This paper proposes the use of Legendre pseudospectral method (PSM) to obtain the optimal guidance strategy for a two-dimensional interceptor problem. An optimal control problem is formulated that addresses the conflicting objective of minimizing the energy usage, along with minimizing the time taken by missile to capture the target. The PSM-based guidance strategy is compared with other conventional guidance laws such as pure proportional navigation (PPN) guidance law and also evolutionary algorithm inspired differential evolution tuned proportional navigation (DEPN) guidance law. A scheme by which the PSM guidance strategy can be applied online is also included in this paper. The cost function value and the interception time indicates the superiority of the PSM-based guidance strategy.

Last few decades have witnessed a rapid development in robotic technology. Different types of intelligent machines which facilitate various tasks in industry environment are becoming popular. This paper focuses on designing a low cost coconut tree climbing and harvesting robot. The kinematics and the motion of the robot are designed by referring to the motion of coconut harvester. The robot consists of two segments joined by a pair of threaded rods coupled to motors. The mechanical frame is designed in draft sight software and is implemented using aluminum segments and threaded rods. It has two arms driven by motors for holding. Locomotion of the robot is achieved using six motors out of which four motors are used in two hands and other two are used for upward and downward motion. The other part is a robotic arm for cutting down the coconuts. The robotic arm is attached on top of the climbing part. The operation of the cutting arm is done manually from the ground using a remote. The robot is automated using Arduino-Uno, motor H-bridge drivers, current and level sensors and other supporting circuits. The forward and the reverse motion of the motors are controlled by the Arduino through driver modules. Robot has automatic and manual functions fully controlled by the end-user. This paper has taken into account of the safety, reliability and the ease of use. A locomotion algorithm is developed to provide the robot with an autonomous capability for climbing. The prototype of the robot is implemented and tested successfully.

No abstract

No abstract

This article considers the problem of attitude regulation of rigid spacecraft under the effect of inertial ambiguity, exogenous disturbances, input saturation, and actuator uncertainties. In this regard, an adaptive second‐order sliding mode control (ASOSMC) is designed to provide robustness against the lumped disturbances (the combination of uncertainties and faults). The ASOSMC presents a two‐fold advantage over conventional SMC. The use of adaptive law eliminates the assumption of a priori knowledge on the upper bounds of the disturbances. Further, the SOSMC methodology alleviates the high‐frequency chattering in the input without compromising robustness. The theoretical analysis under the proposed strategy guarantees the convergence of sliding surface and system states to the origin in a finite‐time. Besides, this work also resolves the inbuilt problem of unwinding in the quaternion‐based attitude representation. Further, the nominal parameters of the proposed control law are optimized offline using an ant lion optimization method. The numerical simulation validates the effectiveness of the proposed controller by comparing its performance with the other existing controllers.