Unmanned ship automatic collision avoidance method based on storm hybrid power

Abstract

The invention designs an unmanned ship automatic collision avoidance method based on wind and wave hybrid power. The method comprises the steps that 1, a water surface target is received through an AIS receiver to be processed; 2, calculating related collision avoidance information by using an analytic geometry method, calculating a current navigation situation, and obtaining target intersection features; 3, judging targets with collision risks by using a collision risk assessment method, and carrying out target risk grade division; 4, determining an avoidance operation needing to be carried out according to the danger level in combination with the danger target encounter situation; 5, for the situation needing active avoidance, giving an avoidance decision by combining the control characteristics of the boat and applying an intelligent decision-making method, and performing active avoidance; 6, judging the re-flight opportunity; and 7, executing course recovery operation. Aiming at the under-actuated control characteristic of the wind and wave hybrid unmanned ship, the invention provides the automatic collision avoidance method based on the wind and wave hybrid unmanned ship, the navigation power and the navigation safety are fully considered, and the method has good practical application value.

Description

Technical Field

[0001] The invention belongs to the field of autonomous navigation of small unmanned boats, in particular to an automatic collision avoidance method for unmanned boats based on wind and wave hybrid power. Background Art

[0002] The wind-wave hybrid unmanned boat can be used for long-duration, long-distance continuous marine operations due to its small size, low power consumption, and strong wind and wave resistance. It is mainly used for tasks in the field of meteorological and hydrological environmental information detection. Its communication with the shore station control system mostly adopts Beidou communication, Tiantong and other communication methods, so it has high requirements for control autonomy. Automatic collision avoidance is part of the autonomous navigation of unmanned boats and one of the key technologies to achieve autonomous navigation of surface unmanned boats. It means that the unmanned boat receives information from navigation sensors, target sensors and other information in real time during navigation, and combines its own control characteristics to determine the movement status of obstacles encountered on the navigation route. For targets in a collision avoidance danger situation, different collision avoidance measures are adopted according to the danger level to achieve the purpose of safe navigation.

[0003] At present, most surface unmanned boats use vector thrusters as their main power source. Due to their small size, flexible control and strong maneuverability, small and medium-sized unmanned boats usually adopt active avoidance. However, the characteristics of wind-wave hybrid unmanned boats are: the main power source is a hydrodynamic glider, which has the characteristics of under-driven control, low speed and poor maneuverability. The existing avoidance method is not suitable for wind-wave hybrid unmanned boats. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and to propose an automatic collision avoidance method for an unmanned boat based on wind and wave hybrid power, which has a fast execution speed and can ensure the navigation safety of the unmanned boat.

[0005] The above-mentioned object of the present invention is achieved by the following technical solutions:

[0006] An automatic collision avoidance method for an unmanned boat based on wind-wave hybrid power comprises the following steps:

[0007] Step 1: Target reception and processing: Surface targets are received and processed by the AIS receiver to form a target structure including MMSI (Maritime Mobile Service Identification Code), latitude and longitude, distance, azimuth, heading, and speed information, and stored in a calculation linked list that can be quickly polled;

[0008] Step 2: Navigation situation calculation: Based on the position and motion parameters of the own boat and the target, the analytical geometry method is used to calculate the relevant collision avoidance information, calculate the current navigation situation, and obtain the target intersection characteristics;

[0009] Step 3: Determine and evaluate collision risk: Determine whether there is a target with collision risk. If so, use the collision risk assessment method to determine whether there is a target with collision risk and classify the target risk level, and then go to step 4. If not, go to step 1.

[0010] Step 4: Determine whether to perform avoidance operations based on the danger level and the situation of the dangerous target. If the current danger level is lower than level 2, go to step 1 to continue monitoring the target situation. If the current danger level is not lower than level 2, go to step 5.

[0011] Step 5: Avoidance decision generation: For situations that require active avoidance, an avoidance decision is made using an intelligent decision-making method in combination with the boat's maneuvering characteristics and sent to the control unit to execute active avoidance;

[0012] Step 6: Determine the timing of resuming navigation: call the navigation situation calculation algorithm to predict whether there is a dangerous ship after resuming the original course; if the dangerous ship no longer exists, it means that the timing of resuming navigation has arrived, go to step 7; otherwise, go to step 5;

[0013] Step 7: The return-to-course command is sent to the control unit for execution. The heading recovery operation is performed and then go to step 1.

[0014] Moreover, in step 2: at any time, the closest approach distance DCPA and the closest approach time TCPA between the own ship o and the target ship T can be calculated by the following equations:

[0015]

[0016] (x T ,y T ) is the coordinate of the target ship in the ship's o coordinate system, θ r is the relative azimuth between own ship and target ship.

[0017] Moreover, the collision risk assessment method used in step 3 takes into account the maneuverability parameters of the unmanned boat, meteorological environmental factors and relative motion parameters, quantifies the safe encounter distance, and divides the risk level into 5 levels through geometric theory, namely level 1 safety, level 2 safety, level 3 safety, level 4 unsafe, and level 5 unsafe. The corresponding safe encounter distance thresholds are collision avoidance danger critical distance, collision avoidance danger distance, collision avoidance urgent critical distance, collision avoidance urgent distance and urgent danger critical distance.

[0018] Moreover, in step 4, different treatment operations are adopted according to the different danger levels of the ship, specifically:

[0019] Level 0 security: maintain current control and target situation monitoring;

[0020] Level 1 safety: Maintain current maneuvers and determine whether the target ship takes collision avoidance measures;

[0021] Level 2 safety: Active collision avoidance is activated, using hydrodynamic glider power;

[0022] Level 3 safety: Active collision avoidance is activated, using vector thruster power;

[0023] Level 4: less safe: active collision avoidance is initiated, using vector thruster power;

[0024] Level 5: Unsafe: Active collision avoidance is initiated, using vector thruster power;

[0025] When the DCPA of the own ship enters the collision avoidance danger distance and TCPA>0, there is a collision risk with the target ship and the collision avoidance control process is entered.

[0026] Furthermore, in step 5, the avoidance decision includes the steering angle AC, which is calculated as:

[0027]

[0028] Among them, i is the key ship to be avoided, Ct is the target ship heading, Vt is the target ship speed, Co is the ship heading, and Crn is the predicted new relative motion heading. The calculation method is:

[0029]

[0030] Under the premise of meeting safety, the track deviation after the collision avoidance decision is minimized as the economic indicator. Based on the quantitative model of the steering timing Tsr(AC), AC and the predicted re-entry timing Tr(AC), a dynamic optimization objective function J(s) is established for autonomous collision avoidance:

[0031]

[0032] Where N = (TL-Tisr[n]) / ΔT, ΔT is the search step length; A is the behavior set of the ship in the optimization search space T∈{Tisr[n], TL}; TL is the minimum Tln[i], that is, TL = min{Tln[i]}, i = 1, 2, ... M, M is the number of dangerous target ships; S is the state set; V 0 is the ship's speed, u * It is the optimal decision to avoid collision.

[0033] The advantages and positive effects of the present invention are:

[0034] The automatic collision avoidance method for an unmanned boat based on a wind-wave hybrid power provided by the present invention calculates the current navigation situation and obtains the target intersection characteristics through the geographic location information and motion situation information of the boat and the target such as a navigation sensor and a target sensor according to the under-actuated control characteristics of the wind-wave hybrid power unmanned boat, and takes appropriate collision avoidance measures according to the danger level and the dangerous target encounter situation. The navigation test shows that the method can realize the automatic collision avoidance of the unmanned boat based on a wind-wave hybrid power and ensure the safe navigation of the unmanned boat. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is a flow chart of the collision avoidance process of the present invention;

[0036] Figure 2 It is the scheme framework of the present invention;

[0037] Figure 3 It is a rendering of the automatic collision avoidance of the present invention. DETAILED DESCRIPTION

[0038] In order to make the purpose, implementation scheme and advantages of the present invention clearer, the implementation process of the present invention is clearly and completely described below in conjunction with specific examples and drawings. Obviously, the implementation examples described are only part of the implementation examples of the present invention, but not all of the implementation examples.

[0039] An automatic collision avoidance method for unmanned boats based on wind and wave hybrid power, see Figure 1-Figure 3 , the invention point is: comprising the following steps:

[0040] Step 1: Target reception and processing: Surface targets are received and processed by the AIS receiver to form a target structure including MMSI, latitude and longitude, distance, azimuth, heading, and speed information, and stored in a calculation linked list that can be quickly polled;

[0041] Step 2: Navigation situation calculation: Based on the position and motion parameters of the own boat and the target, the analytical geometry method is used to calculate the relevant collision avoidance information, calculate the current navigation situation, and obtain the target intersection characteristics; where:

[0042] At any time, the closest approach distance DCPA and the closest approach time TCPA between the own ship o and the target ship T can be calculated by the following equations:

[0043]

[0044] (x T ,y T ) is the coordinate of the target ship in the ship's o coordinate system, θ r is the relative azimuth between own ship and target ship.

[0045] Step 3: Determine and evaluate the collision risk: Determine whether there is a target in collision risk. If so, use the collision risk assessment method to determine whether there is a target in collision risk and classify the target risk level, and go to step 4. If not, go to step 1. Specifically: The collision risk assessment method used takes into account the maneuverability parameters of the unmanned boat, meteorological environmental factors and relative motion parameters, quantifies the safe encounter distance, and divides the risk level into 5 levels through geometric theory, namely level 1 safety, level 2 safety, level 3 safety, level 4 unsafe, and level 5 unsafe. The corresponding safe encounter distance thresholds are collision avoidance risk critical distance, collision avoidance risk distance, collision avoidance emergency critical distance, collision avoidance emergency distance and emergency risk critical distance. See Table 1:

[0046] Step 4: Determine whether avoidance operations are required based on the danger level and the situation of encountering dangerous targets. If the current danger level is lower than level 2, go to step 1 to continue monitoring the target situation. If the current danger level is not lower than level 2, go to step 5. Otherwise, go to step 1. Specifically: Different processing operations are adopted according to the different danger levels of the ship, see Table 1, specifically:

[0047] Level 0 security: maintain current control and target situation monitoring;

[0048] Level 1 safety: Maintain current maneuvers and determine whether the target ship takes collision avoidance measures;

[0049] Level 2 safety: Active collision avoidance is activated, using hydrodynamic glider power;

[0050] Level 3 safety: Active collision avoidance is activated, using vector thruster power;

[0051] Level 4: less safe: active collision avoidance is initiated, using vector thruster power;

[0052] Level 5: Unsafe: Active collision avoidance is initiated, using vector thruster power.

[0053] When the DCPA of the own ship enters the collision avoidance danger distance and TCPA>0, there is a collision risk with the target ship and the collision avoidance control process is entered.

[0054] Step 5: Avoidance decision generation: For situations that require active avoidance, an avoidance decision is made using an intelligent decision-making method in combination with the boat's maneuvering characteristics and sent to the control unit to perform active avoidance; the avoidance decision includes the steering angle AC, which is calculated as follows:

[0055]

[0056] Among them, i is the key ship to be avoided, Ct is the target ship heading, Vt is the target ship speed, Co is the ship heading, and Crn is the predicted new relative motion heading. The calculation method is:

[0057]

[0058] Under the premise of meeting safety, the track deviation after the collision avoidance decision is minimized as the economic indicator. Based on the quantitative model of the steering timing Tsr(AC), AC and the predicted re-entry timing Tr(AC), a dynamic optimization objective function J(s) is established for autonomous collision avoidance:

[0059]

[0060] Among them, N = (TL-Tisr[n]) / ΔT, ΔT is the search step size; A is the behavior set of the ship in the optimization search space T∈{Tisr[n], TL}; TL is the smallest Tln[i], that is, TL=min{Tln[i]}, i=1,2,…M, M is the number of dangerous target ships; S is the state set; V0 is the speed of the ship, and u* is the optimal decision for collision avoidance.

[0061] Step 6: Determine the timing of resuming navigation: Call the navigation situation calculation algorithm to predict whether there is a dangerous ship after resuming the original course. If the dangerous ship no longer exists, it means that the timing of resuming navigation has arrived, and go to step 7; otherwise, go to step 5;

[0062] Step 7: The return-to-course command is sent to the control unit for execution. The heading recovery operation is performed and then go to step 1.

[0063] Table 1: Classification of hazard registration and corresponding control methods

[0064]

[0065] In summary, the present invention is aimed at a wind-wave hybrid power unmanned boat, in which the main power is a hydrodynamic glider and the auxiliary power is a vector thruster. Taking into account the characteristics of its under-driven control mode, low speed and poor maneuverability, passive avoidance rather than active avoidance is given priority during the avoidance process. It is very necessary to design an automatic collision avoidance method suitable for an unmanned boat based on wind-wave hybrid power, which is also an innovative work.

[0066] It should be emphasized that the embodiments described in the present invention are illustrative rather than restrictive. Therefore, the present invention includes but is not limited to the embodiments described in the specific implementation manner. Any other implementation manners derived by those skilled in the art based on the technical solution of the present invention also fall within the scope of protection of the present invention.

Claims

1. An automatic collision avoidance method for an unmanned boat based on wind and wave hybrid power, characterized in that: The following steps are involved: Step 1: Target reception and processing: Surface targets are received and processed by the AIS receiver to form a target structure including MMSI, latitude and longitude, distance, azimuth, heading, and speed information, and stored in a calculation linked list that can be quickly polled; Step 2: Navigation situation calculation: Based on the position and motion parameters of the own boat and the target, the analytical geometry method is used to calculate the relevant collision avoidance information, calculate the current navigation situation, and obtain the target intersection characteristics; Step 3: Determine and evaluate collision risk: Determine whether there is a target with collision risk. If so, use the collision risk assessment method to determine whether there is a target with collision risk and classify the target risk level, and then go to step 4. If not, go to step 1. Step 4: Confirm the avoidance operation required based on the danger level and the situation of the dangerous target. If the current danger level is lower than level 2, go to step 1 to continue monitoring the target situation. If the current danger level is not lower than level 2, go to step 5 to perform the avoidance operation. Step 5: Avoidance decision generation: For situations that require active avoidance, an avoidance decision is made using an intelligent decision-making method in combination with the boat's maneuvering characteristics and sent to the control unit to execute active avoidance; Step 6: Determine the timing of resuming navigation: call the navigation situation calculation algorithm to predict whether there is a dangerous ship after resuming the original course; if the dangerous ship no longer exists, it means that the timing of resuming navigation has arrived, and go to step 7; Otherwise go to step 5; Step 7: The return-to-course command is sent to the control unit for execution. The heading recovery operation is performed and then go to step 1.

2. The automatic collision avoidance method for an unmanned boat based on wind and wave hybrid power according to claim 1 is characterized in that: In step 2: At any time, the closest approach distance DCPA and the closest approach time TCPA between the own ship o and the target ship T can be calculated by the following equations: (x T ,y T ) is the coordinate of the target ship in the ship's o coordinate system, θ r is the relative azimuth between own ship and target ship.

3. The automatic collision avoidance method for unmanned boats based on wind and wave hybrid power according to claim 2 is characterized in that: The collision risk assessment method used in step 3 takes into account the maneuverability parameters, meteorological environmental factors and relative motion parameters of the unmanned boat, quantifies the safe encounter distance, and divides the risk level into 5 levels through geometric theory, namely level 1 safety, level 2 safety, level 3 safety, level 4 unsafe, and level 5 unsafe. The corresponding safe encounter distance thresholds are collision avoidance danger critical distance, collision avoidance danger distance, collision avoidance urgent critical distance, collision avoidance urgent distance and urgent danger critical distance.

4. The automatic collision avoidance method for unmanned boats based on wind and wave hybrid power according to claim 1 is characterized in that: In step 4, different treatment operations are adopted according to the different danger levels of the ship, specifically: Level 0 security: maintain current control and target situation monitoring; Level 1 safety: Maintain current maneuvers and determine whether the target ship takes collision avoidance measures; Level 2 safety: Active collision avoidance is activated, using hydrodynamic glider power; Level 3 safety: Active collision avoidance is activated, using vector thruster power; Level 4: less safe: active collision avoidance is initiated, using vector thruster power; Level 5: Unsafe: Active collision avoidance is initiated, using vector thruster power; When the DCPA of the own ship enters the collision avoidance danger distance and TCPA>0, there is a collision risk with the target ship and the collision avoidance control process is entered.

5. The automatic collision avoidance method for unmanned boats based on wind and wave hybrid power according to claim 1 is characterized in that: In step 5, the avoidance decision includes the steering angle AC, which is calculated as: Among them, i is the key ship to be avoided, Ct is the target ship heading, Vt is the target ship speed, Co is the ship heading, and Crn is the predicted new relative motion heading. The calculation method is: Under the premise of meeting safety, the track deviation after the collision avoidance decision is minimized as the economic indicator. Based on the quantitative model of the steering timing Tsr(AC), AC and the predicted re-entry timing Tr(AC), a dynamic optimization objective function J(s) is established for autonomous collision avoidance: Where N = (TL-Tisr[n]) / ΔT, ΔT is the search step length; A is the behavior set of the ship in the optimization search space T∈{Tisr[n], TL}; TL is the minimum Tln[i], that is, TL = min{Tln[i]}, i = 1, 2, ... M, M is the number of dangerous target ships; S is the state set; V0 is the speed of the ship, u * It is the optimal decision to avoid collision.

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