An inertia identification method based on double-frequency sinusoidal speed command

Abstract

The application relates to the technical field of servo motor driving, and particularly discloses an inertia identification method based on double-frequency sinusoidal speed instructions, two different frequency sinusoidal speed instructions are sent to a motor by a servo driver, according to Newton's second law, a motion equation of a rotating system, a speed signal or an acceleration signal is multiplied by both sides of the motion equation of the rotating system, and integral operation is carried out in a complete period; for the test of the frequency omega1, the collected torque T e1 (t) is integrated with the acceleration, and thus the rotational inertia J can be directly solved. In the method, the speed instruction is a sinusoidal wave, compared with the trapezoidal acceleration and deceleration method and the step response method, the instruction is smoother, mechanical impact is small, and in addition, technical difficulties existing in the single-frequency sinusoidal excitation method can be avoided.

Description

Technical Field

[0001] This invention relates to the field of servo motor drive technology, and in particular to an inertia identification method based on dual-frequency sinusoidal speed commands. Background Technology

[0002] In modern industrial automation, the performance of AC servo systems directly affects the control accuracy and dynamic response of equipment. Moment of inertia, as a crucial parameter of servo systems, is essential for accurate controller parameter tuning.

[0003] In existing technologies, inertia identification methods mainly include: ① Trapezoidal acceleration / deceleration method: Calculates inertia by measuring torque and angular acceleration during acceleration, but is susceptible to frictional interference, especially nonlinear factors such as Coulomb friction and viscous friction; ② Step response method: Identifies based on the system's step response characteristics, but is sensitive to environmental noise and has weak anti-interference ability; ③ Single-frequency sinusoidal excitation method: Identifies using a single-frequency sine wave, but it is difficult to separate nonlinear factors, measurement accuracy decreases near the mechanical resonance point, requires multiple experiments, and is inefficient. Summary of the Invention

[0004] The purpose of this invention is to provide an inertia identification method based on dual-frequency sinusoidal speed commands to solve the problems encountered in the background art.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows: An inertia identification method based on dual-frequency sinusoidal velocity commands includes the following steps: S1. The servo driver sends two sinusoidal speed commands of different frequencies to the motor: , Taking the derivative of the velocity, we obtain the corresponding acceleration. , This step involves two sinusoidal speeds. , Differentiate it.

[0006] S2. According to Newton's second law, the equation of motion for the rotating system is: Formula 1 in: To output electromagnetic torque to the motor, Load torque, ; S3. Multiply both sides of equation 1 of the rotating system by the velocity signal. or acceleration signal and in a complete cycle Integral calculations are performed internally; for the test of frequency ω1, the collected torque T is used.e1 (t) and acceleration Perform integration; Formula 2 Since ω1(t) is a sine function, It is a cosine function. Based on the orthogonality property of trigonometric functions, the inertia term is calculated as follows: Formula 3 Eliminating the viscous friction term yields: Formula 4 In Equation 4, the sine and cosine are orthogonal, and the viscous friction term is eliminated.

[0007] Due to the approximation of the Coulomb friction term: Formula 5; In Equation 5, Coulomb friction is mainly in phase with velocity and orthogonal to acceleration, and its integral is approximately 0.

[0008] Based on the above orthogonality property, the original equation simplifies to: Formula 6; Therefore, the moment of inertia J can be directly solved: Formula 7 S4. Similarly, the inertia of the ω2(t) signal can be calculated and verified.

[0009] In the above scheme, as a preferred option, an algorithm for identifying the friction coefficient can also be calculated: make For frequency Below is the integral of the product of torque and speed: Formula 8 The first term represents the change in inertial energy: Formula 9 The second term represents viscous friction loss: Formula 10 The third term represents Coulomb friction loss: Formula 11 Equation 8 yields: + Formula 12 Similarly, the relationship under the ω2(t) signal can be derived; Formula 13 Formula 14 + Formula 15 By combining the relationships at the two frequencies, Equation 12 and Equation 15, it is possible to complete the... B Solve for it.

[0010] Formula 16 Formula 17 In the angular velocity sign function sign(w(t)), when w(t)>0, then sign(w(t)) = 1; when w(t) <0, then sign(w(t)) = -1; when w(t) = 0, then sign(w(t)) = 0.

[0011] Compared with the prior art, the beneficial effects of the present invention are: the inertia, viscous friction force and Coulomb friction force of the AC servo system are obtained by the dual-frequency sinusoidal speed command method. The speed command is a sine wave in the process. Compared with the trapezoidal acceleration and deceleration method and the step response method, the command is smoother and has less mechanical impact. In addition, it can avoid the technical difficulties of the single-frequency sinusoidal excitation method.

[0012] This method utilizes the orthogonality of physical quantities under sinusoidal excitation to effectively separate inertial and frictional effects, providing a theoretical basis for accurate measurement of rotational inertia. In practical applications, by acquiring torque and angular acceleration signals and combining them with integral calculations, the system's inertial, viscous friction, and Coulomb friction forces can be obtained. Attached Figure Description

[0013] The disclosure of this invention is illustrated with reference to the accompanying drawings. It should be understood that the drawings are for illustrative purposes only and are not intended to limit the scope of protection of this invention. In the drawings, the same reference numerals are used to refer to the same parts. Wherein: Figure 1 This is a timing flowchart of the identification method of the present invention. Detailed Implementation

[0014] To make the technical means, creative features, achieved objectives, and effects of this invention readily understandable, the invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the invention, and therefore only show the relevant components of the invention.

[0015] According to the technical solution of the present invention, without changing the essential spirit of the present invention, those skilled in the art can propose various interchangeable structural methods and implementations. Therefore, the following detailed embodiments and accompanying drawings are merely exemplary descriptions of the technical solution of the present invention, and should not be regarded as the entirety of the present invention or as a limitation or restriction of the technical solution of the present invention.

[0016] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0017] like Figure 1 As shown, an inertia identification method based on dual-frequency sinusoidal speed commands is proposed. According to this method, the nameplate of the tested motor is as follows: The nameplate of the aforementioned motor gives a rotational inertia value of 0.0096 kg·m². According to the inertia identification method based on dual-frequency sinusoidal velocity command disclosed in this scheme, the detection data is as follows: Substituting the feedback velocities w1fdb, Te1, w2fdb, Te2 under the two different frequency commands in the table above into equations 6, 7, 8, 9, 10, and 11, the total inertia J, viscous friction loss B, and Coulomb friction loss of the system can be calculated. .

[0018] Let A(w1fdb) be the magnitude of the w1fdb data. = A(w1fdb), frequency is , =Te1; retrieve the magnitude of the w2fdb data, where A(w2fdb) is the value of the w2fdb data. = A(w2fdb), frequency is , = Te2.

[0019] Substituting the data into equations 7, 16, and 17, we can identify J, B, and... .

[0020] The test results are as follows: Therefore, this method utilizes the orthogonality of various physical quantities under sinusoidal excitation to effectively separate inertial and frictional effects, providing a theoretical basis for accurate measurement of rotational inertia. In practical applications, by acquiring torque and angular acceleration signals and combining them with integral calculations, the system's inertial, viscous friction, and Coulomb friction forces can be obtained.

[0021] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An inertia identification method based on dual-frequency sinusoidal velocity commands, characterized in that, Includes the following steps: S1. The servo driver sends two sinusoidal speed commands of different frequencies to the motor: , ; Differentiating the velocity yields the corresponding acceleration. , ; S2. According to Newton's second law, the equation of motion for the rotating system is: Formula 1 in: To output electromagnetic torque to the motor, Load torque, ; S3. Multiply both sides of equation 1 of the rotating system by the velocity signal. or acceleration signal and in a complete cycle Integral calculations are performed internally; for the test of frequency ω1, the collected torque T is used. e1 (t) and acceleration Perform integration; Formula 2 Since ω1(t) is a sine function, It is a cosine function. Based on the orthogonality property of trigonometric functions, the inertia term is calculated as follows: Formula 3 Eliminating the viscous friction term yields: Formula 4 Due to the approximation of the Coulomb friction term: Formula 5; Based on the above orthogonality property, the original equation simplifies to: Formula 6; Therefore, the moment of inertia J can be directly solved: Formula 7 S4. Similarly, the inertia of the ω2(t) signal can be calculated and verified.

2. The inertia identification method based on dual-frequency sinusoidal velocity command according to claim 1, characterized in that: In step S2, the angular velocity sign function sign(w(t)) is: when w(t)>0, then sign(w(t)) = 1; when w(t) < 0, then sign(w(t)) = -1; when w(t) = 0, then sign(w(t)) = 0.

3. The inertia identification method based on dual-frequency sinusoidal velocity command according to claim 1, characterized in that: Based on step S3, a friction coefficient identification algorithm is also included: make For frequency Below is the integral of the product of torque and speed: Formula 8 The first term represents the change in inertial energy: Formula 9 The second term represents viscous friction loss: Formula 10 The third term represents Coulomb friction loss: Formula 11 Similarly, the relationship under the ω2(t) signal can be derived; By combining the relationships at two frequencies, it is possible to complete the... B. Solve for it.

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