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The objective of this work is to use the relational configuration schema to describe hand postures and to simulate the posture-evolution. First, a general scheme of vocabulary for describing relational configurations is developed. Translating the conventional way of describing relationships using this scheme it is found that it is possible to evolve a structured way of picking description elements from the vocabulary which is amenable to computer implementation. This is demonstrated through a contact based description of hand posture and determination of the respective hand configuration through an optimization based inverse kinematics formulation. In the second part, grasp-evolution is simulated. A linear interpolation and Bezier interpolation between two specified Mudras or hand postures have been studied. Intermediate Mudras necessary for specification of the control polygon of the Bezier is obtained from traversal of the Mudra hierarchy studied earlier.

This paper presents a geometric method for estimating the filed-of-view (FoV) for monocular and binocular vision using a 3D scanned human face. The traditional vision-cone approach offers simplicity but may lead to spurious inferences during ergonomic evaluations involving peripheral vision. FoV is asymmetric due to unrestricted zygomatic vision and restrictions on nasal side. Thus its accurate modeling is important for effective simulation of visual performance. Given a tessellated face model and the location of the pupil, the present work computes the FoV edges on the face with respect to the pupil. The algorithm is divided in two steps, visible triangle computation and silhouette edge detection for FoV estimation. A qualitative comparison of samples with the standard perimetry data and right circular cones used in DHM shows that the FoV is very similar to the physiological visual-field maps and the cones used in DHM are conservative.

The primary objective of the paper is to make use of statistical digital human model to better understand the nature of reach probability of points in the taskspace. The concept of task dependent boundary-manikin is introduced to geometrically characterize the extreme individuals in the given population who would accomplish the task. For a given point of interest and task, the map of the acceptable variation in anthropometric parameters is superimposed with the distribution of the same parameters in the given population to identify the extreme individuals. To illustrate the concept, the task space mapping is done for the reach probability of human arms. Unlike the boundary manikins, who are completely defined by the population, the dimensions of these manikins will vary with task, say, a point to be reached, as in the present case. Hence they are referred to here as the task dependent boundary manikins.

This paper presents a novel method of representing rotation and its application to representing the ranges of motion of coupled joints in the human body, using planar maps. The present work focuses on the viability of this representation for situations that relied on maps on a unit sphere. Maps on a unit sphere have been used in diverse applications such as Gauss map, visibility maps, axis-angle and Euler-angle representations of rotation etc. Computations on a spherical surface are difficult and computationally expensive; all the above applications suffer from problems associated with singularities at the poles. There are methods to represent the ranges of motion of such joints using two-dimensional spherical polygons. The present work proposes to use multiple planar domain “cube” instead of a single spherical domain, to achieve the above objective. The parameterization on the planar domains is easy to obtain and convert to spherical coordinates.

The objective of this work is to develop a systematic methodology for describing hand postures and grasps which is independent of the kinematics and geometry of the hand model which in turn can be used for developing a universal referencing scheme. It is therefore necessary that the scheme be general enough to describe the continuum of hand poses. Indian traditional classical dance form, “Bharathanatyam”, uses 28 single handed gestures, called “mudras”. A Mudra can be perceived as a hand posture with a specific pattern of finger configurations. Using modifiers, complex mudras could be constructed from relatively simple mudras. An adjacency matrix is constructed to describe the relationship among mudras. Various mudra transitions can be obtained from the graph associated with this matrix. Using this matrix, a hierarchy of the mudras is formed.

In this paper the influence of dimensional variability of the arm on the reach in a given operational space is studied. The arm is modeled as a two-linked planar manipulator using the upper and lower arm dimensions from a public domain anthropometric database. The probability of reach for different points is determined assuming independent distribution, dependent distribution, constant proportion and identical percentiles for the two links in the dyad. The computed probability distribution is then used to understand the implication of these assumptions on the interpretation of reachability of points in the operational space by the given population. Results from the dependent distribution are found to be closest to those obtained from raw data. The quality of reach within the workspace is studied using average condition number corresponding to the reach configuration of different individuals at different points in the workspace.