Conveyance vehicle

Abstract

To provide a conveyance vehicle capable of improving runnability in a narrow place.SOLUTION: A conveyance vehicle 1 includes: a protection area setting part 11 which sets a protection area around the vehicle body; a calculation part 12 which calculates speed of the vehicle body; a stop control part 14 which stops the vehicle body when an object is detected within the protection area; and a switching control part 15 which switches width of the protection area extending from a periphery of the vehicle body according to at least speed of the vehicle body.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to an autonomously driven guided vehicle. [Background technology]

[0002] Patent Document 1 below discloses an automatic guided vehicle (AGV) that travels autonomously on a floor surface. This automatic guided vehicle has laser scanners arranged on the front, back, left and right sides, and each laser scanner provides a rectangular sensing area on the front, back, left and right sides of the automatic guided vehicle. Each sensing area includes a protection area provided on the inside of the area and a warning area provided on the outside of the protection area. When a worker enters the warning area, the automatic guided vehicle decelerates, and when the worker enters the protection area, the automatic guided vehicle stops. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7137609 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, when providing protection areas on the front, rear, left and right sides of an automated guided vehicle, it is necessary to secure a passageway wider than the combined width of the protection areas provided on both sides of the vehicle body and the width of the vehicle body itself. However, there are narrow places where such a width cannot be secured, and when an automated guided vehicle travels through such narrow places, an object is detected within the protection area, causing the automated guided vehicle to stop.

[0005] SUMMARY OF THE PRESENT EMBODIMENTS In view of the above, an object of the present invention is to provide a transport vehicle that can improve drivability in narrow spaces. [Means for solving the problem]

[0006] A transport vehicle according to one embodiment of the present invention comprises a protection area setting unit that sets a protection area around the vehicle body, a calculation unit that calculates the speed of the vehicle body, a stop control unit that stops the vehicle body if an object is detected within the protection area, and a switching control unit that switches the width by which the protection area extends from the periphery of the vehicle body based on at least the speed of the vehicle body.

[0007] According to this aspect, the width of the protection area around the vehicle body can be changed based on the speed of the vehicle body, and the vehicle body can be stopped when an object is detected within the range of the protection area. This makes it possible to reduce the width of the protection area by slowing down the vehicle body when traveling in a narrow place, for example.

[0008] In the above aspect, the width of the protection area may be set to a length that ensures a distance that allows the vehicle body to stop without colliding with an object when an object is detected within the protection area.

[0009] According to this aspect, when an object is detected within the protection area, it is possible to reliably stop the vehicle body without colliding with the object.

[0010] In the above aspect, the protection area may be provided within a scanning range of a sensor that measures the distance to an object that may be present around the vehicle body.

[0011] According to this aspect, it is possible to reliably detect objects within the protection area by using the measurement results of a sensor having a scanning range wider than the protection area.

[0012] In the above aspect, the vehicle may further include a detection unit that detects the presence of an object within the protection area based on the distance to the object measured by the sensor.

[0013] According to this aspect, it is possible to detect the presence of an object within the protection area based on the distance to the object measured by the sensor.

[0014] In the above aspect, the vehicle may further include a plurality of motors included in the vehicle body's movement mechanism and a plurality of encoders each detecting an operating status of the motor, and the calculation unit may calculate the vehicle body speed based on an output value of the encoder.

[0015] According to this aspect, it is possible to switch the width of the protection area based on the speed calculated based on the operating status of the motor included in the movement mechanism of the car body. Effect of the Invention

[0016] According to the present invention, a transport vehicle capable of improving drivability in narrow spaces can be provided. [Brief description of the drawings]

[0017] [Figure 1] 1 is a schematic diagram of a transport vehicle according to an embodiment, viewed from directly above; [Diagram 2] FIG. 1 is a schematic diagram showing a transport vehicle provided with a virtual bumper as viewed from directly above. [Diagram 3] FIG. 1 is a schematic diagram showing a transport vehicle provided with a virtual bumper as viewed from directly above. [Figure 4] FIG. 2 is a block diagram illustrating a physical configuration of a transportation vehicle. [Diagram 5] FIG. 2 is a block diagram illustrating a functional configuration of a transportation vehicle. [Figure 6] 4 is a schematic diagram illustrating various conditions for calculating the speed of a vehicle body. FIG. [Figure 7] 10 is a flowchart for explaining an example of an operation of a transportation vehicle according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described with reference to the accompanying drawings, in which like reference numerals denote like or similar configurations.

[0019] 1 is a schematic diagram of a transport vehicle 1 according to an embodiment, viewed from directly above. The transport vehicle 1 is an autonomously travelling device, and may be, for example, a transport platform vehicle that transports luggage or the like placed on the vehicle body, or a transport robot that transports luggage or the like. In this embodiment, a case where the transport vehicle 1 is a transport platform vehicle will be described as an example. The transport vehicle 1 can move in all directions 360 degrees automatically or manually.

[0020] The transport vehicle 1 is equipped with two sensors 2a and 2b. The sensors 2a and 2b are sensors that measure the distance to an object, and are, for example, a laser scanner, a Time Of Flight (TOF) sensor, a Light Detection and Ranging (LiDAR) sensor, etc. In this embodiment, a case will be described in which the sensors 2a and 2b are laser scanners that can scan a range of 270 degrees with laser light.

[0021] The scanning range Ra of the sensor 2a and the scanning range Rb of the sensor 2b partially overlap each other, and by combining the two scanning ranges, it is possible to scan the entire periphery of the transport vehicle 1. This makes it possible to detect objects that may be present around the transport vehicle 1 (in all directions).

[0022] The number of sensors mounted on the transport vehicle 1 is not limited to two, and may be one, or three or more. It is sufficient that the mounted sensor can detect objects present in all directions in which the transport vehicle 1 can move. Objects include, for example, passage walls, shelves and pipes arranged in the passage, other transport vehicles and people present in the passage, etc.

[0023] As shown in FIG. 2, the transport vehicle 1 is provided with a virtual bumper B around the vehicle body. The virtual bumper B is a virtual area formed within the scanning ranges Ra, Rb of the two sensors 2a, 2b, and is a protective area to prevent collision with objects. When an object is detected within the range of the virtual bumper B, the transport vehicle 1 stops. In other words, when an object detected by the sensors 2a, 2b is present within the range of the virtual bumper B, the transport vehicle 1 stops. By forming the virtual bumper B within the scanning ranges Ra, Rb of the sensors 2a, 2b, an object present within the range of the virtual bumper B can be detected using the measurement results of the sensors 2a, 2b.

[0024] It is preferable that the width Wa by which the virtual bumper B projects from the periphery of the vehicle body (hereinafter also referred to as the "virtual bumper width") is set to a length that ensures a distance that allows the vehicle body to stop without colliding with an object detected within the range of the virtual bumper B. This makes it possible to reliably stop the vehicle body without colliding with an object detected within the range of the virtual bumper B.

[0025] The transfer vehicle 1 switches the width of the virtual bumper B based on the speed of the vehicle body. Specifically, when the speed of the vehicle body is less than a predetermined speed, the width of the virtual bumper B is set to a first width Wa shown in Fig. 2. On the other hand, when the speed of the vehicle body becomes equal to or greater than the predetermined speed, the width of the virtual bumper B is switched to a second width Wb shown in Fig. 3. The second width Wb is set to a value (length) larger than the first width Wa.

[0026] The width to be switched based on the speed is not limited to two steps, and may be three or more steps. It is preferable to appropriately set a combination of the speed of the vehicle body and the width of the virtual bumper B to control the switching so that the traveling vehicle body can stop without colliding with a detected object.

[0027] Moreover, the condition for switching the width of the virtual bumper B is not limited to the speed of the vehicle body. For example, the width of the virtual bumper B may be switched based on the weight of the luggage being transported in addition to the speed of the vehicle body. This makes it possible to control the stopping distance of the vehicle body while further considering that the stopping distance varies depending on the weight. In this case, it is preferable to appropriately set a combination of the speed and weight of the vehicle body and the width of the virtual bumper B and control the switching so that the vehicle body traveling with luggage can stop without colliding with a detected object.

[0028] The physical configuration of the transport vehicle 1 will be described with reference to Fig. 4. As shown in the figure, the transport vehicle 1 includes, as its physical configuration, for example, two sensors 2a and 2b, a PLC (Programmable Logic Controller) 3, a servo driver 4, and four servo motors 5a, 5b, 5c, and 5d.

[0029] Each of the sensors 2a and 2b is a distance measuring sensor that measures the distance to an object existing around the transport vehicle 1. The PLC 3 is a control device that controls each part of the transport vehicle 1. The number of PLCs 3 is not limited to one, and multiple PLCs 3 may be provided depending on their roles. The servo driver 4 supplies a drive voltage to the motor so that the motor follows a target value such as a speed command output from a controller such as the PLC 3, and controls the position, speed, output torque, etc. of the motor.

[0030] Each of the servo motors 5a, 5b, 5c, and 5d includes a motor that drives a wheel and an encoder that detects the operation status of the motor. The wheel is a wheel that can move in all directions, and for example, an omni wheel can be used. The encoder feeds back the detected operation status of the motor to the servo driver 4.

[0031] The functional configuration of the transport vehicle 1 will be described with reference to Fig. 5. As shown in the figure, the transport vehicle 1 includes, as its functional configuration, for example, a protection area setting unit 11, a calculation unit 12, a detection unit 13, a stop control unit 14, and a switching control unit 15.

[0032] The protection area setting unit 11 provides a virtual bumper B around the vehicle body in accordance with, for example, an operational instruction from an operator. The virtual bumper B is a virtual area, and has a function of stopping the vehicle body when an object is detected within this area.

[0033] The calculation unit 12 calculates the speed of the vehicle body based on the output values ​​of the encoders included in the servo motors 5a, 5b, 5c, and 5d. This will be specifically described with reference to FIG.

[0034] 6 is a schematic diagram of a transport vehicle 1 equipped with four wheels 6a, 6b, 6c, and 6d. The wheels 6a, 6b, 6c, and 6d and the servo motors 5a, 5b, 5c, and 5d constitute a movement mechanism of the transport vehicle 1.

[0035] Here, the speed of wheel 6a is V1 [m / s], the speed of wheel 6b is V2 [m / s], the speed of wheel 6c is V3 [m / s], and the speed of wheel 6d is V4 [m / s].

[0036] Also, the speed of the carrier 1 in the x direction is V x [m / s], and the speed of the carrier 1 in the y direction is V y [m / s], and the rotational speed of the carrier 1 is Vθ [rad / s].

[0037] Furthermore, the diameter of each of the wheels 6a, 6b, 6c, and 6d is defined as D [m], and the distance from the center O of the vehicle body to each of the wheels 6a, 6b, 6c, and 6d is defined as d [m].

[0038] In this example, the change in the encoder output value per 20 [ms] is Et [rpm], and the change Et is updated every 20 [ms]. Also, the encoder output value until each wheel 6a, 6b, 6c, and 6d rotates once is Er [rpm].

[0039] Under the above conditions, the calculation unit 12 calculates the rotation speed R of each of the wheels 6a, 6b, 6c, and 6d. n (n: 1 to 4) [rpm] is calculated using the following formula (1).

[0040] R n =(Et / Er) × (60000 / 20) … (1) Next, the calculation unit 12 calculates the speeds V of the wheels 6a, 6b, 6c, and 6d. n (n: 1 to 4) [m / s] is calculated by the following formula (2), where π in formula (2) is the circular constant, and Gp is ​​the gear ratio of the reducer.

[0041] V n =(π / 60)×(D / Gp)×R n … (2) Next, the calculation unit 12 calculates the velocity V of the transport vehicle 1 in the x direction. x [m / s], the speed of vehicle 1 in the y direction V y The rotational speed Vθ [rad / s] of the transport vehicle 1 is calculated using the following equation (3).

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[0042] The velocity V of the carrier 1 in the x direction calculated using the above formula (3) x [m / s] and the y-direction velocity V of carrier 1 y [m / s] is substituted into the following formula (4) to calculate the absolute value V [m / s] of the speed of the transport vehicle 1. This absolute value V [m / s] of the speed of the transport vehicle 1 becomes the speed of the vehicle body.

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[0043] Returning to the explanation of Fig. 5, the detection unit 13 detects that an object is present within the virtual bumper B based on the distance to the object measured by the sensors 2a and 2b.

[0044] Specifically, when the distance to the object falls within the range of virtual bumper B, detection unit 13 detects that the object is present within virtual bumper B. On the other hand, when the distance to the object exceeds the range of virtual bumper B, detection unit 13 does not detect that the object is present within virtual bumper B.

[0045] When the detection unit 13 detects an object within the virtual bumper B, the stop control unit 14 stops driving the motor to stop the vehicle body.

[0046] The switching control unit 15 switches the width of the virtual bumper B based on the speed of the vehicle body calculated by the calculation unit 12. In this embodiment, the width of the virtual bumper B is switched to either the first width Wa shown in Fig. 2 or the second width Wb shown in Fig. 3 based on the speed of the vehicle body.

[0047] Specifically, when the speed of the vehicle body is less than a predetermined speed, the switching control unit 15 sets the width of the virtual bumper B to the first width Wa. After that, when the speed of the vehicle body increases to or exceeds the predetermined speed, the switching control unit 15 switches the width of the virtual bumper B from the first width Wa to the second width Wb, and when the speed of the vehicle body decreases to less than the predetermined speed, the switching control unit 15 switches the width of the virtual bumper B from the second width Wb to the first width Wa.

[0048] Next, an example of the operation of the transport vehicle 1 according to the embodiment will be described with reference to FIG.

[0049] First, the protection area setting unit 11 of the transportation vehicle 1 sets up a virtual bumper B having a first width Wa around the vehicle body (step S101).

[0050] Next, the detection unit 13 of the transport vehicle 1 judges whether or not an object is detected within the virtual bumper B (step S102). If the judgment is YES (step S102; YES), the stop control unit 14 of the transport vehicle 1 stops driving the motor and stops the vehicle body (step S103). Then, this operation ends.

[0051] If it is determined in step S102 that no object is detected within virtual bumper B (step S102; NO), the calculation unit 12 of the transport vehicle 1 calculates the speed of the vehicle body based on the output values ​​of the encoders included in the servo motors 5a, 5b, 5c, and 5d (step S104).

[0052] Next, the switching control unit 15 of the transport vehicle 1 judges whether the vehicle body speed calculated in the above step S104 is equal to or greater than a predetermined speed (step S105). If this judgment is YES (step S105; YES), the switching control unit 15 of the transport vehicle 1 switches the width of the virtual bumper B to the second width Wb (step S106) and returns to the processing of the above step S102.

[0053] If it is determined in step S105 that the vehicle speed is not greater than or equal to a predetermined speed (step S105; NO), the switching control unit 15 of the transport vehicle 1 switches the width of the virtual bumper B to the first width Wa (step S107) and returns to the processing of step S102.

[0054] As described above, according to the transport vehicle 1 in the embodiment, the width of the virtual bumper B provided around the vehicle body can be switched based on the speed of the vehicle body, and the vehicle body can be stopped when an object is detected within the range of the virtual bumper B. This makes it possible to reduce the width of the protection area by slowing down the vehicle body speed when traveling in a narrow place, for example.

[0055] Therefore, according to the transport vehicle 1 of the embodiment, it is possible to improve the drivability in narrow places.

[0056] The above-described embodiment is intended to facilitate understanding of the present invention, and is not intended to limit the present invention. The elements of the embodiment, as well as their arrangement, shape, and size, are not limited to those shown in the examples, and can be changed as appropriate. Furthermore, the order of the above-described processing steps can be arbitrarily changed or executed in parallel as long as no inconsistency occurs in the processing content. [Explanation of symbols]

[0057] 1...transport vehicle, 2a, 2b...sensor, 3...PLC, 4...servo driver, 5a, 5b, 5c, 5d...servo motor, 6a, 6b, 6c, 6d...wheel, 11...protection area setting unit, 12...calculation unit, 13...detection unit, 14...stop control unit, 15...switching control unit, B...virtual bumper, Ra, Rb...scanning range, Wa, Wb...width of virtual bumper

Claims

1. a protection area setting unit that sets a protection area around the vehicle body; A calculation unit that calculates a speed of the vehicle body; a stop control unit that stops the vehicle body when an object is detected within the protection area; A switching control unit that switches a width by which the protection area extends from a periphery of the vehicle body based on at least a speed of the vehicle body; A transport vehicle equipped with the above.

2. The width of the protection area is set to a length that ensures a distance that allows the vehicle body to stop without colliding with an object when an object is detected within the protection area. The transport vehicle according to claim 1.

3. The protection area is provided within a scanning range of a sensor that measures a distance to an object that may be present around the vehicle body. The transport vehicle according to claim 1.

4. A detection unit is further provided that detects the presence of an object within the protection area based on the distance to the object measured by the sensor. The transport vehicle according to claim 3.

5. A plurality of motors included in the vehicle body movement mechanism; A plurality of encoders each detecting an operating condition of the motor; Further equipped with The calculation unit calculates a speed of the vehicle body based on an output value of the encoder. The transport vehicle according to claim 1.

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