Laser navigation precision improving method
By introducing virtual target points into the laser navigation system of AGV vehicles and adjusting the response range of the steering wheel angle, the problem of path offset when traditional laser navigation AGV vehicles move over long distances is solved, and higher-precision navigation control is achieved.
Patent Information
- Application Number
- CN202411677862.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-22
- Publication Date
- 2025-02-18
AI Technical Summary
Traditional laser navigation AGV vehicles cannot guarantee the accuracy of the middle section of the route when moving long distances, resulting in vehicle path offset, which is especially unacceptable in high-precision transportation scenarios.
Virtual target points are introduced, and by setting virtual points on the vehicle theoretical path, adjusting the response range of the steering wheel angle, thereby achieving more precise path control. The specific steps include: using the starting point and the target point as the theoretical path, setting the convergence distance L, and the intersection point with the theoretical path as the center, adjusting the vehicle to advance to the second virtual point, forming a fitted path.
Through the introduction of virtual target points, the actual path of the AGV vehicle can fit the theoretical path more accurately, reducing path drift and jumping of the steering wheel control angle, and improving navigation accuracy.
Smart Images
Figure CN119469190A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of AGV transportation technology, and in particular to a method for improving laser navigation accuracy. Background Art
[0002] AGV conveyor vehicles are common logistics and transportation equipment in the field of automated production and manufacturing. Various manufacturing industries, from air conditioners and televisions to automobiles, need to organize production around conveying equipment. The importance of conveying equipment in the field of production and manufacturing is irreplaceable. Laser navigation AGV relies on laser sensors as position feedback devices. It plans a straight path through the current vehicle coordinates and the destination coordinates of the vehicle. The AGV adjusts the direction of the vehicle according to this path to move toward the target. This solution can ensure that the vehicle eventually moves to the target coordinates, but due to the control accuracy of the wheel angle, the accuracy limitations of the laser navigation sensor, and the stability of the positioning data, it is impossible to ensure that the entire route remains on the predetermined route, especially when encountering long-distance movement. The accuracy of the middle section of the route cannot be guaranteed. In some high-precision transportation and movement scenarios, the deviation of the vehicle path is unacceptable. Specifically, such as Figure 1 As shown in the figure, the traditional laser navigation AGV usually forms a straight line between the starting point (or the current real-time position of the AGV) and the target point. The vehicle controls the angle of the wheel steering wheel based on this straight angle, so that the entire vehicle moves to the target point. This control is perfect in theory, but due to the influence of the vehicle's steering wheel angle 0 position calibration, angle control accuracy, and positioning accuracy of the laser navigation sensor, the vehicle cannot move perfectly along the theoretical path. It has the following defects:
[0003] 1. When the distance between the starting point and the target point is too far, such as Figure 1 The AGV vehicle shown is at position A, and the theoretical route a is calculated. However, due to the control accuracy error of the steering wheel angle, the vehicle moves along the offset route b. At this time, due to the long distance between the current position (starting point) and the target point of the vehicle, the vehicle is at position B after a short displacement of L1. The theoretical calculation only shows a small angle adjustment of the steering wheel control angle, and it is expected to move along the theoretical route c. However, since the adjustment is affected by the control accuracy of the steering wheel angle, the small angle adjustment cannot be reflected on the steering wheel at all, which causes the vehicle to continue to deviate from the theoretical path a, and appear in a state similar to the offset route b (offset route b is only a possibility). Only when the actual position of the vehicle deviates greatly from the theoretical route, the adjustment of the vehicle's steering wheel angle can be reflected in the vehicle operation.
[0004] 2. When the starting point and the target point are too close, the vehicle's position changes, which will cause a large adjustment of the steering wheel control angle, such as Figure 1As shown in the figure, due to the positioning accuracy limitation of the laser navigation sensor, even if the vehicle is stationary, there are small distance jumps in the real-time position. Assuming that the vehicle position jumps between position C and position D, although the L2 jump is very small, such jumps will appear as large angle adjustments of the steering wheel in theoretical calculations. For example, the theoretical route d will be generated at position D. This situation becomes more and more significant when the vehicle is closer to the target endpoint (such as more than ten centimeters). The large angle jump of the steering wheel angle calculation result will cause the vehicle to stop in place and keep adjusting the steering wheel angle, or even cause the steering wheel angle to never be adjusted to the right position.
[0005] Therefore, how to improve the control accuracy of the navigation path and achieve high-precision navigation of the entire route is an issue that technical personnel in this field need to consider. Summary of the invention
[0006] The purpose of the present invention is to provide a method for improving the accuracy of laser navigation, which introduces a virtual target point on the theoretical path of the entire vehicle movement to control the angle adjustment of the steering wheel within a suitable response range, and solve the steering wheel control problem when the vehicle is far away from or close to the actual target point. In addition, it solves the problem of deviation between the actual path of the AGV vehicle and the theoretical path.
[0007] The technical solution of the present invention is: a method for improving laser navigation accuracy, comprising the following steps:
[0008] S1. Take the line connecting the starting point and the target point as the theoretical path, take the current position of the vehicle as the reference point, draw a perpendicular line to the theoretical path of the vehicle, and the intersection of the perpendicular line and the theoretical path is the first virtual point;
[0009] S2, setting the convergence distance L as the radius, and taking the first virtual point as the center of the circle, obtaining the intersection of the circle and the theoretical path as the second virtual point, and adjusting the vehicle to move toward the second virtual point to form a fitting path;
[0010] S3. When the distance between the vehicle and the target point is less than the convergence distance L, the second virtual point is set on the extension line of the theoretical path, and the vehicle continues to move toward the second virtual point, and the distance between the vehicle and the theoretical target point is calculated at all times. When the vehicle approaches the theoretical target point, the vehicle reaches the destination and stops moving.
[0011] Preferably, the fitting path is a real-time path curve formed by a plurality of waypoints of the AGV vehicle moving toward the second virtual point.
[0012] Preferably, in step S2, the angle between the theoretical path and the actual forward direction path of the vehicle is a deviation angle φ, and the vehicle adjusts the forward direction in real time according to the deviation angle φ.
[0013] Preferably, the convergence distance L is proportional to the driving speed of the vehicle. The greater the driving speed of the vehicle, the greater the convergence radius.
[0014] Preferably, in step S3, the convergence distance L is reduced to l, so that l is smaller than L and greater than 0.
[0015] Compared with the prior art, the advantages of the present invention are:
[0016] (1) The entire navigation algorithm continuously iterates and calculates virtual interpolation points, so that the AGV fits the theoretical route throughout the entire walking process, and the vehicle path drifts and the steering wheel control angle jumps due to the distance of the target point. At the same time, there is no need to add hardware. Only the adjustment of the navigation patrol line accuracy algorithm can achieve the adjustment of the path accuracy of the AGV vehicle operation, which increases the transportation accuracy without increasing the operating cost. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:
[0018] Figure 1 A schematic diagram of the conventional laser navigation vehicle path of the present invention;
[0019] Figure 2 This is a schematic diagram of vehicle movement after the laser navigation accuracy is improved according to the present invention;
[0020] Figure 3 A schematic diagram of a reference coordinate system for the calculation process of the present invention;
[0021] Figure 4 The figure is a flowchart of the navigation method of the present invention. DETAILED DESCRIPTION
[0022] The present invention is further described in detail below in conjunction with specific embodiments:
[0023] like Figure 2 As shown, a method for improving laser navigation accuracy comprises the following steps:
[0024] S1. Take the line connecting the starting point and the target point as the theoretical path, take the current position of the vehicle as the reference point, draw a perpendicular line to the theoretical path of the vehicle, and the intersection of the perpendicular line with the theoretical path is the first virtual point. That is, the first virtual point is the foot point of the perpendicular line between the real-time position of the vehicle and the theoretical route.
[0025] S2, set the convergence distance L as the radius, and take the first virtual point as the center of the circle, and obtain the intersection of the circle and the theoretical path as the second virtual point, and the vehicle continues to move towards the second virtual point. In this process, the driving path of the AGV vehicle converges on the theoretical route, and this method is iterated repeatedly so that the actual running path of the vehicle infinitely fits the theoretical path to form a fitting path, that is, the fitting path is a real-time path curve formed by multiple passing points of the AGV vehicle moving towards the second virtual point.
[0026] In the direction adjustment of the AGV vehicle, the angle between the theoretical path and the actual forward direction of the vehicle is the deviation angle φ, and the vehicle adjusts its forward direction in real time according to the deviation angle φ. Among them, the angle of the AGV vehicle is adjusted to deviate from the theoretical path direction and the angle is 90°-φ.
[0027] S3. When the distance between the vehicle and the target point is less than the convergence distance L, the second virtual point is set on the extension line of the theoretical path. The vehicle continues to move toward the second virtual point, and the distance between the vehicle and the theoretical target point is calculated at all times. When the vehicle approaches the theoretical target point, the vehicle reaches the destination and stops moving. The setting of the convergence distance L can be based on actual conditions. The convergence distance L is proportional to the vehicle's driving speed. The greater the vehicle's driving speed, the greater the convergence radius. In other preferred embodiments, when the distance between the AGV vehicle and the target is less than the convergence distance L, the convergence distance L can be reduced to l, so that l is less than L and greater than 0, so that the second virtual point is still on the theoretical route rather than its extension line. And through continuous iteration, the second virtual point eventually coincides with or approaches the target point to achieve the purpose of precise navigation.
[0028] It should be noted that the convergence distance L can be adjusted according to the size of the AGV model and the navigation accuracy. The larger L is, the smoother the virtual path is, and the smaller L is, the higher the control accuracy is. In addition, in theory, when the AGV vehicle reaches the target point, the movement is completed. However, in the actual operation process, the AGV vehicle will be infinitely close to the target point and may not completely overlap with the target point. Therefore, a distance parameter can be set. When the distance between the real-time position of the AGV vehicle and the target point is less than this distance parameter, it can be considered that the AGV vehicle has reached the target point.
[0029] To further illustrate the navigation method in this embodiment, the following calculation is performed:
[0030] like Figure 3 As shown, a coordinate system is established with the point on the straight line where the theoretical path of the AGV is located as the origin of the coordinate system. The real-time position of the AGV is point P. A perpendicular line to the straight line where the theoretical path is located is drawn through point P, and the intersection point is E0. A circle is drawn with the convergence distance L as the radius and the intersection point with the theoretical path is Q. Suppose the equation of the straight line where the theoretical path is located is:
[0031] Ax+By+C=0, (where A and B are not all 0);
[0032] Point P (x0, y0) is a point outside the straight line where the theoretical path is located. According to the distance formula from a point to a straight line, the distance d from point P to the straight line where the theoretical path is located is:
[0033]
[0034] Calculate the equation of the perpendicular line through point E0, using the point slope formula, the equation of the straight line is:
[0035]
[0036] Combining the above two equations, the coordinates of point E0 can be calculated:
[0037]
[0038] A 2 x+B 2 xB 2 x0+ABy0+AC=0;
[0039] The coordinates of the point E0(x1,y1) are:
[0040]
[0041] Therefore, the coordinates of point Q(x2,y2) can be calculated:
[0042]
[0043] Therefore, by calculating the vector from P to Q, the wheel control parameters of the AGV can be obtained.
[0044] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with this technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the scope of protection of the present invention. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is limited by the attached claims rather than the above description, and it is intended to include all changes within the meaning and scope of the equivalent elements of the claims in the present invention.
Claims
1. A method for improving laser navigation accuracy, characterized in that: The following steps are involved: S1. Take the line connecting the starting point and the target point as the theoretical path, take the current position of the vehicle as the reference point, draw a perpendicular line to the theoretical path of the vehicle, and the intersection of the perpendicular line with the theoretical path is the first virtual point; S2, setting the convergence distance L as the radius, and taking the first virtual point as the center of the circle, obtaining the intersection of the circle and the theoretical path as the second virtual point, and adjusting the vehicle to move toward the second virtual point to form a fitting path; S3. When the distance between the vehicle and the target point is less than the convergence distance L, the second virtual point is set on the extension line of the theoretical path, and the vehicle continues to move toward the second virtual point.
2. A method for improving laser navigation accuracy according to claim 1, characterized in that: The fitting path is a real-time path curve formed by multiple waypoints of the AGV vehicle moving toward the second virtual point.
3. A method for improving laser navigation accuracy according to claim 1, characterized in that: In step S2, the AGV vehicle adjusts its forward direction in real time, taking the direction vector from the location of the AGV vehicle to the second virtual point as the direction.
4. The method for improving laser navigation accuracy according to claim 1, characterized in that: The convergence distance L is proportional to the driving speed of the vehicle. The greater the driving speed of the vehicle, the greater the convergence radius.
5. The method for improving laser navigation accuracy according to claim 1, characterized in that: In step S3, the convergence distance L is reduced to l, so that l is smaller than L and greater than zero.