فهرست مطالب omid koochakianfard

This paper aims to achieve real-time optimum push recovery and high-speed pattern generation for a 3D humanoid robot.  For this purpose, a divergent component of motion (DCM) based locomotion is planned using a three-mass inverted pendulum model. To improve push recovery robustness in the presence of strong disturbances during walking, a quadratic optimization strategy algorithm is introduced, including weighted step time adaption, step position adjustment, and ankle strategy. The minimum error push recovery cost function is obtained through quadratic programming. To validate our proposed model different scenarios for real-time navigation of robot considering strong disturbances in various speeds of walking from 0/8 to 1/6 meters per second are analyzed. The verification methods indicate that the proposed method recovered from 34.5 N.s disturbances at 1/6 meters per second speed, while conventional push recovery methods guaranteed lower speeds robust stable locomotion in the same disturbances. In this paper, a real humanoid robot and actual physical conditions were considered for validation of navigation and robust optimum push recovery.

This paper analyzes the size-dependent vibration of nanoscale beams with simultaneously longitudinal and rotational motions based on nonlocal theory for the optimum design of nanoscale surgical robots. Also, for the first time, a parametric study is performed to explain the surface effects, viscoelastic-Pasternak foundations characteristics, thermal loads, geometric properties, symmetric and asymmetric cross-sections, axial and follower loads on the dynamics and stability of the system. Adopting the Galerkin discretization approach, the reduced-order dynamic model of the system is acquired. Also, analytical and numerical methods are exploited. To ensure the accuracy of the proposed model and method, the present study results are compared and validated with those of published articles. Stability maps and Campbell diagrams are drawn for different working conditions. The results showed that increasing the surface elastic modulus and residual stress improves the vibration frequencies and dynamic instability threshold. It is also found that with increasing system thickness/length, the axial velocity of static instability decreases/increases. In addition, it is observed that the system performance improves with increasing the elastic and shear coefficients of the foundation. The results of the present study significantly help designers and engineers control the vibration of bi-gyroscopic nanoscale robots.