A path following method and system for a two-wheel differential mobile robot

Abstract

The present invention relates to a path following method and system of a two-wheel differential mobile robot, comprising the following steps: S1: obtaining a target path according to a navigation system; S2: updating the current position of the robot, and obtaining the path point closest to the target path; S3: calculating the robot's foresight distance and determining the foresight point, and calculating the curvature according to the robot's current position and the foresight point; S4: determining the desired linear velocity command according to the road conditions, and applying left and right wheel motor acceleration constraints to the desired linear velocity command to generate the final linear velocity command; S5: calculating the angular velocity command according to the final linear velocity command and the curvature, converting the linear velocity command and the angular velocity command into left and right wheel motor speed commands and sending them to the motor; S6: repeating steps S2-S5 until the robot reaches the end of the target path. The path following method and system of the two-wheel differential mobile robot provided by the present invention have a smoother motion control effect, and to a certain extent, ensure the path following accuracy of the robot on a complex path.

Description

Technical Field

[0001] The present invention relates to the technical field of robot motion control, and in particular to a path following method and system for a two-wheel differential mobile robot. Background Art

[0002] In the prior art, the common method for a two-wheel differential mobile robot to follow a path is as follows: based on experience and testing, manually select an appropriate foresight distance d to determine the foresight point Z, find the path point P closest to the foresight point Z, c is the curvature at the path point P, and e is the distance deviation between the foresight point and the path point P (refer to Figure 1 ).

[0003] The linear speed control command v is inversely proportional to the curvature c, thus realizing the strategy of accelerating on straight roads and decelerating on curves. The calculation formula of v is as follows:

[0004] v = k*c (0 < k < 1)

[0005] The angular velocity control command ω is calculated by the proportional integral differential controller (PID controller). In the discrete time digital control system, the calculation formula of ω is as follows:

[0006]

[0007] Where K P is the proportionality coefficient; K I is the integral coefficient; K D is the differential coefficient.

[0008] These PID controller coefficients need to be adjusted manually to achieve satisfactory results. The usual method of adjusting parameters is: first adjust K I and K D Initialize to 0, then increase K P , until the system starts to oscillate. Then start adjusting K D , until the oscillation is damped in most cases. Finally, adjust K I To eliminate static deviation.

[0009] Problems with the above existing technical solutions:

[0010] 1. The PID controller coefficients need to be adjusted manually. Even after multiple adjustments and tests to iterate the coefficients, the path following accuracy is still not very high, especially on curved paths with large curvatures.

[0011] 2. The PID controller coefficient is highly correlated with the linear speed v. A set of PID coefficients cannot provide good path following accuracy at high, medium and low speed levels. Different PID coefficients are usually required for different speed levels, which greatly increases the debugging workload and is not easy to deploy and use.

[0012] 3. Failure to consider dynamic constraints, that is, failure to consider the dynamic performance indicators of the left and right wheel motors (such as maximum acceleration). Under complex road conditions, the robot's motion control effect will be jerky and the acceleration will be too large. Summary of the invention

[0013] In view of the deficiencies in the prior art, the present invention provides a path following method and system for a two-wheel differential mobile robot, which has a smoother motion control effect and, to a certain extent, ensures the path following accuracy of the robot on a complex path, thereby improving efficiency.

[0014] In order to achieve the purpose of the present invention, the present invention provides a path following method of a two-wheel differential mobile robot, comprising the following steps:

[0015] S1: Obtain the target path according to the navigation system;

[0016] S2: Update the current position of the robot and obtain the path point closest to the target path;

[0017] S3: Calculate the robot's forward sight distance and determine the forward sight point, and calculate the curvature according to the robot's current position and the forward sight point;

[0018] S4: determining a desired linear speed command according to the road conditions, and applying left and right wheel motor acceleration constraints to the desired linear speed command to generate a final linear speed command;

[0019] S5: Calculate the angular velocity command according to the final linear velocity command and the curvature, convert the linear velocity command and the angular velocity command into left and right wheel motor speed commands and send them to the motors;

[0020] S6: Repeat steps S2-S5 until the robot reaches the end of the target path.

[0021] Preferably, the step S1 specifically includes:

[0022] A target path is obtained according to the navigation system, wherein the target path includes a plurality of path points, wherein each path point includes:

[0023] The x-coordinate and y-coordinate in the global coordinate system;

[0024] The orientation of the target path in the global coordinate system, and the curvature of each path point on the target path.

[0025] Preferably, the specific steps of calculating the robot's forward sight distance and determining the forward sight point in step S3 include:

[0026] The formula for calculating the robot's forward sight distance is:

[0027] l=k*v

[0028] Among them, k is the adjustable proportional coefficient, and v is the current actual linear velocity of the robot;

[0029] Taking the path point closest to the target path as the reference, the distance between the robot and each path point is calculated. When the calculated distance between the robot and one of the path points is greater than l, the path point is used as the foresight point.

[0030] Preferably, calculating the curvature according to the current position and the foresight point of the robot in step S3 specifically includes:

[0031] The curvature c is calculated based on the arc of the robot's current position and the foresight point (x, y). The calculation formula is:

[0032]

[0033] Among them, r is the radius of the arc, x is the X-axis coordinate of the foresight point in the robot coordinate system, and y is the Y-axis coordinate of the foresight point in the robot coordinate system.

[0034] Preferably, the specific steps of step S4 are:

[0035] Determine the desired linear speed command, the calculation formula is:

[0036] v desire =min(v1,v2,v3)

[0037] By calculating the curvature of all path points on a certain section of the robot's forward-looking direction and finding the maximum value of the curvature, the linear velocity command V1 is inversely proportional to the maximum curvature;

[0038] By calculating the distance between all path points on a certain section of the robot's forward-looking path and the obstacles, and finding the minimum distance, the linear speed command V2 is inversely proportional to the minimum distance;

[0039] By calculating the distance between the current position of the robot and the end point of the target path, the linear speed command V3 is inversely proportional to the distance;

[0040] The left and right wheel motor acceleration constraints are applied to the desired linear speed command to obtain the final linear speed command.

[0041] Preferably, applying left and right wheel motor acceleration constraints to the desired linear speed command to obtain the final linear speed command specifically includes:

[0042] Taking steps S2-S5 as a control cycle, the value range of the linear speed instruction of the current control cycle is calculated, and the value range constraint is imposed on the desired linear speed instruction, so as to obtain the final linear speed instruction, and the value range calculation formula is:

[0043]

[0044] Among them, subscript k is the current control cycle, subscript k-1 is the previous control cycle, V k is the linear speed command of the current control cycle, a is the maximum acceleration of the left and right wheels determined by testing the load step response of the left and right wheel motors, R is the left wheel of the robot, L is the right wheel of the robot, and △t represents the control cycle.

[0045] Preferably, the imposing a value range constraint on the desired linear speed instruction specifically includes:

[0046] When the imposed value is less than the lower limit of the interval, the lower limit of the interval is used for constraint;

[0047] When the imposed value is greater than the upper limit of the interval, the upper limit of the interval is used for constraint;

[0048] When the applied value is within the interval, it remains unchanged.

[0049] Preferably, the step S5 specifically includes:

[0050] The angular velocity command is calculated according to the final linear velocity command and the curvature. The calculation formula of the angular velocity command is:

[0051] ω cmd =c*v cmd

[0052] Where c is the curvature, V cmd is the final line speed instruction;

[0053] The linear velocity command and angular velocity command are converted into left and right wheel motor speed commands and sent to the motors. The conversion formula is:

[0054]

[0055] Where c is the curvature, r is the radius, ω cmd is the angular velocity command, V cmd is the final linear speed command, d is half of the wheel spacing, VR cm d is the right wheel linear speed command, VL cm d is the left wheel linear speed command.

[0056] Preferably, the present invention also provides a path following system for a two-wheel differential mobile robot, comprising:

[0057] Acquisition module: used to obtain the target path, the current position of the robot and the coordinates of each path point on the target path;

[0058] Control module: calculates the robot's forward sight distance and determines the forward sight point, calculates the curvature according to the robot's current position and forward sight point, determines the desired linear speed command according to the road conditions, and applies left and right wheel motor acceleration constraints to the desired linear speed command to generate the final linear speed command, calculates the angular speed command according to the final linear speed command and the curvature, and converts the linear speed command and the angular speed command into left and right wheel motor speed commands;

[0059] Drive module: Receives left and right wheel motor speed instructions from the control module and drives the robot.

[0060] Preferably, in the control module, calculating the robot's forward sight distance and determining the forward sight point specifically includes:

[0061] The formula for calculating the robot's forward sight distance is:

[0062] l=k*v

[0063] Among them, k is the adjustable proportional coefficient, and v is the current actual linear velocity of the robot;

[0064] Taking the path point closest to the target path as the reference, the distance between the robot and each path point is calculated. When the calculated distance between the robot and one of the path points is greater than l, the path point is used as the foresight point.

[0065] The beneficial effects of the present invention are as follows: the path following method and system of the two-wheel differential mobile robot provided by the present invention have a smoother motion control effect and to a certain extent ensure the path following accuracy of the robot on a complex path, thereby improving efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] The above and other purposes, features and advantages of the present invention will become more clear by more specific description of the preferred embodiments of the present invention shown in the accompanying drawings. The same reference numerals indicate the same parts in all the accompanying drawings, and the accompanying drawings are not deliberately scaled to the actual size, and the focus is on illustrating the main purpose of the present invention.

[0067] Figure 1 It is a schematic diagram of an embodiment provided in the background technology;

[0068] Figure 2 A schematic flow chart of a path following method for a two-wheel differential mobile robot provided by an embodiment of the present invention;

[0069] Figure 3 A schematic diagram of curvature calculation of a robot in a target path following process provided by an embodiment of the present invention;

[0070] Figure 4 A schematic flow chart of a kinematic model of a two-wheel differential base provided in an embodiment of the present invention;

[0071] Figure 5 A schematic diagram of a specific flow chart of a path following method for a two-wheel differential mobile robot provided by an embodiment of the present invention; DETAILED DESCRIPTION

[0072] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0073] Please refer to Figure 2-5 The embodiment of the present invention provides a path following method of a two-wheel differential mobile robot, comprising the following steps:

[0074] S1: Obtain the target path according to the navigation system;

[0075] S2: Update the current position of the robot and obtain the path point closest to the target path;

[0076] S3: Calculate the robot's forward sight distance and determine the forward sight point, and calculate the curvature according to the robot's current position and the forward sight point;

[0077] S4: determining a desired linear speed command according to the road conditions, and applying left and right wheel motor acceleration constraints to the desired linear speed command to generate a final linear speed command;

[0078] S5: Calculate the angular velocity command according to the final linear velocity command and the curvature, convert the linear velocity command and the angular velocity command into left and right wheel motor speed commands and send them to the motors;

[0079] S6: Repeat steps S2-S5 until the robot reaches the end of the target path (take steps S2-S5 as a control cycle. When the next control cycle comes, first use step S2 to update the robot position and obtain the path point closest to the force target path, and then repeat steps S3-S5 to calculate the motor speed command. The above control cycle is executed cyclically, and the two-wheel differential mobile robot can complete high-precision tracking of the target path.).

[0080] Please refer to Figure 2-5 In the preferred embodiment, the curvature of the path is calculated first, and then the speed instruction is determined according to the environment.

[0081] ω cmd =c*v cmd

[0082] Once the angular velocity command is calculated, the turning radius of the robot is always determined for the same path regardless of whether the linear velocity command is high or low.

[0083] The path following method for a two-wheeled differential mobile robot provided in the present application has high path following accuracy even when faced with relatively complex paths, such as large arc paths (it can solve the technical problem in the prior art that the PID controller coefficients need to be manually adjusted, and even after multiple adjustments and tests to iterate the coefficients, the path following accuracy is still not particularly high, especially on curved paths with large curvatures).

[0084] The present invention provides a path following method for a two-wheel differential mobile robot. During actual operation, a planner in a navigation system of the two-wheel differential mobile robot inputs a target path consisting of discrete points and the position and posture of the robot in a world coordinate system to the method. The planner uses pre-calculated data (the foresight distance is used to determine the foresight point Z, the expected linear velocity command is preset to calculate the final linear velocity command of the robot, and the angular velocity command is calculated based on the final linear velocity command) to control the left and right wheels of the robot to perform corresponding movements, thereby achieving the purpose of path following.

[0085] The beneficial effect of the present invention is that by determining the foresight point and calculating the curvature of the path according to the foresight point, and then determining the linear speed instruction according to the environment, the robot can ensure the accuracy of its path following to a certain extent when performing path following.

[0086] Please refer to Figure 2-5 In a preferred embodiment, the step S1 specifically includes:

[0087] A target path is obtained according to a navigation system, wherein the target path includes a plurality of path points (the target path is composed of a series of discrete path points), wherein each path point includes:

[0088] The x-coordinate and y-coordinate in the global coordinate system;

[0089] The orientation of the target path in the global coordinate system, and the curvature of each path point on the target path.

[0090] Please refer to Figure 2-3 In a preferred embodiment, the specific steps of calculating the robot's forward sight distance and determining the forward sight point in step S3 include:

[0091] The formula for calculating the robot's forward sight distance is:

[0092] l=k*v

[0093] Wherein, k is an adjustable proportional coefficient (parameter k is the only key parameter that determines the path following accuracy. A suitable parameter k can have a high path following accuracy, with fewer parameters and simple parameter adjustment. Through a suitable adjustable proportional coefficient, the technical problems of many parameters and complex parameter adjustment in the prior art can be solved), and v is the current actual linear speed of the robot;

[0094] Taking the path point closest to the target path as the reference (starting from the path point closest to the robot and searching forward), calculate the distance between the robot and each path point. When the calculated distance between the robot and one of the path points is greater than l, use that path point as the foresight point Z.

[0095] Please refer to Figure 3 In a further preferred embodiment, the curvature is calculated according to the current position and the foresight point of the robot in step S3, specifically comprising:

[0096] According to the current position of the robot (based on the center of the robot) and the arc of the foresight point Z (x, y) (the coordinates of the foresight point Z in the global coordinate system), the curvature c is calculated (the curvature of the arc connecting the center of the robot and the foresight point Z is calculated according to the geometric relationship. The circle where the arc is located is the circle of the robot's instantaneous circular motion. The circle is tangent to the X-axis of the robot's coordinate system, so the circle is uniquely determined. According to the sine theorem, the curvature c can be calculated). The calculation and derivation formula is:

[0097]

[0098]

[0099]

[0100]

[0101] Among them, r is the radius of the arc, x is the X-axis coordinate of the foresight point in the robot coordinate system, and y is the Y-axis coordinate of the foresight point in the robot coordinate system.

[0102] Please refer to Figure 2-5 In a further preferred embodiment, the specific steps of step S4 are:

[0103] Determine the desired linear speed command, the calculation formula is:

[0104] v desire =min(v1,v2,v3)

[0105] By calculating the curvature of all path points on a certain section of the robot's forward-looking direction and finding the maximum value of the curvature, the linear speed command V1 is inversely proportional to the maximum curvature (thus achieving the strategy of accelerating on straight roads and decelerating on curves);

[0106] By calculating the distance between all path points on a certain section of the robot's forward-looking path and the obstacle, and finding the minimum distance, the linear speed command V2 is inversely proportional to the minimum distance (reducing the speed when approaching an obstacle to ensure safety);

[0107] By calculating the distance between the robot's current position and the end point of the target path, the linear speed command V3 is inversely proportional to the distance (so that the robot can stop at the end point);

[0108] By calculating the curvature of each path point on the target path, the distance between the path point and the obstacle, and the distance between the robot's current position and the end point of the target path, the robot's accuracy can be improved, and the robot's efficiency can also be improved.

[0109] The left and right wheel motor acceleration constraints are applied to the desired linear speed command to obtain the final linear speed command (which can ensure that the robot can move better in more complex paths).

[0110] Please refer to Figure 2-5 In a preferred embodiment, applying left and right wheel motor acceleration constraints to the desired linear speed command to obtain the final linear speed command specifically includes:

[0111] Taking steps S2-S5 as a control cycle, the value range of the linear speed command of the current control cycle is calculated, and the value range constraint is imposed on the desired linear speed command (by imposing the value range, it can ensure that the motion control effect of the robot actuator (left and right wheel motors) is smoother, without jamming, and the imposed speed will not be too large), and the final linear speed command can be obtained. The value range calculation formula is:

[0112]

[0113] Among them, subscript k is the current control cycle, subscript k-1 is the previous control cycle, V k is the linear speed command of the current control cycle, a is the maximum acceleration of the left and right wheels determined by testing the load step response of the left and right wheel motors, R is the left wheel of the robot, L is the right wheel of the robot, and △t represents the control cycle.

[0114] Linear speed command V of the current control cycle k The acceleration constraints of the left and right wheel motors need to be met (the derivation formula is based on Figure 4 The kinematic model of the two-wheel differential chassis is derived. For details, please refer to Figure 4 The corresponding derivation formula) The derivation process (interval calculation formula) is as follows:

[0115]

[0116]

[0117]

[0118]

[0119] Solving the above inequality, we can get the linear speed command V that satisfies the left and right wheel motor acceleration constraints. k The possible value range of .

[0120] Please refer to Figure 2-5 In a further preferred embodiment, the step of applying a value range constraint to the desired linear speed instruction specifically includes:

[0121] When the imposed value is less than the lower limit of the interval, the lower limit of the interval is used for constraint;

[0122] When the imposed value is greater than the upper limit of the interval, the upper limit of the interval is used for constraint;

[0123] When the applied value is within the interval, it remains unchanged.

[0124] Please refer to Figure 2-5 In a preferred embodiment, step S5 specifically includes:

[0125] The angular velocity command is calculated according to the final linear velocity command and the curvature. The calculation formula of the angular velocity command is:

[0126] ω cmd =c*v cmd

[0127] Where c is the curvature, V cmd is the final line speed instruction;

[0128] Please refer to Figure 4 , the linear velocity calculation formula of the robot in circular motion is:

[0129] v=ω*r

[0130] The angular velocity can be calculated by the angular velocity and the curvature of the path. The calculation formula is:

[0131]

[0132] The speed of the left and right wheels can be calculated by the angular velocity and linear velocity. The calculation formula is:

[0133]

[0134] Where ω and v are angular velocity and linear velocity respectively, V L and V R are the speeds of the left and right wheels respectively, d is half of the wheel spacing, r is the radius of the instantaneous circular motion, and c is the curvature of the instantaneous circular motion.

[0135] The linear velocity command and angular velocity command are converted into left and right wheel motor speed commands and sent to the motors. The conversion formula is:

[0136]

[0137] Where c is the curvature, r is the radius (instantaneous circular motion), o is the center of the circle, ω cmd is the angular velocity command, V cmd is the final linear speed command, d is half of the wheel spacing (between the left and right wheels), V Rcmd is the right wheel linear speed command, V Lcmd is the left wheel linear speed command. In special complex paths, such as S-curves, the two intervals in the above formula may not intersect. This means that the dynamic performance index (maximum acceleration a) of the motor cannot meet the requirements of complex road conditions. At this time, you can replace the left and right wheel motors with stronger performance, or reduce the robot load, or the navigation system planner can reduce the complexity of the path when planning the path.

[0138] Please refer to Figure 2-5 In a preferred embodiment, the present invention further provides a path following system for a two-wheel differential mobile robot, comprising:

[0139] Acquisition module: used to obtain the target path, the current position of the robot and the coordinates of each path point on the target path;

[0140] Control module: calculates the robot's forward sight distance and determines the forward sight point, calculates the curvature according to the robot's current position and forward sight point, determines the desired linear speed command according to the road conditions, and applies left and right wheel motor acceleration constraints to the desired linear speed command to generate the final linear speed command, calculates the angular speed command according to the final linear speed command and the curvature, and converts the linear speed command and the angular speed command into left and right wheel motor speed commands;

[0141] Drive module: Receives left and right wheel motor speed instructions from the control module and drives the robot.

[0142] Please refer to Figure 2-5 In a preferred embodiment, in the control module, calculating the robot's forward sight distance and determining the forward sight point specifically includes:

[0143] The formula for calculating the robot's forward sight distance is:

[0144] l=k*v

[0145] Among them, k is the adjustable proportional coefficient, and v is the current actual linear velocity of the robot;

[0146] Taking the path point closest to the target path as the reference, the distance between the robot and each path point is calculated. When the calculated distance between the robot and one of the path points is greater than l, the path point is used as the foresight point.

[0147] The two-wheel differential robot and the two-wheel differential chassis in the present application are widely used in the field of mobile robots due to their simple structure and low cost, such as cleaning robots (sweeping robots, disinfection robots) and service robots (delivery robots, leading robots).

[0148] The path following algorithm for the two-wheel differential mobile robot navigation system provided by the present invention complies with kinematic constraints and dynamic constraints, can smoothly follow the target path with high accuracy, and has strong robustness after long-term actual machine testing, and can adapt to various paths such as straight roads and complex curves.

[0149] The path following method and system for a two-wheel differential mobile robot provided in the present application mainly solve the technical problems existing in the path following technology in the prior art: such as low path following accuracy, the need to adapt parameters for different speed gears, complex parameter adjustment, time-consuming and labor-intensive; the operation and control effect is jerky and not smooth, and the acceleration is too large.

[0150] The beneficial effects of the present invention are as follows: the present invention provides a path following method and system for a two-wheel differential mobile robot, the motion control effect is smoother, and the path following accuracy of the robot on a complex path is guaranteed to a certain extent, thereby improving efficiency.

[0151] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A path following method for a two-wheel differential mobile robot, characterized in that: The steps include: S1: Obtain the target path according to the navigation system; S2: Update the current position of the robot and obtain the path point closest to the target path; S3: Calculate the robot's forward sight distance and determine the forward sight point, and calculate the curvature according to the robot's current position and the forward sight point; S4: determining a desired linear speed command according to the road conditions, and applying left and right wheel motor acceleration constraints to the desired linear speed command to generate a final linear speed command; S5: Calculate the angular velocity command according to the final linear velocity command and the curvature, convert the linear velocity command and the angular velocity command into left and right wheel motor speed commands and send them to the motors; S6: Repeat steps S2-S5 until the robot reaches the end of the target path.

2. The path following method according to claim 1, characterized in that: The step S1 specifically includes: A target path is obtained according to the navigation system, wherein the target path includes a plurality of path points, wherein each path point includes: The x-coordinate and y-coordinate in the global coordinate system; The orientation of the target path in the global coordinate system, and the curvature of each path point on the target path.

3. The path following method according to claim 1, characterized in that: The specific steps of calculating the robot's forward sight distance and determining the forward sight point in step S3 include: The formula for calculating the robot's forward sight distance is: l=k*v Among them, k is the adjustable proportional coefficient, and v is the current actual linear velocity of the robot; Taking the path point closest to the target path as the reference, the distance between the robot and each path point is calculated. When the calculated distance between the robot and one of the path points is greater than l, the path point is used as the foresight point.

4. The path following method according to claim 1, characterized in that: The step S3 of calculating the curvature according to the current position and the foresight point of the robot specifically includes: The curvature c is calculated based on the arc of the robot's current position and the foresight point (x, y). The calculation formula is: Among them, r is the radius of the arc, x is the X-axis coordinate of the foresight point in the robot coordinate system, and y is the Y-axis coordinate of the foresight point in the robot coordinate system.

5. The path following method according to claim 1, characterized in that: The specific steps of determining the expected linear speed instruction according to the road conditions in step S4 are: Determine the desired linear speed command, the calculation formula is: v desire =min(v1,v2,v3) By calculating the curvature of all path points on a certain section of the robot's forward-looking direction and finding the maximum value of the curvature, the linear velocity command V1 is inversely proportional to the maximum curvature; By calculating the distance between all path points on a certain section of the robot's forward-looking path and the obstacles, and finding the minimum distance, the linear speed command V2 is inversely proportional to the minimum distance; By calculating the distance between the current position of the robot and the end point of the target path, the linear speed instruction V3 is inversely proportional to the distance.

6. The path following method according to claim 1, characterized in that: In step S4, applying left and right wheel motor acceleration constraints to the desired linear speed command to generate the final linear speed command specifically includes: Taking steps S2-S5 as a control cycle, the value range of the linear speed instruction of the current control cycle is calculated, and the value range constraint is imposed on the desired linear speed instruction, so as to obtain the final linear speed instruction, and the value range calculation formula is: Among them, subscript k is the current control cycle, subscript k-1 is the previous control cycle, V k is the linear speed command of the current control cycle, a is the maximum acceleration of the left and right wheels determined by testing the load step response of the left and right wheel motors, R is the left wheel of the robot, L is the right wheel of the robot, and △t represents the control cycle.

7. The path following method according to claim 6, characterized in that: The imposing of a value range constraint on the desired linear speed instruction specifically includes: When the imposed value is less than the lower limit of the interval, the lower limit of the interval is used for constraint; When the imposed value is greater than the upper limit of the interval, the upper limit of the interval is used for constraint; When the applied value is within the interval, it remains unchanged.

8. The path following method according to claim 1, characterized in that: The step S5 specifically includes: The angular velocity command is calculated according to the final linear velocity command and the curvature. The calculation formula of the angular velocity command is: oh cmd =c*v cmd Where c is the curvature, V cmd is the final line speed instruction; The linear velocity command and angular velocity command are converted into left and right wheel motor speed commands and sent to the motors. The conversion formula is: Where c is the curvature, r is the radius, ω cmd is the angular velocity command, V cmd is the final linear speed command, d is half of the wheel spacing, VR cmd is the right wheel linear speed command, VL cmd It is the left wheel linear speed instruction.

9. A path following system for a two-wheel differential mobile robot, characterized in that: include: Acquisition module: used to obtain the target path, the current position of the robot and the coordinates of each path point on the target path; Control module: calculates the robot's forward sight distance and determines the forward sight point, calculates the curvature according to the robot's current position and forward sight point, determines the desired linear speed command according to the road conditions, and applies left and right wheel motor acceleration constraints to the desired linear speed command to generate the final linear speed command, calculates the angular speed command according to the final linear speed command and the curvature, and converts the linear speed command and the angular speed command into left and right wheel motor speed commands; Drive module: Receives left and right wheel motor speed instructions from the control module and drives the robot.

10. The path following system according to claim 9, characterized in that: In the control module, calculating the robot's forward sight distance and determining the forward sight point specifically includes: The formula for calculating the robot's forward sight distance is: l=k*v Among them, k is the adjustable proportional coefficient, and v is the current actual linear velocity of the robot; Taking the path point closest to the target path as the reference, the distance between the robot and each path point is calculated. When the calculated distance between the robot and one of the path points is greater than l, the path point is used as the foresight point.

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