A seeker system is the target detection mechanism of a missile. It consists of a two axis gimbal system with an optical sensing device as pay load. The estimation approach is required for the angular position and disp...
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A seeker system is the target detection mechanism of a missile. It consists of a two axis gimbal system with an optical sensing device as pay load. The estimation approach is required for the angular position and displacement rates of the seeker pitch and yaw gimbals. The performance of seeker is affected by cross coupling between the two gimbals and the external disturbance. This paper presents estimation of the lumped disturbance term in each channel using higher order sliding modes (HOSM). The lumped disturbance is considered as additional state to formulate extended state system. HOSM Estimator is designed for the extended state system. The effectiveness of the method is validated in simulations. The advantage of HOSM observer over Sliding Mode Observer (SMO) with respect to instability for increased initial conditions is validated in simulation.
This paper considers the problem of controlling relative attitude between two spacecrafts, so as to follow a smoothly time varying desired relative attitude trajectory. The spacecrafts are modelled as rigid bodies and...
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This paper considers the problem of controlling relative attitude between two spacecrafts, so as to follow a smoothly time varying desired relative attitude trajectory. The spacecrafts are modelled as rigid bodies and attitudes are represented in non-linear state space of SO(3). The attitude control law proposed does not need relative attitude measurement and is determined from line of sight (LOS) unit vectors measured by spacecrafts to each other and from each spacecraft to a common object in respective body fixed frames. Unlike existing control laws using LOS measurements, positions of spacecrafts are not considered fixed. The state feedback laws proposed in this work guarantee almost global asymptotic tracking of the desired time varying attitude trajectory, when positions of spacecrafts do not become collinear or coincide. The simulation results of the proposed control law are also shown.
We consider an optimal control problem for a vibrating string with multiplicative distributive control. Multiplicative control is the coefficient u ( x, t ) of velocity term y t . Using multiplicative control, we brin...
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We consider an optimal control problem for a vibrating string with multiplicative distributive control. Multiplicative control is the coefficient u ( x, t ) of velocity term y t . Using multiplicative control, we bring the state solution to the desired profile under a quadratic cost of *** prove the existence of optimal control. Criterion for characterization of the unique optimal control is provided in the form of optimality system.
This paper presents a coordination algorithm for mobile autonomous robots. Relying on distributed sensing, the robots achieve rendezvous, i.e., they move to a common location. Each robot is a point mass moving in a si...
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This paper presents a coordination algorithm for mobile autonomous robots. Relying on distributed sensing, the robots achieve rendezvous, i.e., they move to a common location. Each robot is a point mass moving in a simply connected, nonconvex, unknown environment according to an omnidirectional kinematic model. It is equipped with line-of-sight limited-range sensors, i.e., it can measure the relative position of any object (robots or environment boundary) if and only if the object is within a given distance and there are no obstacles in between. The perimeter minimizing algorithm is designed using the notions of robust visibility, connectivity-preserving constraint sets, and proximity graphs. The algorithm provably achieves rendezvous if the interagent sensing graph is connected at any time during the evolution of the group. Simulations illustrate the theoretical results and the performance of the proposed algorithm in asynchronous setups and with measurement errors, control errors, and nonzero robot size. Simulations to illustrate the importance of visibility constraints and comparisons with the optimal centralized algorithm are also included.
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