This paper introduces a tactile rendering algorithm for wearable cutaneous devices that stimulate the skin through local contact surface modulation. The first step in the algorithm simulates contact between a skin model and virtual objects, and computes the contact surface to be rendered. The accuracy of this surface is maximized by simulating soft skin with its characteristic nonlinear behavior. The second step takes the desired contact surface as input, and computes the device configuration by solving an optimization problem, i.e., minimizing the deviation between the contact surface in the virtual environment and the contact surface rendered by the device. The method is implemented on a thimble-like wearable device.

In this paper, we extend the concept of dynamic manipulability to evaluate the dynamic property of multifingered grasping systems consisting of a multifingered hand and a grasped object, and propose a measure of dynamic manipulability of multifingered grasping. Similar to the original dynamic manipulability, the proposed measure evaluates the mapping from a set of realizable joint torques to a set of resultant accelerations of the grasped object, which forms an ellipsoid under a constant internal force constraint. It is clearly shown that the internal forces not only affect the volume of the ellipsoid, but also the amount of offset of the ellipsoid, while the gravity forces simply induce an offset. A new measure, i.e., omnidirectionality, is introduced to add a penalty to the original manipulability measure, which simply evaluates the volume of the ellipsoid, depending on how much the ellipsoid is offset. Numerical examples by using a simple two-fingered robot hand are shown to demonstrate the effectiveness of the proposed measure.

Manipulability is a measure of performance for mechanical manipulators. Intuitively, Manipulability at a point of a manipulator workspace measures how easy is to reach the neighbour points. Currently, this value is obtained using an algebraic formula based on the Jacobian of the manipulator that is not very intuitive. Also, this formulation defines Manipulability as a continuous function of the workspace coordinates; however, due to natural restrictions for the mechanical implementation, actual devices include physical limits where this algebraic formulation produces incoherent Manipulability values. This work presents a new formulation based on fuzzy rules that provides a more intuitive definition of Manipulability. This formulation solves the boundary problem, while remains consistent with the algebraic one in those spatial zones where this works correctly. In order to demonstrate the advantage of this new approach, the Manipulability of a well known commercial haptic device has been studied comparing both formulations