Saccade and smooth pursuit are two important functions of human eye. In order to enable bionic eye to imitate the two functions, a control method that implements saccade and smooth pursuit based on the three-dimension...Saccade and smooth pursuit are two important functions of human eye. In order to enable bionic eye to imitate the two functions, a control method that implements saccade and smooth pursuit based on the three-dimensional coordinates of target is proposed. An optimal observation position is defined for bionic eye based on three-dimensional coordinates. A kind of motion planning method with high accuracy is developed. The motion parameters of stepper motor consisting of angle acceleration and turning time are computed according to the position deviation, the target＇s angular velocity and the stepper motor＇s current angular velocity in motion planning. The motors are controlled with the motion parameters moving to given position with desired angular velocity in schedule time. The experimental results show that the bionic eye can move to optimal observation positions in 0.6 s from initial location and the accuracy of 3D coordinates is improved. In addition, the bionic eye can track a target within the error of less than 20 pixels based on three-dimensional coordinates. It is verified that saccade and smooth pursuit of bionic eye based on three-dimensional coordinates are feasible.展开更多
During pursuit eye movements, whether the relationships among the visual sensitivity, pursuit velocity, and target velocity are linear or non-linear is an old issue. In this study, we reexamined their relationships wi...During pursuit eye movements, whether the relationships among the visual sensitivity, pursuit velocity, and target velocity are linear or non-linear is an old issue. In this study, we reexamined their relationships with seven speeds by a simple character discrimination task using an infrared eye tracker. Our results found that the pursuit velocity and accuracy were non-linearly related with the target velocity. Besides, the perceptual sensitivity was not linearly related with the pursuit velocity either. A significant difference existed between lower （less than 20 deg/s） and higher speeds （greater than 20 deg/s）. In addition, we found there was no position bias of visual sensitivity between ahead of and behind the pursuit target, but there was a significant perceptual dissymmetry between horizontal and vertical directions at lower pursuit speeds.展开更多
Previous studies have demonstrated that advanced Alzheimer＇s disease（AD）patients have deficiency of eye movements.However,there have been no reports on eye movement in the early stages of AD.The aim of this study w...Previous studies have demonstrated that advanced Alzheimer＇s disease（AD）patients have deficiency of eye movements.However,there have been no reports on eye movement in the early stages of AD.The aim of this study was to evaluate pursuit ocular movements（POM）provided by a vision-based non-intrusive eye tracker in patients with early AD.POM values were significantly lower in AD patients than in normal controls（P 〈 0.01）.In AD patients,POM values were not closely correlated with the Mini-Mental State Examination scores（P = 0.3）.There was no significant difference in POM values among patients treated with or without anticholinesterase therapy.We used a vision-based method,for non-intrusive eye tracking,which can be proposed as a possible tool for supporting the diagnosis of early AD.展开更多
基金This study was supported by the National Natural Science Foundation of China under Grant No. 61573347 and in part by the National High Technology Research and Development Program of China （＂863 Program＂） under Grant No. 2015AA042307 and the special fund of Jiangsu Province for the transformation of scientific and technological achievements under Grant BA2015144.
文摘Saccade and smooth pursuit are two important functions of human eye. In order to enable bionic eye to imitate the two functions, a control method that implements saccade and smooth pursuit based on the three-dimensional coordinates of target is proposed. An optimal observation position is defined for bionic eye based on three-dimensional coordinates. A kind of motion planning method with high accuracy is developed. The motion parameters of stepper motor consisting of angle acceleration and turning time are computed according to the position deviation, the target＇s angular velocity and the stepper motor＇s current angular velocity in motion planning. The motors are controlled with the motion parameters moving to given position with desired angular velocity in schedule time. The experimental results show that the bionic eye can move to optimal observation positions in 0.6 s from initial location and the accuracy of 3D coordinates is improved. In addition, the bionic eye can track a target within the error of less than 20 pixels based on three-dimensional coordinates. It is verified that saccade and smooth pursuit of bionic eye based on three-dimensional coordinates are feasible.
基金supported by the National Natural Science Foundation of China under Grant No.60972108,91120013,61375115,31300912973 Project under Grant No.2013CB329401+1 种基金Key Technology Research&Development Programs of Sichuan Province under Grant No.2011GZ0073the Fundamental Research Funds for the Central Universities under Grant No.ZYGX2013J098,ZYGX2011X017
文摘During pursuit eye movements, whether the relationships among the visual sensitivity, pursuit velocity, and target velocity are linear or non-linear is an old issue. In this study, we reexamined their relationships with seven speeds by a simple character discrimination task using an infrared eye tracker. Our results found that the pursuit velocity and accuracy were non-linearly related with the target velocity. Besides, the perceptual sensitivity was not linearly related with the pursuit velocity either. A significant difference existed between lower （less than 20 deg/s） and higher speeds （greater than 20 deg/s）. In addition, we found there was no position bias of visual sensitivity between ahead of and behind the pursuit target, but there was a significant perceptual dissymmetry between horizontal and vertical directions at lower pursuit speeds.
文摘Previous studies have demonstrated that advanced Alzheimer＇s disease（AD）patients have deficiency of eye movements.However,there have been no reports on eye movement in the early stages of AD.The aim of this study was to evaluate pursuit ocular movements（POM）provided by a vision-based non-intrusive eye tracker in patients with early AD.POM values were significantly lower in AD patients than in normal controls（P 〈 0.01）.In AD patients,POM values were not closely correlated with the Mini-Mental State Examination scores（P = 0.3）.There was no significant difference in POM values among patients treated with or without anticholinesterase therapy.We used a vision-based method,for non-intrusive eye tracking,which can be proposed as a possible tool for supporting the diagnosis of early AD.
