Rocker bogie car and method for driving rocker bogie car

Abstract

To provide a rocker bogie car capable of ensuring step trek-across performance.SOLUTION: A rocker bogie car (1), having a total of six wheels constituted of each of a front wheel (11), an intermediate wheel (12) and a rear wheel (13) provided in a pair on the left and right, includes: a bogie link (2) with the front wheel (11) and the intermediate wheel (12) journaled respectively; a rocker link (3) connected with the bogie link (2) and having the rear wheel (13) journaled; a main body (5) connected with the rocker link (3); and an elastic body (a spring 6) disposed between the bogie link (2) and the body (5) or the rocker link (3). The main body (5) or the bogie link (2) can cause lengthwise vibration with a junction (21) connected with the rocker link (3) centered and vibration of the bogie link (2) stores elastic energy in the elastic body (the spring 6).SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a rocker bogie vehicle and a driving method thereof.

Background Art

[0002] Generally, in a moving device that travels by wheels, it is difficult to travel on uneven ground. Therefore, technological development has been promoted to enable such a moving device to travel on uneven ground. As such a technology, a rocker bogie mechanism can be exemplified. In addition, a moving device that travels by wheels is required not only to have a technology for enabling travel on uneven ground but also to have a step-over performance for overcoming steps.

[0003] In the step-over of a rocker bogie vehicle, in order to get the front wheels onto a step, with the front wheels pressed against the step by the propulsive force of the middle wheels and the rear wheels, the front wheels generate an upward climbing force for the step, so as to sufficiently secure the friction between the front wheels and the step, and the front wheels climb over the step. However, when the friction between the front wheels and the step is insufficient or the torque of the front wheels is insufficient, there is a problem that it is difficult to step over the step. Therefore, in Non-Patent Document 1, which is an example of the prior art, by controlling the rocker mechanism, the front wheels are lifted according to the step height to move the vehicle body forward. When the front wheels reach the edge of the step, by controlling the rocker mechanism, the front wheels and the middle wheels are aligned at the same height, and the vehicle body is further moved forward to place the middle wheels on the step. After the rear wheels contact the side surface of the step, the rocker mechanism is returned to the initial position to lift the rear wheels. A six-wheel rocker bogie vehicle having step-over performance is disclosed.

Prior Art Documents

Non-Patent Documents

[0004]

Non-Patent Document 1

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0005] However, the technique disclosed in Non-Patent Document 1 described above has a problem in that a configuration for actively controlling the bogie link in the locker bogie vehicle, for example, a motor for controlling the angle of the bogie link, is required. Such a configuration for actively controlling the bogie link hinders the weight reduction, miniaturization, or simplification of the locker bogie vehicle. In addition, in a passive locker bogie vehicle, there is a problem in that it is difficult to ensure step-over performance when the friction between the front wheels and the step is insufficient or when the torque of the front wheels is insufficient.

[0006] The present invention has been made in view of the above, and an object thereof is to realize a locker bogie vehicle capable of ensuring step-over performance even when the friction between the front wheels and the step is insufficient or the torque of the front wheels is insufficient, or even when a configuration for actively controlling the bogie link is not provided.

MEANS FOR SOLVING THE PROBLEMS

[0007] One aspect of the present invention that solves the above problems and achieves the object is a locker bogie vehicle having a total of six wheels with a pair of front wheels, middle wheels, and rear wheels provided on each side, the bogie links on which the front wheels and the middle wheels are respectively pivotally supported, the rocker link to which the bogie links are connected and on which the rear wheels are pivotally supported, the main body connected to the rocker link, and an elastic body disposed between the bogie link and the main body or the rocker link, the bogie link being capable of vibrating back and forth about a joint point connected to the main body or the rocker link, and elastic energy being accumulated in the elastic body by the vibration of the bogie link.

[0008] In the bogie vehicle with the above configuration, the driving directions of the front wheels, the middle wheels, and the rear wheels are reversely controlled at a predetermined timing, so that the elastic energy accumulated by extending the elastic body from the neutral position of the bogie link can be accumulated and released, enabling the front wheels to be lifted or the middle wheels to be lifted.

[0009] Alternatively, one aspect of the present invention is a driving method for a bogie vehicle with the above configuration, including driving the front wheels, the middle wheels, and the rear wheels forward as forward driving, lifting the middle wheels by driving the front wheels and the middle wheels in reverse when a step is detected in the traveling direction, driving the front wheels forward, driving the middle wheels forward, and driving the rear wheels in reverse with the middle wheels not in contact with the ground, so as to lift the bogie link so that the front wheels are lifted when the middle wheels come into contact with the ground, and when the front wheels climb onto the step, driving the rear wheels forward to advance the bogie vehicle to cross the step.

Advantages of the Invention

[0010] According to the present invention, even when the friction between the front wheels and the step is insufficient or the torque of the front wheels is insufficient, or even when there is no configuration for actively controlling the bogie link, a bogie vehicle capable of ensuring step-crossing performance can be realized.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3a

Figure 3b

Figure 3c

Figure 4

Figure 5

Figure 6

Figure 7a

Figure 7b

Embodiments for Carrying Out the Invention

[0012] Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings. However, the present invention is not to be construed as being limited by the descriptions of the following embodiments.

[0013] (Embodiment) Figure 1 is a left side view showing the configuration of a rocker bogie vehicle 1 according to an embodiment of the present invention. The rocker bogie vehicle 1 shown in Figure 1 is a six-wheel rocker bogie vehicle in which a pair of front wheels 11, middle wheels 12, and rear wheels 13 are provided on each of the left and right sides, and includes two left and right bogie links 2, two left and right rocker links 3, one main body 5, and two left and right springs 6. Although only the left side is shown in Figure 1, the right side has the same configuration.

[0014] The front wheels 11 are pivotally supported by a front wheel shaft 110 that penetrates the bogie link 2. The middle wheel 12 is pivotally supported by a middle wheel shaft 120 that penetrates the bogie link 2. The rear wheel 13 is pivotally supported by a rear wheel shaft 130 that penetrates the rocker link 3. The bogie link 2 and the rocker link 3 are connected at a joint point 21. At the joint point 21, the angle between the bogie link 2 and the rocker link 3 can freely change with respect to the rear wheel 13 and the angles of the front wheel 11 and the middle wheel 12.

[0015] The rocker link 3 and the main body 5 may be connected by a fixed support shaft or may be connected by a movable support shaft.

[0016] When the rocker link 3 and the main body 5 are fixedly connected by a fixed support shaft, the spring 6 is arranged such that when the front wheel 11, the middle wheel 12, and the rear wheel 13 are not in contact with the ground, the positional relationship between the front and middle wheels and the rear wheel becomes a neutral position. One end, the first end 61, is connected to the neutral position of the bogie link 2, and the other end, the second end 62, is connected to the main body 5. In the neutral position, the main body 5 becomes stable when the elastic energy of the spring 6 is released. When controlling the main body 5 and the rocker link 3 to maintain the horizontal state of the main body 5, since the main body 5 and the rocker link 3 vary, the shape of the rocker link 3 in the side view is such that the overlapping portion with the main body 5 is large, and the second end 62 may be arranged on the rocker link 3 instead of the main body 5. When configured to be able to control the center of gravity of the main body 5 as described above, vibration occurs according to the angle between the bogie link 2 to which the front wheel 11 and the middle wheel 12 are connected and the rocker link 3 of the rear wheel 13. Therefore, when controlling the spring 6 to hold the main body 5 in a horizontal state, the spring 6 is arranged not on the main body 5 but between the bogie link 2 and the rocker link 3.

[0017] Note that the spring 6 may be connected by setting an offset angle between the bogie link 2 and the rocker link 3 so that elastic energy is stored in a state where the front wheel 11, the middle wheel 12, and the rear wheel 13 are in contact with the ground. Figure 6 is a diagram showing the offset angle. As shown in Figure 6, based on the line segment connecting the joint point 21 and the second end 62, the angle between the line segment connecting the joint point 21 and the first end 61 is defined as the offset angle. The offset angle is set to be -90° to 90°, and can be, for example, 20°. However, the offset angle is not limited to this range. With such a configuration, torque in the direction of lifting the front wheel 11 by elastic energy can be obtained, and the front wheel 11 is lifted. Figure 7a is a left side view showing the vicinity of a step of the rocker bogie vehicle 1 according to an embodiment of the present invention. As shown in Figure 7a, the rocker bogie vehicle 1 performs reverse driving of the rear wheel 13 immediately before the step, and forward driving of the front wheel 11 and the middle wheel 12. Figure 7b is a left side view showing the operation of lifting the front wheel of the rocker bogie vehicle 1 according to an embodiment of the present invention. When the front wheel 11 collides with the step, the front wheel 11 is lifted and rides onto the step. At that timing, the rear wheel 13 is switched to forward driving. After that, when the middle wheel 12 collides with the step, the middle wheel 12 is lifted and rides onto the step, and then when the rear wheel 13 collides with the step, the rear wheel 13 is lifted and rides onto the step. In this way, the spring 6 is a configuration for vibration and can also function as a configuration for generating an auxiliary force when lifting the front wheel 11. Conversely, for example, when the center of gravity of the rocker bogie vehicle 1 exists behind the middle wheel 12, although the front wheel 11 can be easily lifted, when it is not easy to lift the middle wheel 12, it is preferable to set the balance position closer to the middle wheel lifting support, and configure the spring 6 to generate an auxiliary force when lifting the middle wheel 12. That is, when a negative offset angle is set in the opposite direction to the above example, it becomes possible to generate an auxiliary force when placing the middle wheel 12 on a step without a riser. In this way, the function of the spring 6 can be adjusted by setting the offset angle.

[0018] The bogie link 2 can oscillate back and forth about the joint point 21 connected to the rocker link 3. Elastic energy is accumulated in the spring 6 due to the back-and-forth oscillation of the bogie link 2.

[0019] In addition, as described above, when the rocker link and the main body are connected by a movable support shaft, it may be configured to be able to control the center of gravity of the main body that changes according to the running state. That is, a configuration may be provided for tilting the main body with respect to the rocker link at an arbitrary angle and holding that state.

[0020] FIG. 4 is a left side view showing the configuration of the rocker bogie vehicle 1a according to an embodiment of the present invention which is a modified example. The rocker bogie vehicle 1a shown in FIG. 4 is a six-wheel rocker bogie vehicle in which a pair of front wheels 11, middle wheels 12, and rear wheels 13 are provided on each side. It is the same as the rocker bogie vehicle 1 shown in FIG. 1 in that it includes two left and right bogie links 2, one main body 5, and two left and right springs 6, but is different from the rocker bogie vehicle 1 shown in FIG. 1 in that it includes two rocker links 3a instead of two rocker links 3. The spring 6 shown in FIG. 4 has a first end portion 61 at one end connected to the neutral position of the bogie link 2, and a second end portion 62 at the other end connected to the rocker link 3a. As shown in FIG. 4, the rocker link 3a is in a shape extended to the position of the second end portion 62 of the spring 6. The rocker bogie vehicle 1a shown in FIG. 4 can tilt the main body 5 with respect to the rocker link 3a at an arbitrary angle and maintain a horizontal state.

[0021] FIG. 2 is a left side view showing the back-and-forth oscillation of the bogie link 2 in the rocker bogie vehicle 1 according to the embodiment of the present invention. The front wheels 11 and the middle wheels 12 are integrated by the bogie link 2. However, due to the elastic energy of the spring 6 arranged on the bogie link 2, the front wheels 11 move to the position of the front wheels 11', the middle wheels 12 move to the position of the middle wheels 12', the bogie link 2 moves to the position of the bogie link 2', and the spring 6 moves to the position of the spring 6', resulting in a pendulum-like vibration and enabling the acceleration of the lifting of the front wheels 11 and the middle wheels 12.

[0022] Here, the relationship between the total weight mg of the rocker bogie vehicle 1, the force N1 received by the front wheels 11 from the ground contact surface, the force N2 received by the middle wheels 12 from the ground contact surface, and the force N3 received by the rear wheels 13 from the ground contact surface is mg = N1 + N2 + N3. Also, assuming that the forces applied to the front wheels 11, the middle wheels 12, and the rear wheels 13 are equal, then N1 = N2 = N3.

[0023] And, using the distance A2 on the ground contact surface between the joint point 21 and the middle wheel axle 120, the distance A1 on the ground contact surface between the joint point 21 and the front wheel axle 110, the distance B2 on the ground contact surface between the center of gravity position of the rocker bogie vehicle 1 and the rear wheel axle 130, and the distance B1 on the ground contact surface between the center of gravity position of the rocker bogie vehicle 1 and the joint point 21, by the balance of moments, A2 × N2 = A1 × N1 holds, B2 × N3 = B1 × (N1 + N2) holds, and A1 = A2, B2 = 2 × B1. However, the present invention is not limited to this.

[0024] Each of the six wheels of the rocker bogie vehicle 1 is driven by a motor capable of independent control. The two front wheels 11 and the two middle wheels 12 are capable of vibrating around the joint point 21. The spring 6 arranged at the neutral position of the bogie link 2 accumulates elastic energy when it extends due to the independent drive of each wheel. And when the elastic energy accumulated in the spring 6 is released, the front wheels 11 or the middle wheels 12 are lifted.

[0025] FIG. 3a is a left side view showing the forward running of the rocker bogie vehicle 1 according to an embodiment of the present invention. As shown in FIG. 3a, when the rocker bogie vehicle 1 is moving forward, all of the front wheels 11, the middle wheels 12, and the rear wheels 13 are driven forward.

[0026] FIG. 3b is a left side view showing the operation of lifting the middle wheels in the rocker bogie vehicle 1 according to an embodiment of the present invention. As shown in FIG. 3b, when the rocker bogie vehicle 1 detects a step in the traveling direction by a sensor (not shown) or the like, the rocker bogie vehicle 1 performs a lifting operation of the two middle wheels 12. At this time, the two front wheels 11 and the two middle wheels 12 are driven in reverse, and the two rear wheels 13 are driven forward. By the frictional force generated between the two front wheels 11 and the two middle wheels 12 and the ground surface or the frictional force generated between the two front wheels 11 and the ground surface, the spring 6 is extended from the neutral position of the bogie link 2 to accumulate elastic energy, and the middle wheels 12 can be lifted. Then, when the lifted position of the middle wheels 12 reaches near the highest point, the driving torques of the front wheels 11 and the rear wheels 13 are reversed, and the angle of the bogie link 2 is changed. Here, the detection near the highest point of the lifted position of the middle wheels 12 is performed, for example, by detecting the angular velocity of the bogie link 2 using a gyro sensor (not shown), or by detecting the acceleration, or by measuring the relative angle between the bogie link 2 and the rocker link 3 with an angle sensor such as a rotary encoder. Near the highest point of the lifted position of the middle wheels 12 is the position where the direction of the angular velocity is reversed. Also, here, the reversal of the driving torques of the front wheels 11 and the rear wheels 13 is performed when the lifted position of the middle wheels 12 reaches near the highest point. However, the present invention is not limited to this. The reversal of the driving torques of the front wheels 11 and the rear wheels 13 may be performed so that the middle wheels 12 are reversed and lowered after being lifted.

[0027] FIG. 3c is a left side view showing the operation of lifting the front wheels in the rocker bogie vehicle 1 according to an embodiment of the present invention. As shown in FIG. 3c from the state of FIG. 3b, by driving the two front wheels 11 and the two middle wheels 12 for forward movement and the two rear wheels 13 for backward movement, the middle wheels 12 that have been lifted by releasing the elastic energy accumulated by stretching the spring 6 from the neutral position of the bogie link 2 descend and come into contact with the ground. Then, with the addition of the forward drive of the middle wheels, the two front wheels 11 are lifted. In this way, the rocker bogie vehicle 1 performs a lifting operation on the two front wheels 11, and the two front wheels 11 climb onto the step. The climbing of the two front wheels 11 onto the step may be detected by an image sensor, a gyro sensor, an acceleration sensor, an inertial measurement device, etc., and is not limited to a specific means. After the two front wheels 11 climb onto the step, by driving the two rear wheels 13 for forward movement, the rocker bogie vehicle 1 moves forward by driving all of the two front wheels 11, the two middle wheels 12, and the two rear wheels 13 for forward movement, and crosses the step.

[0028] By controlling each of the six drive wheels as described above, rotational torque can be generated at the joint point 21 to lift the two front wheels 11 and the two middle wheels 12 of the bogie link 2. By lifting the two front wheels 11 of the bogie link 2, the two front wheels 11 can climb onto the step, and high step-crossing performance can be achieved.

[0029] As described above, by independently controlling the driving torque of each of the six wheels of the six-wheel rocker bogie vehicle 1, the rocker bogie vehicle 1 operates to lift the two front wheels 11 of the bogie link 2. In addition, since elastic energy is added by the tension mechanism of the spring 6 connected to each of the joint points 21 of the bogie link 2, the bogie link 2 is likely to vibrate, and it becomes possible to operate so as to lift the two front wheels 11 of the bogie link 2. In this way, by lifting the two front wheels 11 and placing the two front wheels 11 on the step to be traversed, the frictional force of the two front wheels 11 and the frictional force of the middle wheel 12 enable the two front wheels 11 to exert a step traversing performance that exceeds the traversing limit due to the frictional force between the floor surface and the step surface when the two front wheels 11 traverse the step.

[0030] In addition, a pair of rocker bogie mechanisms are connected at the joint point 21 on both sides of the rocker bogie vehicle 1, and motors for the two front wheels 11 and the two middle wheels 12 are arranged. As a result, the bogie link 2 can vibrate back and forth around the joint point 21. By further strengthening the vibration with the spring 6, the strengthened elastic energy is applied to the bogie link 2. Therefore, the rocker bogie vehicle 1 does not include a motor for lifting on the bogie link 2. When the rocker bogie vehicle 1 traverses a step, the two front wheels 11 can be lifted for a step with a height greater than the diameter of the two front wheels 11. Therefore, according to the present embodiment, without providing a lifting motor on the bogie link 2, a small, lightweight, and simple configuration is achieved. Furthermore, elastic energy is applied by vibration when the front wheels are lifted, and this elastic energy is added as an assisting force to climb over, thereby realizing a rocker bogie vehicle 1 with improved step traversing performance.

[0031] Note that when the offset angle described above is set to 0, the spring 6 is in a balanced position with the front wheel 11, the middle wheel 12, and the rear wheel 13 in contact with the ground. When set in this way, the spring 6 maintains the vibration energy. Also, when the offset angle is increased positively, for example, to 20°, elastic energy is stored in the spring 6 with the front wheel 11, the middle wheel 12, and the rear wheel 13 in contact with the ground. When set in this way, the spring 6 generates an assisting force when lifting the front wheel 11. When the frictional force on the vertical surface of the step is low, the front wheel 11 can be lifted high and placed on the step. Conversely, if the offset angle is set to a negative angle, for example, -20°, the balance position will be closer to the middle wheel lifting support, and the spring 6 can generate an assisting force when lifting the middle wheel 12. In the rocker bogie vehicle 1 of the present embodiment, it is preferable to appropriately set the offset angle according to the driving environment, the center of gravity position, the inclination of the driving surface with respect to the gravitational direction, or the ascending and descending direction of the step, etc.

[0032] In the present embodiment, it is assumed that the grounding surface of the rocker bogie vehicle 1 is uneven, and the case where independent control is performed for each of the six wheels of the rocker bogie vehicle 1 has been described. However, the present invention is not limited to this. When a step is detected in the traveling destination and the rocker bogie vehicle is in a state facing the step, the control of the two front wheels 11 may not be independent of each other, the control of the two middle wheels 12 may not be independent of each other, and the control of the two rear wheels 13 may not be independent of each other.

[0033] Also, in the present embodiment, the spring 6 has been illustrated and described as an elastic body. However, the present invention is not limited to this. As the elastic body, rubber may be used instead of the spring 6, and a configuration in which elastic energy is accumulated by stretching this rubber may be adopted. Alternatively, as the elastic body, an air cylinder may be used instead of the spring 6, and a configuration in which the air cylinder is extended, that is, the piston of the air cylinder is pulled, so that the air in the air cylinder is compressed and elastic energy is accumulated may be adopted.

[0034] Alternatively, as the elastic body, a torsion spring disposed at the joint point 21 may be used instead of the spring 6. FIG. 5 is a diagram showing a form in which a torsion spring 6A is used as an elastic body in an embodiment of the present invention. As shown in FIG. 5, the torsion spring 6A is fixed to each of the bogie link 2 and the rocker link 3 at the joint point 21. When the torsion spring 6A is twisted around the joint point 21, elastic energy is accumulated. Alternatively, as the elastic body, a torsion bar disposed at the joint point 21 may be used instead of the spring 6. In this case, elastic energy may be accumulated when the torsion bar is twisted around the joint point 21.

[0035] Note that the present invention is not limited to the above-described embodiments, and also includes various modified examples in which components are added, deleted, or converted with respect to the above-described configurations.

Explanation of Reference Numerals

[0036] 1, 1a Rocker bogie vehicle 11, 11’ Front wheels 110 Front wheel axle 12, 12’ Middle wheels 120 Middle wheel axle 13 Rear wheel 130 Rear wheel axle 2, 2’ Bogie link 21 Joint point 3, 3a Rocker link 5 Body 6, 6’ Spring 6A Torsion spring 61 First end 62 Second end

Claims

1. A rocker bogie vehicle with a total of six wheels, with a pair of front wheels, a pair of middle wheels, and a pair of rear wheels on the left and right, a bogie link to which the front wheels and the center wheels are journalled; a rocker link to which the bogie link is connected and to which the rear wheels are journalled; A main body connected to the rocker link; An elastic body disposed between the bogie link and the main body or the rocker link, The bogie link is capable of vibrating back and forth around a joint point connected to the body or the rocker link; The elastic body accumulates elastic energy by the vibration of the bogie link in response to the backward drive of the front wheels and the middle wheels and the forward drive of the rear wheels, and when the front wheels and the middle wheels switch to forward drive and the rear wheels switch to reverse drive, the elastic energy is released to swing up the front wheels, a rocker bogie vehicle.

2. The drive directions of the front wheels, the middle wheels, and the rear wheels are reversed at a predetermined timing, and the elastic body is stretched from the neutral position of the bogie link, and the elastic energy is accumulated and released, thereby swinging up the front wheels or the middle wheels. The rocker bogie car described in claim 1.

3. A method for driving a rocker bogie vehicle according to claim 1 or 2, Moving forward with the front wheels, the middle wheels and the rear wheels as forward drive; When a step is detected in the traveling direction, the front wheels and the middle wheels are driven in reverse to swing up the middle wheels; In a state where the middle wheel is not on the ground, the front wheels are driven forward, the middle wheels are driven forward, and the rear wheels are driven backward, thereby swinging up the bogie link so that the front wheels are swung up when the middle wheel touches the ground; When the front wheels run over the step, the rear wheels are driven forward to move the rocker bogie car forward and traverse the step. A driving method for a rocker bogie car.

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