The Role of Visual Feedback and Age When Grasping,Transferring and Passing Objects in Virtual Environments

ABSTRACT

Visual feedback about one’s own movements can be important for effective performance in natural and computer-generated environments. Previous work suggested that, for young adults, performance in virtual environments was influenced by the presence of a crude representation of the hand in a task-specific fashion. The current study was performed to determine whether this pattern of results holds across the lifespan. Specifically, we were interested in determining whether a representation of the hand is useful for movement performance in children, middle adults, and older adults when they reach to grasp an object, transfer it between their two hands, or receive it from a partner. Surprisingly, visual feedback condition had very little effect on performance in the current experiment, with the exception that participants in all three age groups altered how wide they opened their hand when grasping depending on visual condition. Patterns of reach and grasp performance changed across task depending on age, with older adults displaying different patterns than children and middle-aged adults. These results suggest that feedforward planning and the use of feedback are modulated by both age and task.     

An experimental study on the role of graphical information about hand movement when interacting with objects in virtual reality environments

In this series of experiments, we investigated whether a crude representation of the hand that was extinguished at movement onset improved performance when compared to a no-feedback situation. Subjects performed simple reach to grasp movements in a virtual environment in two experiments. In Experiment 1, trials were blocked so that subjects were aware that a graphical representation of the hand would either be available throughout the movement (FA), be removed at movement onset (FAB), or not be available (NF). In Experiment 2, trials were randomized so that subjects were unaware of whether feedback would be available throughout the trial or removed at movement onset. Our results indicated that when subjects were aware of the availability of graphical feedback, the FAB condition improved performance compared to the NF condition. Furthermore, movement time was similar in the two feedback available conditions (FA, FAB). In contrast, for the randomized trial presentation, the positive influence of the FAB condition was diminished. These results suggest that visual feedback available prior to movement onset can be used to calibrate the proprioceptive system and improve performance over a no feedback situation. These results can be applied by designers of virtual environments to solve problems related to occlusion of important environmental information by the hand as users reach to grasp and manipulate objects.     

Assessing design features of virtual keyboards for text entry

OBJECTIVE: The present research examined design of a virtual keyboard for text entry with a rotary controller, emphasizing users who differ in age and system experience. BACKGROUND: Existing research has minimally addressed usage frequency, age, and the effects of display shape and letter arrangement on movement and visual search components of text entry tasks. The present research was conducted to close these gaps. METHOD: Two experiments were completed to examine younger (18-28 years) and older (60-75 years) adults' movement and visual search capabilities using four keyboard shapes and three keyboard arrangements. In a third experiment examining combined effects on shape design, 32 younger (18-28 years) and 32 older (60-75 years) adults entered words on the two best shapes from the first experiments. RESULTS: For the movement task, movement time was lowest for shapes with higher shape-controller compatibility. For the visual search task, search time and accuracy were best on the alphabetic arrangement. In the combined task, shape did not significantly influence performance at different levels of practice. Transfers, however, suggested that the shape with salient visual features elicited a text entry strategy for older adults that may promote more consistent performance under occasional usage. CONCLUSION: The studies together demonstrate that keyboard shape is important for efficient performance. Shape-controller compatibility facilitated performance in both age groups. Salient features facilitate performance, especially for older adults. In nearly all cases alphabetic arrangement yielded the best performance. APPLICATION: Recommendations are provided for virtual keyboard design for different usage frequencies, contexts, and users.     

Helping older pedestrians navigate in the city: comparisons of visual,auditory and haptic guidance instructions in a virtual environment

Preserving older pedestrians’ navigation skills in urban environments is a challenge for maintaining their quality of life. However, existing aids do not take into account older people’s perceptual and cognitive declines nor their user experience, and they call upon sensory modalities that are already used during walking. The present study was aimed at comparing different guidance instructions using visual, auditory, and haptic feedback in order to identify the most efficient and best accepted one(s). Sixteen middle-age (non-retired) adults, 21 younger-old (young-retired) adults, and 21 older-old (old-retired) adults performed a navigation task in a virtual environment. The task was performed with visual feedback (directional arrows superimposed on the visual scenes), auditory feedback (sounds in the left/right ear), haptic feedback (vibrotactile information delivered by a wristband), combinations of different types of sensory feedback, or a paper map. The results showed that older people benefited from the sensory guidance instructions, as compared to the paper map. Visual and auditory feedbacks were associated with better performance and user experience than haptic feedback or the paper map, and the benefits were the greatest among the older-old participants, even though the paper-map familiarity was appreciated. Several recommendations for designing pedestrian navigation aids are proposed.     

A hybrid haptic guidance model for tank gunners in high precision and high speed motor skill training

Haptic-based paradigms for human motor skill training which include virtual fixture, record-play method, shared control scheme and haptic disturbance have been proposed and widely used for applications like surgery, assembly, rehabilitation, motor skill and so on. However, no haptic-based training scheme applies to all types of human motor skills that new ideas and new approaches should be explored for some special training tasks. For example, tank gunners have to be rigorously trained to be able to complete the most accurate manipulation in the shortest possible time. Accuracy and operating speed are both critical for them to grasp the skill; therefore, tank gunnery is defined as a type of high precision and high speed human motor skill. In this paper, a hybrid spring-damper model which fuses haptic fixture and record-play is presented to simultaneously train accuracy and operating speed. The training approach is suitable for novices at all levels since force feedback is decomposed into two components: one for training accuracy, the other for training speed. The virtual envelope depicting is chosen as the training task for novices to validate the effectiveness of the proposed haptic-based scheme in high precision and high speed skill training. Experimental results indicate that force feedback generated based on the hybrid model can benefit novices in fast improving performances on tank gunnery.     

Virtual surfaces and the influence of cues to surface shape on grasp

This research compared grasps to real surfaces with grasps to virtual surfaces, and used virtual surfaces to examine the role of cues to surface shape in grasp. The first experiment investigated the kinematics of overhand grasps to real and virtual objects. The results showed that, compared with grasps to real surfaces, grasps to virtual objects were different in the deceleration phase of the grasp movement and were more variable in their endpoint position. The second experiment used several measures to examine the relationship between the visual perception of a surface and the decision to grasp the surface with either an over-or underhand grasp. It was found that visual perception of the surface was consistent with the grasping decision. The third experiment used virtual surfaces to examine how the removal of visual cues to shape affected the decision to switch from over- to underhand grasp. Results showed that the orientation at which the decision switched was dependent on the visual information content. Overall, the results showed that subtle differences existed between the reach to grasp movements towards real and virtual surfaces and that the decision to choose between grasp types was dependent on the visual information used to depict the virtual surface. These results are discussed in relation to the design and use of input devices to enable manipulation of three-dimensional objects in virtual worlds.     

Vision for Performance in Virtual Environments: The Role of Feedback Timing

This work explores how people use visual feedback when performing simple reach-to-grasp movements in a tabletop virtual environment. In particular we investigated whether visual feedback is required for the entire reach or whether minimal feedback can be effectively used. Twelve participants performed reach-to-grasp movements toward targets at two locations. Visual feedback about the index finger and thumb was provided in four conditions: vision available throughout the movement, vision available up to peak wrist velocity, vision available until movement initiation, or vision absent throughout the movement. It was hypothesized that vision available until movement onset would be an advantage over a no vision situation yet not attain the performance observed when vision was available up to peak velocity. Results indicated that movement time was longest in the no vision condition but similar for the three conditions where vision was available. However, deceleration time and peak aperture measures suggest grasping is more difficult when vision is not available for at least the first third of the movement. These results suggest that designers of virtual environments can manipulate the availability of visual feedback of one's hand without compromising interactivity. This may be applied, for example, when detailed rendering of other aspects of the environmental layout is more important, when motion lag is a problem or when hand/object concealment is an issue.     

Type of visual feedback during practice influences the precision of the acquired internal model of a complex visuo-motor transformation

This study investigated the influence of the type of visual feedback during practice with a complex visuo-motor transformation of a sliding two-sided lever on the acquisition of an internal model of the transformation. Three groups of participants, who practised with different types of visual feedback, were compared with regard to movement accuracy, curvature and movement time. One group had continuous visual feedback during practice and two groups were presented terminal visual feedback, either only the end position of the movement or the end position together with the trajectory of the cursor. Results showed that continuous visual feedback led to more precise movement end positions during practice than terminal visual feedback, but to less precise movements during open-loop tests. This finding indicates that terminal visual feedback supports the development of a precise internal model of a new visuo-motor transformation. However, even terminal feedback of the cursor trajectory during practice did not result in an internal model, which includes appropriate curvatures of hand movements. STATEMENT OF RELEVANCE: This paper presents results on the influence of type of visual feedback on learning the complex motor skill of controlling a sliding lever. These findings contribute to the conceptual basis of optimised training procedures for the acquisition of sensori-motor skills required for the mastery of instruments utilised in minimally invasive surgery.     

The effect of age on the hand movement time during machine paced assembly tasks for female workers

The share of older adults in the workforce is increasing in many countries. In the manufacturing industry a high proportion of assembly tasks are machine paced. Previous studies have shown that older adults tend to have longer movement times than younger adults when working at a self-selected pace. However, it is unclear whether older adults can obtain the same hand movement time as a younger group when performing machine paced work at the assembly line. In the current study, 10 older and 10 younger female participants performed simulated light-duty assembly tasks during which the hand movement times were recorded. The results showed that the older participants were capable of working at the set pace and there was no significant difference between age groups in hand movement times (989.9 msec vs. 986.6 msec, p = 0.5647). A likely explanation to the results is that the older participant had to work closer to their physical limits or capacity in order to compensate for the age effect on movement time.     

基于虚拟桌面的自主学习系统研究

为了提高自主学习质量,文章针对云计算和自主学习的特点设计基于虚拟桌面的自主学习系统。基于虚拟桌面的自主学习模式通过即时反馈功能,提出学习建议和操作示范,在交互学习环境中,不断提供并优化技能学习支持服务,较好的解决了学习过程中时间不连续性及环境变化的影响,较好的满足了学生的需求,并有效提高了学生的专业技能。     

面向人机工程学测试的虚拟手仿真模型

以人机工程学测试为目标提出虚拟手仿真模型,建立虚拟手运动学模型。提出一种曲线拟合的校准方法,以获取精确的数据,更好地控制虚拟手的运动。建立弹簧模型计算手与被抓取物体之间的受力,以视觉渲染的形式将其反馈给用户。实验结果表明,虚拟手可自然地抓取三维虚拟物体,视觉反馈的使用可免于购买昂贵的力反馈设备。     

The effects of multimodal feedback on older adults' task performance given varying levels of computer experience

This experiment examines the effect that computer experience and various combinations of feedback (auditory, haptic, and/or visual) have on the performance of older adults completing a drag-and-drop task on a computer. Participants were divided into three computer experience groups, based on their frequency of use and breadth of computer knowledge. Each participant completed a series of drag-and-drop tasks under each of seven feedback conditions (three unimodal, three bimodal, one trimodal). Performance was assessed using measures of efficiency and accuracy. Experienced users responded well to all multimodal feedback while users without experience responded well to auditory-haptic bimodal, but poorly to haptic-visual bimodal feedback. Based on performance benefits for older adults seen in this experiment, future research should extend investigations to effectively integrate multimodal feedback into GUI interfaces in order to improve usability for this growing and diverse user group.     

Virtual reality software package for implementing motor learning and rehabilitation experiments

Virtual reality games for rehabilitation are attracting increasing growth. In particular, there is a demand for games that allow therapists to identify an individual’s difficulties and customize the control of variables, such as speed, size, distance, as well as visual and auditory feedback. This study presents and describes a virtual reality software package (Bridge Games) to promote rehabilitation of individuals living with disabilities and highlights preliminary researches of its use for implementing motor learning and rehabilitation. First, the study presents seven games in the software package that can be chosen by the rehabilitation team, considering the patient’s needs. All game characteristics are described including name, function presentation, objective and valuable measurements for rehabilitation. Second, preliminary results illustrate some applications of two games, considering 343 people with various disabilities and health status. Based on the results, in the Coincident Timing game, there was a main effect of movement sensor type (in this instance the most functional device was the keyboard when compared with Kinect and touch screen) on average time reached by sample analyzed, F(2, 225) = 4.42, p < 0.05. Similarly, in the Challenge! game, a main effect was found for movement sensor type. However, in this case, touch screen provided better performance than Kinect and Leap Motion, F(2, 709) = 5.90, p < 0.01. Thus, Bridge Games is a possible software game to quantify motor learning. Moreover, the findings suggest that motor skills might be practiced differently depending on the environmental interface in which the game may be used.     

Development of a Weighted Heuristic for Website Evaluation for Older Adults

Older adults are the fastest growing population of Internet users. As websites acquire a greater number of older visitors, it is vital that they are designed with this demographic in mind. Older users typically have different user characteristics than younger users; they may have changes in perceptual abilities, motor skills, cognitive abilities, mental models, and confidence in the use of technology. This research documents the development of a new weighted heuristic measure for evaluating the usability of websites for older adults and its validation with performance testing. Results from a repeated measures analysis of variance indicated that websites with different heuristic classifications were significantly different with respect to performance metrics and System Usability Scale ratings. Conclusions point to the need for web design that takes into account preferences and abilities of older web users.     

Interaction techniques in desktop virtual environment: the study of visual feedback and precise manipulation method

Gesture-based systems allow users to interact with a virtual reality application in a natural way. Visual feedback for the gesture-based interaction technique has an impact on the performance and the hand instability making the manipulation of the object less precise. This paper investigated two new interaction techniques in a virtual environment. It describes the influence of natural and non-natural virtual feedback in the selection process using the GITDVR-G interaction technique, which consists of a grasping visual feedback. The GITDVR-G was evaluated in a virtual knee surgery training system. The results showed that it was effective in terms of the task completion time, and that the participants preferred the natural grasping visual feedback. Besides that, the precise manipulation in a newly-designed interaction technique (Precise GITDVR-G) was evaluated. The Precise GITDVR-G includes a normal manipulation mode and a precise manipulation mode that can be triggered by hand gestures. During the precise manipulation mode, an inset view will appear and move with the selected object to provide a better view to users, while the movements of the virtual hand are scaled down to improve the precision. Four different configurations of the precise manipulation technique were evaluated, and the results showed that the unimanual control method with an inset view performed better in terms of the task performance time and the subjective feedback. The finding suggested that the realistic virtual grasping visual feedback can be applied in a virtual hand interaction technique, and that the inset view feature is helpful in the precise manipulation.     

Learning disabilities and visual-motor skills; comparing assessment from a hapto-virtual reality tool and Bender-Gestalt test

Previous investigations conducted on post-secondary adult students with learning disabilities (LD) suggest that deficits in visual-motor skills contribute to difficulties in written expression which impact academic achievement. Intervention strategies for individuals with LD include assistive computer-based technologies (ATs) to compensate for or maximize performance. However, research fails to assess the impact of ATs on performance, learning, and motivation of students with LD. Also, one of the limitations of ATs is that they cannot be used for assessment and training and there are very few methods to assess or train visual-motor skills in this population. The present study explores the usefulness of a hapto-visual virtual reality motor skills assessment (MSA) device for visual-motor functioning in adults with and without LD. This is a preliminary step of developing an intervention to improve impaired visual-motor skills in adults with LD. A sample of 22 male and female university students with and without LD had their visual-motor skills pretested using a standard paper-and-pencil Bender-Gestalt (BG) test and were compared according to their performance on the MSA tool. We hypothesized that our LD participants’ performance would be significantly lower than our control participants on the VR task in terms of number of errors and speed. Results showed that participants without LD performed better and more rapidly on the VR task than participants with LD. There were no correlations between the BG and MSA performance. We did not find significant differences between the groups on the Bender-Gestalt scores, previous experience with video game, arousal, and mood. Our results suggest that a novel 3D virtual reality tool such as the MSA can potentially discriminate motor function of people with and without LD; however, the difference between both may also be due to a lack of problem-solving ability in LD.     

Older adults fail to see the periphery in a Web site task

Eye movement deficiencies are inherent with age and tend to increase in distracting visual fields, in the useful field of view (UFoV), and when information is located in the periphery. Despite well-known age-related differences in eye movement, there has been limited empirical study into how older adults look at Web sites. The study of eye movement during Web site interaction is advantageous to the study of UFoV theory because Web sites are typically complex, with important navigational elements located in the periphery. Using non-invasive eye tracking, eye movement patterns were investigated in young, middle, and older adults while they initially interacted with a typical Web site (i.e., standard top and left navigation). Older adults looked less frequently at peripheral parts of the screen compared to young adults, with the left and top navigation accounting for the greatest age-related differences. Age-related differences in eye movement emerged during the initial 10 s and were independent from Internet experience, suggesting differences in eye movement while interacting with Web sites are inherent with aging. Results show age-related differences in eye movement during a Web site task. These applied, experimental results directly support UFoV cognitive theory in a real-world setting.     

Research on auxiliary methods of swimming training virtual simulation technology based on embedded computer✰

Virtual Reality (VR) is a partnership between an independent hardware and software integrated system that ships it into a nearly simulated environment. Studies have shown that technology modifies variables related to an individual's visual and motor skills. Therefore, there are many possible explanations for the positive effects of encounters in sports that need to be considered using virtual reality. Virtual Reality Optimization Technique (VROT) can also trigger motor learning in the brain responsible for motor activity, thus using motor imaging (MI) technology, even when no action is occurring. This application is used to train swimming. This provides the criteria for evaluation, and the evaluated group will receive the experimental group. Swimming is one of the most popular games to train students and perform better results using the virtual reality technique. Solving the swimming lesson system is improving the ecological validity of the study, maintaining the great potential for cognitive and behavioral research, and separating cognitive behavior. Perform a comparative analysis of the student's correct and incorrect swimming practice. The proposed system analyzes the result using virtual reality technique based on the FPGA controller and getting better performance results.     

An investigation of handheld device use by older adults with age-related macular degeneration

This study investigates factors affecting handheld human - computer interaction (HCI) for older adults with Age-related Macular Degeneration (AMD). This is largely an uncharted territory, as empirical investigations of HCI concerning users with visual dysfunction and/or older adults have focused primarily on desktop computers. For this study, participants with AMD and visually healthy controls used a handheld computer to search, select and manipulate familiar playing card icons under varied icon set sizes, inter-icon spacing and auditory feedback conditions. While all participants demonstrated a high rate of task completion, linear regression revealed several relationships between task efficiency and the interface, user characteristics and ocular factors. Two ocular measures, severity of AMD and contrast sensitivity, were found to be highly predictive of efficiency. The outcomes of this work reveal that users with visual impairments can effectively interact with graphical user interfaces on small displays in the presence of low-cost, easily implemented design interventions. Furthermore, results demonstrate that the detrimental influence of AMD and contrast sensitivity on handheld technology interaction can be offset by such interventions. This study presents a rich data set and is intended to inspire future work characterizing and modeling the interactions of individuals with visual impairments with non-traditional information technology platforms and contexts.     

基于DSP的扫描平台电机控制系统

用于大尺寸测量定位的工作空间测量定位系统(WMPS)是多站光电扫描交汇测量系统的简称,优点在于多点实时测量与跟踪,测量精度高.平台旋转运动的稳定是保障测量系统高精度的首要因素.采用空间电压矢量调制(SVPWM)方式驱动电机,可有效地减小电机的转矩脉动和输出电压谐波.采用锁相环的反馈控制方法,配合电机上的光电码盘,可以实...