CN116295447B

CN116295447B - Path tracking method and automatic navigation vehicle

Info

Publication number: CN116295447B
Application number: CN202310580212.0A
Authority: CN
Inventors: 刘友; 李陆洋; 方牧; 鲁豫杰; 邓杰雄
Original assignee: Visionnav Robotics Shenzhen Co Ltd
Current assignee: Visionnav Robotics Shenzhen Co Ltd
Priority date: 2023-05-23
Filing date: 2023-05-23
Publication date: 2023-08-15
Anticipated expiration: 2043-05-23
Also published as: CN116295447A

Abstract

The embodiment of the application discloses a path tracking method and an automatic navigation vehicle, wherein the method comprises the following steps: determining a delay position corresponding to the current position of the AGV in the running process of the AGV; determining a target reference track point closest to the delay position from a plurality of reference track points included in the planned reference track; based on the membership function and the fuzzy rule, determining a forward looking distance gain corresponding to the current position according to track point information corresponding to the target reference track point; and determining a forward looking distance corresponding to the current position according to the forward looking distance gain, and determining a target steering angle corresponding to the AGV at the delay position according to the forward looking distance. By implementing the embodiment, the control precision of the AGV can be ensured, and the debugging efficiency of the AGV is improved.

Description

Path tracking method and automatic navigation vehicle

Technical Field

The present application relates to the field of vehicle control technologies, and in particular, to a path tracking method and an automatic navigation vehicle.

Background

Current path tracking technology can obtain better control effect through debugging parameter on AGVs (Automated Guided Vehicles, automatic guided vehicles) of same type and hardware, can reach better control accuracy, but the hardware of different types of AGVs has the difference, and upper and lower layer communication time delay and steering wheel response are inconsistent, consequently need to pass through the tester in proper order to carry out manual debugging parameter to different types of AGVs, increased cost and time.

Disclosure of Invention

The embodiment of the application discloses a path tracking method and an automatic navigation vehicle, which not only can ensure the control precision of an AGV, but also can improve the debugging efficiency of the AGV.

The embodiment of the application discloses a path tracking method, which comprises the following steps:

determining a delay position corresponding to the current position of an AGV in the running process of the AGV; the delay position is a position to which the actuator of the AGV receives an instruction at the current position and is shifted after a response delay time length;

determining a target reference track point closest to the delay position from a plurality of reference track points included in the planned reference track;

based on a membership function and a fuzzy rule, determining a forward looking distance gain corresponding to the current position according to track point information corresponding to the target reference track point;

and determining the forward looking distance corresponding to the current position according to the forward looking distance gain, and determining the target steering angle of the AGV corresponding to the delay position according to the forward looking distance.

In one embodiment, the track point information corresponding to the target reference track point includes a target reference speed and a target reference curvature, and the membership function includes a first membership function and a second membership function;

The determining the forward looking distance gain corresponding to the current position according to the track point information corresponding to the target reference track point based on the membership function and the fuzzy rule comprises the following steps:

determining a first membership degree corresponding to each first fuzzy element in the first fuzzy theory domain according to the first membership degree function; the first blurring element is used for representing a speed range;

determining a second membership degree corresponding to each second fuzzy element in the second fuzzy theory domain based on the second membership degree function; the second blurring element is used for representing a curvature range;

based on a fuzzy rule, fuzzy reasoning is carried out according to the plurality of first fuzzy elements, the first membership degree corresponding to each first fuzzy element, the plurality of second fuzzy elements and the second membership degree corresponding to each second fuzzy element, and a fuzzy result is determined;

and performing a sharpening operation on the blurring result to obtain a forward looking distance gain corresponding to the current position.

In one embodiment, before determining the forward viewing distance gain corresponding to the current position according to the track point information corresponding to the target reference track point based on the membership function and the fuzzy rule, the method further includes:

Determining the maximum reference speed in the reference speeds corresponding to the plurality of reference track points respectively;

determining a plurality of speed ranges according to the maximum reference speed;

generating a first fuzzy element corresponding to each speed range to obtain a first fuzzy theory domain;

determining the maximum reference curvature in the reference curvatures corresponding to the plurality of reference track points respectively;

determining a plurality of curvature ranges according to the maximum reference curvature;

and generating a second fuzzy element corresponding to each curvature range to obtain a second fuzzy domain.

In one embodiment, the fuzzy result includes third membership degrees corresponding to a plurality of third fuzzy elements included in the output argument, the third fuzzy elements are used for representing forward looking distance gains, the third membership degrees corresponding to target third fuzzy elements are used for representing the degree that the forward looking distance gain corresponding to the current position belongs to the target third fuzzy elements, and the target third fuzzy elements are any one of the third fuzzy elements;

the step of performing the sharpening operation on the blurring result to obtain a forward looking distance gain corresponding to the current position includes:

and determining the forward looking distance gain corresponding to the current position according to the forward looking distance gain represented by each third fuzzy element and the corresponding third membership degree.

In one embodiment, before the fuzzy rule-based fuzzy inference is performed according to the plurality of first fuzzy elements, the first membership degree corresponding to each of the first fuzzy elements, the plurality of second fuzzy elements, and the second membership degree corresponding to each of the second fuzzy elements, the method further includes:

acquiring the maximum forward looking distance and the minimum forward looking distance of the AGV;

determining the maximum reference speed and the minimum reference speed in the reference speeds respectively corresponding to the plurality of reference track points;

determining a maximum forward looking distance gain according to the maximum forward looking distance and the maximum reference speed;

determining a minimum forward looking distance gain according to the minimum forward looking distance and the minimum reference speed;

determining a plurality of forward looking distance gains according to the maximum forward looking distance gain and the minimum forward looking distance gain;

and generating a third fuzzy element corresponding to each forward viewing distance gain to obtain an output domain.

In one embodiment, the determining the delay position corresponding to the current position of the AGV includes:

acquiring the current position, the current speed and the current steering angle of the AGV;

Determining a motion arc of the AGV according to the current speed, the current steering angle and the response delay time length;

and determining a delay position according to the current position and the motion arc.

In one embodiment, the determining, according to the forward looking distance, the target steering angle of the AGV corresponding to the delay position includes:

determining a forward looking position according to the forward looking distance and the current position;

calculating a forward-looking included angle according to the forward-looking position, the delay position and the current position, wherein the forward-looking included angle is an included angle between a tangent line of a motion arc from the current position to the delay position at the current position and a straight line from the current position to the forward-looking position;

and determining a target steering angle corresponding to the AGV at the delay position according to the forward looking distance, the forward looking included angle and the wheelbase of the AGV.

In one embodiment, the AGV includes a steering wheel, two directional wheels, and an odometer device disposed at a center position of the two directional wheels, and an wheelbase of the AGV is a distance between the steering wheel and the center position of the two directional wheels.

In one embodiment, after the determining the forward looking distance corresponding to the current position according to the forward looking distance gain, and determining the target steering angle of the AGV corresponding to the delay position according to the forward looking distance, the method further includes:

acquiring a target reference speed corresponding to the target reference track point and taking the target reference speed as a target speed corresponding to the delay position;

and sending an instruction including the target steering angle and the target speed to the actuator at the current position to cause the AGV to operate at the target speed and the target steering angle at the delay position.

The embodiment of the application discloses an automatic navigation vehicle, which comprises:

the position determining module is used for determining a delay position corresponding to the current position of the AGV in the running process of the AGV; the delay position is a position to which the actuator of the AGV receives an instruction at the current position and is shifted after a response delay time length;

the track determining module is used for determining a target reference track point closest to the delay position from a plurality of reference track points included in the planned reference track;

The gain determining module is used for determining the forward looking distance gain corresponding to the current position according to the track point information corresponding to the target reference track point based on the membership function and the fuzzy rule;

and the steering determining module is used for determining the forward looking distance corresponding to the current position according to the forward looking distance gain and determining the target steering angle of the AGV corresponding to the delay position according to the forward looking distance.

the gain determining module is further configured to determine a first membership degree corresponding to each first fuzzy element in the first fuzzy theory domain at the target reference speed based on a first membership degree function; the first blurring element is used for representing a speed range; determining a second membership degree corresponding to each second fuzzy element in the second fuzzy theory domain based on the second membership degree function; the second blurring element is used for representing a curvature range; based on a fuzzy rule, fuzzy reasoning is carried out according to the plurality of first fuzzy elements, the first membership degree corresponding to each first fuzzy element, the plurality of second fuzzy elements and the second membership degree corresponding to each second fuzzy element, and a fuzzy result is determined; and performing a sharpening operation on the blurring result to obtain a forward looking distance gain corresponding to the current position.

In one embodiment, the automatic navigation vehicle further includes a domain determining module, configured to determine a maximum reference speed among the reference speeds corresponding to the plurality of reference track points, respectively; determining a plurality of speed ranges according to the maximum reference speed; generating a first fuzzy element corresponding to each speed range to obtain a first fuzzy theory domain; determining the maximum reference curvature in the reference curvatures corresponding to the plurality of reference track points respectively; determining a plurality of curvature ranges according to the maximum reference curvature; and generating a second fuzzy element corresponding to each curvature range to obtain a second fuzzy domain.

In one embodiment, the fuzzy result includes third membership degrees corresponding to a plurality of third fuzzy elements included in the output argument, the third fuzzy elements are used for representing forward looking distance gains, the third membership degrees corresponding to target third fuzzy elements are used for representing the degree that the forward looking distance gain corresponding to the current position belongs to the target third fuzzy elements, and the target third fuzzy elements are any one of the third fuzzy elements; the gain determining module is further configured to determine a forward looking distance gain corresponding to the current position according to the forward looking distance gains represented by the third fuzzy elements and the corresponding third membership degrees.

In one embodiment, the domain determination module is further configured to obtain a maximum forward looking distance and a minimum forward looking distance of the AGV; determining the maximum reference speed and the minimum reference speed in the reference speeds respectively corresponding to the plurality of reference track points; determining a maximum forward looking distance gain according to the maximum forward looking distance and the maximum reference speed; determining a minimum forward looking distance gain according to the minimum forward looking distance and the minimum reference speed; determining a plurality of forward looking distance gains according to the maximum forward looking distance gain and the minimum forward looking distance gain; and generating a third fuzzy element corresponding to each forward viewing distance gain to obtain an output domain.

In one embodiment, the position determining module is further configured to obtain a current position, a current speed, and a current steering angle of the AGV; determining a motion arc of the AGV according to the current speed, the current steering angle and the response delay time length; and determining a delay position according to the current position and the motion arc.

In one embodiment, the steering determination module is configured to determine a forward looking position based on the forward looking distance and the current position; calculating a forward-looking included angle according to the forward-looking position, the delay position and the current position, wherein the forward-looking included angle is an included angle between a tangent line of a motion arc from the current position to the delay position at the current position and a straight line from the current position to the forward-looking position; and determining a target steering angle corresponding to the AGV at the delay position according to the forward looking distance, the forward looking included angle and the wheelbase of the AGV.

In one embodiment, the automatic navigation vehicle further includes an instruction sending module, configured to obtain a target reference speed corresponding to the target reference track point, and use the target reference speed as the target speed corresponding to the delay position; and sending an instruction including the target steering angle and the target speed to the actuator at the current position to cause the AGV to operate at the target speed and the target steering angle at the delay position.

According to the path tracking method and the automatic navigation vehicle disclosed by the embodiment of the application, the AGV can determine the delay position corresponding to the current position of the AGV according to the response delay time of the AGV in the running process of the planned reference track, and determine the target reference track point closest to the delay position from a plurality of reference track points included in the planned reference track, and then based on membership functions and fuzzy rules, the AGV can determine the forward looking distance gain corresponding to the current position according to track point information corresponding to the target reference track point, and can determine the forward looking distance corresponding to the current position according to the forward looking distance gain, and determine the target steering angle of the AGV corresponding to the delay position according to the forward looking distance.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following description will briefly explain the drawings needed in the embodiments, and it is obvious that the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.

Fig. 1 is a schematic diagram of an application scenario of a path tracking method disclosed in an embodiment of the present application;

FIG. 2 is a schematic flow chart of a path tracking method according to an embodiment of the present application;

FIG. 3 is a flow chart of another path tracking method disclosed in an embodiment of the present application;

FIG. 4 is a flow chart of yet another path tracking method disclosed in an embodiment of the present application;

fig. 5 is a schematic diagram of an application scenario of another path tracking method disclosed in an embodiment of the present application;

FIG. 6 is a schematic diagram of an automated guided vehicle according to an embodiment of the present application;

fig. 7 is a block diagram of an automatic navigation vehicle according to an embodiment of the present application.

Detailed Description

The following description of the embodiments of the present application will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.

It should be noted that the terms "comprises" and "comprising," along with any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed or inherent to such process, method, article, or apparatus, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

It will be understood that the terms first, second, etc. as used herein may be used to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another element. For example, a first membership function may be referred to as a second membership function, and similarly, a second membership function may be referred to as a first membership function, without departing from the scope of the present application. The first membership function and the second membership function are both membership functions, but they are not the same membership function.

The following detailed description will be given with reference to the accompanying drawings.

As shown in fig. 1, fig. 1 is a schematic diagram of an application scenario of a path tracking method according to an embodiment of the present application, where the application scenario may include an AGV110, and the AGV110 may include, but is not limited to, an electromagnetic induction guided AGV, a laser guided AGV, and a vision guided AGV. Before the AGV110 starts to run, the AGV110 may determine a reference track and run according to the reference track, where the reference track may be planned by the AGV110 according to a start position and a target position, or the reference track may be planned by a control device connected to the AGV110 according to the start position and the target position and sent to the AGV110, which is not limited.

Since the response delay time of the actuator of the AGV110 is also taken into account when sending the order to the actuator of the AGV110, that is, the actuator of the AGV110 receives the order at the current position, the actuator of the AGV110 cannot immediately execute the order according to the order, but does not execute the order until after the response delay time, after which the AGV110 can move from the current position to the delay position, that is, the AGV110 can execute the order at the delay position.

In the running process of the AGV110, the AGV110 may determine a delay position corresponding to the current position of the AGV110, determine a target reference track point closest to the delay position from a plurality of reference track points included in the planned reference track, determine a forward looking distance gain corresponding to the current position according to track point information corresponding to the target reference track point based on a membership function and a fuzzy rule, and the AGV110 may determine a forward looking distance corresponding to the current position according to the forward looking distance gain and determine a target steering angle corresponding to the delay position according to the forward looking distance.

As shown in fig. 2, fig. 2 is a schematic flow chart of a path tracking method disclosed in the embodiment of the present application, where the path tracking method may be applied to the AGV in the above embodiment, and the path tracking method may include the following steps:

step 210, determining a delay position corresponding to the current position of the AGV in the running process of the AGV.

After the AGV acquires the planned reference track, the AGV can run according to the reference track, optionally, the AGV can determine the corresponding reference speed and the corresponding reference steering angle of each reference track point according to the reference track, and run at each reference track point according to the corresponding reference speed and the corresponding reference steering angle of each reference track point so as to reach the next reference track point, so that the AGV can sequentially reach a plurality of reference track points in the reference track.

In the running process of the AGV, the AGV can determine a delay position corresponding to the current position of the AGV, wherein the delay position is a position to which an actuator of the AGV receives an instruction at the current position and is displaced after a response delay time length. Optionally, the actuator of the AGV receives the command at the current position, which may include a speed and a steering angle such that the AGV operates at the speed and the steering angle in the command, but since the actuator of the AGV can only respond after a response delay period has elapsed after receiving the command, the AGV may be displaced from the current position to the delay position after the response delay period has elapsed, and the AGV may operate at the speed and the steering angle in the command at the delay position.

The response delay time of the AGV can be predetermined, optionally, the response delay of the AGV can be measured in advance by a worker or stored in the AGV when leaving a factory, and the method for measuring the response delay time of the AGV is not particularly described or limited.

Step 220, determining a target reference track point closest to the delay position from a plurality of reference track points included in the planned reference track.

Errors may occur when the AGV follows a reference trajectory, thereby causing the AGV to deviate from the reference trajectory, and thus the errors may be corrected. The AGV may determine a target reference trajectory point closest to the delay position from among a plurality of reference trajectories included in the planned reference trajectory.

Optionally, the planned reference track may include a plurality of reference track points, the AGV may calculate a distance between a position of each reference track point and the delay position, compare the distance corresponding to each reference track point, and use the reference track point with the smallest corresponding distance as the target reference track point, that is, the target reference track point is the reference track point with the closest distance to the delay position among the plurality of reference track points.

As an alternative implementation manner, the reference track point may also correspond to a reference time, where the reference time is when the AGV arrives at the reference track point according to the planned reference track. The AGV can add the response delay time to the current time to obtain the delay time, and then determine the target reference track point corresponding to the target reference time closest to the delay time. Optionally, the AGV may calculate a time difference between the reference time and the delay time corresponding to each reference track point, compare the time differences corresponding to each reference track point, and use the reference track point with the smallest corresponding time difference as the target reference track point. By implementing the embodiment, the method diversity of the AGV for determining the target reference track point is improved so as to adapt to various application scenes.

Step 230, determining the forward looking distance gain corresponding to the current position according to the track point information corresponding to the target reference track point based on the membership function and the fuzzy rule.

The AGV can determine the forward looking distance gain corresponding to the current position according to the track point information corresponding to the target reference track point based on the membership function and the fuzzy rule. The track point information corresponding to the target reference track point may include, but is not limited to, a reference speed and a reference curvature of the target reference track point. The AGV can fuzzify track point information corresponding to a target reference track point through a membership function to obtain a fuzzy input value corresponding to the fuzzy rule, and based on the fuzzy rule, fuzzy reasoning is carried out on the fuzzy input value to obtain a fuzzy output value, the fuzzy output value is a fuzzy result, and the fuzzy result is subjected to a definition operation to obtain a forward vision distance gain corresponding to the current position.

The AGV may calculate a reference curvature of each reference track point in the reference track, and optionally, taking the target reference track point as an example, the AGV may determine the reference curvature of the target reference track point according to the position information of the target reference track point, the position information of a first reference track point and the position information of a second reference track point, where the first reference track point may be a track point next to the target reference track point, and the second reference track point may be a track point next to the first reference track point. As shown in the formula (1), the formula (1) is a formula for calculating a reference curvature,

formula (1);

wherein ,for the reference curvature of the target reference trajectory point, (-)>) For the position information of the target reference track point, (-)>) For the position information of the first reference track point, (-)>) Is the position information of the second reference track point.

Optionally, the membership functions may be preset, the membership functions may include a plurality of membership functions, the number of membership functions may be the same as the number of types of track point information corresponding to the target reference track point, for example, in the case that the track point information corresponding to the target reference track point includes the reference speed and the reference curvature of the target reference track point, the membership functions may include 2 membership functions, each membership function corresponds to one type of information of track point information corresponding to the target reference track point, for example, the membership functions may include a first membership function and a second membership function, the first membership function may correspond to the reference speed, and the second membership function may correspond to the reference curvature. Taking the reference speed as an example, the fuzzy determination of the speed by the AGV can comprise fast, medium and slow, the reference speed can be 1 m/s, the AGV can determine that the reference speed belongs to the fast first membership degree as 0, the first membership degree in the reference speed belongs to 0.2, and the reference speed belongs to the slow first membership degree as 0.9 based on the first membership degree function.

Optionally, the fuzzy rule may be preset, where the fuzzy rule may include a set of multiple conditional sentences, and the AGV may obtain a fuzzy output value corresponding to the fuzzy input value according to the fuzzy rule, for example, if the fuzzy input value represents the event a, the fuzzy output value represents the event X; if the fuzzy input value characterizes event B, the fuzzy output value characterizes event Y. Taking the reference speed as an example, if the fuzzy input value represents that the reference speed is fast, the speed of the fuzzy output value represents that the AGV is controlled to be reduced by 2 meters per second, if the fuzzy input value represents that the reference speed is medium, the speed of the fuzzy output value represents that the AGV is controlled to be increased by 4 meters per second, and if the fuzzy input value represents that the reference speed is slow, the speed of the fuzzy output value represents that the AGV is controlled to be increased by 8 meters per second.

Step 240, determining a forward looking distance corresponding to the current position according to the forward looking distance gain, and determining a target steering angle corresponding to the delay position of the AGV according to the forward looking distance.

The AGV can determine the forward looking distance corresponding to the current position according to the forward looking distance gain, and determine the target steering angle corresponding to the delay position of the AGV according to the forward looking distance. Alternatively, the AGV may determine the forward looking distance corresponding to the current position according to the forward looking distance gain and the current speed of the AGV, specifically, reference formula (2), where formula (2) is a formula for calculating the forward looking distance,

Formula (2);

wherein ,for the forward looking distance corresponding to the current position, +.>For forward viewing distance gain, < >>Is the current speed of the AGV. Optionally, the AGV may determine, based on a related path tracking algorithm, a target steering angle corresponding to the delay position of the AGV according to the forward looking distance.

In the embodiment of the application, the AGV can determine the delay position corresponding to the current position of the AGV according to the response delay time length of the AGV in the running process of the planned reference track, and determine the target reference track point closest to the delay position from a plurality of reference track points included in the planned reference track, then based on a membership function and a fuzzy rule, the AGV can determine the forward looking distance gain corresponding to the current position according to track point information corresponding to the target reference track point, and can determine the forward looking distance corresponding to the current position according to the forward looking distance gain, and determine the target steering angle of the AGV corresponding to the delay position according to the forward looking distance.

As shown in fig. 3, fig. 3 is a flowchart of another path tracking method disclosed in the embodiment of the present application, and the path tracking method may be applied to the AGV in the above embodiment, and the path tracking method may include the following steps:

step 302, determining a delay position corresponding to the current position of the AGV in the running process of the AGV.

Step 304, determining a target reference track point closest to the delay position from a plurality of reference track points included in the planned reference track.

The method of steps 302 to 304 is the same as the method of steps 210 to 220 in the above embodiment, and will not be repeated here.

Step 306, determining the maximum reference speed among the reference speeds corresponding to the plurality of reference track points respectively.

The AGV may compare the reference speeds corresponding to the respective reference track points and determine a maximum reference speed of the reference speeds corresponding to the respective reference track points. Optionally, the AGV may further determine a minimum reference speed among the reference speeds corresponding to the plurality of reference track points, and store the maximum reference speed and the minimum reference speed, where the AGV may directly obtain the maximum reference speed or the minimum reference speed when the AGV needs to use the maximum reference speed or the minimum reference speed, without comparing each time, so as to reduce the workload of the AGV.

Step 308, determining a plurality of speed ranges according to the maximum reference speed.

Since there is a direction of speed, the AGV may determine a maximum speed range from a negative maximum reference speed to a positive maximum reference speed based on the maximum speed range, the AGV may determine a plurality of speed ranges based on the maximum speed range, which may correspond to a basic argument in the fuzzy control, which may refer to an actual range of variation of a certain variable, which may be a reference speed. Optionally, the AGV may equally divide the maximum speed range into a plurality of speed ranges, with the divided speed ranges not overlapping, and for any two speed ranges, the lower speed limit of one speed range is not less than the upper speed limit of the other speed range. Alternatively, the AGV may divide the maximum speed range into multiple speed ranges without limitation, and the speed ranges may overlap.

In one example, the maximum reference speed may be 21 meters per second, the maximum speed range may be-21 meters per second to 21 meters per second, the maximum speed range may be 7 meters per second, the first speed range, the second speed range, the third speed range, the fourth speed range, the fifth speed range, the sixth speed range, and the seventh speed range may be-21 meters per second to-15 meters per second, -15 meters per second to-9 meters per second, -9 meters per second to-3 meters per second, -3 meters per second to 3 meters per second, 3 meters per second to 9 meters per second, 9 meters per second to 15 meters per second, and 15 meters per second to 21 meters per second, 7 speed ranges may also be-21 meters per second to-14 meters per second, -21 meters per second to-7 meters per second, -14 meters per second to 0 meters per second, -7 meters per second, 0 meters per second to 14 meters per second, -7 meters per second to 21 meters per second, and 21 meters per second to 21 meter per second.

And step 310, generating first fuzzy elements corresponding to each speed range to obtain a first fuzzy discourse domain.

The AGV can generate first fuzzy elements corresponding to each speed range to obtain a first fuzzy universe. Alternatively, the first fuzzy elements corresponding to the respective speed ranges may include negative large, negative medium, negative small, zero, positive small, medium and positive large, other forms of first fuzzy elements may be used, for example, in digital form, the first fuzzy elements corresponding to the respective speed ranges may include-3, -2, -1, 0, 1, 2, 3, for example, in letter form, the first fuzzy elements corresponding to the respective speed ranges may include NB, NM, NS, O, PS, PM and PB, which are not limited thereto, the speed range corresponding to each first fuzzy element is a fuzzy set of each first fuzzy element, and the first membership function corresponding to the respective first fuzzy element is preset.

In one example, the AGVs may obtain 7 speed ranges of-21 meters per second to-14 meters per second, -21 meters per second to-7 meters per second, -14 meters per second to 0 meters per second, -7 meters per second to 7 meters per second, 0 meters per second to 14 meters per second, 7 meters per second to 21 meters per second, and 14 meters per second to 21 meters per second, respectively, -21 meters per second to-14 meters per second, -21 meters per second to-7 meters per second, a negative small corresponding speed range may be-14 meters per second to 0 meters per second, a zero corresponding speed range may be-7 meters per second to 7 meters per second, a positive small corresponding speed range may be 0 meters per second to 14 meters per second, a positive medium corresponding speed range may be 7 meters per second to 21 meters per second, a positive large corresponding speed range may be 14 meters per second to 21 meters per second.

In step 312, a maximum reference curvature of the reference curvatures corresponding to the plurality of reference trajectory points, respectively, is determined.

The AGV may first calculate the reference curvatures corresponding to the respective reference trajectory points, compare the reference curvatures corresponding to the respective reference trajectory points, and determine the maximum reference curvature of the reference curvatures corresponding to the respective reference trajectory points. Optionally, the AGV may calculate the reference curvature of the target reference track point based on the reference position of the target reference track point, the reference position of the next reference track point of the target reference track point, and the reference position of the next reference track point of the target reference track point.

In step 314, a plurality of curvature ranges are determined based on the maximum reference curvature.

The AGV may determine a maximum curvature range from 0 to the maximum reference curvature based on the maximum reference curvature, and the AGV may determine a plurality of curvature ranges based on the maximum curvature range, which may correspond to another basic domain in fuzzy control. Optionally, the AGV may equally divide the maximum curvature range into a plurality of curvature ranges, with the bisected curvature ranges not overlapping, and for any two curvature ranges, the lower curvature limit of one curvature range is not less than the upper curvature limit of the other curvature range. Alternatively, the AGV may divide the maximum curvature range into a plurality of curvature ranges without limitation, and the curvature ranges may overlap. The method of determining the plurality of curvature ranges may refer to determining the range of the plurality of speed ranges, and is not illustrated herein.

And step 316, generating second fuzzy elements corresponding to each curvature range to obtain a second fuzzy discourse domain.

The AGV can generate second fuzzy elements corresponding to each curvature range to obtain a second fuzzy universe. Optionally, the second fuzzy elements corresponding to each curvature range may include negative large, negative medium, negative small, zero, positive small, positive and positive large, other forms of second fuzzy elements may be used, such as digital forms, the second fuzzy elements corresponding to each curvature range may include-3, -2, -1, 0, 1, 2, 3, such as letter forms, the second fuzzy elements corresponding to each curvature range may include NB, NM, NS, O, PS, PM and PB, without limitation, the curvature range corresponding to each second fuzzy element is a fuzzy set of each second fuzzy element, and the second membership function corresponding to each second fuzzy element is preset.

In step 318, a first membership of the target reference speed to each first fuzzy element in the first fuzzy theory domain is determined based on the first membership function.

The first fuzzy theory domain may include a plurality of first fuzzy elements, the first fuzzy elements are used for representing a speed range, the first membership corresponding to the target first fuzzy elements is used for representing the degree that the target reference speed belongs to the target first fuzzy elements, and the target first fuzzy elements are any one of the plurality of first fuzzy elements included in the first fuzzy theory domain.

In one example, the plurality of first fuzzy elements includes negative large, negative medium, negative small, zero, positive small, median, and positive large, the first membership function is as shown in equation (3),

formula (3);

wherein ,for the first membership->For reference speed +.>For the minimum speed of the speed range corresponding to the first blurring element,/or->For the first blurred element pairMaximum speed of the corresponding speed range, +.>For the intermediate speed of the speed range corresponding to the first blurring element, the speed range corresponding to the positive small may be 0 meter per second to 14 meter per second, the speed range corresponding to the positive medium may be 7 meter per second to 21 meter per second, the speed range corresponding to the positive large may be 14 meter per second to 21 meter per second, the target reference speed is 10.5 meter per second, the first membership of the target reference speed corresponding to the positive small may be 0.25, the first membership of the target reference speed corresponding to the positive medium may be 0.25, and the first membership of the target reference speed corresponding to the positive large may be 0, so that examples of negative large, negative medium, negative small and zero are omitted.

A specific calculation process of the first membership degree is described by taking the first membership degree corresponding to the target reference speed and the positive small as an example, when the first membership degree corresponding to the target reference speed and the positive small is determined, the speed range corresponding to the positive small is 0 m/s to 14 m/s, then 0 meters per second>14 meters per second>The target reference speed is 10.5 meters per second, 7 meters per second, i.e. +.>At 10.5 meters per second, available with substitution formula (3), use +.>Corresponding formula->3.5 @, @>14, the first membership of the target reference speed corresponding to positive small is 0.25.

Optionally, the AGV may obtain a first vector based on the first membership function, where the first vector includes a plurality of first membership degrees, for example, the target reference speed is 10.5 meters per second, the first vector may be (0,0,0,0,0.25,0.25,0), a first value 0 in the first vector indicates that the target reference speed is of a negative high degree, a second value 0 in the first vector indicates that the target reference speed is of a negative low degree, a third value 0 in the first vector indicates that the target reference speed is of a negative low degree, a fourth value 0 in the first vector indicates that the target reference speed is of a zero degree, a fifth value 0.25 in the first vector indicates that the target reference speed is of a positive low degree, a sixth value 0.25 in the first vector indicates that the target reference speed is of a positive high degree, and a seventh value 0 in the first vector indicates that the target reference speed is of a positive high degree.

Step 320, determining a second membership degree of the target reference curvature corresponding to each second fuzzy element in the second fuzzy domain based on the second membership function.

The second fuzzy theory domain may include a plurality of second fuzzy elements, the second fuzzy elements are used for representing a curvature range, the second membership corresponding to the target second fuzzy elements is used for representing the degree that the target reference curvature belongs to the target second fuzzy elements, and the target second fuzzy elements are any one of the plurality of second fuzzy elements included in the second fuzzy theory domain. The method of step 320 may refer to the example of step 318, which is not described herein.

Step 322, based on the fuzzy rule, fuzzy reasoning is performed according to the plurality of first fuzzy elements, the first membership degree corresponding to each first fuzzy element, the plurality of second fuzzy elements and the second membership degree corresponding to each second fuzzy element, and a fuzzy result is determined.

The AGV can perform fuzzy reasoning based on the fuzzy rule according to the first fuzzy elements, the first membership degree corresponding to each first fuzzy element, the second fuzzy elements and the second membership degree corresponding to each second fuzzy element to determine a fuzzy result.

Optionally, the fuzzy result may include third membership degrees corresponding to a plurality of third fuzzy elements included in the output argument, the third fuzzy elements are used for representing forward looking distance gains, the third membership degrees corresponding to the target third fuzzy elements are used for representing the degree that the forward looking distance gain corresponding to the current position belongs to the target third fuzzy elements, and the target third fuzzy elements are any one of the plurality of third fuzzy elements. The output argument is predetermined, and the forms of the plurality of third fuzzy elements may refer to the forms of the first fuzzy element and the second fuzzy element, which are not described herein.

Optionally, the AGV may determine, based on the fuzzy rule, a target third fuzzy element corresponding to the target first fuzzy element and the target second fuzzy element from a plurality of third fuzzy elements included in the output argument, and may determine a third membership corresponding to the target third fuzzy element according to the first membership corresponding to the target first fuzzy element and the second membership corresponding to the target second fuzzy element. Optionally, the AGV may use the larger membership degree or the smaller membership degree of the first membership degree corresponding to the first fuzzy element and the second membership degree corresponding to the second fuzzy element as the third membership degree corresponding to the third fuzzy element, or may determine the third membership degree corresponding to the third fuzzy element by using other calculation methods, which is not limited.

As an example, the plurality of first blurring elements includes negative large, negative medium, negative small, zero, positive small, median and positive large, the plurality of second blurring elements includes negative large, negative medium, negative small, zero, positive small, median and positive large, the plurality of third blurring elements includes negative large, negative medium, negative small, zero, positive small, median and positive large, the blurring rule may be as shown in table (1),

watch (1)

Wherein, the elements in the first column are D1, D1 is the first blurring element, the elements in the second column are D2, D2 is the second blurring element, the other elements are D3, D3 is the third blurring element, for example, when D1 is negative large and D2 is negative large, D3 corresponding to D1 and D2 is zero.

In one embodiment, before step 322, the AGV may obtain a maximum forward looking distance and a minimum forward looking distance of the AGV, determine a maximum reference speed and a minimum reference speed of the reference speeds corresponding to the plurality of reference track points, respectively, the AGV may determine a maximum forward looking distance gain according to the maximum forward looking distance and the maximum reference speed, determine a minimum forward looking distance gain according to the minimum forward looking distance and the minimum reference speed, and determine a plurality of forward looking distance gains according to the maximum forward looking distance gain and the minimum forward looking distance gain, and the AGV may generate a third fuzzy element corresponding to each forward looking distance gain to obtain an output argument.

The maximum forward looking distance and the minimum forward looking distance can be measured in advance, the maximum forward looking distance is the forward looking distance when the AGV walks the straight line section at the maximum speed without obvious twisting, and the minimum forward looking distance is the forward looking distance required by the AGV to walk the maximum curvature without deviating from the path. Optionally, the AGV may divide the maximum forward looking distance by the maximum reference speed to obtain the maximum forward looking distance gain, and may divide the minimum forward looking distance by the minimum reference speed to obtain the minimum forward looking distance gain. Optionally, the AGV may determine a plurality of forward looking distance gains that are equi-progressively increasing, including a minimum forward looking distance gain and a maximum forward looking distance gain.

Step 324, performing a sharpening operation on the fuzzy result to obtain a forward looking distance gain corresponding to the current position.

The AGV can perform a sharpening operation on the fuzzy result to obtain a forward looking distance gain corresponding to the current position. In one embodiment, the fuzzy result may include third membership degrees corresponding to the plurality of third fuzzy elements, and the AGV may determine a forward looking distance gain corresponding to the current position according to the forward looking distance gain represented by each third fuzzy element and the corresponding third membership degrees. Optionally, the AGV may perform a clarification operation on the fuzzy result by using a gravity center method, and may add the product of the forward looking distance gain represented by each first fuzzy element and the corresponding third membership degree to obtain a gain weighted result, and divide the gain weighted result by the sum of the third membership degrees corresponding to each first fuzzy element to obtain the forward looking distance gain of the current position.

And 326, determining the forward looking distance corresponding to the current position according to the forward looking distance gain, and determining the target steering angle of the AGV corresponding to the delay position according to the forward looking distance.

In the embodiment of the application, the AGV can also determine the maximum reference speed in the reference speeds corresponding to the reference track points respectively so as to obtain a first fuzzy theory, determine the maximum reference curvature in the reference curvatures corresponding to the reference track points respectively so as to obtain a second fuzzy theory, improve the accuracy of the first fuzzy theory and the second fuzzy theory, further improve the control precision of the AGV, further determine the first membership of the target reference speed corresponding to each first fuzzy element in the first fuzzy theory based on a first membership function, determine the second membership of the target reference curvature corresponding to each second fuzzy element in the second fuzzy theory based on a second membership function, and then determine fuzzy results according to the first membership of the first fuzzy elements, the second fuzzy elements and the second membership corresponding to each second fuzzy element based on a fuzzy rule, and perform fuzzy reasoning operation on the fuzzy results so as to obtain the current position corresponding first membership function, and the clear tracking gain algorithm is not required by the method for tracking the distance by aiming at the path, and the clear tracking gain algorithm is not required.

As shown in fig. 4, fig. 4 is a flowchart of yet another path tracking method disclosed in the embodiment of the present application, and the path tracking method may be applied to the AGV in the above embodiment, and the path tracking method may include the following steps:

step 402, during the running process of the AGV, the current position, the current speed and the current steering angle of the AGV are obtained.

In the operation process of the AGV, the AGV can acquire the current position and the current speed of the AGV through measurement data of the first measuring device, the first measuring device can comprise an odometer, the AGV can acquire the current steering angle of the AGV through measurement data of the second measuring device, and the second measuring device can comprise a gyroscope. Optionally, the AGV may include a gyroscope and an odometer, where the AGV may set the gyroscope and the odometer in the same position to ensure that the current position, the current speed, and the current steering angle acquired by the AGV correspond to the same position.

Step 404, determining the motion arc of the AGV according to the current speed, the current steering angle and the response delay time length.

It will be appreciated that while the AGV is operating at a constant steering angle, the AGV will perform a circular motion with a radius that depends on the magnitude of the steering angle. Therefore, the motion arc of the AGV can be determined according to the current speed, the current steering angle and the response delay time length in the running process of the AGV.

Step 406, determining the delay position according to the current position and the motion arc.

The AGV may determine the delay position based on the current position and the arc of motion.

In step 408, a target reference track point closest to the delay position is determined from a plurality of reference track points included in the planned reference track.

Step 410, determining the forward looking distance gain corresponding to the current position according to the track point information corresponding to the target reference track point based on the membership function and the fuzzy rule.

Step 412, determining the forward looking distance corresponding to the current position according to the forward looking distance gain.

The method of steps 408-412 may refer to the method of the above embodiment, and will not be described herein.

In step 414, the forward looking position is determined based on the forward looking distance and the current position.

The AGV may determine the forward looking position based on the forward looking distance and the current position. Optionally, the AGV may determine a forward-looking reference track point in the reference track, where the reference position of the reference track point is a forward-looking distance from the current position, and the AGV may use the reference position of the forward-looking reference track point as the forward-looking position.

Step 416, calculating the forward looking angle according to the forward looking position, the delay position and the current position.

The forward-looking included angle is an included angle between a tangent line of a motion arc from the current position to the delay position at the current position and a straight line from the current position to the forward-looking position. Optionally, the AGV may determine a tangent to the motion arc at the current position, determine a line from the current position to the forward-looking position, and calculate an angle between the tangent and the line to obtain the forward-looking angle.

And 418, determining a target steering angle corresponding to the delay position of the AGV according to the forward looking distance, the forward looking included angle and the wheelbase of the AGV.

The AGV can determine a target steering angle corresponding to the delay position of the AGV according to the forward looking distance, the forward looking included angle and the wheelbase of the AGV. Alternatively, the AGV may calculate the target steering angle for the AGV at the delay position based on a pure tracking algorithm, specifically, as shown in equation (4),

formula (4);

wherein ,for the target steering angle of the AGV corresponding to the delay position, < >>For the forward vision distance>For the wheelbase of AGV, +.>Is the included angle of the front view.

The wheelbase of the AGV may be a distance between a front wheel center position of the AGV and a rear wheel center position of the AGV. Optionally, the AGV may include a steering wheel, two directional wheels, and an odometer device, where the odometer device is disposed at a center position of the two directional wheels, and an wheelbase of the AGV is a distance between the steering wheel and the center position of the two directional wheels, and the odometer device may include an odometer and a gyroscope, and may determine a current position, a current speed, and a current steering angle of the center position of the two directional wheels through the odometer device. Optionally, the odometer device may be disposed at another position, and the AGV may obtain the current position, the current speed, and the current steering angle of the other position through the odometer device, and determine the current position, the current speed, and the current steering angle of the center positions of the two directional wheels according to the relative positions between the other position and the center positions of the two directional wheels.

Step 420, obtaining a target reference speed corresponding to the target reference track point, and taking the target reference speed as a target speed corresponding to the delay position.

At 422, an instruction including the target steering angle and the target speed is sent to the effector at the current position to cause the AGV to operate at the target speed and the target steering angle at the delay position.

In the embodiment of the application, the AGV can also acquire the current position, the current speed and the current steering angle of the AGV, determine the motion arc of the AGV according to the current speed, the current steering angle and the response delay time, determine the delay position according to the current position and the motion arc, improve the accuracy of the delay position, determine the forward-looking position according to the forward-looking distance and the current position, calculate the forward-looking angle according to the forward-looking position, the delay position and the current position, and determine the target steering angle of the AGV corresponding to the delay position according to the forward-looking distance, the forward-looking angle and the wheelbase of the AGV, improve the accuracy of the target steering angle, and further transmit an instruction comprising the target steering angle and the target speed to the actuator at the current position as the target speed corresponding to the delay position.

As shown in fig. 5, fig. 5 is a schematic diagram of an application scenario of another path tracking method disclosed in the embodiment of the present application, where the AGV510 may include a first directional wheel 511, a second directional wheel 512, and a steering wheel 513, an odometer and a gyroscope included in the AGV510 may be set at a midpoint 514 of the first directional wheel 511 and the second directional wheel 512, that is, the midpoint 514 may also be used as a current position 514 of the AGV, the AGV510 obtains the current position 514, the current speed, and the current steering angle of the AGV through the odometer and the gyroscope, the AGV510 may determine a motion arc 520 of the AGV according to the current speed, the current steering angle, and a response delay time, and then determine a delay position 521 according to the current position 514 and the motion arc 520, and determine a target reference track point 531 closest to the delay position 521 from a plurality of reference track points included in a planned reference track 530, the AGV510 may determine a front viewing distance gain corresponding to the current position 514, the AGV510 may also determine a front viewing distance corresponding to the current position 514, and a front viewing angle corresponding to the current position 514, and a front position 510 may also determine a straight line of the AGV from the current position 514 to the current position 550, and a straight line of the current position 532 may also determine a front angle corresponding to the current position 510, and a straight line of the current position of the AGV is determined from the current position 510 to the current position 550 and the current position is determined.

As shown in fig. 6, fig. 6 is a schematic diagram of an automatic navigation vehicle 600 according to an embodiment of the present application, the automatic navigation vehicle 600 includes a position determining module 610, a trajectory determining module 620, a gain determining module 630, and a steering determining module 640, wherein:

the position determining module 610 is configured to determine a delay position corresponding to a current position of the AGV during an operation of the AGV; the delay position is the position to which the actuator of the AGV receives the instruction at the current position and is shifted after the response delay time length;

a track determining module 620, configured to determine a target reference track point closest to the delay position from a plurality of reference track points included in the planned reference track;

the gain determining module 630 is configured to determine a forward looking distance gain corresponding to the current position according to the track point information corresponding to the target reference track point based on the membership function and the fuzzy rule;

the steering determining module 640 is configured to determine a forward looking distance corresponding to the current position according to the forward looking distance gain, and determine a target steering angle corresponding to the delay position of the AGV according to the forward looking distance.

The gain determining module 630 is further configured to determine, based on the first membership function, a first membership degree of the target reference speed corresponding to each first fuzzy element in the first fuzzy theory domain; the first blurring element is used for representing a speed range; determining a second membership degree corresponding to each second fuzzy element in the second fuzzy theory domain based on the second membership degree function; the second blurring element is used for representing a curvature range; based on the fuzzy rule, fuzzy reasoning is carried out according to a plurality of first fuzzy elements, first membership degrees corresponding to the first fuzzy elements, a plurality of second fuzzy elements and second membership degrees corresponding to the second fuzzy elements, and a fuzzy result is determined; and performing a sharpening operation on the fuzzy result to obtain a forward looking distance gain corresponding to the current position.

In one embodiment, the automatic navigation vehicle further comprises a domain determining module, configured to determine a maximum reference speed of the reference speeds corresponding to the plurality of reference track points, respectively; determining a plurality of speed ranges according to the maximum reference speed; generating first fuzzy elements corresponding to each speed range to obtain a first fuzzy theory domain; determining the maximum reference curvature in the reference curvatures corresponding to the plurality of reference track points respectively; determining a plurality of curvature ranges according to the maximum reference curvature; and generating second fuzzy elements corresponding to each curvature range to obtain a second fuzzy discourse domain.

In one embodiment, the fuzzy result includes third membership degrees corresponding to a plurality of third fuzzy elements included in the output argument, the third fuzzy elements are used for representing forward looking distance gains, the third membership degrees corresponding to the target third fuzzy elements are used for representing the degree that the forward looking distance gain corresponding to the current position belongs to the target third fuzzy elements, and the target third fuzzy elements are any one of the third fuzzy elements; the gain determining module 630 is further configured to determine a forward looking distance gain corresponding to the current position according to the forward looking distance gains represented by the third fuzzy elements and the corresponding third membership degrees.

In one embodiment, the domain determining module is further configured to obtain a maximum forward looking distance and a minimum forward looking distance of the AGV; determining the maximum reference speed and the minimum reference speed in the reference speeds respectively corresponding to the plurality of reference track points; determining a maximum forward looking distance gain according to the maximum forward looking distance and the maximum reference speed; determining a minimum forward looking distance gain according to the minimum forward looking distance and the minimum reference speed; determining a plurality of forward looking distance gains according to the maximum forward looking distance gain and the minimum forward looking distance gain; and generating a third fuzzy element corresponding to each forward viewing distance gain to obtain an output domain.

In one embodiment, the position determination module 610 is further configured to obtain a current position, a current speed, and a current steering angle of the AGV; determining a motion arc of the AGV according to the current speed, the current steering angle and the response delay time length; the delay position is determined based on the current position and the arc of motion.

In one embodiment, the steering determination module 640 is configured to determine a forward looking position based on the forward looking distance and the current position; calculating a forward-looking included angle according to the forward-looking position, the delay position and the current position, wherein the forward-looking included angle is an included angle between a tangent line of a motion arc from the current position to the delay position at the current position and a straight line from the current position to the forward-looking position; and determining a target steering angle corresponding to the delay position of the AGV according to the forward looking distance, the forward looking included angle and the wheelbase of the AGV.

In one embodiment, the automatic navigation vehicle further includes an instruction sending module, configured to obtain a target reference speed corresponding to the target reference track point, and serve as a target speed corresponding to the delay position; an instruction including the target steering angle and the target speed is sent to the actuator at the current position to cause the AGV to operate at the target speed and the target steering angle at the delay position.

As shown in fig. 7, in one embodiment, an automated guided vehicle is provided, which may include:

a memory 710 storing executable program code;

a processor 720 coupled to the memory 710;

processor 720 invokes the executable program code stored in memory 710 to implement the path tracking method as provided in the various embodiments described above.

The Memory 710 may include a random access Memory (Random Access Memory, RAM) or a Read-Only Memory (ROM). Memory 710 may be used to store instructions, programs, code sets, or instruction sets. The memory 710 may include a stored program area and a stored data area, wherein the stored program area may store instructions for implementing an operating system, instructions for implementing at least one function (e.g., a touch function, a sound playing function, an image playing function, etc.), instructions for implementing the various method embodiments described above, and the like. The stored data area may also store data created by the automated guided vehicle in use, etc.

Processor 720 may include one or more processing cores. The processor 720 connects various parts within the overall automated guided vehicle using various interfaces and lines to perform various functions of the automated guided vehicle and process data by executing or executing instructions, programs, code sets, or instruction sets stored in the memory 710 and invoking data stored in the memory 710. Alternatively, the processor 720 may be implemented in hardware in at least one of digital signal processing (Digital Signal Processing, DSP), field programmable gate array (Field-Programmable Gate Array, FPGA), programmable logic array (Programmable Logic Array, PLA). The processor 720 may integrate one or a combination of several of a central processing unit (Central Processing Unit, CPU), an image processor (Graphics Processing Unit, GPU), and a modem, etc. The CPU mainly processes an operating system, a user interface, an application program and the like; the GPU is used for being responsible for rendering and drawing of display content; the modem is used to handle wireless communications. It will be appreciated that the modem may not be integrated into the processor 720 and may be implemented solely by a single communication chip.

It will be appreciated that the automated guided vehicle may include more or fewer structural elements than those described in the above structural block diagrams, including, for example, a power module, physical buttons, wiFi (Wireless Fidelity ) module, speakers, bluetooth module, sensors, etc., and may not be limited herein.

The embodiments of the present application disclose a computer-readable storage medium storing a computer program, wherein the computer program causes a computer to execute the method described in the above embodiments.

Furthermore, embodiments of the present application further disclose a computer program product that, when run on a computer, enables the computer to perform all or part of the steps of any of the path tracking methods described in the above embodiments.

Those of ordinary skill in the art will appreciate that all or part of the steps of the various methods of the above embodiments may be implemented by a program that instructs associated hardware, the program may be stored in a computer readable storage medium including Read-Only Memory (ROM), random access Memory (Random Access Memory, RAM), programmable Read-Only Memory (Programmable Read-Only Memory, PROM), erasable programmable Read-Only Memory (Erasable Programmable Read Only Memory, EPROM), one-time programmable Read-Only Memory (OTPROM), electrically erasable programmable Read-Only Memory (EEPROM), compact disc Read-Only Memory (Compact Disc Read-Only Memory, CD-ROM) or other optical disk Memory, magnetic disk Memory, tape Memory, or any other medium that can be used for carrying or storing data that is readable by a computer.

The above describes a path tracking method and an automatic navigation vehicle disclosed in the embodiments of the present application in detail, and specific examples are applied to illustrate the principles and embodiments of the present application, where the above description of the embodiments is only for helping to understand the method and core ideas of the present application; meanwhile, as those skilled in the art will have variations in the specific embodiments and application scope in accordance with the ideas of the present application, the present description should not be construed as limiting the present application in view of the above.

Claims

1. A method of path tracking, the method comprising:

determining a delay position corresponding to the current position of an AGV in the running process of the AGV; the delay position is a position to which an actuator of the AGV receives an instruction at the current position and is displaced after response delay time, wherein the AGV comprises a steering wheel, two directional wheels and an odometer device, the odometer device is arranged at the central positions of the two directional wheels, the wheelbase of the AGV is the distance between the steering wheel and the central positions of the two directional wheels, and the odometer device is used for determining the current position, the current speed and the current steering angle of the central positions of the two directional wheels;

determining a forward looking distance corresponding to the current position according to the forward looking distance gain, and determining a target steering angle corresponding to the AGV at the delay position according to the forward looking distance;

the forward looking distance is calculated using the following formula:

；

wherein ,for the forward looking distance corresponding to the current position, < >>For the forward looking distance gain, +.>A current speed for the AGV;

the determining the target steering angle corresponding to the AGV at the delay position according to the forward looking distance comprises the following steps:

calculating a forward-looking included angle according to the forward-looking position, the delay position and the current position, wherein the forward-looking included angle is an included angle between a tangent line of a motion arc from the current position to the delay position at the current position and a straight line from the current position to the forward-looking position; wherein determining an arc of motion of the current position to the delay position comprises: determining a motion arc from the current position to the delay position according to the current speed, the steering angle of the current position and the response delay time length;

Determining a target steering angle corresponding to the AGV at the delay position according to the forward looking distance, the forward looking included angle and the wheelbase of the AGV;

the track point information corresponding to the target reference track point comprises a target reference speed and a target reference curvature, the membership function comprises a first membership function and a second membership function, and the forward vision distance gain corresponding to the current position is determined according to the track point information corresponding to the target reference track point based on the membership function and a fuzzy rule, and the method comprises the following steps:

determining a first membership degree corresponding to each first fuzzy element in the first fuzzy theory domain according to the first membership degree function; the first blurring element is used for representing a speed range; determining a second membership degree corresponding to each second fuzzy element in the second fuzzy theory domain based on the second membership degree function; the second blurring element is used for representing a curvature range;

based on a fuzzy rule, fuzzy reasoning is carried out according to a plurality of first fuzzy elements, first membership degrees corresponding to the first fuzzy elements, a plurality of second fuzzy elements and second membership degrees corresponding to the second fuzzy elements, and a fuzzy result is determined; the fuzzy result comprises third membership degrees respectively corresponding to a plurality of third fuzzy elements included in an output argument, the third fuzzy elements are used for representing forward looking distance gains, the third membership degrees corresponding to target third fuzzy elements are used for representing the degree that the forward looking distance gain corresponding to the current position belongs to the target third fuzzy elements, and the target third fuzzy elements are any one of the third fuzzy elements;

2. The method according to claim 1, wherein before determining the forward viewing distance gain corresponding to the current position according to the track point information corresponding to the target reference track point based on the membership function and the fuzzy rule, the method further comprises:

3. The method of claim 1, wherein prior to the fuzzy rule-based fuzzy inference based on the plurality of first fuzzy elements, the first membership degree corresponding to each of the first fuzzy elements, the plurality of second fuzzy elements, and the second membership degree corresponding to each of the second fuzzy elements, the method further comprises:

4. The method of claim 1 wherein said determining a delay position corresponding to a current position of the AGV comprises:

5. The method according to any one of claims 1-4, wherein after the determining the forward looking distance corresponding to the current position according to the forward looking distance gain, and determining the target steering angle of the AGV corresponding to the delay position according to the forward looking distance, the method further comprises:

6. An automatic navigation vehicle, characterized in that the automatic navigation vehicle comprises:

the position determining module is used for determining a delay position corresponding to the current position of the AGV in the running process of the AGV; the delay position is a position to which an actuator of the AGV receives an instruction at the current position and is displaced after response delay time, wherein the AGV comprises a steering wheel, two directional wheels and an odometer device, the odometer device is arranged at the central positions of the two directional wheels, the wheelbase of the AGV is the distance between the steering wheel and the central positions of the two directional wheels, and the odometer device is used for determining the current position, the current speed and the current steering angle of the central positions of the two directional wheels;

the track point information corresponding to the target reference track point comprises a target reference speed and a target reference curvature, the membership function comprises a first membership function and a second membership function, and the track point information corresponding to the target reference track point is based on the membership function and a fuzzy rule;

the gain determining module is further configured to determine, based on a first membership function, a first membership degree corresponding to each first fuzzy element in the first fuzzy theory domain at the target reference speed; the first blurring element is used for representing a speed range; determining a second membership degree corresponding to each second fuzzy element in the second fuzzy theory domain based on the second membership degree function; the second blurring element is used for representing a curvature range; based on a fuzzy rule, fuzzy reasoning is carried out according to a plurality of first fuzzy elements, first membership degrees corresponding to the first fuzzy elements, a plurality of second fuzzy elements and second membership degrees corresponding to the second fuzzy elements, and a fuzzy result is determined; the fuzzy result comprises third membership degrees respectively corresponding to a plurality of third fuzzy elements included in an output argument, the third fuzzy elements are used for representing forward looking distance gains, the third membership degrees corresponding to target third fuzzy elements are used for representing the degree that the forward looking distance gain corresponding to the current position belongs to the target third fuzzy elements, and the target third fuzzy elements are any one of the third fuzzy elements; and the front view distance gain corresponding to the current position is determined according to the front view distance gain represented by each third fuzzy element and the corresponding third membership degree;

The steering determining module is used for determining a forward looking distance corresponding to the current position according to the forward looking distance gain and determining a target steering angle corresponding to the AGV at the delay position according to the forward looking distance;

the steering determination module is further configured to calculate the forward looking distance using the following formula:

；

the steering determination module is further configured to: determining a forward looking position according to the forward looking distance and the current position; calculating a forward-looking included angle according to the forward-looking position, the delay position and the current position, wherein the forward-looking included angle is an included angle between a tangent line of a motion arc from the current position to the delay position at the current position and a straight line from the current position to the forward-looking position; wherein determining an arc of motion of the current position to the delay position comprises: determining a motion arc from the current position to the delay position according to the current speed, the steering angle of the current position and the response delay time length; and the target steering angle corresponding to the delay position of the AGV is determined according to the forward looking distance, the forward looking included angle and the wheelbase of the AGV.