Switching system control system and method based on TOD protocol and quantization constraint

Abstract

The invention relates to the field of control, and discloses a switching system control system and method based on a TOD protocol and quantization constraint, and the system comprises an actuator, a switching system, a sensor, a communication network with the TOD protocol and a quantizer, an observer, and a controller. The sensor is provided with a plurality of nodes, and each node is responsible for processing measurement output of the switching system; the communication network with the TOD protocol and the quantizer is used for scheduling sensor nodes and quantizing measurement output; the observer is used for estimating the system state according to the quantized measurement output and sending a corresponding state estimation value to the controller according to the switching signal; and the controller is used for generating control input according to the state estimation value, controlling the switching system and ensuring that the system has no large buffeting amplitude. According to the system and the method disclosed by the invention, the problem of system performance reduction caused by data transmission congestion in a communication network can be solved.

Description

Technical Field

[0001] The present invention relates to the field of control systems and control methods, and in particular to a switching system control system and method based on a TOD protocol and quantization constraints. Background Art

[0002] As an important and special hybrid system, the switching system has attracted much attention from the engineering community and control theory because it can describe the study of complex controlled objects and can be widely used in practical engineering. Generally speaking, a switching system consists of a finite number of continuous (discrete) time subsystems and a switching strategy that determines how the subsystems switch. The switching strategy is also called a switching signal or switching rule, which is represented by a piecewise constant function, and the continuous (discrete) time subsystem is generally represented by a differential (difference) equation.

[0003] In the past few decades, a large amount of research work has been focused on the study of switched systems. These studies have been motivated by the great potential of switched systems in various practical applications, including flight control systems, neural networks, and electronic circuits. It is worth noting that although various aspects of switched systems have been extensively explored, there is still a significant research gap in the study of switched systems for data transmission within communication networks, and thus the study of cyber-physical switched systems (CPSSs) remains a valuable and urgent challenge.

[0004] With the introduction of communication networks, signal quantization problems and sensor node collision problems also arise. In a network environment, due to the limited word length of data packets, signals are usually quantized before transmission. In the implementation process, the device or algorithm responsible for quantization is called a quantizer. It is worth noting that signal quantization is considered to be a key factor affecting the performance of CPSSs in existing research. In addition, multiple distributed sensors are embedded in the communication network, and only one communication channel is used at each sampling moment. If these sensor nodes are not effectively and reasonably scheduled, data transmission congestion will inevitably occur and CPSSs performance will be degraded. Nowadays, most research focuses on using Lyapunov functions to prove the stability of network control systems, but ignores how to effectively alleviate the problem of data transmission congestion. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a switching system control system and method based on the TOD protocol and quantization constraints, so as to achieve the purpose of solving the problem of system performance degradation caused by data transmission congestion in the communication network.

[0006] To achieve the above object, the technical solution of the present invention is as follows: A switching system control system based on a TOD protocol and quantization constraints, comprising an actuator, a switching system, a sensor, a communication network with a TOD protocol and a quantizer, an observer and a controller; The actuator is responsible for processing external disturbances and control inputs generated by the controller; The switching system is composed of a plurality of switching system modes and corresponding switching signals; The sensor has a plurality of nodes, each of which is responsible for processing the measurement output of the switching system; The communication network with the TOD protocol and quantizer is used to schedule the sensor nodes and quantize the measurement outputs, ensuring that the system does not suffer performance degradation due to data transmission congestion; The observer is used to estimate the system state according to the quantized measurement output, and send the corresponding state estimation value to the controller according to the switching signal; The controller is used to generate a control input according to the state estimation value, and control the switching system to ensure that the system does not have a large vibration amplitude.

[0007] A switching system control method based on the TOD protocol and quantization constraints, using the control system as described above, comprises the following steps: Step 1: The external disturbance enters the switching system after passing through the actuator. The sensor node collects the measurement output of the switching system and transmits the collected data to the communication network constrained by the TOD protocol. Step 2: In the communication network, the measurement output is quantized and constrained, and the TOD protocol is scheduled for the result after quantization and constraint, and the measurement output after passing through the communication network is obtained and transmitted to the observer; Step 3: The observer estimates the system state based on the measured output after passing through the communication network, and sends the corresponding state estimate to the controller according to the switching signal; In step 4, the controller solves for the observer gain, controller gain and average dwell time, and then generates a control input to control the switching system.

[0008] In the above scheme, in step 1, the external disturbance enters the switching system after passing through the actuator, and the sensor node collects the measurement output of the switching system to obtain the model of the switching system as follows: ; in, represents a time series, Represents the system status, represents the control input, represents the measurement output before entering the communication network, Represents the system output, represents the external disturbance, represents a nonlinear function; is a piecewise continuous function, called a switching signal, whose values ​​belong to a finite set , is the number of subsystems; when , , which means The subsystem is activated. , Respectively represent The switching point and Switching points; , , , , , and is the system matrix.

[0009] In the above scheme, in step 2, since there are multiple sensor nodes in the communication network, according to technical analysis, the system measurement output is expressed as follows: ; in, Before entering the communication network The measurement values ​​of sensor nodes, is the number of sensor nodes, ; The measured output after quantization constraints is: ; in, Indicates the measurement output To quantify constraints, represents the quantization level, Represents the measured output No. elements, function Represents rounding a number to the nearest integer; The quantization error is defined as .

[0010] In the above scheme, in step 2, based on the result of quantitative constraint on the measured output, the TOD protocol is introduced to schedule the sensor nodes. First, define For The sensor nodes that are allowed to access the communication network at any time are then scheduled by the TOD protocol. is represented as: ; in, Before entering the communication network The measurement values ​​of sensor nodes, Indicates that the sensor nodes after passing through the communication network exist The measured value at the moment, Indicates The weight matrix of sensor nodes; definition and , Can be rewritten as: ; in, represents the measurement value of the sensor node before entering the communication network, It means that the sensor nodes are The measured value at the moment, represents the weight matrix of the sensor node, as well as is the Kronecker product function, represents the identity matrix; After the quantization constraints and TOD protocol scheduling in the communication network, the measurement output after passing through the communication network is obtained: ; in, is the Kronecker product function.

[0011] In the above scheme, in step 3, the state estimation value is expressed as follows: ; in, Represents the system status exist The estimated value of the time, represents a nonlinear function, , , , is the system matrix; Represents the measurement output after passing through the communication network; and is the observer gain matrix.

[0012] In the above scheme, in step 4, the control input is as follows: ; in, Representatives in The control input at the moment, is the controller gain matrix.

[0013] Through the above technical solution, the switching system control system and method based on TOD protocol and quantization constraints provided by the present invention have the following beneficial effects: The present invention designs a control method for an information-physical switching system under the constraints of the Try-Once-Discard Protocol (TOD) and quantization effect. In a network environment, due to the limited word length of a data packet, the signal is usually quantized before transmission. After the quantization constraint processing, the TOD protocol is also required to effectively schedule the sensor nodes. The TOD protocol schedules the sensor nodes by using the argmax function selection principle. The TOD protocol stipulates that only one node can access the communication network at each moment, which will effectively alleviate the degradation of system performance caused by data transmission congestion caused by sensor node collision. Finally, the superiority and effectiveness of the method proposed in the present invention are verified by simulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] 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 are briefly introduced below.

[0015] Figure 1 Model for cyber-physical switching systems; Figure 2 Output results of the measurement after quantification and TOD protocol; Figure 3 A sensor node connected to a communication network; Figure 4 is the system state without quantization effect and TOD protocol constraints; Figure 5 is the system state under the constraints of quantization effect and TOD protocol; Figure 6 It is the system output without quantization effect and TOD protocol constraints; Figure 7 It is the system output under the constraints of quantization effect and TOD protocol. DETAILED DESCRIPTION

[0016] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0017] The present invention provides a switching system control system based on a TOD protocol and quantization constraints, comprising an actuator, a switching system, a sensor, a communication network with a TOD protocol and a quantizer, an observer, and a controller; The actuator is responsible for processing external disturbances and control inputs generated by the controller; The switching system is composed of a plurality of switching system modes and corresponding switching signals; The sensor has multiple nodes, each of which is responsible for processing the measurement output of the switching system; The communication network with TOD protocol and quantizer is used to schedule sensor nodes and quantize measurement outputs to ensure that the system does not suffer performance degradation due to data transmission congestion; The observer is used to estimate the system state according to the quantized measurement output, and send the corresponding state estimation value to the controller according to the switching signal; The controller is used to generate a control input according to the state estimation value, and control the switching system to ensure that the system does not have a large amplitude of chattering.

[0018] The present invention also discloses a switching system control method based on the TOD protocol and quantization constraints, which adopts the above control system and includes the following steps: Step 1: The external disturbance enters the switching system after passing through the actuator. The sensor node collects the measurement output of the switching system and transmits the collected data to the communication network constrained by the TOD protocol.

[0019] The external disturbance enters the switching system after passing through the actuator. The sensor node collects the measurement output of the switching system and obtains the model of the switching system as follows: ; in, represents a time series, Represents the system status, represents the control input, represents the measurement output before entering the communication network, Represents the system output, represents the external disturbance, represents a nonlinear function; is a piecewise continuous function, called a switching signal, whose values ​​belong to a finite set , is the number of subsystems; when , , which means The subsystem is activated. , Respectively represent The switching point and Switching points; , , , , , and is the system matrix.

[0020] Step 2: In the communication network, the measurement output is quantized and constrained, and the TOD protocol is scheduled for the result after quantization and constraint, and the measurement output after passing through the communication network is obtained and transmitted to the observer.

[0021] Since there are multiple sensor nodes in the communication network, according to technical analysis, the system measurement output is expressed as follows: ; in, Before entering the communication network The measurement values ​​of sensor nodes, is the number of sensor nodes, ; The measured output after quantization constraints is: ; in, Indicates the measurement output To quantify constraints, represents the quantization level, Represents the measured output No. elements, function Represents rounding a number to the nearest integer; The quantization error is defined as .

[0022] Based on the results of quantitative constraints on the measurement output, the TOD protocol is introduced to schedule the sensor nodes. First, we define For The sensor nodes that are allowed to access the communication network at any time are then scheduled by the TOD protocol. is represented as: ; in, Before entering the communication network The measurement values ​​of sensor nodes, Indicates that the sensor nodes after passing through the communication network exist The measured value at the moment, Indicates The weight matrix of sensor nodes; definition and ; Can be rewritten as: ; in, represents the measurement value of the sensor node before entering the communication network, It means that the sensor nodes are The measured value at the moment, represents the weight matrix of the sensor node, as well as is the Kronecker product function, represents the identity matrix; After the quantization constraints and TOD protocol scheduling in the communication network, the measurement output after passing through the communication network is obtained: ; in, is the Kronecker product function.

[0023] Step 3: The observer estimates the system state based on the measured output after passing through the communication network, and sends the corresponding state estimate to the controller according to the switching signal.

[0024] The state estimate is expressed as follows: ; in, Represents the system status exist The estimated value of the time, represents a nonlinear function, , , , is the system matrix; Represents the measurement output after passing through the communication network; and is the observer gain matrix.

[0025] In step 4, the controller solves for the observer gain, controller gain and average dwell time, and then generates a control input to control the switching system.

[0026] The control inputs are as follows: ; in, Representatives in The control input at the moment, is the controller gain matrix.

[0027] To make the controller generate control input To control the switching system, it is necessary to solve the observer gain, controller gain and average dwell time. The following linear matrix inequality is recommended: ; in, , , , , , , , , , , , , ; In the above linear matrix inequality, represents the submatrix solving for observer gain and controller gain, represents a sparse matrix of suitable dimensions, Represents when the switching signal is The measured output matrix of the subsystem activated at time, Represents the first The weight matrix of sensor nodes is represents the external perturbation matrix, Represents when the switching signal is The subsystem that is activated when The system matrix of sensor nodes is Represents when the switching signal is The control input matrix of the subsystem that is activated when represents a selection matrix with suitable dimensions, represents a sparse matrix of suitable dimensions, Represents when the switching signal is The subsystem that is activated when The measurement output matrix of sensor nodes, represents a selection matrix with suitable dimensions, represents a selection matrix with suitable dimensions, Represents when the switching signal is The subsystem that is activated when The observer gain matrix of the sensor nodes is: For The sensor nodes that are allowed to access the communication network at all times, called The switching signal at the moment, belongs to a set of positive integers , is a scalar constant ranging from 0 to 1. is a scalar constant greater than 1, Belongs to A scalar constant from 1 to 1, When the switching signal is The Lyapunov time-varying matrix of the subsystem activated at time , and is a positive definite matrix, , , , , , , , Represents system parameters, , , is a positive scalar constant, and It is The sensor nodes are connected to the communication network, and the switching signal is The observed gain of the subsystem activated when It is The sensor nodes are connected to the communication network, and the switching signal is The control gain of the subsystem activated at time represent A zero matrix of dimension , , Indicates The weight matrix of sensor nodes is represents the number of sensor nodes, The function represents a diagonal matrix, represents the identity matrix, as well as is the Kronecker product function, represent The identity matrix of dimension , represent A zero matrix of dimension , represent A zero matrix of dimension , represent A zero matrix of dimension , represent A zero matrix of dimension , represent A zero matrix of dimension , represent dimensional zero matrix.

[0028] By solving the above multiple linear matrix inequalities using the LMI toolbox in Matlab, the observer gain can be obtained and , controller gain , thereby obtaining the control input of the system and controlling the switching system.

[0029] The switching signal is used to control the switching between subsystems, bringing the above given parameters into In the equation, we can find the inequality Switching signal dwell time ,in is a scalar constant greater than 1, Belongs to A scalar constant from 1 to 1, is a scalar constant ranging from 0 to 1. Switching signal dwell time Take the nearest integer while satisfying the above inequality.

[0030] To verify the effectiveness and feasibility of the proposed method, by comparing the system states without quantization constraints and TOD protocol constraints and with quantization constraints and TOD protocol constraints, it can be found that although the system convergence speed is slowed down, the data transmission congestion phenomenon is greatly alleviated.

[0031] The present invention proposes the following two subsystems to verify the superiority and effectiveness of the proposed method: The following is the system matrix for subsystem 1 , , , , , , , and (Switching signal ): , , , , , , , , .

[0032] The following is the system matrix for subsystem 2 , , , , , , , and (Switching signal ): , , , , , , , , .

[0033] In order to verify the impact of quantization constraints and TOD protocol constraints on system performance, the present invention proposes two solutions, namely, a solution with quantization constraints and TOD protocol constraints and a solution without quantization constraints and TOD protocol constraints. For the solution without quantization constraints and TOD protocol constraints, set the parameters , , , , , , For the scheme with quantitative constraints and TOD protocol constraints, set the parameters , , , , , , , , , , . Substitute the above given parameters into In order to satisfy the inequality Switching signal dwell time In the present invention, the switching signal dwell time is taken .

[0034] By solving the linear matrix inequality to obtain the observer gain and controller gain and simulating the system state, the following results can be obtained: Observer gain under the scheme without quantization constraint and TOD protocol constraint , and controller gain , switching signal : , , , , , .

[0035] Observer gain under quantization constraint and TOD protocol constraint scheme , and controller gain , allowing sensor nodes to access the communication network , switching signal : , , , , , , , , , , , .

[0036] Figure 2 The measured output results after quantization and TOD protocol are shown. It can be seen from the figure that the measured output finally converges to the bounded value interval after 13 seconds of control turbulence, proving that the designed controller is effective and the measured output results are reasonable. In addition, Figure 2 As shown in the small figure in The residence time of the subsystem activated at .

[0037] Figure 3 The TOD protocol's selection problem for sensor nodes is demonstrated. From the figure, it can be seen that only one sensor node is selected to access the communication network at each moment, which will greatly alleviate the congestion and system performance degradation caused by data transmission.

[0038] Figure 4 and Figure 5 The system states without quantization constraints and TOD protocol constraints and the system states with quantization constraints and TOD protocol constraints are shown respectively. It can be seen from the figure that although the system state convergence speed is slightly slower after the introduction of quantization and TOD protocol, the data transmission congestion phenomenon is alleviated, and the primary data transmission task of the communication network control system is solved. In addition, Figure 4 and Figure 5 As shown in the small figure in The residence time of the subsystem activated at .

[0039] Figure 6 and Figure 7 The simulation results of the system output are shown. It can be seen from the figure that the system output eventually converges to a bounded value interval. In addition, Figure 6 and Figure 7 As shown in the small figure in The residence time of the subsystem activated at .

[0040] 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 switching system control system based on TOD protocol and quantization constraints, characterized in that: Includes actuators, switching systems, sensors, communication networks with TOD protocols and quantizers, observers, and controllers; The actuator is responsible for processing external disturbances and control inputs generated by the controller; The switching system is composed of a plurality of switching system modes and corresponding switching signals; The sensor has a plurality of nodes, each of which is responsible for processing the measurement output of the switching system; The communication network with the TOD protocol and quantizer is used to schedule the sensor nodes and quantize the measurement outputs, ensuring that the system does not suffer performance degradation due to data transmission congestion; The observer is used to estimate the system state according to the quantized measurement output, and send the corresponding state estimation value to the controller according to the switching signal; The controller is used to generate a control input according to the state estimation value, and control the switching system to ensure that the system does not have a large vibration amplitude.

2. A switching system control method based on TOD protocol and quantization constraints, using the control system as claimed in claim 1, characterized in that: The steps include: Step 1: The external disturbance enters the switching system after passing through the actuator. The sensor node collects the measurement output of the switching system and transmits the collected data to the communication network constrained by the TOD protocol. Step 2: In the communication network, the measurement output is quantized and constrained, and the TOD protocol is scheduled for the result after quantization and constraint, and the measurement output after passing through the communication network is obtained and transmitted to the observer; Step 3: The observer estimates the system state based on the measured output after passing through the communication network, and sends the corresponding state estimate to the controller according to the switching signal; In step 4, the controller solves for the observer gain, controller gain and average dwell time, and then generates a control input to control the switching system.

3. A switching system control method based on TOD protocol and quantization constraints according to claim 2, characterized in that: In step 1, the external disturbance enters the switching system after passing through the actuator, and the sensor node collects the measurement output of the switching system to obtain the model of the switching system as follows: ； in, represents a time series, Represents the system status, represents the control input, represents the measurement output before entering the communication network, Represents the system output, represents the external disturbance, represents a nonlinear function; is a piecewise continuous function, called a switching signal, whose values ​​belong to a finite set , is the number of subsystems; when , , which means The subsystem is activated. , Respectively represent The switching point and Switching points; , , , , , and is the system matrix.

4. A switching system control method based on TOD protocol and quantization constraints according to claim 2, characterized in that: In step 2, since there are multiple sensor nodes in the communication network, according to technical analysis, the system measurement output is expressed as follows: ； in, Before entering the communication network The measurement values ​​of sensor nodes, is the number of sensor nodes, ; The measured output after quantization constraints is: ； in, Indicates the measurement output To quantify constraints, represents the quantization level, Represents the measured output No. elements, function Represents rounding a number to the nearest integer; The quantization error is defined as .

5. A switching system control method based on TOD protocol and quantization constraints according to claim 4, characterized in that: In step 2, based on the results of quantitative constraints on the measured output, the TOD protocol is introduced to schedule the sensor nodes. First, define For The sensor nodes that are allowed to access the communication network at any time are then scheduled by the TOD protocol. is represented as: ； in, Before entering the communication network The measurement values ​​of sensor nodes, Indicates that the sensor nodes after passing through the communication network exist The measured value at the moment, Indicates The weight matrix of sensor nodes; definition and , Can be rewritten as: ； in, represents the measurement value of the sensor node before entering the communication network, It means that the sensor nodes are The measured value at the moment, represents the weight matrix of the sensor node, as well as is the Kronecker product function, represents the identity matrix, is the number of sensor nodes; After the quantization constraints and TOD protocol scheduling in the communication network, the measurement output after passing through the communication network is obtained: ； in, is the Kronecker product function.

6. A switching system control method based on TOD protocol and quantization constraints according to claim 2, characterized in that: In step 3, the state estimate is expressed as follows: ； in, Represents the system status exist The estimated value of the time, represents a nonlinear function, , , , is the system matrix; Represents the measurement output after passing through the communication network; and is the observer gain matrix.

7. A switching system control method based on TOD protocol and quantization constraints according to claim 6, characterized in that: In step 4, the control input is as follows: ； in, Representatives in The control input at the moment, is the controller gain matrix.

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