JP4508795B2 - Vehicle travel control device - Google Patents

Description

  The present invention relates to a travel control device for a vehicle such as a transport vehicle.

  In general, when a vehicle turns sharply at high speed, the vehicle becomes unstable due to the centrifugal force acting on the vehicle. Since there is a risk of such a sudden turning operation in a vehicle operated by the driver, for example, as shown in Patent Document 1, the traveling speed is reduced to suppress centrifugal force during turning, thereby stabilizing the vehicle. It is done to keep on. In addition, as shown in Patent Document 2, a technique for reducing the traveling speed by controlling the output of the drive device according to the steering angle (steering angle) of the steered wheel (steering wheel) only during reverse travel has been proposed. . Furthermore, since it is considered that the start from the state in which the steered wheel is steered is a sudden start in an unexpected direction, for example, as shown in Patent Document 3, the steered wheel has a steering angle (turning angle) of a predetermined angle. A technique for suppressing acceleration when the above is true has also been proposed.

  In addition to the vehicles described in Patent Document 2 and Patent Document 3, for example, there is a transport vehicle as shown in Patent Document 4, and this type of transport vehicle mainly includes markets and factories. Used to carry luggage on premises.

Japanese Utility Model Publication No. 57-65506 JP 2001-339813 A JP 2003-171095 A Japanese Utility Model Publication No. 53-39929

  According to the above conventional technology, the vehicle stability is ensured by reducing the traveling speed or suppressing acceleration during turning. Will drop. In addition, it may be stressed for the driver, for example, the driving feeling deteriorates.

  Therefore, an object of the present invention is to perform travel control more appropriately during turning, to ensure the stability of the vehicle, and to achieve good operability for the driver.

  In order to achieve the above object, a first aspect of the present invention is a travel control device that controls a drive device that travels and drives the drive wheel in a vehicle including a drive wheel that travels and a steering wheel that performs steering. Speed detecting means for detecting the traveling speed of the vehicle, steering angle detecting means for detecting the steering angle of the steered wheels, steering direction determining means for determining the steering direction of the steered wheels, and Steering angle determination means for determining whether or not a predetermined angle range centered on an angle when the wheel is in a straight traveling state; angle range changing means for changing the angle range according to the steering direction; Drive control means for suppressing and controlling the output of the drive device so that the traveling speed is less than or equal to a predetermined value when the steering angle is not within the angle range, and the angle range changing means has the steering direction Go straight on the steering wheel When a direction to approach the state, has a configuration to change widely the angle range than when a direction away from the straight traveling state.

According to such a configuration, when the angle range in which the suppression control of the drive device that makes the traveling speed equal to or less than the predetermined value is performed is changed according to the steering direction, and the steering direction is a direction to move the steered wheel away from the straight traveling state, When the angle range is set to be relatively narrow and the steering direction is a direction in which the steered wheels are brought close to a straight traveling state, the angle range is set to be wider than the angle range described above. Therefore, when the steered wheel is steered in a direction away from the straight traveling state, the suppression control starts to be performed from a relatively small steered state with respect to the straight traveling state, and continues to be performed even when the steering wheel is largely steered. On the other hand, when the steered wheel is steered in a direction approaching the straight traveling state, the suppression control is performed in a relatively steered state based on the straight traveling state, but the suppression control is not performed in a small steered state.
In other words, the direction in which the steered wheels are moved away from the straight traveling state is a direction in which the centrifugal force accompanying the turn gradually increases even when the traveling speed is unchanged, so that the vehicle can be controlled by controlling the drive device even in a relatively small steered state. It will be possible to run while preventing instability. On the other hand, the direction in which the steered wheels are brought close to the straight traveling state is a direction in which the centrifugal force accompanying the turning gradually decreases even when the traveling speed is unchanged, and therefore the suppression control of the drive device is not performed in a relatively small steered state. The vehicle can travel in a stable state without unnecessarily reducing the traveling speed.

  The drive control means can control the drive device so that the traveling speed is equal to or less than a predetermined value corresponding to the steering angle. The farther away the steering angle is from the angle range where the suppression control is performed, that is, the steering wheel. It is possible to set the predetermined value to a smaller value as the distance from the angle when the vehicle is in the straight traveling state is further away.

  In order to achieve the above object, the second aspect of the present invention is a travel control device for controlling a drive device for driving the drive wheel in a vehicle having a drive wheel for traveling and a steering wheel for steering. A steering angle detecting means for detecting a steering angle of the steered wheel, a steering direction determining means for determining a steering direction of the steered wheel, and an angle when the steered angle causes the steered wheel to go straight. When the steering angle is not within the angle range, steering angle determination means for determining whether or not the angle is within a predetermined angle range, angle range change means for changing the angle range according to the steering direction, and Driving control means for suppressing and controlling the output of the driving device so that the traveling acceleration of the vehicle becomes a predetermined value or less, and the angle range changing means makes the steering direction bring the steered wheel closer to a straight traveling state. When the direction is It has a configuration to change widely the angle range than when a direction away from the advance state.

According to such a configuration, when the angle range in which the suppression control of the drive device that makes the traveling acceleration equal to or less than the predetermined value is performed is changed according to the steering direction, and the steering direction is a direction to move the steering wheel away from the straight traveling state, When the angle range is set to be relatively narrow and the steering direction is a direction in which the steered wheels are brought close to a straight traveling state, the angle range is set to be wider than the angle range described above. Therefore, when the steered wheel is steered in a direction away from the straight traveling state, the suppression control starts to be performed from a relatively small steered state with respect to the straight traveling state, and continues to be performed even when the steering wheel is largely steered. On the other hand, when the steered wheel is steered in a direction approaching the straight traveling state, the suppression control is performed in a relatively steered state based on the straight traveling state, but the suppression control is not performed in a small steered state.
In other words, the direction in which the steered wheel is moved away from the straight traveling state is a direction in which the centrifugal force accompanying the turning gradually increases even when the traveling speed is unchanged, so that the suppression control of the drive device is performed even in a relatively small steered state. This makes it possible to travel while preventing the vehicle from becoming unstable without causing a large change in travel speed. On the other hand, the direction in which the steered wheels are brought close to the straight traveling state is a direction in which the centrifugal force accompanying the turning gradually decreases even when the traveling speed is unchanged, and therefore the suppression control of the drive device is not performed in a relatively small steered state. The vehicle can travel in a stable state without unnecessarily lowering the traveling acceleration.

  The drive control means can control the drive device so that the travel acceleration is equal to or less than a predetermined value corresponding to the steering angle. The farther away the steering angle is from the angle range where the suppression control is performed, that is, the steering wheel. It is possible to set the predetermined value to a smaller value as the distance from the angle when the vehicle is in the straight traveling state is further away.

  In the first and second aspects of the invention, the vehicle includes forward / reverse determination means for determining whether the traveling direction of the vehicle is the forward direction or the reverse direction, and the angle range changing means is configured so that the traveling direction is the reverse direction. In this case, the angle range can be changed to be narrower than that in the forward direction.

  According to this, by narrowing the angle range in which the traveling speed or the traveling acceleration is not suppressed at the time of reverse driving with a higher degree of danger, the traveling speed or the traveling acceleration is suppressed from a relatively small steering angle, so that the vehicle Can improve the safety. On the other hand, since the danger level is lower at the time of forward travel than at the time of reverse travel, the travel speed or travel acceleration is not suppressed more than necessary while ensuring safety by widening the angle range in which travel speed or travel acceleration is not suppressed. Can be. As described above, by appropriately setting the conditions for suppressing the traveling speed or the traveling acceleration at the time of forward travel and at the time of reverse travel, both improvement in safety and convenience of the vehicle can be obtained.

  In addition, the vehicle according to the first and second inventions includes a front wheel that serves as a driving wheel and a steering wheel, a rear wheel as a driven wheel, and a loading platform at a position above the rear wheel. In the case of a transport vehicle including a driver's cab on which the driver is boarded at a position in front of the cargo bed, the steering angle detection means detects the steering angle of the front wheel, and the steering direction determination means includes The steering direction of the front wheel may be determined.

  According to the first aspect of the invention, when the steered wheel is steered away from the straight traveling state, the suppression control is performed from a relatively small steered state based on the straight traveling state. On the other hand, when the steered wheel is steered in a direction approaching a straight traveling state, the suppression control is not performed in a relatively small steered state, so the travel speed is not reduced unnecessarily. Can run.

  According to the second aspect of the present invention, when the steered wheel is steered away from the straight traveling state, the suppression control is performed from a relatively small steered state based on the straight traveling state, so that a large change in traveling speed can be achieved. On the other hand, when the steering wheel is steered in a direction approaching a straight traveling state, the suppression control is not performed in a relatively small steered state, and therefore the travel acceleration is unnecessarily increased. You can drive without lowering.

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

  As shown in FIGS. 1 and 2, the electric transport vehicle according to this embodiment (embodiment 1) includes a device storage chamber 2 in the front portion of the vehicle body 1, and a driver's cab 3 on which a driver gets on the rear position. And a backrest 4 at the rear end of the cab 3, and further a loading platform 5 on which a load is placed. A battery 6 is mounted on the vehicle body 1 at a position below the loading platform 5, and a front wheel 7 provided at a position below the equipment storage chamber 2 and a rear end of the vehicle body 1 at a position below the loading platform 5. The left and right rear wheels 8 traveled. Here, the front wheel 7 serves as both a driving wheel and a steering wheel, and is arranged at the center in the left-right direction of the vehicle body 1. The rear wheel 8 is a driven wheel, and as shown in FIG.

  Further, the front portion of the vehicle body 1 is provided with a front frame 1A whose upper surface is substantially flush with the upper surface of the cab 3. The front frame 1A is opened up and down as shown in FIG. A cylindrical housing 1B in a plan view is erected, and further, as shown in FIGS. 2 and 3, a bumper 1C in an arc shape in a plan view is provided along the front edge of the front frame 1A. The equipment storage chamber 2 is partitioned by a side cover 2A that is erected and supported by the housing 1B, and a top cover 2B that is provided so as to cover the upper edge of the side cover 2A. As shown in FIG. A motor 12 and the like for driving the front wheel 7 are accommodated in the interior.

  As shown in FIG. 3, a support member 9 is fixed to the upper end portion of the housing 1B, and a drive device 10 that supports the front wheel 7 is provided on the support member 9 so as to be rotatable about a vertical axis. A disk-shaped support base 11 is fixed to the upper part of the drive device 10, and a motor 12 for driving the front wheels 7 and a controller 13 for controlling the motor 12 are installed on the support base 11. As a result, the front wheel 7, the drive device 10, the support base 11, the motor 12, and the controller 13 are integrally turned.

  The support base 11 is provided with a steering angle sensor 11A for detecting a turning state relative to the support member 9 or the housing 1B (or the vehicle body 1), that is, a steering angle of the front wheel 7, and the steering angle sensor 11A is As shown in FIG. 4, the steering angle θ is detected as a positive value in the clockwise direction in the plan view and a negative value in the counterclockwise direction when the front wheel 7 is in the straight traveling state in the forward direction, and the detection result is sent to the controller 13. Entered. Further, the motor 12 is provided with a rotation sensor 12A comprising an encoder, and the detection result, that is, the motor rotation speed is input to the controller 13.

  As shown in FIGS. 1 to 3, the device storage chamber 2 is provided with a steering handle 14 for steering the front wheels 7. This steering handle 14 is formed in an annular shape and is arranged slightly above the top cover 2B, a spoke 14B having one end connected to the wheel 14A, and the other end of the spoke 14B connected to the spoke 14B. Via a disc-shaped base 14C for supporting the wheel 14A, a shaft 14D extending downward from the base 14C, and a bracket 14E connected to the lower end of the shaft 14D and fixed to the support base 11 It has become.

  In addition, the top cover 2B inside the wheel 14A has an accelerator device 15 having an operation ring for adjusting the traveling speed, and a directional device 16 having an operation lever for switching the traveling direction between forward and reverse. And are provided. The accelerator device 15 is provided with an accelerator sensor 15A comprising a potentiometer for detecting the operation amount of the operation ring, and the directional device 16 is provided with a forward / reverse switch 16A comprising a micro switch for detecting the position of the operation lever. The detection result is input to the controller 13.

  Further, the driver's cab 3 is provided with a brake pedal 17 and a brake lever 18 for operating a brake device (not shown). The driver operates the brake pedal 17 to reduce the traveling speed, and the brake lever 18 is operated to stop (park) the electric vehicle.

  As shown in FIG. 5, the controller 13 according to the first embodiment includes a travel speed calculation unit 130 that calculates the actual travel speed of the electric vehicle, and a target travel that calculates a target travel speed that causes the electric vehicle to travel. Speed calculation means 131, traveling direction determination means 132 for determining whether the traveling direction is the forward direction or the reverse direction, and whether the steering direction is a direction in which the front wheel 7 is moved away from the straight traveling state or a direction in which the front wheel 7 is brought closer to the straight traveling state. Steering direction determination means 133 for determining and drive control means 134 for controlling the motor 12 so that the actual traveling speed becomes the target traveling speed are provided.

The travel speed calculation means 130 multiplies the number of rotations of the motor 12 from the rotation sensor 12A by a predetermined coefficient to obtain the actual travel speed V, and the target travel speed calculation means 131 calculates the operation amount S from the accelerator sensor 15A and Based on the determination result by the traveling direction determination unit 132, the steering angle θ of the front wheel 7 from the steering angle sensor 11A, and the determination result by the steering direction determination unit 133, the target traveling speed Va is obtained.
Based on the detection result of the forward / reverse switch 16A, the traveling direction determination means 132 determines the traveling direction as the forward direction when the operation lever of the directional device 16 is located at the forward operation position, and the reverse operation position. When the vehicle is in the position, the traveling direction is determined as the reverse direction.
The steering direction determination means 133 calculates the amount of change Δθ per unit time of the steering angle θ using the steering angle θ of the front wheel 7 from the steering angle sensor 11A, and makes a determination based on the steering angle θ and the amount of change Δθ. Do. That is, when the steering angle θ is positive and the change amount Δθ is positive, when the steering angle θ is negative and the change amount Δθ is negative, it is determined that the steering direction is the direction in which the front wheel 7 is moved away from the straight traveling state. When the angle θ is positive and the change amount Δθ is negative, and when the steering angle θ is negative and the change amount Δθ is positive, the steering direction is determined to be a direction in which the front wheels 7 are brought close to a straight traveling state.
The drive control means 134 adjusts the rotational speed of the motor 12 at a predetermined angular acceleration so that the travel speed V calculated by the travel speed calculation means 130 matches the target travel speed Va calculated by the target travel speed calculation means 131. Increase / decrease control is performed, and when the actual traveling speed V matches the target traveling speed Va, the state is maintained in that state.

  Hereinafter, the control of the motor 12 by the controller 13 will be further described with reference to FIGS.

  As shown in FIG. 6, when the accelerator operation amount S is detected (S1) and the motor speed is detected (S2), the controller 13 calculates the traveling speed V (S3), and the traveling direction is the forward direction. It is determined whether or not (S4). When it is determined that the vehicle is in the forward direction, the steering angle θ of the front wheel 7 is detected (S5), and the controller 13 calculates the change amount Δθ (S6). Then, it is determined whether the steering angle θ is greater than 0 or the change amount Δθ is greater than 0 (S7, S8, S9).

  When the steering angle θ is greater than 0 and the change amount Δθ is greater than 0, and when the steering angle θ is not greater than 0 and the change amount Δθ is not greater than 0, the steering direction is such that the steering direction moves the front wheels 7 away from the straight traveling state. It is determined that the steering angle θ is larger than the predetermined angle θ2 as an absolute value (S10). If the steering angle θ is smaller in absolute value, the target travel speed Va is set for the operation amount S as shown in FIG. 8 (S11). If the steering angle θ is larger in absolute value, the target travel speed Va is set for the operation amount S (S12), and the target travel speed Va is corrected and reset with the reduction rate d2 (S13). That is, similarly to S11, the target travel speed Va set in S12 is corrected using the reduction rate d2 set in advance according to the steering angle θ, and the corrected value is reset as the target travel speed Va. .

  When the steering angle θ is greater than 0 and the change amount Δθ is not greater than 0, and when the steering angle θ is not greater than 0 and the change amount Δθ is greater than 0, the steering direction is such that the steering direction brings the front wheel 7 closer to the straight traveling state. It is determined that the steering angle θ is larger than a predetermined angle θ1 (<θ2) as an absolute value (S14). If the steering angle θ is smaller in absolute value, the target travel speed Va is set for the operation amount S as shown in FIG. 8 (S11). If the steering angle θ is larger in absolute value, the target travel speed Va is set for the operation amount S (S15), and the target travel speed Va is corrected and reset with the reduction rate d1 (S16). That is, similarly to S11, the target travel speed Va set in S15 is corrected using the reduction rate d1 set in advance according to the steering angle θ, and the corrected value is reset as the target travel speed Va. .

  When the target travel speed Va is thus set or corrected and set, the controller 13 compares the target travel speed Va with the actual travel speed V that has already been obtained, as shown in FIG. 6 (S17, S18). . When the actual travel speed V is higher than the target travel speed Va, the motor 12 is decelerated (S19), and when the actual travel speed V is lower than the target travel speed Va, the motor 12 is increased (S20). When the actual traveling speed V matches the target traveling speed Va, the rotational speed of the motor 12 is maintained as it is (S21).

  When it is determined in S4 that the vehicle is not in the forward direction, the controller 13 determines whether or not the traveling direction is the backward direction as shown in FIG. 7 (S22), and the steering angle θ of the front wheel 7 is detected. If so (S23), the change amount Δθ is calculated (S24). Then, it is determined whether the steering angle θ is greater than 0 or the change amount Δθ is greater than 0 (S25, S26, S27).

  When the steering angle θ is greater than 0 and the change amount Δθ is greater than 0, and when the steering angle θ is not greater than 0 and the change amount Δθ is not greater than 0, the steering direction is such that the steering direction moves the front wheels 7 away from the straight traveling state. It is determined that the steering angle θ is greater than a predetermined angle θ4 (<θ2) as an absolute value (S28). Here, if the steering angle θ is smaller in absolute value, the target travel speed Va is set for the operation amount S as shown in FIG. 8 (S29). If the steering angle θ is larger in absolute value, the target travel speed Va is set for the operation amount S (S30), and the target travel speed Va is corrected and reset with the reduction rate d4 (S31). That is, similarly to S29, the target travel speed Va set in S30 is corrected using a reduction rate d4 set in advance according to the steering angle θ, and the corrected value is reset as the target travel speed Va. .

  When the steering angle θ is greater than 0 and the change amount Δθ is not greater than 0, and when the steering angle θ is not greater than 0 and the change amount Δθ is greater than 0, the steering direction is such that the steering direction brings the front wheel 7 closer to the straight traveling state. It is determined that the steering angle θ is larger than a predetermined angle θ3 (<θ4) as an absolute value (S32). Here, if the steering angle θ is smaller in absolute value, the target travel speed Va is set for the operation amount S as shown in FIG. 8 (S29). If the steering angle θ is larger in absolute value, the target travel speed Va is set for the operation amount S (S33), and the target travel speed Va is corrected and reset with the reduction rate d3 (S34). That is, similarly to S29, the target travel speed Va set in S33 is corrected using a reduction rate d3 set in advance according to the steering angle θ, and the corrected value is reset as the target travel speed Va. .

  When the target travel speed Va is thus set or corrected and set, the controller 13 compares the target travel speed Va with the actual travel speed V that has already been obtained, as shown in FIG. 7 (S35, S36). . When the actual travel speed V is higher than the target travel speed Va, the motor 12 is decelerated (S37), and when the actual travel speed V is lower than the target travel speed Va, the motor 12 is increased (S38). When the actual travel speed V matches the target travel speed Va, the rotational speed of the motor 12 is maintained as it is (S39).

  Note that when the traveling direction is neither the forward direction nor the reverse direction, that is, when the operating lever of the directional device 16 is not operated to the forward side or the reverse side, the controller 13 performs the motor 12 regardless of the operation of the accelerator device 15. Is stopped (S40).

FIG. 9 shows the relationship between the steering angle θ and the target travel speed Va when the travel direction is the forward direction and the operation amount S of the operation ring of the accelerator device 15 is the maximum (operation amount Smax). As shown in FIG. 9, when the front wheel 7 is steered away from the straight traveling state (steering angle θ = 0) during forward travel, the target travel speed Va is within the range of the steering angle θ of −θ1 ≦ θ ≦ θ1. Although the speed Vmax corresponds to the operation amount Smax, when the steering angle θ exceeds the above range, the speed is reduced from the speed Vmax, and when the steering angle θ reaches a limit value (θmax, −θmax), the target The traveling speed Va is a speed V1. The speed V1 at this time is
V1 = Vmax− | θmax−θ1 | × Vmax × d1
It is represented by Further, when the front wheel 7 is steered in a direction to approach the straight traveling state (steering angle θ = 0) during forward travel, the target travel speed Va corresponds to the operation amount Smax when the steering angle θ is in the range of −θ2 ≦ θ ≦ θ2. When the steering angle θ exceeds the above range, the speed is reduced to a speed lower than the speed Vmax. When the steering angle θ reaches a limit value (θmax, −θmax), the target travel speed Va is the speed V1. It is said. That is, the speed V1 is
V1 = Vmax− | θmax−θ2 | × Vmax × d2
It can also be expressed as

On the other hand, FIG. 10 shows the relationship between the steering angle θ and the target travel speed Va when the travel direction is the reverse direction and the operation amount S of the operation ring of the accelerator device 15 is the maximum (operation amount Smax). As shown in FIG. 10, when the front wheel 7 is steered in a direction away from the straight traveling state (steering angle θ = 0) during reverse travel, the target travel speed Va is within the range of the steering angle θ of −θ3 ≦ θ ≦ θ3. Although the speed Vmax corresponds to the operation amount Smax, when the steering angle θ exceeds the above range, the speed is reduced from the speed Vmax, and when the steering angle θ reaches a limit value (θmax, −θmax), the target The traveling speed Va is a speed V2 (<V1). The speed V2 at this time is
V2 = Vmax− | θmax−θ3 | × Vmax × d3
It is represented by Further, when the front wheel 7 is steered in the direction of approaching the straight traveling state (steering angle θ = 0) during reverse travel, the target travel speed Va corresponds to the operation amount Smax when the steering angle θ is in the range of −θ4 ≦ θ ≦ θ4. When the steering angle θ exceeds the above range, the speed is reduced to a speed lower than the speed Vmax. When the steering angle θ reaches a limit value (θmax, −θmax), the target travel speed Va is the speed V2. It is said. That is, the speed V2 is
V2 = Vmax− | θmax−θ4 | × Vmax × d4
It can also be expressed as

According to the first embodiment, when the front wheel 7 is steered in a direction away from the straight traveling state, the traveling speed is controlled from a relatively small steered state based on the straight traveling state. The transport vehicle can run stably.
On the other hand, when the front wheel 7 is steered in a direction approaching the straight traveling state, control is performed to suppress the traveling speed when the front wheel 7 is steered relatively large with reference to the straight traveling state, but the traveling speed is reduced when the steering is small. Since it is not suppressed, the vehicle can travel at a high speed as necessary, and the driver can travel without feeling stress or reducing the efficiency related to the transportation work.

  Further, since the angle range in which the traveling speed is not suppressed at the time of reverse traveling with a higher degree of danger is narrowed, the traveling speed is suppressed from a relatively small steering angle θ, thereby improving the safety of the vehicle. . On the other hand, since the degree of danger is lower when traveling forward than when traveling backward, the angular range in which traveling speed is not suppressed is widened, so that traveling speed can be prevented from being suppressed more than necessary while ensuring safety. .

  In the first embodiment described above, the traveling speed is suppressed to realize stable traveling of the electric vehicle, but instead of this, stable traveling can also be realized by suppressing traveling acceleration. Therefore, an example (Example 2) in which the traveling acceleration is suppressed will be described below. The description of the same configuration as that of the first embodiment is omitted.

  As shown in FIG. 11, the controller 13 according to the second embodiment includes a travel speed calculation means 130 that calculates the actual travel speed of the electric vehicle, and a target travel that calculates a target travel speed that causes the electric vehicle to travel. Speed calculation means 131, traveling direction determination means 132 for determining whether the traveling direction is the forward direction or the reverse direction, and whether the steering direction is a direction in which the front wheel 7 is moved away from the straight traveling state or a direction in which the front wheel 7 is brought closer to the straight traveling state. Steering direction determination means 133 for determining and drive control means 134 for controlling the motor 12 so that the actual traveling speed becomes the target traveling speed are provided.

The traveling speed calculation means 130 obtains the traveling speed V by multiplying the number of rotations of the motor 12 from the rotation sensor 12A by a predetermined coefficient, and the target traveling speed calculation means 131 is based on the operation amount S from the accelerator sensor 15A. A target travel speed Va is obtained.
Based on the detection result of the forward / reverse switch 16A, the traveling direction determination means 132 determines the traveling direction as the forward direction when the operation lever of the directional device 16 is located at the forward operation position, and the reverse operation position. When the vehicle is in the position, the traveling direction is determined as the reverse direction.
The steering direction determination means 133 calculates the amount of change Δθ per unit time of the steering angle θ using the steering angle θ of the front wheel 7 from the steering angle sensor 11A, and makes a determination based on the steering angle θ and the amount of change Δθ. Do. That is, when the steering angle θ is positive and the change amount Δθ is positive, when the steering angle θ is negative and the change amount Δθ is negative, it is determined that the steering direction is the direction in which the front wheel 7 is moved away from the straight traveling state. When the angle θ is positive and the change amount Δθ is negative, and when the steering angle θ is negative and the change amount Δθ is positive, the steering direction is determined to be a direction in which the front wheels 7 are brought close to a straight traveling state.
The drive control means 134 controls increase / decrease of the rotation speed of the motor 12 so that the travel speed V calculated by the travel speed calculation means 130 and the target travel speed Va calculated by the target travel speed calculation means 131 coincide with each other. When the actual traveling speed V matches the target traveling speed Va, the state is maintained in that state. Here, the drive control unit 134 sets the traveling acceleration A based on the determination result of the traveling direction determination unit 132, the steering angle θ of the front wheel 7 from the steering angle sensor 11A, and the determination result of the steering direction determination unit 133. Then, the rotational speed of the motor 12 is controlled so that the traveling speed V increases or decreases with the traveling acceleration A.

  Hereinafter, control of the motor 12 by the controller 13 will be further described with reference to FIG. 8 and FIGS. 12 to 15.

  As shown in FIG. 12, when the accelerator operation amount S is detected (S1), the controller 13 calculates the target travel speed Va as shown in FIG. 8 (S2), and when the motor rotation speed is detected (S2). S3) The controller 13 calculates the traveling speed V (S4), and determines whether or not the traveling direction is the forward direction (S5). When it is determined that the vehicle is in the forward direction, the steering angle θ of the front wheel 7 is detected (S6), and the controller 13 calculates the change amount Δθ (S7). Then, it is determined whether the steering angle θ is greater than 0 or the change amount Δθ is greater than 0 (S8, S9, S10).

  When the steering angle θ is greater than 0 and the change amount Δθ is greater than 0, and when the steering angle θ is not greater than 0 and the change amount Δθ is not greater than 0, the steering direction is such that the steering direction moves the front wheels 7 away from the straight traveling state. It is determined that the steering angle θ is larger than the predetermined angle θ2 as an absolute value (S11). If the steering angle θ is smaller as an absolute value, the traveling acceleration A is set (S12). If the steering angle θ is larger in absolute value, the traveling acceleration A is set (S13), and the traveling acceleration A is corrected and reset by the reduction rate d2 (S14). That is, the travel acceleration A set in S13 is corrected using a reduction rate d2 set in advance according to the steering angle θ, and the corrected value is reset as the travel acceleration A.

  When the steering angle θ is greater than 0 and the change amount Δθ is not greater than 0, and when the steering angle θ is not greater than 0 and the change amount Δθ is greater than 0, the steering direction is such that the steering direction brings the front wheel 7 closer to the straight traveling state. It is determined that the steering angle θ is larger than a predetermined angle θ1 (<θ2) as an absolute value (S15). If the steering angle θ is smaller as an absolute value, the traveling acceleration A is set (S12). If the steering angle θ is larger in absolute value, the traveling acceleration A is set (S16), and the traveling acceleration A is corrected and reset with the reduction rate d1 (S17). That is, the travel acceleration A set in S16 is corrected using a reduction rate d1 set in advance according to the steering angle θ, and the corrected value is reset as the travel acceleration A.

  When the travel acceleration A is set or corrected, the controller 13 compares the target travel speed Va with the actual travel speed V as shown in FIG. 12 (S18, S19). When the actual travel speed V is higher than the target travel speed Va, the motor 12 is decelerated (S20). When the actual travel speed V is lower than the target travel speed Va, the motor 12 is increased (S21). When the actual traveling speed V matches the target traveling speed Va, the rotational speed of the motor 12 is maintained as it is (S22).

  When it is determined in S5 that the vehicle is not in the forward direction, the controller 13 determines whether or not the traveling direction is the backward direction as shown in FIG. 13 (S23), and the steering angle θ of the front wheels 7 is determined. If detected (S24), the change amount Δθ is calculated (S25). Then, it is determined whether the steering angle θ is greater than 0 or the change amount Δθ is greater than 0 (S26, S27, S28).

  When the steering angle θ is greater than 0 and the change amount Δθ is greater than 0, and when the steering angle θ is not greater than 0 and the change amount Δθ is not greater than 0, the steering direction is such that the steering direction moves the front wheels 7 away from the straight traveling state. It is determined that the steering angle θ is larger than a predetermined angle θ4 (<θ2) as an absolute value (S29). Here, if the steering angle θ is smaller in absolute value, the traveling acceleration A is set (S30). If the steering angle θ is larger in absolute value, the traveling acceleration A is set (S31), and the traveling acceleration A is corrected and reset at the reduction rate d4 (S32). That is, the travel acceleration A set in S31 is corrected using a reduction rate d4 set in advance according to the steering angle θ, and the corrected value is reset as the travel acceleration A.

  When the steering angle θ is greater than 0 and the change amount Δθ is not greater than 0, and when the steering angle θ is not greater than 0 and the change amount Δθ is greater than 0, the steering direction is such that the steering direction brings the front wheel 7 closer to the straight traveling state. It is determined that the steering angle θ is greater than a predetermined angle θ3 (<θ4) as an absolute value (S33). Here, if the steering angle θ is smaller in absolute value, the traveling acceleration A is set (S30). If the steering angle θ is larger in absolute value, the traveling acceleration A is set (S34), and the traveling acceleration A is corrected and reset at the reduction rate d3 (S35). That is, the travel acceleration A set in S34 is corrected using a reduction rate d3 set in advance according to the steering angle θ, and the corrected value is reset as the travel acceleration A.

  When the traveling acceleration A is set or corrected and set in this way, the controller 13 compares the target traveling speed Va with the actual traveling speed V as shown in FIG. 13 (S36, S37). When the actual travel speed V is higher than the target travel speed Va, the motor 12 is decelerated (S38). When the actual travel speed V is lower than the target travel speed Va, the motor 12 is increased (S39). . When the actual traveling speed V matches the target traveling speed Va, the rotational speed of the motor 12 is maintained as it is (S40).

  Note that when the traveling direction is neither the forward direction nor the reverse direction, that is, when the operating lever of the directional device 16 is not operated to the forward side or the reverse side, the controller 13 performs the motor 12 regardless of the operation of the accelerator device 15. Is stopped (S41).

FIG. 14 shows the relationship between the steering angle θ and the traveling acceleration A when the traveling direction is the forward direction. As shown in FIG. 14, when the front wheel 7 is steered in the direction away from the straight traveling state (steering angle θ = 0) during forward travel, the traveling acceleration A is maximum when the steering angle θ is in the range of −θ1 ≦ θ ≦ θ1. When the steering angle θ exceeds the above range, the acceleration is reduced from the acceleration Amax. When the steering angle θ reaches a limit value (θmax, −θmax), the traveling acceleration A is an acceleration. A1. The speed A1 at this time is
A1 = Amax− | θmax−θ1 | × Amax × d1
It is represented by Further, when the front wheel 7 is steered in the direction of approaching the straight traveling state (steering angle θ = 0) during forward travel, the traveling acceleration A becomes the maximum value Amax when the steering angle θ is in the range of −θ2 ≦ θ ≦ θ2. However, when the steering angle θ exceeds the above range, the acceleration is reduced from the acceleration Amax. When the steering angle θ reaches the limit values (θmax, −θmax), the traveling acceleration A is set to the acceleration A1. That is, the acceleration A1 is
A1 = Amax− | θmax−θ2 | × Amax × d2
It can also be expressed as

On the other hand, FIG. 15 shows the relationship between the steering angle θ and the traveling acceleration A when the traveling direction is the reverse direction. As shown in FIG. 15, when the front wheel 7 is steered away from the straight traveling state (steering angle θ = 0) during forward travel, the traveling acceleration A is maximum when the steering angle θ is in the range of −θ3 ≦ θ ≦ θ3. When the steering angle θ exceeds the above range, the acceleration is reduced from the acceleration Amax. When the steering angle θ reaches a limit value (θmax, −θmax), the traveling acceleration A is an acceleration. A2 (<A1). The speed A2 at this time is
A2 = Amax− | θmax−θ3 | × Amax × d3
It is represented by Further, when the front wheel 7 is steered in a direction to approach the straight traveling state (steering angle θ = 0) during forward travel, the traveling acceleration A becomes Amax, which is the maximum value, when the steering angle θ is in the range of −θ4 ≦ θ ≦ θ4. However, when the steering angle θ exceeds the above range, the acceleration is set to be lower than the acceleration Amax. When the steering angle θ reaches the limit values (θmax, −θmax), the traveling acceleration A is set to the acceleration A2. That is, the acceleration A2 is
A2 = Amax− | θmax−θ4 | × Amax × d4
It can also be expressed as

  According to the second embodiment, when the front wheel 7 is steered in a direction away from the straight traveling state, the control for suppressing the travel acceleration is performed from a relatively small steered state based on the straight traveling state. Acceleration / deceleration is prevented, and the electric vehicle can travel stably. On the other hand, when the front wheel 7 is steered in a direction approaching the straight traveling state, control for suppressing travel acceleration is performed in a state where the front wheel 7 is steered relatively large with respect to the straight travel state. Since the vehicle is not restrained, the vehicle can travel without prompt acceleration / deceleration without causing the driver to feel stress or reducing the efficiency of the transportation work.

  In addition, since the angular range in which the travel acceleration is not suppressed during backward travel with a higher degree of danger is narrowed, the travel acceleration is suppressed while the steering angle θ is relatively small, thereby improving the safety of the electric vehicle. Can do. On the other hand, since the degree of danger is lower when traveling forward than when traveling backward, the angle range in which traveling acceleration is not suppressed is widened, so that traveling acceleration can be prevented from being suppressed more than necessary while ensuring safety. .

1 is a side view of an electric transport vehicle according to an embodiment of the present invention. It is a top view of the electric transport vehicle which concerns on the Example of this invention. 1 is a side view of an electric transport vehicle according to an embodiment of the present invention. It is a schematic diagram which concerns on the Example of this invention. It is a functional block diagram of Example 1 of the present invention. It is a control flow figure of Example 1 of the present invention. It is a control flow figure of Example 1 of the present invention. It is a control characteristic figure concerning the example of the present invention. It is a control characteristic figure of Example 1 of the present invention. It is a control characteristic figure of Example 1 of the present invention. It is a functional block diagram of Example 2 of the present invention. It is a control flow figure of Example 2 of the present invention. It is a control flow figure of Example 2 of the present invention. It is a control characteristic figure of Example 2 of the present invention. It is a control characteristic figure of Example 2 of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Car body 2 Equipment storage room 3 Driver's cab 5 Car bed 7 Front wheel 8 Rear wheel 10 Drive apparatus 11 Support base 11A Steering angle sensor 12 Motor 12A Rotation sensor 13 Controller 14 Steering handle 15 Accelerator apparatus 15A Accelerator sensor 16 Directional apparatus 16A Forward / reverse switch

Claims (4)

In a vehicle including a drive wheel that travels and a steering wheel that steers, a travel control device that controls a drive device that travels and drives the drive wheel,
Speed detection means for detecting the traveling speed of the vehicle, steering angle detection means for detecting the steering angle of the steering wheel, steering direction determination means for determining the steering direction of the steering wheel, and the steering angle being the steering wheel Steering angle determination means for determining whether or not a predetermined angle range centered on the angle when the vehicle is in a straight traveling state, angle range changing means for changing the angle range according to the steering direction, and Drive control means for suppressing and controlling the output of the drive device so that the traveling speed is not more than a predetermined value when the steering angle is not within the angle range;
The angle range changing means changes the angle range wider when the steering direction is a direction in which the steered wheel is brought closer to a straight traveling state than when the steering wheel is in a direction away from the straight traveling state. Travel control device. In a vehicle including a drive wheel that travels and a steering wheel that steers, a travel control device that controls a drive device that travels and drives the drive wheel,
Steering angle detecting means for detecting the steering angle of the steered wheel, steering direction determining means for determining the steering direction of the steered wheel, and a predetermined centered on an angle when the steered wheel makes the steered wheel go straight. A steering angle determination means for determining whether or not the angle range is within an angle range; an angle range change means for changing the angle range according to the steering direction; and when the steering angle is not within the angle range, Drive control means for suppressing and controlling the output of the drive device so that the running acceleration of the vehicle is a predetermined value or less,
The angle range changing means changes the angle range wider when the steering direction is a direction in which the steered wheel is brought closer to a straight traveling state than when the steering wheel is in a direction away from the straight traveling state. Travel control device. A forward / reverse determination means for determining whether the traveling direction of the vehicle is a forward direction or a reverse direction;
3. The vehicle travel control device according to claim 1, wherein the angle range changing unit changes the angle range narrower when the traveling direction is a backward direction than when the traveling direction is a forward direction. . The vehicle is provided with a front wheel serving as a driving wheel and a steering wheel and a rear wheel as a driven wheel on the vehicle body, and further provided with a loading platform above the rear wheel, and a driver boarding the front position of the loading platform. A vehicle equipped with a driver's cab,
4. The steering angle detection means detects a steering angle of the front wheel, and the steering direction determination means determines a steering direction of the front wheel. The vehicle travel control device according to claim 1.

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