Assisting Visually Impaired People to Acquire Targets on a Large Wall-Mounted Display

Large displays have become ubiquitous in our everyday lives, but these displays are designed for sighted people.This paper addresses the need for visually impaired people to access targets on large wall-mounted displays. We developed an assistive interface which exploits mid-air gesture input and haptic feedback, and examined its potential for pointing and steering tasks in human computer interaction（HCI）. In two experiments, blind and blindfolded users performed target acquisition tasks using mid-air gestures and two different kinds of feedback（i.e., haptic feedback and audio feedback）. Our results show that participants perform faster in Fitts＇ law pointing tasks using the haptic feedback interface rather than the audio feedback interface. Furthermore, a regression analysis between movement time（MT） and the index of difficulty（ID）demonstrates that the Fitts＇ law model and the steering law model are both effective for the evaluation of assistive interfaces for the blind. Our work and findings will serve as an initial step to assist visually impaired people to easily access required information on large public displays using haptic interfaces.     

A user study of auditory versus visual interfaces for use while driving

This paper describes a user study on interaction with a mobile device installed in a driving simulator. Two new auditory interfaces were proposed and their effectiveness and efficiency were compared to a standard visual interface. Both auditory interfaces consisted of spatialized auditory cues representing individual items in the hierarchical structure of the menu. In the first auditory interface all items of the current level of the menu were played simultaneously. In the second auditory interface only one item was played at a time. The visual interface was shown on a small in-vehicle LCD screen on the dashboard. In all three cases, a custom-made interaction device (a scrolling wheel and two buttons) attached to the steering wheel was used for controlling the interface. The driving performance, task completion times, perceived workload and overall user satisfaction were evaluated. The experiment proved that both auditory interfaces were effective to use in a mobile environment, but were not faster than the visual interface. In the case of shorter tasks, e.g. changing the active profile or deleting an image, the task completion times were comparable for all interfaces; however, both the driving performance was significantly better and the perceived workload was lower when using the auditory interfaces. The test subjects also reported a high overall satisfaction with the auditory interfaces. The latter were labelled as easier to use, more satisfying and more adequate for performing the required tasks than the visual interface. The results of the survey are not surprising as there is a stronger competition for the visual attention between the visual interface and the primary task (driving the car) than in the case of using the auditory interface. So although both types of interfaces were proven to be effective, the visual interface was less efficient as it strongly distracted the user from performing the primary task.     

Comparison of Cognitive Modeling and User Performance Analysis for Touch Screen Mobile Interface Design

The aim of this study is to analyze and comparatively evaluate the usability of touch screen mobile applications through cognitive modeling and end-user usability testing methodologies. The study investigates the accuracy of the estimated results of a cognitive model produced for touch screen mobile phone interfaces. A mobile wallet application was chosen as the mobile software. The CogTool modeling tool was used as the cognitive modeling method. Eight tasks were determined and user tests were conducted in a usability laboratory with 10 participants. The tasks were compared on the basis of step time and total task completion time. This study reveals that CogTool gives approximate estimations with actual user performance on touch screen mobile phone application interfaces. However, if there are special cases in the tasks such that users are very accustomed to the steps or decision-making that is involved in the tasks, the “Think Operation” in CogTool should be modified.     

Insights from Dividing 3D Goal-Directed Movements into Meaningful Phases

Existing measures for evaluating user performance on interaction tasks in virtual environments don't often provide sufficient information for improving these interactions. A new method for analyzing 3D goal-directed movements divides them into meaningful phases. The authors applied this method to experimental data collected for a 3D task resembling a standardized 2D multidirectional pointing task (ISO 9241-9). The results and analysis demonstrate that the method provides a more detailed insight into 3D goal-directed movements. This analysis can help researchers better identify input devices' and interaction techniques' strengths and weaknesses. This article is part of a special issue on 3D user interfaces.     

A framework to design 3D interaction assistance in constraints-based virtual environments

The equilibrium of complex systems often depends on a set of constraints. Thus, credible virtual reality modeling of these systems must respect these constraints, in particular for 3D interactions. In this paper, we propose a generic framework for designing assistance to 3D user interaction in constraints-based virtual environment that associates constraints, interaction tasks and assistance tools, such as virtual fixtures (VFs). This framework is applied to design assistance tools for molecular biology analysis. Evaluation shows that VF designed using our framework improve effectiveness of the manipulation task.     

A human motor behavior model for distal pointing tasks

Models of human motor behavior are well known as an aid in the design of user interfaces (UIs). Most current models apply primarily to desktop interaction, but with the development of non-desktop UIs, new types of motor behaviors need to be modeled. Distal pointing—pointing directly at a target that is remotely situated with respect to the input device—is such a motor behavior. A model of distal pointing would be particularly useful in the comparison of different interaction techniques, because the performance of such techniques is highly dependent on user strategy, making controlled studies difficult to perform. Inspired by Fitts’ law, we studied four possible models and concluded that movement time for a distal pointing task is best described as a function of the angular amplitude of movement and the angular size of the target. Contrary to Fitts’ law, our model shows that the angular size has a much larger effect on movement time than the angular amplitude and that the growth in the difficulty of the tasks is quadratic, rather than linear. We estimated the model's parameters experimentally with a correlation coefficient of 96%.     

A task-based cognitive model for user-network interaction: defining a task taxonomy to guide the interface designer

Consistency has generally been viewed as a desirable characteristic of human-computer interfaces. Its significance is increased in the design of interfaces to open network environments, involving heterogeneous assortments of hardware and software, lack of central authority, and a constantly changing (and growing) user community. This paper addresses consistency with respect to the tasks that an interface should support in the virtual communication link between a user and any network-based application. A cognitive model was constructed to provide a meaningful framework for the development of a hierarchically structured set of tasks. An initial set of 143 tasks was composed and defined. Then, using an extensive questionnaire, a group of expert users of computer networks was asked to evaluate the hypothesized tasks. This process resulted in a task hierarchy with 89 leaf nodes representing basic tasks. The task definitions are outlined in an appendix. The cognitive model, task sets and task evaluation technique are intended to have practical utility for engineers, system designers, and software developers of user interfaces to complex systems. To illustrate their use, a prototype system was implemented and is briefly described.     

面向协作交互任务的资源模型

提出一种面向协作交互任务的资源模型.首先分析了现有协作任务分析方法和资源模型;然后在总结典型协作交互任务的基础上,提出了基于分布式认知的协作资源模型,描述了模型的组成结构和交互策略;最后给出了模型的使用模式和一个基于此模型的笔式协作概念图实例.分析表明,该模型能有效地支持协作交互,建立符合认知特点的协作用户界面.     

移动终端三维用户界面的可用性评估

本文针对移动终端的三维用户界面进行了可用性评估.从系统性能,任务绩效和用户偏好三个方面进行了全面的考察.物体选取是三维用户界面中基础的交互任务,我们结合实验数据分析,基于二维环境下的指点模型,提出并验证了一个新的基于三维用户界面的通用性能模型.同时通过用户调查和问卷分析,说明了三维用户界面在移动终端上具有较高的用户偏好.     

Context-driven interaction in immersive virtual environments

There are many interaction tasks a user may wish to accomplish in an immersive virtual environment. A careful examination of these tasks reveals that they are often performed under different contexts. For each task and context, specialized interaction techniques can be developed. We present the context-driven interaction model: a design pattern that represents contextual information as a first-class, quantifiable component within a user interface and supports the development of context-sensitive applications by decoupling context recognition, context representation, and interaction technique development. As a primary contribution, this model provides an enumeration of important representations of contextual information gathered from across the literature and describes how these representations can effect the selection of an appropriate interaction technique. We also identify how several popular 3D interaction techniques adhere to this design pattern and describe how the pattern itself can lead to a more focused development of effective interfaces. We have constructed a formalized programming toolkit and runtime system that serves as a reference implementation of the context-driven model and a discussion is provided explaining how the toolkit can be used to implement a collection of representative 3D interaction interfaces.     

Recognition, prediction, and planning for assisted teleoperation of freeform tasks

The approach of inferring user’s intended task and optimizing low-level robot motions has promise for making robot teleoperation interfaces more intuitive and responsive. But most existing methods assume a finite set of candidate tasks, which limits a robot’s functionality. This paper proposes the notion of freeform tasks that encode an infinite number of possible goals (e.g., desired target positions) within a finite set of types (e.g., reach, orient, pick up). It also presents two technical contributions to help make freeform UIs possible. First, an intent predictor estimates the user’s desired task, and accepts freeform tasks that include both discrete types and continuous parameters. Second, a cooperative motion planner continuously updates the robot’s trajectories to achieve the inferred tasks by repeatedly solving optimal control problems. The planner is designed to respond interactively to changes in the indicated task, avoid collisions in cluttered environments, handle time-varying objective functions, and achieve high-quality motions using a hybrid of numerical and sampling-based techniques. The system is applied to the problem of controlling a 6D robot manipulator using 2D mouse input in the context of two tasks: static target reaching and dynamic trajectory tracking. Simulations suggest that it enables the robot to reach intended targets faster and to track intended trajectories more closely than comparable techniques.     

Two-handed tangible interaction techniques for composing augmented blocks

Modeling tools typically have their own interaction methods for combining virtual objects. For realistic composition in 3D space, many researchers from the fields of virtual and augmented reality have been trying to develop intuitive interactive techniques using novel interfaces. However, many modeling applications require a long learning time for novice users because of unmanageable interfaces. In this paper, we propose two-handed tangible augmented reality interaction techniques that provide an easy-to-learn and natural combination method using simple augmented blocks. We have designed a novel interface called the cubical user interface, which has two tangible cubes that are tracked by marker tracking. Using the interface, we suggest two types of interactions based on familiar metaphors from real object assembly. The first, the screw-driving method, recognizes the user??s rotation gestures and allows them to screw virtual objects together. The second, the block-assembly method, adds objects based on their direction and position relative to predefined structures. We evaluate the proposed methods in detail with a user experiment that compares the different methods.     

Safe and intuitive manual guidance of a robot manipulator using adaptive admittance control towards robot agility

Key areas of robot agility include methods that increase capability and flexibility of industrial robots and facilitate robot re-tasking. Manual guidance can achieve robot agility effectively, provided that a safe and smooth interaction is guaranteed when the user exerts an external force on the end effector. We approach this by designing an adaptive admittance law that can adjust its parameters to modify the robot compliance in critical areas of the workspace, such as near and on configuration singularities, joint limits, and workspace limits, for a smooth and safe operation. Experimental validation was done with two tests: a constraint activation test and a 3D shape tracing task. In the first one, we validate the proper response to constraints and in the second one, we compare the proposed approach with different admittance parameter tuning strategies using a drawing task where the user is asked to guide the robot to trace a 3D profile with an accuracy or speed directive and evaluate performance considering path length error and execution time as metrics, and a questionnaire for user perception. Results show that appropriate response to individual and simultaneous activation of the aforementioned constraints for a safe and intuitive manual guidance interaction is achieved and that the proposed parameter tuning strategy has better performance in terms of accuracy, execution time, and subjective evaluation of users.     

用户界面设计中任务建模方法研究

基于模型的用户界面设计方法是通过用户界面模型开发用户界面的新方法。任务模型作为其中一个主要模型,刻画的是用户与界面交互过程中动态行为方面的信息。详细介绍了HTA,UAN,GOMS,CTT,Wisdom五种常用的任务模型建模方法,分析了各方法的优缺点及适用环境,并对任务建模方法的未来发展方向进行了展望。     

Directional bias in scrolling tasks: a study of users' scrolling behaviour using a mobile text-entry strategy

Mobile devices with limited interaction controls often employ cyclic scrolling for retrieval tasks. In this paper the scrolling behaviour of users entering text using a tree-key input technique based on two-phase cyclic character scrolling is studied. The results show that users have a tendency to scroll more from left-to-right than from right-to-left. However, users do also use the right-to-left functionality to both speed up their text entry task by choosing the shortest path and to make navigational corrections, suggesting that it is appropriate to provide bidirectional scrolling functionality in user interfaces on constrained mobile devices. In situations where a device architect is constrained to providing only unidirectional scrolling, the results suggest that a right-directional design is preferred over a left-directional design.     

Automatic support for usability evaluation

The main goal of the work is to propose a method to evaluate user interfaces using task models and logs generated from a user test of an application. The method can be incorporated into an automatic tool which gives the designer information useful to evaluate and improve the user interface. These results include an analysis of the tasks which have been accomplished, those which failed and those never tried, user errors and their type, time related information, task patterns among the accomplished tasks, and the available tasks from the current state of the user session. This information is also useful to an evaluator checking whether the specified usability goals have been accomplished     

Comparing Parameter Manipulation with Mouse, Pen, and Slider User Interfaces

Visual fixation on one's tool(s) takes much attention away from one's primary task. Following the belief that the best tools 'disappear' and become invisible to the user, we present a study comparing visual fixations (eye gaze within locations on a graphical display) and performance for mouse, pen, and physical slider user interfaces. Participants conducted a controlled, yet representative, color matching task that required user interaction representative of many data exploration tasks such as parameter exploration of medical or fuel cell data. We demonstrate that users may spend up to 95% fewer visual fixations on physical sliders versus standard mouse and pen tools without any loss in performance for a generalized visual performance task.     

基于PCTBTA任务模型的用户界面开发方法

为了适应普适计算环境中用户、设备、使用环境和开发平台的多样性,基于模型的方法被应用于用户界面开发过程中,试图在抽象层次上描述界面,通过模型转换,使其适用于不同的平台.然而,由于目前基于模型的用户界面开发方法（model-based user interface development,简称MBUID）中所采用任务模型的局限性,致使生成的界面难以满足动态环境下用户的可用性需求.提出一种基于任务模型的用户界面开发框架,旨在建模和生成有效、高效、令用户满意的用户界面.在可用性方面,为了准确描述普适计算环境中用户任务,提出一种基于感知控制理论的任务分析方法（perceptual-control-theory-based task analysis,简称PCTBTA）,将使用上下文信息引入到任务分析过程中,并且在较高的抽象层次上反映交互的内容,给可用性设计提供任务空间;在技术方面,为PCTBTA任务模型向界面模型的转换提供技术支持.最后,通过实例说明所提出方法的可行性,并通过与其他方法在可用性和性能方面的比较,表明该方法的有效性.     

人机交互中基于时间约束的人体工效模型

针对人机交互领域速度-准确度折中关系的预测中任务完成精确度的预测模型较为欠缺的问题,提出了一种基于时间约束的精确度模型预测方法。该方法采用了人机交互研究中常用的受控实验测试分析法,研究了在计算机用户界面中要求用户在给定的时间内完成任务时,任务完成的精确度与给定的时间约束之间的折中关系,用以衡量完成时间约束任务的人体工效。实验中设计了一系列受时间约束的轨道滑动任务,实验环境中自变量包括轨道长度、轨道宽度以及规定的在轨道中滑动的时间,因变量为任务完成的精确度,采用在轨道中滑动时轨迹的纵向偏差表示。通过对30位被试者实验数据的分析发现,任务完成的精确度与轨道宽度以及滑动速度(表示为轨道长度/规定的滑动时间)之间构成线性的关系,在此基础上采用最小二乘方回归法建立了一个基于时间约束的任务完成精确度的量化模型;该模型与真实实验数据集的拟合优度达到了0.857。