Travel device

Abstract

[Problem] To satisfy torque requirements and achieve low noise at the time of travel even when wheels having a small diameter are used. [Solution] A travel device 1 comprising: a chassis 10; a first motor 11 and a second motor 12 mounted to the chassis 10; and a first wheel 13 and a second wheel 14 attached respectively to the output shafts 11b, 12b of the first motor 11 and the second motor 12. The output shafts 11b, 12b of each of the first motor 11 and the second motor 12 are mounted to the chassis 10 at an angle inclined with respect to the ground contact surfaces of the first wheel 13 and the second wheel 14.

Description

TECHNICAL FIELD

[0001] The present invention relates to a motor-driven travel device that travels on a pre-installed lane.BACKGROUND ART

[0002] Model automobiles are known that transmit power from a motor to wheels via gears and shafts (see, for example, Patent Literature 1). This kind of model automobile basically moves straight; however, in a case in which a lane with left and right side walls is used, the model automobile can be made to travel along this lane.CITATION LISTPatent LiteraturePatent Literature 1: JP 2006-198206 ASUMMARY OF INVENTIONTechnical Problem

[0004] While it is necessary to employ a motor with a relatively large diameter in order to obtain a large torque, there are cases in which it is not possible to mount large-diameter wheels on a travel device due to limitations on, for example, a width of a lane or a height of side walls. In this case, first attaching a small diameter wheel directly to an output shaft of a large diameter motor is considered; however, in that case, small diameter wheels tend to float off a travel surface, making it difficult to sufficiently transmit torque from the motor to the travel surface. Therefore, as an alternative, placement of gears or shafts between the motor and the wheels is considered. However, in that case, rotation noise from rotating gears and shafts will be generated, making it difficult to maintain low noise. Thus, in a case of using a large diameter motor and small diameter wheels, it is difficult to satisfy torque requirements and achieve low noise. Furthermore, when gears or shafts are required as a power transmission mechanism for a travel device, the travel device cannot be made sufficiently compact, and this may result in breakdowns.

[0005] In addition, in a case in which the travel device is made to travel within a lane with left and right side walls, no major problems arise as long as the travel device moves completely straight; however, for example, in a case in which there is a deviation in the weight balance of the vehicle body, a wheel mounting position, or wear of the tires, the travel device may not move straight, but may travel to the left or right. In reality, it is extremely difficult to make a travel device move completely straight, and most travel devices tend to have a bias in the direction of travel. In addition, to ensure that the vehicle body moves straight, sensors may be mounted inside or outside the vehicle body to detect errors in the attitude or straight movement of the vehicle body, and these errors may be corrected during control. However, there are cases in which it is not possible to install a sensor that detects the direction of travel of the vehicle body and the like due to limitations such as cost and space inside the vehicle body, and problems such as the difficulty of detecting the attitude and direction of travel of the vehicle body from the outside due to spatial conditions in which the vehicle body is traveling (such as traveling in a dark place), make it impossible to control the attitude and straight movement of the vehicle body. In this case, the travel device will travel along the lane while continuing to contact either the left or right side wall of the lane. In this case, problems may occur such as a decrease in traveling speed of the travel device and uneven wear on the vehicle body and tires. For this reason, there is a demand to prevent a state in which the travel device continues to travel while in contact with either the left or right side wall of the lane.

[0006] Therefore, a first problem to be solved by the present invention is to satisfy torque requirements and achieve low noise during travel when small diameter wheels are used. In addition, a second problem to be solved by the present invention is to prevent the travel device from continuing to travel biased to the left or right within the lane. An object of the present invention is to solve at least one of the first and second problems described above.Solution to Problem

[0007] The present invention relates to a travel device 1. The travel device 1 includes a chassis 10, a first motor 11, a second motor 12, a first wheel 13, and a second wheel 14. The first motor 11 and the second motor 12 are mounted on a left side and a right side of the chassis 10, respectively. The first motor 11 and the second motor 12 respectively include a rotating portion 11a, 12a and an output shaft 11b, 12b. The output shafts 11b, 12b externally output rotational forces obtained in the rotating portions 11a, 12a. Note that the traveling device 1 need only include at least the two motors 11, 12, and may further include other motors (a third motor and a fourth motor) in addition to the two motors. The first wheel 13 is attached to the output shaft 11b of the first motor 11, and the second wheel 14 is attached to the output shaft 12b of the second motor 12. Here, the first motor 11 and the second motor 12 are mounted on the chassis 10 so that their output shafts 11b, 12b are inclined at an angle relative to a ground contact surface of the first wheel 13 and the second wheel 14, respectively. Note that the “ground contact surface” referred to here is a surface that is parallel to a line segment connecting a contact point with the first wheel 13 and a contact point with the second wheel 14 on a flat surface when the travel device 1 is placed on the flat surface. In addition, “angle inclined relative to the ground contact surface” specifically means that each output shaft 11b, 12b is not parallel or perpendicular to the ground contact surface, but is inclined so that the wheel 13, 14 sides of the output shafts 11b, 12b face downward. Furthermore, each of the first wheel 13 and the second wheel 14 includes a wheel member 13a, 14a and a tire member 13b, 14b. The wheel members 13a, 14a are directly attached to the output shafts 11b, 12b of the first motor 11 and the second motor 12, respectively (they are rotatably supported by the shafts). The tire members 13b, 14b are attached to the outer periphery of the wheel members 13a, 14a, respectively. In this manner, the wheel members 13a, 14a are directly fixed to the output shafts 11b, 12b of the motors 11, 12, eliminating the need for intermediate members such as gears or shafts. The diameters of the tire members 13b, 14b of the first wheel 13 and the second wheel 14 are smaller than the diameters of the rotating portions 11a, 12a of the first motor 11 and the second motor 12.

[0008] As configured above, the travel device 1 of the present invention is equipped with two small diameter wheels 13, 14 and two large diameter motors 11, 12 for independently driving the wheels 13, 14, respectively. In a travel device 1 configured as described above, in order to ensure low noise, no gears are interposed between the motors 11, 12 and the wheels 13, 14, and the wheels 13, 14 are directly attached to the output shafts 11b, 12b of the motors 11, 12. Even in this case, by mounting the motors 11, 12 on the chassis 10 so that the output shafts 11b, 12b of the motors 11, 12 are at angles inclined relative to the ground contact surfaces of the wheels 13, 14, the small diameter wheels 13, 14 can be brought into contact with the travel surface, and the torques from the large diameter motors 11, 12 can be transmitted sufficiently to the travel surface. Therefore, according to the present invention, it is possible to satisfy the torque requirements and achieve low noise during traveling. In other words, by inclining the output shaft 11b of the first motor 11 and the output shaft 12b of the second motor 12, even in a case in which the small diameter wheels 13, 14 are directly attached to the output shafts 11b, 12b, the wheels 13, 14 can be brought into contact with the travel surface and the torques from the motors 11, 12 can be sufficiently transmitted to the travel surface. Furthermore, the wheels 13, 14 can be directly attached to the motors 11, 12, eliminating the need to interpose gears or shafts between the wheels 13, 14 and the motors 11, 12, and thus it is possible to eliminate the noise of gears rotating while traveling, thereby improving noise reduction while traveling. In addition, by eliminating intermediate members such as gears and shafts, the travel device 1 can be easily made smaller, breakdowns are less likely to occur, and maintenance is easier.

[0009] In the travel device 1 according to the present invention, the tire members 13b, 14b are preferably replaceable.

[0010] The travel device 1 according to the present invention may be configured so that the tire members 13b, 14b are in line contact with the ground contact surface. In conventional travel devices (model automobiles, and the like), tire members generally come into surface contact with the ground contact surface. In contrast, in the travel device 1 according to the present invention, the output shafts 11b, 12b of the motors 11, 12 are inclined as described above, and thus the tire members 13b, 14b come into line contact with the ground contact surface

[0011] In the travel device 1 according to the present invention, it is preferable that no gears are interposed between the first motor 11 and the first wheel 13, and no gears are interposed between the second motor 12 and the second wheel 14. As a result, as described above, it is possible to improve the noise reduction when the travel device 1 is traveling.

[0012] It is preferable that the travel device 1 according to the present invention further includes a control device 16 that controls the first motor 11 and the second motor 12 independently. More specifically, it is preferable that the control device 16 be capable of separately controlling the rotation speed of the first motor 11 and the rotation speed of the second motor 12. As a result, various controls according to the application, such as stopping only the second motor 12 while the first motor 11 is driving, or reducing the rotation speed of the first motor 11 below the rotation speed of the second motor 12 become possible.

[0013] In the travel device 1 of the present invention, it is preferable that the control device 16 regularly or randomly switches between two or more states including a state in which the rotation speed of the first motor 11 is faster than that of the second motor 12, and a state in which the rotational speed of the second motor 12 is faster than that of the first motor 11. Furthermore, the states in which the control device 16 performs switching may further include, in addition to the above two states, a state in which the rotation speed of the first motor 11 and the rotation speed of the second motor 12 are equal. In this way, by switching the rotation speeds of the first motor 11 and the second motor 12 between slow and fast, it is possible to prevent the travel device 1 from continuously contacting either the left or right side wall when the travel device 1 travels on a lane having left and right side walls. In other words, even though it is ideal for the travel device 1 to move straight, in reality, the travel device 1 often moves to the left or right due to an imbalance in weight balance or the like. Therefore, for example, even in a case in which the travel device 1 has a tendency to move to the left, the rotation speeds of the first motor 11 and the second motor 12 can be switched between slow and fast in a regular or random manner, so that the travel device 1 can be intentionally made to contact the right or left side wall. Thus, it is possible to prevent the travel device 1 from continuously contacting one of the left and right side walls in a biased manner.

[0014] A travel device 1 according to another aspect of the present invention includes a chassis 10, a first motor 11 and a second motor 12 mounted on the chassis 10, a first wheel 13 and a second wheel 14 driven by the first motor 11 and the second motor 12, and a control device 16 that independently controls the first motor 11 and the second motor 12. The control device 16 regularly or randomly switches between two or more states including a state in which the rotation speed of the first motor 11 is faster than that of the second motor 12, and a state in which the rotation speed of the second motor 12 is faster than that of the first motor 11.Advantageous Effects of Invention

[0015] According to the present invention, when small diameter wheels are used in order to make the travel device more compact, it is possible to satisfy the torque requirements and achieve low noise while traveling. In addition, according to the present invention, it is possible to prevent the travel device from continuing to travel while being biased to the left or right within a lane.BRIEF DESCRIPTION OF DRAWINGS

[0016] FIG. 1 illustrates a travel device traveling along a lane.

[0017] FIG. 2 illustrates an example of a cross-sectional structure of an entire travel device.

[0018] FIG. 3 illustrates an example of a cross-sectional structure of a drive mechanism provided in a travel device.

[0019] FIG. 4 is a perspective view illustrating an example of a drive mechanism provided in a travel device.

[0020] FIG. 5 is a side view illustrating an example of a drive mechanism provided in a travel device.

[0021] FIG. 6 is a block diagram illustrating an example of a configuration of a control device provided in a travel device.

[0022] FIG. 7 illustrates a schematic diagram of an example of basic control of a travel device, problems associated with the control, and an example of improved control.DESCRIPTION OF EMBODIMENTS

[0023] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the embodiments described below, and also includes appropriate modifications of the embodiments described below within a scope obvious to those skilled in the art.

[0024] FIG. 1 illustrates a state in which a travel device 1 travels on a lane that has been laid in advance. As illustrated in FIG. 1, the travel device 1 includes a vehicle body 2 and a dome-shaped cover 3 attached to an upper portion of the vehicle body 2. The vehicle body 2 is provided with a drive mechanism for causing the travel device 1 to travel, and a light emitting mechanism for emitting light from an LED or the like, as will be described in detail later. The travel device 1 receives a propulsive force from the drive mechanism of the vehicle body 2 and travels along a lane. This lane is provided with side walls on both left and right sides of a travel surface, and the vehicle body 2 of the travel device 1 travels while contacting the side walls of the lane. As a result, the travel device 1 moves forward while going straight or curving along the shape of the lane. In addition, the vehicle body 2 of the travel device 1 is provided with a light emitting mechanism. The cover 3 covering the vehicle body 2 is transparent or semi-transparent, and thus when the light emitting mechanism of the vehicle body 2 emits light, the light passes through the cover 3 and is visible from the outside. The cover 3 may, for example, be made of a known material such as polycarbonate or silicon. Furthermore, the cover 3 may be configured by a half mirror. The half mirror transmits light traveling from the inside to the outside and reflects light traveling from the outside to the inside. In this case, a half mirror film may be attached to an inner surface of the cover 3 made of, for example, a silicon material.

[0025] FIG. 2 is a cross-sectional view illustrating an overall structure of the travel device 1. Further, FIGS. 3 to 5 mainly illustrate a cross-sectional view, a perspective view, and a side view of the drive mechanism of the travel device 1. As illustrated in each drawing, the travel device 1 includes a chassis 10 on which various devices such as a motor and a battery (not illustrated) are mounted. When various devices are mounted on the chassis 10, the devices may be fixed using screws or bolts, or may be welded with solder or the like. The shape of the chassis 10 may be designed according to the application of the travel device 1. The chassis 10 may be made of plastic if the travel device 1 needs to be lightweight, and may be made of metal if higher rigidity is required.

[0026] The travel device 1 is provided with at least two motors 11, 12. The motors 11, 12 are independently attached to wheels 13, 14, respectively. The wheels 13, 14 rotate when the motors 11, 12 are driven by electric power supplied from a battery (not illustrated), and the travel device 1 obtains propulsive force when the wheels 13, 14 come into contact with the travel surface. In the present embodiment, the travel device 1 employs a rear-wheel drive system, and thus the motors 11, 12 are mounted at the rear of the chassis 10. In the illustrated example, based on the direction of travel of the travel device 1, a first motor 11 drives a first wheel 13 on the left side, and a second motor 12 drives a second wheel 14 on the right side. Note that the travel device 1 is not limited to a rear-wheel drive system, and may employ a front-wheel drive system.

[0027] A known motor can be used as each of the motors 11, 12. More specifically, each of the motors 11, 12 includes a rotating portion 11a, 12a including a stator and a rotor, and an output shaft 11b, 12b for outputting a rotational force obtained by the rotating portion 11a, 12a to the outside. In addition, known wheels can be used as the wheels 13, 14. More specifically, each wheel 13, 14 includes a wheel member 13a, 14a made of metal or plastic, and a tire member 13b, 14b made of rubber with a high friction force attached to the outer periphery of the wheel member 13a, 14a. Note that since the tire members 13b, 14b are consumables, the tire members 13b, 14b can be detached from the wheel members 13a, 14a and replaced as necessary. In the present invention, as illustrated in, for example, FIGS. 3 and 4, the wheel members 13a, 14a of the wheels 13, 14 are directly fixed to the output shafts 11b, 12b of the motors 11, 12. Note that the wheel members 13a, 14a and the output shafts 11b, 12b may be fixed to each other by frictional force generated between them, or a known fixing method such as adhesive or welding may be used. As a result, the rotational forces of the output shafts 11b, 12b are directly transmitted to the wheel members 13a, 14a. In other words, in typical model automobiles and the like, the output shaft of the motor and the wheel members of the wheels are linked through intermediate parts such as gears and shafts; however, in the travel device 1 of the present invention, these intermediate parts are not required.

[0028] In addition, in order to ensure torque, large-diameter rotating portions 11a, 12a (stators and rotors) for motors 11, 12 are demanded, while at the same time, due to restrictions on the width of the lane and the height of the side walls, for example, there is a demand to adopt small-diameter wheels 13, 14. The travel device 1 according to the present invention is basically designed to meet such demands. In particular, by reducing the size of the wheels 13, 14, as shown in FIG. 1 for example, the wheels 13 become less visible to the viewer, giving the viewer the impression that the dome-shaped cover 3 is traveling in the lane. However, in a case in which large diameter motors 11, 12 and small diameter wheels 13, 14 are used at the same time, if the output shafts 11b, 12b of the motors 11, 12 are to be arranged parallel to the ground contact surface G, the wheels 13, 14 will be raised above the ground contact surface G. More specifically, such a problem occurs when the diameters of the tire members 13b, 14b of the wheels 13, 14 are smaller than the diameters of the rotating portions 11a, 12a of the motors 11, 12.

[0029] Therefore, in the travel device 1 of the present invention, even in a case in which the diameters of the tire members 13b, 14b of the wheels 13, 14 are smaller than the diameters of the rotating portions 11a, 12a of the motors 11, 12, the motors 11, 12 are fixed to the chassis 10 at angles so that the tire members 13b, 14b come into contact with the ground contact surface G. That is, as shown in FIG. 3, the motors 11, 12 are fixed to the chassis 10 such that the output shafts 11b, 12b are inclined at angles relative to the ground contact surfaces G of the wheels 13, 14. More specifically, in FIG. 3, the rotation axis of the output shaft 11b of the first motor 11 is indicated by the symbol S1, the rotation axis of the output shaft 12b of the second motor 12 is indicated by the symbol S2, and the ground contact surfaces of the wheels 13, 14 are indicated by the symbol G. In this case, the angles θ1, θ2 between the rotation axes S1, S2 and the ground contact surface G are preferably 10 to 80 degrees, more preferably 30 to 70 degrees, and particularly preferably 45 to 60 degrees. In this way, by fixing the motors 11, 12 to the chassis 10 with the output shafts 11b, 12b inclined relative to the ground contact surface G, the tire members 13b, 14b can be brought into firm contact with the ground contact surface G even when the wheels 13, 14 have a small diameter.

[0030] Note that in FIG. 3, a vertical line to the ground contact surface G is further indicated by the symbol V. Here, the rotation axes S1, S2 of the output shafts 11b, 12b of the motors 11, 12 are also inclined at an angle with respect to the vertical line V. The angles θ3, θ4 between the rotation axes S1, S2 and the vertical line V are preferably from 10 to 80 degrees, more preferably from 20 to 60 degrees, and particularly preferably from 30 to 45 degrees.

[0031] In addition, in a case in which the wheels 13, 14 are directly attached to the motors 11, 12 as described above and the motors 11, 12 are fixed to the chassis 10 at an angle, the wheels 13, 14 come into line contact with the ground surface G. That is, the tire members 13b, 14b of the wheels 13, 14 do not come into surface contact with the ground surface G, but rather come into contact with the ground surface G with one side (the center side of the vehicle body 2) in a raised state. Note that this can also be seen from the side view of the vehicle body 2 illustrated in FIG. 5.

[0032] In addition to the wheels 13, 14 (drive wheels) fixed to the motors 11, 12 described above, the travel device 1 includes a plurality of side rollers 18 that contact the side walls of the lane, and a plurality of driven wheels 19 that contact the travel surface (ground contact surface G) of the lane. These side rollers 18 and driven wheels 19 are not connected to a drive source such as a motor, and are wheels for assisting the travel device 1 in traveling. In the present embodiment, the side rollers 18 are arranged at each of the four corners, front, rear, left and right, of the chassis 10, and the driven wheels 19 are arranged at two locations, left and right, at the front of the chassis 10. Note that the number of side rollers 18 and driven wheels 19 can be increased or decreased depending on the size or the like of the chassis 10. This makes it easier for the travel device 1 to travel along a lane that has been laid in advance. Note that the travel device 1 according to the present embodiment is designed to basically travel straight when traveling on a flat surface without lanes.

[0033] For example, as shown in FIG. 2, the travel device 1 further includes an electronic board 15, a control device 16, and a plurality of light-emitting elements 17. The electronic board 15 is fixed to the chassis 10, and the control device 16 is attached to the electronic board 15. The above-mentioned motors 11, 12 are electrically connected to the control device 16 via the electronic board 15 and are controlled by the control device 16. Similarly, the plurality of light-emitting elements 17 are electrically connected to the control device 16 via the electronic board 15 and are controlled by the control device 16. In this way, the control device 16 is utilized to control the driving states of the motors 11, 12 and the light emission states of the light-emitting elements 17.

[0034] FIG. 6 is a block diagram illustrating a control system centered around the control device 16. In the example illustrated in FIG. 6, the control device 16 includes a processor 16a, a memory 16b, a communication module 16c, a drive control circuit 16d, and a light emission control circuit 16e. An example of the processor 16a is a known CPU or other control circuit. The processor 16a performs predetermined calculation processing in accordance with programs and data stored in the memory 16b, and executes various types of control processes while writing out the calculation results in a working space of the memory 16b. The memory 16b is composed of a volatile memory such as a random access memory (RAM) or a non-volatile memory such as a flash memory, and is used for the calculation processing by the processor 16a. In the present embodiment, the processor 16a reads a program stored in the memory 16b, and performs processing to drive the motors 11, 12 and cause the light-emitting elements 17 to emit light in accordance with the program.

[0035] The communication module 16c is a communication device for wirelessly communicating with an external device. The communication module 16c may be a communication module that communicates wirelessly using known wireless communication standards such as Wi-Fi (registered trademark), Bluetooth (registered trademark), and NFC, other proprietary standards, frequencies such as the sub-GHz band, or P2MP or Mesh communication other than WLAN. For example, the control device 16 communicates with an external server device (not illustrated) via the communication module 16c. In this case, the control device 16 can control the driving state of the motors 11, 12 and the light emission state of each of the light-emitting elements 17 based on instructions and commands received from the external server device. In addition, the control devices 16 of a plurality of travel devices 1 can also communicate with each other via the communication module 16c. In this case, information may be shared among the plurality of travel devices 1 to control the driving states of the motors 11, 12 and the light emission states of the light-emitting elements 17. For example, position information may be shared among a plurality of travel devices 1, and traveling speeds may be adjusted so that the travel devices 1 do not collide with each other on the lane. In addition, for example, position information may be shared among a plurality of travel devices 1, and the light emission states of the light-emitting elements 17 may be changed according to the distance between them. Note that each travel device 1 can use the communication module 16c to identify or estimate its own position information from NFC tags, Bluetooth (registered trademark) beacons, or the like arranged on the lane.

[0036] The drive control circuit 16d is a circuit that supplies electric power from a battery to each of the first motor 11 and the second motor 12 so that the first motor 11 and the second motor 12 operate under specified rotation conditions (rotation speed, rotation direction, and the like) based on control commands from the processor 16a. In addition, by switching the rotation direction of each of the motors 11, 12, the travel device 1 can also be switched between forward and reverse. In addition, the drive control circuit 16d is capable of controlling the first motor 11 and the second motor 12 independently of each other. Moreover, the light emission control circuit 16e is a circuit that supplies electric power from a battery to each light-emitting element 17 so that each light-emitting element 17 emits light under specified light emission conditions (light color, brightness, and the like) based on control commands of the processor 16a. The light emission control circuit 16e is capable of controlling each of the light-emitting elements 17 independently.

[0037] In addition, the travel device 1 includes a battery (not illustrated). The battery may be a primary battery or a secondary battery. However, since repeatedly rechargeable batteries provide higher operational efficiency, it is preferable to use secondary batteries as the batteries. Electric power is supplied from the battery to, for example, the motors 11, 12, the control device 16, and the light-emitting elements 17.

[0038] FIGS. 7A and 7B illustrate examples of control of the vehicle body 2 of the travel device 1. FIG. 7A illustrates a basic example of control of the vehicle body 2. In the example illustrated in FIG. 7A, the vehicle body 2 is controlled to always move straight. More specifically, the travel device 1 according to the present invention can control the left and right motors 11, 12 independently. In order to move the vehicle body 2 straight, it is basically necessary to make the rotation speeds of the left and right motors 11, 12 equal to each other. In this case, ideally the vehicle body 2 will move straight; however, in reality, due to an imbalance in the vehicle body 2 or the like, the vehicle body 2 may move to the left or right. In the example illustrated in FIG. 7A, the rotation speeds of the left and right motors 11, 12 are set equal so that the vehicle body 2 moves straight; however, the vehicle body 2 actually turns left and continues to contact the wall on the left side of the lane. In a case in which the vehicle body 2 continues to contact the side wall of the lane in this manner, there is a concern that the travel efficiency of the vehicle body 2 will decrease and uneven wear will occur in the vehicle body 2 and the tire members 13b, 14b.

[0039] On the other hand, FIG. 7B illustrates an example of improved control of the vehicle body 2. In the example illustrated in FIG. 7B, as in FIG. 7A, a vehicle body 2 is handled that has a tendency to move to the left even when being made to move straight. In this case, in FIG. 7B, the control direction of the vehicle body 2 is changed regularly. More specifically, in FIG. 7B, a state in which the vehicle body 2 moves along the lane is divided into nine frames. In the first frame, the vehicle body 2 is controlled to move straight. At this time, the rotation speeds of the first motor 11 and the second motor 12 become equal. However, due to a tendency of the vehicle body 2, the vehicle body 2 actually moves to the left. Next, in the second frame and third frame, the vehicle body 2 is controlled so as to move toward the right side. At this time, the rotation speed of the first motor 11 provided on the right side of the chassis 10 is made slower than the rotation speed of the second motor 12 provided on the left side of the chassis 10 (it is possible to stop only the first motor 11). Next, in the fourth frame, the rotation speeds of the first motor 11 and the second motor 12 are again made equal, thereby controlling the vehicle body 2 to move straight. When attention is paid to the fourth frame, it can be seen that the vehicle body 2 is not in contact with either side wall of the lane. This is the result of controlling the vehicle body 2, which has a tendency to move toward the left, to move toward the right, thereby canceling out the forces moving toward the left and the forces moving toward the right.

[0040] Next, in the fifth frame and sixth frame, the vehicle body 2 is controlled so as to move toward the left side. At this time, the rotation speed of the first motor 11 provided on the right side of the chassis 10 is made faster than the rotation speed of the second motor 12 provided on the left side of the chassis 10 (it is possible to stop only the second motor 12). In this case, the vehicle body 2, which has a tendency to go left, will move further toward the left side; however, since the lane has a side wall, the vehicle 2 continues to move along the lane. Next, in the seventh frame, the rotation speeds of the first motor 11 and the second motor 12 are again made equal, thereby controlling the vehicle body 2 to move straight. Next, in the eighth frame and ninth frame, the vehicle body 2 is controlled to move toward the right side again, similarly to the second and third frames. As a result, when attention is paid to the ninth frame, it can be seen that the vehicle body 2 is not in contact with either side wall of the lane.

[0041] As described above, by regularly switching between high and low rotation speeds of the first motor 11 and the second motor 12, it is possible to create a period during which the vehicle body 2 travels straight without touching the side wall of the lane. As a result, the travel efficiency of the vehicle body 2 can be improved compared to the basic control example shown in FIG. 7A.

[0042] Note that in the example illustrated in FIG. 7B, it is unclear whether the vehicle body 2 has a tendency to move toward the left or toward the right, and thus control toward the left and control toward the right are performed regularly. However, when the tendency of the vehicle body 2 is known in advance, it is possible to continue only one of control toward the left and control toward the right. In addition, in the example illustrated in FIG. 7B, the control toward the left and the control toward the right are performed regularly, but these controls may be performed completely randomly. Even in a case of random control, when the probability of control toward the left and control toward the right occurring is approximately equal, the results will be roughly the same as when these controls are performed regularly.

[0043] In the above description of the present invention, embodiments of the present invention have been described with reference to the drawings in order to express the contents of the present invention. However, the present invention is not limited to the above-described embodiments, and includes modifications and improvements that are obvious to those skilled in the art based on the matters described in this specification.REFERENCE SIGNS LIST1 . . . Travel device2 . . . Vehicle body3 . . . Cover10 . . . Chassis11 . . . First motor11a . . . Rotating portion11b . . . Output shaft12 . . . Second motor12a . . . Rotating portion12b . . . Output shaft13 . . . First wheel13a . . . Wheel member13b . . . Tire member14 . . . Second wheel14a . . . Wheel member14b . . . Tire member15 . . . Electronic board16 . . . Control device16a . . . Processor16b . . . Memory16c . . . Communication module16d . . . Drive control circuit16e . . . Light emission control circuit17 . . . Light-emitting element18 . . . Side roller19 . . . Driven wheel

Claims

1. A travel device comprising:a chassis;a first motor and a second motor mounted on the chassis, wherein the first motor and the second motor include a rotating portion and an output shaft for externally outputting a rotational force obtained by the rotating portion; anda first wheel and a second wheel attached to the output shaft of the first motor and the output shaft of the second motor, respectively; whereineach of the first motor and the second motor is mounted on the chassis with the output shaft inclined at an angle with respect to a ground contact surface of the first wheel and the second wheel,each of the first wheel and the second wheel includes a wheel member directly attached to the output shaft, and a tire member attached to an outer periphery of the wheel member, anda diameter of each of the tire members of the first wheel and the second wheel is smaller than a diameter of the rotating portion of the first motor and the second motor.

2. The travel device according to claim 1, whereinthe tire member is in line contact with the ground contact surface.

3. The travel device according to claim 1, whereinno gear is interposed between the first motor and the first wheel, and no gear is interposed between the second motor and the second wheel.

4. The travel device according to claim 1, further comprisinga control device that independently controls the first motor and the second motor.

5. The travel device according to claim 4, whereinthe control device regularly or randomly switches between two or more states including a state in which a rotation speed of the first motor is faster than a rotation speed of the second motor, and a state in which a rotation speed of the second motor is faster than a rotation speed of the first motor.

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