A Novel Two-Layer and Two-Loop Deployable Linkage With Accurate Vertical Straight-Line Motion

This paper presents a novel two-layer and two-loop spatial deployable linkage which can only accurately output vertical straight-line motion. First, the degree-of-freedom (DOF) of the linkage is analyzed based on structure decomposition and screw theory, and the characteristic of the straight-line motion of the linkage is verified by checking the output twist of the end platform. Then, the kinematic model of the mechanism is established based on the conditions of the straight-line motion and the single DOF. Finally, several potentially typical applications of the linkage are exhibited. The straight-line linkage has relatively simple joint layouts and kinematics model and can be used as a deployable unit to construct some special deployable mechanisms.

A Study on the Averaged Visual Evoked Potential as a Correlate of Experience

The averaged visual evoked potentials of 5 subjects were recorded during perception of a tachistoscopically presented stationary, vertical straight line. The subjects had been trained to experience movement of the stimulus, i.e., on each exposure of the straight line they experienced it as lengthening from the fixation area to full length and then shortening back to the fixation area. Subjects' frequencies of experience (duration of perception expressed in Hertz) were 2.4, 2.2, 2.4, 1.6, and 1.7, respectively. For 3 of the 5 subjects the averaged visual evoked potential contained an oscillation at a frequency similar to the subject's frequency of experience.

Duration of Experienced Expansion and Contraction of a Circle

The stimulus was a white outline circle which for 60 msec. was projected onto a screen 2 m. from S. The diameter of the circle was 10 cm. and the circle line was approximately 1.5 mm. wide. Fixating the center of the circle Ss reported experiencing the circle as expanding from the point of fixation to full size and then contracting to the point of fixation. Ss' experiences fell in two classes. The durations of Ss' experience of expansion-contraction were measured in msec. Ss also participated in experiments in which they fixated the nethermost point of a 17-cm. vertical straight line which was 2 mm. wide. Ss experienced the line as lengthening from the point of fixation to full length and then shortening to the point of fixation. For a given S the durations of the experienced expansion-contraction of the circle and the experienced lengthening-shortening of the straight line were the same.