阅读说明：本技术 一种无刷直流电机伺服系统扰动抑制与高精度跟踪控制方法 (Brushless direct current motor servo system disturbance suppression and high-precision tracking control method ) 是由 周兰 姜福喜 张铸 于 2020-07-09 设计创作，主要内容包括：本发明一种无刷直流电机伺服系统扰动抑制与高精度跟踪控制方法,其步骤包括：步骤S1：根据电压平衡方程和转矩平衡方程建立含有扰动的无刷直流电机伺服系统状态空间模型；步骤S2：根据无刷直流电机伺服系统状态空间模型设计降阶扩张状态观测器,实现对非匹配总扰动f(t,x<Sub>p</Sub>,M<Sub>c</Sub>)和电枢电流i(t)的实时估计；步骤S3：根据参考输入的周期性特征设计改进型重复控制器,构造周期性参考输入信号发生器；步骤S4：构建基于状态反馈控制器、扰动补偿器、重复控制器、前馈补偿器的复合控制器,同时实现伺服系统对非匹配扰动的有效抑制和对周期性参考输入的精确跟踪。本发明具有控制实现简单、跟踪精度高,同时鲁棒性能好等优点。(The invention discloses a brushless direct current motor servo system disturbance suppression and high-precision tracking control method, which comprises the following steps: step S1: establishing a state space model of a brushless direct current motor servo system containing disturbance according to a voltage balance equation and a torque balance equation; step S2: designing a reduced order extended state observer according to a state space model of a brushless direct current motor servo system to realize the non-matching total disturbance f (t, x) p ，M c ) And real-time estimation of armature current i (t); step S3: improved repetitive controller design based on periodic characteristics of reference input, constructionA periodic reference input signal generator; step S4: and a composite controller based on a state feedback controller, a disturbance compensator, a repetitive controller and a feedforward compensator is constructed, and meanwhile, the servo system can effectively suppress non-matching disturbance and accurately track periodic reference input. The invention has the advantages of simple control realization, high tracking precision, good robustness and the like.)

1. A brushless direct current motor servo system disturbance suppression and high-precision tracking control method is characterized by comprising the following steps:

step S1: establishing a state space model of a brushless direct current motor servo system containing disturbance according to a voltage balance equation and a torque balance equation;

step S2: designing a reduced order extended state observer according to a state space model of a brushless direct current motor servo system to realize the non-matching total disturbance f (t, x)_p，M_c) And real-time estimation of armature current i (t);

step S3: designing an improved repetitive controller according to the periodic characteristics of the reference input, and constructing a periodic reference input signal generator;

step S4: and a composite controller based on a state feedback controller, a disturbance compensator, a repetitive controller and a feedforward compensator is constructed, and meanwhile, the servo system can effectively suppress non-matching disturbance and accurately track periodic reference input.

2. The method for disturbance suppression and high-precision tracking control of a servo system of a brushless direct current motor according to claim 1, wherein in step S1, the step of establishing the state space model of the servo system includes:

step S101: the three-phase bridge type brushless direct current motor adopts a pairwise conduction mode, namely only two-phase armature windings are conducted at any time, and the third phase is suspended; assuming that a power device of a driving circuit is an ideal switch, the back electromotive force of a motor is a trapezoidal wave, the current of a fly-wheel diode is ignored, viscous damping is ignored, and a differential equation of a brushless direct current motor servo system can be obtained through voltage balance and torque balance:

wherein w (t) is the angular velocity of the motor, i (t) is the armature current, u (t) is the armature voltage, J is the moment of inertia of the motor rotor, L_sIs phase inductance, R is phase resistance, k_eIs the back electromotive force coefficient, p is the number of pole pairs of the motor, M_c(t) is the load torque; let J equal to J₀(1+ΔJ)，J₀Is the nominal value of the moment of inertia, and Δ J is the amount of panning.

Step S102: taking the state variable as x_p(t)＝[w(t) i(t)]^TThe system output is y_p(t) w (t), defining the total perturbation asEstablishing a brushless direct current motor servo system state space model:

whereinC_p＝[1 0]。

3. The method of claim 2, wherein the total disturbance f (t, x) is a total disturbance_p，M_c) And control input u (t) are not in the same channel and belong to non-matching disturbances.

4. The method for suppressing disturbance and tracking control with high precision of the brushless direct current motor servo system according to any one of claims 1 to 3, wherein in the step S2, the step of constructing the reduced order extended state observer includes:

step S201: defining an expanded state variable x₃(t)＝f(t，x_p，M_c) Is provided withThe state space model of the augmentation system is:

wherein:

step S202: state x₁(t) w (t) is system output, and the output rotating speed is obtained by accurately calculating a position signal of the Hall sensor; for current i (t) and total disturbance f (t, x)_p，M_c) Estimating, namely reducing an observer from a third order to a second order;

step S203: re-fetching state variablesControl inputOutput ofEstablishing a state space model of the reduced-order system:

wherein

Step S204: for the order-reduced system, the following observer is designed:

wherein z (t) ═ z₁(t) z₂(t)]^T，Are respectively a state x₂(t) i (t) and x₃(t)＝f(t，x_p，M_c) L is the observer gain matrix to be designed.

5. The method for disturbance suppression and high-precision tracking control of a brushless direct current motor servo system according to any one of claims 1 to 3, wherein in the step S3, the step of constructing the improved repetitive controller comprises:

step S301: let r (T) be a periodic reference input signal with a period of T, e (T) r (T) -y_p(t) is the tracking error; the improved repetitive controller is similar to a periodic signal generator and has the function of ensuring high-precision tracking of r (t); the time lag constant T is equal to the period of the reference input signal r (T); q(s) typically takes the first order low pass filter:

wherein w_cIs the shear frequency of the filter, determined by the operating frequency range of the system;

step S302: the low-pass filter satisfies the following frequency domain condition in the above step S301:

wherein w_rIs the maximum angular frequency of the periodic signal. In general, to achieve better control performance, the filter's shear frequency satisfies w_c≥5w_r。

6. The method for disturbance suppression and high-precision tracking control of a brushless direct current motor servo system according to any one of claims 1 to 3, wherein in step S4, the composite controller comprises a state feedback controller, a disturbance compensator, a repetitive controller and a feedforward compensator.

7. The method according to claim 6, wherein the state feedback controller and the feedforward compensator are used to stabilize the system and improve the dynamic response performance of the system; the disturbance compensator is used for effectively compensating the total non-matching and non-periodic disturbance and eliminating the influence of the disturbance on the system output; the repetitive control law is used for realizing high-precision tracking of the periodic reference signal.

8. The method for suppressing disturbance and tracking control of a brushless direct current motor servo system according to claim 6, wherein the composite controller is:

u(t)＝u₀(t)-K_x[x₁(t) z₁(t)]^T+K_dz₂(t)

repetitive control law u in composite controller₀(t)＝L^-1[K(s)V(s)]Where K(s) is the feedforward compensation gain, selecting either a PID controller or a lead-lag compensator; v(s) is a Laplace transform of the repetitive controller output upsilon (t); k_x＝[K_x1K_x2]Is the gain of the state feedback and,obtaining the position of the pole by a pole allocation method; k_dIs a disturbance compensation gain, and takes a disturbance compensation gain K_d＝-[C_p(A_p-B_uK_x)]^-1C_p(A_p-B_uK_x)^-1B_d(ii) a And the composite control law u (t) is used for ensuring the tracking performance and the disturbance suppression performance of the system at the same time.

Technical Field

The invention mainly relates to the technical field of motor control, in particular to a disturbance suppression and high-precision tracking control method for a brushless direct current motor servo system.

Background

The brushless direct current motor adopts the electronic commutator for commutation, not only keeps the good dynamic and static characteristics of the brush direct current motor, but also avoids the inherent defects brought by the electric brush commutator, and has the advantages of simple structure, high operating efficiency, large output torque and the like. Therefore, the method is widely applied to the fields of national defense, aerospace, automotive electronics, robots, industrial process control and the like.

In practical applications, a brushless dc motor servo system often needs to perform high-precision tracking on a periodic signal. The repetitive control based on the internal model principle is an effective method for solving the control problems, and the essence is that an internal model of periodic signals is implanted into a repetitive controller, the control input signal of the previous period is added into the control input of the period through a pure hysteresis positive feedback link, the control input of the period is regulated and generated, and the control input of the period is gradually performed in this way, and finally, the high-precision tracking or inhibition of signals of any period is realized. However, compared with the original feedback control system, the repetitive control system formed by introducing the repetitive controller improves the control performance of periodic signals, reduces the control performance of non-periodic signals (or periodic signals with periods different from the time lag constant of the repetitive controller), and cannot inhibit non-periodic disturbance. In the practical application process, uncertain factors such as internal parameter perturbation and external load disturbance inevitably exist in a brushless direct current motor servo system. In order to ensure the tracking performance of the repetitive control system on periodic signals, an effective and practical non-periodic disturbance compensation method must be found, the disturbance rejection performance of the repetitive control system is improved, and the robustness of the system is improved.

In order to solve the above problems, some researchers have proposed a sliding mode variable structure repetitive control method, an adaptive repetitive control method, and H_∞The control method is repeated. It is worth noting that these control methods mainly focus on the stability of the system, and they reduce the sensitivity of the disturbance on the system output channel by improving the robustness of the controller itself, thereby leading toThe system has a compromise problem between tracking control and disturbance suppression, nominal performance and robustness.

It is well known that feedforward compensation of disturbances is a very effective disturbance suppression method, but the premise for using this method is that all disturbances (including parametric perturbations of the system, unmodeled dynamics and external load disturbances, etc.) can be accurately measured directly by the sensors. Obviously, a practical control system cannot be installed with a large number of sensors to accurately measure all disturbances for cost reasons. Another important reason is that many disturbances are not even physical quantities and cannot be measured directly.

Therefore, another learner provides an active anti-interference method based on disturbance estimation and compensation, and the basic idea is to design an observer to estimate the real-time acting quantities of the uncertain factors and the disturbance, and then feed the estimated values back to the control input end through designing a compensator to perform dynamic compensation, so that the active suppression of the disturbance is realized, and the robustness of the servo system to the disturbance is improved. The existing active anti-interference method aiming at the non-periodic disturbance rejection of the repetitive control system mainly comprises a repetitive control method based on a disturbance observer, a repetitive control method based on linear active disturbance rejection and a repetitive control method based on an equivalent input disturbance estimator. The known information of the controlled object required by the linear active disturbance rejection method is minimum, and the controller design can be carried out only by knowing the relative order of the system. However, this method is only suitable for the system in which the controlled object is an integrator-cascade type. Another reason for severely restricting the application of linear active disturbance based repetitive control methods and disturbance observer based repetitive control methods is that in real systems disturbances often do not satisfy the matching condition, i.e. the disturbance and the control input are not in the same channel. Repetitive control systems based on equivalent input interference estimators are very demanding in terms of stability, and controllers that meet the stability condition may not be designed.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: aiming at the technical problems in the prior art, the invention provides a brushless direct current motor servo system disturbance suppression and high-precision tracking control method which is simple in control realization, high in tracking precision and good in robustness.

In order to solve the technical problems, the invention adopts the following technical scheme:

a brushless DC motor servo system disturbance suppression and high-precision tracking control method comprises the following steps:

step S1: establishing a state space model of a brushless direct current motor servo system containing disturbance according to a voltage balance equation and a torque balance equation;

step S2: designing a reduced order extended state observer according to a state space model of a brushless direct current motor servo system to realize the non-matching total disturbance f (t, x)_p，M_c) And real-time estimation of armature current i (t);

step S3: designing an improved repetitive controller according to the periodic characteristics of the reference input, and constructing a periodic reference input signal generator;

step S4: and a composite controller based on a state feedback controller, a disturbance compensator, a repetitive controller and a feedforward compensator is constructed, and meanwhile, the servo system can effectively suppress non-matching disturbance and accurately track periodic reference input.

As a further improvement of the process of the invention: in step S1, the step of establishing the state space model of the servo system includes:

step S101: the three-phase bridge type brushless direct current motor adopts a pairwise conduction mode, namely only two-phase armature windings are conducted at any time, and the third phase is suspended; assuming that a power device of a driving circuit is an ideal switch, the back electromotive force of a motor is a trapezoidal wave, the current of a fly-wheel diode is ignored, viscous damping is ignored, and a differential equation of a brushless direct current motor servo system can be obtained through voltage balance and torque balance:

where ω (t) is the angular velocity of the motor rotation, i (t) is the armature current, u (t) is the armature voltage, J is the moment of inertia of the motor rotor, and L_sIs phase inductance, R is phase resistance, k_eIn order to be a counter-electromotive force coefficient,p is the number of pole pairs of the motor, M_c(t) is the load torque; let J equal to J₀(1+ΔJ)，J₀Is the nominal value of the moment of inertia, and Δ J is the amount of panning.

Step S102: taking the state variable as x_p(t)＝[ω(t) i(t)]^TThe system output is y_p(t) w (t), defining the total perturbation asEstablishing a brushless direct current motor servo system state space model:

wherein

As a further improvement of the process of the invention: total disturbance f (t, x)_p，M_c) And control input u (t) are not in the same channel and belong to non-matching disturbances.

As a further improvement of the process of the invention: in step S2, the step of constructing the reduced order extended state observer includes:

step S201: defining an expanded state variable x₃(t)＝f(t，x_p，M_c) Is provided withThe state space model of the augmentation system is:

wherein:

step S202: state x₁(t) w (t) is system output, and the output rotating speed is obtained by accurately calculating a position signal of the Hall sensor; for the current i (t)) And total disturbance f (t, x)_p，M_c) Estimating, namely reducing an observer from a third order to a second order;

step S203: re-fetching state variablesControl inputOutput ofEstablishing a state space model of the reduced-order system:

wherein

Step S204: for the order-reduced system, the following observer is designed:

wherein z (t) ═ z₁(t) z₂(t)]^T，Are respectively a state x₂(t) i (t) and x₃(t)＝f(t，x_p，M_c) L is the observer gain matrix to be designed.

As a further improvement of the process of the invention: in step S3, the step of constructing the improved repetitive controller includes:

step S301: let r (T) be a periodic reference input signal with a period of T, e (T) r (T) -y_p(t) is the tracking error; the improved repetitive controller is similar to a periodic signal generator and has the function of ensuring high-precision tracking of r (t); time lag constant T and reference input signal r(t) are equal in period; q(s) typically takes the first order low pass filter:

wherein w_cIs the shear frequency of the filter, determined by the operating frequency range of the system;

step S302: the low-pass filter satisfies the following frequency domain condition in the above step S301:

wherein ω is_rIs the maximum angular frequency of the periodic signal. In general, to achieve better control performance, the filter's shear frequency satisfies w_c≥5ω_r。

As a further improvement of the process of the invention: in step S4, the composite controller includes a state feedback controller, a disturbance compensator, a repetitive controller, and a feedforward compensator.

As a further improvement of the process of the invention: the state feedback controller and the feedforward compensator are used for stabilizing the system and simultaneously improving the dynamic response performance of the system; the disturbance compensator is used for effectively compensating the total non-matching and non-periodic disturbance and eliminating the influence of the disturbance on the system output; the repetitive control law is used for realizing high-precision tracking of the periodic reference signal.

As a further improvement of the process of the invention: the composite controller is as follows:

u(t)＝u₀(t)-K_x[x₁(t) z₁(t)]^T+K_dz₂(t)

repetitive control law u in composite controller₀(t)＝L^-1[K(s)V(s)]Where K(s) is the feedforward compensation gain, selecting either a PID controller or a lead-lag compensator; v(s) is the Laplace transform of the repetitive controller output v (t); k_x＝[K_x1K_x2]The state feedback gain is obtained by a pole allocation method; k_dIs a disturbanceCompensating for gain by taking a disturbance compensation gain K_d＝-[C_p(A_p-B_uK_x)]^-1C_p(A_p-B_uK_x)^-1B_d(ii) a And the composite control law u (t) is used for ensuring the tracking performance and the disturbance suppression performance of the system at the same time.

Compared with the prior art, the invention has the advantages that:

1. the brushless direct current motor servo system disturbance suppression and high-precision tracking control method is simple in control implementation, high in tracking precision and good in robustness. The invention can simultaneously realize the effective suppression of the servo system to the non-matching disturbance and the accurate tracking to the periodic reference input by designing the reduced order extended state observer, the improved repetitive controller and the composite controller. Compared with the existing control method of the brushless direct current motor servo system, the method has the advantages that the reduced order extended state observer and the repetitive controller can be separately designed, and the flexibility is strong. The controller formed according to the method of the invention has simple structure, easy realization, strong robustness of the control system and high tracking control precision, and can meet the requirements of practical application on the anti-interference performance and the tracking performance.

2. The invention discloses a disturbance suppression and high-precision tracking control method for a brushless direct current motor servo system, which aims at solving the problems of non-matching interference such as internal parameter perturbation, external load disturbance and the like widely existing in the brushless direct current motor servo system, and designs a reduced order extended state observer under the condition that the output rotating speed can be directly measured by a sensor, so that the real-time estimation of current and total disturbance is realized. The disturbance compensator is utilized to realize effective suppression of total disturbance, a state feedback controller stabilizing system is designed, and the dynamic response speed of the system is improved. On the basis, the invention realizes accurate tracking of the periodic reference input by designing an improved repetitive controller. Therefore, the method provided by the invention is simple to realize, has less adjusting parameters, can realize the effective inhibition of the brushless direct current motor servo system on various disturbances and uncertainties and the high-precision tracking of periodic reference input, and meets the application requirements of the brushless direct current motor in the high-performance servo field.

Drawings

FIG. 1 is a schematic flow diagram of the present invention.

Fig. 2 is a schematic diagram of a brushless dc motor.

Fig. 3 is a structural block diagram of a control system of the brushless dc motor servo system disturbance suppression and high-precision tracking control method according to the present invention.

Fig. 4 is a real diagram of an experimental platform of a brushless dc motor servo system.

Fig. 5 is a block diagram of an experimental platform of a servo system of a brushless dc motor.

FIG. 6 is a diagram of the main computing subsystem and console subsystem connections.

FIG. 7 is a graph of reference input versus system output for an embodiment of the present invention using the control method of the present invention.

FIG. 8 is a system tracking error curve when the control method of the present invention is applied to the embodiment of the present invention.

FIG. 9 is a system control input curve when the control method of the present invention is applied to the embodiment of the present invention.

FIG. 10 is a comparison of tracking error for an embodiment of the present invention using the proposed control method of the present invention and a PID based repetitive control system; wherein (a) of fig. 10 is a system tracking error curve within 0 to 120 s; (b) the tracking error curve of the system is the tracking error curve of the system when the load is suddenly changed within 45-65 s; (c) is a system steady state tracking error curve in 80 to 100 s.

FIG. 11 is a comparison of tracking errors of an embodiment of the present invention using the proposed control method of the present invention and a linear active disturbance rejection based repetitive control system; wherein (a) of fig. 11 is a system tracking error curve within 0 to 120 s; (b) the tracking error curve of the system is the tracking error curve of the system when the load is suddenly changed within 45-65 s; (c) is a system steady state tracking error curve in 80 to 100 s.

FIG. 12 is a comparison of tracking errors of an embodiment of the present invention using the control method of the present invention and a repetitive control system based on a full-order extended state observer; wherein (a) of fig. 12 is a system tracking error curve within 0 to 120 s; (b) the tracking error curve of the system is the tracking error curve of the system when the load is suddenly changed within 45-65 s; graph (c) is a steady state tracking error curve for the system in 80 to 100 s.

Detailed Description

The invention will be described in further detail below with reference to the drawings and specific examples.

As shown in fig. 1, the method for suppressing disturbance and controlling high-precision tracking of a brushless dc motor servo system according to the present invention includes the steps of:

step S1: establishing a state space model of a brushless direct current motor servo system containing disturbance according to a voltage balance equation and a torque balance equation;

step S2: designing a reduced order extended state observer according to a state space model of a brushless direct current motor servo system to realize the non-matching total disturbance f (t, x)_p，M_c) And real-time estimation of armature current i (t);

step S3: designing an improved repetitive controller according to the periodic characteristics of the reference input, and constructing a periodic reference input signal generator;

step S4: and a composite controller based on a state feedback controller, a disturbance compensator, a repetitive controller and a feedforward compensator is constructed, and meanwhile, the servo system can effectively suppress non-matching disturbance and accurately track periodic reference input.

In a specific application example, in step S1, the establishing step of the state space model of the servo system may include:

step S101: referring to fig. 2, a schematic diagram of a brushless dc motor is shown. The three-phase bridge type brushless direct current motor adopts a pairwise conduction mode, namely only two-phase armature windings are conducted at any time, and the third phase is suspended. Assuming that a power device of a driving circuit is an ideal switch, the back electromotive force of a motor is a trapezoidal wave, the current of a fly-wheel diode is ignored, viscous damping is ignored, and a differential equation of a brushless direct current motor servo system can be obtained through voltage balance and torque balance:

wherein w (t) is the angular velocity of the motor, i (t) is the armature current, u (t) is the armature voltage, J is the moment of inertia of the motor rotor, L_sIs a phase inductance, R is a phase resistance,k_eis the back electromotive force coefficient, p is the number of pole pairs of the motor, M_c(t) is a load torque.

A plurality of uncertain factors exist in the actual motor operation process, wherein the uncertain factors comprise unmodeled dynamics, internal parameter perturbation, external load disturbance and the like. The invention mainly considers two conditions of disturbance of the rotational inertia parameter of the motor rotor caused by external load disturbance and load change. Let J equal to J₀(1+ΔJ)，J₀Is the nominal value of the moment of inertia, and Δ J is the amount of panning.

Step S102: taking the state variable as x_p(t)＝[ω(t) i(t)]^TThe system output is y_p(t) w (t), defining the total perturbation asEstablishing a brushless direct current motor servo system state space model:

wherein

The state space model of the brushless direct current motor servo system can be known as follows: total disturbance f (t, x)_p，M_c) And control input u (t) are not in the same channel and belong to non-matching disturbances.

In a specific application example, in step S2, the step of constructing the reduced order extended state observer includes:

step S201: defining an expanded state variable x₃(t)＝f(t，x_p，M_c) Is provided withThe state space model of the augmentation system is:

wherein:

through inspection, the original system can control and the system can be enlarged.

Step S202: for augmented systems, due to state x₁And (t) w (t) is the system output, and the output rotating speed can be accurately calculated by the position signal of the Hall sensor. It is therefore not necessary to construct the extended observer for state x₁Estimating (t) w (t) by only the current i (t) and the total disturbance f (t, x)_p，M_c) The estimation is carried out, and the observer can be reduced from three orders to two orders. The following is a reduced order extended state observer design.

For convenience of description, the matrix a is noted as:

separating measurable variables from non-measurable variables:

byCan obtain the productWherein the left side of the equal sign is measurable, and the right side of the equal sign is not measurable.

Is composed ofCan obtain the product The first term on the right of the equal sign is not measurable, and the second term on the right of the equal sign is measurable.

Step S203: re-fetching state variablesControl inputOutput ofEstablishing a state space model of the reduced-order system:

wherein

Through inspection, the order-reducing system can be observed.

Step S204: aiming at a reduced-order system state space model, the following observer is designed:

wherein z (t) ═ z₁(t) z₂(t)]^T，Are respectively a state x₂(t) i (t) and x₃(t)＝f(t，x_p，M_c) L is the observer gain matrix to be designed.

In the extended state observer due to reduced orderThe term contains the first derivative of the measured output rotating speed, the actual measurement signal often contains noise, and the derivative action can amplify the influence of the noise, so that the state equation of the reduced order extended state observer needs to be further transformed:

the reduced order extended state observer is written as:

wherein m (t) z (t) -Ly_p(t)，

In a specific application example, referring to fig. 3, a structural block diagram of a control system constructed according to the method of the present invention in a specific application example is shown. In step S3, the step of constructing the improved repetitive controller includes:

step S301: let r (T) be a periodic reference input signal with a period of T, e (T) r (T) -y_p(t) is a tracking error. The improved repetitive controller approximates a periodic signal generator, which functions to ensure high accuracy tracking of r (t). The time-lag constant T is equal to the period of the reference input signal r (T). For simplicity, q(s) usually takes the first order low pass filter:

wherein w_cIs the shear frequency of the filter, determined by the operating frequency range of the system.

Step S302: the low-pass filter satisfies the following frequency domain condition in the above step S301:

wherein ω is_rIs the maximum angular frequency of the periodic signal. Generally, to obtain better control performance, the shearing frequency of the filter satisfies wc ≧ 5 ω_r。

In a specific application example, in the step S4, the composite controller includes a state feedback controller, a disturbance compensator, a repetitive controller, and a feedforward compensator. The state feedback controller and the feedforward compensator are used for stabilizing the system and improving the dynamic response performance of the system; the disturbance compensator is used for effectively compensating the total non-matching and non-periodic disturbance and eliminating the influence of the disturbance on the system output; the repetitive control law is used for realizing high-precision tracking of the periodic reference signal.

The composite controller is designed as follows:

u(t)＝u₀(t)-K_x[x₁(t) z₁(t)]^T+K_dz₂(t)

repetitive control law u in composite controller₀(t)＝L^-1[K(s)V(s)]Where K(s) is the feedforward compensation gain, either a PID controller or a lead-lag compensator may be selected; v(s) is the Laplace transform of the repetitive controller output v (t); k_x＝[K_x1K_x2]The state feedback gain can be obtained by a pole allocation method; k_dIs a disturbance compensation gain, and takes a disturbance compensation gain K_d＝-[C_p(A_p-B_uK_x)]^-1C_p(A_p-B_uK_x)^-1B_d. And the composite control law u (t) simultaneously ensures the tracking performance and the disturbance suppression performance of the system.

From the above, the brushless dc motor servo system of the present invention includes a brushless dc motor, a magnetic powder brake, an RTLAB OP5600 real-time digital simulator, a motor driver board, and an upper computer. The control method comprises a reduced order extended state observer, an improved repetitive controller and a complex controller consisting of a state feedback controller and a disturbance compensator. The method utilizes a reduced order extended state observer to estimate armature current i (t) and non-matching total disturbance f (t, x) in real time_p，M_c) Estimate of the total disturbanceThe feedback is fed back to the disturbance compensator, so that various uncertainties and disturbances of the servo system are effectively suppressed, and the robustness of the system is enhanced. Measuring the rotation speed omega (t) and armature current estimated value of the motorThe feedback is fed back to the state feedback controller to stabilize the system and improve the dynamic response speed of the servo system. And an improved repetitive controller is added in a control loop, and high-precision tracking of the periodic reference signal is realized on the premise of system stabilization.

In order to verify the effectiveness of the control method provided by the invention under the actual working condition, in a specific application example, the invention builds a brushless direct current motor servo system disturbance suppression and high-precision tracking control experiment platform, such as an experiment platform object diagram shown in fig. 4. The experimental platform mainly comprises five parts: the system comprises a brushless direct current motor (rated voltage is 48V, rated power is 200W, rated rotating speed is 3000r/min), a magnetic powder brake (rated voltage is 24V, rated power is 12W), an RTLABOP5600 real-time digital simulator (comprising a CPU and an FPGA board card, a digital quantity and analog quantity I/O board card), a motor drive board (capable of driving a 24V-48V motor) and an upper computer.

Fig. 5 is a block diagram of an experimental platform of a servo system of a brushless dc motor. Three Hall sensors are embedded in the brushless direct current motor at intervals of 120 degrees, when the permanent magnet magnetic poles pass through, the Hall sensors can generate a group of three-digit binary position signals, and electronic commutation and real-time rotating speed measurement of the motor can be realized by utilizing the position signals. The magnetic powder brake is connected with a rotating shaft of the brushless direct current motor through a coupler and is used for receiving voltage output by an analog quantity output port of the RTLAB OP5600 real-time digital simulator to generate corresponding torque which is used as an external load to be applied to the rotating shaft of the motor. The OP5600 is used as a controller to receive a C language control program from an upper computer, and the C language control program generates a PWM control signal after being processed by the OP 5600. The motor drive board receives the PWM control signal and controls the on and off of a power device in the three-phase bridge circuit so as to realize the rotation of the motor.

The C language program implementation of the control algorithm of this example employs a model-based design Method (MBD). A control algorithm module, an analog quantity and digital quantity I/O interface module, a six-step reversing module, a Hall position signal speed measuring module, an overcurrent protection module, a signal monitoring module and the like are built in an MATLAB/Simulink environment, and the model is divided into a main computing subsystem and a console subsystem as shown in FIG. 6. All operation processes in the model are carried out in the main calculation subsystem, and all signal monitoring processes are carried out in the control console subsystem.

And loading the model into RTLAB software of an upper computer, compiling the model to automatically generate a C language control program, and downloading the C language control program into an RTLAB OP5600 real-time digital simulator for operation. The upper computer and the RTLAB OP5600 real-time digital simulator are communicated through a TCP/IP protocol, and all variables and online parameter adjustment can be monitored in real time through RTLAB upper computer software in the program running process.

In the embodiment, the disturbance suppression and high-precision tracking control method for the brushless direct current motor servo system is applied to the experimental platform of the brushless direct current motor servo system. The parameters of the experimental model S60BL-430 brushless dc motor are shown in table 1.

TABLE 1S 60BL-430 MODEL BRUSHLESS DC MOTOR PARAMETER TABLE

In the present example, the reference input signal is set to be r (t) ═ 1000+50cos (2 pi t), and the output torque (i.e. load torque) of the magnetic powder brake is set to be:

the pole of the reduced order extended state observer is configured to be [ -35 [ ]]And calculating to obtain an observer gain matrix L [ -0.1828-0.0620 [ -0.1828 [ ] -0.0620 [ ]]^T. The state feedback controller poles are configured to [ -15 [ ]]Calculating to obtain a state feedback gain K_x＝[-0.2552 56.6500]And a disturbance compensation gain K_d182.3246. The time lag constant T of the repetitive controller is 1s, and the cut-off frequency omega of the first-order low-pass filter_c100 Hz. The feedforward compensator K(s) adopts a PID controller, and the adjusting parameter is obtained

In order to prove the superiority of the brushless direct current motor servo system disturbance suppression and high-precision tracking control method, the three other control methods are respectively used for real-time control of the brushless direct current motor and are compared with the experimental results of the control method provided by the invention. All reference input signals, motor loads, observer poles, state feedback controller poles and other controller parameters in the comparison experiment are consistent with those in the experiment by adopting the control method provided by the invention.

FIG. 7 is a graph of a reference input versus a system output when the control method (RESO + PID + RC) of the present invention is applied to an embodiment of the present invention; FIG. 8 is a system tracking error curve when the control method of the present invention is applied to an embodiment of the present invention; FIG. 9 is a diagram illustrating the control input curves of the system when the control method of the present invention is applied to an embodiment of the present invention. The experimental result shows that the method can realize accurate estimation and effective compensation of the brushless direct current motor servo system on the total disturbance and ensure the high-precision tracking of the servo system on the periodic reference input.

FIG. 10 is a graph comparing tracking error of a PID based repetitive control (PID + RC) system using the control method of the present invention. Wherein (a) of fig. 10 is a system tracking error curve within 0 to 120 s; (b) the tracking error curve of the system is the tracking error curve of the system when the load is suddenly changed within 45-65 s; (c) is a system steady state tracking error curve in 80 to 100 s. The experimental result shows that the disturbance suppression performance of the control method provided by the invention is superior to that of PID-based repetitive control, and when the control method provided by the invention is adopted, the dynamic response speed of the system is higher, and the steady-state tracking error is smaller.

FIG. 11 is a graph comparing the tracking error of the system based on linear active disturbance rejection repetitive control (LADRC + PID + RC) and the control method of the present invention. Wherein (a) of fig. 11 is a system tracking error curve within 0 to 120 s; (b) the tracking error curve of the system is the tracking error curve of the system when the load is suddenly changed within 45-65 s; (c) is a system steady state tracking error curve in 80 to 100 s. The experimental result shows that the disturbance suppression performance of the reduced order extended state observer is superior to that of a linear active disturbance rejection method, and when the control method provided by the invention is adopted, the dynamic response speed of the system is higher, and the steady-state tracking error is smaller.

FIG. 12 is a graph showing the comparison of tracking errors between the control method of the present invention and a repetitive control (LADRC + PID + RC) system based on a full-order extended state observer according to an embodiment of the present invention. Wherein (a) of fig. 12 is a system tracking error curve within 0 to 120 s; (b) the tracking error curve of the system is the tracking error curve of the system when the load is suddenly changed within 45-65 s; graph (c) is a steady state tracking error curve for the system in 80 to 100 s. The experimental result shows that the disturbance suppression performance of the reduced-order extended state observer is superior to that of a full-order extended state observer, and when the control method provided by the invention is adopted, the dynamic response speed of the system is higher, and the steady-state tracking error is smaller.

The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above-mentioned embodiments, and all technical solutions belonging to the idea of the present invention belong to the protection scope of the present invention. It should be noted that modifications and embellishments within the scope of the invention may be made by those skilled in the art without departing from the principle of the invention.