Running device

Provided is a running device including a frame (11) and a first wheel part (15) and a second wheel part (35) arranged with an appropriate distance therebetween along a running direction (R). The first wheel part (15) includes a first left support arm (17) and a first right support arm (26) arranged on the frame (11) in a manner to be swingable within a plane extending along the running direction (R). The second wheel part (35) includes a second support arm (36) arranged on the frame (11) in a manner to be swingable within a plane perpendicular to the running direction (R). The first left support arm (17) has first left wheels (19, 21) respectively on both sides thereof, and the first right support arm (26) has first right wheels (28, 30) respectively on both sides thereof. The second support arm (36) has a second left wheel (38) and a second right wheel (40) respectively on both sides thereof.

TECHNICAL FIELD

The present invention relates to a running device arranged on a running vehicle such as an automatic guided vehicle.

BACKGROUND ART

For example, in a manufacturing system called FMS (Flexible Manufacturing System), machine tools are arranged appropriately in a plant and an automatic guided vehicle (running vehicle) is used to deliver a workpiece to be machined, a tool, etc. to each machine tool and also used to collect a machined workpiece, a used tool, etc. from each machine tool. This manufacturing system realizes an unmanned and automated production.

A known example of the automatic guided vehicle is disclosed in Patent Literature 1 listed below. This automatic guided vehicle has a distance measurement device that rotationally drives a light projector projecting a light and outputs distance measurement data based on receipt of a reflected light from an object to be measured, a map generator that generates map information based on the distance measurement data, and an obstacle sensor that senses an obstacle.

A typical running device of an automatic guided vehicle has a frame, a first driven wheel part, a drive wheel part, and a second driven wheel part. The first driven wheel part, the drive wheel part, and the second driven wheel part are arranged at appropriate intervals along the running direction and connected to the frame. The first driven wheel part and the second driven wheel part each include left and right driven wheels, and the drive wheel part includes left and right drive wheels. The automatic guided vehicle runs by rotation of the left and right drive wheels, and the running direction of the automatic guided vehicle is controlled by controlling the numbers of rotations of the left and right drive wheels.

In using this automatic guided vehicle, the automatic guided vehicle is first operated, for example, by manual operation, to cause the automatic guided vehicle to run in a plant building, during which planar map information that defines an inner profile of the plant building and outer profiles of machine tools and other devices arranged in the plant building is generated by the map generator based on the distance measurement data measured by the distance measurement device.

Further, the automatic guided vehicle identifies the current position of itself (self position) in the plant building based on the distance measurement data measured by the distance measurement device and the map information previously generated by the map generator. Thus, the automatic guided vehicle autonomously runs tracklessly along a predetermined path based on the plant-building map information and the self position information to perform the delivery of workpieces and tools.

An automatic guided vehicle does not always run in a plant building having only a flat area, but in some cases, runs in a plant building having not only a flat area but also an area with some bumps and dips. Further, in the case of using an autonomously running automatic guided vehicle, the running path for the automatic guided vehicle is sometimes set in an intentionally formed stepped area.

In the case where the above-described automatic guided vehicle runs in an area with bumps and dips or in an intentionally formed stepped area, it is possible that the drive wheels leave the ground and cannot come into contact with the ground surface when the first driven wheel part or the second driven wheel part runs onto a bump or a step. In such a case, the automatic guided vehicle loses its thrust force and goes out of control, so that the automatic guided vehicle cannot continue running.

In view of these circumstances, a running device as disclosed in Patent Literature 2 listed below has been proposed. This running device has a center frame and a pair of running parts (rocker-bogie mechanisms) symmetrically mounted to the center frame. Each running part includes a rocker frame pivotably supported by the center frame, a bogie frame pivotably supported on a first end of the rocker frame, and first, second, and third wheels respectively rotationally supported on a second end of the rocker frame and both ends of the bogie frame. The second wheels are drive wheels that are independent from each other, and the second wheels are each positioned between the associated first and third wheels that are driven wheels.

Between the rocker frames, two stabilizers, which are each constituted by a bar member, are respectively provided between the first ends and between the second ends. The center frame has two pivot support members provided thereon that respectively support the bar members constituting the stabilizers such that the bar members are pivotable. The rocker frames each have support members respectively provided on the first and second ends thereof that each support the corresponding bar member such that the bar member is slidable.

The configuration in which the pair of rocker-bogie mechanisms are respectively pivotably supported on both sides of the center frame enables the running device to run while maintaining a stable posture even when one of the rocker-bogie mechanisms climbs over a step or climbs on or down a step, and also enables the center frame to maintain its own horizontality even when the rocker-bogie mechanisms climb over a step or climb on or down a step. Further, increase of the overall height of this running device is suppressed because the rocker frames constituting the rocker-bogie mechanisms extend horizontally, so that stable running of the running device is ensured.

CITATION LIST

Patent Literature

Patent Literature 1: Japanese Unexamined Patent Application Publication No. 2019-8359Patent Literature 2: Japanese Unexamined Patent Application Publication No. 2017-222297

SUMMARY OF INVENTION

Technical Problem

Although the above-described running device disclosed in Patent Literature 2 provides the above-described advantages, it has a complicated structure since the bogie frames are pivotably supported on the first ends of the rocker frames that are also pivotably supported by the center frame, and besides, between the rocker frames, the two stabilizers each constituted by a bar member are respectively provided between the first ends and between the second ends, which causes an increase in equipment cost.

In the field of equipment such as plant equipment, cost reduction is always desired. The above-described running device is no exception, that is to say, cost reduction is desired for the above-described running device.

The present invention has been achieved in view of the above-described circumstances, and an object of the invention is to provide a running device which has a simple structure and therefore can be manufactured at a low cost.

Solution to Problem

To solve the above-described problem, the present invention provides a running device arranged on a running vehicle, including:

a frame; and

a first wheel part and a second wheel part arranged with an appropriate distance therebetween along a running direction and connected to the frame,

the first wheel part including a first left support arm and a first right support arm respectively disposed on a left side and a right side with respect to the running direction and each connected to the frame in a manner to be swingable within a vertical plane extending along the running direction,

the second wheel part including a second support arm connected to the frame in a manner to be swingable within a vertical plane perpendicular to the running direction,

the first left support arm having a first left wheel on each of both sides of a center of swinging thereof, the first left wheels being each supported in a manner to be rotatable about a horizontal axle perpendicular to the running direction,

the first right support arm having a first right wheel on each of both sides of a center of swinging thereof, the first right wheels being each supported in a manner to be rotatable about a horizontal axle perpendicular to the running direction,

the second support arm having a second left wheel and a second right wheel respectively on both sides of a center of swinging thereof, the second left wheel and the second right wheel being each supported in a manner to be rotatable about an axle perpendicular to the running direction,

the center of swinging of the first left support arm being positioned on a line connecting centers of the two first left wheels,

the center of swinging of the first right support arm being positioned on a line connecting centers of the two first right wheels.

In the thus-configured running device, the first left support arm and first right support arm constituting the first wheel part are each swingable within a vertical plane extending along the running direction, and the second support arm constituting the second wheel part is swingable within a vertical plane perpendicular to the running direction. Further, the frame is supported by six wheels, namely, the two first left wheels arranged on both sides of the first left support arm, the two first right wheels arranged on both sides of the first right support arm, and the second left wheel and second right wheel arranged on both sides of the second support arm.

Therefore, when one of the first left wheels arranged on both sides of the first left support arm runs onto a step on the ground, the first left support arm swings so that the difference in level of the step is absorbed and all the wheels of the running device are thereby kept in contact with the floor surface. Further, also when one of the first right wheels arranged on both sides of the first right support arm runs onto a step on the ground, the first right support arm swings so that the difference in level of the step is absorbed and all the wheels of the running device are thereby kept in contact with the ground surface. Furthermore, also when one of the second left wheel and second right wheel arranged on both sides of the second support arm runs onto a step on the ground, the second support arm swings so that the difference in level of the step is absorbed and all the wheels of the running device are thereby kept in contact with the ground surface.

Thus, with the running device according to the present invention, when a wheel of the running device runs onto a step on the ground, the corresponding one of the first left support arm, first right support arm, and second support arm swings so that the difference in level of the step is absorbed and all the wheels of the running device are thereby kept in contact with the ground surface, which enables the running device to run stably.

Further, this running device is configured such that the wheels are supported by three swingably-supported support arms, namely, the first left support arm, the first right support arm, and the second support arm. Therefore, this running device has a simple structure as compared with the conventional running device and therefore can be manufactured at a low cost.

The running device according to the present invention may have a configuration in which:

the second support arm of the second wheel part has a third left support arm and a third right support arm respectively on both sides of the center of swinging thereof, the third left support arm and the third right support arm being each swingable within a plane extending along the running direction;

the third left support arm has the second left wheel on each of both sides of a center of swinging thereof, the second left wheels being each supported in a manner to be rotatable about an axle perpendicular to the running direction; and

the third right support arm has the second right wheel on each of both sides of a center of swinging thereof, the second right wheels being each supported in a manner to be rotatable about an axle perpendicular to the running direction.

In the thus-configured running device, the frame is supported by eight wheels in total, namely, the two first left wheels arranged on the first left support arm, the two first right wheels arranged on the first right support arm, the two second left wheels arranged on the third left support arm, and the two second right wheels arranged on the third right support arm. Further, besides the swinging motions of the first left support arm, first right support arm, and second support arm, the swinging motions of the third left support arm and third right support arm are also capable of absorbing a difference in level on the ground. Therefore, the running device is capable of absorbing more various types of unevenness formed on the ground.

Further, the running device according to the present invention may have a configuration in which at least one of the first left wheels and second left wheel or wheels and at least one of the first right wheels and second right wheel or wheels are drive wheels.

Furthermore, each of the wheels other than the drive wheels may be composed of a universal wheel. Alternatively, each of the wheels other than the drive wheels may be composed of an omni wheel.

Advantageous Effects of Invention

As described above, with the running device according to the present invention, when a wheel of the running device runs onto a step on the ground, the corresponding one of the first left support arm, first right support arm, and second support arm swings so that the difference in level of the step is absorbed and all the wheels of the running device are thereby kept in contact with the ground surface, which enables the running device to run stably.

Further, the running device according to the present invention is configured such that the wheels are supported by three swingably-supported support arms, namely, the first left support arm, the first right support arm, and the second support arm. Therefore, the running device has a simple structure as compared with the conventional running device and therefore can be manufactured at a low cost.

DESCRIPTION OF EMBODIMENTS

Hereinafter, a specific embodiment of the present invention will be described with reference to the drawings.

As illustrated inFIGS.1and2, an automatic guided vehicle1according to this embodiment has a running device10, a support base2having a rectangular shape in plan view and arranged on the running device10, sensors5respectively arranged on three corners of an upper surface of the support base2, a cover3surrounding the support base2, and a liftable table4having a rectangular shape in plan view and arranged on the support base2in a manner to be liftable up/down. Note that the liftable table4lifts up/down by being driven by a lifting mechanism that is not illustrated in the drawings. The running device10and the lifting mechanism (not illustrated) are controlled by a controller that is not illustrated in the drawings.

As illustrated inFIGS.2to4, the running device10has a frame11and a first wheel part15and a second wheel part35respectively arranged on the front side and the rear side with an appropriate distance therebetween along the running direction (the direction indicated by arrow R) and connected to the frame11. Note that the frame11is formed to have, in plan view, spaces cut out appropriately for arranging necessary structural objects therein and have a hollow interior for the sake of weight reduction.

The first wheel part15consists of a first left wheel unit16and a first right wheel unit25respectively disposed on the left side and the right side with respect to the running direction. The first left wheel unit16includes a first left support arm17arranged on a left side surface of the frame11and first left wheels19,21respectively supported on both ends of the first left support arm17in a manner to be rotatable about horizontal axles20,22perpendicular to the running direction.

The first right wheel unit25includes a first right support arm26arranged on a right side surface of the frame11and first right wheels28,30respectively supported on both ends of the first right support arm26in a manner to be rotatable about horizontal axles29,31perpendicular to the running direction.

The first right support arm26is supported by a support shaft27arranged on the right side surface of the frame11so as to be swingable in the directions indicated by arrow D-E inFIG.3within a vertical plane extending along the running direction. Similarly, the first left support arm17is supported by a support shaft18arranged on the left side surface of the frame11so as to be swingable in directions identical to the arrow D-E directions within a vertical plane extending along the running direction.

Note that, in this embodiment, the first left wheel19and the first right wheel28, which are disposed on the front side in the running direction, are driven wheels and the first left wheel21and the first right wheel30, which are disposed on the rear side in the running direction, are drive wheels. The first left wheel21is connected to a motor23via a decelerator24arranged on the first left support arm17so that the first left wheel21rotates by being driven by the motor23. Similarly, the first right wheel30is connected to a motor32via a decelerator33arranged on the first right support arm26so that the first right wheel30rotates by being driven by the motor32.

The second wheel part35includes a second support arm36arranged on the rear side of the frame11in the running direction. The second support arm36is supported by a support shaft37arranged on a rear side surface of the frame11so as to be swingable in the directions indicated by arrow F-G inFIG.4within a vertical plane perpendicular to the running direction. Further, the second support arm36has a second left wheel38and a second right wheel40respectively on both ends thereof that are respectively supported in a manner to be rotatable about horizontal axles39,41perpendicular to the running direction. Note that the second left wheel38and the second right wheel40are driven wheels.

The first left wheel19, the first right wheel28, the second left wheel,38, and the second right wheel40have the same configuration and they are each composed of an omni wheel. Although the following description is directed to the first left wheel19as a representative one that is illustrated inFIGS.5and6, the first right wheel28, the second left wheel38, and the second right wheel40are also configured in the same manner. Note that the first left wheel21and the first right wheel30are each composed of an ordinary wheel; therefore, detailed description of them is omitted.

As illustrated inFIGS.5and6, the first left wheel19consists of a body19ahaving a center hole19bformed in the center thereof for inserting the axle20therein, rollers19c,19d,19earranged on the right side of the body19ainFIG.6, and rollers19f,19g,19harranged on the left side of the body19ainFIG.6. The body19ahas a disk-shaped base, and the base has ribs formed on the left and right sides thereof for supporting the rollers19c,19d,19e,19f,19g,19hin vertical planes such that the rollers19c,19d,19e,19f,19g,19hare each rotatable.

The rollers19c,19d,19e,19f,19g,19hhave a drum-like shape with the same curvature and are respectively rotatably supported by support shafts that are supported by the ribs so as to be positioned in vertical planes. The rollers19c,19d,19eare arranged at equal intervals in the circumferential direction of the body19a, and the rollers19f,19g,19hare also arranged at equal intervals in the circumferential direction of the body19a. The rollers19c,19d,19eand the rollers19f,19g,19hare arranged such that they are phase-shifted 60° relative to each other in the circumferential direction.

Further, the rollers19c,19d,19eare arranged such that outer surfaces thereof are located on the same arc in a vertical plane including their support shafts. Similarly, the rollers19f,19g,19hare arranged such that outer surfaces thereof are located on the same arc in a vertical plane including their support shafts.

Thus, the first left wheel19is configured such that rotation of the first left wheel19about the axle20advances the first left wheel19in the rotating direction and rotation of each roller19c,19d,19e,19f,19g,19hslides the first left wheel19in a horizontal direction intersecting with the rotating direction and the axle20.

With the automatic guided vehicle1according to this embodiment having the above-described configuration, under control by the controller (not illustrated), the automatic guided vehicle1runs in accordance with driving of the motors23,32and the liftable table4lifts up/down in accordance with driving of the lifting mechanism.

In the case where the automatic guided vehicle1runs in a plant, if, for example, the first right wheel28runs onto a step S provided in the plant as shown inFIG.7, the first right support arm26swings in the arrow D direction, whereby the first right wheel30as a drive wheel as well as the first left wheels19,21, the first right wheel28, the second left wheel38, and the second right wheel40are all kept in contact with the ground surface. On the other hand, if the first right wheel30runs onto the step S, the first right support arm26swings in the arrow E direction, whereby the first left wheels19,21, the first right wheels28,30, the second left wheel38, and the second right wheel40are all kept in contact with the ground surface.

Similarly, if the first left wheel19runs onto the step S, the first left support arm17swings in the arrow D direction, whereby the first left wheel21as a drive wheel as well as the first left wheel19, the first right wheels28,30, the second left wheel38, and the second right wheel40are all kept in contact with the ground surface. On the other hand, if the first left wheel21runs onto the step S, the first left support arm17swings in the arrow E direction, whereby the first left wheels19,21, the first right wheels28,30, the second left wheel38, and the second right wheel40are all kept in contact with the ground surface.

Further, if the second right wheel40runs onto the step S as shown inFIG.8, the second support arm36swings in the arrow F direction, whereby the first left wheels19,21, the first right wheels28,30, the second left wheel38, and the second right wheel40are all kept in contact with the ground surface. On the other hand, if the second left wheel38runs onto the step S, the second support arm36swings in the arrow G direction, whereby the first left wheels19,21, the first right wheels28,30, the second left wheel38, and the second right wheel40are all kept in contact with the ground surface.

As described above, with the automatic guided vehicle1according to this embodiment, when one or more of the first left wheels19,21, first right wheels28,30, second left wheel38, and second right wheel40run onto a step S on the ground, the corresponding one or ones of the first left support arm17, first right support arm26, and second support arm36swing so that the difference in level of the step S is absorbed and all the wheels are thereby kept in contact with the ground surface, which enables the automatic guided vehicle1to run stably.

Further, the running device10of the automatic guided vehicle1is configured such that the first left wheels19,21, the first right wheels28,30, and the second left and right wheels38,40are respectively supported by the first left support arm17, the first right support arm26, and the second support arm36that are swingably supported. Therefore, the running device10has a simple structure as compared with the conventional running device and therefore can be manufactured at a low cost.

Further, the swinging motions of the first left support arm17, first right support arm26, and second support arm36also provide a shock-absorbing effect; therefore, it is not necessary to provide a suspension that is conventionally required. Also in this respect, the running device10has a simple structure as compared with the conventional running device and therefore can be manufactured at a low cost.

Further, in the running device10according to this embodiment, the first left wheel19, the first right wheel28, the second left wheel38, and the second right wheel40, which are driven wheels, are each composed of an omni wheel; therefore, when the running direction of the automatic guided vehicle1that is running in a predetermined direction needs to be changed to another direction with any of these wheels in contact with a step, the running direction can be changed smoothly. For example, in the case where the running direction of the automatic guided vehicle1is changed with the second right wheel40in contact with a step S′ as shown inFIG.9, the running direction can be changed without any special preliminary operation.

A universal wheel60as illustrated inFIGS.10and11is conventionally known as a driven wheel. This universal wheel60consists of, for example, a base plate61to be attached to a lower surface of the first left support arm17, first right support arm26, or second support arm36, a rotating plate62mounted to a lower surface of the base plate61, support plates63,63arranged with a predetermined distance therebetween on a lower surface of the rotating plate62to extend down from the lower surface of the rotating plate62, a support shaft65supported by the support plates63,63, and a wheel64rotatably supported by the support shaft65between the support plates63,63. This universal wheel60is configured such that the wheel64is turned in a horizontal plane by horizontal rotation of the rotating plate62and the running direction of the wheel64is changed by this turning of the wheel64.

With this universal wheel60, the changing of the running direction of the universal wheel60requires turning of the wheel64to a desired direction and also requires a distance for movement for performing the turning. Therefore, for example, in the case where the running direction of the automatic guided wheel1is changed by 90° either to the left or to the right with the wheel64of the universal wheel60in contact with the step S′ similarly to inFIG.9, the step S′ obstructs the turning of the wheel64; consequently, the running direction of the automatic guided vehicle1cannot be changed.

Hereinbefore, a specific embodiment of the present invention has been described. However, the present invention is not limited to the above-described embodiment and can be implemented in other manners.

For example, the running device according to the present invention may be configured as illustrated inFIG.12. The thus-configured running device10′ has a second wheel part35′ instead of the second wheel part35in the above-described embodiment. In this respect, the running device10′ differs in configuration from the above-described running device10. The other components of the running device10′ are the same as those of the running device10. Therefore, inFIG.12, the same components are denoted by the same reference numerals as used for the running device10.

As illustrated inFIG.12, the second wheel part35′ includes a third left support arm45and a third right support arm49respectively arranged on both ends of the second support arm36. The third left support arm45has second left wheels38,47respectively supported on both ends thereof in a manner to be rotatable about horizontal axles39,48perpendicular to the running direction. The third right support arm49has second right wheels40,51respectively supported on both ends thereof in a manner to be rotatable about horizontal axles41,52perpendicular to the running direction.

In the thus-configured running device10′, the frame11is supported by eight wheels in total, namely, the two first left wheels19,21arranged on the first left support arm17, the two first right wheels28,30arranged on the first right support arm26, the two second left wheels38,47arranged on the third left support arm45, and the two second right wheels40,51arranged on the third right support arm49. Further, besides the swinging motions of the first left support arm17, first right support arm26, and second support arm36, the swinging motions of the third left support arm45and third right support arm49are also capable of absorbing a difference in level on the ground. Therefore, the running device10′ is capable of absorbing more various types of unevenness formed on the ground.

In the above-described running devices10and10′, the first left wheel21and the first right wheel30are drive wheels. However, the present invention is not limited to this configuration, and a configuration is possible in which wheels other than the first left wheel21and the first right wheel30are drive wheels. For example, the running device10may have a configuration in which either of the first left wheel19and second left wheel38and either of the first right wheel28and second right wheel40are drive wheels. Similarly, the running device10′ may have a configuration in which the first left wheel19and either of the second left wheels38,47are drive wheels and the first right wheel28and either of the second right wheels40,51are drive wheels.

Further, in the above-described embodiments, each of the wheels as a driven wheel is composed of an omni wheel. However, the present invention is not limited to this configuration. Although the disadvantage as described above is supposed to occur in changing the running direction, the universal wheel60as illustrated inFIGS.10and11may be used for the wheels as driven wheels because it also has advantages, such as that it is relatively inexpensive.

As already mentioned above, the foregoing description of the embodiments is not limitative but illustrative in all aspects. One skilled in the art would be able to make variations and modifications as appropriate. The scope of the invention is not defined by the above-described embodiments, but is defined by the appended claims. Further, the scope of the invention encompasses all modifications made from the embodiments within a scope equivalent to the scope of the claims.

REFERENCE SIGNS LIST