This article addresses an efficient and novel method for singularity-free path planning and obstacle avoidance of parallel manipulator based on neural networks. A modified 4-5-6-7 interpolating polynomial is used to plan a trajectory for a spherical parallel manipulator. The polynomial function which is smooth and continuous in displacement, velocity, acceleration and jerk is used to find a path avoiding obstacles and singularities. The polynomial is further modified to plan a trajectory with minimum passing length through the obstacle and singularity, and the best kinematics conditioning index, as well. An artificial neural network is implemented to solve forward kinematics of the manipulator to estimate the distance between gripper and singularity or obstacle in Euler coordinate. Moreover, the simulation results prove the efficiency of the proposed algorithm. پرونده مقاله

In this paper, the free vibration response of a laminated composite rectangularplate supporting a rotating circular patch mass is studied. The two variable refined platetheory that employs only two unknown functions as against three in the case of simpleshear deformation theory is applied to define the third order displacement field of acomposite rectangular plate. The plate is considered to have simply supported boundaries.The equations of motion for the rectangular plate are obtained by calculus of variation. Dueto significance of the fundamental frequency of the plate, its variation with respect to thenon-dimensional geometrical parameters such as aspect ratio of the plate, size and locationof the rotating patch mass, is investigated. It will be shown herein that the proposed theoryis simple in solving the free vibration problems of plates with patch masses. پرونده مقاله