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Contrast thresholds for sine-wave gratings of spatial frequencies of 2, 4, 12, and 16 cycles per degree were determined for normal and disabled readers at a range of stimulus durations. Normal readers demonstrated monotonically decreasing sensitivity with increasing spatial frequency at exposure durations between 40 and 100 milliseconds. At exposure(More)
Contrast sensitivity functions for normal and specifically disabled readers were measured in two experiments. Each study showed that specifically disabled readers and controls differ in the pattern of relative sensitivity across spatial frequencies. Both studies provide evidence of differences between normal and disabled readers on measures of visual(More)
This article investigates the problem of manipula-tor design for increased dynamic performance. Optimization techniques are used to determine the design parameters which improve manipulator performance. The dynamic performance of a manipulator is characterized by the inertial and acceleration properties of the end-eeector. Our study of inertial and(More)
The visual persistence of sinusoidal gratings of varying spatial frequency and contrast was measured. It was found that the persistence of low-contrast gratings was longer than that of high-contrast stimuli for all spatial frequencies investigated. At higher contrast levels of 1 and 4 cycles deg-1 gratings, a tendency for persistence to be independent of(More)
—Dynamic capability equations (DCE) provide a new description of robot acceleration and force capabilities. These refer to a manipulator's ability to accelerate its end-effector and to apply forces to the environment at the end-effector. The key features in the development of these equations are that they combine the analysis of end-effector accelerations,(More)
This article investigates the problem of redundant ma-nipulator design for optimal dynamic performance; speciically design of macro/mini structures. The dynamic performance of a manipulator is characterized by the inertial and acceleration properties of the end-eeector. However, for redundant manipulators the characteristics of motions in the end eeector(More)
The study of acceleration capability is concerned with the responsiveness of a manipulator to controller commands. In this paper we present a general model for the analysis of end-eeector linear and angular accelerations that accounts for the velocity eeects. The separate treatment of linear and angular motion directly addresses the inhomogeneities of(More)