Richard A. Volz

Estimating 3-D location parameters using dual number quaternions

This paper describes a new algorithm for estimating the position and orientation of objects. The problem is formulated as an optimization problem using dual number quaternious. The advantage of using this representation is that the method solves for the location estimate by minimizing a single cost function associated with the sum of the orientation and position errors and thus is expected to have a better performance on the estimation, both in accuracy and in speed. Several forms of sensory information can be used by the algorithm. That is, the measured data can be a combination of measured points on an object’s surfaces and measured unit direction vectors located on the object. Simulations have been carried out on a Compaq 386/20 computer and the SiIIIUkItiOU reSUltS are analyzed. 0 1991 Academic press, inc.

Recognizing Partially Occluded Parts

The problem of recognizing an object from a partially occluded boundary image is considered, and the concept of saliency of a boundary segment is introduced. Saliency measures the extent to which the boundary segment distinguishes the object to which it belongs from other objects which might be present. An algorithm is presented which optimally determines the saliency of boundary segments of one object with respect to those of a set of other objects. An efficient template matching algorithm using templates weighted by boundary segment saliency is then presented and employed to recognize partially occluded parts. The results of these experiments illustrate the effectiveness of the new technique.

Teleautonomous systems: projecting and coordinating intelligent action at a distance

The authors have coined the term teleautonomous to describe methods for producing intelligent action at a distance. Teleautomation goes beyond autonomous control in that it blends in human intelligence and action as appropriate. It goes beyond teleoperation in that it incorporates as much autonomy as is possible or reasonable. A novel approach for solving one of the fundamental problems facing teleautonomous systems is discussed in detail: the need to overcome time delays due to telemetry and signal propagation. Concepts called time and position clutches are introduced; these allow the time and position frames, respectively, between the local user control and the remote device being controlled to be desynchronized. The design and implementation of these mechanisms lead to substantial telemanipulation performance improvements, including the novel result of improvements even in the absence of time delays. The controls also yield a simple protocol for handoffs of the control of manipulation tasks between local operators and remote systems. >

Optimal algorithms for symmetry detection in two and three dimensions

Exact algorithms for detecting all rotational and involutional symmetries in point sets, polygons and polyhedra are described. The time complexities of the algorithms are shown to be θ (n) for polygons and θ (n logn) for two- and three-dimensional point sets. θ (n logn) time is also required for general polyhedra, but for polyhedra with connected, planar surface graphs θ (n) time can be achieved. All algorithms are optimal in time complexity, within constants.

Design of integrated manufacturing system control software

A coordinated multifaceted conceptual framework for the development of real-time control software for integrated manufacturing systems is described. This orderly, rational, and structured approach is based on a blending of modern software concepts and formal semantic models. Using a common distributed language environment and generic (i.e. reusable) software, the authors construct control software as an assemblage of components written in the common distributed language. The semantics of the assemblages are modeled formally.

Toward real-time performance benchmarks for Ada

Benchmarks are developed to measure the Ada notion of time, the Ada features believed important to real-time performance, and other time-related features that are not part of the language, but are part of the run-time system; these benchmarks are then applied to the language and run-time system, and the results evaluated.

Acquiring robust, force-based assembly skills from human demonstration

Robots have been used successfully in structured settings, where the environment is controlled; this research is inspired by the vision of robots moving beyond structured, controlled settings. The work focuses on the problem of teaching robots force-based assembly skills from human demonstration. To avoid position dependencies, force-based discrete states (contact formations) are used to describe qualitatively how contact is being made with the environment. Sensorimotor skills are modeled using a hybrid control model, which provides a mechanism for combining continuous low-level force control with higher-level discrete event control. A change in qualitative, discrete state constitutes an event and triggers a new control command to the robot, which moves the assembly toward a new contact formation. In this way, the skill execution is not dependent on absolute position but rather responds to changes in the force-based qualitative state. Experimental results are presented which validate the approach and show how skill acquisition can be accomplished even with an imperfect demonstration.

Automatic generation of gripping positions

The problem of automatically determining gripping positions for objects based upon geometrical knowledge of the object and its environment is addressed. Both the question of what constitutes a good grip and the efficiency of the computational algorithms are considered. Two new criteria for the stability of a grip are proposed: resilience to slippage, and twisting in the gripper due to external forces and torques. Resilience to slippage is expressed in terms of friction effects of the surfaces involved, the shape of the contact between the gripper and object, and the distance of the grip point from the center of mass of the object. Two new performance measures are introduced to reflect resilience to twisting. A general grip planning strategy is introduced that is both run-time efficient and robust.

Evaluation of a haptic mixed reality system for interactions with a virtual control panel

We present a haptic feedback technique that combines feedback from a portable force-feedback glove with feedback from direct contact with rigid passive objects. This approach is a haptic analogue of visual mixed reality, since it can be used to haptically combine real and virtual elements in a single display. We discuss device limitations that motivated this combined approach and summarize technological challenges encountered. We present three experiments to evaluate the approach for interactions with buttons and sliders on a virtual control panel. In our first experiment, this approach resulted in better task performance and better subjective ratings than the use of only a force-feedback glove. In our second experiment, visual feedback was degraded and the combined approach resulted in better performance than the glove-only approach and in better ratings of slider interactions than both glove-only and passive-only approaches. A third experiment allowed subjective comparison of approaches and provided additional evidence that the combined approach provides the best experience.

A theoretical framework on proactive information exchange in agent teamwork

Proactive information delivery is critical to achieving effective teamwork. However, existing theories do not adequately address proactive information delivery. This paper presents a formal framework for proactive information delivery in agent teamwork. First, the concept of information need is introduced. Second, a new modal operator, InfoNeed is used to represent information needs. The properties of the InfoNeed operator and its relationships to other mental modal operators are examined, four types of information needs are formally identified, and axioms for anticipating the information needs of other agents are proposed and justified. Third, the axiom characterizing chains of helpful behavior in large agent teams is given. Fourth, the semantics for two proactive communicative acts (ProInform and 3PTSubscribe) is given using a reformulation of the Cohen-Levesque semantics for communicative acts in terms of the SharedPlans formalism of Grosz and Kraus. The work in this paper not only provides a better understanding of the underlying assumptions required to justify proactive information delivery behavior, but also provides a coherent basis for the specification and design of agent teams with proactive information delivery capabilities.