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SUMMARYThis paper presents a solution for optimal trajectory planning problem of robotic manipulators with complicated dynamic equations. The main goal is to find the optimal path with maximum dynamic load carrying capacity (DLCC). Proposed method can be implemented to problems of both motion along a specified path and point-to-point motion. Dynamic Programming (DP) approach is applied to solve optimization problem and find the positions and velocities that minimize a pre-defined performance index. Unlike previous attempts, proposed method increases the speed of convergence by using the sequential quadratic programming (SQP) formulation. This formulation is used for solving problems with nonlinear constraints. Also, this paper proposes a new algorithm to design optimal trajectory with maximum DLCC for both fixed and mobile base mechanical manipulators. Algorithms for DLCC calculations in previous works were based on indirect optimization method or linear programming approach. The proposed trajectory planning method is applied to a linear tracked Puma and the mobile manipulator named Scout. Application of this algorithm is confirmed and simulation results are compared with experimental results for Scout robot. In experimental test, results are obtained using a new stereo vision system to determine the position of the robot end-effector.

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In this paper, a scalar two-dimensional analysis was conducted on the influence of nanoparticles on the thawing and freezing rate of phase-change materials based on enthalpy method that is an innovative calculation method. To this end, carbon nanotubes (CNTs) and aluminum oxide nanoparticles (NPs) were employed as a model of cylindrical and spherical nanoparticles, respectively.Paraffin and a composite of hydrated salts was also utilized as the PCM. The numerical procedure involved the simulation of the phase change process based on finite difference using enthalpy approach. Because of the recent innovations in computer calculation and also its connection with mechanical engineering a computational code was written for this purpose.Simulation results indicated a reduction in time of thawing and freezing upon incorporation of nanoparticles into the phase change material. For both states, CNTs showed the better result due to acceleration of the heat transfer. The biggest increase (28%) in the rate of thawing and freezing was for CNT-paraffin system; while the lowest increase (6%) was observed in aluminum oxide-hydrated salt system. This result can be utilized to control the speed of energy storage and release.