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In Sections III-VI, admittance selection conditions for four typical two-PC states each in single-point contact were presented. The strategies and procedures can be used for any combination of two single-contact PCs. In general, for each PC, translational variables δ ij are chosen based on the PC's type. Using translational variables δ ij and orientational variables (u, θ), the contact wrenches w i and errormeasure vector d are obtained and the interaction of the wrenches from the two PCs is addressed in the calculation of their magnitudes. Then, by (5), the error-reduction function is expressed in terms of (δ ij , u, θ). The function obtained is a polynomial in (δ ij , sin θ) with coefficients being functions of u and the admittance A. Based on the nature of the contact and the properties of the error-reduction function, selection conditions for the admittance are obtained.Sections III-VI present results for four of the six combinations of two single-point contact PCs. The remaining two combinations are similar. Note that both the wrench associated with {e − e} contact (34) and the wrench associated with {{v − f } contact (22) contain only the linear term in sin θ.The admittance selection conditions are obtained by geometric and force analysis of each contact state. Redundant coordinates δ ij are used to describe the translational variation. These coordinates are treated as independent variables in a large range (without considering the constraints due to contact). Thus, the conditions obtained are conservative. To make the conditions less conservative, the range of configuration variables considered can be decomposed into a number of nonoverlapping subranges, each addressed with equivalent conditions.In this paper, a single admittance control law (1) is considered for each contact state. The sufficient conditions obtained impose conditions on the admittance to ensure error reducing motion for the entire contact state. Due to uncertainty in identifying which contact state actually occurs, a single admittance control law (1) could be used for all contact cases, if the conditions for all contact states were satisfied simultaneously.In practice, the selection of an appropriate admittance A can be formulated as a search routine to find an admittance matrix A subject to the appropriate conditions. For instance, an optimization procedure can be used to find an admittance matrix for which sufficient conditions such as those described in the paper are used as "constraints." An example illustrating the application of error-reduction conditions to obtain a desired admittance was presented in [5] for a planar case. This procedure applies to the spatial cases as well.In summary, we have presented conditions for admittance selection of a polyhedral rigid body for force-guided assembly in cases having two point contact PCs. We have shown that, for these cases, the admittance control law can be selected based on its behavior at a finite number of configurations. If the error-reduction conditions are satisfied at these configur...

The process of trying to understand users' perspectives and their mental model is inherently challenging, as anyone who has been involved in conducting field studies and interviewing users can attest to. At the heart of this process is the need to create trust between the interviewer and the interviewee in order to build bonds which facilitate richer information exchange. Building apprenticeship relations is one approach which sees the interviewee as teacher and the interviewer as student/apprentice. However establishing these relations, particularity within a short time frame and within an industrial domain, can be difficult. This paper therefore addresses some of the challenges associated with building these relationships and how researchers can strengthen their connection with the users they interact with.

A distinct property of robot vision systems is that they are embodied. Visual information is extracted for the purpose of moving in and interacting with the environment. Thus, different types of perception-action cycles need to be implemented and evaluated.In this paper, we study the problem of designing a vision system for the purpose of object grasping in everyday environments. This vision system is firstly targeted at the interaction with the world through recognition and grasping of objects and secondly at being an interface for the reasoning and planning module to the real world. The latter provides the vision system with a certain task that drives it and defines a specific context, i.e. search for or identify a certain object and analyze it for potential later manipulation. We deal with cases of: (i) known objects, (ii) objects similar to already known objects, and (iii) unknown objects. The perception-action cycle is connected to the reasoning system based on the idea of affordances. All three cases are also related to the state of the art and the terminology in the neuroscientific area.

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