Dynamic modeling method for robotic fish with distributed driving pectoral fins

Abstract

The invention relates to the technical field of underwater robot control, in particular to a robotic fish dynamics modeling method with distributed driving pectoral fins, which comprises the following steps: constructing a coordinate system; constructing a kinematic equation of the pectoral fin; the total force and the total torque of the robotic fish are obtained; and establishing a kinetic model of the robotic fish prototype. The dynamic model can be used for controller simulation verification of the robotic fish, and a new research thought is provided for subsequent in-depth research on motion control of the robotic fish with distributed driving pectoral fins.

Description

Technical Field

[0001] The present invention relates to the technical field of underwater robot control, and particularly relates to a method for dynamically modeling a robotic fish with distributed-driven pectoral fins. Background Art

[0002] In the field of modern bionic underwater robot technology, the research on bionic robotic fish is of great significance for the development and protection of marine resources. Bionic robotic fish can flexibly perform tasks in complex underwater environments, such as underwater exploration, water quality detection, coral monitoring, etc., by mimicking the movement mechanisms of real fish. In this context, establishing an accurate dynamic model is crucial for understanding the movement performance of robotic fish and studying their control methods.

[0003] Existing bionic pectoral fin propulsion robotic fish can adopt a pectoral fin mechanism driven by a dual-motor swing-rotation type, or a pectoral fin mechanism driven by multiple motors in a distributed manner. Although the pectoral fin driven by the motor swing-rotation type saves the number of motors, it has certain limitations in terms of movement flexibility and efficiency; the pectoral fin driven by multiple motors in a distributed manner can more precisely control the deformation of the pectoral fin by distributing multiple driving motors at different positions of the pectoral fin, thereby achieving more complex movement patterns and higher propulsion efficiency. However, when the number of motors in the distributed drive changes, how to accurately establish the dynamic model of such a distributed drive system is still a difficult point in current research.

[0004] Therefore, it is necessary to provide a method for dynamically modeling a robotic fish with distributed-driven pectoral fins to solve the above problems. Summary of the Invention

[0005] The present invention provides a method for dynamically modeling a robotic fish with distributed-driven pectoral fins to solve the problem of how to accurately establish the dynamic model of such a distributed drive system when the number of motors in the distributed drive changes.

[0006] The method for dynamically modeling a robotic fish with distributed-driven pectoral fins of the present invention adopts the following technical solutions, including: Establish a ground coordinate system, a carrier coordinate system, a left pectoral fin coordinate system, and a right pectoral fin coordinate system; Based on the method of dividing into micro element strips, establish the kinematic equations of the corresponding pectoral fins in the left pectoral fin coordinate system and the right pectoral fin coordinate system respectively; use the kinematic equations to obtain the positions of the end points of each micro element strip; In the left pectoral fin coordinate system and the right pectoral fin coordinate system, and use the Morison equation to obtain the forces generated by the micro element strips of the corresponding pectoral fins, and obtain the forces and torques generated by each pectoral fin based on the forces generated by the micro element strips; The forces and moments generated by each pectoral fin are transformed into the vehicle coordinate system to obtain the target forces and target moments of each pectoral fin in the vehicle coordinate system; the total force and total moment of the robotic fish are obtained based on the target forces and target moments of the two pectoral fins; Based on the total force and total moment of the robotic fish, a dynamic model of the robotic fish prototype is established using the Fossen equation; where the dynamic model is used to input the velocity and angular velocity of the robotic fish in the vehicle coordinate system to output the position and attitude of the robotic fish in the earth coordinate system.

[0007] Preferably, the steps for establishing the ground coordinate system, vehicle coordinate system, left pectoral fin coordinate system, and right pectoral fin coordinate system are as follows: The axes of the ground coordinate system are fixed to the earth, and the origin of the ground coordinate system is selected at a certain location on the ground. The axis points to the due north direction. The positive direction of the axis is vertically upward. The axis points to the due east direction. The axes of the vehicle coordinate system are fixed to the robotic fish, with the center of buoyancy as the origin of coordinates. The axis points to the head of the robotic fish. The axis points upward. The axis points to the right side of the robotic fish. The left pectoral fin coordinate system has the starting point of the left pectoral fin as the origin of coordinates. The axis points forward. The axis points upward. The axis points to the right. The right pectoral fin coordinate system has the starting point of the right pectoral fin as the origin of coordinates. The axis points forward. The axis points upward. The axis points to the right.

[0008] Preferably, the expression of the kinematic equation of the pectoral fin is:

[0009] In the formula, is the angle between the th microelement strip of the pectoral fin and the plane in the corresponding pectoral fin coordinate system; is the amplitude of the pectoral fin movement; is the angular velocity of the motor in the pectoral fin ; is the time; is the phase difference of the pectoral fin ; is the length of the pectoral fin; is the position of the end point of the th microelement strip of the pectoral fin in the corresponding pectoral fin coordinate system; is the position of the end point of the is the component of the position of the end point of the th micro-element strip of the pectoral fin on the axis of the corresponding pectoral fin coordinate system; is the component of the position of the end point of the th micro-element strip of the pectoral fin on the axis of the corresponding pectoral fin coordinate system; is the component of the position of the end point of the th micro-element strip of the pectoral fin on the axis of the corresponding pectoral fin coordinate system; is the width of the th micro-element strip, taking ( , ), taking indicates the right pectoral fin; taking indicates the left pectoral fin.

[0010] Preferably, the width expression of the micro-element is:

[0011] wherein, is the th micro-element strip of the pectoral fin; is the length of the pectoral fin.

[0012] Preferably, the expression of the force generated by the micro-element strip of the pectoral fin is:

[0013] wherein, is the force generated by the th micro-element strip of the pectoral fin; is the density of water; is the th micro-element strip of the pectoral fin; is the th velocity of the micro-element strip of the pectoral fin; is the thrust coefficient of the pectoral fin ; is the th normal velocity of the center point of the micro-element strip of the pectoral fin; , is the th tangential velocity of the center point of the micro-element strip of the pectoral fin, is the th The moment arm from the starting point of a differential strip to the center point; Take ( , ), Take When it represents the right pectoral fin; Take When it represents the left pectoral fin.

[0014] Preferably, the expression of the moment arm from the starting point of the differential strip to the center point is:

[0015] In the formula, is the position of the end point of the th differential strip of the pectoral fin in the corresponding pectoral fin coordinate system.

[0016] Preferably, the expressions of the target force and target moment of the pectoral fin in the vehicle coordinate system are:

[0017] In the formula, is the target force obtained by converting the force generated by the pectoral fin to the vehicle coordinate system; is the target moment obtained by converting the moment generated by the pectoral fin to the vehicle coordinate system; is the transformation matrix from the corresponding pectoral fin coordinate system of the pectoral fin to the vehicle coordinate system; is the length of the pectoral fin; is the moment arm length of the force that generates a moment after the force generated by the pectoral fin is converted to the vehicle coordinate system; Take ( , ), Take When it represents the right pectoral fin; Take When it represents the left pectoral fin.

[0018] Preferably, the steps to establish the dynamic model of the robotic fish prototype are: According to the total force and total moment of the robotic fish, construct a vector composed of the total force and total moment of the robotic fish; Based on the vector composed of the total force and total moment of the robotic fish, and use the Fossen equation to establish the dynamic model of the robotic fish prototype; Among them, the expression of the vector composed of the total force and total moment of the robotic fish is:

[0019] In the formula, is the vector composed of the total force and total moment of the robotic fish; is the target force obtained by converting the force generated by the right pectoral fin of the robotic fish into the vehicle coordinate system; is the target force obtained by converting the force generated by the left pectoral fin of the robotic fish into the vehicle coordinate system; is the target moment obtained by converting the moment generated by the right pectoral fin of the robotic fish into the vehicle coordinate system; is the target moment obtained by converting the moment generated by the left pectoral fin of the robotic fish into the vehicle coordinate system.

[0020] Preferably, the expression of the dynamic model of the robotic fish prototype is:

[0021] In the formula, represents the vector composed of the position and attitude of the robotic fish in the vehicle coordinate system; represents the vector composed of the velocity and angular velocity of the robotic fish in the earth coordinate system; represents the transformation matrix from the vehicle coordinate system to the earth coordinate system; represents the inertia matrix; is the Coriolis and centripetal matrix; represents the hydrodynamic damping matrix, is the vector composed of the restoring force and restoring moment; is the vector composed of the total force and total moment of the robotic fish.

[0022] The technical solution adopted by a dynamic modeling system of a robotic fish with distributed drive pectoral fins includes: A coordinate system construction module for establishing a ground coordinate system, a vehicle coordinate system, a left pectoral fin coordinate system, and a right pectoral fin coordinate system; A kinematic equation construction module for establishing the kinematic equations of the corresponding pectoral fins in the left pectoral fin coordinate system and the right pectoral fin coordinate system respectively based on the method of dividing micro-element strips; obtaining the positions of the end points of each micro-element strip by using the kinematic equations; A parameter acquisition module for obtaining the forces generated by the micro-element strips of the corresponding pectoral fins in the left pectoral fin coordinate system and the right pectoral fin coordinate system by using the Morison equation, and obtaining the forces and moments generated by each pectoral fin based on the forces generated by the micro-element strips; converting the forces and moments generated by each pectoral fin to the vehicle coordinate system to obtain the target forces and target moments of each pectoral fin in the vehicle coordinate system; obtaining the total force and total moment of the robotic fish according to the target forces and target moments of the two pectoral fins; And a dynamic model construction module for establishing a dynamic model of the robotic fish prototype according to the total force and total moment of the robotic fish by using the Fossen equation; wherein, the dynamic model is used to input the velocity and angular velocity of the robotic fish in the vehicle coordinate system to output the position and attitude of the robotic fish in the earth coordinate system The beneficial effects of the present invention are as follows: Compared with the prior art, the method of the present invention is universal, that is, it can be applied to all bionic underwater robots with the same type of distributed drive pectoral fins; the method of the present invention has a certain adaptability to the structure of the distributed drive pectoral fins, that is, when the shape of the pectoral fin or the number of distributed drive motors changes, this method is still applicable; the dynamic model given by the present invention can predict the motion state of the entire robotic fish according to the input motor angular velocity, that is, the dynamic model of the present invention can be used for the simulation verification of the controller of the robotic fish, providing a new research idea for the subsequent in-depth study of the motion control of the robotic fish with distributed drive pectoral fins. Description of the Drawings

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0024] Figure 1 It is a flow chart of a dynamic modeling method for a robotic fish with distributed drive pectoral fins according to the present invention; Figure 2 It is a schematic diagram of the coordinate system constructed in the embodiment of the present invention; Figure 3 It is a schematic diagram of the pectoral fin structure of the bionic robotic fish according to the present invention; Figure 4 It is a schematic diagram of the calculation principle of the force generated by the pectoral fin of the bionic robotic fish in the embodiment of the present invention; Figure 5 It is a velocity curve diagram of the dynamic model simulation output of the bionic robotic fish prototype in the embodiment of the present invention; Figure 6 It is an attitude angle curve diagram of the dynamic model simulation output of the bionic robotic fish prototype in the embodiment of the present invention. Detailed Embodiment

[0025] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0026] An embodiment of a dynamic modeling method for a robotic fish with distributed drive pectoral fins according to the present invention is as Figure 1 shown and includes: S1. Construct a coordinate system; In an exemplary embodiment, as Figure 2 shown, four coordinate systems are established, namely the ground coordinate system {G}, the carrier coordinate system {B}, the left pectoral fin coordinate system {L}, and the right pectoral fin coordinate system {R}. Among them, when establishing the ground coordinate system, the center of the pool where the robotic fish is located is taken as the origin. Each axis of this coordinate system is fixedly connected to the earth (stationary relative to the ground). The axis points to the due north direction. The positive direction of the axis is vertically upward. The axis points to the due east direction. The carrier coordinate system takes the center of buoyancy of the robotic fish as the coordinate origin. Each axis of this coordinate system is fixedly connected to the robotic fish (stationary relative to the robotic fish). The axis points to the head of the robotic fish. The axis points upward. The axis points to the right side of the robotic fish. The left pectoral fin coordinate system uses the starting point of the left pectoral fin as the coordinate origin. The axis points forward. The axis points upward. The axis points to the right. The right pectoral fin coordinate system uses the starting point of the right pectoral fin as the coordinate origin. The axis points forward. The axis points upward. The axis points to the right.

[0027] S2. Construct the kinematic equations of the pectoral fins; According to Figure 3 the principle of the distributed drive pectoral fin mechanism of the bionic robotic fish shown, based on the method of dividing into microelement strips, the corresponding kinematic equations of the pectoral fins are established in the left pectoral fin coordinate system and the right pectoral fin coordinate system respectively, and the positions of the end points of each microelement strip are obtained by using the kinematic equations.

[0028] Among them, the expression of the kinematic equation of the pectoral fin is:

[0029] In the formula, is the angle between the th microelement strip of the pectoral fin and the plane in the corresponding pectoral fin coordinate system; ; is the amplitude of the movement of the pectoral fin ; is the angular velocity of the motor in the pectoral fin ; is the time; is the phase difference of the pectoral fin ; is the length of the pectoral fin; is the th in the corresponding pectoral fin coordinate system of the pectoral fin The position of the end point of a micro-element strip is the pectoral fin of the th micro-element strip, and the component of the position of the end point of the th micro-element strip on the axis in the corresponding pectoral fin coordinate system; is the pectoral fin of the th micro-element strip, and the component of the position of the end point of the th micro-element strip on the axis in the corresponding pectoral fin coordinate system; is the pectoral fin of the th micro-element strip, and the component of the position of the end point of the th micro-element strip on the axis in the corresponding pectoral fin coordinate system; is the width of the th micro-element strip, taking ( , ), taking indicates the right pectoral fin; taking indicates the left pectoral fin.

[0030] As shown in Figure 4 , taking the right pectoral fin as an example, the right pectoral fin is divided into micro-element strips. In this embodiment, is taken. The kinematic equation of the right pectoral fin is established in the right pectoral fin coordinate system {R}. The kinematic equation of the right pectoral fin is:

[0031] In the formula, is the angle between the th micro-element strip of the right pectoral fin in the right pectoral fin coordinate system {R} and the plane ; is the amplitude of the movement of the right pectoral fin ; is the angular velocity of the motor in the right pectoral fin ; is the angular velocity of the motor in the right pectoral fin is the time; is the phase difference of the right pectoral fin ; is the length of the right pectoral fin; in this case °, ° / s, °, ; is the th of the right pectoral fin in the right pectoral fin coordinate system {R} The position of the end point of the microelement strip, Right pectoral fin No. The position of the end point of the microelement strip is in the corresponding right pectoral fin coordinate system {R} Components on the axis; Right pectoral fin No. The position of the end point of each microelement in the corresponding pectoral fin coordinate system Components on the axis; Right pectoral fin No. The position of the end point of the microelement strip is in the corresponding right pectoral fin coordinate system {R} Components on the axis; For the The width of the microelement strip.

[0032] In this embodiment, the width of the microelement strip is expressed as follows:

[0033] In the formula, The pectoral fin microelement strip; is the length of the pectoral fin.

[0034] At this point, the kinematic equation can be used to obtain the position of the end point of each microelement strip.

[0035] S3, obtaining the total force and total torque of the robotic fish; In an exemplary embodiment, the steps of obtaining the total force and total torque of the robot fish are as follows: S31, based on the method of dividing the microelement strips, in the left pectoral fin coordinate system and the right pectoral fin coordinate system, respectively, the force generated by the microelement strip of the corresponding pectoral fin is obtained using the Morison equation; S32, based on the force generated by the microelement strip, the force and torque generated by each pectoral fin is obtained, and the force and torque generated by each pectoral fin is converted to the carrier coordinate system to obtain the target force and target torque of each pectoral fin in the carrier coordinate system; the total force and total torque of the robot fish are obtained according to the target forces and target torques of the two pectoral fins.

[0036] Exemplarily, in step S31, the step of using the Morison equation to obtain the force generated by the microelement strip of the corresponding pectoral fin is: Step S311: Calculate the force generated by the microelement strip of the right pectoral fin in the right pectoral fin coordinate system {R} based on the Morison equation, that is, the expression of the force generated by the microelement strip of the right pectoral fin is:

[0037] in, Right pectoral fin The force generated by the th micro-element strip; is the density of water, ; is the velocity of the th micro-element strip of the right pectoral fin; is the thrust coefficient of the right pectoral fin; is the normal velocity of the center point of the th micro-element strip of the right pectoral fin; ; is the tangential velocity of the center point of the th micro-element strip of the right pectoral fin; is the moment arm from the starting point to the center point of the th micro-element strip of the right pectoral fin.

[0038] Among them, the expression of the moment arm from the starting point to the center point of the micro-element strip of the right pectoral fin is:

[0039] In the formula, is the position of the end point of the th micro-element strip of the right pectoral fin in the corresponding pectoral fin coordinate system.

[0040] Step S312: Calculate the force generated by the micro-element strip of the left pectoral fin in the left pectoral fin coordinate system {L} based on the Morison equation. That is, the expression of the force generated by the micro-element strip of the left pectoral fin is:

[0041] Among them, is the force generated by the th micro-element strip of the left pectoral fin; is the density of water, ; is the velocity of the th micro-element strip of the left pectoral fin; is the thrust coefficient of the left pectoral fin; is the normal velocity of the center point of the th micro-element strip of the left pectoral fin; ; is the tangential velocity of the center point of the th micro-element strip of the left pectoral fin; is the left pectoral fin​​​​​​​​​​​ The moment arm from the starting point of the th infinitesimal strip of the left pectoral fin to the center point.

[0042] Among them, the left pectoral fin The expression of the moment arm from the starting point of the infinitesimal strip to the center point is:

[0043] In the formula, is the position of the end point of the th infinitesimal strip of the left pectoral fin in the corresponding pectoral fin coordinate system.

[0044] Exemplarily, in step S32, the forces and torques generated by each pectoral fin are obtained based on the forces generated by the infinitesimal strips.

[0045] Among them, the expressions of the target force and target torque of the pectoral fin in the vehicle coordinate system are:

[0046] In the formula, is the target force obtained by converting the force generated by the pectoral fin to the vehicle coordinate system; is the target torque obtained by converting the torque generated by the pectoral fin to the vehicle coordinate system; is the transformation matrix from the corresponding pectoral fin coordinate system of the pectoral fin to the vehicle coordinate system; is the length of the pectoral fin; is the moment arm length for generating torque when the force generated by the pectoral fin is converted to the vehicle coordinate system; Take ( , ), Take when it represents the right pectoral fin; Take when it represents the left pectoral fin Exemplarily, taking the right pectoral fin as an example: S321. Calculate the force generated by the right pectoral fin in the right pectoral fin coordinate system {R}, and then convert the force generated by the right pectoral fin to the vehicle coordinate system {B} through the transformation matrix, that is, obtain the target force and target torque of the right pectoral fin in the right pectoral fin coordinate system {R}. The expressions of the target force and target torque of the right pectoral fin in the right pectoral fin coordinate system {R} are:

[0047] In the formula, is the target force obtained by converting the force generated by the right pectoral fin to the vehicle coordinate system; is the target force obtained by converting the force generated by the right pectoral fin The generated torque is converted to the target torque in the body coordinate system {B}; is the transformation matrix from the right pectoral fin coordinate system {R} to the body coordinate system {B}; is the length of the pectoral fin; is the right pectoral fin The length of the lever arm for the force generated by the right pectoral fin to generate torque after being converted to the body coordinate system.

[0048] Exemplarily, taking the left pectoral fin as an example: S321. Calculate the force generated by the left pectoral fin in the left pectoral fin coordinate system {L}, and then convert the force generated by the left pectoral fin to the body coordinate system {B} through the transformation matrix, that is, obtain the target force and target torque of the left pectoral fin in the left pectoral fin coordinate system {L}. The expressions for the target force and target torque of the left pectoral fin in the left pectoral fin coordinate system {L} are:

[0049] In the formula, is the left pectoral fin The target force for the force generated by the left pectoral fin after being converted to the body coordinate system; is the left pectoral fin The target torque for the torque generated by the left pectoral fin after being converted to the body coordinate system {B}; is the transformation matrix from the left pectoral fin coordinate system {L} to the body coordinate system {B}; is the length of the pectoral fin; is the left pectoral fin The length of the lever arm for the force generated by the left pectoral fin to generate torque after being converted to the body coordinate system.

[0050] Exemplarily, step 33. The steps to obtain the total force and total torque of the robotic fish according to the target forces and target torques of the two pectoral fins are: The sum of the target force of the force generated by the right pectoral fin of the robotic fish after being converted to the body coordinate system and the target force of the force generated by the left pectoral fin of the robotic fish after being converted to the body coordinate system is used as the total force of the robotic fish, that is, the total force is ; The sum of the target torque of the torque generated by the right pectoral fin of the robotic fish after being converted to the body coordinate system and the target torque of the torque generated by the left pectoral fin of the robotic fish after being converted to the body coordinate system is used as the total torque of the robotic fish, that is, the total torque is .

[0051] S4. Establish the dynamic model of the robotic fish prototype; Specifically, according to the total force and total torque of the robotic fish, and using the Fossen equation to establish the dynamic model of the robotic fish prototype; among them, the dynamic model is used to input the velocity and angular velocity of the robotic fish in the body coordinate system to output the position and attitude of the robotic fish in the earth coordinate system.

[0052] Among them, in an exemplary embodiment, the steps of establishing the dynamic model of the robotic fish prototype using the Fossen equation are as follows: According to the total force and total moment of the robotic fish, construct a vector composed of the total force and total moment of the robotic fish; Based on the vector composed of the total force and total moment of the robotic fish, and use the Fossen equation to establish the dynamic model of the robotic fish prototype.

[0053] Exemplarily, the expression of the vector composed of the total force and total moment of the robotic fish is:

[0054] In the formula, is the vector composed of the total force and total moment of the robotic fish; is the target force obtained by converting the force generated by the right pectoral fin of the robotic fish into the vehicle coordinate system; is the target force obtained by converting the force generated by the left pectoral fin of the robotic fish into the vehicle coordinate system; is the target moment obtained by converting the moment generated by the right pectoral fin of the robotic fish into the vehicle coordinate system; is the target moment obtained by converting the moment generated by the left pectoral fin of the robotic fish into the vehicle coordinate system.

[0055] Exemplarily, the expression of the dynamic model of the robotic fish prototype is:

[0056] In the formula, represents the vector composed of the position and attitude of the robotic fish in the vehicle coordinate system; represents the vector composed of the velocity and angular velocity of the robotic fish in the earth coordinate system; represents the transformation matrix from the vehicle coordinate system to the earth coordinate system; represents the inertia matrix of; is the Coriolis and centripetal matrix; represents the vector composed of the hydrodynamic damping matrix, is the restoring force and restoring moment; is the vector composed of the total force and total moment of the robotic fish.

[0057] A dynamic modeling system for a robotic fish with distributed-driven pectoral fins, comprising: a coordinate system construction module, a kinematic equation construction module, a parameter acquisition module, and a dynamic model construction module. The coordinate system construction module is used to establish a ground coordinate system, a vehicle coordinate system, a left pectoral fin coordinate system, and a right pectoral fin coordinate system. The kinematic equation construction module is used to establish the kinematic equations of the corresponding pectoral fins in the left pectoral fin coordinate system and the right pectoral fin coordinate system respectively based on the method of dividing into micro-element strips, and obtain the positions of the end points of each micro-element strip by using the kinematic equations. The parameter acquisition module is used to obtain the forces generated by the micro-element strips of the corresponding pectoral fins in the left pectoral fin coordinate system and the right pectoral fin coordinate system by using the Morison equation, and obtain the forces and torques generated by each pectoral fin based on the forces generated by the micro-element strips. Convert the forces and torques generated by each pectoral fin to the vehicle coordinate system to obtain the target forces and target torques of each pectoral fin in the vehicle coordinate system. Obtain the total force and total torque of the robotic fish according to the target forces and target torques of the two pectoral fins. The dynamic model construction module is used to establish the dynamic model of the robotic fish prototype according to the total force and total torque of the robotic fish by using the Fossen equation. Wherein, the dynamic model is used to input the velocity and angular velocity of the robotic fish in the vehicle coordinate system to output the position and attitude of the robotic fish in the earth coordinate system.

[0058] The present invention will be specifically described below with reference to the accompanying drawings: Use the established dynamic model of the robotic fish prototype to conduct a simulation experiment. The velocity information output by the dynamic model of the robotic fish prototype is as Figure 5 shown, and the attitude angle information output by the dynamic model of the robotic fish prototype is as Figure 6 shown. Figure 5 It reflects that the established model has the ability to simulate and correctly output the velocities in the x, y, and z axes. Figure 6 It reflects that the established model has the ability to simulate and correctly output the attitude angles around the x, y, and z axes.

[0059] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for dynamic modeling of a robotic fish with distributed driven pectoral fins, characterized in that: include: Establish a ground coordinate system, a carrier coordinate system, a left pectoral fin coordinate system, and a right pectoral fin coordinate system; Based on the method of dividing microelement strips, the kinematic equations of the corresponding pectoral fins are established in the left pectoral fin coordinate system and the right pectoral fin coordinate system respectively; the kinematic equations are used to obtain the position of the end point of each microelement strip; In the left pectoral fin coordinate system and the right pectoral fin coordinate system, the force generated by the microelement strip of the corresponding pectoral fin is obtained by using the Morison equation, and the force and torque generated by each pectoral fin are obtained based on the force generated by the microelement strip; The force and torque generated by each pectoral fin are converted into the carrier coordinate system to obtain the target force and target torque of each pectoral fin in the carrier coordinate system; The total force and total moment of the robotic fish are obtained according to the target force and target moment of the two pectoral fins; According to the total force and total torque of the robotic fish, the dynamic model of the robotic fish prototype is established using the Fossen equation; the dynamic model is used to input the velocity and angular velocity of the robotic fish in the carrier coordinate system to output the position and posture of the robotic fish in the earth coordinate system.

2. The method for dynamic modeling of a robotic fish with distributed drive pectoral fins according to claim 1, characterized in that: The steps to establish the ground coordinate system, the carrier coordinate system, the left pectoral fin coordinate system, and the right pectoral fin coordinate system are as follows: The axes of the ground coordinate system are fixed to the earth, and the origin of the ground coordinate system is selected somewhere on the ground. The axis points due north. The positive direction of the axis is vertically upward. The axis points due east; Each axis of the carrier coordinate system is fixedly connected to the robot fish, and the center of buoyancy is used as the coordinate origin. The axis points to the head of the robot fish. The axis points upward. The axis points to the right side of the robotic fish; The left pectoral fin coordinate system takes the starting point of the left pectoral fin as the coordinate origin. The axis points forward. The axis points upward. The axis points to the right; The right pectoral fin coordinate system takes the starting point of the right pectoral fin as the coordinate origin. The axis points forward. The axis points upward. The axis points to the right.

3. The method for dynamic modeling of a robotic fish with distributed drive pectoral fins according to claim 1, characterized in that: The kinematic equation of the pectoral fin is: In the formula, For pectoral fin In the corresponding pectoral fin coordinate system Microelement strip and plane The angle of For pectoral fin Amplitude of movement; For pectoral fin Angular velocity of the motor; for the moment; For pectoral fin The phase difference; is the length of the pectoral fin; For pectoral fin In the corresponding pectoral fin coordinate system The location of the end point of each microelement strip; For pectoral fin No. The position of the end point of the microelement strip is in the corresponding pectoral fin coordinate system Components on the axis; For pectoral fin No. The position of the end point of the microelement strip is in the corresponding pectoral fin coordinate system Components on the axis; For pectoral fin No. The position of the end point of the microelement strip is in the corresponding pectoral fin coordinate system Components on the axis; For the The width of the microelement strip, Pick( , ), Pick : indicates the right pectoral fin; Pick : indicates the left pectoral fin.

4. The method for dynamic modeling of a robotic fish with distributed drive pectoral fins according to claim 3, characterized in that: The width of the microelement strip is expressed as: In the formula, The pectoral fin microelement strip; is the length of the pectoral fin.

5. The method for dynamic modeling of a robotic fish with distributed drive pectoral fins according to claim 1, characterized in that: The force generated by the microelement strip of the pectoral fin is expressed as: In the formula, For pectoral fin No. The force generated by each microelement strip; is the density of water; For pectoral fin No. The speed of the microelement strip; For pectoral fin The thrust coefficient of For pectoral fin No. The normal velocity of the center point of each microelement strip; , For pectoral fin No. The tangential velocity of the center point of the microelement strip is For pectoral fin No. The arm of force from the starting point to the center point of the microelement strip; Pick( , ), Pick : indicates the right pectoral fin; Pick : indicates the left pectoral fin.

6. The method for dynamic modeling of a robotic fish with distributed drive pectoral fins according to claim 5, characterized in that: The expression of the force arm from the starting point to the center point of the infinitesimal strip is: In the formula, For pectoral fin In the corresponding pectoral fin coordinate system The location of the end point of the microelement strip.

7. The method for dynamic modeling of a robotic fish with distributed drive pectoral fins according to claim 1, characterized in that: The expressions of the target force and target moment of the pectoral fin in the carrier coordinate system are: In the formula, For pectoral fin The generated force is converted into the target force in the carrier coordinate system; For pectoral fin The generated torque is converted into the target torque in the carrier coordinate system; For pectoral fin The corresponding transformation matrix from the pectoral fin coordinate system to the carrier coordinate system; is the length of the pectoral fin; For pectoral fin The generated force is converted to the length of the arm that generates the torque in the carrier coordinate system; Pick( , ), Pick : indicates the right pectoral fin; Pick : indicates the left pectoral fin.

8. The method for dynamic modeling of a robotic fish with distributed drive pectoral fins according to claim 1, characterized in that: The steps to build the dynamic model of the robotic fish prototype are: According to the total force and total torque of the robot fish, construct the vector of the total force and total torque of the robot fish; Based on the vectors of the total force and total torque of the robotic fish, the dynamic model of the robotic fish prototype is established using the Fossen equation; Among them, the expression of the vector composed of the total force and total torque of the robot fish is: In the formula, is the vector formed by the total force and total torque of the robot fish; Convert the force generated by the right pectoral fin of the robotic fish into the target force in the carrier coordinate system; Convert the force generated by the left pectoral fin of the robotic fish into the target force in the carrier coordinate system; Convert the torque generated by the right pectoral fin of the robotic fish into the target torque in the carrier coordinate system; The torque generated by the left pectoral fin of the robotic fish is converted into the target torque in the carrier coordinate system.

9. The method for dynamic modeling of a robotic fish with distributed drive pectoral fins according to claim 8, characterized in that: The expression of the dynamic model of the robotic fish prototype is: In the formula, The vector representing the position and posture of the robot fish in the carrier coordinate system; Represents the vector consisting of the velocity and angular velocity of the robot fish in the geodetic coordinate system; Represents the transformation matrix from the carrier coordinate system to the earth coordinate system; The inertia matrix represented by are the Coriolis and centripetal matrices; represents the fluid dynamic damping matrix, is the vector of restoring force and restoring moment; is the vector formed by the total force and total torque of the robot fish.

10. A dynamic modeling system for a robotic fish with distributed drive pectoral fins, characterized in that: include: A coordinate system building module, used to establish a ground coordinate system, a carrier coordinate system, a left pectoral fin coordinate system, and a right pectoral fin coordinate system; The kinematic equation building module is used to establish the kinematic equations of the corresponding pectoral fins in the left pectoral fin coordinate system and the right pectoral fin coordinate system based on the method of dividing the microelement strips; the kinematic equation is used to obtain the position of the end point of each microelement strip; A parameter acquisition module is used to obtain the force generated by the microelement strip of the corresponding pectoral fin in the left pectoral fin coordinate system and the right pectoral fin coordinate system by using the Morison equation, and obtain the force and torque generated by each pectoral fin based on the force generated by the microelement strip; The force and torque generated by each pectoral fin are converted into the carrier coordinate system to obtain the target force and target torque of each pectoral fin in the carrier coordinate system; The total force and total moment of the robotic fish are obtained according to the target force and target moment of the two pectoral fins; And a dynamic model building module, which is used to establish the dynamic model of the robotic fish prototype according to the total force and total torque of the robotic fish and use the Fossen equation; among which, the dynamic model is used to input the velocity and angular velocity of the robotic fish in the carrier coordinate system to output the position and posture of the robotic fish in the earth coordinate system.

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