A Ship Trajectory Tracking System State Encoder and Its Encoding Method

Abstract

The present invention provides a system state encoder for a ship trajectory tracking system and its encoding method, which relates to the field of networked control technology. The system state encoder includes an information acquisition module, a state decoupling module, a primary encoding module, a secondary encoding module, a data encryption module, and a channel encoding module that are connected in sequence. The information acquisition module obtains the state sampling values of the ship trajectory tracking system from the state sensors, sends them to the state decoupling module, and performs state decoupling. The decoupled state variables are compressed and encoded by the primary encoding module, and then secondary encoded using the LZ encoding method. The generated codewords are sent to the data encryption module for data encryption, and finally, channel encoding is performed by the channel encoding module. The encoded codewords are sent to the transmitter to achieve effective information communication between the controlled ship and the management control system, ensuring the safe management and effective control of various ships in urban ports or sea lanes.

Description

Technical Field

[0001] The present invention relates to the technical field of networked control, and particularly relates to a state encoder for a ship trajectory tracking system and an encoding method thereof. Background Art

[0002] At present, the country vigorously develops the marine economy, including: marine shipbuilding industry, marine fishery, marine transportation industry, sea salt industry, marine oil and gas industry, coastal tourism industry, etc. In 2021, the total volume of China's marine economy reached 9,038.5 billion yuan, exceeding 9 trillion yuan, with a year-on-year growth of 8.3%, accounting for 15.0% of the gross regional product of coastal areas. A large number of various types of ships are used in the marine economy. For example, passenger ships, general cargo ships, container ships, timber ships, ro-ro ships, bulk grain ships, coal ships, oil tankers, refrigerated ships, liquefied gas ships, liquid chemical ships, salvage ships, sea rescue ships, icebreakers, cable laying ships, scientific research ships, fishing boats, etc. The navigation safety and effective management of various ships have currently become a key technical issue attracting wide attention.

[0003] The ship traffic management system is an effective management service provided to ensure the navigation safety of various ships in ports or waterways and improve the navigation efficiency. In the ship traffic management system, the ship trajectory tracking system plays an important role and is the key guarantee for realizing the navigation safety and effective management of various ships. The ship trajectory tracking system applies Internet of Things technology, artificial intelligence technology, networked control technology, Beidou positioning and navigation technology, etc. to the navigation trajectory tracking and control of various ships, and has achieved remarkable results.

[0004] In some urban ports or sea waterways, due to factors such as a large number of ships, narrow waterways, and strong external winds and waves, the difficulty of ship trajectory tracking and control increases. Especially due to limited communication bandwidth, the information exchange between ships and between ships and the onshore traffic management system is restricted, which greatly affects the normal operation of the ship trajectory tracking system and may seriously cause problems such as ship collisions and deviation from the waterway.

[0005] Therefore, in the case of limited communication bandwidth, how to design a state encoder for a ship trajectory tracking system, adopt an effective encoding method, reduce the influence of factors such as a large number of ships, narrow waterways, and strong external winds and waves, and ensure the navigation safety and effective management of ships is indeed one of the key technical problems that need to be solved currently. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a state encoder for a ship trajectory tracking system and its encoding method in view of the deficiencies of the above-mentioned prior art, which can realize the state encoding of the ship trajectory tracking system under limited communication bandwidth, effectively reduce the influence of noise and interference in the wireless communication channel, realize the effective information communication between the controlled ship and the management control system, and ensure the safe management and effective control of various ships in urban ports or sea lanes.

[0007] To solve the above technical problem, the technical solution adopted by the present invention is as follows:

[0008] On the one hand, the present invention provides a state encoder for a ship trajectory tracking system, including an information acquisition module, a state decoupling module, a primary encoding module, a secondary encoding module, a data encryption module, and a channel encoding module that are connected in sequence;

[0009] The information acquisition module is used to obtain the state sampling value D(k) of the ship trajectory tracking system from the state sensor;

[0010] The state decoupling module is used to establish a system state equation based on the dynamic characteristics of the ship trajectory tracking system, perform state decoupling, and send the decoupled ship trajectory tracking system state equation and the decoupled ship trajectory tracking system state to the primary encoding module;

[0011] The primary encoding module is used to perform primary encoding on the n state variables of the decoupled ship trajectory tracking system state to calculate the corresponding binary equal-length codewords c1(k), c2(k),..., c n (k), and send the binary equal-length codewords c1(k), c2(k),..., c n (k) to the secondary encoding module;

[0012] The secondary encoding module is used to merge c1(k), c2(k),..., c n (k) into a binary sequence with a length of L(k), perform secondary encoding on it using the LZ encoding method to generate a codeword C(k), and send the generated codeword C(k) to the data encryption module;

[0013] The data encryption module is used to perform data encryption on the codeword C(k) using the DES cryptographic algorithm to generate a binary sequence G(k) with a length of L(k), and send G(k) to the channel encoding module;

[0014] The channel encoding module is used to perform channel encoding on the binary sequence G(k) using the encoding method of binary (N(k), L(k)) Hamming code, and send the generated codeword after encoding to the transmitter.

[0015] Further, the information acquisition module sets the sampling time of the ship trajectory tracking system state to h seconds, and obtains the ship trajectory tracking system state sampling value from the state sensor every h seconds; the ship trajectory tracking system state sampling value at the k-th moment is set as D(k) ∈ R n , D(k) = [d1(k) d2(k)…d n (k)] T ; where d i (k) ∈ R represents the i-th state variable at the k-th moment; there are n state variables of the ship trajectory tracking system to be transmitted to the management and control system at the k-th moment;

[0016] The information acquisition module stores the ship trajectory tracking system state sampling value D(k) at each moment and sends it to the state decoupling module.

[0017] Further, the specific method for the state decoupling module to perform decoupling is as follows:

[0018] Based on the dynamic characteristics of the ship trajectory tracking system, establish the system state equation as follows:

[0019] D(k + 1) = AD(k) + BU(k) + FW(k)

[0020] where U(k) ∈ R p is the control output of the management and control system; W(k) ∈ R q is the noise and interference generated in the ship trajectory tracking system; A, B, and F are multi-dimensional numerical matrices, and their values are determined by the ship type and control strategy;

[0021] There exists a non-singular matrix H with real number values. Set the transformation matrix M as:

[0022]

[0023] where m i ∈ R, i = 1, 2,..., n;

[0024] represents the decoupled system state value, as shown in the following formula:

[0025]

[0026] The decoupled ship trajectory tracking system state equation is transformed into:

[0027]

[0028] Set:

[0029] HBU(k) = [u1(k)u2(k)…u n (k)] T

[0030] HFW(k) = [w1(k) w2(k) … w n (k)] T

[0031] Let represent the i-th state variable of the decoupled ship trajectory tracking system at time k, then we get:

[0032]

[0033] Then the state of the decoupled ship trajectory tracking system is shown as follows:

[0034]

[0035] The state decoupling module sends the state equation of the decoupled ship trajectory tracking system and the state of the ship trajectory tracking system to the primary coding module.

[0036] Furthermore, the primary coding module obtains the state equation of the decoupled ship trajectory tracking system and the state of the decoupled ship trajectory tracking system from the state decoupling module and performs primary coding on as follows:

[0037] Update and calculate the state bound γ (k) of the i-th decoupled ship trajectory tracking system state variable at time k; i (k);

[0038] Let and γ i (k) represent the compressed state prediction value and state bound of the i-th decoupled ship trajectory tracking system state variable at time k respectively, then we have:

[0039]

[0040] where γ i (k) changes with time and needs to be recalculated before each coding. The calculation method is as follows:

[0041]

[0042] where represents the upper bound of the value of w i (k); n i represents the compression parameter used when quantifying ;

[0043] ​Set the state variables of the decoupled ship trajectory tracking system The compression parameter n i and calculate the predicted value of the compressed state The compression parameter n i is calculated as follows:

[0044]

[0045] where |·| represents the absolute value symbol, represents the ceiling function.

[0046] Calculate the predicted value of the compressed state of the state variables of the decoupled ship trajectory tracking system The calculation method is as follows: The calculation method is as follows:

[0047]

[0048] where represents the compressed state value of the i-th state variable of the decoupled ship trajectory tracking system at the (k - 1)th moment ;

[0049] Based on the updated state bound γ i (k), the compression parameter n i and the predicted value of the compressed state calculate the compressed state value of the state variables of the decoupled ship trajectory tracking system Let represent the predicted error value of the compressed state of the state variables of the decoupled ship trajectory tracking system and its calculation method is as follows:

[0050]

[0051] Divide the interval (-γ i (k), γ i (k)) into n i equal subintervals as follows:

[0052]

[0053] Observe the predicted error value of the compressed state of the state variables of the decoupled ship trajectory tracking system to determine which of the above n i subintervals it is in. Then, the midpoint value of the corresponding subinterval is set as the compressed state value of the state variables of the decoupled ship trajectory tracking system

[0054] For the state variables of the decoupled ship trajectory tracking system of the compressed state value Perform encoding, calculate the corresponding binary equal-length codeword c i (k); Divide the interval (-γ i (k), γ i (k)) into n i equal subintervals and number them: The r-th subinterval is numbered r; Let l i (k) represent the length of the binary equal-length codeword c i (k), and the calculation method is as follows:

[0055]

[0056] Observe the compressed state prediction error value of the state variables of the decoupled ship trajectory tracking system If it is located in which of the n subintervals, then convert the corresponding subinterval number r into a binary number with a length of l i (k), and this binary number is the binary equal-length codeword c i (k); i (k);

[0057] The primary encoding module sends the binary equal-length codeword c i (k) to the secondary encoding module.

[0058] Furthermore, after obtaining the binary equal-length codeword c i (k) from the primary encoding module, the secondary encoding module combines c1(k), c2(k), …, c n (k) into a binary sequence with a length of L(k), and performs secondary encoding on it using the LZ encoding method to generate the codeword C(k); The calculation formula for the length L(k) is as follows:

[0059]

[0060] The secondary encoding module sends the generated codeword C(k) to the data encryption module.

[0061] On the other hand, the present invention also provides a ship trajectory tracking system state encoding method, which is implemented by using the above ship trajectory tracking system state encoder, and includes the following steps:

[0062] Step 1: The information acquisition module obtains the ship trajectory tracking system state sampling value D(k) from the state sensor;

[0063] Step 2: The state decoupling module decouples the ship trajectory tracking system state sampling value D(k), and the decoupled ship trajectory tracking system state Provided to the primary encoding module for encoding;

[0064] Step 3: The primary encoding module performs primary encoding on the n state components of, and calculates the corresponding binary equal-length codewords c1(k), c2(k), …, c n (k), and sends the binary equal-length codewords c1(k), c2(k), …, c n (k) to the secondary encoding module;

[0065] Step 4: The secondary encoding module combines c1(k), c2(k), …, c n (k) into a binary sequence of length L(k), and performs secondary encoding on it using the LZ encoding method to generate a codeword C(k), and sends the generated codeword C(k) to the data encryption module;

[0066] Step 5: The data encryption module obtains the generated codeword C(k) from the secondary encoding module, and uses the DES cryptographic algorithm to encrypt the data, generating a binary sequence G(k) of length L(k), and sends G(k) to the channel encoding module;

[0067] Step 6: The channel encoding module uses the encoding method of binary (N(k), L(k)) Hamming code to perform channel encoding on the binary sequence G(k), and sends the generated codeword after encoding to the transmitter.

[0068] Furthermore, in Step 1, the information acquisition module sets the sampling time of the ship trajectory tracking system state to h seconds, and obtains the ship trajectory tracking system state value from the state sensor every h seconds; the ship trajectory tracking system state sampling value at the k-th moment is set as D(k) ∈ R n ; D(k) = [d1(k) d2(k) … d n (k)] T ; where, d i (k) ∈ R represents the i-th state variable at the k-th moment; there are n state variables of the ship trajectory tracking system to be transmitted to the management control system at the k-th moment;

[0069] The ship trajectory tracking system state sampling value D(k) at each moment is stored and sent to the state decoupling module.

[0070] Furthermore, the specific method of Step 2 is as follows:

[0071] Step 2.1: Based on the dynamic characteristics of the ship trajectory tracking system, establish the system state equation as follows:

[0072] D(k + 1) = AD(k) + BU(k) + FW(k)

[0073] where \(U(k)\in\mathbb{R}\) p is the control output of the management control system; \(W(k)\in\mathbb{R}\) q is the noise and interference generated in the ship trajectory tracking system; \(A\), \(B\), \(F\) are multi-dimensional numerical matrices, and their values are determined by the ship type and control strategy;

[0074] Step 2.2: Calculate the transformation matrix;

[0075] There exists a non-singular matrix \(H\) with real number values, and the transformation matrix \(M\) is set as:

[0076]

[0077] where \(m\) i \(\in\mathbb{R}\), \(i = 1, 2, \cdots, n\);

[0078] Step 2.3: Calculate the decoupled state equation;

[0079] Denotes the decoupled system state, as shown in the following equation:

[0080]

[0081] The state equation of the decoupled ship trajectory tracking system is transformed into:

[0082]

[0083] Step 2.4: Calculate the state of the decoupled ship trajectory tracking system;

[0084] Set:

[0085] \(HBU(k)=[u_1(k)\ u_2(k)\cdots u\) n (k)] T

[0086] \(HFW(k)=[w_1(k)\ w_2(k)\cdots w\) n (k)] T

[0087] For the state of the decoupled ship trajectory tracking system at any time \(k\) of the \(i\)-th state variable Then we get:

[0088]

[0089] Then the state of the decoupled ship trajectory tracking system is as shown in the following equation:

[0090]

[0091] The state decoupling module sends the decoupled state equation of the ship trajectory tracking system and the decoupled state to the primary coding module.

[0092] Furthermore, the specific method for step 3 is as follows:

[0093] Step 3.1: Update and calculate the state bound γ (k) of the i-th decoupled state variable of the ship trajectory tracking system at time k: i (k):

[0094] Let and γ i (k) represent the compressed state prediction value and the state bound of the i-th decoupled state variable of the ship trajectory tracking system at time k, respectively. Then, we have:

[0095]

[0096] where γ i (k) changes with time and needs to be recalculated before each coding. The calculation method is as follows:

[0097]

[0098] where represents the upper bound of the value of wi(k); n i represents the compression parameter used for quantifying ;

[0099] Step 3.2: Set the compression parameter n of the decoupled state variable of the ship trajectory tracking system and calculate the compressed state prediction value i

[0100] The calculation method of the compression parameter n i is as follows:

[0101]

[0102] where |·| represents the absolute value symbol, represents the ceiling function.

[0103] Calculate the compressed state prediction value of the decoupled state variable of the ship trajectory tracking system The calculation method is as follows:

[0104]

[0105] where ​​Denote the state variable of the decoupled ship trajectory tracking system at the (k - 1)th moment of the compressed state value;

[0106] Step 3.3: Based on the updated and calculated state bound γ i (k), compression parameter n i and the predicted value of the compressed state calculate the state variable of the decoupled ship trajectory tracking system of the compressed state value

[0107] Let denote the predicted error value of the compressed state of the state variable of the decoupled ship trajectory tracking system , and the calculation method is as follows:

[0108]

[0109] Divide the interval (-γ i (k), γ i (k)) into n i equal sub - intervals as follows:

[0110]

[0111] Observe the predicted error value of the compressed state of the state variable of the decoupled ship trajectory tracking system , and if it is located in one of the above n sub - intervals, then the mid - point value of the corresponding sub - interval is set as the compressed state value of the state variable of the decoupled ship trajectory tracking system i of the compressed state value

[0112] Step 3.4: Encode the compressed state value of the state variable of the decoupled ship trajectory tracking system to calculate the corresponding binary equal - length codeword c i (k);

[0113] Divide the n i equal sub - intervals obtained by dividing the interval (-γ i (k), γ i (k)): The r - th sub - interval is numbered r;

[0114] Let l i (k) denote the length of the binary equal - length codeword c i (k), and the calculation method is as follows:

[0115] l i (k) = ⌈log₂n i ​

[0116] Observed state variables of the ship trajectory tracking system after decoupling Compressed state prediction error value Located in the n i Which small interval among the small intervals, then convert the number r of the corresponding small interval into a binary number with a length of l i (k), and this binary number is the binary equal-length codeword c i (k).

[0117] Furthermore, in step 4, the calculation formula of the length L(k) is as follows:

[0118]

[0119] The beneficial effects of adopting the above technical solutions are as follows: The state encoder and its encoding method of the ship trajectory tracking system provided by the present invention are mainly applicable to the ship trajectory tracking system, and are particularly suitable for state encoding of the ship trajectory tracking system under the condition of limited communication bandwidth. It can effectively reduce the influence of noise and interference in the wireless communication channel, improve the encoding efficiency, realize the effective information communication between the controlled ship and the management control system, and ensure the safe management and effective control of various ships in urban ports or sea lanes. Description of the Drawings

[0120] Figure 1 Schematic diagram of the structure of the ship trajectory tracking system provided by the embodiment of the present invention;

[0121] Figure 2 Block diagram of the structure of the state encoder of the ship trajectory tracking system provided by the embodiment of the present invention;

[0122] Figure 3 Schematic diagram of the principle of the state decoupling module provided by the embodiment of the present invention;

[0123] Figure 4 Schematic diagram of the principle of the primary encoding module provided by the embodiment of the present invention. Detailed Embodiments

[0124] The following combines the drawings and embodiments to further describe in detail the specific embodiments of the present invention. The following embodiments are used to illustrate the present invention, but are not used to limit the scope of the present invention.

[0125] The ship trajectory tracking system, as Figure 1 shown, includes a controlled ship, a state sensor, a state encoder of the ship trajectory tracking system, a transmitter, a management control system, a receiver, and an actuator that are connected in sequence.

[0126] ​This embodiment provides a state encoder for a ship trajectory tracking system and its encoding method, which is mainly applicable to the ship trajectory tracking system, and is particularly suitable for state encoding in the case of limited communication bandwidth of the ship trajectory tracking system, realizing effective information communication between the controlled ship and the management and control system, and ensuring the safety management and effective control of various ships in urban ports or sea lanes.

[0127] The state encoder of the ship trajectory tracking system in this embodiment, as Figure 2 shown, includes an information acquisition module, a state decoupling module, a primary encoding module, a secondary encoding module, a data encryption module, and a channel encoding module that are connected in sequence.

[0128] The information acquisition module is used to obtain the state of the ship trajectory tracking system from the state sensor. The information acquisition module sets the sampling time of the ship trajectory tracking system state to h seconds, and obtains the state value of the ship trajectory tracking system from the state sensor every h seconds. The state sampling value of the ship trajectory tracking system at the k-th moment is set as D(k) ∈ R n . Here it is assumed that: at the k-th moment, the ship trajectory tracking system has n states to be transmitted to the management and control system. Let d i (k) ∈ R represent the i-th state variable at the k-th moment, then there is:

[0129] D(k) = [d1(k) d2(k)…d n (k)] T

[0130] For the state sampling value D(k) of the ship trajectory tracking system at each moment, the information acquisition module stores it and sends it to the state decoupling module.

[0131] The state decoupling module, as Figure 3 shown, is used to obtain the state sampling value D(k) of the ship trajectory tracking system from the information acquisition module, and based on the dynamic characteristics of the ship trajectory tracking system, establish a system state equation and perform state decoupling.

[0132] The established system state equation is shown as follows:

[0133] D(k + 1) = AD(k) + BU(k) + FW(k)

[0134] where, U(k) ∈ R p is the control output of the management and control system; W(k) ∈ R q is the noise and interference generated in the ship trajectory tracking system; A, B, and F are multi-dimensional numerical matrices, and their values are determined by the ship type and control strategy.

[0135] To reduce the impact of communication bandwidth limitations and improve coding efficiency, state decoupling is required for the state equation of the ship trajectory tracking system. There exists a non-singular matrix H with real number values, and it is set that:

[0136]

[0137] where, m i ∈R, i = 1, 2, …, n.

[0138] Denote the decoupled system state as shown in the following equation:

[0139]

[0140] The state equation of the decoupled ship trajectory tracking system is transformed into:

[0141]

[0142] Set:

[0143] HBU(k) = [u1(k) u2(k) … u n (k)] T

[0144] HFW(k) = [w1(k) w2(k) … w n (k)] T

[0145] Let denote the i-th state variable of the decoupled ship trajectory tracking system state at time k, and for any we can obtain:

[0146]

[0147] Therefore, the state of the decoupled ship trajectory tracking system can be calculated Set:

[0148]

[0149] The state decoupling module sends the state equation of the decoupled ship trajectory tracking system and the decoupled system state to the primary coding module.

[0150] The primary coding module, as Figure 4 shown, is used to obtain the state equation of the decoupled ship trajectory tracking system and the decoupled system state from the state decoupling module and perform primary coding on to calculate the corresponding binary equal-length codewords c1(k), c2(k), …, c​n (k). The main task of the primary coding module is to convert the dynamic values of the ship trajectory tracking system that are not convenient for wireless channel transmission into binary numbers, perform data compression, reduce the required information transmission rate, and improve the coding efficiency. The specific coding method is as follows:

[0151] First, the primary coding module performs the update calculation of the state bound γ of the state variable of the decoupled ship trajectory tracking system at the k-th moment and the i-th i (k).

[0152] Let and γ i (k) represent the compressed state prediction value and the state bound of the state variable of the decoupled ship trajectory tracking system at the k-th moment and the i-th respectively, then there is:

[0153]

[0154] Among them, γ i (k) changes with time and needs to be recalculated before each coding. The calculation method is as follows:

[0155]

[0156] Among them, represents the upper bound of the value of w i (k); n i represents the compression parameter used when quantifying .

[0157] The primary coding module sets the compression parameter n of the state variable of the decoupled ship trajectory tracking system and calculates the compressed state prediction value i

[0158] The primary coding module sets the compression parameter n of the state variable of the decoupled ship trajectory tracking system, and the calculation method is as follows: i

[0159]

[0160] Among them, |·| represents the absolute value symbol, represents the ceiling function.

[0161] The primary coding module calculates the compressed state prediction value of the state variable of the decoupled ship trajectory tracking system , and the calculation method is as follows:

[0162]

[0163] Among them, represents the compressed state value of the i-th decoupled ship trajectory tracking system state variable at the (k - 1)th moment. of.

[0164] The primary coding module is based on the updated state bound γ i (k), the compression parameter n i and the predicted compressed state value to calculate the compressed state value of the decoupled ship trajectory tracking system state variable of.

[0165] Let represent the predicted compressed state error value of the decoupled ship trajectory tracking system state variable , and the calculation method is as follows:

[0166]

[0167] Divide the interval (-γ i (k), γ i (k)) into n i equal sub-intervals as follows:

[0168]

[0169] Observe the predicted compressed state error value of the decoupled ship trajectory tracking system state variable to determine which of the above n i sub-intervals it is in. Then, the midpoint value of the corresponding sub-interval is set as the compressed state value of the decoupled ship trajectory tracking system state variable of.

[0170] For example: When the predicted compressed state error value is in the first sub-interval above , then the midpoint value of this sub-interval is: Then there is:

[0171]

[0172] Thus, the compressed state value of the decoupled ship trajectory tracking system state variable is calculated as

[0173] The primary coding module encodes the compressed state value of the decoupled ship trajectory tracking system state variable Perform encoding to calculate the corresponding binary equal-length codeword c i (k).

[0174] Divide the interval (-γ i (k), γ i (k)) into n i equally divided sub-intervals and number them: The r-th sub-interval is numbered r. Let l i (k) represent the length of the binary equal-length codeword c i (k), and the calculation method is as follows:

[0175]

[0176] Observe the compressed state prediction error value of the decoupled ship trajectory tracking system state variable . If it is located in one of the n i sub-intervals, then convert the corresponding sub-interval number r into a binary number with a length of l i (k), and this binary number is the binary equal-length codeword c i (k). The primary encoding module sends the binary equal-length codeword c i (k) to the secondary encoding module.

[0177] The secondary encoding module is used to obtain the binary equal-length codeword c i (k) from the primary encoding module, then merge c1(k), c2(k), …, c n (k) into a binary sequence with a length of L(k), and perform secondary encoding on it using the LZ encoding method to generate the codeword C(k).

[0178] The calculation formula for the length L(k) is as follows:[[]]END]]

[0179]

[0180] The secondary encoding module sends the generated codeword C(k) to the data encryption module.

[0181] The data encryption module is used to obtain the generated codeword C(k) from the secondary encoding module, then perform data encryption on the codeword C(k) using the DES cryptographic algorithm to ensure data security, and generate a binary sequence G(k) with a length of L(k). The data encryption module sends the encrypted binary sequence G(k) to the channel encoding module.

[0182] The channel coding module is used to obtain the generated binary sequence G(k) after encryption from the data encryption module, and then perform channel coding on the binary sequence G(k) using the coding method of binary (N(k), L(k)) Hamming code. The main task of the channel coding module is to endow the coded codeword with the ability of error detection and correction, so as to reduce the influence of wireless channel noise and interference. The channel coding module sends the generated coded codeword to the transmitter.

[0183] A state coding method for a ship trajectory tracking system is implemented by using the above-mentioned ship trajectory tracking system state encoder, and includes the following steps:

[0184] Step 1: The information acquisition module obtains the state of the ship trajectory tracking system from the state sensor; the information acquisition module sets the sampling time of the ship trajectory tracking system state to h seconds, and obtains the state value of the ship trajectory tracking system from the state sensor every h seconds. The state sampling value of the ship trajectory tracking system at the k-th moment is set as D(k) ∈ R n ; Here it is assumed that: at the k-th moment, the ship trajectory tracking system has n states to be transmitted to the management and control system. Let d i (k) ∈ R represent the i-th state variable at the k-th moment, then there is:

[0185] D(k) = [d1(k) d2(k)…d n (k)] T

[0186] For the state sampling value D(k) of the ship trajectory tracking system at each moment, the information acquisition module stores it and sends it to the state decoupling module.

[0187] Step 2: The state decoupling module obtains the state sampling value D(k) of the ship trajectory tracking system from the information acquisition module. In order to improve the coding efficiency, it decouples it and provides the decoupled state value of the ship trajectory tracking system to the primary coding module for coding; the specific method is:

[0188] Step 2.1: Based on the dynamic characteristics of the ship trajectory tracking system, establish the system state equation as follows:

[0189] D(k + 1) = AD(k) + BU(k) + FW(k)

[0190] where, U(k) ∈ R p is the control output of the management and control system; W(k) ∈ R q is the noise and interference generated in the ship trajectory tracking system; A, B, F are multi-dimensional numerical matrices, and their values are determined by the ship type and control strategy;

[0191] Step 2.2: Calculate the transformation matrix;

[0192] To reduce the impact of communication bandwidth limitations and improve coding efficiency, state decoupling is required for the state equation of the ship trajectory tracking system. There exists a non-singular matrix H with real number values. The transformation matrix M is set as follows:

[0193]

[0194] where m i ∈R, i = 1, 2, …, n;

[0195] Step 2.3: Calculate the decoupled state equation;

[0196] Denote the decoupled system state as shown in the following equation:

[0197]

[0198] The state equation of the decoupled ship trajectory tracking system is transformed into:

[0199]

[0200] Step 2.4: Calculate the state of the decoupled ship trajectory tracking system;

[0201] Set:

[0202] HBU(k) = [u1(k) u2(k) … u n (k)] T

[0203] HFW(k) = [w1(k) w2(k) … w n (k)] T

[0204] For any It can be obtained that:

[0205]

[0206] Therefore, the state of the decoupled ship trajectory tracking system can be calculated as shown in the following equation:

[0207]

[0208] The state decoupling module sends the state equation of the decoupled ship trajectory tracking system and the decoupled system state to the primary coding module.

[0209] Step 3: The primary coding module obtains the state equation of the decoupled ship trajectory tracking system and the decoupled system state from the state decoupling module For Perform primary coding; the main task of the primary coding module is to convert the dynamic values of the ship trajectory tracking system that are not convenient for wireless channel transmission into binary numbers and perform data compression to reduce the required information transmission rate and improve the coding efficiency; the specific method is as follows:

[0210] Step 3.1: Update and calculate the state bound γ of the decoupled ship trajectory tracking system state i (k).

[0211] Let and γ i (k) represent the compressed state prediction value and the state bound of the i-th decoupled ship trajectory tracking system state variable at time k, respectively, then there is:

[0212]

[0213] Among them, γ i (k) changes with time and needs to be recalculated before each coding. The calculation method is as follows:

[0214]

[0215] Among them, represents the upper bound of the value of w i (k); n i represents the compression parameter used when quantifying ;

[0216] Step 3.2: Set the compression parameter n of the decoupled ship trajectory tracking system state variable i , and calculate the compressed state prediction value

[0217] The calculation method of the compression parameter n i is as follows:

[0218]

[0219] Calculate the compressed state prediction value of the decoupled ship trajectory tracking system state variable The calculation method is as follows:

[0220]

[0221] Among them, represents the compressed state value of the i-th decoupled ship trajectory tracking system state variable at time k-1;

[0222] Step 3.3: Based on the updated state bound γ i (k), compression parameter n i and compression state prediction value Calculate the state variables of the decoupled ship trajectory tracking system The compression status value

[0223] make Represents the state variables of the decoupled ship trajectory tracking system The compression state prediction error value is calculated as follows:

[0224]

[0225] The interval (-γ i (k), γ i (k)) is divided into n i The small intervals are as follows:

[0226]

[0227] Observe the state variables of the ship trajectory tracking system after decoupling The compression state prediction error value Located above i Which of the small intervals corresponds to the midpoint value of the small interval, which is set as the state variable of the decoupled ship trajectory tracking system The compression status value

[0228] For example: When the compression state prediction error value Located in the first small area above Then the midpoint value of this small interval is: Then we have:

[0229]

[0230] Thus, the state variables of the decoupled ship trajectory tracking system are calculated: The compression status value

[0231] Step 3.4: The primary encoding module calculates the state variables of the decoupled ship trajectory tracking system The compression status value Encode and calculate the corresponding binary equal-length codeword c i (k);

[0232] The interval (-γ i (k), γ i (k)) Average distribution of n iNumber the sub - intervals: The r - th sub - interval is numbered r. Let l i (k) represent the length of the binary equal - length codeword c i (k), and the calculation method is as follows:

[0233]

[0234] Observe the state variables of the decoupled ship trajectory tracking system of the compressed state prediction error value If it is located in one of the above n i sub - intervals, then convert the number r of the corresponding sub - interval into a binary number with length l i (k). This binary number is the binary equal - length codeword c i (k); The primary encoding module sends the binary equal - length codeword c i (k) to the secondary encoding module.

[0235] Step 4: After the secondary encoding module obtains the binary equal - length codeword c i (k) from the primary encoding module, it combines c1(k), c2(k), …, c n (k) into a binary sequence with length L(k), and performs secondary encoding on it using the LZ encoding method to generate the codeword C(k);

[0236] The formula for calculating the length L(k) is as follows:

[0237]

[0238] The secondary encoding module sends the generated codeword C(k) to the data encryption module.

[0239] Step 5: The data encryption module obtains the generated codeword C(k) from the secondary encoding module, and uses the DES cipher algorithm to encrypt the data to ensure data security, generating a binary sequence G(k) with length L(k). The data encryption module sends the encrypted binary sequence G(k) to the channel encoding module.

[0240] Step 6: The channel encoding module obtains the encrypted binary sequence G(k) from the data encryption module, and uses the encoding method of binary (N(k), L(k)) Hamming code to perform channel encoding on the binary sequence G(k). The main task of the channel encoding module is to make the encoded codeword have the ability of error detection and error correction, so as to reduce the influence of wireless channel noise and interference. The channel encoding module sends the encoded codeword to the transmitter.

[0241] The state encoder of the ship trajectory tracking system and its encoding method provided by this embodiment are mainly applicable to the ship trajectory tracking system, and are particularly suitable for state encoding when the communication bandwidth of the ship trajectory tracking system is limited. It can effectively reduce the influence of noise and interference in the wireless communication channel, improve the encoding efficiency, realize the effective information communication between the controlled ship and the management control system, and ensure the safe management and effective control of various ships in urban ports or sea lanes.

[0242] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope defined by the claims of the present invention.

Claims

1. A state encoder for a ship trajectory tracking system, characterized in that: It includes an information acquisition module, a state decoupling module, a primary encoding module, a secondary encoding module, a data encryption module, and a channel encoding module that are connected in sequence; The information acquisition module is used to obtain the state sampling value D(k) of the ship trajectory tracking system from the state sensor; the information acquisition module sets the sampling time of the ship trajectory tracking system state to h seconds, and obtains the state sampling value of the ship trajectory tracking system from the state sensor every h seconds; the state sampling value of the ship trajectory tracking system at the k-th moment is set as D(k) ∈ R n , D(k) = [d1(k) d2(k) … d n (k)] T ; where, d i (k) ∈ R represents the i-th state variable at the k-th moment; there are n state variables of the ship trajectory tracking system that need to be transmitted to the management and control system at the k-th moment; the information acquisition module stores the state sampling value D(k) of the ship trajectory tracking system at each moment and sends it to the state decoupling module; The state decoupling module is used to establish a system state equation based on the dynamic characteristics of the ship trajectory tracking system, perform state decoupling, and send the decoupled ship trajectory tracking system state equation and the decoupled ship trajectory tracking system state to the primary coding module; the specific method for the state decoupling module to perform decoupling is as follows: Based on the dynamic characteristics of the ship trajectory tracking system, a system state equation is established as follows: D(k + 1) = AD(k) + BU(k) + FW(k) where U(k) ∈ R p is the control output of the management control system; W(k) ∈ R q is the noise and interference generated in the ship trajectory tracking system; A, B, and F are multi-dimensional numerical matrices, and their values are determined by the ship type and control strategy; There exists a non-singular matrix H with real number values. The transformation matrix M is set as: where m i ∈R, i = 1, 2, …, n; Indicates the decoupled system state value, as shown in the following equation: The state equation of the decoupled ship trajectory tracking system is transformed into: Set: HBU(k) = [u1(k) u2(k) … u n (k)] T HFW(k) = [w1(k) w2(k) … w n (k)] T Let represent the i-th state variable of the decoupled ship trajectory tracking system at time k , then we have: The state of the decoupled ship trajectory tracking system is shown as follows: The state decoupling module sends the decoupled state equation of the ship trajectory tracking system and the state of the ship trajectory tracking system to the primary coding module; The primary coding module is used to perform primary coding on the n state variables of the decoupled ship trajectory tracking system state to calculate the corresponding binary equal-length codewords c1(k), c2(k), …, c n (k), and send the binary equal-length codewords c1(k), c2(k), …, c n (k) to the secondary coding module; the specific method is as follows: Update and calculate the state bound γ(k) of the state variables of the i-th decoupled ship trajectory tracking system at time k. of the state bound γ i (k). Let and γ i (k) represent the compressed state prediction value and state bound of the state variable of the i-th decoupled ship trajectory tracking system at time k, respectively , then there is Among them, γ i (k) changes with time and needs to be recalculated before each encoding. The calculation method is as follows: Among them, represents the upper bound of the value of w i (k); n i represents the compression parameter used when quantifying ​ Set the state variables of the decoupled ship trajectory tracking system The compression parameter n i , and calculate the predicted value of the compressed state The calculation method of the compression parameter n i is as follows: where |·| represents the absolute value symbol, represents the ceiling function; Calculating the state variables of the ship trajectory tracking system after decoupling The predicted value of the compressed state The calculation method is as follows: Among them, represents the compressed state value of the \(i\)-th decoupled ship trajectory tracking system state variable at the \((k - 1)\)-th moment ; Based on the updated calculated state bound γ i (k), compression parameter n i and the predicted value of the compressed state Calculate the decoupled state variables of the ship trajectory tracking system of the compressed state value Let represent the decoupled state variables of the ship trajectory tracking system of the predicted error value of the compressed state, and its calculation method is as follows: Divide the interval (-γ i (k), γ i (k)) into n i equal subintervals as follows: Observed state variables of the ship trajectory tracking system after decoupling Compressed state prediction error value Located in which of the above n i sub-intervals, then the midpoint value of the corresponding sub-interval is set as the state variable of the ship trajectory tracking system after decoupling Compressed state value The state variables of the decoupled ship trajectory tracking system of the compressed state value are encoded to calculate the corresponding binary equal-length codeword c i (k); the interval (-γ i (k), γ i (k)) is evenly divided into n i subintervals and numbered: the r-th subinterval is numbered r; let l i (k) represent the length of the binary equal-length codeword c i (k), and the calculation method is as follows: State variables of the ship trajectory tracking system after observation decoupling Compressed state prediction error value Located in n i Which small interval among the small intervals, then convert the number r of the corresponding small interval into a binary number with a length of l i (k), and this binary number is the binary equal-length codeword c i (k); The primary encoding module sends the binary equal-length codeword c i (k) to the secondary encoding module; The secondary encoding module is used to combine c1(k), c2(k), …, c n (k) into a binary sequence with a length of L(k), and perform secondary encoding on it using the LZ encoding method to generate a codeword C(k), and send the generated codeword C(k) to the data encryption module; the calculation formula for the length L(k) is as follows: The secondary encoding module sends the generated codeword C(k) to the data encryption module; The data encryption module is used to encrypt the codeword C(k) using the DES cryptographic algorithm to generate a binary sequence G(k) of length L(k), and send G(k) to the channel encoding module; The channel encoding module is used to perform channel encoding on the binary sequence G(k) using the encoding method of binary (N(k), L(k)) Hamming code, and send the generated codeword after encoding to the transmitter.

2. A method for encoding the state of a ship trajectory tracking system, implemented by using the ship trajectory tracking system state encoder described in claim 1, characterized in that: It includes the following steps: Step 1: The information acquisition module obtains the state sampling value D(k) of the ship trajectory tracking system from the state sensor; the information acquisition module sets the sampling time of the ship trajectory tracking system state to h seconds, and obtains the ship trajectory tracking system state value from the state sensor every h seconds; the ship trajectory tracking system state sampling value at the k-th moment is set as D(k) ∈ R n ; D(k) = [d1(k) d2(k) … d n (k)] T ; where, d i (k) ∈ R represents the i-th state variable at the k-th moment; there are n state variables of the ship trajectory tracking system to be transmitted to the management control system at the k-th moment; The state sampling value D(k) of the ship trajectory tracking system at each moment is stored and sent to the state decoupling module; Step 2: The state decoupling module decouples the sampled value D(k) of the ship trajectory tracking system state and provides the decoupled ship trajectory tracking system state to the primary encoding module for encoding. The specific method is as follows: to be provided to the primary encoding module for encoding; the specific method is: Step 2.1: Based on the dynamic characteristics of the ship trajectory tracking system, a system state equation is established as follows: D(k + 1) = AD(k) + BU(k) + FW(k) where U(k) ∈ R p is the control output of the management control system; W(k) ∈ R q is the noise and interference generated in the ship trajectory tracking system; A, B, and F are multi-dimensional numerical matrices, the values of which are determined by the ship type and control strategy; Step 2.2: Calculate the transformation matrix; There exists a non-singular matrix H with real number values. The transformation matrix M is set as: where m i ∈R, i = 1, 2, …, n; Step 2.3: Calculate the decoupled state equation; Indicates the decoupled system state, as shown in the following equation: The state equation of the decoupled ship trajectory tracking system is transformed into: Step 2.4: Calculate the state of the decoupled ship trajectory tracking system; Set: HBU(k) = [u1(k) u2(k) … u n (k)] T HFW(k) = [w1(k) w2(k) … w n (k)] T For the state of the decoupled ship trajectory tracking system at any moment k the i-th state variable Then we get: Then the state of the decoupled ship trajectory tracking system is shown as follows: Step 3: The primary coding module performs primary coding on the n state components of, and calculates the corresponding binary equal-length codewords c1(k), c2(k), …, c n (k), and sends the binary equal-length codewords c1(k), c2(k), …, c n (k) to the secondary coding module; the specific method is as follows: Step 3.1: Update and calculate the state bound γ of the state variable of the i-th decoupled ship trajectory tracking system at time k i (k): Let and γ i (k) represent the compressed state prediction value and state bound of the state variable of the i-th decoupled ship trajectory tracking system at time k, respectively Then there is: Among them, γ i (k) changes with time and needs to be recalculated before each encoding. The calculation method is as follows: Among them, represents the upper bound of the value of w i (k); n i represents the compression parameter used when quantifying ​ Step 3.2: Set the state variables of the decoupled ship trajectory tracking system compression parameter n of i and calculate the predicted value of the compressed state Compression parameter n i is calculated as follows: where |·| represents the absolute value symbol, represents the ceiling function; Calculating the state variables of the ship trajectory tracking system after decoupling The predicted value of the compressed state The calculation method is as follows: Among them, represents the compressed state value of the i-th decoupled ship trajectory tracking system state variable at the (k - 1)th moment ; Step 3.3: Based on the updated and calculated state bound γ i (k), compression parameter n i and the predicted value of the compression state Calculate the decoupled state variables of the ship trajectory tracking system of the compression state value Let represent the compressed state prediction error value of the decoupled ship trajectory tracking system state variable , and the calculation method is as follows: Divide the interval (-γ i (k), γ i (k)) into n i equal subintervals as follows: Observed state variables of the ship trajectory tracking system after decoupling Compressed state prediction error value Located in which of the above n i sub-intervals, then the midpoint value of the corresponding sub-interval is set as the state variable of the ship trajectory tracking system after decoupling Compressed state value Step 3.4: For the decoupled state variables of the ship trajectory tracking system compressed state values perform encoding to calculate the corresponding binary equal-length codeword c i (k); Divide the interval (-γ i (k), γ i (k)) into n i equally divided subintervals and number them: the r-th subinterval is numbered r; Let l i (k) denote the length of the binary equal-length codeword c i (k), and the calculation method is as follows: State variables of the ship trajectory tracking system after observation decoupling Compressed state prediction error value Located in n in step 3.3 i Which small interval among the small intervals, then convert the number r of the corresponding small interval into a binary number with a length of l i (k), and this binary number is the binary equal-length codeword c i (k); Step 4: The secondary encoding module combines c1(k), c2(k), …, c n (k) into a binary sequence of length L(k), and performs secondary encoding on it using the LZ encoding method to generate a codeword C(k), and sends the generated codeword C(k) to the data encryption module; the calculation formula for the length L(k) is as follows: Step 5: The data encryption module obtains the generated codeword C(k) from the secondary encoding module, encrypts it using the DES cryptographic algorithm to generate a binary sequence G(k) of length L(k), and sends G(k) to the channel encoding module; Step 6: The channel encoding module performs channel encoding on the binary sequence G(k) using the encoding method of binary (N(k), L(k)) Hamming code, and sends the generated codeword after encoding to the transmitter.

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