Head-Controlled Goal-Directed Movement Under Dynamic Virtual Environment

With the development of virtual reality and augmented reality,traditional interaction ways fail to match the increasing needs for multiple interaction technology.Apart from the well-researched eye-tracking technology and multimodal interaction ways,head rotation is also a promising interaction technology and is the topic of this research.Concerning the details of this research,on the one hand,virtual environments are more complicated than 2D interfaces and are often dynamical.On the other hand,moving/transforming is the most frequently used interaction task.Thus,this paper focuses on the head-controlled goal-directed movements under dynamic virtual environments.Using the idea of Woodworth's two-component model and research methods of Fitts' law related studies,we aim to explore the influence factors of the head-controlled goal-directed movements and its speed-accuracy tradeoff.In experiment 1,participants were asked to put a small sphere into a target sphere wearing head-mounted virtual reality helmet.The small sphere and target sphere was located at the depth of 3m and moving towards or away from the small sphere at the speed of 3m/s.This experiment aimed to explore the influence of movement amplitude,target tolerance,the size of small sphere and the initial moving direction of small sphere on the error rate and movement time of the moving task.Experiment 2 selected the two critical influencing factors of movement amplitude and target tolerance as independent parameters based on the result of experiment 1,adding the speed of target sphere as a third independent parameter.The rest is same as experiment 1.Main results of the research includes:(1)Similar to those results of stable goal-directed movements,movement amplitude and target tolerance are two vital factors;the speed of the target also has significant influence on goal-directed movements.(2)The moving-towards and movingaway situations have significant difference on error rate,movement time and peak speed and thus should be studied separately.(3)Under the moving-away situation,the whole moving process can be parsed into two phases of ballistic phase and correction phase based on the velocity-time profile.The ballistic phase is mainly affected by movement amplitude and the speed of target sphere while the correction phase is mainly affected by target tolerance and the speed of target sphere.No such separation exists for the moving-towards situation.(4)For both the moving-away and moving-towards situation,larger speed of target sphere leads to a wider distribution of small sphere,in the form of larger standard deviation and larger effective target width/tolerance.This research offers some hints on the usage of human space perception,action perception and vision while performing goal-directed movements via head rotation under dynamic virtual environments and lays a foundation for the design and application of relevant facilities.