Attitude synchronization method for landing of ship-borne unmanned rotorcraft

Abstract

The invention discloses an attitude synchronization method for landing of a ship-borne rotor unmanned aerial vehicle, and relates to the technical field of unmanned aerial vehicle landing regulation and control, and the method comprises the following steps: 1, firstly, respectively collecting data of a ship-borne AHRS system and an airborne sensor, and after the data collection is completed, carrying out attitude synchronization on the ship-borne AHRS system and the airborne sensor; the data of the ship-descending AHRS system and the data collected by the airborne sensor are fused, and the relative attitude deviation and the position deviation of the ship are estimated after fusion. According to the method, the requirement of the ship-based unmanned aerial vehicle for a landing window in the landing stage is lowered, the computing power requirement for an airborne computer of a mobile platform is lowered, cost, weight and energy consumption are saved, higher safety is achieved, the collision risk caused by ship attitude changes in the landing process is reduced, the automation degree of landing is improved, and the probability that manual catching is needed is lowered.

Description

Technical Field

[0001] The invention relates to the technical field of unmanned aerial vehicle landing control, and in particular to a landing attitude synchronization method for a shipborne rotor unmanned aerial vehicle. Background Art

[0002] At present, ship-borne drones have played an important role in the fields of maritime search and rescue, reconnaissance, and material transportation. In the application of ship-borne drones, it is a difficult task to safely and reliably realize the recovery and landing of drones. The traditional ship-borne landing method of drones requires the drone to wait for a suitable landing window after returning to the vicinity of the ship. Due to the influence of factors such as wind and waves and the state of the drone, this method has certain limitations in the actual application process.

[0003] Most of the existing drones that support vertical take-off and landing are multi-rotor drones or compound-wing drones. During the vertical take-off and landing stage, they are all powered by batteries. Due to the limited energy density of existing battery technology, the battery power available for the landing stage is limited. When the ship's sailing environment is windy and choppy, it takes a long time to wait, and the power of the drone will decrease as the power is consumed, increasing the risk of the drone failing to land on the ship;

[0004] In addition, in the sea environment, the wind and waves change greatly. If the ship's attitude changes significantly when the drone is about to touch down, problems such as landing gear damage may easily occur. Summary of the invention

[0005] The purpose of the present invention is to provide a landing attitude synchronization method for a shipborne rotor UAV to solve the problems raised in the above background technology.

[0006] To achieve the above object, the present invention provides the following technical solution: a method for attitude synchronization of landing of a shipborne rotor UAV, comprising the following steps:

[0007] Step 1: First, the data of the shipborne AHRS system and the airborne sensor are collected separately. After the data collection is completed, the data of the shipborne AHRS system is fused with the data collected by the airborne sensor. After the fusion, the relative attitude deviation and position deviation of the ship are estimated;

[0008] A laser rangefinder sensor is used to collect the flight altitude measurement value of the UAV from the deck. The airborne AHRS is responsible for collecting the attitude and position information of the UAV, and the shipborne AHRS is responsible for collecting the attitude and position information of the ship. The airborne camera is used to monitor and shoot the real-time situation on the deck to collect real-time data. When the above information is transmitted to the airborne computer via the data link, the airborne computer synchronizes the data according to the timestamp of the above information, and establishes a Kalman filter to evaluate the attitude deviation and relative distance d between the UAV and the ship.

[0009] Step 2: Using visual attitude fusion technology, the relative position, relative attitude and relative angular velocity relationship between the UAV and the landing platform are obtained. In order to realize the landing of the UAV on the ship, it is necessary to ensure that the relative position, relative attitude and relative angular velocity relationship between the ship and the aircraft are controlled within a reasonable range during landing;

[0010] Due to the limitation of the deck area of ​​the ship, the relative position deviation during landing is controlled within the range of 0.5-1 meter. In order to reduce the impact on the ship when landing, it is necessary to ensure that its relative speed is less than 0.2m / s and the relative angular velocity is less than 5° / s.

[0011] Preferably, in step 1, a multi-scale visual tag is set on the shipborne landing platform, and the visual sensor carried by the drone can detect the tag at different heights and stably calculate the center point coordinates of the tag (Pt x , Pt y ), assuming that the intrinsic parameter matrix of the camera is K;

[0012]

[0013] The coordinates of the visual label in the camera coordinate system are:

[0014]

[0015] According to the above formula, the relative position relationship P between the UAV and the ship can be obtained: rel、| , relative attitude Att rel and the relative angular rate Rate rel .

[0016] Preferably, in the implementation process of step 2, an attitude synchronization enable signal calculated according to the altitude is added. When the flight altitude is low, the ship attitude and the UAV attitude can be synchronized in a short time to reduce the impact caused by the angular velocity difference during landing. At the same time, the position error of the landing point can also be controlled within a reasonable range, avoiding the traditional landing method, which usually waits for a suitable landing window. During landing, the attitude controller is used to maintain the position of the UAV, resulting in a large difference in the position point range of the UAV landing point.

[0017] Preferably, in step 2, an attitude synchronizer design of the airborne controller in the descent phase is adopted. When the UAV is higher than the loading landing platform, the attitude synchronization function is turned off, and the UAV changes its attitude, thereby changing the thrust component of the UAV in each direction, thereby tracking the landing point position of the carrier-based platform.

[0018] Preferably, in the step 2, when the UAV descends to the critical height, the UAV attitude synchronization function is used. In the UAV attitude synchronization mode, the UAV uses the collected ship attitude as the expected attitude to ensure that the attitude of the UAV is synchronized with the shipborne platform when landing, thereby ensuring the safety of the UAV in turbidity flow. When tracking the ship attitude, the UAV will simultaneously monitor the position error between the UAV and the shipborne platform. When the position error is greater than a threshold, the landing program is exited.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The present invention realizes an attitude synchronization algorithm during the descent of a shipborne UAV, so as to reduce the requirements of the ship attitude, wind and waves and other conditions when the UAV lands, and improve the landing success rate and safety of the shipborne UAV. The visual attitude fusion technology and the attitude real-time tracking technology are used to calculate the attitude deviation and position deviation between the UAV and the shipborne platform, and in the landing phase, the attitude deviation and position deviation between the UAV and the shipborne landing platform are controlled in real time. The sea-air integrated inertial data fusion technology is used to estimate the attitude deviation and position deviation, and the attitude real-time tracking technology is used to control the relative attitude and position of the UAV and the shipborne landing platform, so as to realize the control of the UAV in the landing phase. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Provides an overall structural diagram for an embodiment of the present invention;

[0022] Figure 2 A flow chart of the technical solution for spatial visual posture fusion provided by an embodiment of the present invention;

[0023] Figure 3 A flow chart of a design scheme for an attitude synchronizer of an airborne controller during a descent phase provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0024] 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.

[0025] See also Figure 1-3 The present invention provides a technical solution: a method for synchronizing the landing posture of a shipborne rotor UAV, comprising the following steps:

[0026] Step 1: First, the data of the shipborne AHRS system and the airborne sensor are collected separately. After the data collection is completed, the data of the shipborne AHRS system is fused with the data collected by the airborne sensor. After the fusion, the relative attitude deviation and position deviation of the ship are estimated;

[0027] A laser rangefinder sensor is used to collect the flight altitude measurement value of the UAV from the deck. The airborne AHRS is responsible for collecting the attitude and position information of the UAV, and the shipborne AHRS is responsible for collecting the attitude and position information of the ship. The airborne camera is used to monitor and shoot the real-time situation on the deck to collect real-time data. When the above information is transmitted to the airborne computer via the data link, the airborne computer synchronizes the data according to the timestamp of the above information, and establishes a Kalman filter to evaluate the attitude deviation and relative distance d between the UAV and the ship.

[0028] Step 2: Using visual attitude fusion technology, the relative position, relative attitude and relative angular velocity relationship between the UAV and the landing platform are obtained. In order to realize the landing of the UAV on the ship, it is necessary to ensure that the relative position, relative attitude and relative angular velocity relationship between the ship and the aircraft are controlled within a reasonable range during landing;

[0029] Due to the limitation of the deck area of ​​the ship, the relative position deviation during landing is controlled within the range of 0.5-1 meter. In order to reduce the impact on the ship when landing, it is necessary to ensure that its relative speed is less than 0.2m / s and the relative angular velocity is less than 5° / s.

[0030] In step 1, a multi-scale visual tag is set on the shipborne landing platform. The visual sensor carried by the drone can detect the tag at different heights and stably calculate the center point coordinates of the tag (Pt x , Pt y ), assuming that the intrinsic parameter matrix of the camera is K;

[0031]

[0032] The coordinates of the visual label in the camera coordinate system are:

[0033]

[0034] According to the above formula, the relative position relationship P between the UAV and the ship can be obtained: rel、| , relative attitude Att rel and the relative angular rate Rate rel .

[0035] In step 2, an attitude synchronization enable signal calculated according to the altitude is added during the implementation process. When the flight altitude is low, the ship attitude and the UAV attitude can be synchronized in a short time to reduce the impact caused by the angular velocity difference during landing. At the same time, the position error of the landing point can also be controlled within a reasonable range, avoiding the traditional landing method, which usually waits for a suitable landing window. During landing, the attitude controller is used to maintain the position of the UAV, resulting in a large difference in the position point range of the UAV landing point.

[0036] In step 2, the attitude synchronizer design of the airborne controller in the descent phase is adopted. When the UAV is higher than the loading landing platform, the attitude synchronization function is turned off. The UAV changes its attitude, thereby changing the thrust component of the UAV in each direction, to achieve the landing point position tracking of the carrier-based platform.

[0037] In step 2, when the UAV descends to the critical height, the UAV attitude synchronization function is used. In the UAV attitude synchronization mode, the UAV uses the collected ship attitude as the expected attitude to ensure that the attitude of the UAV is synchronized with the shipborne platform when landing, ensuring the safety of the UAV. When tracking the ship attitude, the UAV will simultaneously monitor the position error between the UAV and the shipborne platform. When the position error is greater than the threshold, the landing program is exited. The above technical solution is used to track the ship attitude during the landing phase of the shipborne UAV to achieve safe landing of the UAV on the shipborne landing platform.

[0038] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0039] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for synchronizing the landing posture of a shipborne rotor drone, characterized in that The following steps are involved: Step 1: First, the data of the shipborne AHRS system and the airborne sensor are collected separately. After the data collection is completed, the data of the shipborne AHRS system is fused with the data collected by the airborne sensor. After the fusion, the relative attitude deviation and position deviation of the ship are estimated; A laser rangefinder sensor is used to collect the flight altitude measurement value of the UAV from the deck. The airborne AHRS is responsible for collecting the attitude and position information of the UAV, and the shipborne AHRS is responsible for collecting the attitude and position information of the ship. The airborne camera is used to monitor and shoot the real-time situation on the deck to collect real-time data. When the above information is transmitted to the airborne computer via the data link, the airborne computer synchronizes the data according to the timestamp of the above information, and establishes a Kalman filter to evaluate the attitude deviation and relative distance d between the UAV and the ship. Step 2: Using visual attitude fusion technology, the relative position, relative attitude and relative angular velocity relationship between the UAV and the landing platform are obtained. Due to the limitation of the ship deck area, the relative position deviation during landing is controlled within the range of 0.5-1 meter. In order to reduce the impact on the ship when landing, the relative speed must be less than 0.2m / s and the relative angular velocity must be less than 5° / s.

2. The method for attitude synchronization of landing of a carrier-based rotary-wing UAV according to claim 1, characterized in that: In step 1, a multi-scale visual tag is set on the shipborne landing platform. The visual sensor carried by the drone can detect the tag at different heights and stably calculate the center point coordinates of the tag (Pt x , Pt y ), assuming that the intrinsic parameter matrix of the camera is K; The coordinates of the visual label in the camera coordinate system are: According to the above formula, the relative position relationship P between the UAV and the ship can be obtained: rel、| , relative attitude Att rel and the relative angular rate Rate rel .

3. The method for attitude synchronization of landing of a carrier-based rotary-wing UAV according to claim 1, characterized in that: In the implementation process of step 2, an attitude synchronization enable signal calculated according to the altitude is added. When the flight altitude is low, the ship attitude and the UAV attitude can be synchronized in a short time to reduce the impact caused by the angular velocity difference during landing. At the same time, the position error of the landing point can also be controlled within a reasonable range.

4. The method for attitude synchronization of landing of a carrier-based rotary-wing UAV according to claim 1, characterized in that: In the step 2, the attitude synchronizer design of the airborne controller in the descent phase is adopted. When the UAV is higher than the loading landing platform, the attitude synchronization function is turned off. The UAV changes its attitude, thereby changing the thrust component of the UAV in each direction, thereby tracking the landing point position of the carrier-based platform.

5. The method for attitude synchronization of landing of a carrier-based rotary-wing UAV according to claim 4, characterized in that: In the step 2, when the UAV descends to the critical height, the UAV attitude synchronization function is used. In the UAV attitude synchronization mode, the UAV uses the collected ship attitude as the expected attitude to ensure that the attitude of the UAV is synchronized with the shipborne platform when landing, ensuring the safety of the UAV. When tracking the ship attitude, the UAV will simultaneously monitor the position error between the UAV and the shipborne platform. When the position error is greater than the threshold, the landing program is exited.

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