0068] Moreover, the driving control device 1 includes an electronic control unit 27B instead of the electronic control unit 27 in the first embodiment. The electronic control unit 27B includes a driving state determination unit 28B, a drive control unit 29B, and the notification control unit 30.

[0069] The driving state determination unit 28B determines whether the forklift 2 is driving straight as intended by the driver, based on the amount of operation of the steering wheel 7 detected by the operation amount sensor 21, the steering angle of the rear wheels 5A, 5B detected by the steering angle sensor 22, and the lateral acceleration of the forklift 2 detected by the lateral acceleration sensor 40.

[0070] The traveling state determination unit 28B determines that the forklift 2 is not traveling straight ahead against the driver's intention when at least one of the operation amount of the steering wheel 7 and the steering angle of the rear wheels 5A, 5B is equal to or less than a predetermined first threshold value and the lateral acceleration of the forklift 2 is greater than a predetermined second threshold value. A state in which the lateral acceleration of the forklift 2 is greater than the second threshold value usually corresponds to a state in which the forklift 2 is turning.

[0071] Furthermore, when at least one of the operation amount of the steering wheel 7 and the steering angle of the rear wheels 5A, 5B is greater than the first threshold value and the lateral acceleration of the forklift 2 is equal to or less than the second threshold value, the traveling state determination unit 28 also determines that the forklift 2 is not traveling straight ahead against the driver's intention. The state in which the lateral acceleration of the forklift 2 is equal to or less than the second threshold value usually corresponds to a state in which the forklift 2 is not turning.

[0072] When the driving state determination unit 28B determines that the forklift 2 is not driving straight contrary to the driver's intention, the drive control unit 29B controls the traveling motors 6A, 6B based on the detection value of the lateral acceleration sensor 40 so that the lateral acceleration of the forklift 2 approaches zero and the forklift 2 drives straight as intended by the driver.

[0073] In this embodiment, it is determined whether the forklift 2 is traveling in the direction intended by the driver, based on the amount of operation of the steering 7, the steering angle of the rear wheels 5A, 5B which are the steered wheels, and the lateral acceleration of the forklift 2. When it is determined that the forklift 2 is not traveling in the direction intended by the driver, the travel motors 6A, 6B are controlled so that the forklift 2 travels in the direction intended by the driver. As a result, the traveling stability of the forklift 2 is improved, regardless of the conditions of the front wheels 4A, 4B and the rear wheels 5A, 5B, as in the first embodiment.

[0074] The present invention is not limited to the above embodiment. For example, in the above embodiment, the yaw rate sensor 23 or the lateral acceleration sensor 40 is used to determine whether the forklift 2 is traveling in the direction intended by the driver, but the present invention is not particularly limited to such an embodiment. For example, both the yaw rate sensor 23 and the lateral acceleration sensor 40 may be used to determine whether the forklift 2 is traveling straight as intended by the driver, and when it is determined that the forklift 2 is not traveling straight against the driver's intention, the traveling motors 6A, 6B may be controlled so that the yaw rate and lateral acceleration of the forklift 2 approach zero.

[0075] In the above embodiment, it is determined whether the forklift 2 is traveling straight as intended by the driver, and when it is determined that the forklift 2 is not traveling straight against the driver's intention, the travel motors 6A, 6B are controlled so that the forklift 2 travels straight, but the present invention is not limited to such an embodiment. For example, it may be determined whether the forklift 2 is traveling leftward or rightward as the direction intended by the driver, and when it is determined that the forklift 2 is not traveling in the direction intended by the driver, the travel motors 6A, 6B may be controlled so that the forklift 2 travels in the direction intended by the driver.

[0076] In addition, in the above embodiment, travel control is performed for a four-wheel type forklift 2 having a pair of left and right front drive wheels 4A, 4B and a pair of left and right rear steered wheels 5A, 5B. However, the present invention is also applicable to a three-wheel type forklift having one steered rear wheel.

[0077] Furthermore, the present invention can also be applied to vehicles other than industrial vehicles such as forklifts, so long as the vehicle is equipped with a pair of left and right drive wheels, steered wheels, and a steering system. [Explanation of symbols]

[0078] 1, 1A, 1B...driving control device, 2...forklift (vehicle), 4A, 4B...front wheels (driving wheels), 5A, 5B...rear wheels (steered wheels), 6A, 6B...driving motor (driving unit), 7...steering, 21...operation amount sensor (operation amount detection unit), 22...steering angle sensor (steering angle detection unit), 23...yaw rate sensor (turning state detection unit), 25...alarm (first notification unit, second notification unit), 26...display (first notification unit, second notification unit), 28, 28B...driving state determination unit, 29, 29B...driving control unit, 30...notification control unit (first notification unit), 31...wheel state detection unit, 32...notification control unit (second notification unit), 40...lateral acceleration sensor (turning state detection unit).

Claims

1. A vehicle driving control device having a pair of left and right drive wheels and steering wheels, and a steering wheel for a driver to steer the steering wheels, A pair of left and right drive units that independently rotate and drive the pair of left and right drive wheels, respectively; an operation amount detection unit for detecting an operation amount of the steering; A steering angle detection unit that detects a steering angle of the steering wheel; A turning state detection unit that detects a turning state of the vehicle; a driving state determination unit that determines whether the vehicle is driving in a direction intended by a driver based on the steering operation amount detected by the steering operation amount detection unit, the steering angle of the steering wheel detected by the steering angle detection unit, and the turning state of the vehicle detected by the turning state detection unit; and a drive control unit that controls the drive unit so that the vehicle travels in the direction intended by the driver when the driving state determination unit determines that the vehicle is not traveling in the direction intended by the driver, The turning state detection unit detects a yaw rate or a lateral acceleration of the vehicle, the driving state determination unit determines whether the vehicle is driving straight as intended by the driver based on the steering operation amount, the steering angle of the steering wheel, and the yaw rate or lateral acceleration of the vehicle; the drive control unit, when it is determined that the vehicle is not traveling straight against the driver's intention, controls the drive unit so that a yaw rate or a lateral acceleration of the vehicle approaches zero; The driving condition determination unit determines that the vehicle is not traveling straight against the driver's intention when at least one of the steering operation amount and the steering angle of the steering wheel is less than a predetermined first threshold value and the yaw rate or lateral acceleration of the vehicle is greater than a predetermined second threshold value.

2. 2. The driving control device according to claim 1, wherein the driving state determination unit determines that the vehicle is not traveling straight against the driver's intention when at least one of the steering operation amount and the steering angle of the steering wheel is greater than the first threshold value and the yaw rate or lateral acceleration of the vehicle is equal to or less than the second threshold value.

3. A driving control device for a vehicle equipped with a pair of left and right drive wheels and a steering wheel for a driver to steer the steering wheels, A pair of left and right drive units that independently rotate and drive the pair of left and right drive wheels, respectively; an operation amount detection unit for detecting an operation amount of the steering; A steering angle detection unit that detects a steering angle of the steering wheel; A turning state detection unit that detects a turning state of the vehicle; a driving state determination unit that determines whether the vehicle is driving in a direction intended by a driver based on the steering operation amount detected by the steering operation amount detection unit, the steering angle of the steering wheel detected by the steering angle detection unit, and the turning state of the vehicle detected by the turning state detection unit; and a drive control unit that controls the drive unit so that the vehicle travels in the direction intended by the driver when the driving state determination unit determines that the vehicle is not traveling in the direction intended by the driver, The turning state detection unit detects a yaw rate or a lateral acceleration of the vehicle, the driving state determination unit determines whether the vehicle is driving straight as intended by the driver based on the steering operation amount, the steering angle of the steering wheel, and the yaw rate or lateral acceleration of the vehicle; the drive control unit, when it is determined that the vehicle is not traveling straight against the driver's intention, controls the drive unit so that a yaw rate or a lateral acceleration of the vehicle approaches zero; The driving condition determination unit determines that the vehicle is not traveling straight against the driver's intention when at least one of the steering operation amount and the steering angle of the steering wheel is greater than a predetermined first threshold value and the yaw rate or lateral acceleration of the vehicle is equal to or less than a predetermined second threshold value.

4. The driving control device according to any one of claims 1 to 3, further comprising a first notification unit that notifies the driver that a control process is being executed by the drive control unit when the driving state determination unit determines that the vehicle is not traveling in a direction intended by the driver.

5. a wheel state detection unit that records and stores a control amount of the drive unit by the drive control unit in a chronological order and detects a state of the drive wheels based on a change in the control amount of the drive unit in a chronological order; 5. The driving control device according to claim 1, further comprising: a second notification unit that notifies the driver of state information of the drive wheels detected by the wheel state detection unit.

6. A driving control device for a vehicle having a pair of left and right drive wheels and a steering wheel for a driver to steer the steering wheels, A pair of left and right drive units that independently rotate and drive the pair of left and right drive wheels, respectively; an operation amount detection unit for detecting an operation amount of the steering; A steering angle detection unit that detects a steering angle of the steering wheel; A turning state detection unit that detects a turning state of the vehicle; a driving state determination unit that determines whether the vehicle is driving in a direction intended by a driver based on the steering operation amount detected by the steering operation amount detection unit, the steering angle of the steering wheel detected by the steering angle detection unit, and the turning state of the vehicle detected by the turning state detection unit; and a drive control unit that controls the drive unit so that the vehicle travels in the direction intended by the driver when the driving state determination unit determines that the vehicle is not traveling in the direction intended by the driver; a wheel state detection unit that records and stores a control amount of the drive unit by the drive control unit in a chronological order and detects a state of the drive wheels based on a change in the control amount of the drive unit in a chronological order; a notification unit that notifies state information of the drive wheels detected by the wheel state detection unit.

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