Guidance laws based on a conventional sliding mode ensures only asymptotic convergence. However, convergence to the desired impact angle within a finite time is important in most practical guidance applications. These finite time convergent guidance laws suffer from singularity leading to control saturation. In this paper, guidance laws to intercept targets at a desired impact angle, from any initial heading angle, without exhibiting any singularity, are presented. The desired impact angle, which is defined in terms of a desired line-of-sight angle, is achieved in finite time by selecting the interceptor's lateral acceleration to enforce nonsingular terminal sliding mode on a switching surface designed using nonlinear engagement dynamics. Numerical simulation results are presented to validate the proposed guidance laws for different initial engagement geometries and impact angles. Although the guidance laws are designed for constant speed interceptors, its robustness against the time-varying speed of interceptors is also evaluated through extensive simulation results.

Nonsingular Terminal Sliding Mode Guidance with Impact Angle Constraints

Attitude regulation for unmanned quadrotors using adaptive fuzzy gain-scheduling sliding mode control

AIAA Guidance, Navigation, and Control Conference

Pneumatic artificial muscle (PAM) systems are a kind of tube-like actuators, which can act roughly like human muscles by performing contractile or extensional motions actuated by pressurized air. At present, it is still an open and challenging issue to tackle positioning and tracking control problems of PAM systems, due to inherent characteristics, e.g., unidirectional inputs, high nonlinearities, hysteresis, time-varying characteristics, etc. In this paper, a new adaptive control method is proposed for PAM systems, which achieves satisfactory tracking performance. To this end, an update law is designed to estimate unknown system parameters online. Also, some control input transforming operations are applied to address unidirectional constraints (i.e., control inputs of PAM systems should always be positive). As far as we know, compared with most of the existing control methods, this paper gives the first continuous control solution for PAM systems that can simultaneously compensate parametric uncertainties, reject external disturbances, and meet unidirectional constraints. Without linearizing the nonlinear dynamics, the closed-loop system is theoretically proven to be asymptotically stable at the equilibrium point with the stability analysis. In addition, a series of hardware experiments are implemented on a self-built hardware platform, indicating that the proposed method achieves satisfactory tracking control and exhibits robustness against parametric uncertainties and disturbances.

Adaptive Control for Pneumatic Artificial Muscle Systems With Parametric Uncertainties and Unidirectional Input Constraints

Nowadays, it is very important for the success of the determined missions or operations that the Unmanned Aerial Vehicles (UAVs), which are used extensively in the performance of many civil and military tasks, follow the predetermined path with high accuracy at the determined altitude. The fact that the UAV performs its mission by adhering to the predetermined height and path enables the UAV to spend less energy and therefore fly for a longer time. Many traditional control algorithms, especially Proportional-Integral-Derivative (PID), are used in the attitude and altitude control of UAV for path following. Unlike other studies, in this study, metaheuristic optimization algorithms based on swarm intelligence estimate the parameters of the control algorithm proposed for UAV. Using meta-heuristic optimization algorithms such as Particle Swarm Optimization (PSO) and Harris Hawks Optimization (HHO), both attitude and altitude control of the quadrotor have been performed for path following in routes with different geometries such as rectangle, circle, and lemniscate. The performance of each control algorithm in the study for the specified routes has been tested and the test results obtained have been compared with each other. Considering the features such as simplicity, flexibility, ability to search randomly and avoiding local optima, a new control algorithm whose K P , K I , and K D parameter values optimized by HHO, have been proposed for UAV’s attitude and altitude control.

Performance of Metaheuristic Optimization Algorithms based on Swarm Intelligence in Attitude and Altitude Control of Unmanned Aerial Vehicle for Path Following

Continuous second-order sliding mode based impact angle guidance law

The problem of salvo attack of multiple missiles without time-to-go estimation has been addressed by a two-stage guidance scheme in this correspondence. In the first stage, a simple decentralized control law is designed to provide desired initial conditions (target-missile relative range and velocity lead angle) for the latter stage. As for the second stage, all missiles are governed by classical pure proportional navigation guidance law. Numerical simulations under two-dimensional (2-D) and 3-D cases demonstrate the effectiveness of the proposed formulation.

Consensus-Based Two-Stage Salvo Attack Guidance

Impact Angle Constrained Integrated Guidance and Control for Maneuvering Target Interception

In this paper, a robust continuous guidance law with terminal angle constraint for intercepting maneuvering targets in the presence of autopilot lag is proposed and its finite-time stability is proved. First, assuming that the missile autopilot is sufficiently fast, a composite fast nonsingular terminal sliding mode guidance (CFNTSMG) law is presented. The proposed guidance law is obtained through a combination of fast nonsingular terminal sliding mode control theory and generalized disturbance observer (GDOB). The presented guidance law requires no priori information on target maneuver, which is estimated and compensated online by GDOB. Moreover, no discontinuous term exists in CFNTSMG law and therefore chattering is eliminated effectively. Next, viewing the missile autopilot as an uncertain second-order system, an integrated guidance and control dynamics is formulated and the systematic step-by-step backstepping technique is used to derive a new robust guidance law, which not only holds the advantages of CFNTSMG law, but also is insensitive to autopilot lag. At each backstepping step, novel continuous virtual/real control laws using finite-time control approach are designed and tracking differentiator is used to overcome the ‘explosion of complexity’ problem encountered with traditional backstepping method. Theoretical analysis and numerical simulations demonstrate the effectiveness of the proposed method.

Robust terminal angle constraint guidance law with autopilot lag for intercepting maneuvering targets

/pdf/three-dimensional-optimal-impact-time-guidance-for-antiship-27n8pvetac.pdf

Defu Lin

Papers

Continuous second-order sliding mode based impact angle guidance law

Consensus-Based Two-Stage Salvo Attack Guidance

Impact Angle Constrained Integrated Guidance and Control for Maneuvering Target Interception

Robust terminal angle constraint guidance law with autopilot lag for intercepting maneuvering targets

Three-Dimensional Optimal Impact Time Guidance for Antiship Missiles