Transformation of vestibular signals for the decisions of hand choice during whole body motion

In daily life, we frequently reach toward objects while our body is in motion. We have recently shown that body accelerations influence the decision of which hand to use for the reach, possibly by modulating the body-centered computations of the expected reach costs. However, head orientation relative to the body was not manipulated, and hence it remains unclear whether vestibular signals contribute in their head-based sensory frame or in a transformed body-centered reference frame to these cost calculations. To test this, subjects performed a preferential reaching task to targets at various directions while they were sinusoidally translated along the lateral body axis, with their head either aligned with the body (straight ahead) or rotated 18° to the left. As a measure of hand preference, we determined the target direction that resulted in equiprobable right/left-hand choices. Results show that head orientation affects this balanced target angle when the body is stationary but does not further modulate hand preference when the body is in motion. Furthermore, reaction and movement times were larger for reaches to the balanced target angle, resembling a competitive selection process, and were modulated by head orientation when the body was stationary. During body translation, reaction and movement times depended on the phase of the motion, but this phase-dependent modulation had no interaction with head orientation. We conclude that the brain transforms vestibular signals to body-centered coordinates at the early stage of reach planning, when the decision of hand choice is computed. NEW & NOTEWORTHY The brain takes inertial acceleration into account in computing the anticipated biomechanical costs that guide hand selection during whole body motion. Whereas these costs are defined in a body-centered, muscle-based reference frame, the otoliths detect the inertial acceleration in head-centered coordinates. By systematically manipulating head position relative to the body, we show that the brain transforms otolith signals into body-centered coordinates at an early stage of reach planning, i.e., before the decision of hand choice is computed.

Analysis and Simulation of Mineral Grading Sieve Mechanism Motion Based on ADAMS

This paper introduces a kind of screening machinery that applied to mineral grading.It needs to simplify its structure for expedient simulation and build the three-dimensional solid model of the screen frame in the SolidEdge circumstance, and then be imported into ADAMS software to improve and perfect the model and conduct the analysis and simulation. Ultimately the curves of motion and changes of pressure angle were obtained. The approximate formula of the screen frames acceleration can be obtained to find out the inertial acceleration of the mineral particles by analyzing and simulating its kinematics, which supplys the basis of Stress analysis of mineral particles on the sifter. It provides a theory to optimize screening machinery by analyzing the changes of pressure angle.

Dynamic Characteristic of MEMS Inertial Device by Simulation

Inertial device is an important part of the fuze system. It is a key mechanism to keep safety at ordinary times and period after launch. Therefore, the dynamic characteristics of the inertial device during falling or launching environments are very important. The paper make a study of the dynamic characteristics of the MEMS inertial device used in the fuze of the ammunition under the two kind of inertial acceleration by simulation. The simulation result shows that the MEMS inertial device can ensure the safety of fuze and ammunition.