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This article proposes a leader–follower cooperative salvo guidance strategy to intercept nonmaneuvering targets by exploiting the advantages of supertwisting sliding mode control. An improved estimate of time-to-go, that does not assume interceptor's small heading angle, is used in the guidance design. This allows the guidance strategy to remain effective even for large initial heading of the interceptor. Under the action of supertwisting control, the error in impact time settles precisely to zero in finite time. The proposed guidance strategy provides robustness against uncertainties and a smooth control signal, along with finite-time convergence of error. The guidance performance has been shown for one-to-one engagement, and in a cooperative framework, to achieve a salvo in a predetermined time. Numerical simulations are presented for various engagement scenarios to aid the analysis, and illustrate the efficacy of the proposed guidance scheme, even under noisy environment. [ABSTRACT FROM AUTHOR]

Continuous Stirred Tank Reactors (CSTR) are the most important and central equipment in many chemical and biochemical industries, that exhibit second order complex nonlinear dynamics. The nonlinear dynamics of CSTR poses many design and control challenges. The proposed controller guarantees a stable closed loop behavior over multiple operating points even in the presence of perturbations and parametric anomalies. An event driven sliding mode control is presented in this work to regulate the temperature and concentration states very close to the equilibrium points of a CSTR. The control is executed only when a predefined condition gets violated and hence, the controller is relaxed when the system is operating under tolerable limits of closed loop performance. A novel dynamic event triggering rule is presented to maintain desired performance with minimum computational cost. The inter event execution time is shown to be lower bounded by a finite positive quantity to exclude Zeno behavior. Sliding mode control (SMC) combined with event triggering scheme retains the inherent robustness of traditional SMC and aids in reducing computational load on the controller involved. Simulation results validate the efficiency of the proposed controller. [ABSTRACT FROM AUTHOR]

This paper proposes integrated guidance and control design to intercept a target, which may execute various motions, at a pre-specified time of interception. The problem is addressed considering nonlinear engagement kinematics and the interceptor is steered using the combined effects of canard as well as tail configurations (dual-controlled interceptors). Different formulations of time-to-go, without the restrictive assumption of interceptor's small heading angle, have been used in deriving the guidance commands, allowing the proposed strategy to remain effective over a wide range of impact time values. A weighted effort allocation scheme, in canard and tail deflections, has been proposed to generate the required lateral acceleration. The overall design uses sliding mode control owing to its simplicity of design, while a nonlinear finite-time disturbance observer is used to estimate the target's maneuver. Finally, simulations are presented for various target motions, and time-constrained interception with an impaired actuator is also shown, vindicating the efficacy of the proposed technique. [ABSTRACT FROM AUTHOR]

This paper deals with nonsingular guidance and control design for an interceptor, using a decoupled approach, steered by the combined effects of both canard and tail, to intercept a moving but non-maneuvering target at a time specified a priori. First, interceptor's desired lateral acceleration, consisting of nominal and corrective components, is derived using deviated pursuit guidance. While the nominal component is the pursuit guidance law, the corrective component drives the time-to-go error to zero within a finite-time in an optimal manner. Using a desired error dynamics and a meaningful performance index, the lateral acceleration demand is minimized during the transient phase. With exact knowledge of time-to-go and the consideration of nonlinear kinematic model, the proposed design circumvents the errors arising out of any approximations. Interceptor's canard and tail deflection commands are derived using predefined-time convergent sliding mode control, which allows the autopilot to precisely track the commanded lateral acceleration within a time specified during design. Finally, simulations are presented for various cases to demonstrate the efficacy of the proposed design. [ABSTRACT FROM AUTHOR]