JP4159435B2 - Auto guidance vehicle - Google Patents

Description

  The present invention relates to an auto guidance vehicle that travels while automatically controlling steering along a guide member laid on a travel path.

  Some auto guidance type vehicles have two driving modes, a manual steering mode and an automatic steering mode. In the manual steering mode, by manually operating the steering wheel, the steering tire turns by an angle corresponding to the steering angle, and the vehicle body turns in a predetermined direction. On the other hand, in the automatic steering mode, the steering wheel is in a free state, and a sensor provided on the vehicle body detects a guide member such as a tape magnet or a guide wire laid on the travel path, and based on this detection output. Thus, the steering is automatically controlled, and the vehicle body travels along the guide member on the travel path.

  In this auto-guidance type vehicle, an accelerator for changing the traveling speed is provided in the driver's seat, as in a normal vehicle. The accelerator is operated by a driver with a lever. The traveling speed increases as the lever is tilted, and the traveling speed decreases when the lever is returned. With respect to the traveling speed, even in the case of the automatic steering mode, automatic control as in the case of steering is not performed. That is, in the automatic steering mode, the automatic control is performed only for the steering, and the driving speed is left to the driver's operation.

As a prior art document disclosing an auto guidance type vehicle, for example, there is Patent Document 1 below. Patent Document 2 discloses a technique related to traveling speed control of an automatic guided vehicle that moves straight and turns according to an induction track laid on a traveling path. In Patent Document 2, the time required for the turning operation is controlled by controlling the traveling speed so that the start period or the end period of the turning operation accompanied by the steering operation travels at a low speed and the intermediate period of the turning operation travels at a high speed. It can be shortened.
JP-A-9-235100 Japanese Patent Application Laid-Open No. 2002-6654

  As described above, since the auto guidance type vehicle travels with the body direction automatically controlled when the automatic steering mode is set, the driver does not need to pay attention to the steering wheel operation. Therefore, it is required to travel at an appropriate speed according to the judgment of the driver. For example, in the case of a forklift that performs loading and unloading operations such as loading and unloading on rack racks in a warehouse, there is no problem even if the traveling speed is increased when traveling outside the place where the rack is installed. When entering between the racks and traveling along the path between the racks, it is necessary to reduce the traveling speed for safety. However, if the driver is distracted and the forklift is started with the accelerator fully open when entering between racks, the car body may collide with the rack, causing damage to the car body or the rack, and in some cases driving. People may be injured. This will be described in more detail with reference to FIGS.

  FIG. 8 is a plan view showing a state in which an auto guidance forklift enters between racks installed in a warehouse. In the figure, 20 is a rack installed in the warehouse, 21 is a passage formed between the racks 20 and 20, 22 is a guide member such as a tape magnet or guide wire laid on the floor of the passage 21, and 30 is a rack. An auto-guidance type vehicle that performs cargo handling operations such as loading and unloading on 20 shelves, in this example, an auto-guidance type forklift (hereinafter simply referred to as “forklift”). The width W of the passage 21 is, for example, 1500 mm.

  The forklift 30 travels from the right to the left in the figure on the floor of the warehouse, and performs a turning operation to enter between the racks 20 and 20 at the A position. At this time, the operation mode of the forklift 30 is the manual steering mode, and the driver operates the handle to turn the vehicle body of the forklift 30 to the right with respect to the traveling direction. When the vehicle body turns and reaches the B position, the driver temporarily stops the forklift 30 and switches the operation mode from the manual steering mode to the automatic steering mode. Thereafter, the forklift 30 is started by tilting the lever of the accelerator. If the vehicle body goes straight at the start, the forklift 30 detects the guide member 22 laid in the passage 21 with a sensor (not shown) as indicated by the solid line at the C position, and based on the detection output of the sensor. Then, the vehicle travels along the passage 21 along the guide member 22 while automatically controlling the steering.

  However, when the forklift 30 is stopped at the position B, as shown in FIG. 9A, if the steering tire 31 is inclined with respect to the straight traveling direction m of the forklift 30 (inclination angle θ1), the forklift 30 is After starting, the vehicle does not go straight, but runs while swinging left and right as shown in FIG. 9B by automatic steering control. Z1 represents the maximum value of the left and right deflection width. The swing width at this time varies depending on the tilt angle of the steering tire 31, and as shown in FIG. 10A, if the tilt angle θ2 is smaller than θ1, the swing width becomes smaller. Z2 represents the maximum value of the left and right runout width, and Z1> Z2.

  In any case, when the vehicle starts to start with the steering tire 31 tilted, the forklift 30 does not go straight, but comes into contact with the rack 20 like the forklift 30 indicated by the broken line at position C in FIG. For this reason, when the accelerator is fully opened and started, the forklift 30 violently collides with the rack 20 at the entrance or inside of the passage 21, which causes a safety problem. In order to avoid this, the width W of the passage 21 may be increased. However, this not only increases the installation space of the rack 20, but also increases the distance between the forklift 30 and the rack 20 and hinders handling work. Arise. No solution is disclosed in Patent Document 1 and Patent Document 2 for the above problems.

  The present invention solves the above-described problems, and an object of the present invention is to provide an auto-guidance type vehicle having improved straight running performance when starting in the automatic steering mode.

The present invention includes a travel motor for traveling a vehicle body, a steering motor for steering a steering tire to change the direction of the vehicle body, a detection means for detecting a guide member laid on a travel path, and the travel motor. A control unit that controls the steering motor based on the accelerator operation by the driver and that automatically controls the steering motor based on the detection output of the detection unit, and that allows the vehicle body to travel while performing automatic steering control. In the vehicle, when the start of the vehicle body is started based on the accelerator operation by the driver , the control unit travels based on the accelerator operation by the driver until a predetermined time has elapsed from the start of the start. control the traveling motor so that the running speed of the vehicle does not exceed a predetermined value be greater indication of speed As well as the steering speed of the steering tire so as to control the steering motor to be larger than the normal steering speed.

  In this way, when the automatic steering mode is set, the traveling speed is limited to a certain level or less even if the accelerator lever is largely tilted until a certain time has elapsed since the start of starting. The distance traveled while the vehicle swings from side to side is shortened. On the other hand, by increasing the steering speed of the steering tire until a certain time has elapsed from the start of starting, the left and right runout width is reduced, and the time until the runout converges is also shortened. Therefore, by limiting the traveling speed and increasing the steering speed, the vehicle shifts to a stable straight traveling state in a short time without causing a large shake immediately after starting. As a result, even when the vehicle enters a narrow space such as a path between racks, the vehicle body is less likely to come into contact with or collide with the vehicle body, and damage to the vehicle body can be avoided and driver safety is ensured.

  In the present invention, the travel distance from the start of start may be used instead of the elapsed time from the start of start described above. In this case, a means for measuring the distance is required, but some vehicles have a distance meter for calculating the mileage. In this case, a distance meter is used as the distance measuring means. Can do.

  According to the present invention, it is possible to improve the straight-ahead performance of the vehicle when the vehicle is started in the automatic steering mode by performing control such as limiting the traveling speed immediately after starting and increasing the steering speed.

  FIG. 1 is an electric block diagram when an auto guidance type vehicle according to an embodiment of the present invention, in particular, an auto guidance type forklift is taken as an example. Here, only the blocks related to the present invention are shown.

  In FIG. 1, reference numeral 1 denotes an operation mode switching switch as a mode switching means, and the operation mode is switched between a manual steering mode and an automatic steering mode by operating this switch. An accelerator 2 for changing the traveling speed is operated by a lever, and the traveling speed of the vehicle body increases as the lever is tilted, and the traveling speed decreases when the lever is returned. Reference numeral 3 denotes a guide sensor as detection means, which is a sensor for detecting the guide member 22 described in FIG. When the guide member 22 is composed of a tape magnet, the guide sensor 3 is composed of a magnetic sensor, and when the guide member 22 is composed of a guide wire, the guide sensor 3 is composed of a pair of pickup coils. In any case, the guide sensor 3 is configured to detect a deviation amount from the guide member 22. 4 is a timer for counting the elapsed time since the forklift started. The timer 4 may be provided in the CPU 11 described later.

  Reference numeral 5 denotes a travel motor drive unit which includes a motor drive circuit for supplying current to the travel motor 6 for traveling the vehicle body. A steering motor driving unit 7 includes a motor driving circuit for supplying current to the steering motor 8 for steering the steering tire to change the direction of the vehicle body. Reference numeral 9 denotes a ROM in which programs and control parameters of the CPU 11 are stored, and reference numeral 10 denotes a RAM in which various data are temporarily stored. Reference numeral 11 denotes a CPU as a control unit that controls the traveling motor 6 and the steering motor 8. In the automatic steering mode, the CPU 11 performs rotation control of the traveling motor 6 and the steering motor 8 based on the count value of the timer 4 to control the traveling speed and the steering speed (the turning speed of the steering tire). Details thereof will be described later.

  Next, the principle of the present invention will be described. In the present invention, when the driving mode changeover switch 1 is set to the automatic steering mode, when the accelerator 2 is operated and the forklift starts to start, until the timer 4 counts a certain time (for example, 3 seconds), The CPU 11 controls the traveling motor drive unit 5 so that the speed of the traveling motor 6 does not exceed a predetermined value (for example, 1 km / h) even if the lever of the accelerator 2 is largely tilted. FIG. 2 is a diagram comparing the traveling status of the forklift 30 when the traveling speed is not limited and when the traveling speed is limited. When the travel speed is not limited, as shown in FIG. 2 (a), the distance L1 traveled while the forklift 30 swings to the left and right becomes longer, but when the travel speed is limited, as shown in FIG. 2 (b), The distance L2 that the forklift 30 travels while swinging left and right is shortened.

  In the present invention, the CPU 11 controls the steering motor drive unit 7 so that the steering speed of the steering tire by the steering motor 8 is higher than the normal steering speed until the timer 4 counts a certain time. For example, if the normal steering speed is 120 deg / sec, the steering speed is increased to about 200 deg / sec. FIG. 3 is a diagram comparing the traveling state of the forklift 30 when the steering speed is not increased and when the steering speed is increased. When the steering speed is not increased, even if automatic steering control is performed, the turning of the steering tire is slow, so that the left and right swing width (maximum value X) of the forklift 30 is large as shown in FIG. The time t1 until the shake converges also becomes longer. On the other hand, when the steering speed is increased, the turning of the steering tire by the automatic steering control becomes steep, so that the left / right deflection width (maximum value Y) of the forklift 30 is reduced and the time until the deflection converges is reduced. t2 is also shortened. Note that when the steering speed is increased, the vehicle body easily shakes, but this can be mitigated by limiting the traveling speed and traveling at a low speed.

  Therefore, the travel state of the forklift 30 is as shown in FIG. 4 by performing both the travel speed limitation and the steering speed increase as described above. That is, even when the steering tire 31 is inclined as shown in FIGS. 9 and 10 at the time of starting, the forklift 30 shifts to a stable straight traveling state in a short time without causing a large shake immediately after starting. As a result, even when the vehicle enters the narrow passage 21 between the racks 20 and 20 as shown in FIG. 8, the body of the forklift 30 is less likely to come into contact with the rack 20 or collide strongly. Can be avoided, and the safety of the driver can be ensured.

  FIG. 5 is a flowchart showing a control procedure of the traveling speed and the steering speed executed by the CPU 11. The operation of the forklift 30 according to the present invention will be described below according to this flowchart.

  When the operation mode changeover switch 1 is switched (step S1), it is determined whether or not the switched mode is the automatic steering mode (step S2). When the mode is not the automatic steering mode (step S2: NO), the manual steering mode is used. Operation is performed (step S11). In the case of the automatic steering mode (step S2: YES), it is next determined whether or not the accelerator 2 has been operated to start a start (step S3). When the start is started (step S3: YES), the timer 4 is started from that point to measure time (step S4). Further, the CPU 11 controls the traveling motor drive unit 5 to limit the traveling speed of the traveling motor 6 so that the speed V of the traveling motor 6 does not exceed a predetermined value Vs even if the lever of the accelerator 2 is largely tilted ( Step S5). Further, the CPU 11 controls the steering motor driving unit 7 to increase the steering speed by the steering motor 8 from the normal V1 to a higher V2 (step S6).

  Thereafter, the count value of the timer 4 is viewed to determine whether or not a predetermined time t has elapsed (step S7). If t seconds have not elapsed (step S7: NO), the process returns to step S5, and the running speed limit in step S5 and the steering speed up state in step S6 are continued. Thereafter, steps S5 to S7 are repeated until t seconds elapse. When t seconds elapse (step S7: YES), the count value of the timer 4 is reset to zero (step S8), the travel speed restriction in step S5 is canceled (step S9), and further in step S6. The increased steering speed V2 is lowered to the original steering speed V1 (step S10). As a result, the forklift 30 is variable in speed up to the maximum value by operating the accelerator 2 and travels under automatic steering control according to the traveling speed operated by the driver.

  FIG. 6 is an electric block diagram of an auto guidance forklift according to another embodiment of the present invention. In the figure, the same parts as those in FIG. In the figure, 1 is an operation mode switching switch for switching the operation mode, 2 is an accelerator for varying the travel speed, 3 is a guide sensor for detecting the guide member 22, 5 is a travel motor drive unit for driving the travel motor 6, 7 Is a steering motor drive unit for driving the steering motor 8, 9 is a ROM for storing a program of the CPU 11, etc., 10 is a RAM for temporarily storing data, 11 is a CPU for controlling the travel motor 6 and the steering motor 8, Is the same as shown in FIG. Reference numeral 12 denotes a distance meter as a distance measuring means for measuring the travel distance of the forklift 30. For example, an encoder that detects the number of rotations of the travel motor 6 and an operation for calculating the travel distance based on an output signal from the encoder. It consists of a circuit part and the like.

  FIG. 7 is a flowchart showing a control procedure of the traveling speed and the steering speed executed by the CPU 11 of FIG. In FIG. 7, the same steps as those in FIG. 5 are denoted by the same reference numerals. Hereinafter, this flowchart will be described. When the operation mode changeover switch 1 is switched (step S1), it is determined whether or not the switched mode is the automatic steering mode (step S2). When the mode is not the automatic steering mode (step S2: NO), the manual steering mode is used. Operation is performed (step S11). In the case of the automatic steering mode (step S2: YES), it is next determined whether or not the accelerator 2 has been operated to start a start (step S3). When the start is started (step S3: YES), the measurement of the travel distance after the start of the start is started based on the travel distance read from the distance meter 12 (step S4a). The travel distance after the start of the start can be calculated, for example, by subtracting the total travel distance from the start of the start to the start of the start. These distance data are stored in a predetermined area of the RAM 10. Further, the CPU 11 controls the traveling motor drive unit 5 to limit the traveling speed of the traveling motor 6 so that the speed V of the traveling motor 6 does not exceed a predetermined value Vs even if the lever of the accelerator 2 is largely tilted ( Step S5). Further, the CPU 11 controls the steering motor driving unit 7 to increase the steering speed by the steering motor 8 from the normal V1 to a higher V2 (step S6).

  Thereafter, referring to the distance data in the RAM 10, it is determined whether or not the forklift 30 has traveled a certain distance (step S7a). If the vehicle has not traveled for a certain distance (step S7a: NO), the process returns to step S5, and the travel speed limit in step S5 and the steering speed up state in step S6 are continued. Thereafter, steps S5 to S7 are repeated until the forklift 30 travels a certain distance. When the vehicle has traveled for a certain distance (step S7a: YES), the travel distance value in the RAM 10 is reset (step S8a), the travel speed restriction in step S5 is canceled (step S9), and the process is increased in step S6. The lowered steering speed V2 is lowered to the original steering speed V1 (step S10). As a result, the forklift 30 is variable in speed up to the maximum value by operating the accelerator 2 and travels under automatic steering control according to the traveling speed operated by the driver.

In the above embodiment, a forklift has been described as an example of an auto-guidance type vehicle. However, the present invention is not limited to this, and other vehicles such as a mere traveling vehicle, a vehicle having only a space for loading a load, and a load are moved. A vehicle or the like equipped with a device (a conveyor, an arm, a slide fork, etc.) for making it possible . Further, in the above-described embodiment, the auto guidance type vehicle is provided with the operation mode changeover switch, and when in the automatic steering mode, until a certain time elapses from the start of starting or until the distance measuring means measures a certain distance from the start of starting. In this example, the travel motor is controlled so that the travel speed does not exceed a predetermined value, and the steering motor is controlled so that the steering speed of the steering tire is larger than the normal steering speed. The present invention can also be applied to a vehicle having no switch.

It is an electric block diagram of the auto guidance type forklift which concerns on embodiment of this invention. It is the figure which compared the traveling condition of the forklift in the case where it restrict | limits when the travel speed is not restrict | limited. It is the figure which compared the traveling condition of the forklift when not increasing the steering speed and when increasing. It is a figure explaining the traveling state of the forklift by this invention. It is the flowchart which showed the control procedure of driving speed and steering speed. It is an electric block diagram of the auto guidance type forklift which concerns on other embodiment of this invention. It is the flowchart which showed the control procedure of the running speed and steering speed in other embodiment. It is the top view which showed a mode that the forklift approached between the racks in a warehouse. It is a figure explaining the running state of a forklift when the inclination-angle of a steering tire is large. It is a figure explaining the running state of a forklift when the inclination-angle of a steering tire is small.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Operation mode changeover switch 2 Accelerator 3 Guide sensor 4 Timer 5 Traveling motor drive part 6 Traveling motor 7 Steering motor drive part 8 Steering motor 9 ROM
10 RAM
11 CPU
12 Distance meter 20 Rack 21 Passage 22 Guide member 30 Forklift 31 Steering tire

Claims (2)

A travel motor for traveling the vehicle body, a steering motor for steering the steering tire to change the direction of the vehicle body, detection means for detecting a guide member laid on the travel path, and an accelerator by the driver by the driver And an automatic guidance type vehicle that travels the vehicle body while performing automatic steering control , and a control unit that automatically controls the steering motor based on the detection output of the detection means .
When the vehicle starts to be started based on an accelerator operation by the driver , the control unit indicates a traveling speed instruction based on the accelerator operation by the driver until a predetermined time has elapsed from the start of the start. The traveling motor is controlled so that the traveling speed of the vehicle body does not exceed a predetermined value even when the vehicle speed is large, and the steering motor is controlled so that the steering speed of the steering tire is larger than a normal steering speed. Auto guidance type vehicle. A travel motor for traveling the vehicle body, a steering motor for steering the steering tire to change the direction of the vehicle body, a detection means for detecting a guide member laid on the travel path, and a distance measurement means for measuring the travel distance And a control unit that controls the travel motor based on an accelerator operation by a driver and automatically controls the steering motor based on a detection output of the detection means, and performs automatic steering control In the auto guidance type vehicle that runs
Wherein, when the starting of the vehicle body on the basis of the driver's operation of the accelerator by is started, from the start initiation to said distance measuring means measures a predetermined distance, the operation of the accelerator by the driver The travel motor is controlled so that the travel speed of the vehicle body does not exceed a predetermined value even when the travel speed instruction is large, and the steering motor is controlled so that the steering speed of the steering tire is higher than the normal steering speed. An auto guidance type vehicle characterized by being controlled.

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