Abstract-Sina is a robotic telesurgery system that accepts and works with conventional laparoscopic tools at its endeffector. This paper describes the design and analysis of an adapting mechanism for Sina, to enable manipulating a manual wristed laparoscopic instrument, i.e., Laparo-Angle by the system. After identification of the kinematics and dynamics characteristics of Laparo-Angle experimentally, .the design considerations of the adapting mechanism, including compatibility with the instrument (at one side) and the host robotic arm (at the other side), required kinematics and dynamics features, ease of tool replacement, etc., were studied and a conceptual design, based on the Agile Eye mechanism, was proposed. The forward and inverse kinematics analysis of the proposed mechanism revealed that it is capable of providing the desired workspace while meeting the design constraints. The workspace of the mechanism was a cone with an apex angle of 35 degrees, in which both the isotropy and manipulability indices were satisfying. The condition number and the Jacobean determinant of the mechanism within its workspace were lower than 1.4 and higher than 1, respectively. In general, the proposed mechanism was found to could satisfy the design requirements and constrains.

Optimal hyperplastic coe cients of the micromechanical constituents of the human brain stem were investigated. An evolutionary optimization algorithm was combined with a Finite Element (FE) model of a Representative Volume Element (RVE) to nd the optimal material properties of axon and Extra Cellular Matrix (ECM). The tension and compression test results of a previously published experiment were used for optimizing the material coe cients, and the shear experiment was used for the validation of the resulting constitutive model. The optimization algorithm was used to search for optimal shear moduli and ber sti ness of axon and ECM by tting the average stress in the axonal direction with the results of the experiment. The resulting constitutive model was validated against the shear stress results of the same experiment, showing strong agreement. The instantaneous shear moduli and ber sti ness of both axon and ECM increased at higher strain rates, while the axon-to-ECM shear modulus ratio decreased from the value of 10 at a strain rate of 0.5/s to the value of 5 at a strain rate of 30/s. The proposed characterization procedure and the resulting coe cients may be applied to future multi-scale FE studies of the human brain.

SUMMARYIn this paper, we study the kinematic effects of number of legs in 6-DOF UPS parallel manipulators. A group of 3-, 4-, and 6-legged mechanisms are evaluated in terms of the kinematic performance indices, workspace, singular configurations, and forward kinematic solutions. Results show that the optimum number of legs varies due to priorities in kinematic measures in different applications. The non-symmetric Wide-Open mechanism enjoys the largest workspace, while the well-known Gough–Stewart (3–3) platform retains the highest dexterity. Especially, the redundantly actuated 4-legged mechanism has several important advantages over its non-redundant counterparts and different architectures of Gough–Stewart platform. It has dramatically less singular configurations, a higher manipulability, and at the same time less sensitivity. It is also shown that the forward kinematic problem has 40, 16, and 1 solution(s), respectively for the 6-, 3-, and the 4-legged mechanisms. Superior capabilities of the 4-legged mechanism make it a perfect candidate to be used in more challenging 6-DOF applications in assembly, manufacturing, biomedical, and space technologies.

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<div>Replacement of the exclusively designed instruments of the robotic surgery systems with the commercial hand-held wristed instruments provides advantages such as single-usability and cost reduction. A 4-DOF robotic system, based on a modified non-symmetric 2-DOF agile-eye mechanism, was developed to manipulate the hand-held wristed instruments. The kinematics of the mechanism was analyzed, its dimensions were optimized, and a functional prototype was tested experimentally. The optimized mechanism had a great kinematic isotropy (condition number <1.31) in the target workspace. Experimental studies revealed a high tracking accuracy ($0.27 +- 0.01 deg rms for the worse case) and a reasonably acceptable compliance (0.19 deg/N.m and 0.45 deg/N.m for the first and second kinematic chains respectively). By satisfying the design requirement, the robotic manipulator provides an attractive choice for robotic surgery systems. The performance of the manipulator can be improved further by increasing the stiffness of the second kinematic chain and performing kinematic calibration.</div>