Method for inhibiting mechanical resonance of rocket projectile servo mechanism

Abstract

The invention discloses a method for suppressing mechanical resonance of a rocket projectile servo mechanism, which belongs to the field of servo control and mainly comprises the following steps: adding a damping generation module in a linear active-disturbance-rejection control algorithm; when it is detected that the servo mechanism reaches a target resonance position, the motion speed of the servo mechanism is detected through the damping generation module, and an input signal which is in direct proportion to the square of the motion acceleration of the servo mechanism and in the opposite direction is generated; and applying damping to the servo mechanism by using the input signal. The problem of mechanical resonance caused by insufficient rigidity of the servo structure can be solved under the condition that the dynamic performance is not sacrificed.

Description

Technical Field

[0001] The invention relates to the field of servo control, and in particular to a method for suppressing mechanical resonance of a rocket servo mechanism. Background Art

[0002] In rockets, due to limited volume, the servo mechanism usually adopts the form of motor + harmonic reducer + load. Due to the gap and flexibility of the transmission mechanism, the system itself has a certain resonant frequency, that is, the mechanical resonant frequency. Rockets have high speeds, so they require high bandwidth for their servo mechanisms. When the system bandwidth is close to or the same as the mechanical resonant frequency, the system will have obvious mechanical resonance, that is, the servo mechanism will have severe jitter near the target value. Mechanical resonance not only affects the performance of the servo mechanism, but may even damage the transmission device and burn the motor.

[0003] Mechanical resonance is generally suppressed through two aspects: mechanical design and control rate design. Mechanical design mainly reduces transmission clearance, improves transmission accuracy, and improves transmission stiffness by optimizing processes, materials, structural design, and other solutions. Control rate design is divided into active and passive aspects. The passive method is to reduce the system bandwidth by reducing the control gain or use notch filters / filters to remove the resonant frequency components. The active method is to improve the robustness of the system by modifying the system control structure, such as building an observer, using intelligent algorithms, etc., to resist the interference of mechanical resonance and avoid mechanical resonance.

[0004] Due to the difficulty in manufacturing and assembling high-precision machined parts, it is impossible to completely eliminate the transmission clearance in actual products. When designing products, the stiffness requirements are difficult to determine at the beginning of the project, and due to transmission wear, the transmission clearance of the machine itself is also increasing. Based on the above reasons, mechanical design can only reduce the probability of mechanical resonance, but cannot eliminate the occurrence of mechanical resonance. Therefore, in actual products, the control rate design method is often used to avoid mechanical resonance.

[0005] Passive suppression of resonance will reduce system performance. The most commonly used combination of PID + notch filter is used to suppress mechanical resonance in actual products. However, rockets require small size and high dynamic performance for servo mechanisms, and the dynamic performance margin of servo mechanisms is not large, so it is difficult to achieve this through this method. Active suppression of resonance is a hot topic in domestic and foreign academic research. There are two implementation methods: one is to use observers to achieve system pole matching, such as LADRC, but the effect is limited in practical applications; the other is to use more advanced control algorithms, such as model predictive control (MPC), but advanced algorithms rely on models, and it is difficult to accurately model the system in reality. In addition, the algorithm is complex to implement and difficult to deploy in industry. Summary of the invention

[0006] The purpose of the present invention is to overcome the technical problems existing in the prior art and provide a method for suppressing the mechanical resonance of a rocket servo mechanism.

[0007] The objective of the present invention is achieved through the following technical solutions:

[0008] A method for suppressing mechanical resonance of a rocket servo mechanism is provided, comprising:

[0009] Add a damping generation module to the linear active disturbance rejection control algorithm;

[0010] When it is detected that the servo mechanism reaches the target resonance position, the damping generation module is used to detect the movement speed of the servo mechanism, and an input signal which is proportional to the square of the movement acceleration of the servo mechanism and has an opposite direction is generated;

[0011] Damping is applied to the servomechanism using the input signal.

[0012] In some embodiments, adding a damping generation module to the linear active disturbance rejection control algorithm includes:

[0013] A damping generation module is added between the output of the original linear active disturbance rejection control algorithm and the servo mechanism. The damping generation module calculates a new output to the servo mechanism according to the output of the original linear active disturbance rejection control algorithm.

[0014] Preferably, the original linear active disturbance rejection control algorithm specifically includes:

[0015] 1) Tracking Differentiator:

[0016]

[0017] Where fhan is the fastest function, v1(k) is the output value at time k, v2(k) is the differential of v1 at time k, v(k) is the set value at time k, h is the interval time, V max Indicates the maximum speed;

[0018] The fastest function is specifically implemented as follows:

[0019]

[0020] In the formula, r represents the acceleration at time k;

[0021] 2) Linear combination:

[0022] e1(k)=v1(k)-z1(k)

[0023] e2(k)=v2(k)-z2(k)

[0024] u0(k)=kpe1(k)+kd e2(k)

[0025]

[0026] In the formula, k p , k d , b0 is the parameter of the linear combination that needs to be manually adjusted, u(k) is the output of the linear combination calculation, z1(k) and z2(k) are the outputs of the linear extended state observer;

[0027] 3) Linear Extended State Observer:

[0028]

[0029] In the formula, β1 and β2 are parameters that need to be adjusted, and y(k-1) represents the feedback value at time k-1.

[0030] Preferably, the algorithm of the damping generation module is as follows:

[0031]

[0032] Where k is the required debugging parameter, b is the PWM dead zone, out(t) is the input of the control object at time t, e1(t) represents the setting and feedback error at time t, flag is used to detect whether the set speed is greater than 0, D represents the feedback motion direction, and u is the output after ADRC calculation.

[0033] In some embodiments, applying damping to the servo mechanism using the input signal comprises:

[0034] Change the input voltage of the servo control system, increase the viscous friction coefficient of the servo control system through software simulation, and change the pole of the servo control system.

[0035] In some embodiments, it also includes:

[0036] A two-mass structure is used to dynamically model the transmission relationship of the servo control system.

[0037] It should be further explained that the technical features corresponding to the above options can be combined or replaced with each other to form a new technical solution if there is no conflict.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] (1) The present invention improves the linear ADRC algorithm by adding a damping generation module to the linear ADRC algorithm; when the servo mechanism is detected to have reached the target resonant position, the damping generation module is used to detect the movement speed of the servo mechanism and generate an input signal that is proportional to the movement speed of the servo mechanism and has the opposite direction; the input signal is used to apply damping to the servo mechanism, thereby changing the system poles so that the servo mechanism quickly stabilizes after reaching the target resonant position. The present invention can solve the problem of mechanical resonance caused by insufficient stiffness of the servo structure itself without sacrificing dynamic performance.

[0040] (2) The present invention improves the tracking differentiator in the LADRC to suppress overshoot and control the speed during movement.

[0041] (3) The present invention improves the robustness of the rudder system; the present invention is simple to implement, the parameters are easy to adjust, and it can be transplanted to other servo systems, and has universality and scalability. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 A diagram showing a two-mass body structure according to an embodiment of the present invention;

[0043] Figure 2 The structure diagram of the improved online active disturbance rejection control algorithm shown in the embodiment of the present invention;

[0044] Figure 3 The structure diagram of the existing online linear active disturbance rejection control algorithm shown in the embodiment of the present invention;

[0045] Figure 4 It is a comparison diagram of step feedback curves of the existing LADRC and the LADRC with the damping generation module added according to an embodiment of the present invention. DETAILED DESCRIPTION

[0046] The technical solution of the present invention is clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. The components of the embodiments of the present application described and shown in the accompanying drawings can be arranged and designed in various configurations. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0047] It should be noted that the defects existing in the solutions in the above-mentioned prior art are the results obtained by the inventor after practice and careful research. Therefore, the discovery process of the above-mentioned problems and the solutions proposed in the embodiments of the present application for the above-mentioned problems below should all be the contributions made by the inventor to the present application in the process of invention and creation, and should not be understood as technical contents known to technical personnel in this field.

[0048] In view of the technical problems pointed out in the background technology, the embodiments provided by the present invention are as follows:

[0049] In an exemplary embodiment, a method for suppressing mechanical resonance of a rocket servo mechanism is provided, comprising:

[0050] Add a damping generation module to the linear active disturbance rejection control algorithm;

[0051] When it is detected that the servo mechanism reaches the target resonance position, the damping generation module is used to detect the movement speed of the servo mechanism, and an input signal which is proportional to the square of the movement acceleration of the servo mechanism and has an opposite direction is generated;

[0052] Damping is applied to the servomechanism using the input signal.

[0053] Specifically, the present invention improves the existing linear anti-disturbance control algorithm. The damping generation module realizes system pole matching by changing the system damping. When a new control instruction sent by a host computer is received, the damping generation module is turned off, and the servo system follows the instruction action; when it is detected that the servo mechanism reaches the target resonant position, the damping generation module is turned on. The damping generation module detects the movement speed of the servo mechanism, generates a signal that is proportional to the servo mechanism speed and in the opposite direction, and inputs it to the servo mechanism, thereby simulating the damping received during the system movement process and achieving the effect of suppressing mechanical resonance.

[0054] The transmission relationship of the servo control system can usually be adopted as follows Figure 1 The two-mass structure shown in the figure is dynamically modeled, and the servo motor, screw, reducer and coupling are converted into the primary side equivalent inertia, recorded as J1; and the load is equivalent to the secondary side inertia, recorded as J2; K s and C s are the equivalent transmission stiffness and damping coefficient respectively; b is the equivalent transmission clearance.

[0055] B1 and B2 are the viscous friction coefficients on both sides respectively; T c1 and T c2 is the Coulomb friction torque on both sides; T e is the electromagnetic torque output by the motor; T s is the torsional moment of the shaft system, which is affected by the angle difference (θ1-θ2) and speed difference (ω1-ω2) between the primary and secondary sides. Without considering the effect of the gap, according to the principle of dynamics, we can get:

[0056]

[0057] According to the formula, the transfer function is:

[0058]

[0059] In actual working conditions, since the viscous friction coefficient is small, it can be ignored. The transfer function is as follows:

[0060]

[0061] According to the transfer function, the system has conjugate poles and its resonant frequency is:

[0062]

[0063] When damping is applied to the secondary side, the damping magnitude is Without considering the effect of the gap, according to the principle of dynamics, we can get:

[0064]

[0065] Ignoring the viscous friction coefficient, the transfer function is as follows:

[0066]

[0067] According to the transfer function, the system has conjugate poles and its resonant frequency is:

[0068]

[0069] According to the formula, adjusting k can adjust the system poles.

[0070] According to the motor torque equation:

[0071] T e =C M *i

[0072] In the formula, C M is the motor torque constant, i is the motor current, so changing the output current can increase the damping of the system.

[0073] According to the motor armature voltage balance equation:

[0074]

[0075] In the formula, C e is the motor potential constant, u is the input voltage, R is the motor resistance, and L is the motor inductance. According to the formula, when the speed remains unchanged, i reaches equilibrium, and at this time i is proportional to u.

[0076] In summary, by changing u, damping can be applied to the system. The direction is opposite to the servo mechanism movement speed.

[0077] Furthermore, the LADRC control algorithm is briefly introduced as follows:

[0078] The active disturbance rejection control algorithm is a control strategy that is more suitable for actual systems based on traditional PID control and combined with modern control theory knowledge. Since the active disturbance rejection controller (ADRC) has many parameters and is difficult to adjust, ADRC is linearized on this basis and a linear active disturbance rejection controller (LADRC) is proposed to simplify the adjustable parameters. The linear active disturbance rejection controller is more suitable for actual engineering. The LADRC control block diagram is shown below. Figure 3 shown.

[0079] The mathematical model of LADRC segmented control is as follows:

[0080] 1) Tracking Differentiator:

[0081]

[0082] fhan is the fastest function, and its specific implementation is as follows;

[0083]

[0084] In the formula, v1(k) represents the output value at time k, v2(k) is the differential of v1 at time k, v(k) represents the set value at time k, r represents the acceleration at time k, h represents the interval time, V max Indicates maximum speed.

[0085] 2) Linear combination

[0086]

[0087] u0(k)=kpe1(k)+kde2(k)

[0088]

[0089] In the formula, k p , k d , b0 are the parameters of the linear combination that need to be manually adjusted, u(k) is the output of the linear combination calculation, and z1(k) and z2(k) are the outputs of the linear extended state observer.

[0090] 3) Linear Extended State Observer

[0091]

[0092] In the formula, β1 and β2 are parameters that need to be adjusted, and y(k-1) represents the feedback value at time k-1.

[0093] Furthermore, the damping generation algorithm is designed as follows:

[0094] According to the transfer function, the system pole is related to the system viscous friction coefficient. Since the system viscous friction coefficient is small, the influence of this parameter is ignored in actual modeling. However, when the viscous friction coefficient is large enough, the influence of this parameter cannot be ignored. The damping generation algorithm simulates the influence of the viscous friction coefficient on the system, increases the viscous friction coefficient of the system, and then changes the system pole.

[0095] The overall control block diagram of LADRC after adding the damping generation algorithm is as follows: Figure 2 shown.

[0096] according to Figure 2 As shown in the figure, the LADRC related formula does not change. The output of LADRC does not act directly on the object, but on the damping generation module. The damping generation module calculates the new output to the object by collecting e1 in ADRC, Z2, Z3 and output u of the linear observer. Figure 2 The algorithm of the medium damping generation module is as follows:

[0097]

[0098] In the formula, k is the required debugging parameter, b is the PWM dead zone, out(t) is the input of the control object at time t, e1(t) represents the setting and feedback error at time t, flag is used to detect whether the setting speed is greater than 0, D represents the feedback motion direction, and u is the output after ADRC calculation. When e1(t) = 0, it means that the setting and feedback are equal at time t, indicating that the system has reached the target position at this time and the damping generation module needs to be turned on. The input of the control object at time t is equal to the square of the servo mechanism motion acceleration (Z3(t) 2 ) and the input signal in the opposite direction. Since the direction of the signal is opposite to the original motion direction, it hinders the movement of the mechanism, which is equivalent to the damping of the simulation system during movement, achieving pole matching and suppressing mechanical resonance. The signal can be adjusted by parameter k to adjust the system poles.

[0099] Furthermore, based on the improved algorithm above, a physical test was conducted, and the control effect is as follows:

[0100] The step feedback curves of the ordinary LADRC and the LADRC with the damping generation module algorithm added are tested using a servo mechanism platform. Figure 4 As shown in the figure, the servo mechanism using the ordinary LADRC control algorithm shakes violently after reaching the target position, while the servo mechanism using the LADRC control algorithm with the damping generation algorithm added stabilizes quickly after reaching the target position.

[0101] The above specific implementation methods are detailed descriptions of the present invention. It cannot be determined that the specific implementation methods of the present invention are limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions and substitutions can be made without departing from the concept of the present invention, which should be regarded as belonging to the protection scope of the present invention.

Claims

1. A method for suppressing mechanical resonance of a rocket servo mechanism, characterized in that: include: Add a damping generation module to the linear active disturbance rejection control algorithm; When it is detected that the servo mechanism reaches the target resonance position, the damping generation module is used to detect the movement speed of the servo mechanism, and an input signal which is proportional to the square of the movement acceleration of the servo mechanism and has an opposite direction is generated; Damping is applied to the servomechanism using the input signal.

2. The method for suppressing mechanical resonance of a rocket servo mechanism according to claim 1, characterized in that: The damping generation module is added to the linear active disturbance rejection control algorithm, including: A damping generation module is added between the output of the original linear active disturbance rejection control algorithm and the servo mechanism. The damping generation module calculates a new output to the servo mechanism according to the output of the original linear active disturbance rejection control algorithm.

3. The method for suppressing mechanical resonance of a rocket servo mechanism according to claim 2, characterized in that: The original linear active disturbance rejection control algorithm specifically includes: 1) Tracking Differentiator: In the formula, v1(k) represents the output value at time k, v2(k) represents the differential of v1 at time k, v(k) represents the set value at time k, h represents the interval time, V max Represents the maximum speed; the maximum speed function is specifically implemented as follows: In the formula, r represents the acceleration at time k; 2) Linear combination: u0(k)=kpe1(k)+k d e2(k) In the formula, k p , k d , b0 is the parameter of the linear combination that needs to be manually adjusted, u(k) is the output of the linear combination calculation, z1k, z2(k) are the outputs of the linear extended state observer; 3) Linear Extended State Observer: In the formula, β1 and β2 are parameters that need to be adjusted, and y(k-1) represents the feedback value at time k-1.

4. The method for suppressing mechanical resonance of a rocket servo mechanism according to claim 3, characterized in that: The algorithm of the damping generation module is as follows: Where k is the required debugging parameter, b is the PWM dead zone, out(t) is the input of the control object at time t, e1(t) represents the setting and feedback error at time t, flag is used to detect whether the set speed is greater than 0, D represents the feedback motion direction, and u is the output after ADRC calculation.

5. The method for suppressing mechanical resonance of a rocket servo mechanism according to claim 1, characterized in that: The applying damping to the servo mechanism by using the input signal comprises: Changing the input voltage of the servo control system simulates increasing the viscous friction coefficient of the servo control system and changing the pole of the servo control system.

6. The method for suppressing mechanical resonance of a rocket servo mechanism according to claim 1, characterized in that: Also includes: A two-mass structure is used to dynamically model the transmission relationship of the servo control system.

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