Small unmanned surface vehicle based on momentum wheel steering structure and steering method

Abstract

The present application relates to the technical field of small unmanned ship, in particular to a small unmanned ship with a steering structure based on momentum wheel and a steering method, which is provided with a hull, the middle part of the hull is fixedly connected with a steering box, a steering structure is installed in the steering box, the steering structure comprises a motor, a flywheel, a control system, an energy storage capacitor group, the control system comprises a main control unit, a posture sensing unit, a motor control unit and a power management unit, the posture sensing unit comprises an accelerometer, an electronic compass, a gyroscope and a data solving module, the steering method of the small unmanned ship with the steering structure based on momentum wheel has the advantages of simple structure, convenient maintenance, strong steering capacity, high steering precision, high reliability and the ability to realize steering in a low speed or even static state.

Description

Technical Field

[0001] This invention relates to the field of small unmanned surface vessel (USV) technology, specifically a small USV with a steering structure based on a momentum wheel and a steering method thereof. Background Technology

[0002] As is well known, existing steering methods for small unmanned surface vessels mainly include rudder steering, rotary propulsion, and differential steering. These steering methods generally suffer from the following problems: 1. Steering mechanisms are mostly external structures, and being submerged in water for extended periods, they are susceptible to corrosion; 2. Exposed structures are prone to entanglement with aquatic plants or foreign objects, affecting their reliability. 3. The mechanical structure is complex, resulting in high maintenance and replacement costs; 4. Poor steering ability at low speeds or when stationary; 5. Limited steering precision, making precise control difficult; 6. Lack of effective redundant steering mechanisms.

[0003] Therefore, it is necessary to provide a small unmanned surface vessel that is simple in structure, built-in, easy to maintain, and capable of turning at low speeds or even when stationary. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a small unmanned surface vessel and steering method based on a momentum wheel steering structure that is simple in structure, easy to maintain, has strong steering ability, high steering accuracy, high reliability, and can achieve steering at low speeds or even when stationary.

[0005] The technical solution adopted by this invention to solve its technical problem is: A small unmanned surface vessel (USV) with a momentum wheel-based steering structure is provided. The USV has a hull, characterized in that a steering housing is fixedly connected to the middle of the hull. The steering housing houses the steering structure, which includes a motor, a flywheel, a control system, and an energy storage capacitor bank. The motor is fixed to the bottom of the steering housing, with its output shaft facing upwards and connected to the center of the flywheel. The control system includes a main control unit, an attitude sensing unit, a motor control unit, and a power management unit. The attitude sensing unit includes an accelerometer, an electronic compass, a gyroscope, and a data processing module. The accelerometer, electronic compass, and gyroscope are connected to the data processing module, which is connected to the main control unit. The main control unit is connected to both the motor control unit and the power management unit. The motor control unit is connected to the motor, and the power management unit is connected to the motor control unit, the motor, and the energy storage capacitor bank.

[0006] The center of the flywheel described in this invention lies on the straight line where the center of mass of the hull is located.

[0007] The present invention describes a propeller installed at the bottom of the hull, a drive motor installed inside the hull, and the output end of the drive motor connected to the propeller.

[0008] The flywheel of the present invention includes a rim portion and a spoke portion. The rim portion is annular and its thickness is greater than that of the spoke portion. The rim portion is fitted around the outside of the spoke portion and is integrally connected to the spoke portion. A central shaft hole is provided at the center of the spoke portion and is connected to the output shaft of the motor.

[0009] A steering method for a small unmanned surface vessel based on a momentum wheel steering structure, characterized by the following steps: (1) Obtain parameters: ship length, width, weight, ship moment of inertia, flywheel diameter, weight, flywheel moment of inertia Jw, motor back electromotive force constant Ke, torque constant Kt, armature resistance Ra, total circuit resistance R of generator circuit, ship main power supply voltage. (2) Define the directions of the angular velocity and angular acceleration of the flywheel, motor, and hull, with clockwise as positive and counterclockwise as negative from the top viewpoint; (3) Obtain the target heading angle and the real-time speed of the ship to obtain the target angular velocity of the hull; (4) Obtain the target angular acceleration of the flywheel based on the target angular velocity; (5) Calculate the target torque output by the motor based on the target angular acceleration of the flywheel; (6) Obtain the current motor direction and speed: If the motor's rotation direction is the same as the flywheel's target angular acceleration direction, then the motor enters acceleration mode, controlling its acceleration. The duty cycle for controlling motor acceleration is then determined. , If the motor's rotation direction is opposite to the flywheel's target angular velocity direction, the motor enters deceleration mode. The deceleration power is calculated, and based on the maximum charging power and the deceleration power, the percentage of time the motor is connected to the capacitor for charging is calculated. ; (7) The final output signal controls the motor: In acceleration mode: the main control unit output duty cycle is The PWM waveform controls the motor's output torque, and the motor can automatically output the specified power according to the PWM waveform requirements. In deceleration mode: The main control unit outputs a command to instruct the power management unit to connect the positive and negative terminals of the motor to the capacitor bank, with a duty cycle of [duty cycle missing]. , (8) Loop calculation: After outputting the control signal, loop to step (3) - step (7) to repeat the whole process; each loop changes various data dynamically, and the algorithm also dynamically adjusts the output torque and motor output power accordingly.

[0010] In step (3) of the present invention, the specific steps are: reading the values ​​of the accelerometer, electronic compass and gyroscope in the attitude sensing unit and obtaining the current heading angle and real-time speed through the data calculation module; According to the formula Obtain the target angular velocity of the ship; Kp: Proportional gain, related to the ship's real-time speed; taken as 0.3s^ when the sailing speed is below 2m / s. -1 For speeds above 2 m / s, take 0.1 s^2. -1 Target heading angle Unit: deg; Current heading angle θ; Unit: deg; Target angular velocity of the ship. ,unit .

[0011] In step (4) of the present invention, the specific steps are as follows: according to the following formula; ; in: Angular velocity control gain, in seconds (s^-1), is the ratio of the moment of inertia of the hull to that of the flywheel. This ratio is the ratio of their angular accelerations. Multiplying this ratio by 1 / 4 yields the result. The direction of the wheel's angular acceleration is opposite to that of the hull. Take a negative number; the direction of the wheel angular acceleration is the same as that of the hull. Take positive numbers. For target angular acceleration, in units Real-time angular velocity The unit is .

[0012] In step (5) of the present invention, the specific steps are as follows: according to the following formula; ; in: Target angular acceleration of the flywheel, in units , The moment of inertia of the flywheel, in units of , This represents the torque that the motor needs to output, in units of... .

[0013] In step (6) of this invention, the duty cycle for controlling the acceleration of the motor is: The specific calculation steps are as follows: Based on the relationship between voltage and rotational speed: Relationship between torque and current: It can be deduced that the duty cycle for controlling the acceleration of the motor is... , Where V is the armature voltage, measured in volts (V), which is the supply voltage multiplied by the duty cycle. ; η is the power supply voltage, in volts (V); n is the angular velocity of the motor, in cubic meters (Ω). I represents the motor current, in units of... , Armature resistance, unit: , Motor torque, unit: , The value is , The torque constant is expressed in units of 1000 ppm. , The back electromotive force constant of the motor is given by . .

[0014] In step (6) of this invention, the method for calculating the deceleration power P is as follows: The calculation method for the maximum charging power Pm is as follows: Based on the current speed and capacitor voltage, the maximum charging power when the motor is connected across the energy storage capacitor bank is obtained. Where Vcap is the voltage across the capacitor, in volts (V), obtained from the power management module; the motor generator voltage is... n is the angular velocity of the motor, and the unit is angular velocity. , The back electromotive force constant of the motor is given by . The total resistance R of the power generation circuit is measured in units of... The calculation method for the percentage of time n2 that the motor spends charging the capacitor is as follows: P represents the reduction power, measured in watts (W). This represents the maximum charging power, measured in watts (W).

[0015] Because of the above-mentioned structure, this invention has the advantages of simple structure, convenient maintenance, strong steering ability, high steering accuracy, high reliability, and the ability to achieve steering at low speeds or even when stationary. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of the present invention.

[0017] Figure 2 This is the system control relationship diagram of the present invention.

[0018] Figure 3 This is a schematic diagram of the flywheel structure.

[0019] Reference numerals: 1. Hull; 2. Steering box; 3. Motor; 4. Flywheel; 401. Wheel rim; 402. Spoke; 403. Central shaft hole; 5. Control system; 6. Energy storage capacitor bank. Detailed Implementation

[0020] The present invention will be further described below with reference to the accompanying drawings: As shown in the attached figure, a small unmanned surface vessel (USV) with a momentum wheel-based steering structure includes a hull 1. The hull 1 is characterized by a steering housing 2 fixedly connected to its center. The steering housing 2 houses the steering structure, which includes a motor 3, a flywheel 4, a control system 5, and an energy storage capacitor bank 6. The motor 3 is fixed to the bottom of the steering housing 2, with its output shaft facing upwards and connected to the center of the flywheel 4. The control system 5 includes a main control unit, an attitude sensing unit, a motor control unit, and a power management unit. The attitude sensing unit includes an accelerometer, an electronic compass, a gyroscope, and a data processing module. The accelerometer, electronic compass, and gyroscope are connected to the data processing module, which is connected to the main control unit. The main control unit is connected to both the motor control unit and the power management unit. The motor control unit is connected to the motor 3, and the power management unit is connected to the motor control unit, the motor 3, and the energy storage capacitor bank 6.

[0021] Furthermore, the center of the flywheel 4 is on the straight line where the center of mass of the hull 1 is located.

[0022] Furthermore, a propeller is installed at the bottom of the hull 1, and a drive motor is installed inside the hull 1, with the output end of the drive motor connected to the propeller.

[0023] Furthermore, the flywheel 4 includes a rim portion 401 and a spoke portion 402. The rim portion 401 is annular, and the thickness of the rim portion 401 is greater than the thickness of the spoke portion 402. The rim portion 401 is fitted onto the outside of the spoke portion 402 and is integrally connected to the spoke portion 402. A central shaft hole 403 is provided at the center of the spoke portion 402, and the central shaft hole 403 is connected to the output shaft of the motor 3.

[0024] A steering method for a small unmanned surface vessel based on a momentum wheel steering structure, characterized by the following steps: (1) Obtain parameters: the length, width, weight of the ship, the moment of inertia of the ship, the diameter and weight of the flywheel 4, the moment of inertia of the flywheel 4 Jw, the back electromotive force constant Ke of the motor 3, the torque constant Kt, the armature resistance Ra, the total circuit resistance R of the generator circuit, and the main power supply voltage on the ship. (2) Define the directions of the angular velocity and angular acceleration of the flywheel 4, motor 3, and hull, with clockwise as positive and counterclockwise as negative from the top viewpoint; (3) Obtain the target heading angle and the real-time speed of the ship to obtain the target angular velocity of the hull; (4) Obtain the target angular acceleration of flywheel 4 based on the target angular velocity; (5) Calculate the target torque Td output by motor 3 based on the target angular acceleration of flywheel 4; (6) Obtain the current direction and speed of motor 3: If the direction of rotation of motor 3 is the same as the direction of the target angular acceleration of flywheel 4, then motor 3 enters acceleration mode, controlling motor 3 to accelerate. The duty cycle for controlling the acceleration of motor 3 is: , If the direction of motor 3 is opposite to the direction of the target angular velocity of flywheel 4, then motor 3 will enter deceleration mode. The deceleration power will be calculated. Based on the maximum charging power and the deceleration power, the percentage of time that motor 3 is connected to the capacitor for charging can be calculated. ; (7) The final output signal controls motor 3: In acceleration mode: the main control unit output duty cycle is The PWM waveform controls the output torque of motor 3, and motor 3 can automatically output the specified power according to the PWM waveform requirements. In deceleration mode: The main control unit outputs a command to instruct the power management unit to connect the positive and negative terminals of motor 3 to the capacitor bank, with a duty cycle of [duty cycle missing]. , (8) Loop calculation: After outputting the control signal, loop to step (3) - step (7) to repeat the whole process; each loop changes various data dynamically, and the algorithm also dynamically adjusts the output torque and motor 3 output power accordingly.

[0025] Furthermore, in step (5), the specific steps are as follows: according to the following formula; ; in: Target angular acceleration of the flywheel, in units , The moment of inertia of the flywheel, in units of , This represents the torque that the motor needs to output, in units of... .

[0026] Furthermore, in step (6), the duty cycle for controlling the motor acceleration is... The specific calculation steps are as follows: Based on the relationship between voltage and rotational speed: Relationship between torque and current: It can be deduced that the duty cycle for controlling the acceleration of the motor is... , Where V is the armature voltage, measured in volts (V), which is the supply voltage multiplied by the duty cycle. ; η is the power supply voltage, in volts (V); n is the angular velocity of the motor, in cubic meters (Ω). I represents the motor current, in units of... , Armature resistance, unit: , Motor torque, unit: , The value is , The torque constant is expressed in units of 1000 ppm. , The back electromotive force constant of the motor is given by . .

[0027] Furthermore, in step (6), the method for calculating the deceleration power P is as follows: The calculation method for the maximum charging power Pm is as follows: Based on the current speed and capacitor voltage, the maximum charging power when the motor is connected across the energy storage capacitor bank is obtained. Where Vcap is the voltage across the capacitor, in volts (V), obtained from the power management module; the motor generator voltage is... n is the angular velocity of the motor, and the unit is angular velocity. , The back electromotive force constant of the motor is given by . The total resistance R of the power generation circuit is measured in units of... The calculation method for the percentage of time n2 that the motor spends charging the capacitor is as follows: P represents the reduction power, measured in watts (W). This represents the maximum charging power, measured in watts (W).

[0028] Because of the above-mentioned structure, this invention has the advantages of simple structure, convenient maintenance, strong steering ability, high steering accuracy, high reliability, and the ability to achieve steering at low speeds or even when stationary.

[0029] Example (1) Obtaining parameters: Ship parameters: Length L = 5m, Width B = 1.5m, Total weight approximately 500kg, Center of mass located on the intersection of the midship plane and the centerline plane, Moment of inertia about the intersection of the midship plane and the centerline plane (i.e., the central axis). The moment of inertia is 1216 kg•m^2 (the hull's moment of inertia can be directly obtained from the ship's design software). For an iron flywheel 4 with a thick rim and thin spokes, and a mass of 20.03 kg, the moment of inertia is... for , Flywheel parameters: The structural parameters of the flywheel are shown in Table 1 below: Table 1: Structural parameters of the flywheel outer diameter of rim 0.3 m (radius R = 0.15 m) Rim inner diameter <![CDATA[0.24 m (radius r1 = 0.12 m)]]> 403 inner diameter of central shaft hole <![CDATA[0.06 m (radius r2 = 0.03 m)]]> Flange thickness 0.075 m Disk thickness 0.015 m The calculation process of the moment of inertia of flywheel 4: Formula for calculating the moment of inertia of a hollow cylinder: ; Regarding the rim: ; ; For the spokes: ; ; Total moment of inertia: ; Back electromotive force constant of motor 3 torque constant armature resistance The total resistance of the power generation circuit is Main power voltage on board .

[0030] (2) Define the directions of the angular velocity and angular acceleration of the flywheel 4, motor 3, and hull, with clockwise as positive and counterclockwise as negative from the top viewpoint; Objective: To turn right to reach the target location. (3) Obtain the target heading angle θref and the ship's real-time speed to get the target angular velocity of the hull. Obtain target heading angle =150deg and the ship's real-time speed is 2.5m / s. The accelerometer, electronic compass, and gyroscope values ​​in the attitude sensing unit are read, and the current heading angle θ=100deg and real-time angular velocity are obtained through the data processing module. ; The real-time speed of motor 3 is obtained through feedback from motor 3. The direction is counterclockwise; The power management unit obtains the capacitor bank voltage in real time. .

[0031] Calculate the target angular velocity. The target angular velocity of the hull is obtained using the following formula. , ; ; in: Kp: Proportional gain, related to the ship's real-time speed; when the sailing speed is below 2 m / s, it is taken as... When the sailing speed is above 2m / s, take .

[0032] (4) Obtain the target angular acceleration of flywheel 4 based on the target angular velocity: The target angular acceleration of flywheel 4 is obtained using the following formula. , ; ; in: Angular velocity control gain, in s^-1, is the ratio of the moment of inertia of the hull to that of the flywheel. This ratio is the ratio of the magnitudes of their angular accelerations. Multiplying this ratio by 1 / 4 gives the result. The direction of the flywheel's angular acceleration is opposite to that of the ship's hull. ; (5) Calculate the target torque Td output by motor 3 based on the target angular acceleration of flywheel 4; The required output torque of motor 3 can be calculated using the following formula. , ; ; (6) Obtain the current direction and speed of motor 3: The real-time flywheel 4 rotates counterclockwise, matching the required output torque, and enters acceleration mode, calculating the duty cycle of the PWM signal controlling motor 3. .

[0033] Based on the relationship between voltage and rotational speed: Relationship between current and torque: The duty cycle can be derived. It can be calculated using the following formula: ; ; (7) Output signal to control motor 3: The main control unit output duty cycle is The PWM waveform controls the output torque of motor 3; Analysis of the ship's motion effect after outputting a specified torque: Flywheel 4 is of size Angular acceleration accelerates due to conservation of angular momentum ( ,in, Due to the effect of the ship's angular acceleration, the hull will move at an angle of -(0.31). ) / (1216 ()( ) 1.00 As the angular velocity increases, the yaw rate of the ship remains constant due to force balance under the influence of water resistance. As it approaches the target angle, ωd decreases, driving... As the output power decreases, the resistance is greater than the output power, causing the ship to decelerate and reach the target angle.

[0034] Objective: Turn right, then turn left back to center.

[0035] (3) Obtain the target heading angle θref and the ship's real-time speed to get the target angular velocity of the hull: Obtain the target heading angle θref=100deg and the ship's real-time speed V=2.2m / s; The accelerometer, electronic compass, and gyroscope values ​​in the attitude sensing unit are read, and the current heading angle θ=150deg and real-time angular velocity are obtained through the data processing module. ; The real-time speed of motor 3 is obtained through feedback from motor 3. The direction is counterclockwise; The power management unit obtains the capacitor bank voltage in real time. .

[0036] Calculate the target angular velocity: The target angular velocity of the hull is obtained using the following formula. , ; ; in: Kp: Proportional gain, related to the ship's real-time speed; when the sailing speed is below 2 m / s, it is taken as... When the sailing speed is above 2m / s, take .

[0037] (4) Obtain the target angular acceleration of flywheel 4 based on the target angular velocity: The target angular acceleration of flywheel 4 is obtained using the following formula. , ; ; in: Angular velocity control gain, in s^-1, the ratio of the moment of inertia of hull 1 to flywheel 4 is [value missing]. This ratio is the ratio of the magnitudes of their angular accelerations. Multiplying this ratio by 1 / 4 gives the result. The direction of the flywheel's angular acceleration is opposite to that of the ship's hull. .

[0038] (5) Based on the target angular acceleration of flywheel 4, the target torque Td output by motor 3 is calculated: The required output torque of motor 3 can be calculated using the following formula. , ; ; (6) Obtain the current direction and speed of motor 3: The real-time flywheel 4 rotates counterclockwise, while the required output torque is clockwise. Since the directions are different, it enters deceleration mode and calculates the duty cycle of the PWM signal that connects motor 3 to the capacitor bank for charging. .

[0039] Current generator voltage of motor 3 Maximum charging power when motor 3 is connected across energy storage capacitor bank 6 .

[0040] Current required deceleration power .

[0041] Based on maximum charging power Based on the reduction power P, the percentage of time that motor 3 is connected to the capacitor for charging can be calculated. ; (7) The final output signal controls motor 3: The main control unit outputs a command to instruct the power management unit to connect the positive and negative terminals of motor 3 to the capacitor bank for charging. The duty cycle of the connection time is... .

[0042] Analysis of the ship's motion effect after outputting a specified torque: Flywheel 4 is of size The angular acceleration decelerates, due to the conservation of angular momentum ( ,in, Due to the effect of the ship's angular acceleration, the hull will move at an angle of -(0.31). ) / (1216 (3922.58) ) -1.00 As the angular velocity increases, the yaw rate of the ship remains constant due to force balance under the influence of water resistance. As it approaches the target angle, ωd decreases, driving... As the output power decreases, the resistance is greater than the output power, causing the ship to decelerate and reach the target angle.

[0043] Objective: Turn left to reach the target location.

[0044] (3) Obtain the target heading angle θref and the ship's real-time speed to get the target angular velocity of the hull: Obtain target heading angle =80deg and the ship's real-time speed is 1.5m / s. The accelerometer, electronic compass, and gyroscope values ​​in the attitude sensing unit are read, and the current heading angle θ=100deg and real-time angular velocity are obtained through the data processing module. ; The real-time speed of motor 3 is obtained through feedback from motor 3. The direction is counterclockwise; The power management unit obtains the capacitor bank voltage in real time. .

[0045] (4) Obtain the target angular acceleration of flywheel 4 based on the target angular velocity: The target angular velocity of the hull is obtained using the following formula. , ; ; in: Kp: Proportional gain, related to the ship's real-time speed; when the sailing speed is below 2 m / s, it is taken as... When the sailing speed is above 2m / s, take .

[0046] Calculate the target angular acceleration of flywheel 4: The target angular acceleration of flywheel 4 is obtained using the following formula. , ; ; in: Angular velocity control gain, in s^-1, the ratio of the moment of inertia of hull 1 to flywheel 4 is [value missing]. This ratio is the ratio of the magnitudes of their angular accelerations. Multiplying this ratio by 1 / 4 gives the result. The direction of the flywheel's angular acceleration is opposite to that of the ship's hull. .

[0047] (5) Based on the target angular acceleration of flywheel 4, the target torque Td output by motor 3 is calculated: The required output torque of motor 3 can be calculated using the following formula. , ; ; (6) Obtain the current direction and speed of motor 3: The real-time flywheel 4 rotates counterclockwise, while the required output torque is clockwise. Since the directions are different, it enters deceleration mode and calculates the duty cycle of the PWM signal that connects motor 3 to the capacitor bank for charging. .

[0048] Current generator voltage of motor 3 Maximum charging power when motor 3 is connected across energy storage capacitor bank 6 .

[0049] Current required deceleration power , Based on maximum charging power Based on the reduction power P, the percentage of time that motor 3 is connected to the capacitor for charging can be calculated. ; (7) The final output signal controls motor 3: The main control unit outputs a command to instruct the power management unit to connect the positive and negative terminals of motor 3 to the capacitor bank for charging. The duty cycle of the connection time is... .

[0050] Analysis of the ship's motion effect after outputting a specified torque: Flywheel 4 has a size of 5883.9. The angular acceleration decelerates, due to the conservation of angular momentum ( ,in, Due to the effect of the ship's angular acceleration, the hull will move at an angle of -(0.31). ) / (1216 (5883.9) ) -1.50 As the angular velocity increases, the yaw rate of the ship remains constant due to force balance under the influence of water resistance. As it approaches the target angle, ωd decreases, driving... As the output power decreases, the resistance is greater than the output power, causing the ship to decelerate and reach the target angle.

[0051] Objective: Turn left, then turn right back to center.

[0052] (3) Obtain the target heading angle θref and the ship's real-time speed to get the target angular velocity of the hull: Obtain the target heading angle θref=100deg and the ship's real-time speed=1.6m / s; The accelerometer, electronic compass, and gyroscope values ​​in the attitude sensing unit are read, and the current heading angle θ=80deg and real-time angular velocity are obtained through the data processing module. ; The real-time speed of motor 3 is obtained through feedback from motor 3. The direction is clockwise; The power management unit obtains the capacitor bank voltage in real time. .

[0053] (4) Obtain the target angular acceleration of flywheel 4 based on the target angular velocity; The target angular velocity of the hull is obtained using the following formula. ; ; ; in: Kp: Proportional gain, related to the ship's real-time speed; when the sailing speed is below 2 m / s, it is taken as... When the sailing speed is above 2m / s, take .

[0054] Calculate the target angular acceleration of flywheel 4: The target angular acceleration of flywheel 4 is obtained using the following formula. , ; ; in: Angular velocity control gain, in s^-1, the ratio of the moment of inertia of hull 1 to flywheel 4 is [value missing]. This ratio is the ratio of the magnitudes of their angular accelerations. Multiplying this ratio by 1 / 4 gives... The direction of the flywheel's angular acceleration is opposite to that of the ship's hull. .

[0055] (5) Based on the target angular acceleration of flywheel 4, the target torque Td output by motor 3 is calculated: The required output torque of motor 3 can be calculated using the following formula. , ; ; (6) Obtain the current direction and speed of motor 3: The real-time flywheel 4 rotates counterclockwise, matching the required output torque, and enters acceleration mode, calculating the duty cycle of the PWM signal controlling motor 3. .

[0056] Based on the relationship between voltage and rotational speed: Relationship between current and torque: , derive the duty cycle It can be calculated using the following formula: ; ; (7) The final output signal controls motor 3: The main control unit output duty cycle is The PWM waveform controls the output torque of motor 3.

[0057] Analysis of the ship's motion effect after outputting a specified torque: Flywheel 4 is of size Angular acceleration accelerates due to conservation of angular momentum ( ,in, Due to the effect of the ship's angular acceleration, the hull will move at an angle of -(0.31). ) / (1216 (-4903.25) ) -1.25

[0058] As the angular velocity increases, the yaw rate of the ship remains constant due to force balance under the influence of water resistance. As it approaches the target angle, ωd decreases, driving... When the output power decreases (Td), the resistance becomes greater than the output power, causing the ship to decelerate and reach the target angle.

Claims

1. A steering method for a small unmanned surface vessel (USV) based on a momentum wheel steering structure, comprising a hull, characterized in that... The steering housing is fixedly connected to the middle of the hull. A steering structure is installed inside the steering housing, comprising a motor, flywheel, control system, and energy storage capacitor bank. The motor is fixed to the bottom of the steering housing, with its output shaft facing upwards and connected to the center of the flywheel. The control system includes a main control unit, an attitude sensing unit, a motor control unit, and a power management unit. The attitude sensing unit includes an accelerometer, an electronic compass, a gyroscope, and a data processing module. The accelerometer, electronic compass, and gyroscope are connected to the data processing module, which is connected to the main control unit. The main control unit is connected to the motor control unit and the power management unit. The power management unit is connected to the motor control unit, the motor control unit is connected to the motor, and the power storage capacitor bank is connected to the motor control unit, the motor, and the energy storage capacitor bank. The center of the flywheel is on the straight line where the center of mass of the hull is located. A propeller is installed at the bottom of the hull, and a drive motor is installed inside the hull. The output end of the drive motor is connected to the propeller. The flywheel includes a rim and a spoke portion. The rim is annular and its thickness is greater than that of the spoke portion. The rim fits over the outside of the spoke portion and is integrally connected to it. A central shaft hole is provided at the center of the spoke portion, and the central shaft hole is connected to the output shaft of the motor. The steps of the steering method for the small unmanned surface vessel with a steering structure are as follows: (1) Obtain parameters: ship length, width, weight, ship moment of inertia, flywheel diameter, weight, flywheel moment of inertia Jw, motor back electromotive force constant Ke, torque constant Kt, armature resistance Ra, total circuit resistance R of generator circuit, ship main power supply voltage. (2) Define the directions of the angular velocity and angular acceleration of the flywheel, motor, and hull, with clockwise as positive and counterclockwise as negative from the top viewpoint; (3) Obtain the target heading angle and the real-time speed of the ship to obtain the target angular velocity of the hull; (4) Obtain the target angular acceleration of the flywheel based on the target angular velocity; (5) Calculate the target torque output by the motor based on the target angular acceleration of the flywheel; (6) Obtain the current motor direction and speed: If the motor's rotation direction is the same as the flywheel's target angular acceleration direction, then the motor enters acceleration mode, controlling its acceleration. The duty cycle for controlling motor acceleration is then determined. , If the motor's rotation direction is opposite to the flywheel's target angular velocity direction, the motor enters deceleration mode. The deceleration power is calculated, and based on the maximum charging power and the deceleration power, the percentage of time the motor is connected to the capacitor for charging is calculated. ; (7) The final output signal controls the motor: In acceleration mode: the main control unit output duty cycle is The PWM waveform controls the motor's output torque, and the motor can automatically output the specified power according to the PWM waveform requirements. In deceleration mode: The main control unit outputs a command to instruct the power management unit to connect the positive and negative terminals of the motor to the capacitor bank, with a duty cycle of [duty cycle missing]. , (8) Loop calculation: After outputting the control signal, loop to step (3) - step (7) to repeat the whole process; each loop changes various data dynamically, and the algorithm also dynamically adjusts the output torque and motor output power accordingly.

2. The steering method for a small unmanned surface vessel based on a momentum wheel steering structure according to claim 1, characterized in that... In step (3), the specific steps are: reading the values ​​of the accelerometer, electronic compass, and gyroscope in the attitude sensing unit and obtaining the current heading angle and real-time speed through the data calculation module; According to the formula Obtain the target angular velocity of the ship; Kp: Proportional gain, related to the ship's real-time speed; taken as 0.3s^ when the sailing speed is below 2m / s. -1 For speeds above 2 m / s, take 0.1 s^2. -1 Target heading angle Unit: deg; Current heading angle θ; Unit: deg; Target angular velocity of the ship. ,unit .

3. The steering method for a small unmanned surface vessel based on a momentum wheel steering structure according to claim 1, characterized in that... In step (4), the specific steps are as follows: according to the following formula; ； in: Angular velocity control gain, in seconds (s^-1), is the ratio of the moment of inertia of the hull to that of the flywheel. This ratio is the ratio of their angular accelerations. Multiplying this ratio by 1 / 4 yields the result. The direction of the wheel's angular acceleration is opposite to that of the hull. Take a negative number; the direction of the wheel angular acceleration is the same as that of the hull. Take positive numbers. For target angular acceleration, in units Real-time angular velocity The unit is .

4. The steering method for a small unmanned surface vessel based on a momentum wheel steering structure according to claim 1, characterized in that... In step (5), the specific steps are as follows: according to the following formula; ; in: Target angular acceleration of the flywheel, in units , The moment of inertia of the flywheel, in units of , This represents the torque that the motor needs to output, in units of... .

5. The steering method for a small unmanned surface vessel based on a momentum wheel steering structure according to claim 1, characterized in that... In step (6), the duty cycle for controlling the motor acceleration is... The specific calculation steps are as follows: Based on the relationship between voltage and rotational speed: Relationship between torque and current: It can be deduced that the duty cycle for controlling the acceleration of the motor is... ， Where V is the armature voltage, measured in volts (V), which is the supply voltage multiplied by the duty cycle. ; η is the power supply voltage, in volts (V); n is the angular velocity of the motor, in cubic meters (Ω). I represents the motor current, in units of... , Armature resistance, unit: , Motor torque, unit: , The value is , The torque constant is expressed in units of 1000 ppm. , The back electromotive force constant of the motor is given by . .

6. The steering method for a small unmanned surface vessel based on a momentum wheel steering structure according to claim 1, characterized in that... In step (6), the method for calculating the deceleration power P is as follows: The calculation method for the maximum charging power Pm is as follows: Based on the current speed and capacitor voltage, the maximum charging power when the motor is connected across the energy storage capacitor bank is obtained. Where Vcap is the voltage across the capacitor, in volts (V), obtained from the power management module; the motor generator voltage is... n is the angular velocity of the motor, and the unit is angular velocity. , The back electromotive force constant of the motor is given by . The total resistance R of the power generation circuit is measured in units of... The calculation method for the percentage of time N2 that the motor spends charging the capacitor is as follows: P represents the reduction power, measured in watts (W). This represents the maximum charging power, measured in watts (W).

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