Rotation speed control method and device of underwater propeller, storage medium and electronic equipment

Abstract

The invention provides a rotating speed control method and device of an underwater propeller, a storage medium and electronic equipment, and belongs to the technical field of control, and the method comprises the steps: obtaining a voltage signal and a current signal corresponding to the underwater propeller; determining an actual rotating speed corresponding to the underwater propeller according to the voltage signal and the current signal; performing load torque estimation on the underwater propeller based on the actual rotating speed to obtain an actual load torque corresponding to the underwater propeller; determining a current target thrust value, and determining a target load torque corresponding to the target thrust value; determining a target rotating speed according to the target load torque and the actual load torque; determining target current according to the actual rotating speed and the target rotating speed; determining a voltage driving signal according to the target current and the current signal; and controlling the rotating speed of the underwater propeller based on the voltage driving signal. By applying the method, feedback control can be performed on the rotating speed of the propeller in combination with the actual load state of the propeller, and the stability and accuracy of motion control can be improved.

Description

Technical Field

[0001] The present invention relates to the field of control technology, and in particular to a rotation speed control method and device for an underwater thruster, a storage medium and an electronic device. Background Art

[0002] Underwater robots (Remote Operated Vehicle, ROV) are one of the common equipment in the field of marine research. Underwater robots are usually equipped with underwater thrusters as power modules. The thrust generated by the operation of the underwater thrusters is used to achieve motion control of the underwater robot.

[0003] At present, underwater thrusters configured in underwater robots usually use electronic speed controllers (ESC) for speed control. ESC mainly uses pulse width modulation (PWM) signals for drive control, that is, it uses square wave signals to drive and control according to the preset corresponding speed under different thrust requirements.

[0004] During the actual operation of the underwater robot, the underwater thruster may need to work near the water surface. At this time, the underwater thruster will inhale the air-water mixture, resulting in the thrust generated at the same speed being much smaller than the underwater thrust. This phenomenon is called the quasi-cavitation effect. Based on the existing speed control method, when the underwater thruster produces the quasi-cavitation effect, it is impossible to identify that the underwater thruster is not actually in a normal operating state. The underwater thruster can only be controlled according to the preset normal speed. The actual thrust generated is usually inconsistent with the actual demand, which can easily cause the posture and position of the underwater robot to fluctuate, resulting in poor accuracy and stability of motion control. Summary of the invention

[0005] In view of this, an embodiment of the present invention provides a speed control method for an underwater thruster to solve the problem that the existing speed control method for an underwater thruster can only be controlled according to a preset speed. When the underwater thruster produces a cavitation-like effect, it cannot stably generate the required thrust, resulting in poor stability and accuracy of motion control.

[0006] The embodiment of the present invention also provides a speed control device for an underwater thruster to ensure the practical implementation and application of the above method.

[0007] To achieve the above objectives, the embodiments of the present invention provide the following technical solutions:

[0008] A method for controlling the rotation speed of an underwater propeller, comprising:

[0009] Obtaining voltage signals and current signals corresponding to the underwater thruster;

[0010] Determining an actual rotation speed corresponding to the underwater propeller according to the voltage signal and the current signal;

[0011] Based on the actual rotation speed, estimating the load torque of the underwater propeller to obtain the actual load torque corresponding to the underwater propeller;

[0012] Determining a current target thrust value, and determining a target load torque corresponding to the target thrust value;

[0013] Determining a target speed according to the target load torque and the actual load torque;

[0014] Determining a target current according to the actual speed and the target speed;

[0015] Determining a voltage driving signal according to the target current and the current signal;

[0016] The rotation speed of the underwater thruster is controlled based on the voltage driving signal.

[0017] In the above method, optionally, determining the actual rotation speed corresponding to the underwater propeller according to the voltage signal and the current signal includes:

[0018] Based on the voltage signal, the current signal and a pre-constructed nonlinear flux observer, a motor rotor angle signal is determined; the non-linear flux observer is an observer constructed based on the electrical parameters of the motor of the underwater thruster;

[0019] Determine a rotor speed signal corresponding to the motor rotor angle signal;

[0020] The rotor speed signal is speed-converted to obtain a propeller speed corresponding to the underwater propeller, and the propeller speed is used as an actual speed corresponding to the underwater propeller.

[0021] In the above method, optionally, estimating the load torque of the underwater propeller based on the actual rotation speed to obtain the actual load torque corresponding to the underwater propeller includes:

[0022] Based on the actual rotation speed and a pre-constructed extended state observer, a real-time observation value of the load torque expansion state variable is determined; the extended state observer is an observer constructed based on the motor mechanical constant and the motor differential equation of the underwater propeller;

[0023] Determining a load torque observation value based on the real-time observation value of the load torque expansion state variable;

[0024] The load torque observation value is used as the actual load torque corresponding to the underwater thruster.

[0025] In the above method, optionally, determining the target current according to the actual speed and the target speed includes:

[0026] Performing a difference operation on the target speed and the actual speed to obtain a first operation result;

[0027] Performing a product operation on a preset proportional factor and the first operation result to obtain a second operation result;

[0028] Obtaining magnetic flux parameters, magnetic pole pairs and moment of inertia corresponding to the underwater thruster;

[0029] Performing a product operation on the moment of inertia and the real-time observed value of the load torque expansion state variable to obtain a third operation result;

[0030] Performing a product operation on a preset constant, the flux linkage parameter and the number of magnetic pole pairs to obtain a fourth operation result;

[0031] Dividing the third operation result by the fourth operation result to obtain a fifth operation result;

[0032] The second operation result and the fifth operation result are summed, and the operation result is used as the target current.

[0033] In the above method, optionally, the determining the target load torque corresponding to the target thrust value comprises:

[0034] Determine a propeller parameter set corresponding to the underwater propeller; the propeller parameter set includes a propeller torque coefficient, a propeller thrust coefficient and a propeller blade diameter;

[0035] Based on the propeller parameter set, the target thrust value and a preset thrust-load torque function relationship, a load torque value corresponding to the target thrust value is calculated, and the load torque value corresponding to the target thrust value is used as the target load torque.

[0036] In the above method, optionally, determining the target speed according to the target load torque and the actual load torque includes:

[0037] Performing a difference operation on the target load torque and the actual load torque, and taking the operation result as the load torque difference;

[0038] Performing an integration operation on the load torque difference to obtain a first integration result;

[0039] Performing a product operation on a preset load loop integral term and the first integral result to obtain a sixth operation result;

[0040] Performing a product operation on a preset load loop proportional term and the load torque difference to obtain a seventh operation result;

[0041] A sum operation is performed on the sixth operation result and the seventh operation result, and the operation result is used as the target rotation speed.

[0042] In the above method, optionally, determining the voltage driving signal according to the target current and the current signal includes:

[0043] Determine the actual q-axis current corresponding to the current signal;

[0044] Performing a difference operation on the target current and the actual current of the q-axis, and taking the operation result as the current difference value;

[0045] Performing an integration operation on the current difference to obtain a second integration result;

[0046] Performing a product operation on a preset current loop proportional term and the current difference to obtain an eighth operation result;

[0047] Performing a product operation on a preset current loop integral term and the second integral result to obtain a ninth operation result;

[0048] performing a sum operation on the eighth operation result and the ninth operation result, and taking the operation result as the q-axis target voltage;

[0049] The voltage drive signal is determined based on the q-axis target voltage.

[0050] A speed control device for an underwater propeller, comprising:

[0051] A signal acquisition unit, used to acquire a voltage signal and a current signal corresponding to the underwater thruster;

[0052] A first determining unit, configured to determine an actual rotation speed corresponding to the underwater propeller according to the voltage signal and the current signal;

[0053] a torque estimation unit, configured to estimate the load torque of the underwater propeller based on the actual rotation speed, and obtain an actual load torque corresponding to the underwater propeller;

[0054] A second determining unit, configured to determine a current target thrust value and a target load torque corresponding to the target thrust value;

[0055] A third determining unit, configured to determine a target speed according to the target load torque and the actual load torque;

[0056] a fourth determining unit, configured to determine a target current according to the actual speed and the target speed;

[0057] a fifth determining unit, configured to determine a voltage driving signal according to the target current and the current signal;

[0058] A rotation speed control unit is used to control the rotation speed of the underwater thruster based on the voltage drive signal.

[0059] A storage medium includes stored instructions, wherein when the instructions are executed, the device where the storage medium is located is controlled to execute the above-mentioned method for controlling the rotation speed of an underwater propeller.

[0060] An electronic device comprises a memory and one or more instructions, wherein the one or more instructions are stored in the memory and are configured to be executed by one or more processors to implement the rotation speed control method of an underwater thruster as described above.

[0061] A speed control method for an underwater propeller provided based on the above-mentioned embodiment of the present invention includes: obtaining a voltage signal and a current signal corresponding to the underwater propeller; determining the actual speed corresponding to the underwater propeller according to the voltage signal and the current signal; estimating the load torque of the underwater propeller based on the actual speed, and obtaining the actual load torque corresponding to the underwater propeller; determining the current target thrust value, and determining the target load torque corresponding to the target thrust value; determining the target speed according to the target load torque and the actual load torque; determining the target current according to the actual speed and the target speed; determining the voltage drive signal according to the target current and the current current signal; and controlling the speed of the underwater propeller based on the voltage drive signal. By applying the method provided by the embodiment of the present invention, the actual speed and actual load torque of the propeller can be observed based on the real-time voltage signal and real-time current signal of the underwater propeller motor. Combined with the feedback of the actual speed and the actual load torque of the propeller, the corresponding target current is determined, and then the voltage drive signal is determined, thereby controlling the speed of the propeller. During the speed control process, the speed can be feedback controlled in combination with the actual load state of the thruster. When abnormal phenomena such as cavitation effect occur in the thruster, it can stably generate thrust that matches the required thrust, so that the underwater robot can maintain the required posture and position, which is conducive to improving the accuracy and stability of motion control. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0063] Figure 1A method flow chart of a method for controlling the rotation speed of an underwater propeller provided by an embodiment of the present invention;

[0064] Figure 2 A schematic diagram of the hardware architecture of an underwater thruster control platform provided in an embodiment of the present invention;

[0065] Figure 3 A schematic diagram of a speed control process of an underwater propeller provided by an embodiment of the present invention;

[0066] Figure 4 An exemplary diagram of a current control effect provided by an embodiment of the present invention;

[0067] Figure 5 An example diagram of a speed control effect provided by an embodiment of the present invention;

[0068] Figure 6 An exemplary diagram of a load control effect provided by an embodiment of the present invention;

[0069] Figure 7 A schematic structural diagram of a speed control device for an underwater thruster provided in an embodiment of the present invention;

[0070] Figure 8 A schematic diagram of the structure of an electronic device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0071] 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.

[0072] In this application, the terms "comprises", "comprising" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising 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. In the absence of further restrictions, an element defined by the sentence "comprising a ..." does not exclude the presence of other identical elements in the process, method, article or device comprising the element.

[0073] The embodiment of the present invention provides a method for controlling the speed of an underwater propeller. The method can be applied to a speed control module of the underwater propeller. The execution subject can be a processor of the speed control module. The method flow chart of the method is as follows: Figure 1 As shown, including:

[0074] S101: Acquire a voltage signal and a current signal corresponding to an underwater thruster;

[0075] The method provided in the embodiment of the present invention can be used to control the speed of an underwater propeller configured in an underwater robot. The underwater propeller in this article is referred to as a propeller. The speed control module of the propeller can collect the voltage signal and current signal of the propeller motor in real time, and control the speed of the propeller based on the voltage signal and the current signal.

[0076] S102: determining an actual rotation speed corresponding to the underwater propeller according to the voltage signal and the current signal;

[0077] The method provided by the embodiment of the present invention is based on the principle of Field Oriented Control (FOC) technology for speed control. The idea of ​​FOC technology is to decompose the stator current of the motor into two mutually perpendicular components, one component is responsible for generating magnetic flux, which is called excitation current or d-axis current, and the other component is responsible for generating torque, which is called torque current or q-axis current. The d-axis current controls the magnetic flux of the motor. The q-axis current controls the torque of the motor, which is related to the speed and load of the motor. Correspondingly, the voltage can also be decomposed into corresponding components. In the component conversion of current or voltage, the three-phase stationary coordinate system (a, b, c) can be converted into a two-phase stationary coordinate system (α, β) by Clarke transformation, that is, the current is decomposed into α-phase current and β-phase current, or the voltage is decomposed into α-phase voltage and β-phase voltage. The two-phase stationary coordinate system can be converted into a rotating coordinate system (d, q) by Park transformation, that is, the α-phase current and the β-phase current are converted into the d-axis current and the q-axis current, or the α-phase voltage and the β-phase voltage are converted into the d-axis voltage and the q-axis voltage.

[0078] In the method provided in the embodiment of the present invention, the current actual speed of the motor can be determined based on the voltage signal and current signal of the propeller motor through FOC technology. Specifically, a nonlinear flux observer can be used to observe the electronic rotor position to calculate the actual speed of the motor, that is, the propeller speed of the propeller.

[0079] S103: estimating the load torque of the underwater propeller based on the actual rotation speed to obtain the actual load torque corresponding to the underwater propeller;

[0080] In the method provided in the embodiment of the present invention, the load torque of the propeller can be estimated based on the mathematical model of the propeller and the actual speed of the propeller, and the estimated load torque can be used as the actual load torque of the propeller. Specifically, the load torque can be used as an extended amount and extracted based on an extended state observer (ESO).

[0081] S104: determining a current target thrust value, and determining a target load torque corresponding to the target thrust value;

[0082] In the method provided by the embodiment of the present invention, the speed control module can determine the current target thrust value, that is, the magnitude of the thrust that the current thruster needs to generate, according to the current thrust setting instruction. And according to the current target thrust value, the load torque of the thruster under the thrust state corresponding to the target thrust value is calculated, and the calculated load torque is used as the target load torque.

[0083] S105: determining a target speed according to the target load torque and the actual load torque;

[0084] In the method provided in the embodiment of the present invention, a load feedback loop can be constructed in advance according to actual needs, the actual load torque of the propeller is used as feedback information, the target load torque is used as the expected target, and the speed is used as the output of feedback control. The current target load torque and the actual load torque are used as input information of the load feedback loop, and the load feedback loop is used to calculate the output speed, and the speed is used as the target speed.

[0085] S106: determining a target current according to the actual speed and the target speed;

[0086] In the method provided in the embodiment of the present invention, a speed loop can be constructed in advance according to actual needs, the actual speed of the propeller is used as feedback information, the speed expected to be achieved by the propeller is used as the expected target, and the current of the motor is used as the output of the feedback control. In the speed control process, the actual speed and target speed corresponding to the current propeller are used as input information, the speed loop is used to calculate the current adaptation value, and the calculated current value is used as the target current.

[0087] S107: determining a voltage driving signal according to the target current and the current signal;

[0088] In the method provided by the embodiment of the present invention, a current loop can be constructed in advance according to actual needs, the actual current of the propeller is used as feedback information, the current current to be set is used as the expected target, and the voltage of the motor is used as the output of the feedback control. In the speed control process, the target current and current signal corresponding to the current propeller are used as input information, the current loop is used to calculate the current adapted voltage value, and the corresponding voltage drive signal is generated based on the voltage value.

[0089] S108: Based on the voltage drive signal, the rotation speed of the underwater thruster is controlled.

[0090] In the method provided by the embodiment of the present invention, the motor of the underwater thruster is driven by the currently generated voltage driving signal, so that the motor runs at a rotation speed corresponding to the corresponding voltage.

[0091] Based on the method provided by the embodiment of the present invention, in the process of speed control of the underwater propeller, the voltage signal and current signal corresponding to the underwater propeller can be obtained; based on the voltage signal and the current signal, the actual speed corresponding to the underwater propeller is determined; based on the actual speed, the load torque of the underwater propeller is estimated to obtain the actual load torque corresponding to the underwater propeller; the current target thrust value is determined, and the target load torque corresponding to the target thrust value is determined; based on the target load torque and the actual load torque, the target speed is determined; based on the actual speed and the target speed, the target current is determined; based on the target current and the current current signal, the voltage drive signal is determined; based on the voltage drive signal, the speed of the underwater propeller is controlled. By applying the method provided by the embodiment of the present invention, the actual speed and actual load torque of the propeller can be observed based on the real-time voltage signal and real-time current signal of the underwater propeller motor. Combined with the feedback of the actual speed and the actual load torque of the propeller, the corresponding target current is determined, and then the voltage drive signal is determined, thereby controlling the speed of the propeller. During the speed control process, the speed can be feedback controlled in combination with the actual load state of the thruster. When abnormal phenomena such as cavitation effect occur in the thruster, it can stably generate thrust that matches the required thrust, so that the underwater robot can maintain the required posture and position, which is conducive to improving the accuracy and stability of motion control.

[0092] exist Figure 1 On the basis of the method shown, in the method provided by the embodiment of the present invention, the process of determining the actual rotation speed corresponding to the underwater propeller according to the voltage signal and the current signal mentioned in step S102 includes:

[0093] Based on the voltage signal, the current signal and a pre-constructed nonlinear flux observer, a motor rotor angle signal is determined; the non-linear flux observer is an observer constructed based on the electrical parameters of the motor of the underwater thruster;

[0094] In the method provided in the embodiment of the present invention, a nonlinear flux observer can be constructed in advance based on electrical parameters such as resistance, inductance and flux parameters of the thruster motor to observe the motor rotor position that cannot be directly measured. The mathematical model of the specifically constructed nonlinear flux observer can be as follows:

[0095] (Formula 1)

[0096] (Formula 2)

[0097] Where R is the resistance parameter of the thruster motor, L is the inductance parameter of the thruster motor, φ represents the flux parameter of the thruster motor, λ represents the gain factor to be adjusted, [u α u β ] T Indicates the voltage signal decoupled into phase α and phase β, u α is the voltage component of phase α, u β is the voltage component of the β phase, [i α i β ] T represents the current signal decoupled into phase α and phase β, i α is the current component of phase α, i β is the current component of the β phase. [x 1 x 2 ] T Represents a composite signal that cannot be directly measured. The signal contains the angle information of the motor rotor. represents the observed signal of the composite signal, represents the differential signal of the observed signal, and θ represents the angle signal of the motor rotor. The nonlinear flux model only needs to adjust the gain factor λ to make the observer converge, obtain the rotor angle, and then obtain the rotor speed.

[0098] In the process of speed control, the voltage signal and current signal of the current thruster can be decoupled by FOC technology to obtain the voltage signal decoupled into α phase and β phase and the current signal decoupled into α phase and β phase. Based on the decoupled voltage signal and current signal, the pre-built nonlinear flux observer is used to observe the angle information of the motor rotor to obtain the observation signal , the observed signal is compared with the actual measured signal By subtracting, the motor rotor angle signal θ can be obtained.

[0099] Determine a rotor speed signal corresponding to the motor rotor angle signal;

[0100] In the method provided in the embodiment of the present invention, a differential operation can be performed on the motor rotor angle signal, and the operation result is the corresponding rotor speed signal. m The operation method of can be shown as follows:

[0101] (Formula 3)

[0102] The rotor speed signal is speed-converted to obtain a propeller speed corresponding to the underwater propeller, and the propeller speed is used as an actual speed corresponding to the underwater propeller.

[0103] In the method provided in an embodiment of the present invention, the conversion relationship between the motor rotor speed and the rotational speed of the propeller driven by the motor can be pre-set based on the conversion relationship between the motor mechanical speed and the electrical speed. According to the preset conversion relationship, the current rotor speed signal is converted and calculated to obtain the corresponding propeller rotational speed, and the calculated propeller rotational speed is used as the actual rotational speed corresponding to the propeller.

[0104] The calculation principle of propeller speed w can be shown as follows:

[0105] (Formula 4)

[0106] Among them, p n Indicates the number of pole pairs of the motor.

[0107] exist Figure 1 On the basis of the method shown, in the method provided by the embodiment of the present invention, the process of estimating the load torque of the underwater propeller based on the actual rotation speed mentioned in step S103 to obtain the actual load torque corresponding to the underwater propeller includes:

[0108] Based on the actual rotation speed and a pre-constructed extended state observer, a real-time observation value of the load torque expansion state variable is determined; the extended state observer is an observer constructed based on the motor mechanical constant and the motor differential equation of the underwater propeller;

[0109] In the method provided in the embodiment of the present invention, a corresponding extended state observer ESO can be constructed in advance based on the mechanical constants such as the motor moment of inertia, electromagnetic torque, and the motor differential equation describing the motor motion state. Specifically, a second-order state observer needs to be designed according to the differential equation model of the motor. The first-order signal is the speed observation signal, and the second-order signal is the load torque observation signal. The mathematical model of the second-order observer constructed in the embodiment of the present invention (i.e., the constructed extended state observer) can be shown as follows:

[0110] (Formula 5)

[0111] Among them, e w is the speed observation error, J is the motor’s moment of inertia, T e is the electromagnetic torque of the motor, z 1 is the expanded state variable related to the velocity observation signal, z 2 is the expanded state variable related to the load torque observation signal (i.e., the load torque expanded state variable), and Respectively represent the derivative signals of the corresponding expanded state variables. 1 and β 2 is the parameter to be adjusted, by adjusting β 1 and β 2The bandwidth of the state observer can be adjusted, and the relationship between the bandwidth and these two parameters can be shown as follows:

[0112] (Formula 6)

[0113] (Formula 7)

[0114] Among them, w o is the bandwidth of the state observer.

[0115] During the speed control process, the actual speed w is used as the input information of the extended state observer, and the extended state observer is used to observe the load torque signal of the motor to obtain the extended state variable related to the load torque observation signal, that is, the real-time observation value of the load torque extended state variable.

[0116] Determining a load torque observation value based on the real-time observation value of the load torque expansion state variable;

[0117] In the method provided in the embodiment of the present invention, the correlation between the load torque expansion state variable and the load torque signal can be preset according to the differential equation of the motor. In the speed control process, the corresponding load torque observation value can be calculated based on the real-time observation value of the current load torque expansion state variable and the correlation between the load torque expansion state variable and the load torque signal. Based on the extended state observer model shown in Formula 5, in the embodiment of the present invention, the load torque observation value T L_back The calculation method of can be shown as follows:

[0118] (Formula 8)

[0119] The load torque observation value is used as the actual load torque corresponding to the underwater thruster.

[0120] In the method provided by the embodiment of the present invention, the load torque observation value calculated based on the real-time observation value of the load torque expansion state variable is used as the actual load torque of the thruster.

[0121] On the basis of the method provided in the above embodiment, in the method provided in the embodiment of the present invention, the process of determining the target current according to the actual speed and the target speed mentioned in step S106 includes:

[0122] Performing a difference operation on the target speed and the actual speed to obtain a first operation result;

[0123] Performing a product operation on a preset proportional factor and the first operation result to obtain a second operation result;

[0124] Obtaining magnetic flux parameters, magnetic pole pairs and moment of inertia corresponding to the underwater thruster;

[0125] Performing a product operation on the moment of inertia and the real-time observed value of the load torque expansion state variable to obtain a third operation result;

[0126] Performing a product operation on a preset constant, the flux linkage parameter and the number of magnetic pole pairs to obtain a fourth operation result;

[0127] Dividing the third operation result by the fourth operation result to obtain a fifth operation result;

[0128] The second operation result and the fifth operation result are summed, and the operation result is used as the target current.

[0129] In the method provided in the embodiment of the present invention, an extended state observer ESO is used to construct a speed loop of a linear active disturbance rejection control (LADRC) to control the motor q-axis current, that is, the current component related to the speed. Based on the extended state observer shown in equation 5, the mathematical model of the speed loop involved in the embodiment of the present invention can be shown as follows:

[0130] (Formula 9)

[0131] Among them, i q_ref Indicates the current output by the speed loop, that is, the target current, w ref represents the target speed, w represents the actual speed, K pw is the proportional factor, φ represents the flux parameter of the motor, and p n Indicates the number of magnetic pole pairs of the motor, z 2 represents the real-time observation value of the load torque expansion state variable, and the preset constant in the embodiment of the present invention is 1.5. Under this design, the speed link is simplified to the first-order inertia link as shown in the following formula:

[0132] (Formula 10)

[0133] Where T represents the system time constant and s represents the complex frequency domain variable.

[0134] During the speed control process, the target current of the motor q-axis can be calculated based on the current actual speed and the target speed by applying the calculation method shown in Formula 9. Specifically, the difference between the target speed and the actual speed is calculated, and the product of the difference and the preset proportional factor is used as the first product. The product of the real-time observation value of the motor moment of inertia and the load torque expansion state variable is used as the second product, and the product of the preset constant (1.5), the number of motor poles and the flux linkage parameter is used as the third product. The quotient of the second product and the third product is calculated, and the sum of the calculated quotient and the first product is used as the q-axis current of the current feedback control output, that is, the target current.

[0135] exist Figure 1 On the basis of the method shown, in the method provided by the embodiment of the present invention, the step S104 of determining the target load torque corresponding to the target thrust value includes:

[0136] Determine a propeller parameter set corresponding to the underwater propeller; the propeller parameter set includes a propeller torque coefficient, a propeller thrust coefficient and a propeller blade diameter;

[0137] In the method provided in the embodiment of the present invention, propeller parameters such as propeller torque coefficient, propeller thrust coefficient and propeller blade diameter of the propeller can be obtained from pre-stored propeller attribute data.

[0138] Based on the propeller parameter set, the target thrust value and a preset thrust-load torque function relationship, a load torque value corresponding to the target thrust value is calculated, and the load torque value corresponding to the target thrust value is used as the target load torque.

[0139] In the method provided in the embodiment of the present invention, the functional relationship between thrust and load torque can be set in advance according to the empirical formula of thrust and torque of the propeller. Specifically, the load torque T L The empirical formula for the thrust F can be shown as follows:

[0140] (Formula 11)

[0141] (Formula 12)

[0142] Among them, K Q is the propeller torque coefficient, K F represents the propeller thrust coefficient, ρ represents the density of the medium involved in the blade, w represents the motor speed, and D represents the propeller blade diameter of the propeller.

[0143] According to equations 11 and 12, the functional relationship between thrust and load torque can be obtained:

[0144] (Formula 13)

[0145] When the target thrust value, that is, the thrust is known, the load torque value corresponding to the target thrust value can be calculated according to the relationship shown in Formula 13, and the calculated load torque value is used as the current target load torque. Specifically, the product of the target thrust value, the propeller torque coefficient and the propeller blade diameter can be calculated, and the quotient of the product and the propeller thrust coefficient is the load torque value.

[0146] exist Figure 1On the basis of the method shown in the figure, in the method provided by the embodiment of the present invention, the process of determining the target speed according to the target load torque and the actual load torque mentioned in step S105 includes:

[0147] Performing a difference operation on the target load torque and the actual load torque, and taking the operation result as the load torque difference;

[0148] Performing an integration operation on the load torque difference to obtain a first integration result;

[0149] Performing a product operation on a preset load loop integral term and the first integral result to obtain a sixth operation result;

[0150] Performing a product operation on a preset load loop proportional term and the load torque difference to obtain a seventh operation result;

[0151] A sum operation is performed on the sixth operation result and the seventh operation result, and the operation result is used as the target rotation speed.

[0152] In the method provided in the embodiment of the present invention, the actual load is used as a feedback signal to construct a load feedback loop, and the load feedback loop is specifically constructed using the mechanism of a PI (proportional integral) controller, that is, the load feedback loop can be regarded as a PI controller of a load torque. The input of the load feedback loop is the target load torque and the actual load torque, and the output is the target speed of the motor. The model of the load feedback loop in the embodiment of the present invention can be shown as follows:

[0153] (Formula 14)

[0154] Among them, T L_ref is the target load torque, T L_back is the actual load torque (i.e. the observed signal of the load), K pt K is the load loop proportional item set according to actual needs. it It is the load loop integral item set according to actual needs.

[0155] In the speed control process, the target speed can be calculated based on the current target load torque and the actual load torque by applying the load feedback loop shown in Formula 4 through load feedback control. Specifically, the difference between the target load torque and the actual load torque is calculated to obtain the load torque difference. The product of the load torque difference and the load loop proportional term is calculated, and the load torque difference is integrated, and the product of the load loop integral term and the integral result of the load torque difference is calculated. The product of the load torque difference and the load loop proportional term and the product of the load loop integral term and the integral result of the load torque difference are summed, and the sum of the two products is used as the current target speed.

[0156] exist Figure 1On the basis of the method shown, in the method provided by the embodiment of the present invention, the process of determining the voltage driving signal according to the target current and the current signal mentioned in step S107 includes:

[0157] Determine the actual q-axis current corresponding to the current signal;

[0158] Performing a difference operation on the target current and the actual current of the q-axis, and taking the operation result as the current difference value;

[0159] Performing an integration operation on the current difference to obtain a second integration result;

[0160] Performing a product operation on a preset current loop proportional term and the current difference to obtain an eighth operation result;

[0161] Performing a product operation on a preset current loop integral term and the second integral result to obtain a ninth operation result;

[0162] performing a sum operation on the eighth operation result and the ninth operation result, and taking the operation result as the q-axis target voltage;

[0163] The voltage drive signal is determined based on the q-axis target voltage.

[0164] In the method provided in the embodiment of the present invention, the motor speed is controlled based on the control principle of FOC, so the motor state variables need to be decoupled, and the electromagnetic torque of the motor is controlled by controlling the q-axis current, thereby controlling the speed. In the embodiment of the present invention, the actual q-axis current is used as a feedback signal to construct a current loop, and a PI controller is specifically used to construct the current loop, that is, the current loop can be regarded as a current PI controller. The input of the current loop is the currently set target current (which is the q-axis current) and the q-axis current component in the actual current signal, and the output is the q-axis voltage component used to control the motor, that is, the q-axis target voltage. In the embodiment of the present invention, the motor is regarded as a first-order equivalent circuit, and the PI parameters of the current loop are designed according to parameters such as the motor inductance and resistance. In the embodiment of the present invention, the current loop PI parameters, the current loop proportional term K pq and the current loop integral term K iq The design can be shown as follows:

[0165] (Formula 15)

[0166] (Formula 16)

[0167] Among them, w i is the bandwidth of the current loop, which can be set according to the actual sampling period and hardware performance. L represents the motor inductance parameter, and R represents the motor resistance parameter.

[0168] The design method of the current loop in the embodiment of the present invention can be as follows:

[0169] (Formula 17)

[0170] Among them, i q_ref represents the target current, i q Indicates the q-axis current in the actual current signal, u q It is the q-axis target voltage of the current loop output.

[0171] In the process of speed control, the q-axis current component can be obtained from the current actual current signal by decoupling through FOC technology, and the q-axis current component is used as the q-axis actual current corresponding to the current signal. It can be understood that the target current in the embodiment of the present invention is also a current component on the q-axis. The target current and the q-axis actual current are used as the input of the current loop, and the current feedback control method is applied to calculate the current desired q-axis target voltage. Specifically, the difference between the target current and the q-axis actual current is calculated to obtain the current difference. The product of the current difference and the current loop proportional term is calculated, and the current difference is integrated, and the product of the current loop integral term and the integral result of the current difference is calculated. The product of the current difference and the current loop proportional term and the product of the current loop integral term and the integral result of the current difference are summed, and the sum of the two products is used as the current q-axis target voltage. The q-axis target voltage is used as the q-axis voltage, and the space vector pulse width modulation (SVPWM) technology is applied to construct the voltage drive signal of the three-phase voltage.

[0172] In order to better illustrate the method provided by the embodiment of the present invention, based on the methods provided by the previous embodiments and in combination with actual application scenarios, the embodiment of the present invention provides another method for controlling the speed of an underwater propeller. The method provided by the embodiment of the present invention can be applied to the control scenario of an underwater robot, and the underwater robot can be equipped with multiple underwater propellers, for example, 8 propellers. The hardware architecture diagram of the propeller control platform in the embodiment of the present invention can be shown as follows: Figure 2 As shown, it specifically includes: a host computer 201, a main control board 202, a motor drive board 203 and a thruster 204. The host computer is responsible for communicating with the shore-based computer, the main control board is responsible for settling control information, that is, for executing operations related to speed control, and the motor drive board is used to drive the thruster motor.

[0173] The design idea of ​​the method provided in the embodiment of the present invention is to use FOC technology to realize the decoupling of motor state variables. On the basis of FOC, the state observer is designed using the state equation of the motor and the decoupling signal to detect the thruster state variables that are difficult to measure directly, such as underwater speed and underwater load. The load torque information is further used to design a load torque controller to realize the load torque-speed-current three-loop control. By controlling the torque balance, the thrust output of the thruster is guaranteed to be stable in various working environments such as near the water surface.

[0174] The specific design process of the method provided in the embodiment of the present invention mainly includes:

[0175] Motor equation modeling;

[0176] A motor differential equation model is established and a nonlinear flux observer is constructed. The specific nonlinear flux observer model can be shown in Equation 1 and Equation 2 above.

[0177] Construct load torque observer (ESO observer);

[0178] According to the mathematical model of the propeller, the load torque is estimated, and the extended state observer ESO is used to extract the load torque information. The specific observer model constructed can be shown in the above formula 5. By designing ESO to estimate the load torque as an extended amount, the estimated load information can be used to detect the working state of the propeller on the one hand, and on the other hand, it can be used to realize load torque feedback control.

[0179] Construct load torque control;

[0180] The current PI controller (i.e., current controller) is constructed using the method shown in equations 15 to 17 above.

[0181] The method shown in equation 9 above is adopted to construct a LADRC speed controller (i.e., rotation speed controller) using ESO to observe the disturbance in real time and perform disturbance compensation.

[0182] The load torque PI controller (i.e., load controller) is constructed using the method shown in the above formula 14. The underwater load of the thruster can be obtained through the ESO observer, and the load can be used to design the compensation of the speed loop. At the same time, the load information can be used to construct the thruster load controller, and the load information can be used as the feedback signal to construct the load feedback loop. The feedback loop control output signal is the speed command value, that is, the target speed, and the speed command value is input to the LADRC speed controller to achieve load regulation.

[0183] In the embodiment of the present invention, the speed control process of the underwater propeller can be as follows: Figure 3 As shown, it mainly includes:

[0184] During the operation of the propeller, the actual voltage signal and current signal of the propeller motor are collected, and the thrust command given by the upper control system (such as the shore-based PC) is received, and the current target thrust value is obtained from the thrust command. Based on the relationship shown in the above formula 13, the target load torque, that is, the load torque setting value, can be calculated based on the target thrust value. Using the pre-built nonlinear flux model (i.e., nonlinear flux observer), the motor rotor angle signal is observed, and the rotor speed signal can be obtained according to the rotor angle signal, thereby obtaining the propeller speed of the propeller, that is, the actual speed of the propeller, and the actual speed is used as the speed feedback signal for load torque observation and speed control. The ESO observer can estimate the current actual load torque value of the propeller based on the model shown in the above formula 5 and the relationship shown in formula 8, and use the actual load torque value as the load feedback signal for load control. The load controller can perform feedback control based on the current load torque setting value and the actual load torque value based on the control principle shown in the above formula 14, and output a speed setting signal, that is, the speed setting value (i.e., the target speed in the above text). The speed controller can output a corresponding current setting value (i.e., the target current in the above text) based on the speed setting value and the actual speed based on the control method shown in the above formula 9. The current controller can output a corresponding q-axis target voltage based on the control method shown in the above formula 17, combining the current setting value with the actual q-axis current in the current current signal, and use the q-axis target voltage to generate a voltage drive signal to control the speed of the thruster.

[0185] The embodiment of the present invention carries out corresponding tests on the method provided by the embodiment of the present invention in combination with actual parameters. The embodiment of the present invention adopts B-G431-ESC1 as the driving chip, and the electrical parameters of the thruster are as follows: resistance: 0.413Ohm, inductance: 7.50·10e-2mH, magnetic flux constant: 0.003Wb, moment of inertia: 2.07e-6Kgm^2, and number of magnetic pole pairs: 7.

[0186] The design of the current loop (current controller) depends on the resistance, inductance and actual current loop control frequency of the thruster motor. The current loop bandwidth is set to 2000, the current loop control frequency is 10K, and the parameters are designed as follows: K pq =0.15, K iq =826. In order to make ESO respond quickly, the execution frequency of the speed loop (speed controller) and ESO is designed to be 10K, and the bandwidth of ESO is designed to be w o =200, the proportional factor of the speed loop is designed to be: K pw =0.001.

[0187] The relationship between the underwater rotation speed, load torque and thrust of the propeller needs to be calibrated. In the embodiment of the present invention, when the propeller rotation speed is 3000 rpm / min, the thrust is about 18.0 N and the load torque is about 0.12 N·M.

[0188] The purpose of the load controller is to detect the working condition of the propeller. When the propeller is in a stalled state, the propeller load torque increases and the speed is zero. At this time, the propeller needs to be shut down in time. If a cavitation effect occurs, the load torque output of the propeller needs to be adjusted in time to reduce thrust loss and ensure smooth thrust output from shallow water to deep water. The PI design parameters of the load controller in the embodiment of the present invention are: K pt =10000, K it =50000, and its control frequency is 1K.

[0189] The embodiment of the present invention performs corresponding control tests based on the above parameter configuration. Figure 4 shows a schematic diagram of the control effect on current control, Figure 5 The schematic diagram of the control effect of speed control is shown. Figure 6 Figure 2 shows a schematic diagram of the control effect of load control. Figure 4 and Figure 5 In the figure, we can see that the thruster speed control scheme based on LADRC and nonlinear flux model can achieve better speed and current control. LADRC control can prevent the thruster from overshooting when working underwater, and because of the introduction of interference compensation, the response speed of the speed loop can be accelerated. Figure 6 The figure shows the control process of the load control instruction from -0.05N·M to 0.1N·M. In this process, the load controller achieves better load control by adjusting the speed output.

[0190] The method provided in the embodiment of the present invention can realize the speed control of the underwater thruster based on the FOC technology. Compared with the square wave control method, the motor power loss is lower, the motor pulsation can be reduced, and the control effect at low speed is better. The embodiment of the present invention adopts load feedback control, which can effectively improve the thrust loss problem of the thruster when working in shallow water. By adjusting the speed of the thruster to maintain the load unchanged, the thrust loss of the thruster can be effectively improved and the thrust output can be maintained stable. In the method provided in the embodiment of the present invention, the thruster speed and load can be observed, and the phenomena such as thruster stalling and runaway can be detected in real time to ensure the stable operation of the underwater robot.

[0191] and Figure 1 Corresponding to the speed control method of an underwater propeller shown in the figure, the embodiment of the present invention also provides a speed control device of an underwater propeller, which is used to Figure 1 The specific implementation of the method shown in is shown in the structural diagram Figure 7 As shown, including:

[0192] A signal acquisition unit 301 is used to acquire a voltage signal and a current signal corresponding to the underwater thruster;

[0193] A first determining unit 302 is used to determine an actual rotation speed corresponding to the underwater propeller according to the voltage signal and the current signal;

[0194] The torque estimation unit 303 is used to estimate the load torque of the underwater propeller based on the actual rotation speed to obtain the actual load torque corresponding to the underwater propeller;

[0195] A second determining unit 304 is used to determine a current target thrust value and determine a target load torque corresponding to the target thrust value;

[0196] A third determining unit 305 is used to determine a target speed according to the target load torque and the actual load torque;

[0197] A fourth determining unit 306, configured to determine a target current according to the actual speed and the target speed;

[0198] A fifth determining unit 307, configured to determine a voltage driving signal according to the target current and the current signal;

[0199] The rotation speed control unit 308 is used to control the rotation speed of the underwater thruster based on the voltage drive signal.

[0200] By using the device provided by the embodiment of the present invention, the actual speed and actual load torque of the propeller can be observed based on the real-time voltage signal and real-time current signal of the underwater propeller motor. The corresponding target current is determined in combination with the feedback of the actual speed and actual load torque of the propeller, and then the voltage drive signal is determined, thereby controlling the speed of the propeller. In the process of speed control, the speed can be feedback-controlled in combination with the actual load state of the propeller. When abnormal phenomena such as cavitation-like effect occur in the propeller, the thrust that matches the required thrust can be stably generated, so that the underwater robot can be maintained in the required posture and position, which is conducive to improving the accuracy and stability of motion control.

[0201] exist Figure 7 Based on the device shown, the device provided in the embodiment of the present invention can be further expanded into multiple units. The function of each unit can be found in the description of each embodiment provided in the previous text for the speed control method of the underwater propeller, and no further examples will be given here.

[0202] An embodiment of the present invention further provides a storage medium, which includes stored instructions, wherein when the instructions are executed, the device where the storage medium is located is controlled to execute the above-mentioned method for controlling the rotation speed of an underwater thruster.

[0203] The embodiment of the present invention further provides an electronic device, the structural diagram of which is shown in FIG. Figure 8 As shown, it specifically includes a memory 401 and one or more instructions 402, wherein the one or more instructions 402 are stored in the memory 401 and are configured to be executed by one or more processors 403 to perform the following operations:

[0204] Obtaining voltage signals and current signals corresponding to the underwater thruster;

[0205] Determining an actual rotation speed corresponding to the underwater propeller according to the voltage signal and the current signal;

[0206] Based on the actual rotation speed, estimating the load torque of the underwater propeller to obtain the actual load torque corresponding to the underwater propeller;

[0207] Determining a current target thrust value, and determining a target load torque corresponding to the target thrust value;

[0208] Determining a target speed according to the target load torque and the actual load torque;

[0209] Determining a target current according to the actual speed and the target speed;

[0210] Determining a voltage driving signal according to the target current and the current signal;

[0211] The rotation speed of the underwater thruster is controlled based on the voltage driving signal.

[0212] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can refer to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system or system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can refer to the partial description of the method embodiment. The system and system embodiments described above are merely schematic, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without creative work.

[0213] Professionals may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in the above description according to function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0214] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for controlling the rotation speed of an underwater propeller, characterized in that: include: Obtaining voltage signals and current signals corresponding to the underwater thruster; Determining an actual rotation speed corresponding to the underwater propeller according to the voltage signal and the current signal; Based on the actual rotation speed, estimating the load torque of the underwater propeller to obtain the actual load torque corresponding to the underwater propeller; Determining a current target thrust value, and determining a target load torque corresponding to the target thrust value; Determining a target speed according to the target load torque and the actual load torque; Determining a target current according to the actual speed and the target speed; Determining a voltage driving signal according to the target current and the current signal; The rotation speed of the underwater thruster is controlled based on the voltage driving signal.

2. The speed control method of an underwater propeller according to claim 1, characterized in that: The determining, based on the voltage signal and the current signal, an actual rotation speed corresponding to the underwater propeller comprises: Based on the voltage signal, the current signal and a pre-constructed nonlinear flux observer, a motor rotor angle signal is determined; the non-linear flux observer is an observer constructed based on the electrical parameters of the motor of the underwater thruster; Determine a rotor speed signal corresponding to the motor rotor angle signal; The rotor speed signal is speed-converted to obtain a propeller speed corresponding to the underwater propeller, and the propeller speed is used as an actual speed corresponding to the underwater propeller.

3. The speed control method of an underwater propeller according to claim 1, characterized in that: The estimating the load torque of the underwater propeller based on the actual rotation speed to obtain the actual load torque corresponding to the underwater propeller includes: Based on the actual rotation speed and a pre-constructed extended state observer, a real-time observation value of the load torque expansion state variable is determined; the extended state observer is an observer constructed based on the motor mechanical constant and the motor differential equation of the underwater propeller; Determining a load torque observation value based on the real-time observation value of the load torque expansion state variable; The load torque observation value is used as the actual load torque corresponding to the underwater thruster.

4. The speed control method of an underwater propeller according to claim 3, characterized in that: The step of determining the target current according to the actual rotation speed and the target rotation speed includes: Performing a difference operation on the target speed and the actual speed to obtain a first operation result; Performing a product operation on a preset proportional factor and the first operation result to obtain a second operation result; Obtaining magnetic flux parameters, magnetic pole pairs and moment of inertia corresponding to the underwater thruster; Performing a product operation on the moment of inertia and the real-time observed value of the load torque expansion state variable to obtain a third operation result; Performing a product operation on a preset constant, the flux linkage parameter and the number of magnetic pole pairs to obtain a fourth operation result; Dividing the third operation result by the fourth operation result to obtain a fifth operation result; The second operation result and the fifth operation result are summed, and the operation result is used as the target current.

5. The speed control method of an underwater propeller according to claim 1, characterized in that: The determining of the target load torque corresponding to the target thrust value comprises: Determine a propeller parameter set corresponding to the underwater propeller; the propeller parameter set includes a propeller torque coefficient, a propeller thrust coefficient and a propeller blade diameter; Based on the propeller parameter set, the target thrust value and a preset thrust-load torque function relationship, a load torque value corresponding to the target thrust value is calculated, and the load torque value corresponding to the target thrust value is used as the target load torque.

6. The speed control method of an underwater propeller according to claim 1, characterized in that: The determining of the target speed according to the target load torque and the actual load torque includes: Performing a difference operation on the target load torque and the actual load torque, and taking the operation result as the load torque difference; Performing an integration operation on the load torque difference to obtain a first integration result; Performing a product operation on a preset load loop integral term and the first integral result to obtain a sixth operation result; Performing a product operation on a preset load loop proportional term and the load torque difference to obtain a seventh operation result; A sum operation is performed on the sixth operation result and the seventh operation result, and the operation result is used as the target rotation speed.

7. The speed control method of an underwater propeller according to claim 1, characterized in that: The step of determining a voltage driving signal according to the target current and the current signal includes: Determine the actual q-axis current corresponding to the current signal; Performing a difference operation on the target current and the actual current of the q-axis, and taking the operation result as the current difference value; Performing an integration operation on the current difference to obtain a second integration result; Performing a product operation on a preset current loop proportional term and the current difference to obtain an eighth operation result; Performing a product operation on a preset current loop integral term and the second integral result to obtain a ninth operation result; performing a sum operation on the eighth operation result and the ninth operation result, and taking the operation result as the q-axis target voltage; The voltage drive signal is determined based on the q-axis target voltage.

8. A speed control device for an underwater propeller, characterized in that: include: A signal acquisition unit, used to acquire a voltage signal and a current signal corresponding to the underwater thruster; A first determining unit, configured to determine an actual rotation speed corresponding to the underwater propeller according to the voltage signal and the current signal; a torque estimation unit, configured to estimate the load torque of the underwater propeller based on the actual rotation speed, and obtain an actual load torque corresponding to the underwater propeller; A second determining unit, configured to determine a current target thrust value and a target load torque corresponding to the target thrust value; A third determining unit, configured to determine a target speed according to the target load torque and the actual load torque; a fourth determining unit, configured to determine a target current according to the actual speed and the target speed; a fifth determining unit, configured to determine a voltage driving signal according to the target current and the current signal; A rotation speed control unit is used to control the rotation speed of the underwater thruster based on the voltage drive signal.

9. A storage medium, characterized in that: The storage medium includes stored instructions, wherein when the instructions are executed, the device where the storage medium is located is controlled to execute the speed control method of the underwater propeller according to any one of claims 1 to 7.

10. An electronic device, characterized in that: It comprises a memory and one or more instructions, wherein the one or more instructions are stored in the memory and are configured to be executed by one or more processors to execute the speed control method of the underwater thruster as described in any one of claims 1 to 7.

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