Rocker bogie car

Abstract

To suppress cargo collapse of articles loaded on a rear body even in the case of traveling on an off-road and steps.SOLUTION: A rocker bogie car 1 includes: a bogie link 20 pivotally supporting a front wheel 11 and an intermediate wheel 12, and connecting them; a rocker link body 30 having a rocker link 32 pivotally supporting an intermediate part 21c between the front wheel 11 and the intermediate wheel 12 of the bogie link 20, and a rear wheel 13, and connecting them; a rear body support mechanism 42 for connecting the rocker link body 30 and a rear body 41, and supporting the rear body 41; and a control section. The rear body support mechanism 42 includes a front side support mechanism 42A and a rear side support mechanism 42B disposed at a front side and a rear side of the rocker link body 30. Any one of or both of the front side support mechanism 42A and the rear side support mechanism 42B include a linear motion type actuator 43 disposed so as to make a distance between the rocker link body 30 and the rear body 41 adjustable. The control section controls by expanding and contracting the linear motion type actuator 43 so as to make the rear body 41 horizontal.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a rocker bogie vehicle.

Background Art

[0002] In a mobile device that travels by wheels, the traveling performance in cases such as traveling on uneven ground or crossing a step is generally not high. Regarding such mobile devices, technological development has been carried out to improve the traveling performance on uneven ground and steps. Particularly, when transporting an article using such a mobile device, if the mobile device travels on uneven ground or a step, the loading platform may tilt, and the transported goods may collapse, fall, or drop. In contrast, Patent Document 1 discloses a configuration including a loading platform, at least four legs that support the loading platform, a horizontal holding mechanism that maintains the horizontal state of the loading platform, and a control mechanism that controls its own center of gravity position to be able to move up and down on a step or slope and controls the posture of the legs. By the way, as a mobile device that travels by wheels, there is a rocker bogie vehicle having a structure with three pairs of driving wheels by a rocker link and a bogie link, which has high traveling performance on uneven ground. Even when traveling on uneven ground or steps with such a rocker bogie vehicle, it is desired to suppress the collapse of the transported goods and further improve the traveling performance.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The problem to be solved by the present invention is to provide a rocker bogie vehicle that can suppress the collapse of the articles loaded on the loading platform and improve the traveling performance even when traveling on uneven ground or steps. [Means for solving the problem]

[0005] To solve the above problems, the present invention employs the following means. In other words, the rocker bogie vehicle of the present invention is a rocker bogie vehicle for transporting goods loaded on a cargo bed, wherein each of the front wheels, middle wheels, and rear wheels is provided in pairs on the left and right sides, and the vehicle comprises a bogie link that pivotally supports and connects the front wheels and the middle wheels, a rocker link body having a rocker link that pivotally supports and connects the intermediate portion of the bogie link between the front wheels and the middle wheels and the rear wheels, a cargo bed support mechanism that connects the rocker link body to the cargo bed and supports the cargo bed, and a control unit, wherein the cargo bed support mechanism comprises a front support mechanism and a rear support mechanism provided on the front and rear sides of the rocker link body, respectively, and either or both of the front support mechanism and the rear support mechanism are provided with a linear actuator that is provided to adjust the distance between the rocker link body and the cargo bed, and the control unit extends and retracts the linear actuator to control the cargo bed so that it becomes horizontal. With this configuration, the rocker bogie car can travel on uneven terrain by having a bogie link that supports the front and middle wheels and connects them, and a rocker link that supports the intermediate section between the front and middle wheels of the bogie link and the rear wheels and connects them. In particular, when traveling over a step, for example, when the rocker bogie car is located on a first ground surface and moves vertically from the first ground surface to a second ground surface that is higher than the first ground surface and located beyond the step, first the middle and rear wheels are brought into contact with the first ground surface, and the bogie link is rotated around the intermediate section supported by the rocker link to raise the front wheels higher than the middle and rear wheels, and then the car moves forward in this state to bring the front wheels into contact with the second ground surface. Next, the bogie link is rotated in the opposite direction to raise the middle wheels to the same height as the front wheels, and then the car moves forward further in this state to bring the middle wheels into contact with the second ground surface in addition to the front wheels. Then, the front and middle wheels support the body and propel it forward, while the rear wheels kick up against a vertical surface, lifting the rear wheels to a second ground surface. This allows the rocker bogie car to climb over obstacles. It is also possible to descend obstacles using a similar procedure, and in this way the rocker bogie car can overcome obstacles and continue to travel. In this way, when a rocker bogie truck travels over uneven terrain or steps, it is necessary to displace one of the front, middle, or rear wheels to a position at a different height than the others. As a result, both the bogie links and rocker links change their angle with respect to the horizontal plane, and the cargo bed, which is supported by the cargo bed support mechanism on the rocker link body, also tends to tilt with respect to the horizontal plane. The cargo bed support mechanism comprises a front support mechanism and a rear support mechanism, respectively, provided on the front and rear sides of the rocker link body. One or both of the front and rear support mechanisms are equipped with linear actuators that allow adjustment of the distance between the rocker link body and the cargo bed, and the control unit extends and retracts the linear actuators to control the cargo bed so that it is horizontal. For this reason, when the linear actuator is provided on the front support mechanism, the linear actuator is retracted when the rocker link body tilts so that the front side is lifted relative to the rear side, and the linear actuator is extended when the rocker link body tilts so that the front side is lowered relative to the rear side, thereby controlling the cargo bed to be horizontal. Furthermore, if a linear actuator is provided on the rear support mechanism, the linear actuator can be extended when the rocker link body tilts so that the front side lifts relative to the rear side, and retracted when the rocker link body tilts so that the front side lowers relative to the rear side, thereby controlling the cargo bed to be level. Alternatively, if linear actuators are provided on both the front and rear support mechanisms, the cargo bed can be controlled to be level by either of the above actions, or by a combination of the above actions. Furthermore, as described above, since the cargo bed is controlled to remain horizontal, driving stability is improved even when traveling on uneven terrain or over bumps, thus enhancing driving performance. In this way, even when driving on uneven terrain or over bumps, the cargo bed is controlled to remain level, which in turn suppresses the shifting of goods loaded on the cargo bed and improves driving performance.

[0006] In one embodiment of the present invention, the linear actuator is provided on both the front support mechanism and the rear support mechanism, and each of the front support mechanism and the rear support mechanism is connected to the rocker link body via a rotational support portion so as to be rotatable in the front-rear direction relative to the rocker link body, and the control unit controls the rotation of the rotational support portion relative to the rocker link body while extending and retracting the linear actuator to control the loading platform to be horizontal. With this configuration, linear actuators are provided on both the front and rear support mechanisms, and each of the front and rear support mechanisms is connected to the rocker link body via a rotation support section so that it can rotate in the front-rear direction relative to the rocker link body. Therefore, each linear actuator can be rotated while extending and contracting independently. As a result, even when traveling over uneven terrain with larger steps or vertical movement, the control unit can flexibly control the loading platform to keep it level. Furthermore, when the rocker link body of a rocker bogie vehicle tilts significantly, causing the linear actuator to extend or retract significantly, simply extending or retracting the linear actuator alone may hinder the extension or retraction due to the rigidity of the cargo bed, as the distance between the ends of the front and rear support mechanisms connected to the cargo bed changes. In this case, the front and rear support mechanisms are connected to the rocker link body via a rotational support section so that they can rotate in the front-rear direction relative to the rocker link body. The control unit controls the rotation of the rotational support section relative to the rocker link body while extending or retracting the linear actuator, thereby controlling the cargo bed to remain horizontal. Therefore, for example, while extending or retracting the linear actuator, it becomes possible to rotate the front and rear support mechanisms by controlling the rotation of the rotational support section so that the distance between the ends of the front and rear support mechanisms on the cargo bed side remains constant, thereby suppressing the restriction of the extension and retraction operation of the linear actuator.

[0007] In one embodiment of the present invention, the front support mechanism and the rear support mechanism are connected to the cargo bed via an angle adjustment mechanism that allows the angle with respect to the cargo bed to be adjusted at least in the front-rear direction. In this configuration, when the rocker link body of the rocker bogie car is tilted and the linear actuators of the front and rear support mechanisms are extended or retracted so that the cargo bed becomes horizontal, the angle of the front and rear support mechanisms relative to the cargo bed may change. However, in the above configuration, each of the front and rear support mechanisms is connected to the cargo bed via an angle adjustment mechanism that allows adjustment of the angle relative to the cargo bed at least in the longitudinal direction, so that it can follow the change in the angle of the front and rear support mechanisms relative to the cargo bed.

[0008] In one embodiment of the present invention, the control unit controls the movement of the cargo bed backward by rotating the rotational support portions of both the front support mechanism and the rear support mechanism toward the rear relative to the rocker link body when raising or lowering the front wheel. With this configuration, for example, when raising the front wheels to go up a step, the rotational support parts of both the front and rear support mechanisms are rotated toward the rear relative to the rocker link body, controlling the movement of the cargo bed toward the rear. As a result, the center of gravity of the cargo bed shifts toward the rear, reducing the load acting on the front wheels and making it easier to raise the front wheels. Furthermore, when descending a step, if the front wheels are lowered, the rotational support parts of both the front and rear support mechanisms are rotated towards the rear relative to the rocker link body, controlling the movement of the loading platform backward. As a result, the center of gravity of the loading platform shifts backward, preventing the rocker bogie vehicle from tipping forward due to the load and falling down the step while the front wheels are not supported by the ground surface and are floating in the air until they make contact with the ground surface beyond the step.

[0009] In one embodiment of the present invention, when the rear wheel is raised, the control unit rotates the rotational support portions of both the front support mechanism and the rear support mechanism toward the front relative to the rocker link body, thereby controlling the movement of the cargo bed forward. With this configuration, for example, when climbing a step, the front and middle wheels first make contact with the ground surface located beyond the step (upper step), and with the vehicle body supported by the front and middle wheels, the rear wheels are raised to the same height as the front and middle wheels. When raising the rear wheels, the rotational support parts of both the front and rear support mechanisms are rotated forward relative to the rocker link body, controlling the movement of the loading platform forward. As a result, the center of gravity of the loading platform shifts forward, reducing the load acting on the rear wheels, making it easier to raise the rear wheels, and preventing the rocker bogie vehicle from tipping backward and falling down the step due to the load.

[0010] In one embodiment of the present invention, each of the front support mechanism and the rear support mechanism is provided in pairs on the left and right sides. This configuration prevents the cargo bed from tilting laterally and allows for stable support of the cargo bed. Furthermore, even when the rocker link body tilts laterally, for example, so that the right side of the rocker link body rises relative to the left side, the loading platform can be controlled to remain horizontal by, for example, contracting the front and rear support mechanisms on the right side, or extending the front and rear support mechanisms on the left side. Similarly, even when the right side of the rocker link body descends relative to the left side, the loading platform can be controlled to remain horizontal by, for example, extending the front and rear support mechanisms on the right side, or contracting the front and rear support mechanisms on the left side. In this way, the loading platform can be controlled to remain horizontal not only in the longitudinal direction but also when the rocker link body tilts laterally.

[0011] In one aspect of the present invention, the locker bogie vehicle of the present invention further includes an attitude sensor capable of measuring the attitude of the loading platform, and the control unit controls the rotation of the rotary support portion while expanding and contracting the linear actuator based on the measurement result of the attitude sensor so as to control the loading platform to be horizontal. According to such a configuration, it is possible to realize a locker bogie vehicle that can suppress the collapse of the loads on the loading platform and improve the running performance even when traveling on uneven ground or steps.

Effects of the Invention

[0012] According to the present invention, even when traveling on uneven ground or steps, it is possible to suppress the collapse of the loads on the loading platform and improve the running performance.

Brief Description of the Drawings

[0013] [Figure 1] It is a side view showing the configuration of a locker bogie vehicle according to an embodiment of the present invention. [Figure 2] It is a plan view showing the configuration of the vehicle body portion of the locker bogie vehicle. [Figure 3] It is a block diagram showing the functional configuration of the control unit of the locker bogie vehicle in the present embodiment. [Figure 4] It is a flowchart showing the running operation of the locker bogie vehicle according to the present embodiment. [Figure 5] It is a view showing a state in which, when the locker bogie vehicle climbs a step, the front wheels are raised and grounded on a second ground surface at the tip of the step. [Figure 6] It is a view showing a state in which, when the locker bogie vehicle climbs a step, the middle wheels are raised to the height of the second ground surface at the tip of the step. [[ID=​​​​​​​This is a diagram showing the state of the rocker bogie vehicle when climbing a step. [Figure 10] This is a diagram showing the state of the rocker bogie vehicle when descending a step, with the front wheels being lowered while contacting the vertical surface at the tip of the step. [Figure 11] This is a diagram showing the state of the rocker bogie vehicle when descending a step, with the front wheels placed on the first ground surface at the tip of the step. [Figure 12] This is a diagram showing the state of the rocker bogie vehicle when descending a step, with the middle wheels being lowered towards the second ground surface at the tip of the step. [Figure 13] This is a diagram showing the state of the rocker bogie vehicle when descending a step, with the middle wheels touching the second ground surface.

Embodiments for Carrying Out the Invention

[0014] Hereinafter, with reference to the accompanying drawings, embodiments for carrying out the rocker bogie vehicle according to the present invention will be described based on the drawings. A side view showing the configuration of the rocker bogie vehicle according to an embodiment of the present invention is shown in FIG. 1. FIG. 2 is a plan view showing the configuration of the vehicle body portion of the rocker bogie vehicle. The rocker bogie vehicle 1 includes a vehicle body portion 10, a loading platform portion 40, and a control portion 60 (see FIG. 3). The vehicle body portion 10 includes bogie links 20, a rocker link body 30, front wheels 11, middle wheels 12, and rear wheels 13. In the rocker bogie vehicle 1, a pair of each of the front wheels 11, middle wheels 12, and rear wheels 13 are provided on the left and right, and carry articles loaded on the loading platform 41.

[0015] A pair of bogie links 20 are provided on the left and right, which are both sides in the vehicle width direction of the rocker bogie vehicle 1. The pair of bogie links 20 have a right bogie link 20R provided on the right side and a left bogie link 20L provided on the left side. The right bogie link 20R and the left bogie link 20L have a bilaterally symmetric configuration. In the following description, unless it is necessary to distinguish between the right bogie link 20R and the left bogie link 20L, each of the right bogie link 20R and the left bogie link 20L is simply referred to as the bogie link 20. The bogie link 20 pivotally supports the front wheel 11 and the middle wheel 12, respectively, so as to be rotatable around an axis extending in the left-right direction. The bogie link 20 integrally includes an arm 21 extending in the front-rear direction of the vehicle body 10, and front legs 23 and middle legs 24 extending downward from each of the front and rear ends of the arm 21. The front wheel 11 is rotatably supported by the front legs 23 located at the front end of the bogie link 20. The middle wheel 12 is rotatably supported by the middle legs 24 located at the rear end of the bogie link 20. In this way, the bogie link 20 pivotally supports the front wheel 11 and the middle wheel 12, and connects them.

[0016] The rocker link assembly 30 comprises a main body 31 and a pair of rocker links 32. The main body 31 is the main body of the rocker bogie car 1. For example, the control unit 60, which will be described later, can be installed on this main body 31. The main body 31 is positioned between a pair of rocker links 32 in the left-right direction. When viewed from above, the main body 31 is formed in a rectangular shape, for example.

[0017] A pair of rocker links 32 are provided on the left and right sides of the rocker bogie car 1. The pair of rocker links 32 consists of a right rocker link 32R provided on the right side and a left rocker link 32L provided on the left side. The right rocker link 32R and the left rocker link 32L are configured symmetrically. The rocker link 32 integrally comprises a link arm 33 extending in the front-rear direction and a rear leg portion 34 extending downward from the rear end of the link arm 33. The front end of the link arm 33 is pivotally supported on the intermediate portion 21c of the arm 21 of the bogie link 20 in the front-rear direction, via a drive shaft 35 extending in the left-right direction, so as to be rotatable around the central axis of the drive shaft 35. This allows the link arm 33 to swing relative to the bogie link 20 around the drive shaft 35. The rear wheel 13 is rotatably supported at the lower end of the rear leg portion 34. In this way, the rocker link 32 pivotally supports and connects the intermediate portion 21c between the front wheel 11 and the middle wheel 12 of the bogie link 20 and the rear wheel 13.

[0018] As will be explained later, the rocker link 32 tilts when the rocker bogie car 1 travels over a step or other obstacle. In this embodiment, the rocker link body 30 is provided integrally with the rocker link 32 so as to be unable to move or be displaced relative to it, and is a part of the rocker bogie car 1 that tilts together with the rocker link 32, in the same way as the rocker link 32. Therefore, when the rocker link body 30 includes the main body 31 as described above, the right rocker link 32R and the left rocker link 32L are fixed integrally with the main body 31, and when the rocker link 32 is tilted, the main body 31 tilts together with the rocker link 32. In Figure 1, the rocker link 32 is shown as a separate part from the main body 31, but the link arm 33 and the main body 31 may be integrated, and the main body 31 may directly pivotally support the bogie link 20 by the drive shaft 35, with the rear leg portion 34 extending downward from the main body. The cargo bed support mechanism, which will be described later, is connected to the rocker link body 30, but in this case, the cargo bed support mechanism may be connected to the main body 31. In contrast, in a rocker bogie vehicle, it is also conceivable that the right rocker link 32R and the left rocker link 32L are pivotally supported on the main body 31 and are rotatably mounted relative to the main body 31. In this case, since the main body 31 is not included in the rocker link body 30, the cargo bed support mechanism, which will be described later, is connected to some part of the rocker link body 30, not to the main body 31. In the following description, unless it is necessary to distinguish between the right rocker link 32R and the left rocker link 32L, the right rocker link 32R and the left rocker link 32L will each be simply referred to as rocker link 32.

[0019] The bogie links 20 (right bogie link 20R, left bogie link 20L) are driven by a bogie link control motor 37 to rotate relative to the rocker links 32 (right rocker link 32R, left rocker link 32L) around the central axis of the drive shaft 35. In other words, the bogie links 20 are dynamically rotatable relative to the rocker links 32 by the bogie link control motor 37. The relative angle between the bogie links 20 and the rocker links 32 around the drive shaft 35 is controllable. Furthermore, by turning off the drive by the bogie link control motor 37, the bogie links 20 and the rocker links 32 can rotate freely around the drive shaft 35. Such a bogie link control motor 37 can be realized by an actuator that can freely control the rotational driving force, such as a torque motor or a harmonic drive (registered trademark). An angle sensor (not shown) is provided on the rocker link 32. The angle sensor is attached to the drive shaft 35 and detects the relative rotation angle of the rocker link 32 with respect to the bogie link 20. The information on the relative rotation angle of the rocker link 32 with respect to the bogie link 20, as detected by the angle sensor, is output to the control unit 60, which will be described later.

[0020] The front wheels 11 are provided in pairs on the left and right sides at the front end of the rocker bogie car 1. The pair of front wheels 11 consists of a right front wheel 11R provided on the right side and a left front wheel 11L provided on the left side. The intermediate wheels 12 are provided in pairs on the left and right sides in the middle section of the rocker bogie car 1 in the longitudinal direction. The pair of intermediate wheels 12 consists of a right intermediate wheel 12R provided on the right side and a left intermediate wheel 12L provided on the left side. The rear wheels 13 are provided in pairs on the left and right sides at the rear end of the rocker bogie car 1. The pair of rear wheels 13 consists of a right rear wheel 13R provided on the right side and a left rear wheel 13L provided on the left side.

[0021] Each of the front wheels 11 (right front wheel 11R, left front wheel 11L) and the rear wheels 13 (right rear wheel 13R, right rear wheel 13R) is a Mecanum wheel (registered trademark). Each of the front wheels 11 and the rear wheels 13 has a main wheel and a plurality of freewheels provided on the outer circumference of the main wheel, which are rotatably supported at a 45° inclination with respect to the axle and are arranged in the circumferential direction. The intermediate wheels 12 (right intermediate wheel 12R, left intermediate wheel 12L) are omniwheels (registered trademark). The intermediate wheel 12 comprises a main wheel and a plurality of freewheels provided on the outer circumference of the main wheel, supported so as to be rotatable at a 90° angle to the axle, and arranged in the circumferential direction.

[0022] The main wheel of the right front wheel 11R is driven by motor 14R. The main wheel of the left front wheel 11L is driven by motor 14L. The main wheel of the right middle wheel 12R is driven by motor 15R. The main wheel of the left middle wheel 12L is driven by motor 15L. The main wheel of the right rear wheel 13R is driven by motor 16R. The main wheel of the left rear wheel 13L is driven by motor 16L. These motors 14R, 14L, 15R, 15L, 16R, and 16L can each be controlled independently. In other words, each of the front wheels 11, middle wheels 12, and rear wheels 13 can each be driven and controlled independently. The vehicle body 10 controls each of the front wheels 11 (right front wheel 11R, left front wheel 11L), middle wheels 12 (right middle wheel 12R, left middle wheel 12L), and rear wheels 13 (right rear wheel 13R, right rear wheel 13R) to rotate in either the forward or reverse direction. This enables the vehicle body 10 to move forward, backward, sideways, diagonally, or perform spin turns.

[0023] The rocker bogie vehicle 1 is equipped with an obstacle detection unit 18 to control the movement of the vehicle body 10. The obstacle detection unit 18 is provided, for example, on the loading platform 41, which will be described later. The obstacle detection unit 18 is not limited to the loading platform 41, but may also be provided in other locations, such as the main body 31 of the vehicle body 10. The obstacle detection unit 18 detects obstacles, including steps and slopes, located in front of the vehicle body 10 in the direction of travel, and measures the distance to the detected obstacle. The obstacle detection unit 18 is, for example, a 3DLiDAR (Light Detection And Ranging or Laser Imaging Detection And Ranging). The obstacle detection unit 18 is not limited to a 3DLiDAR; for example, it may be a depth sensor that acquires distance information by ToF (Time of Flight), an ultrasonic sensor, an infrared sensor, radar, etc. Alternatively, the obstacle detection unit 18 may have a CCD (Charge Coupled Device) camera and acquire two-dimensional images and depth data using near-infrared IR. The obstacle detection unit 18 outputs distance information to the detected obstacle to the control unit 60, which will be described later.

[0024] The cargo bed section 40 includes a cargo bed 41, a cargo bed support mechanism 42, and a posture sensor 50. The cargo bed 41 is positioned above the vehicle body 10, spaced apart from the vehicle body 10. The cargo bed 41 is, for example, rectangular when viewed from above. The shape of the cargo bed 41 is not limited to a rectangle, and may be any other shape as appropriate. The upper surface 41t of the cargo bed 41 is a flat surface on which goods can be placed.

[0025] The cargo bed support mechanism 42 connects the rocker link body 30 and the cargo bed 41, and supports the cargo bed 41 from below. The cargo bed support mechanism 42 includes a front support mechanism 42A provided on the front side of the rocker link body 30 and a rear support mechanism 42B provided on the rear side of the rocker link body 30. In this embodiment, each of the front support mechanism 42A and the rear support mechanism 42B is provided in pairs on the left and right sides. As will be explained later, the cargo bed support mechanism 42 is controlled by the control unit 60 (more specifically, the cargo bed horizontal control unit 62, which will be explained later) so that when the rocker link body 30 (rocker link 32) is tilted, the cargo bed 41 becomes horizontal in response to the tilt of the rocker link body 30. For this reason, when the rocker link 32 is integrally fixed to the main body 31 as in this embodiment, the cargo bed support mechanism 42 may be provided on the main body 31 as shown in Figure 2. When the rocker link 32 is pivotally supported on the main body 31, it is preferable that the cargo bed support mechanism 42 be provided on the rocker link 32, for example, with respect to the link arm 33. The front support mechanism 42A and the rear support mechanism 42B each include a linear actuator 43, a rotational support section 44, and an angle adjustment mechanism 45, respectively.

[0026] The linear actuator 43 extends vertically between the rocker link body 30 and the loading platform 41. The linear actuator 43 is extendable and retractable in the vertical direction, and is designed to allow adjustment of the distance between the rocker link body 30 and the loading platform 41. Here, the linear actuator 43 of the front support mechanism 42A and the linear actuator 43 of the rear support mechanism 42B are controlled by the control unit 60 (bed horizontal control unit 62) to extend and retract independently. In addition, in the pair of left and right bed support mechanisms 42, the front support mechanism 42A and rear support mechanism 42B located on the right side and the front support mechanism 42A and rear support mechanism 42B located on the left side are controlled by the control unit 60 to extend and retract independently.

[0027] The rotation support section 44 connects the lower end of the linear actuator 43 to the rocker link body 30 in each of the front support mechanism 42A and the rear support mechanism 42B so that it can rotate relative to the rocker link body 30 in the front-rear direction. The rotation support section 44 has a rotation shaft 44s that extends in the left-right direction, and the lower end of the linear actuator 43 is connected to it so as to be rotatable around the rotation shaft 44s. The rotation support section 44 is capable of swinging the linear actuator 43 in the front-rear direction via the rotation shaft 44s. Here, the rotational support section 44 of the front support mechanism 42A and the rotational support section 44 of the rear support mechanism 42B are controlled by the control unit 60 (bed horizontal control unit 62) to rotate independently. In addition, in the pair of left and right bed support mechanisms 42, the rotational support section 44 located on the right side and the rotational support section 44 located on the left side are controlled by the control unit 60 to rotate independently.

[0028] The angle adjustment mechanism 45 is provided between the upper end of the linear actuator 43 and the loading platform 41. The angle adjustment mechanism 45 connects the linear actuator 43 to the loading platform 41 so that the angle of the linear actuator 43 relative to the loading platform 41 can be adjusted at least in the front-rear direction. In this embodiment, the angle adjustment mechanism 45 is a ball joint that allows the angle of the linear actuator 43 relative to the loading platform 41 to be adjusted in any direction. The angle adjustment mechanism 45 may also be a device that rotatably connects the upper end of the linear actuator 43 and the loading platform 41 around an axis extending in the left-right direction.

[0029] The attitude sensor 50 can measure the attitude of the cargo bed 41. In this embodiment, the attitude sensor 50 includes, for example, an acceleration sensor to detect the forward and backward movement of the cargo bed 41, a gyro sensor to detect the rotational movement of the cargo bed 41, and a position sensor to detect the position of the cargo bed 41, so that it can measure the horizontal state of the cargo bed 41, for example, the upper surface 41t of the cargo bed 41. The attitude sensor 50 outputs the measurement results to the control unit 60.

[0030] Figure 3 is a block diagram showing the functional configuration of the control unit of the rocker bogie car in this embodiment. The control unit 60 controls the operation of the rocker bogie vehicle 1 based on a preset program. As shown in Figure 3, the control unit 60 functionally includes a travel control unit 61 and a cargo bed horizontal control unit 62.

[0031] The driving control unit 61 controls the driving motion of the vehicle body 10. The driving control unit 61 controls motors 14R, 14L, 15R, 15L, 16R, and 16L to rotate the front wheels 11, middle wheels 12, and rear wheels 13, thereby allowing the vehicle body 10 to move under its own power. When the obstacle detection unit 18 detects a step ahead in the direction of travel during driving, the driving control unit 61 controls the bogie link control motor 37 to cause the bogie link 20 to swing relative to the rocker link 32, thereby allowing the vehicle body 10 to overcome the step.

[0032] The cargo bed horizontal control unit 62 controls the operation of the linear actuator 43 and the rotary support unit 44 of the cargo bed support mechanism 42 so that the upper surface 41t of the cargo bed 41 remains horizontal, based on the attitude of the cargo bed 41 detected by the attitude sensor 50. In addition, the linear actuator 43 and the rotary support unit 44 of the cargo bed support mechanism 42 can be operated to control the movement of the center of gravity in order to stably traverse steps.

[0033] Figure 4 is a flowchart showing the running operation of the rocker bogie car 1 according to this embodiment. When the rocker bogie car 1 starts moving, the control unit 60 repeatedly performs the following processes until the rocker bogie car 1 arrives at a preset target value. First, the driving control unit 61 controls the motors 14R, 14L, 15R, 15L, 16R, and 16L to move the vehicle body 10 along a preset path toward the target position (step S1). The driving control unit 61 determines, at predetermined time intervals, whether or not there is a step in front of the vehicle body 10 in the direction of travel, based on the information detected by the obstacle detection unit 18 (step S2). As a result, if there is no step ahead in the direction of travel, the vehicle returns to step S1 and continues driving along the path. On the other hand, if it is determined in step S2 that there is a step ahead in the direction of travel, the driving control unit 61 controls the bogie link control motor 37 to cause the bogie link 20 to swing relative to the rocker link 32, thereby allowing the vehicle body 10 to overcome the step (step S3). Furthermore, if it is determined in step S2 that there is a step ahead in the direction of travel, the cargo bed horizontal control unit 62 controls the operation of the linear actuator 43 and the rotary support unit 44 of the cargo bed support mechanism 42 so that the upper surface 41t of the cargo bed 41 remains horizontal, based on the attitude of the cargo bed 41 detected by the attitude sensor 50 (step S4).

[0034] The following will explain, with specific examples, the running operation of the rocker bogie vehicle 1, which is realized by the control unit 60 executing the process according to the flowchart described above. In the following explanation, when it is stated that the control unit 60 controls the vehicle, it means that either the running control unit 61 or the cargo bed horizontal control unit 62 of the control unit 60 is performing the control according to its role. As shown in Figure 1, when the rocker bogie car 1 travels on a level first ground surface F1 without any steps, the car body 10 has all of its front wheels 11, middle wheels 12, and rear wheels 13 in contact with the level first ground surface F1. In this state, the control unit 60 controls the motors 14R, 14L, 15R, 15L, 16R, and 16L to rotate the front wheels 11, middle wheels 12, and rear wheels 13, thereby causing the car body 10 to travel on the first ground surface F1 along a preset path.

[0035] Figure 5 shows a rocker bogie vehicle ascending a step, with the front wheels raised and in contact with the second ground surface beyond the step. If there is a step D1 with a vertical surface Fv rising upward from a first ground surface F1 in front of the rocker bogie car 1 in the direction of travel, and the area beyond step D1 is a horizontal second ground surface F2, the rocker bogie car 1 first raises its front wheels 11 onto the second ground surface F2 with the middle wheels 12 and rear wheels 13 in contact with the first ground surface F1. To do this, the front wheels 11 first abut against the vertical surface Fv of step D1. In this state, the front wheels 11 are rotated, and the frictional force generated between the front wheels 11 and the vertical surface Fv drives the front wheels 11 to kick up the vertical surface Fv. While moving the front wheels 11 upward along the vertical surface Fv, the bogie link control motor 37 rotates the bogie link 20 around the intermediate part 21c, which is pivotally supported by the rocker link 32, so that the front wheels 11 rise. This lifts the front wheels 11 off the first ground surface F1 and raises them to the second ground surface F2, which is higher than the middle wheels 12 and rear wheels 13. Then, the middle wheels 12 and rear wheels 13 are driven forward, causing the vehicle body 10 to move forward and the front wheels 11 to make contact with the second ground surface F2 located beyond the step D1.

[0036] When the front wheels 11 are lifted in this manner, the front side of the rocker link body 30 lifts up and tilts diagonally downwards from front to rear. Consequently, the cargo bed 41 also attempts to tilt diagonally in a similar manner. The control unit 60 measures this change in the posture of the cargo bed 41 with the posture sensor 50 and drives the linear actuator 43 of the front support mechanism 42A and the linear actuator 43 of the rear support mechanism 42B to extend or retract in accordance with the tilting movement of the rocker link body 30, so that the cargo bed 41 remains horizontal. Specifically, the linear actuator 43 of the front support mechanism 42A is retracted, for example, so that the linear actuator 43 of the front support mechanism 42A becomes shorter than the linear actuator 43 of the rear support mechanism 42B. At this time, the linear actuator 43 of the rear support mechanism 42B may be extended. The operation of the linear actuator 43 causes a change in the angle between the linear actuator 43 and the cargo bed 41. This change in angle is absorbed by the angle adjustment mechanism 45.

[0037] With the rotating support section 44 not rotating, extending or retracting either or both of the linear actuators 43 of the front support mechanism 42A and the rear support mechanism 42B changes the length of the linear actuators 43 of the front support mechanism 42A and the rear support mechanism 42B. At the ends (upper ends) of the linear actuators 43 on the cargo bed 41 side, the position of the upper ends is displaced so that the distance between the upper ends changes. Basically, such displacement is suppressed by the rigidity of the cargo bed 41, thus limiting the extension and retraction movement of the linear actuators 43. In this embodiment, a ball joint is used as the angle adjustment mechanism 45. Small changes in the distance between the ends of the front support mechanism 42A and the rear support mechanism 42B are absorbed by this ball joint.

[0038] Figure 6 shows a rocker bogie vehicle ascending a step, with the middle wheel raised to the height of the second ground surface beyond the step. Next, as shown in Figure 6, the bogie link control motor 37 rotates the bogie link 20 around the intermediate section 21c, which is pivotally supported by the rocker link 32, in the opposite direction to when the front wheels 11 were raised. With the front wheels 11 still in contact with the second ground surface F2 and the rear wheels 13 in contact with the first ground surface F1, the middle wheels 12 are raised to the same height as the front wheels 11. After that, the front wheels 11 and rear wheels 13 are driven forward, and the vehicle body 10 moves forward, placing the middle wheels 12 onto the second ground surface F2 located beyond the step D1. When the middle wheel 12 is lifted in this way, the front side of the rocker link body 30 lifts further, increasing the inclination. Consequently, the cargo bed 41 also attempts to tilt in a similar manner. The control unit 60 measures this change in the attitude of the cargo bed 41 with the attitude sensor 50 and drives the linear actuator 43 of the front support mechanism 42A and the linear actuator 43 of the rear support mechanism 42B to extend or retract in accordance with the tilting movement of the rocker link body 30, so that the cargo bed 41 remains horizontal. Specifically, the linear actuator 43 of the rear support mechanism 42B is extended, for example, so that the difference in length between the linear actuator 43 of the front support mechanism 42A and the linear actuator 43 of the rear support mechanism 42B becomes even greater than the state shown in Figure 5. At this time, for example, the linear actuator 43 of the front support mechanism 42A may be further retracted.

[0039] As shown in Figure 6, when the linear actuators 43 of the front support mechanism 42A and the rear support mechanism 42B are extended or retracted, and the difference in the length of the linear actuators 43 changes significantly, the change in the distance between the upper ends of the front support mechanism 42A and the rear support mechanism 42B also becomes large enough that it cannot be absorbed by the ball joint. As explained using Figure 6, when the inclination of the rocker link body 30 increases, the control unit 60 controls each linear actuator 43 so that the difference in length between the front support mechanism 42A and the rear support mechanism 42B increases in order to maintain a horizontal position of the cargo bed 41. In such cases, the distance between the upper ends of the front support mechanism 42A and the rear support mechanism 42B tends to increase, so the control unit 60 controls the rotating support section 44 so that the distance between the upper ends of the front support mechanism 42A and the rear support mechanism 42B does not increase but remains constant, by rotating the front support mechanism 42A toward the rear. Instead of rotating the front support mechanism 42A toward the rear, the rear support mechanism 42B may be rotated toward the front. As shown in Figure 6, when raising the front wheels 11 or the middle wheels 12, it is preferable to rotate the front support mechanism 42A toward the rear to move the center of gravity of the cargo bed 41 toward the rear, since a smaller load acting on the front wheels 11 or the middle wheels 12 makes it easier to raise them. Conversely, if the control unit 60 controls each linear actuator 43 so that the difference in length between the front support mechanism 42A and the rear support mechanism 42B is small, the distance between the upper ends of the front support mechanism 42A and the rear support mechanism 42B will tend to decrease. Therefore, the control unit 60 controls the rotating support unit 44 so that the front support mechanism 42A is rotated forward, and the distance between the upper ends of the front support mechanism 42A and the rear support mechanism 42B does not decrease but remains constant. Instead of rotating the front support mechanism 42A forward, the rear support mechanism 42B may be rotated backward.

[0040] In Figure 6, the middle wheel 12 is raised to the same height as the front wheel 11, and then the front wheel 11 and rear wheel 13 are driven forward to move the vehicle body 10 forward, placing the middle wheel 12 on the second ground surface F2 located beyond the step D1. Alternatively, the front wheel 11 may be raised to the second ground surface F2, then the front wheel 11 and rear wheel 13 are driven forward to move the vehicle body 10 forward, bringing the middle wheel 12 into contact with the vertical surface Fv, and in this state, the middle wheel 12 is rotated so that the frictional force generated between the middle wheel 12 and the vertical surface Fv causes the rotating middle wheel 12 to kick up the vertical surface Fv, moving the middle wheel 12 upward along the vertical surface Fv.

[0041] The change in angle between the linear actuator 43 and the loading platform 41, caused by the operation of the linear actuator 43 and the rotation support section 44, is absorbed by the angle adjustment mechanism 45. This is also true for each operation described later, so explanations for each operation will be omitted thereafter.

[0042] Figure 7 shows a rocker bogie vehicle ascending a step, with the rear wheels initially contacting the vertical surface of the step before rising. Subsequently, the rocker bogie car 1 is moved further forward, and the rear wheels 13 are brought into contact with the vertical surface Fv of the step D1. In this state, the rear wheels 13 are rotated, and the frictional force generated between the rear wheels 13 and the vertical surface Fv causes the rotationally driven rear wheels 13 to kick up the vertical surface Fv, moving the rear wheels 13 upward along the vertical surface Fv. At the same time, the bogie link control motor 37 rotates the bogie link 20 around the intermediate part 21c, which is pivotally supported by the rocker link 32, so that the rear wheels 13 rise. As a result, the rear wheels 13 rise up to the second ground surface F2. When the rear wheels 13 are lifted in this manner, the rear side of the rocker link body 30 is lifted upward, and the tilt angle of the rocker link body 30 decreases. Consequently, the posture of the cargo bed 41 also attempts to change. The control unit 60 measures this change in the posture of the cargo bed 41 with the posture sensor 50 and drives the linear actuator 43 of the front support mechanism 42A and the linear actuator 43 of the rear support mechanism 42B to extend or retract in accordance with the movement of the rocker link body 30 so that the cargo bed 41 remains horizontal. Specifically, for example, the linear actuator 43 of the rear support mechanism 42B is retracted. Alternatively, for example, the linear actuator 43 of the front support mechanism 42A may be extended.

[0043] At this time, the control unit 60 controls each linear actuator 43 so that the difference in length between the front support mechanism 42A and the rear support mechanism 42B becomes smaller, and the distance between the upper ends of the front support mechanism 42A and the rear support mechanism 42B tends to decrease. For this reason, as already explained, the control unit 60 controls the rotating support unit 44 so that the distance between the upper ends of the front support mechanism 42A and the rear support mechanism 42B does not decrease but remains constant, by rotating the front support mechanism 42A forward or the rear support mechanism 42B backward.

[0044] In this way, the rocker bogie truck 1 can maintain the cargo bed 41 in a horizontal position when climbing the step D1.

[0045] Incidentally, in the rocker bogie vehicle 1 described above, when going up or down a step D1, it is also possible to move the center of gravity of the cargo bed 41 relative to the vehicle body 10 in the front-rear direction while keeping the cargo bed 41 in a horizontal position. Figure 8 shows the state in which a rocker bogie truck moves the center of gravity of the cargo bed forward and then raises the rear wheels when climbing a step. For example, if you want to raise the rear wheels 13 following the state shown in Figure 6, you can perform the following operation as shown in Figure 8 instead of the operation described using Figure 7. Specifically, before raising the rear wheels 13, the control unit 60 synchronously controls the rotation support section 44 of the front support mechanism 42A and the rotation support section 44 of the rear support mechanism 42B, and the linear actuator 43 of the front support mechanism 42A and the linear actuator 43 of the rear support mechanism 42B, so that they rotate and tilt forward relative to the rocker link body 30. Then, as shown in Figure 8, the rear wheels 13 are raised in the same manner as described in Figure 7 to climb the step D1. As a result, the loading platform 41 moves forward compared to the case shown in Figure 7, and the center of gravity of the loading platform 41 moves forward relative to the vehicle body 10. Consequently, the load from the loading platform 41 acting on the rear wheels 13 is reduced, which prevents the rocker bogie vehicle 1 from tipping over backward and allows the rear wheels 13 to easily move up along the vertical plane Fv.

[0046] Thus, from the perspective of controlling the center of gravity, for example, when raising the front wheels 11 or middle wheels 12 as shown in Figures 5 and 6, the control unit 60 may synchronously control the rotation support section 44 of the front support mechanism 42A and the rotation support section 44 of the rear support mechanism 42B, and the linear actuator 43 of the front support mechanism 42A and the linear actuator 43 of the rear support mechanism 42B, so that they rotate and tilt toward the rear with respect to the rocker link body 30. In this case, the cargo bed 41 moves further rearward compared to the case shown in Figures 5 and 6, and the center of gravity of the cargo bed 41 moves toward the rearward relative to the vehicle body 10. As a result, the load from the cargo bed 41 acting on the front wheels 11 and middle wheels 12 is reduced, so the front wheels 11 and middle wheels 12 can be easily raised. However, care must be taken to prevent the rocker bogie vehicle 1 from tipping over backward due to the shift in the center of gravity of the cargo bed 41 to the rear. Specifically, in Figure 5, if the center of gravity of the cargo bed 41 shifts too far behind the rear wheels 13, it becomes more prone to tipping over. In Figure 6, the center of gravity of the cargo bed 41 is supported by the front wheels 11 and the rear wheels 13, and by shifting the center of gravity of the cargo bed 41 forward before moving to Figure 7, it is possible to avoid tipping over backward when going up a step and to make it easier to lift the rear wheels 13.

[0047] Figure 9 shows the state after the rocker bogie vehicle has climbed the step and reached the second ground surface. After ascending the step D1, as shown in Figure 9, the control unit 60 synchronously controls the rotation support section 44 of the front support mechanism 42A and the rotation support section 44 of the rear support mechanism 42B, returning the inclination of the linear actuator 43 of the front support mechanism 42A and the linear actuator 43 of the rear support mechanism 42B to their initial state. As a result, the center of gravity of the cargo bed 41 returns to its original state before the rocker bogie car 1 ascended the step D1.

[0048] Figure 10 shows a rocker bogie vehicle descending a step, with the front wheels in contact with the vertical surface beyond the step as it descends. As shown in Figure 10, if there is a step D2 in front of the rocker bogie car 1 in the direction of travel, having a vertical surface Fw extending downward from the second ground surface F2, and beyond the step D2 is a horizontal first ground surface F1 that is lower than the second ground surface F2 and is continuous with the second ground surface F2 by the vertical surface Fv, the rocker bogie car 1 first lowers the front wheels 11 onto the first ground surface F1 with the middle wheels 12 and rear wheels 13 in contact with the second ground surface F2. To do this, the front wheels 11 are extended forward from the vertical surface Fw of the step D2 so that the front wheels 11 make contact with the vertical surface Fw. In this state, the front wheel 11 is rotated, and while the frictional force generated between the front wheel 11 and the vertical surface Fw suppresses the front wheel 11 from falling, the front wheel 11 is moved downward along the vertical surface Fw so that it gradually descends the vertical surface Fw with the rotationally driven front wheel 11, and the bogie link control motor 37 rotates the bogie link 20 around the intermediate part 21c which is pivotally supported by the rocker link 32 so that the front wheel 11 descends. As a result, the front wheel 11 is lowered from the second ground surface F2 and made contact with the first ground surface F1 which is lower than the middle wheel 12 and the rear wheel 13.

[0049] When the front wheels 11 are lowered in this manner, the front side of the rocker link body 30 lowers and tilts diagonally, rising from front to rear. Consequently, the cargo bed 41 also attempts to tilt diagonally in a similar manner. The control unit 60 measures this change in the attitude of the cargo bed 41 with the attitude sensor 50 and drives the linear actuator 43 of the front support mechanism 42A and the linear actuator 43 of the rear support mechanism 42B to extend or retract in accordance with the tilting movement of the rocker link body 30, so that the cargo bed 41 remains horizontal. Specifically, the linear actuator 43 of the rear support mechanism 42B is retracted, for example, so that the linear actuator 43 of the front support mechanism 42A becomes longer than the linear actuator 43 of the rear support mechanism 42B. Alternatively, the linear actuator 43 of the front support mechanism 42A may be extended at this time.

[0050] In this embodiment, when lowering the front wheels 11 from the step D2 in this manner, before lowering the front wheels 11, the control unit 60 synchronously controls the rotation support section 44 of the front support mechanism 42A and the rotation support section 44 of the rear support mechanism 42B, and the linear actuator 43 of the front support mechanism 42A and the linear actuator 43 of the rear support mechanism 42B, so that they rotate and tilt toward the rear with respect to the rocker link body 30, as shown in Figure 10. As a result, the loading platform 41 moves backward, and the center of gravity of the loading platform 41 moves backward with respect to the vehicle body 10. As a result, the load from the loading platform 41 acting on the front wheels 11 is reduced, so that the front wheels 11 can be easily lowered along the vertical plane Fw while preventing the rocker bogie vehicle 1 from tipping forward.

[0051] Figure 11 shows a rocker bogie vehicle descending a step, with the front wheels in contact with the first ground surface beyond the step. Starting from the state shown in Figure 10, as the front wheel 11 is lowered along the vertical plane Fw, the bogie link 20 is further rotated around the intermediate section 21c, which is pivotally supported by the rocker link 32, so that the front wheel 11 descends. As a result, the front of the rocker link body 30 lowers further and tilts even more sharply, and the cargo bed 41 also attempts to tilt similarly as a result. The control unit 60 measures this change in the posture of the cargo bed 41 with the posture sensor 50 and, in order to maintain the cargo bed 41 in a horizontal state, further drives the linear actuator 43 of the front support mechanism 42A and the linear actuator 43 of the rear support mechanism 42B to extend and retract in accordance with the tilting movement of the rocker link body 30. Specifically, for example, if the linear actuator 43 of the rear support mechanism 42B is set to retract in the state shown in Figure 10, this retraction operation may be continued, or if the linear actuator 43 of the rear support mechanism 42B reaches its retraction limit during the retraction operation, the control unit 60 may control the linear actuator 43 of the front support mechanism 42A to extend it.

[0052] Subsequently, as shown in Figure 11, once the front wheels 11 make contact with the first ground surface F1 beyond the step D2, the possibility of the rocker bogie car 1 tipping forward is reduced. Therefore, the control unit 60 synchronously controls the rotation support section 44 of the front support mechanism 42A and the rotation support section 44 of the rear support mechanism 42B, and the linear actuator 43 of the front support mechanism 42A and the linear actuator 43 of the rear support mechanism 42B, so that they rotate and tilt forward relative to the rocker link body 30. As a result, the center of gravity of the cargo bed 41 shifts towards the side of the front wheels 11 that have made contact with the first ground surface F1.

[0053] Figure 12 shows a rocker bogie vehicle descending a step, with the middle wheel moving downward towards the second ground surface beyond the step. Next, with the front wheel 11 in contact with the first ground surface F1 and the rear wheel 13 in contact with the second ground surface F2, when the middle wheel 12 reaches the vertical surface Fw, as shown in Figure 12, the bogie link control motor 37 rotates the bogie link 20 around the intermediate part 21c pivotally supported by the rocker link 32 in the direction that the middle wheel 12 descends. The frictional force generated between the middle wheel 12 and the vertical surface Fw suppresses the middle wheel 12 from falling, and the front wheel 11 is lowered along the vertical surface Fw to the first ground surface F1, so that the rotationally driven middle wheel 12 gradually descends the vertical surface Fw. When the middle wheel 12 is lowered in this manner, the front side of the rocker link body 30 lowers further and tilts even more sharply, and the cargo bed 41 also attempts to tilt similarly in conjunction with it. The control unit 60 measures this change in the posture of the cargo bed 41 with the posture sensor 50 and drives the linear actuator 43 of the front support mechanism 42A and the linear actuator 43 of the rear support mechanism 42B to extend or retract in accordance with the tilting movement of the rocker link body 30 so that the cargo bed 41 remains horizontal. Specifically, for example, the linear actuator 43 of the front support mechanism 42A is extended to become longer.

[0054] Furthermore, when lowering the middle wheel 12 from the step D2 in this manner, before lowering the middle wheel 12, the control unit 60 synchronously controls the rotation support section 44 of the front support mechanism 42A and the rotation support section 44 of the rear support mechanism 42B, and the linear actuator 43 of the front support mechanism 42A and the linear actuator 43 of the rear support mechanism 42B, so that they rotate and tilt toward the rear relative to the rocker link body 30. As a result, the loading platform 41 moves further rearward compared to the case shown in Figure 11, and the center of gravity of the loading platform 41 moves toward the rear relative to the vehicle body 10. Consequently, the load from the loading platform 41 acting on the front wheel 11 and the middle wheel 12 is reduced, so that the rocker bogie vehicle 1 can be prevented from tipping forward, and the middle wheel 12 can be easily lowered along the vertical plane Fw. Figure 13 shows a rocker bogie vehicle descending a step, with the middle wheel in contact with the second ground surface.

[0055] After the middle wheel 12 reaches the first ground surface F1, the rocker bogie car 1 is moved forward with the front wheel 11 and the middle wheel 12 in contact with the first ground surface F1 and the rear wheel 13 in contact with the second ground surface F2. Then the rear wheel 13 reaches the vertical surface Fw. In this case, the bogie link control motor 37 rotates the bogie link 20 around the intermediate part 21c pivotally supported by the rocker link 32 in the direction that the rear wheel 13 descends. The frictional force generated between the rear wheel 13 and the vertical surface Fw suppresses the rear wheel 13 from falling, and the rear wheel 13 is gradually lowered along the vertical surface Fw to the first ground surface F1 by the rotationally driven rear wheel 13. When the rear wheels 13 are lowered in this manner, the rear side of the rocker link body 30 lowers, and the tilt angle of the rocker link body 30 decreases. Consequently, the posture of the cargo bed 41 also attempts to change. The control unit 60 measures this change in the posture of the cargo bed 41 with the posture sensor 50 and, in order to maintain the cargo bed 41 in a horizontal position, drives the linear actuator 43 of the front support mechanism 42A and the linear actuator 43 of the rear support mechanism 42B to extend or retract in accordance with the movement of the rocker link body 30. Specifically, it extends the linear actuator 43 of the rear support mechanism 42B.

[0056] Subsequently, when the rear wheels 13 reach the first ground surface F1, the rocker bogie car 1 overcomes the step D2. In this embodiment, when lowering the rear wheels 13 from the step D2 in this manner, before lowering the rear wheels 13, the control unit 60 synchronously controls the rotation support section 44 of the front support mechanism 42A and the rotation support section 44 of the rear support mechanism 42B, and the linear actuator 43 of the front support mechanism 42A and the linear actuator 43 of the rear support mechanism 42B, so that they rotate and tilt forward relative to the rocker link body 30. As a result, the center of gravity of the cargo bed 41 moves forward relative to the vehicle body 10, and the load from the cargo bed 41 acting on the rear wheels 13 is reduced, so that when the rear wheels 13 lower and make contact with the first ground surface F1, the impact on the items placed on the cargo bed 41 can be reduced.

[0057] The rocker bogie vehicle 1 described above is a rocker bogie vehicle 1 for transporting goods loaded on a cargo bed 41, with a pair of front wheels 11, middle wheels 12, and rear wheels 13 each provided on the left and right sides, and having a bogie link 20 that pivots on the front wheels 11 and middle wheels 12 and connects them, a rocker link body 30 having a rocker link 32 that pivots on the intermediate part 21c between the front wheels 11 and middle wheels 12 of the bogie link 20 and the rear wheels 13 and connects them, and the rocker link body 30 and the cargo bed 41 The system includes a cargo bed support mechanism 42 that supports the cargo bed 41, and a control unit 60. The cargo bed support mechanism 42 includes a front support mechanism 42A and a rear support mechanism 42B, which are provided on the front and rear sides of the rocker link body 30, respectively. Both the front support mechanism 42A and the rear support mechanism 42B are equipped with linear actuators 43 that are provided to adjust the distance between the rocker link body 30 and the cargo bed 41. The control unit 60 controls the linear actuators 43 to extend and retract so that the cargo bed 41 becomes horizontal. With this configuration, the rocker bogie car 1 is equipped with a bogie link 20 that pivots on the front wheels 11 and the middle wheels 12 and connects them, and a rocker link 32 that pivots on the intermediate part 21c between the front wheels 11 and the middle wheels 12 of the bogie link 20 and connects the rear wheels 13, thereby enabling it to travel on uneven terrain. In particular, when traveling over steps D1 and D2, for example, when the rocker bogie car 1 is positioned on the first ground surface F1 and ascends from the first ground surface F1 to the second ground surface F2, which is higher than the first ground surface F1 and located beyond the step D1, the rocker bogie car first places the middle wheels 12 and the rear wheels 13 in contact with the first ground surface F1, and rotates the bogie link 20 around the intermediate part 21c pivotally supported by the rocker link 32, raising the front wheels 11 higher than the middle wheels 12 and the rear wheels 13, and then moves forward in that state, causing the front wheels 11 to touch the second ground surface F2. Next, the bogie link 20 is rotated in the opposite direction, raising the middle wheel 12 to the same height as the front wheel 11. In this state, the vehicle is moved forward further, so that both the front wheel 11 and the middle wheel 12 make contact with the second ground surface F2. Then, while supporting the vehicle body with the front wheel 11 and the middle wheel 12 and moving forward, the rear wheel 13 is raised to the second ground surface F2 by kicking up the vertical surface Fv with the rear wheel 13. As a result, the rocker bogie vehicle 1 can climb over the step D1. It is also possible to descend the step D2 using a similar procedure, and in this way the rocker bogie vehicle 1 can overcome steps D1 and D2 and continue to travel. In this way, when the rocker bogie vehicle 1 travels over uneven terrain or steps D1 and D2, it is necessary to displace one of the front wheels 11, middle wheels 12, or rear wheels 13 to a position at a different height than the others. As a result, both the bogie links 20 and the rocker links 32 change their angle with respect to the horizontal plane, and consequently, the cargo bed 41, which is supported by the cargo bed support mechanism 42 on the rocker link body 30 having the rocker links 32, also tends to tilt with respect to the horizontal plane. Here, the cargo bed support mechanism 42 includes a front support mechanism 42A and a rear support mechanism 42B, which are provided on the front and rear sides of the rocker link body 30, respectively. Both the front support mechanism 42A and the rear support mechanism 42B are equipped with linear actuators 43 that are provided to adjust the distance between the rocker link body 30 and the cargo bed 41, and the control unit 60 controls the linear actuators 43 to extend and retract so that the cargo bed 41 becomes horizontal. For example, when the rocker link body 30 is tilted so that the front side is lifted relative to the rear side, the cargo bed 41 can be controlled to become horizontal by retracting the linear actuator 43 of the front support mechanism 42A, extending the linear actuator 43 of the rear support mechanism 42B, or by combining these actions. Also, when the rocker link body 30 is tilted so that the front side is lowered relative to the rear side, the cargo bed 41 can be controlled to become horizontal by extending the linear actuator 43 of the front support mechanism 42A, retracting the linear actuator 43 of the rear support mechanism 42B, or by combining these actions. Furthermore, as described above, since the cargo bed 41 is controlled to be horizontal, driving stability is maintained even when traveling on uneven terrain or over steps, thereby improving driving performance. In this way, even when traveling over uneven terrain or steps D1 and D2, the cargo bed 41 is controlled to remain horizontal, which in turn suppresses the collapse of goods loaded on the cargo bed 41 and improves driving performance.

[0058] Furthermore, the linear actuator 43 is provided on both the front support mechanism 42A and the rear support mechanism 42B. Each of the front support mechanism 42A and the rear support mechanism 42B is connected to the rocker link body 30 via a rotation support part 44 so that it can rotate in the front-rear direction relative to the rocker link body 30. The control unit 60 controls the rotation of the rotation support part 44 relative to the rocker link body 30 while extending and retracting the linear actuator 43, thereby controlling the loading platform 41 to be horizontal. With this configuration, the linear actuators 43 are provided on both the front support mechanism 42A and the rear support mechanism 42B. Each of the front support mechanism 42A and the rear support mechanism 42B is connected to the rocker link body 30 via a rotation support part 44 so that it can rotate in the front-rear direction relative to the rocker link body 30. Therefore, each linear actuator 43 can be rotated while extending and contracting individually. As a result, even when traveling over larger steps D1, D2 or uneven terrain with vertical movement, the control unit 60 can flexibly control the load bed 41 to remain horizontal in response to these conditions. Furthermore, when the rocker link body 30 of the rocker bogie car 1 tilts significantly and the linear actuator 43 extends or retracts significantly, simply extending or retracting the linear actuator 43 would change the distance between the ends of the front support mechanism 42A and the rear support mechanism 42B that are connected to the loading platform 41, and the extension or retraction would be hindered by the rigidity of the loading platform 41. Here, the front support mechanism 42A and the rear support mechanism 42B are connected to the rocker link body 30 via a rotation support part 44 so that they can rotate in the front-rear direction relative to the rocker link body 30, and the control unit 60 controls the rotation of the rotation support part 44 relative to the rocker link body 30 while extending or retracting the linear actuator 43, thereby controlling the loading platform 41 to be horizontal. Therefore, for example, while extending or retracting the linear actuator 43, it becomes possible to rotate the front support mechanism 42A and the rear support mechanism 42B by controlling the rotation of the rotation support section 44 so that the distance between the ends of the front support mechanism 42A and the rear support mechanism 42B on the cargo bed 41 side remains constant, thereby suppressing the restriction of the extension and retraction operation of the linear actuator 43.

[0059] Furthermore, the front support mechanism 42A and the rear support mechanism 42B are connected to the cargo bed 41 via an angle adjustment mechanism 45, which allows the angle relative to the cargo bed 41 to be adjusted at least in the front-rear direction. With this configuration, when the rocker link body 30 of the rocker bogie car 1 is tilted and the linear actuators 43 of the front support mechanism 42A and the rear support mechanism 42B are extended or retracted so that the cargo bed 41 becomes horizontal, the angle of the front support mechanism 42A and the rear support mechanism 42B with respect to the cargo bed 41 may change. In this configuration, since each of the front support mechanism 42A and the rear support mechanism 42B is connected to the cargo bed 41 via an angle adjustment mechanism 45 whose angle with respect to the cargo bed 41 is adjustable at least in the front-rear direction, they can follow the change in the angle of the front support mechanism 42A and the rear support mechanism 42B with respect to the cargo bed 41.

[0060] Furthermore, when raising or lowering the front wheels 11, the control unit 60 rotates the rotational support parts 44 of both the front support mechanism 42A and the rear support mechanism 42B toward the rear relative to the rocker link body 30, thereby controlling the movement of the cargo bed 41 toward the rear. With this configuration, for example, when raising the front wheels 11 when going up a step D1, the rotational support parts 44 of both the front support mechanism 42A and the rear support mechanism 42B are rotated toward the rear relative to the rocker link body 30, thereby controlling the loading platform 41 to move backward. As a result, the center of gravity of the loading platform 41 moves backward, reducing the load acting on the front wheels 11 and making it easier to raise the front wheels 11. Furthermore, when descending the step D2, if the front wheels 11 are lowered, the rotational support parts 44 of both the front support mechanism 42A and the rear support mechanism 42B are rotated rearward relative to the rocker link body 30, thereby controlling the movement of the loading platform 41 to the rear. As a result, the center of gravity of the loading platform 41 shifts to the rear, preventing the rocker bogie car 1 from tipping forward due to the load and falling below the step D2 while the front wheels 11 are not supported by the ground surfaces F1 and F2 and are floating in the air until they make contact with the ground surface F1 located beyond the step D2.

[0061] Furthermore, when the rear wheels 13 are raised, the control unit 60 rotates the rotational support parts 44 of both the front support mechanism 42A and the rear support mechanism 42B toward the front relative to the rocker link body 30, thereby controlling the movement of the cargo bed 41 forward. With this configuration, for example, when climbing a step D1, the front wheels 11 and middle wheels 12 first make contact with the ground surface F2 located beyond the step (upper step) D1, and with the vehicle body supported by the front wheels 11 and middle wheels 12, the rear wheels 13 are raised to the same height as the front wheels 11 and middle wheels 12. When raising the rear wheels 13, the rotational support parts 44 of both the front support mechanism 42A and the rear support mechanism 42B are rotated forward relative to the rocker link body 30, and the loading platform 41 is controlled to move forward. As a result, the center of gravity of the loading platform 41 moves forward, the load acting on the rear wheels 13 is reduced, making it easier to raise the rear wheels 13, and preventing the rocker bogie vehicle 1 from tipping over backward and falling below the step D1 due to the load.

[0062] Furthermore, each of the front support mechanism 42A and the rear support mechanism 42B is provided in pairs on the left and right sides. With this configuration, the tilting of the cargo bed 41 in the lateral direction is suppressed, and the cargo bed 41 can be supported stably. Furthermore, even if the rocker link body 30 tilts laterally, for example, so that the right side of the rocker link body 30 rises relative to the left side, the loading platform 41 can be controlled to be horizontal by, for example, contracting the front support mechanism 42A and the rear support mechanism 42B provided on the right side, or extending the front support mechanism 42A and the rear support mechanism 42B provided on the left side. Similarly, even if the right side of the rocker link body 30 descends relative to the left side, the loading platform 41 can be controlled to be horizontal by, for example, extending the front support mechanism 42A and the rear support mechanism 42B provided on the right side, or contracting the front support mechanism 42A and the rear support mechanism 42B provided on the left side. In this way, the loading platform 41 can be controlled to be horizontal not only in the longitudinal direction but also when the rocker link body 30 tilts laterally.

[0063] Furthermore, the rocker bogie car 1 is equipped with a posture sensor 50 capable of measuring the posture of the cargo bed 41, and the control unit 60 controls the rotation of the rotary support unit 44 while extending and retracting the linear actuator 43 based on the measurement results of the posture sensor 50, so that the cargo bed 41 becomes horizontal. With this configuration, a rocker bogie vehicle 1 can be realized that can suppress the collapse of goods loaded on the cargo bed 41 and improve driving performance, even when traveling on uneven terrain or over steps.

[0064] (Other variations) In the above embodiment, both the front support mechanism 42A and the rear support mechanism 42B are equipped with a linear actuator 43, but the embodiment is not limited to this. Either the front support mechanism 42A or the rear support mechanism 42B may be equipped with a linear actuator 43. For example, the linear actuator 43 may be provided only on the front support mechanism 42A, and not on the rear support mechanism 42B. In this case, when the rocker link body 30 is tilted so that the front side is lifted relative to the rear side, the linear actuator 43 is retracted, and when the rocker link body 30 is tilted so that the front side is lowered relative to the rear side, the linear actuator 43 is extended, thereby controlling the loading platform 41 to be horizontal. Alternatively, the linear actuator 43 may be provided only on the rear support mechanism 42B, and not on the front support mechanism 42A. In this case, the linear actuator 43 can be extended when the rocker link body 30 is tilted so that the front side is lifted relative to the rear side, and the linear actuator 43 can be retracted when the rocker link body 30 is tilted so that the front side is lowered relative to the rear side, thereby controlling the cargo bed 41 to be horizontal.

[0065] Furthermore, in the above embodiment, the cargo bed support mechanism 42 is provided with one on the front and one on the rear, for a total of four, but it is not limited to this. The cargo bed support mechanism 42 may be provided with one on the front and one on the rear, for a total of two. In this case, in order to prevent the cargo bed 41 from tilting in the left-right direction, it is preferable that the angle adjustment mechanism 45 rotatably connects the upper end of the linear actuator 43 and the cargo bed 41 around an axis extending in the left-right direction. Alternatively, the cargo bed support mechanism 42 may be provided with one on the front side and one on each side of the rear, for a total of three, or with one on each side of the front side and one on the rear, for a total of three. In addition to the above, the cargo bed support mechanism 42 may also be provided with, for example, five or more sets.

[0066] Furthermore, in the above embodiment, the linear actuator 43 and the loading platform 41 are connected by an angle adjustment mechanism 45. However, instead, the linear actuator 43 and the loading platform 41 may be connected by a flexible member such as rubber.

[0067] Furthermore, in the above embodiment, when the rocker link body 30 of the rocker bogie car 1 is tilted significantly and the linear actuator 43 is extended or retracted significantly, simply extending or retracting the linear actuator 43 would cause displacement at the ends of the front support mechanism 42A and the rear support mechanism 42B on the cargo bed 41 side, resulting in a change in the distance between the ends of the front support mechanism 42A and the rear support mechanism 42B. As a result, extension and retraction may be hindered by the rigidity of the cargo bed 41. Therefore, the control unit 60 rotates the rotation support unit 44 so that the front support mechanism 42A and the rear support mechanism 42B rotate so that the distance between the ends of the front support mechanism 42A and the rear support mechanism 42B on the cargo bed 41 side remains constant, while extending or retracting the linear actuator 43. However, the means for adjusting the distance between the ends of the front support mechanism 42A and the rear support mechanism 42B are not limited to this. For example, rails may be provided on the underside of the cargo bed 41, and the ends of the front support mechanism 42A and the rear support mechanism 42B may be mounted on the rails so as to slide relative to the rails, thereby allowing them to follow changes in the distance between the ends of the front support mechanism 42A and the rear support mechanism 42B.

[0068] Furthermore, although the rocker bogie vehicle 1 according to this embodiment is intended for autonomous driving, it may also be configured to be remotely controllable in addition to autonomous driving. In addition to the above, it is possible to select or replace the configurations listed in the above embodiments, or to change them to other configurations as appropriate, as long as it does not deviate from the spirit of the present invention. [Explanation of Symbols]

[0069] 1 Rocker bogie car 11 Front Wheel 12 Middle ring 13 Rear wheels 20 Bogey Link 21c middle part 30 Rocker Link Body 32 Locker Link 41 Cargo bed 42. Cargo bed support mechanism 42A Front support mechanism 42B Rear support mechanism 43 Linear Actuator 44 Rotating support section 45 Angle adjustment mechanism 50. Posture Sensor 60 Control Unit

Claims

1. A rocker bogie vehicle in which front wheels, middle wheels, and rear wheels are each provided in pairs on the left and right sides, and which transports goods loaded on a cargo bed, The bogie link supports the front wheel and the middle wheel respectively and connects them, A rocker link body having a rocker link that pivotally supports the intermediate portion of the bogie link between the front wheel and the middle wheel, and the rear wheel, and connects them. A cargo bed support mechanism that connects the rocker link body and the cargo bed and supports the cargo bed, Control unit and Equipped with, The cargo bed support mechanism comprises a front support mechanism and a rear support mechanism provided on the front and rear sides of the rocker link body, respectively, and each of the front support mechanism and the rear support mechanism is equipped with a linear actuator that is provided to adjust the distance between the rocker link body and the cargo bed, and is connected to the rocker link body via a rotation support portion so as to be rotatable in the front-rear direction relative to the rocker link body. The control unit controls the rotation of the rotary support portion relative to the rocker link body while extending and retracting the linear actuator to control the loading platform to become horizontal, and when raising the front wheels, it controls the rotation of the rotary support portions of both the front support mechanism and the rear support mechanism toward the rear relative to the rocker link body to move the loading platform toward the rear.

2. The rocker bogie vehicle according to claim 1, wherein each of the front support mechanism and the rear support mechanism is connected to the loading platform via an angle adjustment mechanism that allows the angle with respect to the loading platform to be adjusted at least in the front-rear direction.

3. The rocker bogie vehicle according to claim 1, wherein the control unit controls the movement of the loading platform backward by rotating the rotation support portions of both the front support mechanism and the rear support mechanism toward the rear relative to the rocker link body when the front wheel is lowered.

4. The rocker bogie vehicle according to claim 1, wherein when the rear wheels are raised, the control unit rotates the rotation support portions of both the front support mechanism and the rear support mechanism toward the front relative to the rocker link body, thereby controlling the movement of the loading platform toward the front.

5. The rocker bogie car according to claim 1, wherein each of the front support mechanism and the rear support mechanism is provided in a pair on the left and right sides.

6. The vehicle is further equipped with a posture sensor capable of measuring the posture of the cargo bed. The rocker bogie vehicle according to claim 1, wherein the control unit controls the rotation of the rotary support part while extending and retracting the linear actuator based on the measurement results of the attitude sensor, so that the loading platform becomes horizontal.

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