CN110371215B

CN110371215B - Automatic guide transport vehicle

Info

Publication number: CN110371215B
Application number: CN201810955507.0A
Authority: CN
Inventors: 王佳
Original assignee: Beijing Jingdong Qianshi Technology Co Ltd
Current assignee: Beijing Jingdong Qianshi Technology Co Ltd
Priority date: 2018-08-21
Filing date: 2018-08-21
Publication date: 2021-04-30
Anticipated expiration: 2038-08-21
Also published as: CN110371215A

Abstract

The invention discloses an automated guided vehicle (1), comprising: a chassis (7); and left and right guide wheels (4) rotatably connected to the chassis. The automated guided vehicle further includes a guide wheel steering range control mechanism that is fixed to the chassis and includes a reverse movement generating mechanism (10) capable of moving the limit adjustment members in opposite directions to limit the steering ranges of the left and right guide wheels, respectively, and limit adjustment members (3) for the left and right guide wheels, respectively. The invention restrains the whole vehicle from deviating caused by the slipping of one driving wheel, thereby preventing the occurrence of operation faults.

Description

Automatic guide transport vehicle

Technical Field

The invention relates to the field of warehouse logistics, in particular to an Automatic Guided Vehicle (AGV).

Background

AGV carts are known to have been widely used during warehouse management or article transport. The function of the steerable wheels of current AGV vehicles is primarily to carry the overall weight and assist in steering. However, there is no mechanism for limiting the steering range of motion of the steerable wheels for an AGV vehicle. The reason for this is that, on the one hand, some AGV classes (e.g., light-duty AGVs) do not have high requirements on this point, such as friction of the guide wheels against the ground, resistance of the drive wheels, etc.; on the other hand, many AGV providers do not want to invest excessive costs in this regard.

However, in the use application, when the ground surface is accumulated with a large amount of dust due to a low arrival frequency of a part of the warehouse area, and a part of the ground surface is wet due to water or oil scattering during the work, or a part of the ground surface is uneven, the ground friction is reduced or the positive pressure is insufficient.

It has been found that there are at least the following problems in the prior art: for a common polyurethane rubber-coated wheel, when the friction force of the ground on site is reduced or the positive pressure is insufficient, one driving wheel of a heavy-load AGV slips to cause the whole AGV to deviate, so that operation faults occur. Therefore, an AGV with special utility requirements, such as a heavy-duty AGV, requires limiting the steering range of motion of the steerable wheels to avoid failure due to stalling of the motor.

Accordingly, there is a need for improvements to existing AGVs.

Disclosure of Invention

An object of the present invention is to provide an AGV capable of suppressing deviation of a whole vehicle due to slipping of one driving wheel, thereby preventing occurrence of an operation failure.

To achieve the above object, according to one aspect of the present invention, there is provided an automated guided vehicle including: a chassis; and left and right guide wheels rotatably connected to the chassis; the automated guided vehicle further includes a guide wheel steering range control mechanism fixed to the chassis and including a reverse motion generating mechanism capable of moving the limit adjustment member of the left guide wheel in a direction toward the left guide wheel and the limit adjustment member of the right guide wheel in a direction toward the right guide wheel, and limit adjustment members for the left guide wheel and the right guide wheel, respectively, to limit the steering ranges of the left guide wheel and the right guide wheel, respectively.

According to the above configuration, it is possible to ensure that the vehicle body continues to travel in the moving direction when one driving wheel of the AGV slips, thereby eliminating frequent operation troubles due to problems that cannot be avoided by the conventional design, such as a change in frictional force between the driving wheel and the ground.

Preferably, the reverse motion generating mechanism comprises a motor and a set of positive and negative lead screws, the motor drives the screws of the set of positive and negative lead screws, and the limit adjusting member is fixed to the nuts of the set of positive and negative lead screws.

According to the above configuration, the automated guided vehicle is realized at a low cost and in a compact spatial arrangement.

Preferably, the motor drives the screws of the set of positive and negative screws through a synchronous belt.

Preferably, the motor is connected with the screw rods of the group of positive and negative screw rods through a coupler.

Preferably, the reverse motion generating mechanism includes a motor and a timing belt, the motor drives the timing belt to rotate, and the limit adjusting members are disposed on two linear sections of the timing belt for performing linear motion.

Preferably, the reverse motion generating mechanism includes a motor and two sets of rack and pinion mechanisms, a gear of one of the two sets of rack and pinion mechanisms is connected to an output shaft of the motor, a gear of the other set of rack and pinion mechanisms is connected to the output shaft of the motor via another gear, and the limit adjusting member is fixed on a rack of the two sets of rack and pinion mechanisms.

According to the above configuration, the limit of the guide wheel of the automated guided transporting vehicle is realized with high accuracy.

Preferably, the automated guided vehicle further comprises a proximity sensor for limiting an extreme range of motion of the limit adjustment member.

Preferably, a stopper member is provided, which is fixed to wheel seats of the left and right guide wheels, against which the limit adjustment member abuts when limiting the left and right guide wheels.

Preferably, the limit adjusting member directly abuts against the wheel seats of the left and right guide wheels when limiting the left and right guide wheels.

According to the above configuration, the limit of the guide wheel of the automated guided transporting vehicle is realized at a low cost.

Preferably, the number of limit adjustment members of the left guide wheel and/or the right guide wheel is two, and the two limit adjustment members are configured to have a fork form.

According to the above configuration, the guide wheels of the automated guided vehicle are kept in a specific direction such as the front-rear direction as much as possible.

Preferably, the automated guided vehicle includes two guide wheel steering range control mechanisms for a set of front guide wheels and a set of rear guide wheels, respectively; a set of front guide wheels comprising: a left front wheel and a right front wheel arranged on the chassis; a set of rear guide wheels comprising: and the left rear wheel and the right rear wheel are arranged on the chassis.

According to the above configuration, the overall limitation of the steering range of the guide wheels of the automated guided transporting vehicle is achieved.

Preferably, the automated guided vehicle includes a drive train that is a dual motor differential steering train.

According to the above structure, the whole vehicle is stable and does not shake when the driving gear train rotates, the lifting movement can be realized when the driving gear train rotates, and the cost of one motor can be reduced.

According to another aspect of the invention, there is provided a use of the automated guided vehicle according to the invention in warehouse logistics.

Further effects of the above-mentioned non-conventional alternatives will be described below in connection with the embodiments.

Drawings

The drawings are included to provide a better understanding of the invention and are not to be construed as unduly limiting the invention. Wherein:

FIG. 1a is a bottom view of a portion of an AGV according to an embodiment of the present invention;

FIG. 1b is a front view of a portion of an AGV according to an embodiment of the present invention;

FIG. 1c is an overhead view of a portion of an AGV according to an embodiment of the present invention with the chassis removed;

FIG. 2 is a bottom view of a full chassis of an AGV according to an embodiment of the present invention, illustrating the use of a combination of the drive train and guide wheel steering range control mechanisms of the AGV.

Fig. 3 shows an alternative embodiment of the invention in which a timing belt is used instead of a lead screw.

Detailed Description

Exemplary embodiments of the present invention will hereinafter be described in conjunction with the appended drawings, wherein various details of the embodiments of the present invention are included to assist understanding, and they are to be considered exemplary only, and not limiting in any way. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the invention. Also, descriptions of well-known functions and constructions are omitted in the following description for clarity and conciseness.

FIGS. 1a-1c illustrate a portion of an AGV according to an embodiment of the present invention including a pair of front/rear guide wheels, where FIG. 1a is a bottom view of a portion of the AGV according to an embodiment of the present invention; FIG. 1b is a front view of a portion of an AGV according to an embodiment of the present invention; and FIG. 1c is an overhead view of a portion of an AGV according to an embodiment of the present invention with the floor of the AGV removed for ease of viewing and understanding. Various guidance methods for AGVs are known, such as laser guidance and two-dimensional code guidance. When the two-dimensional code guide manner is adopted, a plurality of two-dimensional codes are pasted on the ground and spaced apart at a certain distance. The AGV may move in a controlled manner from one two-dimensional code to another to complete the transport of the item.

As shown in FIG. 1b, AGV1 includes chassis 7 and guide wheels 4. The chassis 7 constitutes a support floor for the AGV, on the surface of which chassis 7 items to be transported can be placed. The guide wheels 4 are steerable over a range of angles α and are rotatably mounted in a known manner in wheel mounts 8, which wheel mounts 8 are pivotally mounted on the chassis 7. Thereby, the guide wheel assembly of the guide wheel 4 and the wheel seat 8 can be freely pivoted in the range of the angle α relative to the chassis 7, whereby the guide wheel 4 can be freely pivoted relative to the chassis 7, whereby the guiding of the guide wheel 4 is achieved.

The AGV1 according to this embodiment also includes two guide wheel steering range control mechanisms for the two front and two rear guide wheels, respectively, and is secured to the chassis 7. For simplicity, only one steerable wheel range control mechanism is shown in FIGS. 1a-1 c. Each of the guide wheel steering range control mechanisms includes a reverse movement generating mechanism 10 capable of moving the limit adjustment members 3 of the left and right guide wheels in opposite directions, i.e., the limit adjustment member of the left guide wheel moves in a direction toward the left guide wheel and the limit adjustment member of the right guide wheel moves in a direction toward the right guide wheel, and limit adjustment members 3 for the left and right guide wheels, respectively, to limit the steering ranges of the left and right guide wheels, respectively.

In the illustrated embodiment, the reverse motion generating mechanism 10 includes a motor 11 and a set of forward and reverse lead screws 2. The specific type of motor 11 is not limited as long as it can provide a rotational motion. As shown in fig. 1a-1c, the motor 11 is fixedly mounted to the chassis 7, for example by means of a bracket 13 mounted to the chassis 7. Each lead screw 2 comprises a screw rod 21 and a nut 22 sleeved on the screw rod 21, and the limit adjusting component 3 is fixed on the nuts 22 of a group of positive and negative lead screws 2. The screws 21 of the two screws 2 are integrally formed, thereby forming an integral screw. When the motor 11 drives the screw 21 to rotate, the nut 22 moves axially along the screw 21, and further drives the limit adjusting member 3 to move axially along the screw 21. Optionally, each lead screw 2 may further include a nut 22 received therein to reduce frictional losses between the nut 22 and the lead screw 21 during axial movement of the nut 22 along the lead screw 21.

A timing belt 12 is provided, one end of which 12 is coupled to an output shaft of the motor 11 and the other end is coupled to a central portion of the integrated screw. Thereby, the motor 11 drives the screws 21 of the pair of forward and reverse screws 2 through the timing belt 12. Thereby, the rotational motion of the output shaft of the motor 11 is transmitted to each lead screw 2 via the timing belt 12.

The coupling between the motor 11 and the lead screw 2 is not limited to the above configuration. For example, a coupling may be provided instead of the timing belt. The output shaft of the motor is connected with a screw 21 of a group of positive and negative screw rods 2 through a coupler.

As shown in fig. 1b, a guide rail 24 is provided on the lower surface of the chassis 7, and the nut 22 can be linearly moved along the guide rail 24. Preferably, the guide rail 24 is internally provided with balls to guide the movement of the nut 22.

As shown in fig. 1a, 1b and 1c, for each guide wheel 4, a set of limit adjustment members 3, i.e. two limit adjustment members 3, is provided. The limit adjustment member 3 has the form of a rod, for example. One end of the two limit adjustment members 3 is fixedly connected to a nut 22 of one lead screw 2, the other end of the two limit adjustment members 3 faces the guide wheel 4, and one set of limit adjustment members 3 has substantially the shape of a fork.

For each guide wheel, a stop member 5 is provided, which stop member 5 is fixed on a wheel seat 8 and has the form of a rod, for example. In the longitudinal direction of the AGV, the stop member 5 extends from one end of the wheel seat towards the other end. The end portions of one set of limit adjusting members 3 can abut against both ends of the stopper member 5 in the longitudinal direction of the AGV, respectively, to be limited. However, the limit structure is not limited thereto. For example, the stop member 5 may not be provided, and the set of limit adjustment members 3 can directly abut against the wheel seat 8 of the guide wheel 4.

In the embodiment shown in the figures, the set of limit-adjusting members 3 is connected to the lower surface of the nut 22, and in the vertical direction, the limit-adjusting members 3 are located between the wheel seat 8 and the chassis 7; the stopper member 5 is fixed on the upper surface of the wheel base 8, and is located outside the wheel base 8 in the AGV width direction. However, the present invention is not limited to the above configuration. Specifically, the limit adjustment member 3 may be attached to a side surface of the nut 22, and the stopper member 5 may be fixed on an upper surface or a side surface of the wheel base 8 on an inner side of the wheel base 8 in the AGV width direction. And, the specific shapes of the limit adjustment member 3 and the stopper member 5 are not limited. The spacing adjustment member 3 and the stop member 5 have substantially the same height so as to abut against each other.

As shown in FIG. 1a, the AGV is also provided with a proximity sensor 6 that is secured to the chassis 7, preferably to the lower surface of the chassis 7. The proximity sensor 6 is configured to provide a distance measurement between the proximity sensor and the nut 22. When the measured distance is less than or equal to the predetermined threshold, the movement of the nut 22 is stopped. The proximity sensor may be a laser position sensor or a confocal sensor. The proximity sensor may also be connected to an image sensor to provide distance data to the image sensor and to display the specific location of the nut 22 on a display.

FIG. 2 is a bottom view of a full vehicle chassis of an AGV according to an embodiment of the present invention showing the drive train of the AGV. As shown in fig. 2, the drive train 9 is a conventional AGV two-motor differential steering train which is connected in a known manner to a bracket 13, to which bracket 13 the chassis 7 is also fixed. The drive train 9 comprises two motors 91 and drive wheels 92 in power connection with each motor 91. The drive wheel is a drive wheel capable of 360 degree rotation. Fig. 2 also shows four wheels as guide wheels 4, namely, a front left wheel 4FL, a front right wheel 4FR, a rear left wheel 4RL, and a rear right wheel 4 RR. As shown, the left and right front wheels 4FL and 4FR are in a freely rotating state in which the limit adjusting member 3 is spaced far from the stopper member 5, respectively, while the left and right rear wheels 4RL and 4RR are in a state to be limited in which the limit adjusting member 3 and the stopper member 5 come gradually close to and finally abut against each other to limit the turning of the guide wheels, specifically, the left and right rear wheels 4RL and 4RR, respectively.

The principle of the turn limit of an AGV according to the present invention is described below.

In the prior art, when an AGV starts to run along a two-dimensional code according to a specific guiding mode, for example, one driving wheel is easy to slip due to the fact that the friction coefficient between a certain position of the ground and the wheels is reduced, so that the whole AGV deviates, and therefore faults occur.

However, according to the present invention, when the control system of AGV1 determines that the AGV is about to start traveling in a certain direction, the guide wheel steering range control mechanism of the AGV is activated. Specifically, the motor 11 is started first; the motor 11 drives the screw 21 of a set of positive and negative lead screws to rotate through a synchronous belt 12 or a coupling (not shown); since the screw direction of the threaded spindle 21 of the threaded spindle is opposite, the two nuts 22 arranged on the one-piece threaded spindle 21 move back along the respective guide rails, i.e. away from one another; the two groups of limit adjusting components 3 respectively connected with the nuts 22 move back to back; when the limit adjustment member 3 approaches or abuts the limit fixing rod 5 or the wheel seat 8, the steering range of the guide wheel 4 is limited or deadened, wherein the adjustment range limit position of the limit adjustment member 3 can be limited by the proximity sensor 6.

Further, when the control system of the AGV1 judges that the AGV is going to turn, the motor rotates in the reverse direction, driving the nuts of the lead screws to move in the opposite direction, whereby the limit adjusting members 3 connected to the nuts move in the opposite direction, i.e., move close to each other; when the distance of the limit adjustment member 3 or the nut 22 from the proximity sensor 6 reaches a predetermined threshold value, the limit adjustment member 3 stops moving, thereby canceling the restriction of the steering range of the guide wheel 4, enabling the guide wheel 4 to freely rotate, and smoothly making a turn.

As described above, the AGV according to the present invention can restrict the steering range of the guide wheels 4 according to the selected travel route, so that the direction of the guide wheels can be directly restricted, i.e., the AGV can travel only in the front-rear direction or the longitudinal direction of the AGV and cannot turn. Because the whole AGV has the weight on the front and rear four guide wheels, even if one driving wheel slips, the guide wheels can not be steered, so that the AGV can continuously run forwards without deviating from the preset running route.

Therefore, a set of simple and reliable mechanisms (such as a motor and a positive and negative lead screw) is used for controlling the steering range of the guide wheel, and the operation fault caused by the slipping of the driving wheel due to field ground factors is effectively prevented.

In addition, as shown in fig. 2, the conventional AGV dual-motor driven differential steering gear train can achieve the following advantages in cooperation with the steerable range control mechanism of the steerable wheel of the present invention: when the driving gear train rotates, the whole vehicle is stable and cannot shake (stable rotation of the driving gear train), lifting motion can be realized when the driving gear train rotates, the cost of one motor can be reduced, and the like.

The automated guided transport vehicle 1 according to the invention is particularly suitable for use in the field of warehouse logistics.

Alternative embodiments

As described above, the reverse motion generating mechanism of the steering range control mechanism of the steerable wheels according to the present invention includes the motor 11 and the set of the positive and negative lead screws 2. However, the present invention is not limited to the above configuration.

Alternatively, a synchronous belt may be used instead of the set of positive and negative screws described above, as shown in FIG. 3. In this embodiment, one end of the timing belt is connected to the motor and the other end is connected to a rotatably mounted gear; and two sets of limit adjustment members are respectively connected to two belt sections of the timing belt which perform linear motion. Therefore, when the motor rotates, the synchronous belt rotates together, and therefore the two groups of limit adjusting members arranged on the two belt sections respectively perform linear motion in opposite directions, so that simultaneous limit of the left guide wheel and the right guide wheel is realized.

Alternatively, a rack and pinion mechanism may be used instead of the set of positive and negative lead screws described above. In this embodiment, two sets of rack and pinion mechanisms are provided, the gears of one set of the rack and pinion mechanisms are directly connected to the motor, while the gears of the other set of the rack and pinion mechanisms are connected to the motor via the other gear, and the respective racks of the two sets of the rack and pinion mechanisms are connected to limit-adjusting members, respectively. Therefore, when the motor rotates, the racks of the two sets of gear rack mechanisms respectively perform linear motion in opposite directions, and therefore the limit adjusting members arranged on the racks respectively perform linear motion in opposite directions, so that simultaneous limit of the left guide wheel and the right guide wheel is realized.

In addition, other various mechanisms for achieving the reverse motion are also contemplated, such as a double cam mechanism, wherein each cam is separately connected (possibly via a linkage) to a corresponding limit adjustment member. When the camshaft rotates, the limiting adjusting components of the left guide wheel and the right guide wheel perform linear motion in opposite directions, so that simultaneous limiting of the left guide wheel and the right guide wheel is realized.

The above-described embodiments are exemplary only, and should not be construed as limiting the scope of the invention in any way. Those skilled in the art will appreciate that various modifications, combinations, sub-combinations, and substitutions are possible, depending on design requirements and other factors. Any modification, equivalent replacement or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An automated guided vehicle (1) comprising:

a chassis (7); and

left and right guide wheels (4) rotatably connected to the chassis;

characterized by further comprising a guide wheel steering range control mechanism fixed to the chassis (7) and comprising a reverse motion generating mechanism (10) capable of moving the limit adjustment member (3) of the left guide wheel in a direction towards the left guide wheel and the limit adjustment member (3) of the right guide wheel in a direction towards the right guide wheel, and limit adjustment members (3) for the left guide wheel and the right guide wheel, respectively, to limit the steering ranges of the left guide wheel and the right guide wheel, respectively;

wherein,

the limiting adjusting component (3) directly abuts against the wheel seat (8) of the left guide wheel and the right guide wheel when limiting the left guide wheel and the right guide wheel, or

The limiting adjustment component (3) abuts against a stopping component (5) when limiting the left guide wheel and the right guide wheel, and the stopping component (5) is fixed to wheel seats (8) of the left guide wheel and the right guide wheel.

2. The automated guided vehicle according to claim 1, wherein the reverse motion generating mechanism (10) comprises a motor (11) and a set of positive and negative lead screws (2), the motor (11) drives a screw (21) of the set of positive and negative lead screws (2), and the limit adjusting member (3) is fixed to a nut (22) of the set of positive and negative lead screws (2).

3. The automated guided vehicle according to claim 2, wherein the motor (11) drives the screw (21) of the set of positive and negative screws (2) through a timing belt (12).

4. The automated guided vehicle according to claim 2, wherein the motor (11) is coupled to the threaded rod (21) of the set of positive and negative threaded rods (2) by means of a coupling.

5. The automated guided vehicle according to claim 1, wherein the reverse motion generating mechanism (10) comprises a motor (11) and a timing belt, the motor (11) drives the timing belt to rotate, and the limit adjustment member (3) is disposed on the timing belt for linear motion.

6. The automated guided vehicle according to claim 1, wherein the reverse motion generating mechanism (10) includes a motor (11) and two sets of rack and pinion mechanisms, a gear of one of the two sets of rack and pinion mechanisms is connected to an output shaft of the motor (11), and a gear of the other set of rack and pinion mechanisms is connected to an output shaft of the motor (11) via another gear, and the limit adjusting member (3) is fixed on a rack of the two sets of rack and pinion mechanisms.

7. Automated guided vehicle according to any of claims 1-6, characterized in that it further comprises a proximity sensor (6) for limiting the limit movement range of the limit adjustment member (3).

8. Automated guided vehicle according to any of claims 1-6, characterized in that the limit adjustment members (3) of the left and/or right guide wheels are two in number, two limit adjustment members (3) being configured in the form of forks.

9. The automated guided vehicle of any of claims 1-6, comprising two guide wheel steering range control mechanisms for a set of front guide wheels and a set of rear guide wheels, respectively; a set of front guide wheels comprising: a front left wheel (4FL) and a front right wheel (4FR) provided on the chassis (7); a set of rear guide wheels comprising: a left rear wheel (4RL) and a right rear wheel (4RR) which are arranged on the chassis (7).

10. Automated guided vehicle according to any of claims 1-6, characterized in that the automated guided vehicle comprises a drive train (9), which is a two-motor differential steering train.

11. Use of an automated guided vehicle (1) according to any of the preceding claims in warehouse logistics.