Unmanned aerial vehicle control method and device based on random key stream, and medium

Abstract

The invention discloses an unmanned aerial vehicle control method and device based on a random key stream, and a medium, and relates to the technical field of aircraft control. The method comprises the following steps: presetting a chaos initial value for a main chaos system of an encryption end; selecting a switching strategy according to the current state component of the main chaotic system so as to switch the auxiliary chaotic system; generating a random key stream coefficient through a seed random number generator, and combining the random key stream coefficient with the chaotic initial value to obtain a private key; acquiring an aircraft measurement data plaintext, injecting the plaintext into the chaotic system, and generating a ciphertext in combination with the random key stream coefficient; transmitting the ciphertext to a decryption end, synchronizing the private key and the switching strategy at the decryption end, and restoring the plaintext; the restored plaintext is input into a state feedback controller, an anti-saturation control instruction is generated, and the state feedback controller comprises a nonlinear compensation function. According to the method, the measurement data of the aircraft is encrypted and decrypted by the chaotic system key stream, the length of the private key is expanded, and the security is improved.

Description

Technical Field

[0001] This application relates to the technical field of aircraft control, and particularly to a method, device and medium for controlling an unmanned aerial vehicle based on a random key stream. Background Art

[0002] As a new type of aircraft that combines the high-speed cruise of a fixed wing and the flexible take-off and landing of a rotor, the complexity and industry challenges of a vertical take-off and landing fixed-wing aircraft (VTOL-FW) are mainly reflected in the contradiction among safety, real-time performance, and dynamic environment adaptability.

[0003] Currently, the technological development in this field is facing dual pressures: on the one hand, the rapid penetration of military and civilian scenarios requires the aircraft to maintain reliable control in complex electromagnetic environments and high-dynamic airspaces; on the other hand, the existing security architecture is difficult to meet the real-time encryption requirements of the aircraft during the mode switching stage, resulting in a significant expansion of the attack surface. Successful cases of malicious attacks are concentrated in the take-off and landing stages, and the attacks are achieved by reverse engineering to crack unencrypted measurement data, highlighting the fatal flaw of traditional communication protocols relying only on basic verification mechanisms.

[0004] Furthermore, due to the limitations of existing encryption technologies, although general algorithms such as AES-256 (Advanced Encryption Standard - 256-bit Key) perform excellently in data confidentiality, their millisecond-level computational delay cannot meet the stringent requirements for the real-time measurement feedback during the transition flight stage. Especially in critical actions such as tilt-rotor or thrust vector adjustment, the encryption delay may lead to attitude instability or even crash. More seriously, the communication frequency hopping and topology restructuring caused by the aircraft during multimodal flight make the traditional static key distribution mechanism frequently fail. Although most commercial flight control systems adopt full-link encryption, due to the lack of differential protection, the risk of system collapse is very high when facing selective replay attacks. This "security redundancy trap" stems from the fact that existing solutions do not incorporate dynamic flight state parameters into the encryption matrix, resulting in the disconnection between key updates and flight stages.

[0005] The V-247 UAV compresses the AES-256 processing time to 60 ms through a hardware acceleration module, but still cannot meet the requirements of the transition stage; Airbus's quantum key distribution technology has the advantage of anti-cracking in theory, but is limited by the deployment cost of quantum repeaters and is only applicable to fixed-route scenarios. In domestic research, the lightweight national cryptographic algorithm of the Institute of Automation, Chinese Academy of Sciences, reduces the encryption delay to 35 ms, but the lack of a key dynamic update mechanism leads to a sharp increase in the bit error rate in frequency hopping scenarios; DJI's instruction signature verification technology can resist replay attacks, but the time-consuming signature generation causes control loop hysteresis. These cases show that simply optimizing algorithms or hardware cannot systematically solve the balance problem between security and real-time performance.

[0006] Furthermore, the direction of technological breakthrough is evolving from a single encryption layer to cross-domain collaboration. The popularization of distributed electric propulsion technology, such as NASA's GL-10 Lightning UAV, has given rise to the need for an "energy-communication-control" integrated security architecture, promoting the deep coupling of encryption mechanisms and power systems. For example, Boeing's "Phantom Swift" generates dynamic key seeds through the tilting characteristics of the wingtip duct power device, binds the aircraft's motion state to the encryption timing, and initially achieves an encryption efficiency of 15 ms level. At the same time, the adaptive key distribution technology relies on the link quality prediction model, and the key synchronization success rate is improved in frequency hopping scenarios, significantly better than the benchmark value of traditional solutions. In the future, the integration of chaotic encryption and artificial intelligence may become the key - by using neural networks to real-time analyze low-altitude airflow data and optimize encryption matrix parameters, the instruction integrity verification and operation legality judgment can be synchronously completed in millisecond-level responses, thus constructing a three-in-one security protection system of "spatiotemporal correlation-dynamic evolution-autonomous repair".

[0007] Furthermore, during the complex and highly dynamic mode transition phase of VTOL-FW, such as from hover to forward flight or vice versa, the timeliness, integrity, and authenticity of measurement information are the lifeline for the Flight Control System (FCS) to maintain stability. At this time, the aircraft is in a state where its aerodynamic characteristics change drastically and control efficiency is uneven, such as changes in tilt-rotor angles and adjustments in thrust vector directions. The FCS's reliance on core measurement data such as attitude angles, angular rates, accelerations, positions, and velocities reaches its peak. Once an attacker tampers with, replays, or forges this measurement information updated in milliseconds, for example, injecting false attitude angle data, the FCS will generate catastrophic control instructions based on the incorrect state perception. At this point, the actuators will be forced to respond to these incorrect instructions and be instantly driven to their physical limits, i.e., actuator saturation. The saturated actuators not only lose their ability to further adjust the flight attitude, but the unexpected and high-amplitude error driving torques they generate will directly lead to the aircraft losing control, becoming unstable, or even suffering structural damage. Therefore, ensuring the security of measurement information throughout the transmission and processing link is the first and most important technical barrier to prevent malicious attacks from inducing actuator saturation and further causing catastrophic consequences.

[0008] Through the above analysis, the problems and deficiencies of the prior art are as follows: The encryption algorithms for aircraft in the prior art cannot meet the real-time encryption requirements of measurement data during the transitional flight phase due to delays, and the encryption delays of measurement data lead to actuator saturation and loss of control, further causing disasters. Summary of the Invention

[0009] The embodiments of the present application provide a method, device, and medium for controlling an unmanned aerial vehicle based on a random key stream, which can solve the problem that the encryption algorithms for aircraft in the prior art cannot meet the real-time encryption requirements of measurement data during the transitional flight phase due to delays, and the encryption delays of measurement data lead to actuator saturation and loss of control, further causing disasters.

[0010] In a first aspect, the embodiments of the present application provide a method for controlling an unmanned aerial vehicle based on a random key stream. The method includes: presetting a chaotic initial value for the main chaotic system at the encryption end based on a chaotic system including a main chaotic system and an auxiliary chaotic system; selecting a switching strategy according to the current state components of the main chaotic system to switch the auxiliary chaotic system; generating a random key stream coefficient through a seed random number generator, and combining the random key stream coefficient with the chaotic initial value to obtain a private key; obtaining the plaintext of the aircraft measurement data, injecting the plaintext into the chaotic system, and generating a ciphertext in combination with the random key stream coefficient; transmitting the ciphertext to the decryption end, synchronizing the private key and the switching strategy at the decryption end, and restoring the plaintext; inputting the restored plaintext into a state feedback controller to generate an anti-saturation control instruction, where the state feedback controller includes a nonlinear compensation function.

[0011] In an implementation manner of the present application, a switching strategy is selected according to the current state component of the main chaotic system to switch the auxiliary chaotic system, which specifically includes: The auxiliary chaotic system includes a first auxiliary system and a second auxiliary system; the state component of the main chaotic system is calculated in real time according to the initial value. When the state component is less than a preset value, the first auxiliary system is activated; when the state component is greater than the preset value, the second auxiliary system is activated.

[0012] In an implementation manner of the present application, a random key stream coefficient is generated by a seed random number generator, and the random key stream coefficient is combined with the chaotic initial value to obtain a private key, which specifically includes: A digital sequence with a preset length is used as a seed, and the seed is input into the random number generator to generate a random key stream coefficient; the seed is used as the prefix of the private key and combined with the chaotic initial value to obtain the private key.

[0013] In an implementation manner of the present application, the ciphertext is transmitted to the decryption end, and the private key and the switching strategy are synchronized at the decryption end to restore the plaintext, which specifically includes: The seed is distributed to the decryption end through a secure channel; the same random number generation algorithm is synchronously run at the encryption end and the decryption end; according to the chaotic initial value in the private key, the main chaotic system is synchronously run, and the auxiliary chaotic system is determined.

[0014] In an implementation manner of the present application, the restored plaintext is input into the state feedback controller to generate an anti-saturation control instruction, which specifically includes: Establishing a linear state space model of a vertical takeoff and landing fixed-wing aircraft at a preset operating point, and the linear state space model includes output saturation constraints; using the hyperbolic tangent function to approximate the saturation constraints; collecting the aircraft state vector, and the state vector includes components such as position, velocity, attitude angle, and angular velocity; designing a state feedback control law so that the output value of the state feedback controller is the inverse hyperbolic tangent function of the product of the state vector and a preset gain matrix, and the gain matrix is used to make all eigenvalues of the state vector have negative real parts.

[0015] In an implementation manner of the present application, a state feedback control law is designed, and the output value is the inverse hyperbolic tangent function of the state vector and a preset gain matrix, which specifically includes: Calculating the product of the state vector and the feedback gain parameter to generate an intermediate control vector; applying the inverse hyperbolic tangent function to each component of the intermediate control vector to obtain an operation result; outputting the operation result to the actuator to drive the rudder surface and the motor.

[0016] In an implementation manner of the present application, after using the hyperbolic tangent function to approximate the saturation constraints, the method further includes: Calculating the approximation error between the output value of the hyperbolic tangent function and the saturation constraint, and estimating the upper bound of the approximation error; injecting the upper bound into the state feedback control law to obtain a compensation gain, and adaptively adjusting the compensation gain.

[0017] In one implementation of the present application, the method further includes: when the number of consecutive decryption failures exceeds the threshold number, freezing the current control instruction; switching to a preset gain matrix, and calculating a conservative control instruction according to the preset gain matrix.

[0018] In a second aspect, an embodiment of the present application further provides a drone control device based on a random key stream. The device includes at least one processor; and a memory communicatively connected to the at least one processor; wherein, the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to: based on a chaotic system including a main chaotic system and an auxiliary chaotic system, preset a chaotic initial value for the main chaotic system at the encryption end; select a switching strategy according to the current state components of the main chaotic system to switch the auxiliary chaotic system; generate a random key stream coefficient through a seed random number generator, combine the random key stream coefficient with the chaotic initial value to obtain a private key; obtain the plaintext of the aircraft measurement data, inject the plaintext into the chaotic system, and generate a ciphertext in combination with the random key stream coefficient; transmit the ciphertext to the decryption end, synchronize the private key and the switching strategy at the decryption end, and restore the plaintext; input the restored plaintext into a state feedback controller to generate an anti-saturation control instruction, and the state feedback controller includes a nonlinear compensation function.

[0019] In a third aspect, an embodiment of the present application further provides a non-volatile computer storage medium for drone control based on a random key stream, storing computer-executable instructions, and the computer-executable instructions are set to: based on a chaotic system including a main chaotic system and an auxiliary chaotic system, preset a chaotic initial value for the main chaotic system at the encryption end; select a switching strategy according to the current state components of the main chaotic system to switch the auxiliary chaotic system; generate a random key stream coefficient through a seed random number generator, combine the random key stream coefficient with the chaotic initial value to obtain a private key; obtain the plaintext of the aircraft measurement data, inject the plaintext into the chaotic system, and generate a ciphertext in combination with the random key stream coefficient; transmit the ciphertext to the decryption end, synchronize the private key and the switching strategy at the decryption end, and restore the plaintext; input the restored plaintext into a state feedback controller to generate an anti-saturation control instruction, and the state feedback controller includes a nonlinear compensation function.

[0020] A method, device, and medium for controlling an unmanned aerial vehicle (UAV) based on a random key stream provided by an embodiment of the present application switch a chaotic system in an encryption algorithm and randomly distribute key stream coefficients, so that the key stream of the chaotic system is amplified or reduced, and then the new key stream is used to encrypt and decrypt the measurement data of the aircraft. By extending the length of the private key, the security is improved; in addition, the key stream coefficients generated by the seed random number generator also improve the security of encryption and decryption; on the basis of ensuring the security of the measurement data, the hyperbolic tangent function and the state feedback control law are used to transform the physical constraints of the actuator into a smooth function, eliminate the chattering phenomenon caused by traditional hard saturation, and design a UAV control algorithm resistant to actuator saturation, which improves the application of the UAV in actual scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments and descriptions thereof of the present application are used to explain the present application and do not constitute an improper limitation of the present application. In the drawings: Figure 1 is a flowchart of a method for controlling a UAV based on a random key stream provided by an embodiment of the present application; Figure 2 is a schematic diagram of the overall process architecture of a method for controlling a UAV based on a random key stream provided by an embodiment of the present application; Figure 3 is a schematic diagram of the encryption end process of a method for controlling a UAV based on a random key stream provided by an embodiment of the present application; Figure 4 is a schematic diagram of the decryption end process of a method for controlling a UAV based on a random key stream provided by an embodiment of the present application; Figure 5 is a schematic diagram of the extension and distribution of the random key stream of a method for controlling a UAV based on a random key stream provided by an embodiment of the present application; Figure 6 is a schematic diagram of the internal structure of a device for controlling a UAV based on a random key stream provided by an embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] To make the objectives, technical solutions, and advantages of the present application clearer, the technical solutions of the present application will be clearly and completely described below in conjunction with the specific embodiments of the present application and the corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application.

[0023] The embodiments of the present application provide a method, device, and medium for controlling an unmanned aerial vehicle based on a random key stream, which solve the problem that the encryption algorithm of the existing technology cannot meet the real-time encryption requirements of measurement data during the transition flight stage due to delay, and the encryption delay of the measurement data causes the actuator to saturate and get out of control, further leading to disasters.

[0024] The technical solutions proposed in the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0025] Figure 1 It is a flowchart of a method for controlling an unmanned aerial vehicle based on a random key stream provided by the embodiments of the present application. As Figure 1 shown, a method for controlling an unmanned aerial vehicle based on a random key stream provided by the embodiments of the present application specifically includes the following steps: Step 10: Based on the chaotic system including the main chaotic system and the auxiliary chaotic system, preset the chaotic initial value for the main chaotic system at the encryption end.

[0026] The embodiments of the present application consist of a chaotic encryption part based on the key stream coefficient and an aircraft control part, specifically a saturation control algorithm for a vertical takeoff and landing fixed-wing aircraft based on an extended key and a switched chaotic system encryption. The specific algorithm architecture diagram is as Figure 2 shown. The following will introduce the two parts separately.

[0027] First, it can be understood that the Lorenz nonlinear system is a typical chaotic system, and its dynamic equations are composed of three nonlinear differential equations, and the parameters include σ (Prandtl number), ρ (Rayleigh number), and β. This system is famous for the "butterfly effect" and exhibits typical chaotic characteristics of exponential divergence of trajectories caused by small differences in initial conditions. Its attractor has a double-scroll structure, and its state equation is:

[0028] Among them, , , is the state of the system, is the output of the system. When , ,

[0029] ​​​The Chen chaotic system is regarded as an extension of the Lorenz system. Its equation form is similar to that of the Lorenz system, but by adjusting the parameters and coupling terms, the Chen system exhibits more complex dynamic behaviors. For example, the attractor structure has both folding and rotation characteristics, and there are more abundant chaotic and periodic state switches within the parameter range. Due to its high parameter sensitivity, this system is widely used in research on secure communication and chaotic synchronization control. The state-space expression of the Chen nonlinear system is given as follows:

[0030] where, , , are the states of the system, is the output of the system. When , , , the Chen system exhibits chaotic phenomena.

[0031] In this step, for the Lorenz chaotic system and the Chen chaotic system, the embodiments of the present application first consider injecting the plaintext to be encrypted into the output equations of the two systems respectively, and then multiplying the key streams by a coefficient and , respectively, that is: Lorenz plaintext injection system :

[0032] Chen plaintext injection system :

[0033] Then, the two plaintext injection systems and are combined to form a generalized switched chaotic system, that is:

[0034] where, is the switching signal, indicating that at time , the chaotic system or is activated.

[0035] The switching strategy of the switching signal is as follows: In the encryption module, the embodiments of the present application consider using the Lorenz chaotic system as the basic decision model. Under the condition of setting the initial value of the chaotic system, the encryption end judges the state of the Lorenz chaotic system. If , then ; If , then . The mathematical expression is as follows:

[0036] The chaos encryption algorithm based on the switched chaotic system is as Figure 3 shown. Note that this encryption scheme can be extended to multiple chaotic systems for switching. Specifically, consider the Lorenz chaotic system, the Chen chaotic system, and the Rossler chaotic system. The Rossler system is a chaotic model with relatively simple structure, containing only one non - linear term. Under the adjustment of its parameters, it can exhibit the mixed characteristics of spiral attractors and folded trajectories. Typical behaviors include single - scroll chaos and periodic oscillations. The Rossler system is often used for the analysis of the basic mechanism of chaos due to its low - dimensional characteristics and is used as a benchmark model for theoretical research in interdisciplinary fields such as chemical oscillations and biological rhythms. The state equations of the Rossler chaotic system are as follows:

[0037] where, , , are the states of the system, is the output of the system. When , , , , the Rossler system exhibits chaotic phenomena.

[0038] Step 20: Select a switching strategy according to the current state components of the main chaotic system to switch the auxiliary chaotic system.

[0039] As an alternative embodiment, select a switching strategy according to the current state components of the main chaotic system to switch the auxiliary chaotic system, which may specifically include: The auxiliary chaotic system includes a first auxiliary system and a second auxiliary system; Step 201: Calculate the state components of the main chaotic system in real - time according to the initial value. When the state components are less than the preset value, activate the first auxiliary system; Step 202: When the state components are greater than the preset value, activate the second auxiliary system.

[0040] In this step, the Lorenz chaotic system is still used as the basic model, but the switching strategy of the switching signal needs to be updated as follows: When the state of the Lorenz chaotic system , then ; When the state of the Lorenz chaotic system , then ; When the state of the Lorenz chaotic system , then . The mathematical expression is as follows:

[0041] As Figure 3 shown, note that the key stream coefficients are further introduced , and . The generation of the key stream coefficients can cooperate with the initial value of the Lorenz system state as the private key for chaotic encryption and decryption, which will increase the length of the private key; at the same time, the key stream coefficients can be real numbers, so the encryption and decryption scheme greatly improves the security.

[0042] The following will explain the key stream coefficients.

[0043] Step 30: Generate random key stream coefficients through a seed random number generator, and combine the random key stream coefficients with the chaotic initial value to obtain the private key.

[0044] As an alternative embodiment, generating random key stream coefficients through a seed random number generator and combining the random key stream coefficients with the chaotic initial value to obtain the private key may specifically include: Step 301: Use a digital sequence of a preset length as the seed, input the seed into the random number generator to generate random key stream coefficients; Step 302: Use the seed as the prefix of the private key and combine it with the chaotic initial value to obtain the private key.

[0045] In this step, in order to improve the system security, the embodiment of the present application adopts an extended key scheme for random key stream coefficients, which is specifically described as follows: Use 9 digits in the integer as the seed and also as the first two digits of the private key; the encryption unit and the decryption unit share this seed; then use the random number generator, according to the seed , the encryption unit and the decryption unit simultaneously generate the same random number , and these two random numbers are used as the key stream coefficients to prepare for subsequent plaintext encryption and decryption.

[0046] The chaotic encryption system utilizes the high sensitivity and unpredictability of the chaotic sequence to achieve good encryption performance, and is particularly suitable for communication scenarios that are sensitive to initial values and require high complexity. However, the system security depends to a large extent on the key: the confidentiality and synchronization of the initial conditions and system parameters. Therefore, key distribution becomes an essential part of the security architecture of the chaotic encryption system. If the key distribution process is not secure, even if the encryption algorithm itself has strong chaos, the system may easily fail due to key leakage. A secure and reliable key distribution mechanism not only ensures the synchronous generation of chaotic sequences by both communication parties, but also prevents man-in-the-middle attacks and replay attacks, which is a basic prerequisite for the practical application of the chaotic encryption system.

[0047] The chaotic sequence generated by a chaotic system is extremely sensitive to the system's initial value. A slight perturbation of the initial value can drastically change the chaotic sequence generated by the chaotic system. Therefore, the initial value of the chaotic system is usually used as the key for chaotic encryption. Since this scheme uses a switching chaotic system as the key stream generator, the key is selected as:

[0048] Therefore, the private key structure is ,like Figure 5 shown.

[0049] Step 40: Obtain the plaintext of the aircraft measurement data, inject the plaintext into the chaotic system, and generate ciphertext by combining it with the random key stream coefficient.

[0050] Step 50: Transmit the ciphertext to the decryption end, synchronize the private key and switching strategy at the decryption end, and restore the plaintext.

[0051] In this step, the presence of a decryption module is crucial in chaotic encryption communication systems. Because the encryption process introduces a chaotic sequence that performs complex nonlinear transformations on the original information, the receiving end must have an effective decryption mechanism to accurately reconstruct the original data based on the known key information. The high sensitivity of chaotic systems means that even small parameter errors can cause decryption failures. Therefore, the decryption module must not only achieve synchronous reproduction of the chaotic sequence but also ensure a certain degree of robustness against disturbances and noise. Without a decryption module, the encrypted information cannot be correctly recovered, rendering the entire communication process meaningless. Therefore, designing a high-precision, highly synchronized, and robust decryption module is fundamental to the reliable application of chaotic encryption systems.

[0052] As an optional embodiment, the ciphertext is transmitted to the decryption end, the private key and switching strategy are synchronized at the decryption end, and the plaintext is restored. Specifically, it may include: step 501: distributing the seed to the decryption end through a secure channel; step 502: synchronously running the same random number generation algorithm at the encryption end and the decryption end; step 503: synchronously running the main chaotic system according to the chaotic initial value in the private key, and determining the auxiliary chaotic system.

[0053] In this step, as mentioned in step 302, the encryption unit and the decryption unit share the seed; then a random number generator is used to generate the random number according to the seed. , the encryption unit and decryption unit generate the same random number at the same time The decryption end reproduces the same chaotic sequence based on the chaotic initial value.

[0054] Then, the key stream is subtracted from the ciphertext to obtain the measurement plaintext, such as Figure 4 As shown, the decryption equation is as follows:

[0055] Step 60: Input the restored plaintext into the state feedback controller to generate an anti-saturation control instruction. The state feedback controller includes a nonlinear compensation function.

[0056] First of all, it can be understood that the vertical takeoff and landing fixed-wing aircraft is an innovative aircraft that combines the vertical takeoff and landing capabilities of multi-rotors with the long endurance and high-speed flight characteristics of fixed wings. Its core design realizes vertical takeoff and landing through a multi-rotor or tilting power system, and then switches to the fixed-wing mode for efficient cruising.

[0057] Generally, the vertical takeoff and landing fixed-wing aircraft is characterized by 12 states in its dynamic and kinematic models, namely , which respectively represent position, velocity, attitude, and angular velocity. Due to the strong coupling between the states of the vertical takeoff and landing fixed-wing aircraft, the dynamic system of the vertical takeoff and landing fixed-wing aircraft has strong nonlinear characteristics. Affected by factors such as aerodynamic force changes, large attitude adjustments, and propulsion system coupling, directly designing a controller for the complete nonlinear model usually faces problems such as complex modeling, difficult analysis, and unsolvable control laws.

[0058] Therefore, in this step, in order to simplify the controller design, system linearization can be selected near a specific operating point related to the flight mission. Through operating point linearization, a local linear approximation model can be obtained, enabling the application of traditional linear control theories: pole placement, optimal control, robust control, etc., thereby greatly reducing the complexity of controller design and stability analysis, and at the same time facilitating efficient engineering deployment and performance verification. Therefore, the linear system obtained after operating point linearization is described as follows:

[0059] where , ,

[0060]

[0061] x(t) is the state vector of the system, including position, velocity, attitude angle, angular velocity, etc., which is a set of variables describing the current state of the aircraft; A is the system matrix, reflecting the inertial and aerodynamic coupling of the aircraft's own dynamic characteristics, and determining the natural change law of the state over time; B is the input matrix, describing the influence degree of the control input on the state, such as how the rudder surface deflection changes the aircraft's attitude; u(t) is the control input vector, such as motor thrust, rudder surface deflection angle, etc., generated by the controller. This equation describes how the aircraft state changes over time - the current state x and the control input u jointly determine the state at the next moment.

[0062] The output equation of the system is ;

[0063] The encryption function defined in the embodiment of the present application can be ,Right now , the decryption function is ,Right now

[0064] As an optional embodiment, the restored plain text is input into a state feedback controller to generate anti-saturation control instructions, which may specifically include: Step 601: establishing a linear state space model of the vertical take-off and landing fixed-wing aircraft at a preset working point, the linear state space model including an output saturation constraint.

[0065] In this step, it is assumed that the decryption error is 0, and considering that the actuator of the vertical take-off and landing fixed-wing aircraft needs to be limited, it is necessary to study the actuator saturation problem. In this problem, the linearization equation of the vertical take-off and landing fixed-wing aircraft is changed to:

[0066] The saturation function is expressed as follows:

[0067] in, It is the upper bound of the saturated input. The embodiment of the present application uses the hyperbolic tangent function to limit the amplitude of the state control input, that is, it does contain the constraints of the upper and lower limits of the physical output capacity of the actuator.

[0068] Step 602: using a hyperbolic tangent function to approximate the saturation constraint; In this step, the mathematical properties of the hyperbolic tangent function are used to construct a smooth and continuous function to simulate and approximate the physical output limit of the actuator. A smooth function is defined as:

[0069] Then, the saturation function can be expressed as:

[0070] Approximation error Is a bounded unknown function, assuming the upper bound is ,but , the linearized equation of the vertical take-off and landing fixed-wing aircraft is transformed into:

[0071] Step 603: Collect the state vector of the aircraft, where the state vector includes components of position, velocity, attitude angle, and angular velocity; Step 604: Design a state feedback control law such that the output value of the state feedback controller is the inverse hyperbolic tangent function of the product of the state vector and a preset gain matrix, and the gain matrix is used to make all the eigenvalues of the state vector have negative real parts.

[0072] In this step, the finally output control command value is equal to the result vector obtained by multiplying the current state vector of the aircraft by the preset gain matrix, and then the inverse hyperbolic tangent function mathematical operation is performed on each element of this result vector respectively, and then the specific parameter values of the gain matrix are adjusted and determined such that the control system formed by applying this control law has stable characteristics in its internal dynamics.

[0073] As an optional embodiment, when designing the state feedback control law with the output value being the inverse hyperbolic tangent function of the state vector and the preset gain matrix, it may specifically include: Step 6041: Calculate the product of the state vector and the feedback gain parameter to generate an intermediate control vector; Step 6042: Apply the inverse hyperbolic tangent function to each component of the intermediate control vector to obtain an operation result; Step 6043: Output the operation result to the actuator to drive the control surface and the motor.

[0074] This application embodiment assumes a simple state feedback control scheme, that is:

[0075] where is the control gain parameter. In the control system, state feedback can directly utilize all or part of the state variables of the system and, by adjusting the input in real time, achieve precise adjustment of the dynamic performance of the system. Then the control law calculation is as follows:

[0076] where the symbol arh = arctanh.

[0077] Compared with the control method that only relies on output feedback, state feedback can significantly improve the stability, response speed, and robustness of the system. It can not only optimize the dynamic characteristics of the system through pole placement but also enhance the resistance to disturbances and model uncertainties. It is the basis for implementing high-performance control strategies such as optimal control, adaptive control, and robust control. The state equation of the closed-loop control system of the vertical takeoff and landing fixed-wing aircraft is as follows:

[0078] During the process of adjusting the control system parameters, as long as the control gain is selected such that The real part of the eigenvalue is less than 0, and it can be theoretically proved that the closed-loop system is input-to-state stable from the saturation function approximation error to the state, which can satisfy the boundedness of the state near the operating point of the system.

[0079] As an alternative embodiment, after approximating the saturation constraint using the hyperbolic tangent function, the method may further include: calculating the approximation error between the output value of the hyperbolic tangent function and the saturation constraint, and estimating the upper bound of the approximation error; injecting the upper bound into the state feedback control law to obtain a compensation gain, and adaptively adjusting the compensation gain.

[0080] In this step, the limitations of traditional static saturation compensation can actively suppress the impact of the hyperbolic tangent function approximation error on stability through an error observer and an adaptive injection mechanism, reducing the deviation between the actual output of the actuator and the theoretical command.

[0081] As an alternative embodiment, the method may further include: freezing the current control command when the number of consecutive decryption failures exceeds a threshold number; switching to a preset gain matrix, and calculating a conservative control command according to the preset gain matrix.

[0082] In this step, a cross-domain action between encryption failure and control security is established, and the control command is forced to be restricted within the linear working area of the actuator through a security gain matrix, avoiding instantaneous saturation out-of-control caused by malicious attacks or channel failures.

[0083] In summary, the present invention utilizes the characteristic that the chaotic nonlinear system is extremely sensitive to the initial value, and designs a saturation control algorithm for a vertical takeoff and landing fixed-wing aircraft encrypted based on the switching of the key stream coefficient of the chaotic system. This encryption algorithm relies on different chaotic systems, according to the designed switching strategy, uses the key streams generated by different chaotic systems, and the randomly generated key stream coefficients to encrypt the measurement data of the aircraft, so that the measurement data is transmitted in ciphertext form; when the decryption module receives the ciphertext measurement data, it uses the key to obtain the switching strategy of the key stream, and then calculates the original measurement data. In the key distribution module, a seed random number generator is used to distribute the key stream coefficients, increase the length of the private key, distribute the key, and enhance the security of plaintext encryption. The embodiments of the present application are applied to the encryption of the measurement data of a vertical takeoff and landing aircraft, so that the sensitive measurement data of the aircraft is protected.

[0084] In addition, this solution designs an anti-actuator saturation state feedback control algorithm based on the characteristics of the hyperbolic tangent function. This control algorithm combines the proposed chaotic encryption and decryption algorithm, making the flight of the aircraft safer and further applied to actual scenarios.

[0085] The above is the method embodiment proposed by the present application. Based on the same inventive concept, the embodiments of the present application also provide a UAV control device based on a random key stream, and its structure is as Figure 6 shown.

[0086] Figure 6 The figure is a schematic diagram of the internal structure of a drone control device based on a random key stream provided by an embodiment of the present application. As Figure 6 shown, the device includes: At least one processor 601; And a memory 602 communicatively connected to the at least one processor; Wherein, the memory 602 stores instructions executable by the at least one processor. The instructions are executed by the at least one processor 601 so that the at least one processor 601 can: Based on a chaotic system including a main chaotic system and an auxiliary chaotic system, preset a chaotic initial value for the main chaotic system at the encryption end; Select a switching strategy according to the current state components of the main chaotic system to switch the auxiliary chaotic system; Generate a random key stream coefficient through a seed random number generator, combine the random key stream coefficient with the chaotic initial value to obtain a private key; Obtain the plaintext of the aircraft measurement data, inject the plaintext into the chaotic system, and generate a ciphertext in combination with the random key stream coefficient; Transmit the ciphertext to the decryption end, synchronize the private key and the switching strategy at the decryption end, and restore the plaintext; Input the restored plaintext into a state feedback controller to generate an anti-saturation control instruction. The state feedback controller includes a nonlinear compensation function.

[0087] Some embodiments of the present application provide a Figure 1 non-volatile computer storage medium for drone control based on a random key stream, storing computer-executable instructions, and the computer-executable instructions are set as: Based on a chaotic system including a main chaotic system and an auxiliary chaotic system, preset a chaotic initial value for the main chaotic system at the encryption end; Select a switching strategy according to the current state components of the main chaotic system to switch the auxiliary chaotic system; Generate a random key stream coefficient through a seed random number generator, combine the random key stream coefficient with the chaotic initial value to obtain a private key; Obtain the plaintext of the aircraft measurement data, inject the plaintext into the chaotic system, and generate a ciphertext in combination with the random key stream coefficient; Transmit the ciphertext to the decryption end, synchronize the private key and the switching strategy at the decryption end, and restore the plaintext; Input the restored plaintext into a state feedback controller to generate an anti-saturation control instruction. The state feedback controller includes a nonlinear compensation function.

[0088] The embodiments in the present application are all described in a progressive manner. The same or similar parts among the embodiments can be referred to each other, and the key points of each embodiment are the differences from other embodiments. In particular, for the embodiments of the Internet of Things devices and media, since they are basically similar to the method embodiments, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiments.

[0089] The system, medium, and method provided by the embodiments of the present application correspond one by one. Therefore, the system and the medium also have beneficial technical effects similar to those of the corresponding method. Since the beneficial technical effects of the method have been described in detail above, the beneficial technical effects of the system and the medium will not be elaborated here.

[0090] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, a system, or a computer program product. Therefore, the present application can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0091] The present application is described with reference to the flowcharts and / or block diagrams of methods, apparatuses (systems), and computer program products according to the embodiments of the present application. It should be understood that each flow and / or block in the flowchart and / or block diagram, as well as the combination of flows and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing devices generate means for implementing the specified functions in Figure 1 one or more flows and / or blocks Figure 1 one or more blocks.

[0092] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer-readable memory generate a manufactured article including instruction means, and the instruction means implement the specified functions in Figure 1 one or more flows and / or blocks Figure 1 one or more blocks.

[0093] These computer program instructions can also be loaded onto a computer or other programmable data processing device, so that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process, and thus the instructions executed on the computer or other programmable device provide steps for implementing the specified functions in Figure 1 one or more flows and / or blocks Figure 1 one or more blocks.

[0094] In a typical configuration, a computing device includes one or more processors (CPUs), an input / output interface, a network interface, and a memory.

[0095] Memory may include non-permanent storage in a computer-readable medium, in the form of random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory is an example of a computer-readable medium.

[0096] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can be implemented using any method or technology to store information. Information can be computer-readable instructions, data structures, program modules, or other data. Examples of computer storage media include, but are not limited to, phase-change RAM (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, compact disc read-only memory (CD-ROM), digital versatile disc (DVD) or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer-readable media does not include transitory computer-readable media such as modulated data signals and carrier waves.

[0097] It should also be noted that the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, commodity, or apparatus that includes a series of elements includes not only those elements but also other elements not explicitly listed, or includes elements inherent to such process, method, commodity, or apparatus. In the absence of further limitations, an element defined by the phrase "comprises a ..." does not exclude the presence of other identical elements in the process, method, commodity, or apparatus that includes the element.

[0098] The foregoing is merely an embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included within the scope of the claims of the present application.

Claims

1. A method for controlling an unmanned aerial vehicle based on a random key stream, characterized in that The method includes: Based on the chaotic system including a main chaotic system and an auxiliary chaotic system, preset a chaotic initial value for the main chaotic system at the encryption end; Select a switching strategy according to the current state components of the main chaotic system to switch the auxiliary chaotic system; Generate a random key stream coefficient through a seed random number generator, and combine the random key stream coefficient with the chaotic initial value to obtain a private key; Obtain the plaintext of the aircraft measurement data, inject the plaintext into the chaotic system, and generate a ciphertext in combination with the random key stream coefficient; Transmit the ciphertext to the decryption end, synchronize the private key and the switching strategy at the decryption end, and restore the plaintext; Input the restored plaintext into a state feedback controller to generate an anti-saturation control command, and the state feedback controller includes a non-linear compensation function.

2. The drone control method based on a random key stream according to claim 1, wherein Select a switching strategy according to the current state components of the main chaotic system to switch the auxiliary chaotic system, specifically including: Based on the auxiliary chaotic system including a first auxiliary system and a second auxiliary system; Calculate the state components of the main chaotic system in real time according to the initial value, and activate the first auxiliary system when the state components are less than a preset value; Activate the second auxiliary system when the state components are greater than a preset value.

3. A method for controlling an unmanned aerial vehicle based on a random key stream according to claim 1, characterized in that, Generate a random key stream coefficient through a seed random number generator, and combine the random key stream coefficient with the chaotic initial value to obtain a private key, specifically including: Use a digital sequence of a preset length as a seed, input the seed into a random number generator to generate the random key stream coefficient; Use the seed as a prefix of the private key, and combine it with the chaotic initial value to obtain the private key.

4. A method for controlling an unmanned aerial vehicle based on a random key stream according to claim 1, characterized in that, Transmit the ciphertext to the decryption end, synchronize the private key and the switching strategy at the decryption end, and restore the plaintext, specifically including: Distribute the seed to the decryption end through a secure channel; Synchronously run the same random number generation algorithm at the encryption end and the decryption end; Synchronously run the main chaotic system according to the chaotic initial value in the private key, and determine the auxiliary chaotic system.

5. A method for controlling a drone based on a random key stream according to claim 1, characterized in that Input the restored plaintext into a state feedback controller to generate an anti-saturation control command, specifically including: Establish a linear state space model of a vertical takeoff and landing fixed-wing aircraft at a preset operating point, and the linear state space model includes an output saturation constraint; Approximate the saturation constraint using a hyperbolic tangent function; Collect the aircraft state vector, and the state vector includes components of position, velocity, attitude angle, and angular velocity; Design a state feedback control law such that the output value of the state feedback controller is the inverse hyperbolic tangent function of the state vector and a preset gain matrix, and the gain matrix is used to make all eigenvalues of the state vector have negative real parts.

6. The method for controlling an unmanned aerial vehicle based on a random key stream according to claim 5, wherein, Design a state feedback control law, and the output value is the inverse hyperbolic tangent function of the state vector and a preset gain matrix, specifically including: Calculate the product of the state vector and the feedback gain parameter to generate an intermediate control vector; Apply the inverse hyperbolic tangent function to each component of the intermediate control vector to obtain an operation result; Output the operation result to an actuator to drive the control surface and the motor.

7. A method for controlling an unmanned aerial vehicle based on a random key stream according to claim 5, characterized in that, After approximating the saturation constraint using the hyperbolic tangent function, the method further includes: Calculate the approximation error between the output value of the hyperbolic tangent function and the saturation constraint, and estimate the upper bound of the approximation error; Inject the upper bound into the state feedback control law to obtain a compensation gain, and adaptively adjust the compensation gain.

8. A method for controlling an unmanned aerial vehicle based on a random key stream according to claim 6, characterized in that The method further includes: Freeze the current control instruction when the number of consecutive decryption failures exceeds the threshold number; Switch to the preset gain matrix and calculate a conservative control instruction according to the preset gain matrix.

9. A drone control device based on a random key stream, characterized in that, The device includes: At least one processor; And a memory communicatively connected to the at least one processor; Wherein, the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can: Based on a chaotic system including a main chaotic system and an auxiliary chaotic system, initialize the main chaotic system through an encryption end to obtain a chaotic initial value; Select a switching strategy according to the current state components of the main chaotic system to switch the auxiliary chaotic system; Generate a random key stream coefficient through a seed random number generator, and combine the random key stream coefficient with the chaotic initial value to obtain a private key; Obtain the plaintext of the aircraft measurement data, inject the plaintext into the chaotic system, and generate a ciphertext in combination with the key stream coefficient; Transmit the ciphertext to a decryption end, synchronize the private key and the switching strategy at the decryption end, and restore the plaintext; Input the restored plaintext into a state feedback controller to generate an anti-saturation control instruction, and the state feedback controller includes a nonlinear compensation function.

10. A non - volatile computer storage medium for drone control based on a random key stream, storing computer - executable instructions, characterized in that, The computer-executable instructions are set to: Based on a chaotic system including a main chaotic system and an auxiliary chaotic system, initialize the main chaotic system through an encryption end to obtain a chaotic initial value; Select a switching strategy according to the current state components of the main chaotic system to switch the auxiliary chaotic system; Generate a random key stream coefficient through a seed random number generator, and combine the random key stream coefficient with the chaotic initial value to obtain a private key; Obtain the plaintext of the aircraft measurement data, inject the plaintext into the chaotic system, and generate a ciphertext in combination with the key stream coefficient; Transmit the ciphertext to a decryption end, synchronize the private key and the switching strategy at the decryption end, and restore the plaintext; Input the restored plaintext into a state feedback controller to generate an anti-saturation control instruction, and the state feedback controller includes a nonlinear compensation function.

Images