PATH TRACKING METHOD AND MOBILE ROBOT USING THE SAME

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First Claim
1. A computerimplemented path tracking method for a mobile device, comprising executing on a processor of the mobile device steps of:
 obtaining a preset path and a current position of the mobile device;
determining a forwardlooking path point corresponding to the current position on the preset path;
obtaining a path curvature corresponding to the forwardlooking path point;
determining an adjustment velocity of the mobile device at the current position based on the path curvature corresponding to the forwardlooking path point; and
adjusting a current velocity of the mobile device at the current position according to the adjustment velocity.
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Abstract
The present disclosure provides a path tracking method as well as a mobile robot using the same. The method includes: obtaining a preset path and a current position of the mobile device; determining a forwardlooking path point corresponding to the current position on the preset path; obtaining a path curvature corresponding to the forwardlooking path point; and determining an adjustment velocity of the mobile device at the current position based on the path curvature corresponding to the forwardlooking path point. In this manner, the adjustment velocity of the mobile device can be determined based on the curvature of the path, so as to adjust the velocity of the mobile device and improve the stability of path tracking of the mobile device at different path curvatures.
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20 Claims
 1. A computerimplemented path tracking method for a mobile device, comprising executing on a processor of the mobile device steps of:
obtaining a preset path and a current position of the mobile device; determining a forwardlooking path point corresponding to the current position on the preset path; obtaining a path curvature corresponding to the forwardlooking path point; determining an adjustment velocity of the mobile device at the current position based on the path curvature corresponding to the forwardlooking path point; and adjusting a current velocity of the mobile device at the current position according to the adjustment velocity.  View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
 12. A mobile robot, comprising:
a localization equipment; a memory; a processor; and one or more computer programs stored in the memory and executable on the processor, wherein the one or more computer programs comprise; instructions for obtaining a preset path and a current position of the mobile device, wherein the current position is obtained through the localization equipment; instructions for determining a forwardlooking path point corresponding to the current position on the preset path; instructions for obtaining a path curvature corresponding to the forwardlooking path point; instructions for determining an adjustment velocity of the mobile device at the current position based on the path curvature corresponding to the forwardlooking path point; and instructions for adjusting a current velocity of the mobile device at the current position according to the adjustment velocity.  View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20)
1 Specification
This application claims priority to Chinese Patent Application No. 201811289515.2, filed Oct. 31, 2018, which is hereby incorporated by reference herein as if set forth in its entirety.
The present disclosure relates to computing technology, and particularly to a path tracking method as well as a mobile robot using the same.
At present, the existing path tracking methods for a mobile objective such as a robot, a car, and a movable object usually select an intersection point of a path and a forwardlooking distance as a forwardlooking point, and make the mobile objective to move on a rail of the path by controlling the mobile objective to continuously move toward the updated forwardlooking point. However, at the positions near to the path points with large curvature, the path tracking methods tend to ignore the path points that should originally have reached, and there is occasionally the case that the mobile objective leaves the track and cannot be recovered.
To describe the technical schemes in the embodiments of the present disclosure more clearly, the following briefly introduces the drawings required for describing the embodiments or the prior art. Apparently, the drawings in the following description merely show some examples of the present disclosure. For those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
In the following descriptions, for purposes of explanation instead of limitation, specific details such as particular system architecture and technique are set forth in order to provide a thorough understanding of embodiments of the present disclosure. However, it will be apparent to those skilled in the art that the present disclosure may be implemented in other embodiments that are less specific of these details. In other instances, detailed descriptions of wellknown systems, devices, circuits, and methods are omitted so as not to obscure the description of the present disclosure with unnecessary detail.
For the purpose of describing the technical solutions of the present disclosure, the following describes through specific embodiments.
S101: obtaining a preset path and a current position of the mobile device.
In this embodiment, the preset path is a path at which the mobile device is moved that is to be tracked by the path tracking method. For example, the preset path can be a specified path or a path obtained through path planning, which is not limited herein. It can obtain path information of the preset path, for example, the path information of the preset path in a specified coordinate system.
The current position of the mobile device is a position at which the mobile device is located. The position information of the current position of the mobile objective can be obtained by, for example, positioning the mobile device by a localization method using the abovementioned localization equipment to obtain a coordinate of the current position of the mobile device in the specified coordinate system. It is should be noted that, the current position of the mobile device may be on the preset path and may be not.
In one embodiment, the position of the mobile device can be obtained during the mobile device being moved by using a localization method based on a preset time interval, a preset moving distance interval, or the like, which is not limited herein.
S102: determining a forwardlooking path point corresponding to the current position on the preset path.
In this embodiment, during the mobile device being moved, one path point on the preset path that is ahead of the mobile device can be selected to take as the forwardlooking path point (e.g., point P in
S201: obtaining a forwardlooking distance corresponding to the current position.
In this embodiment, the forwardlooking distances of the mobile device at different positions of the mobile device can be the same or different, which not limited herein. The forwardlooking distance is for determining the forwardlooking path point corresponding to the current position of the mobile device.
In one embodiment, S201 may include:
obtaining a preset forwardlooking distance and taking the preset forwardlooking distance as the forwardlooking distance corresponding to the current position; or
obtaining an adjustment forwardlooking distance corresponding to a previous position of the mobile device and taking the adjustment forwardlooking distance corresponding to the previous position as the forwardlooking distance corresponding to the current position.
In this embodiment, as an example, the preset forwardlooking distance can be obtained to take as the forwardlooking distance corresponding to the current position, so as to determine the forwardlooking path point corresponding to the current position. In which, the preset forwardlooking distance can be a fixed distance, and in this case, the corresponding forwardlooking distances while the mobile device is at different positions are the same; or a correspondence table between the preset forwardlooking distance and different positions can be generated in advance so that the corresponding preset forwardlooking distance can be searched from the correspondence table based on the current position of the mobile device, and in this case, the corresponding forwardlooking distances while the mobile device is at different positions can be the same or not the same, which is determined by the correspondence table. There can still be other ways to set the preset forwardlooking distance, which is not limited herein.
As another example, the forwardlooking distance can be adjusted during the path tracking, and the forwardlooking distance of the mobile device at the previous position can be adjusted to obtain the adjustment forwardlooking distance corresponding to the previous position, and then the adjustment forwardlooking distance can be taken as the corresponding forwardlooking distance of the mobile device at the current position, so as to determine the forwardlooking path point corresponding to the current position of the mobile device.
For example, assuming that an initial forwardlooking distance is set, and position A1, position A2, and position A3 are the positions of the mobile device which are successively adjacent to each other in order. When the mobile device is at position A1, the forwardlooking path point corresponding to position A1 is determined through the initial forwardlooking distance, and the initial forwardlooking distance is adjusted to obtain the adjustment forwardlooking distance corresponding to position A1; when the mobile device is at position A2, the adjustment forwardlooking distance corresponding to position A1 is taken as the forwardlooking distance of position A2, the forwardlooking path point corresponding to position A2 is determined, and the forwardlooking distance of position A2 is adjusted to obtain the adjustment forwardlooking distance corresponding to position A2; when the mobile device is at position A3, the adjustment forwardlooking distance corresponding to position A2 is taken as the forwardlooking distance of position A3, the forwardlooking path point corresponding to position A3 is determined, and the forwardlooking distance of position A3 is adjusted to obtain the adjustment forwardlooking distance corresponding to position A3. And then, the forwardlooking distance corresponding to the position of the mobile device can be obtained through the abovementioned manner, which is not described herein.
In this embodiment, the forwardlooking distance is continuously adjusted during the path tracking, and the adjustment forwardlooking distance corresponding to the previous position is taken as the forwardlooking distance corresponding to the current position, which can adjust the forwardlooking distance according to different path conditions in time, so that the forwardlooking distance can be more suitable for the current path condition, thereby making the forwardlooking path point determined through the forwardlooking distance to be more appropriate so as to improve the stability of path tracking.
S202: selecting a first path point on the preset path as the forwardlooking path point, where a distance between the first path point and the current position is the forwardlooking distance corresponding to the current position.
In this embodiment, a path point on the preset path that has a distance with respect to the current position of the mobile device equal to the forwardlooking distance corresponding to the current position can be selected as the forwardlooking path point. If there are a plurality of first path points on the preset path, one path point among the plurality of first path points that has a relative position of the backmost position can be selected as the forwardlooking path point. In which, the relative position of the backmost position means the case that the plurality of first path points are sorted according to a direction from a starting point of the preset path to an end point of the preset path, and the first path point that is arranged at the last position is determined as the forwardlooking path point corresponding to the current position.
S103: obtaining a path curvature corresponding to the forwardlooking path point.
In this embodiment, the path curvature of one path point is the curvature of a curve of the preset path at the path point, which is used to represent the degree of bending of the preset path at the path point. The path curvature corresponding to the forwardlooking path point can be the path curvature of the forwardlooking path point, the path curvature of one or more path points within a section of the preset path where the forwardlooking path point is located, or a result of a data calculation on the path curvature of one or more path points within a section of the preset path where the forwardlooking path point is located, which is not limited herein. In which, the data calculation can be a calculation such as addition, difference, multiplication, and weighted summation, which is not limited herein. The path curvature corresponding to the forwardlooking path point can be calculated based on the path information of the preset path.
S104: determining an adjustment velocity of the mobile device at the current position based on the path curvature corresponding to the forwardlooking path point, and adjusting a current velocity of the mobile device at the current position according to the adjustment velocity.
In this embodiment, the adjustment velocity is for indicating the velocity of the mobile device to be adjusted so that the mobile device is moved at the adjustment velocity. The path curvature corresponding to the forwardlooking path point can represent the degree of bending of the path ahead of the mobile device. In this embodiment, the adjustment velocity corresponding to each position of the mobile device is determined at the position, and the motion state of the mobile device can be adjusted in time according to the path condition, thereby improving the stability of path tracking of the mobile device. Through the determined adjustment velocity, the velocity of the mobile device can be adjusted to be lower in the case that the path curvature is large, thereby avoiding the mobile device from leaving the track can be avoided so as to improve the stability.
In this embodiment, the forwardlooking path point corresponding to the current position of the mobile device that is on the preset path is determined, and the adjustment velocity of the mobile device at the current position is determined based on the path curvature corresponding to the forwardlooking path point, which can determine the adjustment velocity of the mobile device based on the curvature of the path, so as to adjust the velocity of the mobile device, thereby improving the stability of path tracking of the mobile device at different path curvatures.
S301: selecting at least one path point on a section of the preset path at which the forwardlooking path point is located.
In this embodiment, one or more path points in the section of the preset path where the forwardlooking path point is located can be selected. The division of the section on the preset path can be determined according to actual needs, which is not limited herein.
S401: searching for a second path point corresponding to the current position, where the second path point is a vertical point on the preset path that corresponds to the current position.
In this embodiment, the vertical point on the preset path corresponding to the current position can be searched to take as the second path point corresponding to the current position. In the case that the current position of the mobile device is on the preset path, the current position of the mobile device can be taken as the second path point; in the case that the current position of the mobile device is not on the preset path, the vertical point corresponding to the current position can be searched on the preset path to take as the second path point. In which, the direction of a connection between the vertical point corresponding to the current position and the current position can be perpendicular to the tangential direction of the preset path at the vertical point.
As shown in
S402: selecting at least one path point on a section of the preset path between the second path point and the forwardlooking path point from the preset path.
In this embodiment, it can take the second path point and the forwardlooking path point as two end points of the section of the preset path, take the section on the preset path as the section where the forwardlooking path point is located, and select one or more path points from the section. For example, it can select one path point at every preset distance interval, select a preset number of path points from the section at uniform intervals, or select the path point according to other selection manners, which is not limited herein. As shown in
In this embodiment, the path point is selected from the section of the preset path between the vertical point corresponding to the current position on the preset path and the forwardlooking path point, so that the selected path point can more accurately reflect the path condition of the section of the preset path that is ahead of the mobile device, thereby making the determined adjustment velocity more accurate, so that the motion state of the mobile device can be adjusted more accurately and timely, thereby improving the stability of path tracking.
S302: calculating the adjustment velocity of the mobile device at the current position based on the path curvature corresponding to each path point.
In this embodiment, the path curvature corresponding to one path point can be the path curvature of the path point, or a result of a data calculation of the path curvature of the path point and the path curvature of other path points, which is not limited herein. For example, the data calculation can be a calculation such as addition, difference, multiplication, and weighted summation, which is not limited herein.
In this embodiment, the adjustment velocity is calculated based on the path curvatures corresponding to the plurality of path points of the section where the forwardlooking path point is located, which can make the calculated adjustment velocity more accurate, thereby improving the stability of path tracking.
S501: calculating the path curvature corresponding to each path point and a first distance corresponding to each path point, where the first distance corresponding to the path point is a distance between the path point and a previous path point.
In this embodiment, each path point corresponds to one first distance. Taking one path point as an example, the distance between the path point and its previous path point is the first distance corresponding to the path point. For example, each path point can be arranged according to a preset order, and the previous path point of the path point can be one path point that is adjacent to the path point and is arranged to be ahead of the path point. In which, the preset order can be an order from one end point to another end point of the section where the forwardlooking path point is located, or can have another arrangement order, which is not limited herein.
In one embodiment, step S501 may include:
calculating a difference between the path curvature of each path point and the path curvature of the previous path point to take as the path curvature corresponding to the path point.
In this embodiment, each path point corresponds to one path curvature.
Taking one path point as an example, the difference between the path curvature of the path point and the path curvature of its adjacent previous path point is taken as the path curvature corresponding to the path point.
In this embodiment, the difference between the path curvature of one path point and that of its previous path point is taken as the path curvature corresponding to the path point, which can make the path curvature corresponding to each path point accurately reflect the variation of the path curvature at each path point. By reflecting the path condition of the path ahead of the mobile device through the variation of the path curvature, the adjustment velocity of the mobile device can determined based on the variation of the path curvature, thereby improving the stability of path tracking.
S502: calculating a product of an absolute value of the path curvature corresponding to each path point and the first distance corresponding to the path point, and summing the products of all the path points to obtain a sum of the products.
In this embodiment, for one path point, the absolute value of the path curvature corresponding to the path point can be first calculated. For example, if the path curvature corresponding to one path point is the difference between the path curvature of the path point and the path curvature of its adjacent previous path point, the absolute value of the difference can be calculated. Then, the product of the absolute value and the first distance corresponding to the path point can be calculated. The product corresponding to each path point is respectively calculated, and the products corresponding to all the path points are added to obtain the sum. In which, the summing the products of all the path points can be directly summing the products corresponding to all the path points, or weighted summing the products corresponding to all the path points, which is not limited herein.
S503: determining an adjustment coefficient based on the sum of the products.
In this embodiment, the adjustment coefficient can be determined based on the sum of the products. The adjustment coefficient is for calculating the adjustment velocity of the mobile device.
S601: calculating a first ratio of the sum of the products to the forwardlooking distance, where the forwardlooking distance is a distance between the current position of the mobile device and the forwardlooking path point.
In this embodiment, it can obtain a coordinate of the current position and a coordinate of the forwardlooking path point, and calculate the forwardlooking distance based on the two coordinates; or in step S102, if the forwardlooking path point corresponding to the current position is determined through the forwardlooking distance corresponding to the current position, the forwardlooking distance can be directly obtained in step S601, so as to obtain the first ratio by dividing the sum of the products by the forwardlooking distance.
S602: determining the adjustment coefficient based on the first ratio.
In this embodiment, the forwardlooking distance is added to the consideration factor for determining the adjustment coefficient, which can have different adjustment to the motion state of the mobile device at different forwardlooking distances. By comprehensive consideration of two factors of the path curvature and the forwardlooking distance, the determined adjustment coefficient can be more appropriate, so that the determined adjustment velocity can be more suitable for the condition of the path in front of the mobile device, and the stability of path tracking can be improved.
In one embodiment, S602 can include:
calculating the adjustment coefficient based on a penalty function formula and the first ratio, where the penalty function formula is:
where, P is the adjustment coefficient, and X is the first ratio.
In this embodiment, by using the penalty function, the adjustment coefficient will be correspondingly decreased as the first ratio increases, and the smaller adjustment coefficient can be obtained while the path curvature is large, thereby slowing the velocity of the mobile device and improving the stability and robustness of the path tracking of the mobile device.
S504: calculating the adjustment velocity of the mobile device at the current position based on the adjustment coefficient and a current velocity of the mobile device.
In this embodiment, the velocity of the mobile device at the current position can be obtained to take as the current velocity, and the adjustment velocity of the mobile device at the current position is calculated based on the adjustment coefficient and the current velocity.
In this embodiment, the adjustment coefficient is determined based on three path condition related factors of the path curvature, the distance between the path points, and the forwardlooking distance, and the adjustment velocity is calculated based on the adjustment coefficient and the current velocity, so that the calculated adjustment velocity can be more suitable for the path condition, thereby increasing the stability of path tracking.
In one embodiment, the current velocity includes a current line velocity, and the adjustment velocity includes an adjustment line velocity and an adjustment angular velocity.
S701: calculating a product of the current linear velocity of the mobile device and the adjustment coefficient to obtain the adjustment linear velocity.
In this embodiment, the current line velocity is the line velocity of the mobile device at the current position. The current line velocity can be multiplied by the adjustment coefficient to obtain the adjustment line velocity. The adjustment line velocity is for indicating the mobile device to adjust the line velocity to the adjustment line velocity.
S702: calculating a product of the forwardlooking distance and the adjustment coefficient to obtain the adjustment forwardlooking distance, where the forwardlooking distance is a distance between the current position of the mobile device and the forwardlooking path point.
In this embodiment, the forwardlooking distance of the mobile device at the current position can be multiplied by the adjustment coefficient to obtain the adjustment forwardlooking distance. The adjustment forwardlooking distance is for determining the forwardlooking path point corresponding to the next position of the mobile device.
In this embodiment, the forwarddistance distance is adjusted by using the adjustment coefficient, and the forwardlooking distance is adjusted according to the path condition in time during the path tracking, so that the selection of the forwardlooking distance and the forwardlooking path point can be more suitable for the path condition in front, thereby improving the stability of path tracking. For example, the forwardlooking distance can be shortened when the path curvature is large, thereby improving the stability to track the mobile device at the path with large curvature.
S703: calculating the adjustment angular velocity based on the adjustment linear velocity, the adjustment forwardlooking distance, and a deviation angle, where the deviation angle is an included angle between a vector direction from the current position of the mobile device to the forwardlooking path point and a direction of the current linear velocity of the mobile device.
In this embodiment, it can take the current position of the mobile device as a starting point and take the forwardlooking path point as an end point to obtain a vector, where there is an included angle between the vector and the current line velocity of the mobile device, and the included angle is the deviation angle of the mobile device at the current position. The adjustment angular velocity can be calculated based on the adjustment linear velocity, the adjustment forwardlooking distance, and the deviation angle. The adjustment angular Velocity is for indicating the mobile device to adjust the angular velocity.
In this embodiment, the adjustment linear velocity, the adjustment forwardlooking distance, and the adjustment angular velocity are calculated through the adjustment coefficient, which adjusts the motion state of the mobile device through the abovementioned three during the path tracking, and the stability of path tracking can be improved through multiple aspects.
In one embodiment, S703 may include:
calculating a second ratio of the adjustment linear velocity to the adjustment forwardlooking distance; and
calculating a product of the sine of the deviation angle and the second ratio to obtain the adjustment angular velocity.
In this embodiment, it can divide the adjustment linear velocity by the adjustment forwardlooking distance to obtain the second ratio, then calculate the sine of the deviation angle, and then multiply the sine of the deviation angle by the second ratio to obtain the adjustment angular velocity.
A mobile robot is taken as an example as follows. As shown in
where,
Under the guidance of the abovementioned controller, the robot will be moved at the line velocity of V and the angular velocity of ω to ensure that the robot can track the path within a certain range.
However, in the case that the curvature of the path is large, the length L is likely to skip a section of the path.
In this embodiment, the curvature of the path is taken into consideration, and a penalty function with the path curvature as a variable is added to the forwardlooking distance L and the velocity of the robot, so that the robot can be moved slowly at which the curvature is large, and can be more close to the path. In which, the penalty function is as shown in formula (5):
where, N_{L. }is the number of all the path points in the section formed by point D and the forwardlooking path point P on the path; Δκ_{i}=κ_{i}−κ_{i−l }is the change between the path curvature of the ith path point and the path curvature of the ith path point,
is the path curvature of the ith path point, y_{i }is the curve equation of the path; Δs_{i}=s_{i}−s_{i−l }is the difference between the coordinate of the ith path point and, the coordinate of the ilth path point, and L is the forwardlooking distance of the mobile device at the current position that is equal to the adjustment forwardlooking distance calculated through the previous position.
the adjustment linear velocity, the adjustment forwardlooking distance, and the adjustment angular velocity can be calculated through the equations (6), (7), and (8), respectively.
where, V is the current linear velocity, V_{c }is the calculated adjustment linear velocity, L is the forwardlooking distance of the current position, L_{c }is the calculated adjustment forwardlooking distance that is taken as the forwardlooking distance when the mobile device is at the next position, ω_{c }is the adjustment linear velocity, and η is the deviation angle.
In this embodiment, by adding the penalty function (the penalty function is related to the curvature of the path) to the originally fixed forwardlooking distance, the stability of the control of the path tracking is improved. In the case that the robot is moved to a position near to the positions with large curvature, the penalty function is increased to reduce the forwardlooking distance so that the robot track the path in a closer manner and in a slower velocity to improve the stability of the control of the path tracking; in the case that the robot is moved to a position near to the positions with a small curvature, the penalty function allows the velocity of the robot to be increased to ensure the efficiency of the method. In this embodiment, it optimizes the forwardlooking distance and the movement velocity based on the curvature of the path near the robot. The forwardlooking distance and the movement velocity are optimized through the penalty function with the curvature as a variable, so that the robot can slow down the velocity and shorten the forwardlooking distance in case that the path curvature is large, thereby significantly improving the robustness of the path tracking the robot.
In this embodiment, the forwardlooking path point corresponding to the current position of the mobile device that is on the preset path is determined, and the adjustment velocity of the mobile device at the current position is determined based on the path curvature corresponding to the forwardlooking path point, which can determine the adjustment velocity of the mobile device based on the curvature of the path, so as to adjust the velocity of the mobile device, thereby improving the stability of path tracking of the mobile device at different path curvatures.
It should be understood that, the sequence of the serial number of the steps in the abovementioned embodiments does not mean the execution order while the execution order of each process should be determined by its function and internal logic, which should not be taken as any limitation to the implementation process of the embodiments.
As shown in
The first obtaining module 101 is configured to obtain a preset path and a current position of the mobile device.
The first processing module 102 is configured to determine a forwardlooking path point corresponding to the current position on the preset path.
The second obtaining module 103 is configured to obtain a path curvature corresponding to the forwardlooking path point.
The second processing module 104 is configured to determine an adjustment velocity of the mobile device at the current position based on the path curvature corresponding to the forwardlooking path point, and adjust a current velocity of the mobile device at the current position according to the adjustment velocity.
In one embodiment, the first processing module 102 can be configured to:
obtain a forwardlooking distance corresponding to the current position; and
select a first path point on the preset path as the forwardlooking path point, where a distance between the first path point and the current position is the forwardlooking distance corresponding to the current position.
In one embodiment, the first processing module 102 is configured to:
obtain a preset forwardlooking distance and taking the preset forwardlooking distance as the forwardlooking distance corresponding to the current position; or
obtain an adjustment forwardlooking distance corresponding to a previous position of the mobile device and taking the adjustment forwardlooking distance corresponding to the previous position as the forwardlooking distance corresponding to the current position.
In one embodiment, the second processing module 104 is configured to:
select at least one path point on a section of the preset path at which the forwardlooking path point is located; and
calculate the adjustment velocity of the mobile device at the current position based on the path curvature corresponding to each path point.
In one embodiment, the second processing module 104 is configured to:
search for a second path point corresponding to the current position, wherein the second path point is a vertical point on the preset path corresponding to the current position; and
select at least one path point on a section of the preset path between the second path point and the forwardlooking path point from the preset path.
In one embodiment, the second processing module 104 is configured to:
calculate the path curvature corresponding to each path point and a first distance corresponding to each path point, wherein the first distance corresponding to the path point is a distance between the path point and a previous path point;
calculate a product of an absolute value of the path curvature corresponding to each path point and the first distance corresponding to the path point, and summing the products of all the path points to obtain a sum of the products;
determine an adjustment coefficient based on the sum of the products; and
calculate the adjustment velocity of the mobile device at the current position based on the adjustment coefficient and a current velocity of the mobile device.
In one embodiment, the second processing module 104 is configured to:
calculate a difference between the path curvature of each path point and the path curvature of the previous path point to take as the path curvature corresponding to the path point.
In one embodiment, the second processing module 104 is configured to:
calculate a first ratio of the sum of the products to the forwardlooking distance, wherein the forwardlooking distance is a distance between the current position of the mobile device and the forwardlooking path point; and
determine the adjustment coefficient based on the first ratio.
In one embodiment, the second processing module 104 is configured to:
calculate the adjustment coefficient based on a penalty function formula and the first ratio, wherein the penalty function formula is:
where, P is the adjustment coefficient, and X is the first ratio.
In one embodiment, the current velocity includes a current line velocity, and the adjustment velocity includes an adjustment line velocity and an adjustment angular velocity; and the second processing module 104 is configured to:
calculate a product of the current linear velocity of the mobile device and the adjustment coefficient to obtain the adjustment linear velocity;
calculate a product of the forwardlooking distance and the adjustment coefficient to obtain the adjustment forwardlooking distance, wherein the forwardlooking distance is a distance between the current position of the mobile device and the forwardlooking path point; and
calculate the adjustment angular velocity based on the adjustment linear velocity, the adjustment forwardlooking distance, and a deviation angle, wherein the deviation angle is an included angle between a vector direction from the current position of the mobile device to the forwardlooking path point and a direction of the current linear velocity of the mobile device.
In one embodiment, the second processing module 104 is configured to:
calculate a second ratio of the adjustment linear velocity to the adjustment forwardlooking distance; and
calculate a product of the sine of the deviation angle and the second ratio to obtain the adjustment angular velocity.
In this embodiment, each of the abovementioned modules/units is implemented in the form of software, which can be computer program(s) stored in a memory of the path tracking apparatus 100 and executable on a processor of the path tracking apparatus 100. In other embodiments, each of the abovementioned modules/units may be implemented in the form of hardware (e.g., a circuit of the path tracking apparatus 100 which is coupled to the processor of the path tracking apparatus 100) or a combination of hardware and software (e.g., a circuit with a single chip microcomputer).
In this embodiment, the forwardlooking path point corresponding to the current position of the mobile device that is on the preset path is determined, and the adjustment velocity of the mobile device at the current position is determined based on the path curvature corresponding to the forwardlooking path point, which can determine the adjustment velocity of the mobile device based on the curvature of the path, so as to adjust the velocity of the mobile device, thereby improving the stability of path tracking of the mobile device at different path curvatures.
The mobile robot 11 may include, but is not limited to, the processor 110 and the storage 111. It can be understood by those skilled in the art that
The processor 110 may be a central processing unit (CPU), or be other general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a fieldprogrammable gate array (FPGA), or be other programmable logic device, a discrete gate, a transistor logic device, and a discrete hardware component. The general purpose processor may be a microprocessor, or the processor may also be any conventional processor.
The storage 111 may be an internal storage unit of the mobile robot 11, for example, a hard disk or a memory of the mobile robot 11. The storage 111 may also be an external storage device of the mobile robot 11, for example, a plugin hard disk, a smart media card (SMC), a secure digital (SD) card, flash card, and the like, which is equipped on the mobile robot 11. Furthermore, the storage 111 may further include both an internal storage unit and an external storage device, of the mobile robot 11. The storage 111 is configured to store the computer program 112 and other programs and data required by the mobile robot 11. The storage 111 may also be used to temporarily store data that has been or will be output.
Those skilled in the art may clearly understand that, for the convenience and simplicity of description, the division of the abovementioned functional units and modules is merely an example for illustration. In actual applications, the abovementioned functions may be allocated to be performed by different functional units according to requirements, that is, the internal structure of the device may be divided into different functional units or modules to complete all or part of the abovementioned functions. The functional units and modules in the embodiments may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit. The abovementioned integrated unit may be implemented in the form of hardware or in the form of software functional unit. In addition, the specific name of each functional unit and module is merely for the convenience of distinguishing each other and are not intended to limit the scope of protection of the present disclosure. For the specific operation process of the units and modules in the abovementioned system, reference may be made to the corresponding processes in the abovementioned method embodiments, and are not described herein.
In the abovementioned embodiments, the description of each embodiment has its focuses, and the parts which are not described or mentioned in one embodiment may refer to the related descriptions in other embodiments.
Those ordinary skilled in the art may clearly understand that, the exemplificative units and steps described in the embodiments disclosed herein may be implemented through electronic, hardware or a combination of computer software and electronic hardware. Whether these functions are implemented through hardware or software depends on the specific application and design constraints of the technical schemes. Those ordinary skilled in the art may implement the described functions in different manners for each particular application, while such implementation should not be considered as beyond the scope of the present disclosure.
In the embodiments provided by the present disclosure, it should be understood that the disclosed apparatus/mobile robot and method may be implemented in other manners. For example, the abovementioned apparatus/mobile robot embodiment is merely exemplary. For example, the division of modules or units is merely a logical functional division, and other division manner may be used in actual implementations, that is, multiple units or components may be combined or be integrated into another system, or some of the features may be ignored or not performed. In addition, the shown or discussed mutual coupling may be direct coupling or communication connection, and may also be indirect coupling or communication connection through some interfaces, devices or units, and may also be electrical, mechanical or other forms.
The units described as separate components may or may not be physically separated. The components represented as units may or may not be physical units, that is, may be located in one place or be distributed to multiple network units. Some or all of the units may be selected according to actual needs to achieve the objectives of this embodiment.
In addition, each functional unit in each of the embodiments of the present disclosure may be integrated into one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit. The abovementioned integrated unit may be implemented in the form of hardware or in the form of software functional unit.
When the integrated module/unit is implemented in the form of a software functional unit and is sold or used as an independent product, the integrated module/unit may be stored in a nontransitory computerreadable storage medium. Based on this understanding, all or part of the processes in the method for implementing the abovementioned embodiments of the present disclosure are implemented, and may also be implemented by instructing relevant hardware through a computer program. The computer program may be stored in a nontransitory computerreadable storage medium, which may implement the steps of each of the abovementioned method embodiments when executed by a processor. In which, the computer program includes computer program codes which may be the form of source codes, object codes, executable files, certain intermediate, and the like. The computerreadable medium may include any primitive or device capable of carrying the computer program codes, a recording medium, a USB flash drive, a portable hard disk, a magnetic disk, an optical disk, a computer memory, a readonly memory (ROM), a random access memory (RAM), electric carrier signals, telecommunication signals and software distribution media. It should be noted that the content contained in the computer readable medium may be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to the legislation and patent practice, a computer readable medium does not include electric carrier signals and telecommunication signals.
The abovementioned embodiments are merely intended for describing but not for limiting the technical schemes of the present disclosure. Although the present disclosure is described in detail with reference to the abovementioned embodiments, it should be understood by those skilled in the art that, the technical schemes in each of the abovementioned embodiments may still be modified, or some of the technical features may be equivalently replaced, while these modifications or replacements do not make the essence of the corresponding technical schemes depart from the spirit and scope of the technical schemes of each of the embodiments of the present disclosure, and should be included within the scope of the present disclosure.