This paper presents a feasible formulation of reachability test for sensor-based navigation. It directly incorporates the distance sensor information and tolerates the sensing and control errors. The concept of obstacle range is proposed, and the intersection between obstacle ranges is investigated based on geometrical reasoning. The necessary and sufficient condition for reachability is derived, along with a reachability test algorithm. Based on obstacle ranges, the algorithm requires no analytical expression of obstacle boundaries. It is computationally efficient and can be applied to sensor-based autonomous robotic systems.

This paper presents a cost-effective solution - screwnail indentation for disassembly. It is shown that the screwnail indentation can overcome the geometry uncertainties of used products. A disassembly tool, using the screwnail as the end effector, is introduced. The disassembly task is decomposed into screwnail indentation process, task execution process, and separating process. Based on a kinematically admissible velocity field, an upper-bound analysis is performed for the screwnail indentation process and validated with an experimental set-up. The results can be applied to flexible disassembly.

A general dynamic force distribution (DFD) algorithm for multifingered grasping is presented. Based on the convexity and cone property of contact constraints, the optimal internal force is defined. Determination of the contact force is divided into two phases: (1) determine the direction of the optimal internal force during grasp planning and (2) determine the manipulation force and compensation factor during task manipulation. The total computation cost consists of off-line numerical iterations and on-line analytical computations. Only the latter is related to the real-time control. The algorithm can directly deal with the nonlinear and/or coupled constraints and well overcome the temporal discontinuity.

Formulates the force distribution for soft multi-fingered hands as choosing a suitable internal force such that the total contact force satisfies the frictional constraints. As a first step, the direction of the optimal internal force is defined based on the grasp locations. Implementation of the algorithm is divided into two phases: (1) determine the direction of the internal force during grasp planning; (2) determine the magnitude of the internal force during task manipulation. The total computation cost consists of off-line numerical iterations and online analytical computations. Only the latter is related to the real-time control. An example shows that the proposed algorithm can efficiently deal with the soft frictional constraints and well overcome the temporal discontinuity.

This paper deals with the problem of the equivalence of internal and interaction forces in multifingered grasping. The dimensions of these two force spaces are analyzed. It is shown that the internal force space can be more generally expressed as the direct sum of the interaction and parallel force spaces. Under certain conditions, the parallel force space disappears and the internal and interaction force spaces become coincident. In this sense, the internal force can be equivalently characterized by the interaction force or pairs of equal and opposite collinear forces. The necessary and sufficient conditions for this equivalent characterization, which depends upon the number of contacts and the distribution of their locations, are derived. The algebraic structure of the parallel force spaces is given. Some illustrative examples are also presented.