Donald D. Nelson

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We present a method for painting texture maps directly onto trimmed NURBS models using a haptic interface. The haptic interface enables an artist to use a natural painting style while creating a texture. It avoids the traditional difficulty of mapping between the 2D texture space and the 3D model space by using parametric information available from our(More)
A haptic display system is presented for manipulating virtual mechanisms derived from a mechanical CAD design. Links are designed and assembled into mechanisms using Utah’s Alpha.1 CAD system, and are then manipulated with a Sarcos Dextrous Arm Master. Based on the mechanism’s kinematics and the virtual grasp, the motion of the master is divided into motion(More)
Previous work in haptics surface tracing for virtual prototyping and surface design applications has used a point model for virtual finger-surface interaction. We extend this tracing method for surface-to-surface interactions. A straightforward extension of the point-surface formulation to surface-surface can yield extraneous, undesirable solutions,(More)
Haptic rendering should not be limited to immobile polygonal models. This paper presents a system that performs Direct Parametric Tracing (DPT) on maneuverable Non-Uniform Rational B-Splines (NURBS) models without the use of an intermediate representation. The system distributes computation between an advanced CAD modeling system and a microprocessor(More)
Previous interactive works have used springs, heuristics, and dynamics for surface placement applications. We present an analytical technique for kilohertz rate manipulation of CAD models with virtual surface and trimming constraints. The optimization approach allows best placement and sensitivity analysis for mechanical design objectives and parametric(More)
Previous work in haptics surface tracing for virtual prototyping and surface design applications has used a point model for virtual finger-surface interaction. We extend this tracing method for surface-to-surface interactions. A straightforward extension of the point-surface formulation to surface-surface can yield extraneous, undesirable solutions,(More)
User manipulation of assembly models can provide insight during the early, formulative design stages into kinematic and dynamic characteristics of a mechanism. We present the advantages of kinematic representation of constraint equations in fully Cartesian coordinates, a departure from standard practice for interactive mechanical assembly at interactive(More)
A fast design variation technique for mechanical systems is presented. It is used to interactively optimize mechanical characteristics while “self-assembling” or satisfying large systems of mechanical constraints. The high speed method is central to providing inverse dynamics force feedback in haptics and control applications. Performance advantages with(More)