Self-driving cars

Abstract

In an autonomous vehicle that travels by detecting a guide line using a sensor unit, the distance between the sensor unit and the road surface is prevented from increasing, and collisions between the sensor unit and the road surface are prevented. The autonomous vehicle (10) includes a main body (11), wheels (12, 13) rotatably supported by the main body and rolling on a road surface, and a sensor unit (20) that detects guide lines, and the autonomous vehicle travels along the guide lines by detecting the guide lines with the sensor unit. The autonomous vehicle also includes a vertical movement mechanism (30) that moves the sensor unit up and down relative to the main body so as to prevent the distance between the sensor unit and the road surface from varying from a predetermined distance.

Description

[Technical Field]

[0001] The present invention relates to an autonomous vehicle that travels by detecting a guide line using a sensor unit. [Background technology]

[0002] For example, there is an unmanned vehicle that controls its travel by detecting a strip-shaped magnetic material laid along the route it is to travel (see Patent Document 1). The unmanned vehicle described in Patent Document 1 has sensor units attached to the bottom at both the front and rear ends of the vehicle that detect the strip-shaped magnetic material. The unmanned vehicle described in Patent Document 1 detects the strip-shaped magnetic material using the sensor unit at the front end of the vehicle while it is traveling. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 8-44426 Summary of the Invention [Problem to be solved by the invention]

[0004] The unmanned autonomous vehicle (autonomous vehicle) described in Patent Document 1 has idle wheels at both ends in the longitudinal direction and a drive wheel in the longitudinal center. When the unmanned autonomous vehicle described in Patent Document 1 finishes climbing an uphill slope, the unmanned autonomous vehicle may be supported by the drive wheels and the idle wheel at the rear end, causing the idle wheel at the front end to lift off the road surface. In this case, the distance between the sensor unit used for detection and the road surface (hereinafter referred to as the "detection distance") becomes longer than the detection distance when traveling on flat ground. As a result, the accuracy of detecting the strip-shaped magnetic material (guidance line) by the sensor unit may decrease. Note that when the unmanned autonomous vehicle described in Patent Document 1 detects the strip-shaped magnetic material using the sensor unit at the rear end of the unmanned autonomous vehicle while traveling, the following problem occurs. Specifically, when the unmanned autonomous vehicle described in Patent Document 1 begins to descend a downhill slope, the unmanned autonomous vehicle may be supported by the idle wheel at the front end and the drive wheels, causing the idle wheel at the rear end to lift off the road surface. In this case, the detection distance also becomes longer than the detection distance when traveling on flat ground.

[0005] In the unmanned autonomous vehicle described in Patent Document 1, if the front sensor unit is attached ahead of the front idle wheel, the following problems occur. That is, when the unmanned autonomous vehicle starts to climb an uphill slope, the front sensor unit may collide with the road surface of the uphill slope. Also, when the unmanned autonomous vehicle finishes descending a downhill slope, the front sensor unit may collide with the road surface of flat ground. Note that, in the unmanned autonomous vehicle described in Patent Document 1, if the sensor unit is attached between the front idle wheel and the drive wheel, or between the drive wheel and the rear idle wheel, the following problems occur. That is, when the unmanned autonomous vehicle finishes climbing an uphill slope, the sensor unit may collide with the end of the uphill slope. Also, when the unmanned autonomous vehicle starts to descend a downhill slope, the sensor unit may collide with the beginning of the downhill slope.

[0006] The present invention has been made to solve the above-mentioned problems, and its main purpose is to prevent the distance between the sensor unit and the road surface from increasing and to prevent collisions between the sensor unit and the road surface in an autonomous vehicle that moves by detecting guide lines using a sensor unit. [Means for solving the problem]

[0007] The first means for solving the above problem is: An autonomous vehicle (10) comprising: a main body (11); wheels (12, 13) rotatably supported by the main body and rolling on a road surface; and a sensor unit (20) for detecting a guide line, the autonomous vehicle detecting the guide line by the sensor unit and traveling along the guide line, A vertical movement mechanism (30) is provided for moving the sensor unit up and down relative to the main body so as to prevent the distance between the sensor unit and the road surface from varying from a predetermined distance.

[0008] The second method is An autonomous vehicle (10) comprising: a main body (11); wheels (12, 13) rotatably supported by the main body and rolling on a road surface; and a sensor unit (20) for detecting a guide line, the autonomous vehicle detecting the guide line by the sensor unit and traveling along the guide line, A vertical movement mechanism (30) is provided for moving the sensor unit up and down relative to the main body so as to bring the distance between the sensor unit and the road surface closer to a predetermined distance.

[0009] According to the configurations of the first and second means, the autonomous vehicle detects the guide line using the sensor unit and travels along the guide line on flat ground or on a slope. At this time, the autonomous vehicle travels by rolling the wheels rotatably supported by the main body on the road surface. Therefore, the distance between the part of the bottom of the main body where the sensor unit is located (hereinafter referred to as the "unit location part") and the road surface changes depending on the state of the road surface on flat ground or on a slope, supporting the main body via the wheels.

[0010] Here, in the first means, the vertical movement mechanism moves the sensor unit up and down relative to the main body so as to prevent the distance between the sensor unit and the road surface from changing from a predetermined distance. In the second means, the vertical movement mechanism moves the sensor unit up and down relative to the main body so as to bring the distance between the sensor unit and the road surface closer to the predetermined distance. Therefore, even if the distance between the unit placement portion and the road surface increases when the autonomous vehicle finishes ascending an uphill slope or starts descending a downhill slope, the distance between the sensor unit and the road surface can be prevented from becoming longer than the predetermined distance. Furthermore, even if the distance between the unit placement portion and the road surface decreases when the autonomous vehicle starts ascending an uphill slope or finishes descending a downhill slope, the distance between the sensor unit and the road surface can be prevented from becoming shorter than the predetermined distance. Therefore, in the autonomous vehicle, the distance between the sensor unit and the road surface can be prevented from increasing and a collision between the sensor unit and the road surface can be prevented. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 10 is a schematic diagram showing a side view of an autonomous vehicle according to a comparative example. [Figure 2] FIG. 10 is a schematic diagram showing the front of an autonomous vehicle of a comparative example. [Figure 3] FIG. 10 is a schematic diagram showing a state in which a sensor unit of an autonomous vehicle of a comparative example collides with an uphill road surface at the start of going uphill. [Figure 4] FIG. 10 is a schematic diagram showing how the distance between the sensor unit and the flat road surface becomes longer at the end of an uphill climb in an autonomous vehicle of the comparative example. [Figure 5] FIG. 10 is a schematic diagram showing a state in which a sensor unit of an autonomous vehicle of a comparative example collides with a flat road surface at the end of a downhill slope. [Figure 6] FIG. 10 is a schematic diagram showing how the distance between the sensor unit and the road surface of a downhill slope increases at the start of a downhill descent in an autonomous vehicle of a comparative example. [Figure 7] FIG. 10 is a schematic diagram showing a state in which a sensor unit of an autonomous vehicle of a comparative example collides with a step when the autonomous vehicle starts to climb the step. [Figure 8]FIG. 10 is a schematic diagram showing how the distance between the sensor unit and the flat road surface becomes longer when the autonomous vehicle of the comparative example starts to descend a step. [Figure 9] 10A and 10B are schematic diagrams illustrating a state in which the distance between the sensor unit and the rough road surface increases when the self-driving vehicle of the comparative example is traveling on rough ground, and a state in which the sensor unit collides with the rough road surface. [Figure 10] Schematic diagram showing the side of an autonomous vehicle. [Figure 11] FIG. [Figure 12] FIG. 10 is a perspective view schematically showing a modified example of the vertical movement mechanism. [Figure 13] FIG. 10 is a perspective view schematically showing another modified example of the vertical movement mechanism. [Figure 14] FIG. 10 is a perspective view schematically showing another modified example of the vertical movement mechanism. [Figure 15] FIG. 10 is a side view schematically showing another modified example of the vertical movement mechanism. [Figure 16] FIG. 10 is a side view schematically showing another modified example of the vertical movement mechanism. [Figure 17] FIG. 10 is a schematic diagram showing a side view of a modified example of an autonomous vehicle. [Figure 18] FIG. 10 is a schematic diagram showing a state in which a sensor unit of an autonomous vehicle of a comparative example collides with the end of an uphill slope at the end of the uphill slope. [Figure 19] FIG. 10 is a schematic diagram showing a state in which a sensor unit of an autonomous vehicle of a comparative example collides with the starting end of a downhill slope at the start of the downhill slope. [Figure 20] FIG. 10 is a schematic diagram showing a side view of another modified example of an autonomous vehicle. [Figure 21] FIG. 10 is a schematic diagram showing a side view of another modified example of an autonomous vehicle. [Figure 22] FIG. 10 is a schematic diagram showing a side view of another modified example of an autonomous vehicle. [Figure 23] FIG. 10 is a side view schematically showing another modified example of the vertical movement mechanism. DETAILED DESCRIPTION OF THE INVENTION

[0012] An embodiment embodied in an automatic guided vehicle (AGV) guided by magnetic tape in a factory, warehouse, etc. will be described below with reference to the drawings. The automatic guided vehicle is, for example, an unmanned guided vehicle or an unmanned guided robot. Note that the automatic guided vehicle may also be a manned guided vehicle or a manned guided robot.

[0013] 1, an autonomous vehicle 910 of the comparative example includes a main body 911, a pair of left and right drive wheels 12, a pair of left and right driven wheels 13, and a sensor unit 20. The pair of left and right drive wheels 12 and the pair of left and right driven wheels 13 are rotatably supported by the main body 911. The pair of left and right drive wheels 12 and the pair of left and right driven wheels 13 roll on the road surface of a road.

[0014] The main body 911 is formed, for example, in the shape of a hollow rectangular parallelepiped. Inside the main body 911, motors (not shown) are provided to rotate the drive wheels 12. The direction of travel (driving state) of the autonomous vehicle 910 is controlled by creating a difference between the rotational speed at which each motor rotates the left drive wheel 12 and the rotational speed at which each motor rotates the right drive wheel 12. The autonomous vehicle 910 is, for example, a front-wheel drive vehicle in which the pair of drive wheels 12 are front wheels and the pair of driven wheels 13 are rear wheels. The pair of left and right driven wheels 13 rotate as the autonomous vehicle 910 travels.

[0015] A sensor unit 20 is fixed to the bottom of the front end (front part) of the main body 911. Generally, in an autonomous vehicle 910, the sensor unit 20 detects the magnetic tape ahead of the drive wheels 12, and the drive wheels 12 are controlled based on the detection results. For this reason, the sensor unit 20 is disposed in front of the drive wheels. The part of the bottom of the main body 911 where the sensor unit 20 is disposed is the unit disposition part 911a. In order for the sensor unit 20 to accurately detect the magnetic tape, the sensor unit 20 is fixed to the main body 911 at a position as close to the road surface as possible.

[0016] As shown in the front view of FIG. 2, the sensor unit 20 includes, for example, 16 magnetic sensors S1 to S16. The magnetic sensors S1 to S16 are arranged horizontally in a direction perpendicular to the straight-ahead direction of the autonomous vehicle 910. That is, the magnetic sensors S1 to S16 are arranged in the left-right direction of the autonomous vehicle 910. The magnetic sensors S1 to S16 are arranged at equal intervals in order from the right end to the left end of the autonomous vehicle 910. The magnetic sensors S1 to S16 are turned on when a magnetic tape is present directly below them, and are turned off when no magnetic tape is present directly below them. That is, the magnetic sensors S1 to S16 detect only the magnetic tape directly below them (the magnetic tape directly below them).

[0017] For example, when the autonomous vehicle 910 is instructed to go straight, the autonomous vehicle 910 controls each of the drive wheels 12 of the autonomous vehicle 910 so that the center in the left-right direction of the detection range, which is the range where the magnetic sensors that detected the magnetic tape are continuous, coincides with (approaches) the center in the left-right direction of the autonomous vehicle 910. As a result, the autonomous vehicle 910 goes straight along the magnetic tape.

[0018] As described above, the sensor unit 20 is disposed in front of the drive wheels 12 and is fixed to the main body 911 at a position as close to the road surface as possible. For this reason, the following problems arise when the autonomous vehicle 910 of the comparative example travels on an uphill slope, a downhill slope, or a road with steps or large irregularities.

[0019] As shown in FIG. 3, when the autonomous vehicle 910 of the comparative example starts to climb the uphill slope UH, the distance between the unit placement portion 911a and the road surface Su of the uphill slope UH becomes shorter, making the sensor unit 20 more likely to collide with the road surface Su.

[0020] As shown in FIG. 4, when the autonomous vehicle 910 of the comparative example finishes climbing the uphill slope UH, the distance between the unit placement portion 911a and the road surface Sf of the flat ground FL increases, and the distance between the sensor unit 20 and the road surface Sf also increases.

[0021] As shown in FIG. 5, when the autonomous vehicle 910 of the comparative example finishes descending the downhill slope DH, the distance between the unit placement portion 911a and the road surface Sf of the flat ground FL becomes shorter, making the sensor unit 20 more likely to collide with the road surface Sf.

[0022] As shown in FIG. 6, when the autonomous vehicle 910 of the comparative example starts to descend the downhill slope DH, the distance between the unit placement portion 911a and the road surface Sd of the downhill slope DH increases, and the distance between the sensor unit 20 and the road surface Sd also increases.

[0023] As shown in FIG. 7, when the autonomous vehicle 910 of the comparative example starts to climb the step ST, the sensor unit 20 is likely to collide with the step ST.

[0024] As shown in FIG. 8, when the autonomous vehicle 910 of the comparative example starts to descend a step ST, the distance between the sensor unit 20 and the road surface Sf of the flat ground FL becomes longer.

[0025] As shown in Figure 9, when the autonomous vehicle 910 of the comparative example travels through rough terrain BL, the distance between the sensor unit 20 and the road surface Sb of the rough terrain BL becomes longer, and the sensor unit 20 becomes more likely to collide with the road surface Sb of the rough terrain BL.

[0026] 10 and 11, the autonomous vehicle 10 of this embodiment is provided with a vertical movement mechanism 30 that moves the sensor unit 20 up and down relative to the main body 11. Note that only a portion of the main body 11 is shown in FIG. 11. The configuration and control of the autonomous vehicle 10 are similar to those of the autonomous vehicle 910 of the comparative example, except that the autonomous vehicle 10 is provided with the vertical movement mechanism 30. The method by which the autonomous vehicle 10 controls the pair of drive wheels 12 based on the detection results of the sensor unit 20 is the same as that of the autonomous vehicle 910 of the comparative example. That is, the autonomous vehicle 10 detects a magnetic tape M1 (corresponding to a guide line) using the sensor unit 20, and travels along the magnetic tape M1.

[0027] The guide line that guides the autonomous vehicle 10 is not limited to the magnetic tape M1, but may be a line having a conductive wire that generates magnetism when electricity is applied, a reflective tape that reflects light, a line having a light-emitting member, etc. The sensor unit 20 may be any sensor unit that detects magnetism or light in accordance with the characteristics of the guide line. Furthermore, the control method for causing the autonomous vehicle 10 to travel along the guide line based on the results of detection of the guide line by the sensor unit 20 can be changed as desired.

[0028] The following description will focus on the configuration related to the vertical movement mechanism 30. In the autonomous vehicle 10, the same parts as those in the autonomous vehicle 910 of the comparative example will be given the same reference numerals and the description thereof will be incorporated herein.

[0029] The main body 11 is formed, for example, in the shape of a hollow rectangular parallelepiped. In this embodiment, the up-and-down movement mechanism 30 and the sensor unit 20 are arranged in front of the drive wheels 12 on the main body 11. The part of the bottom of the main body 11 where the sensor unit 20 is arranged is the unit arrangement part 11a. The unit arrangement part 11a is the part of the bottom of the main body 11 that is located above the sensor unit 20. The sensor unit 20 detects the magnetic tape M1.

[0030] The vertical movement mechanism 30 includes a sensor wheel 31, a support member 32, a first guide member 33, a second guide member 34, and a pair of springs 35. In other words, the vertical movement mechanism 30 is a passive mechanism that does not have a power source.

[0031] A first guide member 33 and a second guide member 34 are fixed (attached) to the main body 11. The first guide member 33 and the second guide member 34 are formed in an annular shape, and their centers in the horizontal direction coincide with each other.

[0032] The support member 32 has a shaft portion 32a, a mounting portion 32b, and a supported portion 32c.

[0033] The shaft portion 32a is formed, for example, in a cylindrical shape. The inner diameters of the first guide member 33 and the second guide member 34 are set to be slightly larger than the outer diameter of the shaft portion 32a. The shaft portion 32a is inserted through the first guide member 33 and the second guide member 34. The shaft portion 32a is supported by the first guide member 33 and the second guide member 34 so as to be slidable in the up and down direction. Movement of the shaft portion 32a in directions other than the up and down direction (the direction perpendicular to the bottom surface of the main body 11) is restricted.

[0034] The lower end of shaft portion 32a protrudes downward below the bottom of main body 11. Mounting portion 32b extends from the lower end of shaft portion 32a toward the front of main body 11. Mounting portion 32b is formed, for example, in a cylindrical shape, but the shape of mounting portion 32b is arbitrary. Sensor unit 20 is mounted to mounting portion 32b (more specifically, the lower part of mounting portion 32b). For example, the center portion of sensor unit 20 in the longitudinal direction is fixed to mounting portion 32b. In this way, support member 32 supports sensor unit 20.

[0035] The supported portion 32c extends downward from the front end of the attached portion 32b. The supported portion 32c is formed, for example, in a cylindrical shape, but the shape of the supported portion 32c is arbitrary. The sensor wheel 31 is rotatably attached to the lower part of the supported portion 32c. As a result, the supported portion 32c, and therefore the support member 32, is supported by the sensor wheel 31.

[0036] The sensor wheel 31 (corresponding to the predetermined wheel and the contact member) is a disk-shaped wheel that contacts, for example, the road surface Sf. The sensor wheel 31 is capable of rolling in the direction of travel of the autonomous vehicle 10, following the road surface Sf. The outer peripheral surface 31a (corresponding to the contact portion) of the sensor wheel 31 smoothly contacts the road surface Su of the uphill slope UH, the step ST, the road surface Sb of the rough ground BL, etc.

[0037] A pair of springs 35 (corresponding to biasing members) bias the sensor unit 20 downward (in the direction away from the main body 11) relative to the main body 11. The pair of springs 35 are attached to both longitudinal ends (near both ends) of the sensor unit 20. The pair of springs 35 bias the sensor unit 20 downward relative to the main body 11, thereby biasing the support member 32 to which the sensor unit 20 is attached, and ultimately the sensor wheel 31, downward.

[0038] This allows the sensor wheel 31 to abut against the road surfaces Sf, Su, Sd, and Sb of the road, regardless of the shape of the road surface of the road on which the autonomous vehicle 10 runs. The diameter of the sensor wheel 31, the dimensions of the support member 32, and the mounting position of the sensor unit 20 relative to the support member 32 are set so that when the sensor wheel 31 abuts against the road surfaces Sf, Su, Sd, and Sb, the distance between the underside 20a of the sensor unit 20 and the road surfaces Sf, Su, Sd, and Sb is a predetermined distance d1. The predetermined distance d1 is set so that the sensor unit 20 is unlikely to come into contact with the road surface Sb, which may be a step ST or rough ground BL, and so that the distance between the sensor unit 20 and the road surfaces Sf, Su, Sd, and Sb is as short as possible. For example, the predetermined distance d1 is set to be longer than the radius of the sensor wheel 31 but shorter than the diameter.

[0039] With the above configuration, the vertical movement mechanism 30 moves the sensor unit 20 up and down relative to the main body 11 so as to prevent the distance between the sensor unit 20 and the road surfaces Sf, Su, Sd, and Sb from changing from the predetermined distance d1. In other words, the vertical movement mechanism 30 moves the sensor unit 20 up and down relative to the main body 11 so as to bring the distance between the sensor unit 20 and the road surfaces Sf, Su, Sd, and Sb closer to the predetermined distance d1.

[0040] For example, when the autonomous vehicle 10 starts to climb the uphill slope UH shown in Fig. 3, the sensor wheels 31 roll along the road surface Su of the uphill slope UH, causing the sensor unit 20 to move upward so as to approach the main body 11. This maintains the distance between the sensor unit 20 and the road surface Su at approximately the predetermined distance d1.

[0041] 4, the sensor unit 20 moves downward away from the main body 11 until the sensor wheel 31 abuts on the road surface Sf of the flat ground FL. This maintains the distance between the sensor unit 20 and the road surface Sf at approximately the predetermined distance d1.

[0042] 5, the sensor wheels 31 roll along the road surface Sf of the flat ground FL, causing the sensor unit 20 to move upward so as to approach the main body 11. This maintains the distance between the sensor unit 20 and the road surface Sf at approximately the predetermined distance d1.

[0043] 6, the sensor unit 20 moves downward away from the main body 11 until the sensor wheel 31 abuts on the road surface Sd of the downhill slope DH. This maintains the distance between the sensor unit 20 and the road surface Sd at approximately the predetermined distance d1.

[0044] 7, the sensor wheels 31 roll over the step ST, causing the sensor unit 20 to move upward and approach the main body 11. This maintains the distance between the sensor unit 20 and the step ST at approximately the predetermined distance d1.

[0045] 8, the sensor unit 20 moves downward away from the main body 11 until the sensor wheel 31 abuts on the road surface Sf of the flat ground FL. This maintains the distance between the sensor unit 20 and the road surface Sf at approximately the predetermined distance d1.

[0046] 9, the sensor unit 20 moves up and down relative to the main body 11 so that the sensor wheel 31 follows the road surface Sb of the rough land BL. This maintains the distance between the sensor unit 20 and the road surface Sb at approximately the predetermined distance d1.

[0047] The present embodiment described above in detail has the following advantages.

[0048] Even if the distance between the unit arrangement portion 11a and the road surfaces Sf, Sd increases when the autonomous vehicle 10 finishes ascending the uphill slope UH or starts descending the downhill slope DH, the distance between the sensor unit 20 and the road surfaces Sf, Sd can be prevented from becoming longer than the predetermined distance d1. Furthermore, even if the distance between the unit arrangement portion 11a and the road surfaces Su, Sf decreases when the autonomous vehicle 10 starts ascending the uphill slope UH or finishes descending the downhill slope DH, the distance between the sensor unit 20 and the road surfaces Su, Sf can be prevented from becoming shorter than the predetermined distance d1. Therefore, in the autonomous vehicle 10, the distance between the sensor unit 20 and the road surfaces Sf, Sd can be prevented from increasing, and collisions between the sensor unit 20 and the road surfaces Su, Sf can be prevented. Furthermore, in the autonomous vehicle 10, the distance between the sensor unit 20 and the road surface Sb of the rough terrain BL can be prevented from increasing, and collisions between the sensor unit 20 and the road surface Sb can be prevented.

[0049] The vertical movement mechanism 30 is a passive mechanism that does not have a power source, and therefore the configuration can be simplified and energy consumption can be reduced.

[0050] The sensor wheels 31 that come into contact with the road surfaces Sf, Su, Sd, and Sb can stably support the support members 32. Supporting the sensor unit 20 with the support members 32 allows the sensor unit 20 to be stably supported on the road surfaces Sf, Su, Sd, and Sb. This makes it possible to stably prevent the distance between the sensor unit 20 and the road surfaces Sf, Su, Sd, and Sb from changing from the predetermined distance d1. Furthermore, it is possible to stably bring the distance between the sensor unit 20 and the road surfaces Sf, Su, Sd, and Sb closer to the predetermined distance d1.

[0051] The sensor wheel 31 has (includes) an outer peripheral surface 31a that smoothly contacts the road surfaces Sf, Su, Sd, and Sb, thereby reducing the impact when the sensor wheel 31 contacts the road surface Su or step ST on the uphill slope UH.

[0052] The wheels (specifically, the sensor wheels 31), which are general-purpose parts, can be used to support the support members 32 and to smoothly contact the road surfaces Sf, Su, Sd, and Sb.

[0053] When the distance between the unit placement portion 11a and the road surfaces Sf, Su, Sd, and Sb becomes long, the spring 35 urges the sensor unit 20 downward relative to the main body 11, thereby easily preventing the distance between the sensor unit 20 and the road surfaces Sf, Su, Sd, and Sb from becoming longer than the predetermined distance d1.

[0054] The above embodiment can be modified as follows: The same parts as those in the above embodiment are denoted by the same reference numerals and the description thereof will be incorporated herein.

[0055] As shown in FIG. 12, the vertical movement mechanism 30 may include two sensor wheels 31. In this case, the mounting portion 32b is formed, for example, in a "U" shape and has a bilaterally symmetrical shape. The sensor unit 20 is mounted to the mounting portion 32b (more specifically, the lower part of the mounting portion 32b). For example, the sensor unit 20 is fixed to the mounting portion 32b at two points equidistant from the center in the longitudinal direction. In this way, the support member 32 supports the sensor unit 20. With the above configuration, the sensor wheels 31 can be prevented from rolling on the magnetic tape M1. Furthermore, the sensor unit 20 can be prevented from tilting left or right relative to the road surfaces Sf, Su, Sd, and Sb.

[0056] Instead of the pair of springs 35, a pair of elastic rubbers (corresponding to a biasing member) that biases the sensor unit 20 downward relative to the main body 11 (in the direction away from the main body 11) may be used.

[0057] Instead of the pair of springs 35 shown in FIG. 11 , the vertical movement mechanism 30 may include a pair of dampers 37, as shown in FIG. 13 . The dampers 37 have, for example, a cylinder filled with oil or gas, and absorb energy as a piston moves within the cylinder. In this case, the sensor unit 20 moves downward relative to the main body 11 due to gravity until the sensor wheels 31 contact the road surfaces Sf, Su, Sd, and Sb. When the sensor wheels 31 receive a reaction force from the road surfaces Sf, Su, Sd, and Sb, causing the sensor unit 20 to vibrate up and down, the dampers 37 damp the up and down vibrations of the sensor unit 20. This suppresses fluctuations in the distance between the sensor unit 20 and the road surfaces Sf, Su, Sd, and Sb, allowing the sensor unit 20 to stably detect the magnetic tape M1.

[0058] 14, the vertical movement mechanism 30 may include a pair of springs 35 and a pair of dampers 37. In this case, the ability of the sensor wheels 31 to follow the road surfaces Sf, Su, Sd, and Sb can be improved, and the sensor unit 20 can detect the magnetic tape M1 more stably.

[0059] 15 , the vertical movement mechanism 30 may be attached to the main body 11 so that the shaft portion 32a of the support member 32 is oblique to the main body 11. In this case, the vertical movement mechanism 30 moves the support member 32 obliquely up and down relative to the main body 11, thereby moving the sensor unit 20 obliquely up and down relative to the main body 11.

[0060] Instead of the sensor wheel 31 of FIG. 10, the vertical movement mechanism 30 may include a plate-shaped member 41 with a warped tip, as shown in FIG. 16. The plate-shaped member 41 (corresponding to the contact member) has a flat portion 41a and a warped portion 41b. The flat portion 41a is formed, for example, in the shape of a rectangular plate. The longitudinal direction of the flat portion 41a coincides with the front-rear direction of the main body 11. The warped portion 41b (corresponding to the contact portion) extends forward from the front end of the flat portion 41a and is warped upward. The warped portion 41b is formed in an arc shape and smoothly contacts the road surfaces Sf, Su, Sd, and Sb. This makes it possible to reduce the impact when the plate-shaped member 41 contacts the road surface Su or a step ST on the uphill slope UH.

[0061] The plate-like member 41 is brought into contact with the road surfaces Sf, Su, Sd, and Sb of the road, regardless of the shape of the road surface of the road on which the autonomous vehicle 10 travels. The thickness of the plate-like member 41, the dimensions of the support member 32, and the mounting position of the sensor unit 20 relative to the support member 32 are set so that when the plate-like member 41 is in contact with the road surfaces Sf, Su, Sd, and Sb, the distance between the lower surface 20a of the sensor unit 20 and the road surfaces Sf, Su, Sd, and Sb is a predetermined distance d1. The predetermined distance d1 is set so that the sensor unit 20 is unlikely to come into contact with the road surface Sb, which may include steps ST or rough ground BL, and so that the distance between the sensor unit 20 and the road surfaces Sf, Su, Sd, and Sb is as short as possible. For example, the predetermined distance d1 is set to be longer than the vertical width of the warped portion 41b but shorter than twice the vertical width of the warped portion 41b.

[0062] As shown in FIG. 17 , the autonomous vehicle 10 may include two sets of sensor units 20 and vertical movement mechanisms 30. For example, when the autonomous vehicle 10 moves forward (to the left in FIG. 17 ), the sensor unit 20 on the front side (left side in FIG. 17 ) detects the magnetic tape M1 and runs along the magnetic tape M1, stopping the sensor unit 20 on the rear side (right side in FIG. 17 ). When the autonomous vehicle 10 moves backward (to the right in FIG. 17 ), the sensor unit 20 on the rear side (right side in FIG. 17 ) detects the magnetic tape M1 and runs along the magnetic tape M1, stopping the sensor unit 20 on the front side (left side in FIG. 17 ). In these cases, it is possible to prevent the distance between the front and rear sensor units 20 and the road surfaces Sf, Su, Sd, and Sb in the autonomous vehicle 10 from increasing, and to prevent collisions between the front and rear sensor units 20 and the road surfaces Sf, Su, Sd, and Sb.

[0063] 18, the sensor unit 20 may be attached between the drive wheels 12 and the driven wheels 13 at the bottom of the main body 911 of the autonomous vehicle 910 of the comparative example. In this case, when the autonomous vehicle 910 of the comparative example finishes climbing an uphill slope UH, the distance between the unit placement portion 911a and the end of the uphill slope UH (the boundary between the uphill slope UH and flat ground FL) becomes shorter, making it more likely that the sensor unit 20 will collide with the end of the uphill slope UH. Also, as shown in FIG. 19, when the autonomous vehicle 910 of the comparative example starts descending a downhill slope DH, the distance between the unit placement portion 911a and the start of the downhill slope DH (the boundary between flat ground FL and the downhill slope DH) becomes shorter, making it more likely that the sensor unit 20 will collide with the start of the downhill slope DH.

[0064] In these cases, it is also effective for the autonomous vehicle 10 to be provided with a vertical movement mechanism 30, as shown in Fig. 20. When the autonomous vehicle 10 finishes climbing the uphill slope UH shown in Fig. 18, the sensor unit 20 moves up and down relative to the main body 11 so that the sensor wheel 31 follows the road surface Su of the uphill slope UH and the road surface Sf of the flat ground FL. This maintains the distance between the sensor unit 20 and the road surfaces Su, Sf at approximately the predetermined distance d1. When the autonomous vehicle 10 starts to descend the downhill slope DH shown in Fig. 19, the sensor unit 20 moves up and down relative to the main body 11 so that the sensor wheel 31 follows the road surface Sf of the flat ground FL and the road surface Sd of the downhill slope DH. This maintains the distance between the sensor unit 20 and the road surfaces Sf, Sd at approximately the predetermined distance d1.

[0065] 21 and 22, an autonomous vehicle 10 may have driven wheels 13 at the front and rear ends of a main body 11, and a driving wheel 12 at the center in the fore-and-aft direction of the main body 11. A sensor unit 20 may be attached to the bottom of the main body 11 between the driving wheel 12 and one of the driven wheels 13. In these cases, the same effects as those of the autonomous vehicle 10 in FIG. 20 can be achieved.

[0066] The vertical movement mechanism 30 may not include the supported portion 32c, the sensor wheel 31, and the spring 35 shown in FIG. 10, but may include an actuator 38 and a distance sensor 39 as shown in FIG. 23. The actuator 38 is driven by electricity and moves the support member 32 up and down by electromagnetic force. The distance sensor 39 is attached to, for example, the bottom surface of the unit placement portion 11a. The distance sensor 39 detects the distance between the distance sensor 39 and the road surfaces Sf, Su, Sd, and Sb, and further the distance between the lower surface 20a of the sensor unit 20 and the road surfaces Sf, Su, Sd, and Sb. Based on the distance detected by the distance sensor 39, the actuator 38 moves the support member 32 up and down so as to bring the distance between the lower surface 20a of the sensor unit 20 and the road surfaces Sf, Su, Sd, and Sb closer to a predetermined distance d1. In other words, the vertical movement mechanism 30 moves the sensor unit 20 up and down relative to the main body 11 so as to prevent the distance between the sensor unit 20 and the road surfaces Sf, Su, Sd, and Sb from changing from the predetermined distance d1. The vertical movement mechanism 30 in Fig. 23 is an active mechanism having a power source.

[0067] The shape of the main body 11 is not limited to a hollow rectangular parallelepiped, but may be changed as appropriate to a hollow cube, a hollow hexagonal prism, a hollow cylinder, or the like.

[0068] The above-described embodiment and modifications may be combined within the scope of possible combinations.

[0069] Characteristic configurations extracted from the above-described embodiments and modifications will be described below. [Configuration 1] An autonomous vehicle (10) comprising: a main body (11); wheels (12, 13) rotatably supported by the main body and rolling on a road surface; and a sensor unit (20) for detecting a guide line, the autonomous vehicle detecting the guide line by the sensor unit and traveling along the guide line, The autonomous vehicle is provided with a vertical movement mechanism (30) that moves the sensor unit up and down relative to the main body so as to prevent the distance between the sensor unit and the road surface from changing from a predetermined distance. [Configuration 2] An autonomous vehicle (10) comprising: a main body (11); wheels (12, 13) rotatably supported by the main body and rolling on a road surface; and a sensor unit (20) for detecting a guide line, the autonomous vehicle detecting the guide line by the sensor unit and traveling along the guide line, The autonomous vehicle is provided with a vertical movement mechanism (30) that moves the sensor unit up and down relative to the main body so as to bring the distance between the sensor unit and the road surface closer to a predetermined distance. [Configuration 3] 3. The autonomous vehicle according to claim 1, wherein the vertical movement mechanism is a passive mechanism that does not have a power source. [Configuration 4] The self-driving vehicle according to any one of configurations 1 to 3, wherein the vertical movement mechanism comprises a contact member (31, 41) that contacts the road surface, and a support member (32) that is supported by the contact member and supports the sensor unit. [Configuration 5] 5. The autonomous vehicle according to claim 4, wherein the contact member includes a contact portion (31a, 41a) that smoothly contacts the road surface. [Configuration 6] 6. The autonomous vehicle according to claim 4 or 5, wherein the contact member is a predetermined wheel (31) that rolls along the road surface. [Configuration 7] 7. The autonomous vehicle according to any one of configurations 1 to 6, wherein the vertical movement mechanism includes a biasing member (35) that biases the sensor unit downward relative to the main body. [Configuration 8] 8. The autonomous vehicle according to any one of configurations 1 to 7, wherein the vertical movement mechanism includes a damper (37) that damps vertical vibrations of the sensor unit. [Explanation of symbols]

[0070] 10...Autonomous vehicle, 11...Main body, 12...Drive wheel, 13...Driven wheel, 20...Sensor unit, 30...Up-down movement mechanism

Claims

1. An autonomous vehicle (10) comprising: a main body (11); wheels (12, 13) rotatably supported by the main body and rolling on a road surface; and a sensor unit (20) for detecting a guide line, the autonomous vehicle detecting the guide line by the sensor unit and traveling along the guide line, An autonomous vehicle comprising a vertical movement mechanism (30) that moves the sensor unit up and down relative to the main body so as to prevent the distance between the sensor unit and the road surface from changing from a predetermined distance.

2. An autonomous vehicle (10) comprising: a main body (11); wheels (12, 13) rotatably supported by the main body and rolling on a road surface; and a sensor unit (20) for detecting a guide line, the autonomous vehicle detecting the guide line by the sensor unit and traveling along the guide line, The autonomous vehicle is provided with a vertical movement mechanism (30) that moves the sensor unit up and down relative to the main body so as to bring the distance between the sensor unit and the road surface closer to a predetermined distance.

3. 3. The autonomous vehicle according to claim 1, wherein the vertical movement mechanism is a passive mechanism that does not have a power source.

4. 3. The autonomous vehicle according to claim 1, wherein the vertical movement mechanism comprises a contact member (31, 41) that contacts the road surface, and a support member (32) that is supported by the contact member and supports the sensor unit.

5. The autonomous vehicle according to claim 4, wherein the contact member includes a contact portion (31a, 41a) that smoothly contacts the road surface.

6. 5. The autonomous vehicle according to claim 4, wherein the contact member is a predetermined wheel (31) that rolls along the road surface.

7. 3. The autonomous vehicle according to claim 1, wherein the vertical movement mechanism includes a biasing member (35) that biases the sensor unit downward relative to the main body.

8. 3. The autonomous vehicle according to claim 1, wherein the vertical movement mechanism includes a damper (37) that damps vertical vibrations of the sensor unit.

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