Design of a constant-voltage and constant-current controller with dual-loop and adaptive switching frequency control

A 5.0-V 2.0-A flyback power supply controller providing constant-voltage （CV） and constant-current （CC） output regulation without the use of an optical coupler is presented. Dual-close-loop control is proposed here due to its better regulation performance of tolerance over process and temperature compared with open loop control used in common. At the same time, the two modes, CC and CV, could switch to each other automatically and smoothly according to the output voltage level not sacrificing the regulation accuracy at the switching phase, which overcomes the drawback of the digital control scheme depending on a hysteresis comparator to change the mode. On-chip compensation using active capacitor multiplier technique is applied to stabilize the voltage loop, eliminate an additional package pin, and save on the die area. The system consumes as little as 100 mW at no-load condition without degrading the transient response performance by utilizing the adaptive switching frequency control mode. The proposed controller has been implemented in a commercial 0.35μm 40-V BCD process, and the active chip area is 1.5×1.0 mm^2. The total error of the output voltage due to line and load variations is less than 4-1.7%.

Improvisation of Node Mobility Using Cluster Routing-based Group Adaptive in MANET

In today's Internet routing infrastructure,designers have addressed scal-ing concerns in routing constrained multiobjective optimization problems examining latency and mobility concerns as a secondary constrain.In tactical Mobile Ad-hoc Network(MANET),hubs can function based on the work plan in various social affairs and the internally connected hubs are almost having the related moving standards where the topology between one and the other are tightly coupled in steady support by considering the touchstone of hubs such as a self-sorted out,self-mending and self-administration.Clustering in the routing process is one of the key aspects to increase MANET performance by coordinat-ing the pathways using multiple criteria and analytics.We present a Group Adaptive Hybrid Routing Algorithm(GAHRA)for gathering portability,which pursues table-driven directing methodology in stable accumulations and on-request steering strategy for versatile situations.Based on this aspect,the research demonstrates an adjustable framework for commuting between the table-driven approach and the on-request approach,with the objectives of enhancing the out-put of MANET routing computation in each hub.Simulation analysis and replication results reveal that the proposed method is promising than a single well-known existing routing approach and is well-suited for sensitive MANET applications.

Adaptive Multiantenna Technology

Abstract： Multiantenna technology can be implemented in several modes. These modes have varying characteristics and are used in different scenarios. This paper introduces Beamforming （BF）, Cyclic Delay Diversity （CDD）, Spatial Diversity （SD）, Spatial Multiplexing （SM）, and other multiantenna technologies. It also analyzes various technical features and their application scenarios. An adaptive multiantenna switching algorithm is proposed that chooses a suitable mode for sending data according to the scenario or wireless channel conditions. This switching algorithm improves multiantenna technology and enhances the quality of wireless network communications

Continuous adaptive gaits manipulation for three-fingered robotic hands via bioinspired fingertip contact events

The remarkable skill of changing its grasp status and relocating its fingers to perform continuous in-hand manipulation is essential for a multifingered anthropomorphic hand.A commonly utilized method of manipulation involves a series of basic movements executed by a high-level controller.However,it remains unclear how these primitives evolve into sophisticated finger gaits during manipulation.Here,we propose an adaptive finger gait-based manipulation method that offers real-time regulation by dynamically changing the primitive interval to ensure the force/moment balance of the object.Successful manipulation relies on contact events that act as triggers for real-time online replanning of multifinger manipulation.We identify four basic motion primitives of finger gaits and create a heuristic finger gait that enables the continuous object rotation of a round cup.Our experimental results verify the effectiveness of the proposed method.Despite the constant breaking and reengaging of contact between the fingers and the object during manipulation,the robotic hand can reliably manipulate the object without failure.Even when the object is subjected to interfering forces,the proposed method demonstrates robustness in managing interference.This work has great potential for application to the dexterous operation of anthropomorphic multifingered hands.

Secure state estimation for cyber-physical systems with unknown input sliding mode observer

In recent years, cyber attacks have posed great challenges to the development of cyber-physical systems. It is of great significance to study secure state estimation methods to ensure the safe and stable operation of the system. This paper proposes a secure state estimation for multi-input and multi-output continuous-time linear cyber-physical systems with sparse actuator and sensor attacks. First, for sparse sensor attacks, we propose an adaptive switching mechanism to mitigate the impact of sparse sensor attacks by filtering out their attack modes. Second, an unknown input sliding mode observer is designed to not only observe the system states, sensor attack signals, and measurement noise present in the system but also counteract the effects of sparse actuator attacks through an unknown input matrix. Finally, for the design of an unknown input sliding mode state observer, the feasibility of the observing system is demonstrated by means of Lyapunov functions. Additionally, simulation experiments are conducted to show the effectiveness of this method.

Adaptive robust control of nonholonomic systems with stochastic disturbances

This paper deals with nonholonomic systems in chained form with unknown covariance stochastic disturbances The objective is to design the almost global adaptive asymptotical controllers in probability Uo and u1 for the systems by using discontinuous control. A switching control law Uo is designed to almost globally asymptotically stabilize the state x0 in both the singular Xo（t0）=0 case and the non-singular Xo（to）≠O case. Then the state scaling technique is introduced for the discontinuous feedback into the （x1, x2,…, xn）-subsystem. Thereby, by using backstepping technique the global adaptive asymptotical control law u1 has been presented for （x1, x2, …, xn） -subsystem for both different Uo in non-singular x0 （t0）≠0 case and the singular case X0 （t0）=0. The control algorithm validity is proved by simulation.

Efficient optimization method for variable-specific-impulse low-thrust trajectories with shutdown constraint

This paper develops a sequential convex programming(SCP)-based method to solve the minimum-fuel variable-specific-impulse low-thrust transfer problem considering shutdown constraint,with emphasize on improving the computational efficiency.The variable parameter engine is more applicable for many low-thrust scenarios,therefore,both a continuously variable model and a ladder variable model are adopted.First,the original problem is convexified by processing the constraint feasible domain,which is composed of the nonlinear dynamic equations and second-order equality constraint,into convex sets.Then,the approximation is generated to close the optimal solution of the low-thrust problem by iteratively solving the convexified subproblem.Moreover,the switching self-detection and adaptive node refinement methods are presented,which can improve the accuracy of the solution and accelerate the convergence during the approximation process and is especially necessary and effective in the scenarios with shutdown constraint.In numerical simulations,the comparison with the homotopic approach shows that the proposed method only needs 4%computational time as that of the homotopic approach,and two variable-specificimpulse examples further demonstrate the effectiveness and efficiency of the proposed method.