An autonomous landing device and method based on an amphibious platform

Abstract

The present invention discloses an autonomous landing device and method based on an amphibious platform, which relates to the field of automatic control technology. The device comprises: a sensor component for acquiring data information of the autonomous landing of the amphibious platform; a support component arranged above the roof of the amphibious platform for adjusting the posture of the sensor component; a control component arranged inside the amphibious platform, connected to the support component and the sensor component respectively, for generating motion control instructions according to the data information acquired by the sensor component, and sending the motion control instructions to the control system of the amphibious platform, and the control system controls the autonomous landing of the amphibious platform according to the motion control instructions. The present invention can realize rapid and safe landing in the case of unknown underwater shore terrain.

Description

Technical Field

[0001] The present invention relates to the field of automatic control technology, and in particular to an autonomous landing device and method based on an amphibious platform. Background Art

[0002] An amphibious unmanned platform is a special vehicle composed of a land walking system and a water propulsion system. Its important feature is that it can travel across water and land. It is usually used in rescue, entertainment, military and other fields. However, at the junction of water and land, there is a fusion of different media such as water, hard soil, and soft soil. In addition to the complex and variable terrain in this area, the water quality is also relatively turbid, making it difficult to accurately detect the underwater shore terrain, all of which have caused difficulties for the landing of the amphibious platform.

[0003] At present, there are two main landing methods, one of which is: manual remote control landing. Most of the existing amphibious platforms are manned platforms and remote control unmanned platforms. Their landing plan is carried out manually, relying on human perception, experience and control to determine where to land and how to land. The disadvantages of this landing plan are: 1. There are large delays and uncertainties in human perception, experience and control, and the efficiency of landing is low; 2. When communication is limited, the manual remote control method cannot be carried out; 3. The cost of training remote control personnel is high. Another landing plan is: direct beaching. This plan often requires manual prediction of the landing site, but the direct beaching method is used in control. The amphibious platform does not consider the underwater shore situation and has more stringent requirements on the terrain. The disadvantages of this landing plan are: 1. Manual prediction or even pre-test exploration of the terrain is required. Although the beaching speed is high, the efficiency of the early prediction is low, making the entire process inefficient; 2. The uncertainty of manual prediction is large, and direct beaching may cause siltation or even damage to the fuselage. There is an urgent need for an autonomous landing plan for amphibious platforms suitable for situations where the underwater shore terrain is unknown. Summary of the invention

[0004] The purpose of the present invention is to provide an autonomous landing device and method based on an amphibious platform, which can achieve rapid and safe landing when the underwater beach terrain is unknown.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] An autonomous landing device based on an amphibious platform, the device comprising:

[0007] Sensor components, used to obtain data information for autonomous landing of amphibious platforms;

[0008] a support assembly, disposed above the roof of the amphibious platform, for adjusting the posture of the sensor assembly;

[0009] A control component is arranged inside the amphibious platform and is connected to the support component and the sensor component respectively. It is used to generate motion control instructions according to data information obtained by the sensor component and send the motion control instructions to the control system of the amphibious platform. The control system controls the amphibious platform to land autonomously according to the motion control instructions.

[0010] Optionally, the sensor assembly includes a navigation radar, a camera, a laser radar, a combined navigator, a water immersion sensor and a contact switch; the water immersion sensor and the contact switch are both arranged at the bottom of the amphibious platform; the navigation radar, the camera and the laser radar are all arranged on the support assembly;

[0011] The navigation radar is used to obtain the beach contour for the autonomous landing of the amphibious platform;

[0012] The camera is used to obtain beach images of the amphibious platform autonomously landing;

[0013] The laser radar is used to detect the geometric features of the beach for the autonomous landing of the amphibious platform;

[0014] The integrated navigator is used to obtain the position and posture data of the amphibious platform for autonomous landing;

[0015] The immersion sensor is used to obtain the positional relationship between the bottom of the amphibious platform and the water surface; the positional relationship with the water surface includes being out of the water surface and not out of the water surface;

[0016] The contact switch is used to obtain the positional relationship between the bottom of the amphibious platform and the ground; the positional relationship between the bottom of the amphibious platform and the ground includes touching the ground and not touching the ground.

[0017] Optionally, the control component includes:

[0018] A central gateway, connected to the sensor assembly, for transmitting data information collected by the sensor assembly;

[0019] An industrial computer is connected to the central gateway and is used to generate motion control instructions according to the data information and send the motion control instructions to the control system of the amphibious platform.

[0020] Optionally, the support assembly includes a lifting rod and an adjustable support; the lifting rod is vertically fixed above the roof of the amphibious platform; the adjustable support is vertically fixed on the lifting rod; the navigation radar is arranged on the lifting rod; the camera and the laser radar are both arranged on the adjustable support.

[0021] An autonomous landing method based on an amphibious platform, the method is applied to the above-mentioned device, the method comprising:

[0022] Setting a target location and setting a first distance threshold and a second distance threshold;

[0023] Determine the distance between the position of the amphibious platform and the intersection point of the initial beach contour obtained from the electronic nautical chart; the intersection point of the initial beach contour is the point where the straight line where the position of the amphibious platform and the target position are located intersects the initial beach contour;

[0024] When the distance is greater than the first distance threshold, obtaining obstacle information in the electronic nautical chart according to the shore contour data output by the navigation radar;

[0025] Generate a first driving path according to the obstacle information and the target position, and update the distance;

[0026] When the distance is less than or equal to the first distance threshold and greater than the second distance threshold, determining the beach type according to the beach image output by the camera;

[0027] According to the geometric features of the beach output by the laser radar, an elevation map is established to determine the beach topography;

[0028] Generate a second driving path according to the beach type and the beach terrain, and update the distance;

[0029] When the distance is less than or equal to the second distance threshold, the successful landing target position is determined based on the position relationship between the bottom of the amphibious platform and the ground output by the contact switch and the position relationship between the bottom of the amphibious platform and the water surface output by the immersion sensor.

[0030] Optionally, generating a first driving path according to the obstacle information and the target position, and updating the distance specifically includes:

[0031] Obtaining a two-dimensional occupancy grid map according to the obstacle information and the target position;

[0032] According to the two-dimensional occupancy grid map, an A* algorithm is used to obtain a path planning result; the path planning result includes a successful planning and an unsuccessful planning;

[0033] When the path planning result is that the planning is unsuccessful, the amphibious platform travels a first set distance along the beach contour and updates the obstacle information;

[0034] When the path planning result is successful, the first driving path is obtained and the distance is updated.

[0035] Optionally, when the distance is less than or equal to the first distance threshold and greater than the second distance threshold, determining the beach type according to the beach image output by the camera specifically includes:

[0036] When the distance is less than or equal to the first distance threshold and greater than the second distance threshold, acquiring data collected by the camera;

[0037] According to the data collected by the camera, the target detection yolov5 algorithm is applied to identify the beach type; the beach types include hard beaches, soft beaches and reef beaches.

[0038] Optionally, the step of establishing an elevation map and determining the beach topography based on the beach geometric features output by the laser radar specifically includes:

[0039] Obtain the geometric characteristics of the beach output by the laser radar;

[0040] According to the geometric features of the beach, an elevation map is established for the beach topography to obtain the beach topography above water;

[0041] According to the elevation map, the underwater shore topography is fitted in the form of a quadratic parabola using the least squares method to obtain the underwater shore topography;

[0042] The beach topography is determined based on the above-water beach topography and the underwater beach topography.

[0043] Optionally, generating a second driving path according to the beach type and the beach terrain, and updating the distance specifically includes:

[0044] Eliminate the data of the beach type being a reef beach from the data collected by the camera, and obtain passable beach type data;

[0045] According to the passable beach type data, the beach terrain is screened to obtain a passable beach terrain;

[0046] According to the passable beach terrain, an A* algorithm is used to obtain a path planning result; the path planning result includes a successful planning and an unsuccessful planning;

[0047] When the path planning result is that the planning is unsuccessful, the amphibious platform travels a second set distance along the beach contour and updates the beach type;

[0048] When the path planning result is successful, the second driving path is obtained and the distance is updated.

[0049] Optionally, when the distance is less than or equal to the second distance threshold, determining the successful landing target position according to the position relationship between the bottom of the amphibious platform and the ground output by the contact switch and the position relationship between the bottom of the amphibious platform and the water surface output by the immersion sensor specifically includes:

[0050] When the distance is less than or equal to the second distance threshold, obtaining the positional relationship between the bottom of the amphibious platform and the ground output by the contact switch; the positional relationship between the bottom of the amphibious platform and the ground includes touching the ground and not touching the ground;

[0051] When the position relationship between the bottom of the amphibious platform and the ground is touching the ground, the amphibious platform travels along the second driving path for a set time, and obtains the position and posture data of the amphibious platform output by the integrated navigation system;

[0052] According to the posture data, determining whether the position of the amphibious platform is elevated;

[0053] If the position of the amphibious platform rises, the position relationship between the bottom of the amphibious platform and the water surface output by the immersion sensor is obtained; the position relationship between the bottom of the amphibious platform and the water surface includes being out of water and not out of water; when the position relationship between the bottom of the amphibious platform and the water surface is out of water, the target position for successful landing is determined.

[0054] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0055] The autonomous landing device based on an amphibious platform provided by the present invention includes: a sensor component for acquiring data information of the autonomous landing of the amphibious platform; a support component, arranged above the roof of the amphibious platform, for adjusting the posture of the sensor component; a control component, arranged inside the amphibious platform, connected to the support component and the sensor component respectively, for generating motion control instructions according to the data information acquired by the sensor component, and sending the motion control instructions to the control system of the amphibious platform, and the control system controls the autonomous landing of the amphibious platform according to the motion control instructions. The present invention updates the driving path of the amphibious platform in real time through the data collected in real time by the sensor component, generates motion control instructions according to the driving path, and sends the motion control instructions to the control system of the amphibious platform, so that the amphibious platform can autonomously land according to the motion control instructions. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. 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 creative labor.

[0057] Figure 1 A schematic diagram of an autonomous landing device based on an amphibious platform provided by the present invention;

[0058] Figure 2 A flow chart of the autonomous landing method based on an amphibious platform provided by the present invention;

[0059] Figure 3 A schematic diagram of the autonomous landing area division based on the amphibious platform provided by the present invention;

[0060] Figure 4 A schematic diagram of the far shore area provided by the present invention;

[0061] Figure 5 A schematic diagram of the landing strategy for the far-shore area provided by the present invention;

[0062] Figure 6 A schematic diagram of unknown underwater beach topography in the nearshore area provided by the present invention;

[0063] Figure 7 A schematic diagram of the estimated underwater beach topography in the nearshore area provided by the present invention;

[0064] Figure 8 A schematic diagram of the landing strategy for the nearshore area provided by the present invention;

[0065] Fig. 9 A schematic diagram of contact determination in the berthing area provided by the present invention;

[0066] Fig.10 A schematic diagram of a trigger switch for the docking area provided by the present invention;

[0067] Fig.11 A schematic diagram of the landing strategy for the berthing area provided by the present invention;

[0068] Fig.12 A schematic diagram of the landing area provided by the present invention;

[0069] Fig.13 A schematic diagram of the landing strategy for the landing area provided by the present invention;

[0070] Fig.14 This is a schematic diagram of the state machine design of the autonomous landing system based on the amphibious platform provided by the present invention.

[0071] Explanation of symbols:

[0072] Antenna—1, water propulsion system—2, immersion sensor—3, land travel system—4, navigation radar—5, camera—6, lidar—7, adjustable support—8, lifting rod—9, combined navigator—10, contact switch—11, central gateway—12, industrial computer—13, vehicle controller—14. DETAILED DESCRIPTION

[0073] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 creative work are within the scope of protection of the present invention.

[0074] The purpose of the present invention is to provide an autonomous landing device and method based on an amphibious platform, which can achieve rapid and safe landing when the underwater beach terrain is unknown.

[0075] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0076] The present invention proposes an autonomous landing method and device for amphibious unmanned platforms, which are particularly applicable to situations where the underwater shore terrain is unknown. The solution includes hardware system deployment, landing strategies under different situations, and landing system state machine design. The present invention aims to solve the problem of autonomous landing of unmanned amphibious platforms. The unmanned amphibious platform consists of a land walking system 4 and an aquatic propulsion system 2, and there are many mature solutions for driving on land and water. However, the environment at the junction of land and water is complex, and the underwater shore terrain is difficult to detect, and the autonomous landing technology of amphibious platforms is still blank.

[0077] The amphibious platform chassis includes a fuselage, a water propulsion system 2, a land walking system 4, a vehicle controller 14, an antenna 1 and other chassis-related parts. The specific form of the amphibious platform can be an amphibious vehicle or an amphibious robot. The specific form of the water propulsion system 2 can be a propeller type, a jet pump type, or a paddle type. The specific form of the land walking system 4 can be a flat crawler type, a triangular crawler type, a wheel type, or a leg-foot type. Among them, the vehicle controller 14 is a control component in the control system of the amphibious platform.

[0078] like Figure 1 As shown, the present invention provides an autonomous landing device based on an amphibious platform, the device comprising:

[0079] The sensor assembly includes a navigation radar 5, a camera 6, a laser radar 7, an integrated navigator 10, a water sensor 3 and a contact switch 11, which are used to obtain data information of the autonomous landing of the amphibious platform; the integrated navigator 10 is fixedly installed inside the fuselage of the amphibious platform. The water sensor 3 and the contact switch 11 are both arranged at the bottom of the amphibious platform; further, the water sensor 3 is installed at the rear of the fuselage of the amphibious platform chassis. The contact switch 11 is installed at the front of the fuselage of the amphibious platform chassis. In order to ensure the reliability of contact judgment, multiple contact switches 11 are installed at the same time.

[0080] A support assembly is arranged above the roof of the amphibious platform and is used to adjust the posture of the sensor assembly; the navigation radar 5, the camera 6 and the laser radar 7 are all arranged on the support assembly.

[0081] The control component is arranged inside the amphibious platform, and is connected to the support component and the sensor component respectively, and is used to generate motion control instructions according to the data information obtained by the sensor component, and send the motion control instructions to the control system of the amphibious platform, and the control system controls the amphibious platform to land autonomously according to the motion control instructions. Specifically, the industrial computer 13 generates motion control instructions based on the information provided by the sensor data, and sends them to the vehicle controller 14. The vehicle controller 14 converts the upper-level control instructions into the lower-level control instructions, and sends them to the water propulsion system 2 and the land walking system 4. The water propulsion system 2 and the land walking system 4 execute the instructions and feedback the status.

[0082] Specifically, the navigation radar 5 in the sensor component is used to obtain the beach contour of the amphibious platform for autonomous landing; the camera 6 is used to obtain the beach image of the amphibious platform for autonomous landing; the laser radar 7 is used to detect the geometric characteristics of the beach for autonomous landing of the amphibious platform; the combined navigator 10 is used to obtain the posture data of the amphibious platform for autonomous landing; the immersion sensor 3 is used to obtain the position relationship between the bottom of the amphibious platform and the water surface; the position relationship with the water surface includes being out of the water surface and not out of the water surface; the contact switch 11 is used to obtain the position relationship between the bottom of the amphibious platform and the ground; the position relationship with the ground includes touching the ground and not touching the ground.

[0083] Wherein, the control component comprises:

[0084] The central gateway 12 is connected to the sensor component and is used to transmit the data information collected by the sensor component.

[0085] The industrial computer 13 is connected to the central gateway 12, and is used to generate motion control instructions according to the original sensor data and send the motion control instructions to the control system of the amphibious platform.

[0086] In addition, the support assembly includes a lifting rod 9 and an adjustable support 8; the lifting rod 9 is vertically fixed above the roof of the amphibious platform; the adjustable support 8 is vertically fixed on the lifting rod 9; the navigation radar 5 is arranged on the lifting rod 9; the camera 6 and the laser radar 7 are both arranged on the adjustable support 8; and the camera 6 and the laser radar 7 are fixedly connected and installed together on the moving part of the adjustable support 8. Further, the lifting rod 9 is installed on the upper plane of the fuselage of the amphibious platform chassis, and the adjustable support 8 is installed on the moving part of the lifting rod 9. The lifting rod 9 can execute up and down movement instructions, and the adjustable support 8 can execute pitch and rotation movement instructions, and both are driven in electric form. This design allows users to adjust the posture of the sensor on the bracket according to their needs.

[0087] like Figure 2 As shown, based on the above autonomous landing device, the present invention provides an autonomous landing method based on an amphibious platform, the method comprising:

[0088] Step S1: Set the target location and set the first distance threshold and the second distance threshold.

[0089] Step S2: determine the distance between the position of the amphibious platform and the intersection of the initial beach contour obtained from the electronic nautical chart; the intersection of the initial beach contour is the point where the straight line where the position of the amphibious platform and the target position are located intersects with the initial beach contour; specifically, determine the landing area based on the distance, the first distance threshold, the second distance threshold, and the data detected by the contact switch and the immersion sensor; the landing area includes the far shore area, the near shore area, the shore area and the landing area; Figure 3 shown.

[0090] S2 specifically includes:

[0091] Step S21: Set the target position and set the distance thresholds d1 and d2.

[0092] Step S22: determining the intersection of the line connecting the position of the amphibious platform and the target position with the initial beach contour. The initial beach contour is read from the electronic nautical chart.

[0093] Step S23: Determine the distance between the position of the amphibious platform and the intersection point.

[0094] Step S24: When the distance is greater than d2, it is determined that the amphibious platform is in a far-shore area.

[0095] When the distance is less than or equal to d2 and greater than d1, it is determined that the amphibious platform is in the nearshore area.

[0096] When the distance is less than or equal to d1, and the land walking system and the contact switch are not in contact with the ground, it is determined that the amphibious platform is in the docking area.

[0097] When the distance is less than or equal to d1, and one of the land walking system or contact switch touches the ground, and the immersion sensor is in the water, it is determined that the amphibious platform is in the landing area.

[0098] Step S3: When the distance is greater than the first distance threshold, the obstacle information in the electronic nautical chart is obtained according to the shore contour data output by the navigation radar.

[0099] Step S4: Generate a first driving path according to the obstacle information and the target position, and update the distance.

[0100] S4 specifically includes:

[0101] Step S41: obtaining a two-dimensional occupancy grid map according to the obstacle information and the target position.

[0102] Step S42: According to the two-dimensional occupancy grid map, an A* algorithm is used to obtain a path planning result, wherein the path planning result includes a successful planning and an unsuccessful planning.

[0103] Step S43: When the path planning result is that the planning is unsuccessful, the amphibious platform travels a first set distance along the beach contour and updates the obstacle information.

[0104] Step S44: When the path planning result is successful, the first driving path is obtained and the distance is updated.

[0105] Step S5: When the distance is less than or equal to the first distance threshold and greater than the second distance threshold, the beach type is determined according to the beach image output by the camera.

[0106] S5 specifically includes:

[0107] Step S51: when the distance is less than or equal to the first distance threshold and greater than the second distance threshold, acquiring data collected by the camera.

[0108] Step S52: According to the data collected by the camera, the target detection yolov5 algorithm is applied to identify the beach type; the beach types include hard beaches, soft beaches and reef beaches.

[0109] Step S6: Create an elevation map based on the geometric features of the beach output by the laser radar to determine the beach topography.

[0110] S6 specifically includes:

[0111] Step S61: Obtain the beach geometric features output by the laser radar.

[0112] Step S62: according to the geometric features of the beach, an elevation map is established for the beach topography above water to obtain the beach topography above water.

[0113] Step S63: According to the elevation map, the underwater shore topography is fitted in the form of a quadratic parabola using the least squares method to obtain the underwater shore topography.

[0114] Step S64: Determine the shore topography according to the above-water shore topography and the underwater shore topography.

[0115] Step S7: Generate a second driving path according to the beach type and the beach terrain, and update the distance.

[0116] S7 specifically includes:

[0117] Step S71: Eliminate the data of the beach type being a reef beach from the data collected by the camera, and obtain passable beach type data.

[0118] Step S72: screening the beach terrain according to the passable beach type data to obtain the passable beach terrain.

[0119] Step S73: According to the passable beach terrain, an A* algorithm is used to obtain a path planning result; the path planning result includes successful planning and unsuccessful planning.

[0120] Step S74: When the path planning result is that the planning is unsuccessful, the amphibious platform travels a second set distance along the beach contour and updates the beach type.

[0121] Step S75: When the path planning result is successful, a second driving path is obtained and the distance is updated.

[0122] Step S8: When the distance is less than or equal to the second distance threshold, the successful landing target position is determined based on the positional relationship between the bottom of the amphibious platform and the ground output by the contact switch and the positional relationship between the bottom of the amphibious platform and the water surface output by the immersion sensor.

[0123] S8 specifically includes:

[0124] Step S81: when the distance is less than or equal to the second distance threshold, obtaining the positional relationship between the bottom of the amphibious platform and the ground output by the contact switch; the positional relationship between the bottom of the amphibious platform and the ground includes touching the ground and not touching the ground.

[0125] Step S82: When the positional relationship between the bottom of the amphibious platform and the ground is touching the ground, the amphibious platform travels along the second driving path for a set time, and obtains the position and posture data of the amphibious platform output by the integrated navigation system.

[0126] Step S83: Determine whether the position of the amphibious platform is elevated according to the posture data.

[0127] Step S84: If the position of the amphibious platform rises, the position relationship between the bottom of the amphibious platform and the water surface output by the immersion sensor is obtained; the position relationship between the bottom of the amphibious platform and the water surface includes being out of the water surface and not out of the water surface; when the position relationship between the bottom of the amphibious platform and the water surface is out of the water surface, the target landing position is determined to be successfully landed.

[0128] As a specific implementation of this embodiment, the principle of the autonomous landing method based on an amphibious platform provided by the present invention is as follows:

[0129] When an amphibious platform is located in a far-shore area, such as Figure 4 As shown in the figure, during the landing process, when the amphibious platform is far from the shore, it is considered to be in the far shore area, and the underwater terrain of the shore is unknown. Specifically, the first distance threshold is 200 meters, and the navigation radar with poor accuracy but long perception range is mainly used for detection to depict the shore contour. This provides a basis for the landing strategy in the far shore area.

[0130] like Figure 5 As shown, when the landing strategy in the far-shore area is started, the target position is read first. If the task is interrupted or the current positioning is not in the far-shore area, the process is terminated. Otherwise, the next step is to read the shore contour data output by the navigation radar, read the obstacles and obstacle area information marked in the electronic nautical chart, and combine the geometric information such as the target position given by the user to form a two-dimensional occupancy grid map, and use the A* algorithm to roughly generate the driving path. If the planning is successful, follow the path and enter the loop. If the planning fails, and the number of failures is less than or equal to the set number of planning times; specifically, the number of planning times is set to 5 times, then drive the first set distance to the right along the shore contour and re-enter the program loop; specifically, the first set distance is 500m. If the number of failures is too large, the process is terminated after reporting an error. This strategy can realize the exploration of landing sites along the coast of the far-shore area.

[0131] When an amphibious platform is located in a near-shore area, such as Figure 6 and Figure 7 As shown in the figure, the second distance threshold is 10 meters. When the amphibious platform reaches the sensing range of the camera and the lidar, it is considered that the amphibious platform is in the nearshore area. At this time, the camera is mainly used to identify the shore type, and the lidar is used to construct the shore terrain, thereby providing a basis for the landing strategy in the nearshore area.

[0132] like Figure 8As shown in the figure, when the landing strategy in the far-shore area is started, the target position is read first. If the task is interrupted or the current positioning is not in the near-shore area, the process is terminated. Otherwise, the next step is to initialize the counter counter to 0. Using the camera data, the target detection yolov5 algorithm is used to identify the type of beach, and the types and locations of multiple beaches can be obtained. Here, the beach types can be divided into three categories for identification, namely hard beach, soft beach, and reef beach. Among them, the hard beach has the greatest passability, followed by the soft beach, and the reef beach is considered to be impassable. The data corresponding to the reef beach type is eliminated, and the remaining data is sorted. The data corresponding to the hard beach type is ranked first, followed by the data corresponding to the soft beach type. The data corresponding to the same type of beach is sorted based on the distance to the amphibious platform, and the closer the distance, the closer it is. After sorting, a landing point list L can be formed. Each data item L[i] in the list L represents a landing point location. If the list L is an empty list, the amphibious platform is allowed to drive the first set distance to the right along the direction of the shore contour; specifically, the first set distance is 50m, and the value of the counter counter is increased by 1. If the counter value does not exceed 5, it continues to return to the shore type target detection step. If the counter value exceeds 5, the process ends. The above method can continue to explore along the shore when the landing point cannot be found. If the list L is not empty, it is traversed. During the traversal process, the laser radar is used to establish the elevation map of the shore near the landing point position in the list L in turn. Since the underwater shore terrain cannot be directly obtained by the laser radar, the least squares method is adopted here, and the underwater shore terrain is fitted in the form of a quadratic parabola using the three-dimensional point cloud data of the shore that has been obtained on the water. The shore terrain above and below the water can be merged into a complete shore terrain. Under this terrain, the A* algorithm is used for path planning. If the planning is successful, follow the changed path and enter the large loop to update the path in real time. If the planning is unsuccessful, the next landing point in the list L is planned with the above scheme. If all the landing points in list L are not successfully planned, the system returns to the first set distance along the right shore contour and returns to the camera target detection loop. This strategy allows the amphibious platform to explore and approach the landing points along the coast in the nearshore area.

[0133] When the amphibious platform is in the landing area, Fig. 9 and Fig.10 As shown in the figure, at this time, the land walking system has not touched the ground, and the contact switch has not been triggered, so it is considered that the amphibious platform is in the docking area. The ground contact status of the land walking system can be judged by an external pressure sensor or by using the internal drive motor current, hydraulic cylinder oil pressure, etc.

[0134] like Fig.11As shown, when the landing strategy in the docking area is started, the target position is read first. If the mission is interrupted or the current positioning is not in the docking area, the process is terminated, otherwise the next step is performed. When in the docking area, the navigation radar, lidar, and camera blind spots will be entered. At this time, it is necessary to follow the path before entering the docking area. Appropriately reduce the speed and follow the path to approach the target point until the mission is interrupted or the positioning is not in the docking area; when the amphibious platform is in the docking area, slow down to approach the target position.

[0135] When an amphibious platform is in a landing area, Fig.12 As shown in the figure, during the landing process, when the land walking system of the amphibious platform has contacted the beach or the contact switch is triggered, and the submerged sensor is in the water, the amphibious platform is considered to be in the landing area. At this time, the beach part has entered the blind spot of the navigation radar, laser radar, and camera, and it is necessary to rely on the contact switch, the land walking system touchdown judgment, and the submerged sensor to provide a basis for the landing strategy.

[0136] like Fig.13 As shown, when the landing strategy in the landing area is started, the target position is read first. If the task is interrupted or the current positioning is not in the landing area, the process is terminated, otherwise the next step is to determine whether the contact switch is triggered. Once triggered, it is considered that the place is not passable and the process is terminated. If the contact switch is not triggered, it is determined whether the land walking system touches the ground. If not, it means that it is no longer in the landing area and the process is terminated. If it touches the ground, it follows the path before entering the landing area to approach the target point and continues to run for a set time; specifically, the set time is 2s, and then it is determined whether the position of the amphibious platform has risen. If not, it is considered that the place is not passable and the process is terminated. If it has risen, it continues to determine whether the immersion sensor has left the water surface. If not, it continues to enter the loop. If it has left the water surface, it means that the landing is successful, and the status of successful landing is fed back, and then the process is terminated.

[0137] As a specific implementation of this embodiment, the landing strategies under various circumstances can form a state machine of the landing system, which implements a series of strategies from the far shore area to the near shore area, the docking area, the landing area, and then to a successful landing. The system status is divided into standby, far shore, near shore, docking, landing, landing, return and abnormal. When the upper layer command requires switching to the landing mode (that is, letting the landing system start working), it enters the standby state. Fig.14 As shown, the specific working process of the autonomous landing device based on the amphibious platform provided by the present invention is as follows:

[0138] When entering the standby state, first perform self-check and initialization. If a system fault is detected, jump to the abnormal state. Under normal circumstances, wait for instructions. If there is a landing instruction, leave the standby state. Confirm the state to jump to when leaving. When the current position is in the far shore area, jump to the far shore state; when the current position is in the near shore area, jump to the near shore state; when the current position is in the shore area, jump to the shore state; when the current position is in the landing area, jump to the landing state; when the current position is already on the shore, jump to the landing state. If there is a return command, jump to the return state.

[0139] When entering the far shore state, you should first drive to the far shore area. If you are already in the far shore area, proceed to the next step, that is, use the plan in the landing strategy under the far shore area to explore the shore contour along the coast and find a landing place. If you can find a landing place, plan a path and drive to it, and jump to the near shore state when you reach the near shore area. If you can't find it, jump to the abnormal state. If you receive a mission interruption signal, jump to the standby state.

[0140] When entering the nearshore state, you should first drive to the nearshore area. If you are already in the nearshore area, proceed to the next step, that is, use the above-mentioned landing strategy under the nearshore area (based on the beach type) and the landing strategy under the nearshore area (based on the beach terrain) to detect the beach type and estimate the beach shape along the coast. If you can find the landing site, plan the action and approach the beach. When you reach the docking area, jump to the docking state. If you can't find it, jump to the far shore state. If you receive a mission interruption signal, jump to the standby state.

[0141] When entering the docking state, you should first drive to the docking area. If you are already in the docking area, proceed to the next step, that is, use the landing strategy under the aforementioned docking area (not yet in contact with the shore) and the landing strategy under the docking area (contact switch trigger) to determine the shore contact along the coast to determine whether it is passable. If it is determined that it can be passed, execute the docking action. When arriving at the landing area, jump to the landing state. If it cannot be passed, jump to the near-shore state. If a task interruption signal is received, jump to the standby state.

[0142] When entering the landing state, you should first drive to the landing area. If you are already in the landing area, proceed to the next step, that is, use the plan in the landing strategy under the landing area to detect contact and immersion. If it is determined that it can pass, execute the landing action. When successfully landing, jump to the landing state. If it cannot pass, jump to the docking state. If a mission interruption signal is received, jump to the standby state.

[0143] When entering the landing state, it will wait for further instructions. If there is no further instruction, it will jump to the standby state. If it receives the command to switch to land mode, it will exit the entire landing system. When leaving the landing state, it will perform the drainage action.

[0144] When entering the abnormal state, first perform fault diagnosis to determine whether it is a system fault or a task that cannot be executed. Then perform fault handling actions. After the abnormal handling is completed, jump to the standby state.

[0145] Compared with the prior art, the autonomous landing device and method based on an amphibious platform provided by the present invention has the following advantages:

[0146] (1) The complete set of autonomous landing solutions for amphibious platforms facing unknown underwater beach terrain includes hardware deployment solution, perception area adjustment solution, landing strategy in far-shore area, landing strategy in near-shore area (based on beach category), landing strategy in near-shore area (based on beach terrain), landing strategy in approaching area (not yet in contact with the beach), landing strategy in approaching area (contact switch trigger), landing strategy in landing area, and landing system state machine design.

[0147] (2) The amphibious platform is a motion platform composed of a water propulsion system and a land walking system, and its specific form can be an amphibious vehicle or an amphibious robot. The specific form of the water propulsion system can be a propeller type, a jet pump type, or a paddle type. The specific form of the land walking system can be a flat crawler type, a triangular crawler type, a wheel type, or a leg-foot type.

[0148] (3) In the landing strategy, the landing point is determined by combining laser, vision and touch.

[0149] (4) In the landing strategy in the far-shore area, the shore contour detected by the navigation radar is combined with the known nautical chart information to generate a rough path and update the path in real time, and make corresponding action plans.

[0150] (5) In the landing strategy in the nearshore area, camera data is used to detect the beach type, select the landing point, and make corresponding actions.

[0151] (6) In the landing strategy in the nearshore area, laser radar data is used to draw an above-water beach elevation map and estimate the underwater beach topography, forming a basis for the passability of the beach and making corresponding action plans.

[0152] (7) In the landing strategy in the docking area, the passability of the beach is judged by the combined information of the contact of the land walking system and the contact of the contact switch, and a plan for corresponding actions is made.

[0153] (8) In the landing strategy under the landing area, the combined information of the land walking system contact, the contact switch contact, and the immersion sensor is used to judge the passability of the beach and the success of landing, and a plan for taking corresponding actions.

[0154] (9) In the design of the landing system state machine, the state division method includes eight states: standby, far shore, near shore, docking, landing, landing, return and abnormal.

[0155] (10) In the design of the landing system state machine, the association method of the states includes the action execution of each state and the jump conditions between states.

[0156] Therefore, the present invention proposes an autonomous landing scheme for amphibious platforms for unknown underwater beach terrain, which takes into account the unknown underwater beach terrain, uses a variety of sensors to estimate the terrain and determine contact, and proposes corresponding action strategies to improve landing safety.

[0157] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0158] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. An autonomous landing method based on an amphibious platform, characterized in that: Setting a target location and setting a first distance threshold and a second distance threshold; Determine the distance between the position of the amphibious platform and the intersection point of the initial beach contour obtained from the electronic nautical chart; the intersection point of the initial beach contour is the point where the straight line where the position of the amphibious platform and the target position are located intersects the initial beach contour; When the distance is greater than the first distance threshold, obtaining obstacle information in the electronic nautical chart according to the shore contour data output by the navigation radar; Generate a first driving path according to the obstacle information and the target position, and update the distance; When the distance is less than or equal to the first distance threshold and greater than the second distance threshold, determining the beach type according to the beach image output by the camera; According to the geometric features of the beach output by the laser radar, an elevation map is established to determine the beach topography; Generate a second driving path according to the beach type and the beach terrain, and update the distance; When the distance is less than or equal to the second distance threshold, the successful landing target position is determined according to the position relationship between the bottom of the amphibious platform and the ground output by the contact switch and the position relationship between the bottom of the amphibious platform and the water surface output by the immersion sensor; The autonomous landing method based on an amphibious platform is applied to an autonomous landing device based on an amphibious platform, and the device comprises: A sensor assembly, including a navigation radar, a camera, a laser radar, a combined navigator, a water immersion sensor and a contact switch, for obtaining data information of the autonomous landing of the amphibious platform; the water immersion sensor and the contact switch are both arranged at the bottom of the amphibious platform; the navigation radar, the camera and the laser radar are all arranged on a supporting assembly; The navigation radar is used to obtain the beach contour for the autonomous landing of the amphibious platform; The camera is used to obtain beach images of the amphibious platform autonomously landing; The laser radar is used to detect the geometric features of the beach for the autonomous landing of the amphibious platform; The integrated navigator is used to obtain the position and posture data of the amphibious platform for autonomous landing; The immersion sensor is used to obtain the positional relationship between the bottom of the amphibious platform and the water surface; the positional relationship with the water surface includes being out of the water surface and not out of the water surface; The contact switch is used to obtain the positional relationship between the bottom of the amphibious platform and the ground; the positional relationship between the bottom of the amphibious platform and the ground includes touching the ground and not touching the ground; A support assembly is arranged above the roof of the amphibious platform and is used to adjust the posture of the sensor assembly, specifically comprising: The support assembly includes a lifting rod and an adjustable support; the lifting rod is vertically fixed above the roof of the amphibious platform; the adjustable support is vertically fixed on the lifting rod; the navigation radar is arranged on the lifting rod; the camera and the laser radar are both arranged on the adjustable support; A control component is arranged inside the amphibious platform and is connected to the support component and the sensor component respectively, and is used to generate a motion control instruction according to the data information acquired by the sensor component, and send the motion control instruction to the control system of the amphibious platform, and the control system controls the amphibious platform to autonomously land according to the motion control instruction, specifically including: A central gateway, connected to the sensor assembly, for transmitting data information collected by the sensor assembly; An industrial computer, connected to the central gateway, for generating motion control instructions according to the data information and sending the motion control instructions to the control system of the amphibious platform; Specifically, the industrial computer generates motion control instructions based on the information provided by the sensor data and sends them to the vehicle controller; the vehicle controller converts the upper-level control instructions into lower-level control instructions and sends them to the water propulsion system and the land walking system. The water propulsion system and the land walking system execute the instructions and feedback the status.

2. The autonomous landing method based on an amphibious platform according to claim 1 is characterized in that: The step of generating a first driving path according to the obstacle information and the target position, and updating the distance, specifically includes: Obtaining a two-dimensional occupancy grid map according to the obstacle information and the target position; According to the two-dimensional occupancy grid map, an A* algorithm is used to obtain a path planning result; the path planning result includes a successful planning and an unsuccessful planning; When the path planning result is that the planning is unsuccessful, the amphibious platform travels a first set distance along the beach contour and updates the obstacle information; When the path planning result is successful, the first driving path is obtained and the distance is updated.

3. The autonomous landing method based on an amphibious platform according to claim 1 is characterized in that: When the distance is less than or equal to the first distance threshold and greater than the second distance threshold, determining the beach type according to the beach image output by the camera specifically includes: When the distance is less than or equal to the first distance threshold and greater than the second distance threshold, acquiring data collected by the camera; According to the data collected by the camera, the target detection yolov5 algorithm is applied to identify the beach type; the beach types include hard beaches, soft beaches and reef beaches.

4. The autonomous landing method based on an amphibious platform according to claim 1 is characterized in that: The method of establishing an elevation map and determining the beach topography based on the beach geometric features output by the laser radar specifically includes: Obtain the geometric characteristics of the beach output by the laser radar; According to the geometric features of the beach, an elevation map is established for the beach topography above water, thereby obtaining the beach topography above water; According to the elevation map, the underwater shore topography is fitted in the form of a quadratic parabola using the least squares method to obtain the underwater shore topography; The beach topography is determined based on the above-water beach topography and the underwater beach topography.

5. The autonomous landing method based on an amphibious platform according to claim 3 is characterized in that: The generating a second driving path according to the beach type and the beach terrain, and updating the distance, specifically includes: Eliminate the data of the beach type being a reef beach from the data collected by the camera, and obtain passable beach type data; According to the passable beach type data, the beach terrain is screened to obtain a passable beach terrain; According to the passable beach terrain, an A* algorithm is used to obtain a path planning result; the path planning result includes a successful planning and an unsuccessful planning; When the path planning result is that the planning is unsuccessful, the amphibious platform travels a second set distance along the beach contour and updates the beach type; When the path planning result is successful, the second driving path is obtained and the distance is updated.

6. The autonomous landing method based on an amphibious platform according to claim 1 is characterized in that: When the distance is less than or equal to the second distance threshold, determining the successful landing target position according to the position relationship between the bottom of the amphibious platform and the ground output by the contact switch and the position relationship between the bottom of the amphibious platform and the water surface output by the immersion sensor, specifically includes: When the distance is less than or equal to the second distance threshold, obtaining the positional relationship between the bottom of the amphibious platform and the ground output by the contact switch; the positional relationship between the bottom of the amphibious platform and the ground includes touching the ground and not touching the ground; When the position relationship between the bottom of the amphibious platform and the ground is touching the ground, the amphibious platform travels along the second driving path for a set time, and obtains the position and posture data of the amphibious platform output by the integrated navigation system; According to the posture data, determining whether the position of the amphibious platform is elevated; If the position of the amphibious platform rises, the position relationship between the bottom of the amphibious platform and the water surface output by the immersion sensor is obtained; the position relationship between the bottom of the amphibious platform and the water surface includes being out of water and not out of water; when the position relationship between the bottom of the amphibious platform and the water surface is out of water, the target position for successful landing is determined.

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