Mobile Robot Utilizing Arm Rotations – Performance of Mobile Robot Under a Gravity Environment –

In this research, we have considered a mobile robot that can start to move by utilizing rotations of the two arms. This robot consists of two rotating arms and a body. Additionally, it has a device that can fix the body to a platform constructed on a certain wall or floor. In our previous study, we investigated the performance of a robot that could move in a planar space without friction or gravity through several numerical simulations. In this study, we investigate the performance of the mobile robot under a gravity environment. While the body is fixed to a starting platform, the mobile robot can store kinetic energy by rotating its arms. When the body is released from the starting platform, the mobile robot hops to the subsequent platform. We consider a scheme to control the hopping direction of the mobile robot and a scheme to reduce the collision impact against the subsequent platform. Thereafter, we verify the feasibility of the proposed schemes through numerical simulations.

Minimum Base Attitude Disturbance Planning for a Space Robot During Target Capture

This paper presents a method to minimize the base attitude disturbance of a space robot during target capture. First, a general dynamic model of a free-floating space robot capturing a target is established using spatial operator Algebra, and a simple analytical formula for the base angular velocity change during the impact phase is obtained. Compared with the former models proposed in the literature, this model has a simpler form, a wider range of applications, and O(n) computation complexity. Second, based on the orthogonal projection matrix lemma, we propose the generalized mass Jacobian matrix (GMJM) and find that the base angular velocity change is a constant multiple of the component which the impact impulse projects to the column space of the GMJM. Third, a new concept, the base attitude disturbance ellipsoid (BADE), is proposed to express the relationship between the base attitude disturbance and the impact direction. The impact direction satisfying the minimum base attitude disturbance can be straightforwardly obtained from the BADE. In particular, for a planar space robot, we draw the useful conclusion that the impact direction unchanged base attitude must exist. Furthermore, the average axial length of the BADE is used as a measurement to illustrate the average base attitude disturbance under impact impulses from different directions. With this measurement, the desired pre-impact configuration with minimum average base attitude disturbance can be easily determined. The validity and the efficiency of this method are verified using a three-link planar space robot and a 7DOF space robot.

Role of topological scale in the differential fouling of Pseudomonas aeruginosa and Staphylococcus aureus bacterial cells on wrinkled gold-coated polystyrene surfaces

Wrinkled patterns, which possess an extensive surface area over a limited planar space, can provide surface features ranging across the nano- and microscale.

Assessment to Iceberg Impact Loads to Fixed Structures in Multi-Planar Space

This paper investigates the iceberg impact force to fixed structures in multi-planar space (3D). The global and local impact mechanics are discussed in details. The global impact energy is calculated by considering the eccentricities of iceberg in multi-planar space considering the tangential impact momentum. Thus, the impact phenomenon in a detailed manner could be assessed, such as the influences of friction and structural inclination to impact loads et.al.. It is found that the dissipated energy during an impact does not depend on the local stiffness within the contact area. Meanwhile, the impact force and duration are linked to the local stiffness. A semi-integrated analysis has been demonstrated to approach the local deformations of structure and iceberg. The structure and ice deformation could be simplified as linear/nonlinear springs. The ice pressure-area relationship and the force-deformation curve are used respectively to approach the local deformation. The methodology proposed here shows excellent agreement with previous work in planar case (2D). Sensitivity studies have been performed both to global and local mechanics. Conclusions and summaries have been included.