Correction Projectile Research Articles

Design of Control Strategies for Electric Actuators in 155mm

Abstract The performance of electromagnetic servo actuators as the control execution mechanism for guided projectiles plays a crucial role in the control system of guided projectiles. Due to the limited internal space of correction projectiles and the need to adapt to high-speed rotation, high overload, and small volume environments, the structure, control, and drive circuits of the electromagnetic servo actuators should be miniaturized as much as possible while meeting the requirements and control accuracy. This paper introduces the principle design of the motor drive and control circuit. A permanent magnet synchronous motor is adopted according to the characteristics of the required electromagnetic servo actuators. The model of the permanent magnet synchronous motor is studied, and based on the extended Kalman filter state observer, the estimation of the motor rotor position and speed is conducted. Subsequently, closed-loop vector control simulations of current, speed, and position are performed using Matlab/Simulink to evaluate the control strategy’s effectiveness in actual 155mm correction projectile payloads. This research can provide beneficial reference and guidance for the optimization of electromagnetic servo actuators in practical applications.

Non-Singular Fast Terminal Unidirectional Sliding Mode Control for Fixed Rudder Two-Dimensional Trajectory Correction of Projectile

Abstract This study addresses the control issue of a fixed-rudder two-dimensional trajectory correction projectile. Initially, a novel roll angle controller was designed based on the unidirectional sliding mode theory and the fast terminal sliding mode theory. Subsequently, the system’s response time and robustness were enhanced through the design of a unidirectional sliding mode auxiliary surface and non-singular fast terminal attractor parameters. Finally, the stability of the designed roll angle controller, which meets the system’s stability requirements, was proven using the Lyapunov stability theorem. Simulation verification of the designed controller was conducted using simulation software, and the simulation results indicate that the controller possesses good robustness.

Robust Optimization Design of the Aerodynamic Shape and External Ballistics of a Pulse Trajectory Correction Projectile

To improve the tactical and technical performance of pulse correction projectiles while maintaining stability in uncertain conditions and considering practical engineering constraints, this study performs a multi-objective robust optimization design of the aerodynamic shape and external ballistics of a projectile. The study utilizes an aerodynamic force engineering algorithm and numerical trajectory calculations to obtain the projectile’s performance responses within the Latin hypercube design space. To enhance optimization efficiency, a stochastic Kriging surrogate model is established to capture the inherent uncertainty of limited input data. Ultimately, a Pareto optimal solution for the projectile is obtained using a non-dominated sorting multi-objective sparrow search algorithm. The results of this study demonstrate that the consideration of design uncertainty in the robust optimization of pulse correction projectiles leads to significant enhancements in both lateral correction ability and range while satisfying flight stability requirements. Moreover, when compared to deterministic optimization, the performance variability of the design is markedly improved. This research methodology provides valuable insights for optimizing the performance of pulse correction projectiles.

Characteristic analysis and compensation of eddy current interference field of rotating projectile

The accurate measurement of the attitude of the ballistic correction projectile is the precondition for accurate correction. In order to solve the measurement accuracy problem of the strapdown-connected projectile magnetic sensor, the eddy current magnetic field is considered on the basis of the traditional error compensation model. A simplified mathematical model of the eddy current magnetic field of the pure rolling projectile was established, and the influence of the eddy current magnetic field interference on the magnetic measurement at different rotational speeds was simulated and analyzed. Aiming at the necessity of eddy current magnetic field compensation, a parameter estimation method of the non-independent attitude comprehensive compensation model based on Kalman filter algorithm is proposed. The normalized evaluation of the magnetic correction effect shows that the error of the parameter estimation result does not exceed 0.01%, and the magnetic measurement error after compensation converges to 0.19nT. The compensation effect is obvious and meets the laboratory magnetic measurement compensation requirements.

Design and Parameter Optimization of Trajectory Correction Control Strategy for Air Duct Structure Projectile

In order to make the new air duct structure trajectory correction projectile have good dynamic correction control effect, the control strategy of the projectile’s correction mechanism is studied in this paper. A design method of trajectory correction control strategy based on particle swarm optimization-cuckoo search (PSO-CS) hybrid algorithm is proposed to obtain the optimal control parameters that can make the projectile flight stable and correct accurately. Firstly, the mathematical model of the air duct structure projectile is established. Secondly, the multiobjective optimization problem is analyzed. The projectile’s correction control strategy optimization model is established by taking the start control time, the number of corrections, the correction working time, and the interval time as the control variables. The optimization model innovatively considers the influence of the correction action on the flight stability of the projectile and the influence of the start control time on the correction range. Finally, the PSO-CS hybrid algorithm is used to design the calculation method of the optimization model and solve the optimal correction working parameters. The simulation results indicate that the control strategy optimization model can be solved by the proposed calculation method. Moreover, optimal correction working parameters of the correction mechanism in the current state can be obtained. Compared with the results of using single PSO algorithm and CS algorithm, the correction scheme calculated by PSO-CS hybrid optimization algorithm is better. This correction control scheme can effectively reduce the impact point deviation and make the projectile flight stable. At the same time, the circular error probable (CEP) of the projectile after correction is reduced from 42.3 m to 4.6 m while the impact point dispersion is lowered. The research results show that the design method of correction control strategy proposed in this paper is effective for trajectory correction of the new air duct structure projectile.

An intelligent optimization method of trajectory correction projectile based on design of experiments and stochastic kriging

Performance optimization of a trajectory correction projectile, a type of precision ammunition, is difficult because of complex nonlinear flight characteristics and unique engineering constraints. To reduce the number of repeated tests and iterations, an intelligent optimization algorithm based on the design of experiments (DOE) and response surface methodology (RSM) is presented in the conceptual design of a trajectory correction projectile. Basic projectile aerobody and related design configurations are defined in the initial design stage. Based on DOE, design variables are mapped to the performance criteria to generate a stochastic kriging (SK) response surface. Also, an artificial neural network (ANN) is trained to identify unstable designs. Then, a multi-population genetic algorithm (MPGA) is used to determine the optimal projectile design. The Pareto frontier reflecting the performance tradeoff can be generated by changing its cost function. A detailed is given to illustrate the efficiency of this methodology. The configuration of a trajectory pulse-correction projectile with stabilized fins is optimized based on multiple criteria, maximizing the correction distance while minimizing energy consumption and the angle of attack. Simulations showed that the optimization method proposed could not only be applied to practical engineering problems for trajectory correction projectiles, but also portable for other smart weapons conceptual performance design.

Ballistic and Aerodynamic Characteristics Simulation for Trajectory Correction Projectile

Conventional ammunition easily deviates from the intended target. Its hit probability is reduced by such disturbance factors as fabrication errors, initial muzzle disturbance, initial velocity probable error, and stochastic wind effect. The effect of the above interference factors can be reduced by improving the shooting dispersion, ammunition, and gun or rocket engine structure. However, such improvements may fail to meet the operational requirements for modern warfare. Ballistic correction technique is a proposed trajectory control technique for precision strike with effective damage. Taking a 57mm calibre projectile as research object, trajectory correction projectile with different aerodynamic layouts were designed. The aerodynamic characteristic, static stability, exterior ballistic characteristic and firing density of each projectile has been studied through research method of theoretical analysis and numerical calculation. These findings are considered instrumental in the trajectory correction technology research and engineering application.

Control Strategies for Flight Stability of Trajectory Correction Projectile with Air-Ducts Structure

Aiming at the controllability of spin-stabilized projectile trajectory correction, a new two-dimensional trajectory correction projectile model with a controllable air-ducts structure suitable for the spin-stabilized projectile is proposed in this paper. Furthermore, control strategies of the projectile in the corrected configuration are studied to ensure a stable flight. The correction scheme of the projectile is innovated on the basis of the ram air control mechanism. The air-ducts structure is designed inside the projectile body, and the internal air valve is used to control the lateral air-jet to achieve trajectory correction of the projectile. This is a new two-dimensional trajectory correction scheme with a relatively simple control method. Firstly, the correction mechanism of the new air-ducts structure projectile is analyzed. Secondly, based on the dynamic equation of the projectile, the key parameters of the impulse air valve control, including the safe range of the working pulse width and frequency, are calculated, and the corresponding control strategies are proposed. Finally, the flow field of the projectile in the corrected configuration of the terminal trajectory is numerically simulated, and aerodynamic parameters of the projectile are obtained. Through stability conditions established in this paper and combined with aerodynamic parameters, the validity of the proposed projectile stable flight control strategies is confirmed. The innovations of this paper include: (1) a proposed new aerodynamic configuration model with the air-ducts structure for the spin-stabilized projectile and (2) proposed innovative stable flight control strategies of the corrected configuration projectile. The numerical simulation results show that, compared with the reference projectile without air-ducts structure, the lateral force of the air-ducts structure projectile can produce a radial correction effect on the moving projectile. The simulation results of control strategies indicate that the control strategies can ensure stable flight of the corrected configuration projectile under different conditions.

Correction-Efficiency-Coefficient-Based Trajectory Optimization for Two-Dimensional Trajectory Correction Projectile

Based on the lift-to-drag ratio of a two-dimensional trajectory correction projectile, in this paper, a novel correction efficiency coefficient model has been proposed for the trajectory optimization of a two-dimensional trajectory correction projectile, and research on the influence a correction efficiency coefficient has on the flight parameters of correction trajectory is carried out. A series of results are obtained through theoretical analysis and simulation calculations, indicating that, the smaller the value of the correction efficiency coefficient is, the stronger the correction ability of the projectile reserves. The trajectory and canard geometry of the correction section of the two-dimensional trajectory correction projectile are optimized by the Gauss pseudo-spectral method and correction efficiency coefficient, and, after taking the correction efficiency coefficient into account, the projectile can accurately hit the target and effectively eliminate the swing phenomenon of the projectile’s lateral trajectory. Meanwhile, a stable roll control command is obtained. When the diameter aspect ratio of the canard is 0.4, both the flight state quantity of the optimized projectile and the roll control command are more stable, and, when the canard shape is trapezoidal, the correction efficiency coefficient is smaller, the result of trajectory optimization is more stable, and the stability of the output roll control command is better. The research results of this paper can provide certain references for both the designs of the two-dimensional trajectory correction projectile’s trajectory and the canard geometry.

Research on Parametric Modeling Optimization of Trajectory Correction Projectile Based on FVM

Research on Parametric Modeling Optimization of Trajectory Correction Projectile Based on FVM

Disturbance-Observer-Based Sliding-Mode Attitude Control of Rotation-Isolating Rudder with Ultrasonic Motor

Rotation-isolating rudder is a type of correction mechanism widely used in two-dimensional trajectory correction projectile. In this paper, we focus on its attitude servo system, develop a disturbance-observer-based sliding-mode control method, and prove the asymptotic stability of the control method. Based on the single-axis turntable established, we test the rolling attitude control performance of the rotation-isolating rudder, and the experimental result shows the effectiveness of the control method developed.

Real‐time estimation of roll angle for trajectory correction projectile using radial magnetometers

An adaptive extend Kalman filter（EKF） is designed to estimate the roll angle for trajectory correction projectile only using radial magnetometers. By analysing the characteristics of the radial magnetometer output signal and the complex angular motion of the high-spin projectiles, the measurement equation is established. Two important measures, namely noise parameter adaptation and increasing system observation, are taken to improve the performance of the designed EKF. The novelty of this study is the proposed adaptive EKF has no requirements on the magnetometer measurement accuracy. That is the magnetometers used need not undergo a complicated calibration process. In addition, orthogonal difference method is introduced to adjust noise parameters. Finally, a series of numerical simulations and flight tests are carried out to verify the performance of the proposed method. The results show the designed adaptive EKF can effectively estimate the roll angle for the trajectory correction projectile and could be extended to practical engineering applications.

Study on RLS-Type Algorithm of GPS-Guided Range Correction

Mitigating the error of GPS measurement signals is essential for the range precision of GPS-guided range correction projectile. In order to improve the range precision, an online method based on recursive least square algorithm (RLS) is applied to calculate the deployment time of brake. First, RLS is utilized to mitigate the error of the velocity, position, angle, etc., measured by GPS. Then, the deployment time can be calculated accurately by means of the appropriate pretreated data. To confirm the effectiveness of the method, a comparison to using least square algorithm and non-algorithm is done. The experimental results demonstrate that the method in this paper takes advantages in terms of online, real-time and the range correction accuracy.

Design of a 40mm Caliber Ballistic Correction Steering Gear System

The ballistic correction projectile uses several limited open-loop corrections to reduce the error of the projectile flight or the deviation of the projectile from the target due to the target movement, thereby reducing the projectile dispersion error and improving the hit rate. This paper draws on the existing advanced steering gear design, and improves the rudder blade airfoil and its plane shape according to the flight speed of the ballistic correction projectile (Mach 2). Through the analysis of degrees of freedom, a pair of limit devices have been added to the housing to make the servo system work more stable and efficient. At the end of the paper, the conclusion that the 5V voltage is better than the 3.3V power supply is obtained through the control experiment. The safety and reliability of the servo system are further verified by the anti-torque simulation of the cam mechanism and the anti-overload simulation of the servo motor.

Design of Attitude Controller of Two-Dimensional Correction Projectile Based on UAS-SMC Method

For the spin stabilized two-dimensional trajectory correction projectiles with utation and precession phenomenon, an attitude controller with sliding mode control method and unidiational auxilairy surfaces (UAS-SMC) is proposed in this paper. And the underactuated control allocation in two-dimensional trajectory correction projectile with UAS-SMC controller is also discussed here. Simulation results show that the proposed controller can effectively control the attitude of the projectile and has strong robustness, which provides reference for engineering applications.

Accuracy Analysis of Aerodynamic Calculation of Twodimensional Ballistic correction Projectile based on Missile Datcom

Missile Datcom (hereinafter referred to as Datcom) is an aerodynamic engineering calculation software developed by the US Air Force Research Laboratory. It is commonly used in the preliminary design of the shape scheme of missiles, aircraft and other aircraft. In this paper, Datcom is used to calculate the aerodynamic parameters of a two-dimensional ballistic correction projectile(D2BCP), and the calculated data is compared with the wind tunnel test data. The analysis results show that Datcom calculates the axial force coefficient (CA) of the projectile with large system deviation, however, the deviation can be eliminated by a certain compensation, thereby obtaining a more accurate CA of the projectile. Datcom calculates the normal force coefficient (CN) with high Mach number accuracy, but there is an unacceptable deviation of the projectile CN calculated at small angle of attack ( α ). The calculation of pitching moment coefficient with α (CMa) is higher, but the error is larger under individual Mach numbers.

Research on Evaluation Methods of Firing Precision of Trajectory Correction Projectile

As a new type of ammunition, the trajectory correction projectile has much different ballistic characteristics than traditional uncontrolled ammunition and missile. The firing precision of trajectory correction projectile is significantly higher than that of uncontrolled projectile and lower than missile. Also the evaluation method for firing precision is different from that of uncontrolled projectile and missile. In this paper, by analyzing the calculation methods and characteristics of different firing precision evaluation indicators, the method suitable for evaluating the precision of trajectory correction projectile is determined, which provides theoretical and technical support for acceptance of trajectory correction projectile firing precision.

Research on Instability Boundaries of Control Force for Trajectory Correction Projectiles

The balance of stability and maneuverability is the foundation of the trajectory correction projectile. For the terminal correction projectile without an attitude feedback loop, a larger control force is expected which may cause an instability. This paper proposes a novel method to derive instability boundaries for the control force magnitude. No additional coordinate system is needed in this method. By introducing the concept of angular compensation matrix, the exterior ballistic linearized equations considering control force are established. The necessary prerequisite for a stable flight under control is given by the Routh stability criterion. The instability boundaries for the control force magnitude are derived. The results of example flights are 13.5% more accurate compared with that in relevant research. Numerical simulations demonstrate that if the control force magnitude lies in the unstable scope derived in this paper, the projectile loses its stability. Furthermore, the effects of the projectile pitch, velocity, and roll rate on flight stability during correction are investigated using the proposed instability boundaries.

Roll Angle Measurement for a Spinning Vehicle Based on GPS Signals Received by a Single-Patch Antenna.

Roll angle measurement is an essential technology in the trajectory correction projectiles. In this paper, an algorithm to detect the roll angle and rotational speed of a spinning vehicle is studied by using a GPS (Global Positioning System) receiver with a single side-mounted antenna. A Frequency-Locked Loop (FLL) assisted Phase-Locked Loop (PLL) is designed to obtain the attitude information from GPS signals, and the optimal parameters of this system are discussed when different rotational speeds are considered. The error estimation of this method and signal-to-noise ratio analysis of GPS signals are also studied. Finally, experiments on the rotary table were carried out to verify the proposed method. The experimental results showed that the proposed algorithm can detect the roll angle in a precision of within 5 degrees.

Research on Roll Control System for Fixed Canard Rudder of the Dual-Spin Trajectory Correction Projectile

The characteristics of high-spin, high-load and wide-range of the dual-spin trajectory correction projectile are the main design difficulties of the fixed canard rudder roll control system. Permanent magnet alternating generator within the limited space, which integrates the battery and rudder, as well as its driving and measuring system is designed based on the high-spin and dual-spin characters. Meanwhile, based on the analysis of structure and operating principle, the triple closed-loop roll control system based on parallel processors is proposed, and then the signals under strong interference are processed, completing the roll attitude solution within the whole scope of trajectory. A semi-physical simulation system is built to complete control experiments with the air torque respectively provided by torque motor and wind tunnel. The wireless transmission module has also been equipped to realize real-time display of the measured roll data on the terminal computer. The responding time is less than 0.7 s and the control precision is within ± 5°. It’s proved that the designed generator provides needful torque for control and also power supply for whole electrical circuits, saving both space and cost. It is also demonstrated that the proposed triple closed-loop roll control system has good feasibility, reliability and value in engineering application.