This paper introduces a novel robotic finger concept for variable impedance grasping in unstructured tasks. A brief literature survey reveals the need for minimal component designs and the benefits of impedance control schemes for interaction tasks such as grasping. The novel robotic finger concept supports these insights by combining three key features: minimal actuation, variable mechanical compliance and full manipulability. This combination of features allows for a minimal component design, while reducing control complexity and still providing required dexterity and grasping capabilities. The conceptual properties (such as variable compliance) are studied in a port-Hamiltonian framework. The framework proved to be suitable in analyzing and understanding the finger properties, which will be used for future controller design.

This paper presents a method to utilize a port-based multibody contact model for simulating dynamic interaction between irregular surfaces. The existing compliant contact model requires an analytic parametrization of the surfaces involved in the interaction, the definition of a Gauss frame in each of the contact points and initialization of the candidate contact points. The authors intend to apply this contact model for cases in which the surfaces of the 3D interacting bodies can not be described (easily) by a geometrically defined surface. Such surfaces are often represented by 3D point meshes. This implies that the surfaces of the bodies have to be reconstructed from 3D point meshes where initialization of the candidate contact points is not arbitrary. This paper proposes the reconstruction of such surfaces by means of polynomial interpolation. With the aim of having a computationally efficient simulator, the surface interpolation is restricted to small patches around the candidate contact points. To select these candidates, the proposed simulation approach is completed by using a fast (existing) collision detection algorithm. Simulation results are validating the effectiveness of the proposed modeling and simulation approach.

Safety is a critical success factor for consumer acceptance of domestic robotic products. Some researchers have adopted the head injury criterion (HIC) as absolute safety norm. However, this norm covers only part of the safety risk. In many cases skin damage (e.g. cuts, wounds, etc) can be a more serious risk. This article shows how to work towards a novel absolute safety measure for evaluating the shape and material choices of a robotic design w.r.t. skin damage. The proposed safety norm evaluates the situation of an unintended uncontrolled collision of a robotic part against a human. Maximum curvatures of the exterior robotic shape are approximated as a sphere in contact with the human skin (locally approximated as a flat surface). This local spheric approximation of the impact contact is used to predict maximum tensile stress during impact of the robotic part on the human. Robotic designs that include points for which the tensile strength of the skin is exceeded will cause at least skin fracture and are therefore considered intrinsically unsafe. While in general applicable, this paper specifically addresses how to apply the proposed norm in the case of safety evaluation of robotic manipulators.