Route planning method and system cooperating with global planning and local obstacle avoidance

Abstract

The invention discloses a path planning method and system cooperating with global planning and local obstacle avoidance, and relates to the technical field of unmanned aerial vehicle routing inspection path planing.The method comprises the steps that when an unmanned aerial vehicle flies according to a global path, when it is detected that an obstacle exists and conflicts with a current air route, local obstacle avoidance planning is switched to be executed to bypass the obstacle; after obstacle avoidance is completed, switching back to global path following; when the deviation between the flight path and the original global path exceeds a threshold value due to local obstacle avoidance detour, triggering re-planning and updating of the global path; global planning and local obstacle avoidance of the unmanned aerial vehicle in the whole voyage are mutually coordinated and seamlessly switched, so that calculation overhead caused by frequent re-planning is avoided, and smooth transition and coherent optimization of the flight path in a dynamic environment are guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of unmanned aerial vehicle inspection path planning, and in particular to a path planning method and system for coordinated global planning and local obstacle avoidance. Background Art

[0002] With the development of drone technology, autonomous drone inspections have gained widespread application in fields such as power and oil and gas pipeline inspections. Efficient and secure path planning is a key technology. Currently, commonly used path planning algorithms are categorized into two main categories: global planning and local obstacle avoidance, each with its own advantages and disadvantages. For global path planning, the classic A algorithm, due to its simplicity and efficiency, is widely used for finding the shortest path in two-dimensional environments.

[0003] Chinese patent publication number CN119440049A discloses a method for generating drone inspection routes based on an optimized A-algorithm. This method improves upon the A-algorithm's heuristic function by simultaneously considering the distances from both the current node and the parent node to the target in the cost function. It avoids areas with dense obstacles by combining distance and obstacle density, and incorporates the Floyd algorithm for path smoothing. This solution improves path safety and smoothness in static environments.

[0004] However, after the global planning is completed, there is a lack of coordination with local obstacle avoidance, and the global path may fail when the environment changes. Summary of the Invention

[0005] In order to overcome the above-mentioned shortcomings, the present invention aims to provide a path planning method, system, corresponding drone and computer-readable storage medium that coordinate global planning and local obstacle avoidance, so as to solve the problem in the prior art that the drone lacks coordination with local obstacle avoidance after completing global planning.

[0006] To achieve the above objectives, the present invention provides the following technical solutions: a path planning method that coordinates global planning and local obstacle avoidance. When a UAV is flying along a global path and detects an obstacle that conflicts with the current route, it switches to executing local obstacle avoidance planning to circumvent the obstacle. After obstacle avoidance is completed, switch back to global path following; When the local obstacle avoidance causes the trajectory to deviate from the original global route by more than a threshold, the global path is replanned and updated.

[0007] As a further solution of the present invention: when an obstacle is detected and the obstacle conflicts with the current route, the global path following is immediately suspended and the local obstacle avoidance planning is switched to execute to bypass the obstacle.

[0008] As a further embodiment of the present invention: After switching to executing local obstacle avoidance planning, the drone relies on the potential field to guide its movement.

[0009] As a further solution of the present invention: a dynamic balancing strategy of weight factors is introduced in mode switching, using parameters The influence of global path guidance and local potential field guidance on UAV motion is weighted separately: When there are no obstacles in the environment, ,At this time, the UAV flies according to the globally planned route; When an obstacle appears and local obstacle avoidance is required, the corresponding Values ​​are set to enhance the local guidance effect and apply corresponding offsets to the heading.

[0010] As a further solution of the present invention: the determination of the completion of obstacle avoidance includes: the current nearest obstacle has left the perception range or the drone has moved outside the obstacle shadow of the global path.

[0011] As a further solution of the present invention: when the deviation between the trajectory and the original global route due to local obstacle avoidance exceeds a threshold, a replanning and updating of the global path is triggered, including: After obstacle avoidance is completed, the shortest distance from the current drone position to the global path or the distance to the next navigation point is calculated. If the distance exceeds the threshold, a new round of global path replanning is triggered.

[0012] As a further solution of the present invention: triggering a new round of global path replanning includes: using the current position of the drone as the new starting point and the original target point as the end point, running the A* algorithm under the updated map information to generate a new global optimal path, and updating the subsequent navigation point sequence accordingly.

[0013] The present invention also provides the following technical solution: a UAV path planning system, comprising a decision switching module; The decision switching module is suitable for using the above-mentioned path planning method of coordinated global planning and local obstacle avoidance to perform mode switching.

[0014] The present invention also provides the following technical solution: a patrol drone, comprising a processor and a memory arranged to store computer-executable instructions, wherein when the executable instructions are executed, the processor executes the above-mentioned path planning method of coordinated global planning and local obstacle avoidance.

[0015] The present invention also provides the following technical solution: a computer-readable storage medium, which stores one or more programs, and when the one or more programs are executed by a processor, implements the above-mentioned path planning method of coordinated global planning and local obstacle avoidance.

[0016] Compared with existing technologies, the beneficial effect of this technical solution is that the drone's global planning and local obstacle avoidance are coordinated and seamlessly switched throughout the entire flight, which not only avoids the computational overhead caused by frequent replanning, but also ensures a smooth transition and coherent optimization of the trajectory in a dynamic environment.

[0017] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 This is a schematic diagram of the main process of the path planning system of the present invention; Figure 2 It is the trigger judgment process for local dynamic obstacle avoidance; Figure 3 This is a schematic diagram of the fusion switching state of global planning and local planning; Figure 4 It is the structure diagram of the perception window and potential field guidance; Figure 5 A schematic diagram of the trajectory for avoiding obstacles in three-dimensional space; Figure 6 This is a circuit block diagram of the UAV path planning system of the present invention. DETAILED DESCRIPTION

[0020] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0021] See also Figure 1-6, a UAV path planning system 100, the overall architecture of which includes a global path planning module 110, a local obstacle avoidance planning module 120, and a decision switching module 130. The system input is the coordinates of the starting point and target point of the UAV, environmental map information, and real-time perception data (for example, for detecting dynamic obstacles) through the UAV's onboard sensors. The environmental map information may include map information such as the location of static obstacles, terrain height, flight restricted areas, strong wind areas, flight resistance, etc. The system output is a safe and feasible flight route (navigation point sequence) from the starting point to the target. The path is smooth and continuous and avoids dynamic obstacles. It can be used to guide the UAV's automatic cruising and inspection. The key components and workflow of the system of the present invention will be elaborated in detail below.

[0022] In this embodiment, in the global path planning module, at the start of a mission, if static map information of the environment is known, the present invention first uses an improved A* algorithm to perform global path planning. Global path planning is performed on an offline digital map or grid map, generating a preliminary optimal path from the starting point to the end point. Unlike the traditional A* algorithm, this invention introduces a multi-dimensional heuristic evaluation function to guide the search direction. The improved A* algorithm calculates the evaluation function at each node expansion step: in, Indicates the starting point to the current node The cumulative cost, heuristic function Indicates the current node The estimated cost to reach the destination node.

[0023] Heuristic function By distance component and energy consumption Composition, heuristic function The expression is: in, For nodes The straight-line distance to the target, is the minimum additional energy consumption estimated based on altitude change and flight resistance, 、 is the weight coefficient.

[0024] The present invention will The design is the aforementioned multi-dimensional comprehensive heuristic function to simultaneously consider factors such as distance and energy consumption to improve the rationality of global path evaluation.

[0025] For example, in flat airspace It places more emphasis on straight-line distance and increases the weight of energy consumption cost in complex terrain or strong wind areas, thereby adaptively balancing the two goals of shortest flight distance and lowest energy consumption.

[0026] When satisfied Consistency (i.e. the actual minimum cost from any node to the target is no less than ), the improved A* algorithm can still guarantee to find the global optimal solution. By adjusting the heuristic function weight, the global planning of the present invention not only ensures search efficiency, but also takes into account the economy and safety of drone flight.

[0027] In this embodiment, the output of global path planning is a navigation point sequence consisting of a series of ordered waypoints. ,in It's the starting point. is the target point, the others These navigation points are usually located in safe and open areas with few obstacles. They are the coordinate points that the drone should ideally pass through in sequence. The navigation point sequence provides a guiding skeleton for subsequent local planning: the drone will try to fly along this sequence in the direction of Past .

[0028] In some embodiments, if the environment map is unknown or incomplete, the present invention can operate in a heuristic exploration mode: Initially, global A* planning is skipped, and the system directly enters the local planning phase, gradually approaching the target through continuous perception and local search. During this process, the system gradually builds an environment map in the background, triggering global path planning as appropriate. Once a reliable global navigation point sequence is obtained, the drone can be guided according to the above process. In the following examples, it is assumed that the environment is known and the global navigation point sequence has been obtained to illustrate the system's operating logic under normal circumstances.

[0029] In this embodiment, after takeoff, the drone will fly along a path according to the sequence of navigation points provided by the global plan. During flight, the local obstacle avoidance planning module runs continuously to cope with sudden obstacles and environmental changes that may occur along the way. Local planning is based on the artificial potential field (APF) method for dynamic obstacle avoidance. The core concept is to regard the drone as a particle in motion under force. Targets in the environment generate a gravitational field on it, and obstacles generate a repulsive field. The drone adjusts its movement in the direction of the resultant force, thereby achieving obstacle avoidance and navigation. This invention has made multiple improvements to the classic APF algorithm, making it more suitable for the real-time obstacle avoidance needs of drones.

[0030] The perception system (such as lidar, camera or radar) carried by the drone scans the surrounding environment at a fixed frequency to obtain the direction, distance and movement information of obstacles in the local range at the current moment. For example, the perception range is set as a circular window centered on the drone (such as Figure 4(as shown in the figure), the radius R is determined by the effective detection range of the sensor. A local grid map, known as the potential field grid map, is then created within this sensing circle. The potential field grid map discretizes the local space into a grid with a certain resolution, with each grid recording the potential energy value at that location. During initialization, the potential energy of each grid is set to 0. Then, based on the currently detected target points and obstacles, the potential field grid map is used to calculate the superposition of attractive and repulsive forces.

[0031] Specifically, first determine the local sub-goal set within the perception window: traverse the global navigation point sequence , select the navigation points that fall within the current perception range (radius R) and record them as a set These points are the temporary goals of this round of local planning. If the set G is not empty, each sub-goal point is Calculate the gravitational potential field: for example, using the quadratic gravitational potential energy function in, Indicates the current position of the drone. For drone to sub-target distance, is the gravitational coefficient. When the UAV is located in different grids, Calculate the gravitational vector based on the relative displacement The direction of the gravitational vector points to the sub-target , its size is proportional to the distance, that is, the farther the distance, the greater the gravity. In the case of multiple sub-targets, the direction of gravity generated by each target on the drone may be different. The present invention adopts the gravity synthesis strategy: all The generated gravitational vectors are superimposed to obtain the total gravitational force on the drone. This combined gravity simultaneously points toward a "balance of forces" at multiple target points, guiding the drone in the optimal direction. As can be seen, the combined gravity actually gives closer navigation points a greater pulling effect, rather than being restricted to a single fixed sub-target. This ensures that the drone receives continuous multi-target guidance: even if a navigation point is temporarily inaccessible due to an obstacle, the combined gravity will guide the drone toward other nearby navigation points, preventing it from becoming stagnant.

[0032] Next, based on the currently perceived obstacle set Construct a repulsive potential field. For each obstacle , first calculate the distance between the drone and it To ensure safety, the obstacle is considered as a slightly expanded entity when calculating the repulsive force, that is, the effective distance is used. ( is the effective radius of the obstacle) to provide the necessary safety margin. Less than the preset repulsive influence threshold When the obstacle generates repulsive force on the drone; when it exceeds The influence is ignored. Repulsion function in, is the repulsion coefficient. When, regulations From this potential energy, we can get the repulsive force vector: The direction of Decision, point away from obstacles The direction of the obstacle increases sharply as the distance decreases. When there are multiple obstacles, The total repulsive force is obtained by summing The dynamic obstacle prediction repulsion model of the present invention further introduces obstacle motion prediction on the basis of the above: for dynamic obstacles with speed, the preview time is selected , predicting that After the position ,in is the velocity vector of the obstacle, and the distance from the drone to the predicted position Instead of static distance , which is used to calculate the repulsive force. The predicted repulsive force of the dynamic obstacle will increase earlier than that of the static situation, so that the UAV can bypass it in advance, such as Figure 2 As shown, the local obstacle avoidance decision-making process first determines whether an obstacle is ahead of the route and calculates the potential collision risk based on the predicted trajectory before deciding whether to trigger obstacle avoidance. The dynamic repulsion model effectively prevents the drone from chasing moving targets or being caught off guard by sudden obstacles, improving the proactiveness and stability of obstacle avoidance.

[0033] The gravity of all the above sub-targets and the repulsion of obstacles are superimposed to form the resultant force currently acting on the drone. At this point, the problem of local planning of the drone is transformed into choosing the next movement position along the direction of the resultant force. In the continuous space, the drone will adjust its heading in real time to make the flight direction consistent with the direction of the resultant force. In the discrete grid diagram, the direction of the fastest potential energy decrease in the adjacent grid is selected (this is equivalent to sampling along the direction of the resultant force). The potential field grid diagram provides an intuitive basis for this process: the grid potential energy value is given by and Together, the direction of the gradient descent of the potential energy around the drone's current position is the local optimal direction of travel. The drone's local obstacle avoidance planning in this invention can be understood as a rolling optimization search on a potential field grid: each cycle, the potential field distribution is updated based on the latest environment, and then a step is moved toward a location with lower potential energy. This iterative process gradually approaches the local sub-target and avoids obstacles.

[0034] In this embodiment, after determining the direction of movement based on the combined force, the system can also appropriately adjust the speed and trajectory in combination with the kinematics of the drone to achieve smooth obstacle avoidance.

[0035] First, for the heading control of the drone, the angle between the resultant force direction and the current nose direction (for example, confirmed by the gyroscope, accelerometer, magnetometer, etc. on the drone) can be used as the steering angle that needs to be corrected. ,The UAV uses a trajectory controller (such as heading angle PID or attitude solver) to gradually make the actual flight direction approach the direction of the resultant force, thus avoiding instability caused by sharp turns.

[0036] Secondly, in terms of speed control, when the distance to the obstacle ahead is close or the repulsive force is large, the flight speed should be appropriately reduced; on the contrary, when there is no obstruction, the cruising speed can be restored. This speed adjustment can be calculated linearly or nonlinearly based on the distance to the nearest obstacle: for example in, is the preset cruising speed, is the safety distance threshold. When it approaches 0, it will slow down to a hovering state. Through the above-mentioned speed-obstacle avoidance linkage control, the UAV can maintain a reasonable speed during the obstacle avoidance process, so as not to miss the turn due to excessive inertia or oscillate due to excessive avoidance.

[0037] The present invention can effectively solve the local minimum problem in the traditional artificial potential field method, and the situation where the drone is symmetrically surrounded by multiple obstacles causes the resultant force to be offset. , the drone may become stagnant or wander back and forth near a certain point. To this end, the present invention introduces a simulated annealing perturbation mechanism in local planning: when it is detected that the drone has failed to significantly approach the sub-target after multiple iterations or the speed has dropped to near zero, the simulated annealing algorithm is triggered to apply a random perturbation displacement or additional virtual force to the current position of the drone, causing it to temporarily deviate from its original equilibrium position. This disturbance has a large initial amplitude, guiding the drone out of the local trap, and then gradually reduces the disturbance amplitude to ensure that the movement tends to be stable. The simulated annealing mechanism has a certain degree of random exploration, which can effectively help the drone escape from the local minimum point and move in the right direction again. Combined with the above-mentioned multi-target gravitational mechanism and dynamic repulsion model, the local obstacle avoidance algorithm of the present invention can maintain reliable obstacle avoidance performance in most complex scenarios.

[0038] In this embodiment, the path planning system of the present invention realizes the organic integration of global planning and local planning through the decision switching module.

[0039] During the entire process of the UAV's mission, the system intelligently switches between the "driving along the global path" and "local obstacle avoidance and detour" modes based on real-time environmental analysis (e.g. Figure 3 Initially, the drone follows the global navigation point sequence. When the local obstacle avoidance module detects an obstacle ahead that may conflict with the current route (refer to Figure 2 ), the system immediately suspends strict global path following and instead executes local obstacle avoidance planning (APF algorithm) to circumvent the obstacle. Obstacle avoidance mode persists throughout the drone's circumvention of the obstacle: during this period, the drone relies primarily on the aforementioned potential field for guidance, with the original global target point retained only as a remote reference. Obstacle avoidance is determined to be complete based on the following conditions: the nearest obstacle has left the perception range or the drone has moved outside the obstacle's shadow on the global path (i.e., returning to an unobstructed area of ​​the originally planned path). Once obstacle avoidance is complete, the system switches back to global path following mode, guiding the drone toward the next global navigation point.

[0040] It's important to emphasize that by the time local obstacle avoidance concludes, the drone is often no longer on the precise trajectory of the originally planned path. If the deviation is small, no additional processing is required; the drone will fly directly toward the navigation point, gradually converging back to the global route. However, if the deviation is too large, the remaining path may become suboptimal or unconnected. To this end, the present invention incorporates a path deviation monitoring mechanism: it calculates the shortest distance from the current drone's position to the global path or the distance to the next navigation point. If this threshold is exceeded, the global path validity is considered to have decreased, triggering a new round of global path replanning. At this point, using the drone's current position as the new starting point and the original target point as the end point, an improved A* algorithm is run based on updated map information to generate a new globally optimal path (bypassing previously inaccessible areas), and the subsequent navigation point sequence is updated accordingly. The results of the global replanning replace the original navigation points that have not yet been reached, ensuring that the plan remains synchronized with environmental changes. If replanning is not triggered, the drone continues to travel along the original navigation point sequence.

[0041] In order to maintain a smooth transition of the trajectory during the mode switching process, the present invention introduces a dynamic balancing strategy of weight factors in the decision switching module. The influence of global path guidance and local potential field guidance on UAV motion is weighted separately: when there is no obstacle interference in the environment, At this time, the UAV strictly follows the globally planned route to fly; when an obstacle appears and needs to be avoided locally, the speed is appropriately reduced. The value is used to enhance the local guidance effect of APF and apply a moderate offset to the heading. The value is selected to achieve a dynamic balance and seamless connection between global planning and local obstacle avoidance guidance. This ensures that the drone flies along the optimal global route under normal circumstances, and can smoothly deviate from the original route to avoid obstacles when circumventing local obstacles. After the obstacle avoidance is completed, it can naturally transition back to the global route, avoiding sudden changes in the track during the switching process, reducing the computational overhead caused by frequent replanning, and ensuring the consistency and safety of the route in dynamic environments.

[0042] In this embodiment, the global / local switching process is repeated and continued until the UAV finally reaches the target point. Figure 1As shown, the main process of the planning system of the present invention can be summarized as follows: initialization → global planning → loop: obstacle detection → local obstacle avoidance → path restoration → end of target detection. This architecture enhances global planning through event-driven local planning: the local planning module is enabled only when obstacle avoidance is required, which greatly reduces unnecessary computing overhead; after obstacle avoidance is completed, it immediately returns to the global path following to ensure the overall optimization of the route. With the help of multi-target guidance and path fusion strategies, the global and local planning modes are naturally connected during the transition, and no obvious path segmentation or oscillation occurs. For example, under the fusion strategy of the present invention, even if the drone frequently enters and exits the obstacle avoidance mode, its motion trajectory remains smooth and coherent, which is more in line with human driving intuition. Figure 3 Shown is a state transition diagram of the global-local planning fusion of the present invention.

[0043] In this embodiment, in fact, a path planning method that coordinates global planning and local obstacle avoidance is also proposed, that is, the method of intelligently switching between the two modes of "driving along the global path" and "local obstacle avoidance and detour" mentioned above.

[0044] In this embodiment, in fact, a patrol drone is also proposed, including a processor and a memory arranged to store computer-executable instructions. When the executable instructions are executed, the processor executes the above-mentioned path planning method of coordinated global planning and local obstacle avoidance.

[0045] In this embodiment, in fact, a computer-readable storage medium is also proposed, which stores one or more programs. When the one or more programs are executed by a processor, they implement the above-mentioned path planning method of collaborative global planning and local obstacle avoidance.

[0046] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be included therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

Claims

1. A path planning method that coordinates global planning and local obstacle avoidance, characterized in that: When the drone is flying along the global path and an obstacle is detected and conflicts with the current route, it switches to executing local obstacle avoidance planning to bypass the obstacle. After obstacle avoidance is completed, switch back to global path following; When the local obstacle avoidance causes the trajectory to deviate from the original global route by more than a threshold, the global path is replanned and updated.

2. The path planning method for coordinated global planning and local obstacle avoidance according to claim 1, characterized in that: When an obstacle is detected and conflicts with the current route, the global path following is immediately suspended and local obstacle avoidance planning is performed to bypass the obstacle.

3. The path planning method for coordinated global planning and local obstacle avoidance according to claim 1, characterized in that: After switching to executing local obstacle avoidance planning, the drone relies on the potential field to guide its movement.

4. The path planning method for coordinated global planning and local obstacle avoidance according to claim 3, characterized in that: Introducing a dynamic balancing strategy of weight factors in mode switching, using parameters The influence of global path guidance and local potential field guidance on UAV motion is weighted separately: When there are no obstacles in the environment, ,At this time, the UAV flies according to the globally planned route; When an obstacle appears and local obstacle avoidance is required, the corresponding Values ​​are set to enhance the local guidance effect and apply corresponding offsets to the heading.

5. The path planning method for coordinated global planning and local obstacle avoidance according to claim 1, characterized in that: Obstacle avoidance is completed when the nearest obstacle is out of the sensing range or the drone moves outside the obstacle shadow of the global path.

6. The path planning method for coordinated global planning and local obstacle avoidance according to any one of claims 1 to 5, characterized in that: When the local obstacle avoidance detour causes the trajectory to deviate from the original global route by more than a threshold, the global path is replanned and updated, including: After obstacle avoidance is completed, the shortest distance from the current drone position to the global path or the distance to the next navigation point is calculated. If the distance exceeds the threshold, a new round of global path replanning is triggered.

7. The path planning method for coordinated global planning and local obstacle avoidance according to claim 6, characterized in that: Triggering a new round of global path replanning includes: using the current position of the drone as the new starting point and the original target point as the end point, running the A* algorithm under the updated map information to generate a new global optimal path, and updating the subsequent navigation point sequence accordingly.

8. A UAV path planning system, characterized in that: Including decision switching module; The decision switching module is suitable for performing mode switching by adopting a path planning method for coordinated global planning and local obstacle avoidance as described in any one of claims 1-7.

9. A patrol drone, characterized in that: The invention comprises a processor and a memory arranged to store computer-executable instructions, wherein when the executable instructions are executed, the processor executes a path planning method for coordinated global planning and local obstacle avoidance as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that The computer-readable storage medium stores one or more programs, which, when executed by a processor, implement the path planning method for coordinated global planning and local obstacle avoidance as described in any one of claims 1 to 7.

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