Evaluation of four cursor control devices during a target acquisition task for laparoscopic tool control

Current laparoscopic surgery instruments create awkward postures which produce fatigue and pressure points in surgeons. In order to alleviate some of this discomfort a new laparoscopic tool had been developed with the inclusion of an articulating end-effector manipulated by a trackball. The current study was developed to access the performance of four input devices which could replace the manual trackball in a powered laparoscopic tool. A simple Fitts’ law task was conducted and the devices’ performance was evaluated with both subjective and objective measures. This article makes three main contributions to the scientific community. First, it provides a comparison of four control devices (TouchPad, Mouse Button Module, MiniJoystick Module and MicroJoystick) for use in a powered laparoscopic tool. Second, it provides an understanding of how the non-traditional measure of target re-entry can be utilized to compare control devices and how this relates to the more traditional measures of throughput and error rate. Finally, it contributes to the understanding of how a user's familiarity with a control device could affect the subjective and objective performance of the device. The main results indicate that the TouchPad and MicroJoystick are the best candidate-devices for use in a powered laparoscopic tool. The article also provides support for utilizing the new measure target re-entry when comparing control performance. Although studied in the application of laparoscopic surgery, the results can be generalized for the design of any hand-held device in which the speed and accuracy of the control device is critical.     

Information society and information technology

To investigate the characteristics of a computer touchpad as a pointing device, 14 participants used their right hand to manipulate the touchpad on a laptop computer. They were required to move a cursor over different distances (7.5 cm, 15 cm) from a home location to targets of different diameters (8 mm, 16 mm), situated to the upper left, middle, or right of a computer screen. A kinematic analysis of movement onsets and cursor trajectories indicated the nature of inefficiencies of the touchpad compared with other devices, primarily excessive submovements. Upper leftward movements were poorer, which can be explained by asymmetries in the finger-wrist system. This result implies that screen accessibility can vary as a function of users' interaction with cursor controllers and that the default placements of key icons might need to vary as a consequence.     

Gain effects on performance using a head-controlled computer input device.

The purpose of this study was to use a Fitts' task to (1) determine how control-display gain influences performance using a head-controlled computer input device; (2) compare relative sensitivity to gain and optimal gain between head control and hand/arm control; and (3) investigate control-display gain interactions with other task factors including target width, movement amplitude and direction. The task was a discrete target acquisition task using circular targets of 2.9 mm, 8.1 mm, and 23.5 mm, movement amplitudes of 24.3 mm and 61.7 mm, and eight radial directions including 0 degrees, 45 degrees, 90 degrees, 135 degrees, 180 degrees, 225 degrees, 270 degrees, and 315 degrees. Each device was operated at four gain levels. Ten subjects participated. The results indicated that gain had a significant effect on movement time for both types of pointing devices and exhibited local minimums. Discrete target acquisition at all gains was aptly described using Fitts' Law for both input devices. The mouse gain resulting in minimum movement time and RMS cursor deviation was between 1.0 and 2.0. The minimum movement time and RMS cursor deviation for the head-controlled pointer occurred at a gain between 0.3 and 0.6. Average movement time at the optimal head-controlled pointer gain had a slope of 169 ms/bit and was more than 76% greater than at the optimal mouse gain with a slope of 135 ms/bit. In addition, average RMS displacement was more than 27% greater for the head-controlled pointer at its optimal gain setting than for the mouse. Gain had the greatest effect for small target widths and long movement amplitudes using the head-controlled pointer. Average movement time increased 37% when increasing the head-controlled pointer gain from 0.6 to 1.2 for the small target width, but only increased 0.3% when increasing gain for the large target width. Average movement time also increased 12% when decreasing the head-controlled pointer gain from 0.3 to 0.15 for the long movement amplitude, but decreased 0.3% when decreasing gain for the short movement amplitude.     

The use of cursor measures for motion-impaired computer users

“Point and click” interactions remain one of the key features of graphical user interfaces (GUIs). People with motion-impairments, however, can often have difficulty with accurate control of standard pointing devices. This paper discusses work that aims to reveal the nature of these difficulties through analyses that consider the cursor’s path of movement. A range of cursor measures was applied, and a number of them were found to be significant in capturing the differences between able-bodied users and motion-impaired users, as well as the differences between a haptic force feedback condition and a control condition. The cursor measures found in the literature, however, do not make up a comprehensive list, but provide a starting point for analysing cursor movements more completely. Six new cursor characteristics for motion-impaired users are introduced to capture aspects of cursor movement different from those already proposed. Published online: 6 November 2002     

Forward/up directional incompatibilities during cursor placement within graphical user interfaces

Within graphical user interfaces, an indirect relationship between display and control may lead to directional incompatibilities when a forward mouse movement codes upward cursor motions. However, this should not occur for left/right movements or direct cursor controllers (e.g. touch sensitive screens). In a four-choice reaction time task, 12 participants performed movements from a central start location to a target situated at one of four cardinal points (top, bottom, left, right). A 2 x 2 x 2 design varied directness of controller (moving cursor on computer screen or pen on graphics tablet), compatibility of orientation of cursor controller with screen (horizontal or vertical) and axis of desired cursor motion (left/right or up/down). Incompatibility between orientation of controller and motion of cursor did not affect response latencies, possibly because both forward and upward movements are away from the midline and go up the visual field. However, directional incompatibilities between display and controller led to slower movement with prolonged accelerative phases. Indirect relationships between display and control led to less efficient movements with prolonged decelerative phases and a tendency to undershoot movements along the bottom/top axis. More direct cursor control devices, such as touch sensitive screens, should enhance the efficiency of aspects of cursor trajectories.     

Forward/up directional incompatibilities during cursor placement within graphical user interfaces

Within graphical user interfaces, an indirect relationship between display and control may lead to directional incompatibilities when a forward mouse movement codes upward cursor motions. However, this should not occur for left/right movements or direct cursor controllers (e.g. touch sensitive screens). In a four-choice reaction time task, 12 participants performed movements from a central start location to a target situated at one of four cardinal points (top, bottom, left, right). A 2 × 2 × 2 design varied directness of controller (moving cursor on computer screen or pen on graphics tablet), compatibility of orientation of cursor controller with screen (horizontal or vertical) and axis of desired cursor motion (left/right or up/down). Incompatibility between orientation of controller and motion of cursor did not affect response latencies, possibly because both forward and upward movements are away from the midline and go up the visual field. However, directional incompatibilities between display and controller led to slower movement with prolonged accelerative phases. Indirect relationships between display and control led to less efficient movements with prolonged decelerative phases and a tendency to undershoot movements along the bottom/top axis. More direct cursor control devices, such as touch sensitive screens, should enhance the efficiency of aspects of cursor trajectories.     

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.     

Using cursor measures to investigate the effects of impairment severity on cursor control for youths with cerebral palsy

Individuals with upper limb impairments due to cerebral palsy encounter difficulties when using pointing devices and can be limited in communicating and accessing education tools through computers. Analysis of cursor trajectories can identify some of the factors limiting cursor movement, and provide a better understanding of human movement to assist in designing accessible computer interfaces. This study evaluated cursor trajectories from 29 individuals with bilateral cerebral palsy (CP) and different levels of function. The functional level was classified based on the MACS (Manual Ability Classification System). Results show that the contributors to a model that assesses different MACS levels are the movement time, acceleration–deceleration cycles and average speed. The model appears unaffected by accuracy measures. For both typically-developed youth and participants with CP, a good model of index of difficulty must include the following predictors: rapidity – movement time, average speed, zero acceleration crossings and accuracy, trajectory distance, linearity index, and indices of vertical and horizontal components. Models for those who are typically-developed should also include an index of diagonal component and curvature index.     

Effects of sensorimotor transformations with graphical input devices

The impact of sensorimotor transformations with graphical input devices is surveyed with regard to action control. Recent evidence lets us assume that the distal action effect (the moving cursor) rather than the proximal action effect (the moving hand) determines the efficiency of tool use. In Experiment 1, different gains were explored with a touchpad and a mini-joystick. In correspondence with our assumptions the results revealed evidence that Fitts' law holds for distal action–effect movements, but less for proximal action–effect movements. Most importantly, this was not only true for the touchpad but also for the mini-joystick. We further found a more efficient use of the touchpad in comparison to the mini-joystick when a high gain was used. In Experiment 2, the dominance of the action effect on motor control was confirmed in an experiment with a digitiser tablet. The tablet amplitude was held constant, but again, movement times followed the perceived index of difficulty on the display. It is concluded that Fitts' law did not rely on the movements of the motor system, but on the distal action effects on the display (changes in visual space). Distal action–effect control plays an important role in understanding the constraints of the acquisition and application of tool transformations.     

A software system for evaluation and training of spatial reasoning and neuroanatomical knowledge in a virtual environment

This paper describes the design and development of a software tool for the evaluation and training of surgical residents using an interactive, immersive, virtual environment. Our objective was to develop a tool to evaluate user spatial reasoning skills and knowledge in a neuroanatomical context, as well as to augment their performance through interactivity. In the visualization, manually segmented anatomical surface images of MRI scans of the brain were rendered using a stereo display to improve depth cues. A magnetically tracked wand was used as a 3D input device for localization tasks within the brain. The movement of the wand was made to correspond to movement of a spherical cursor within the rendered scene, providing a reference for localization. Users can be tested on their ability to localize structures within the 3D scene, and their ability to place anatomical features at the appropriate locations within the rendering.     

Analysis of cursor movements with a mouse

With a mouse input device, 32 experienced computer users moved a cursor from a starting position to a target, both of which were displayed simultaneously on the computer’s screen. Cursor movements occurred under conditions of variations in the angle of approach to the target, the target size and shape, the distance to the target, and the nature of the task, drag-drop or point-click. In a fully crossed within-subjects design, all variables studied significantly affected movement time. Fitts’ law accounted for 44% or 97% of the variance in movement time, depending on the method of analysis. Fitts’ law was not equally effective under all combinations of the variables studied. An analysis of residuals showed that residuals were smaller for a point-click task in comparison to a drag-drop task, and residuals were lowest for the largest target displayed at the shortest distance from the starting position. The application of Fitts’ law to cursor movements with a mouse should be qualified by noting the conditions under which the movements were observed.     

Gender Differences in Mouse and Cursor Movements

Computer cursor and mouse activities such as moving, pointing, selecting, and dragging are essential parts of everyday interactions. Yet it is unknown how men and women differ in the way they move computer cursors. This study examines gender differences in movements of computer cursors. In one experiment, the authors measured trajectories of computer cursors every 20 ms in a simple choice-reaching task and tested the extent to which movement features related to controlling and targeting diverge between male and female participants. Results showed significant gender differences in cursor motions. Female participants deviated from the straight path toward the target location to a larger degree than did male participants, and female participants showed more backward motions (deviating backward from the target location) than did male participants. Implications for sources of these gender differences, user interface and input device design, and musculoskeletal disorders in women are also discussed.     

基于转速反馈的动力翼伞纵向串级控制

为提高动力翼伞纵向跟踪效果,并针对现有模型及控制方法的局限性,着眼于实际飞行试验,提出一种基于转速反馈调节的串级自抗扰控制策略.首先在动力翼伞纵向模型的基础上,改进引入无刷直流电机模型,并利用转速测量装置实时更新电机转速信息,应用最小二乘法拟合电机转速与螺旋桨静推力的非线性关系.设计纵向轨迹控制器,内环实现对电机转速的...     

The use of ballistic movement as an additional method to assess performance of computer mice

This study investigates an additional method for independently evaluating performance of speed and accuracy of computer mice, based on five parameters of the initial submovement when aiming at a target. This first submovement is known to be carried out in a ballistic manner and hence the Fitts-type aiming movement may be studied by means of the established relationships for ballistic movement. To test the ballistic movement method, eight participants used four different computer mice to execute ballistic movements and Fitts-type aiming movements. Regression tests showed that the Fitts movement time was well correlated with the time and stopping-variable error of ballistic movement, implying that measuring ballistic movement parameters can predict the performance of Fitts-type aiming movements. More importantly, the use of ballistic movement method allows independent assessments of the speed and accuracy, providing additional information for input devices assessment and designs.Relevance to industryThe study illustrates the close correspondence between input device evaluation using the proposed ballistic movement method and Fitts' law. The ballistic movement method allows independent measures of speed and four types of accuracy, which should benefit input devices assessment and designs.     

液压支架手动换向阀耐久性试验自动化装置设计

针对液压支架手动换向阀耐久性试验存在测试周期长、效率低、无法实现自动测试的问题,设计了一种液压支架手动换向阀耐久性试验自动化装置.该装置基于液压油缸往复运动,结合使用被试手动换向阀手柄推拉专用工装,带动被试手动换向阀手柄左右摆动,达到自动换向目的.同时,利用测控系统软件控制装置启动、换向、采集压力、判断计数等动作,从而实现被试手动换向阀耐久性试验的自动化测试.实际应用结果表明:该装置具有结构简单、加载速度可调、试验效率高的特点,耐久性试验周期由原来的165.6 h缩短至31.2 h.     

Communication system using EOG for persons with disabilities and its judgment by EEG

The aim of this study was to present electrooculogram (EOG) signals that can be used for human computer interface efficiently. Establishing an efficient alternative channel for communication without overt speech and hand movements is important to increase the quality of life for patients suffering from amyotrophic lateral sclerosis (ALS) or other diseases that prevent correct limb and facial muscular responses. Using EOG signals, it is possible to improve the communication abilities of those patients who can move their eyes. Investigating the possible usage of the EOG for human–computer interface, a relation between sight angle and EOG is determined. In other methodology, most famous approaches involve the use of a camera to visually track the eye. However, this method has problems that the eyes of user must always be open. In this paper, we propose the mouse cursor control system for ALS patients using EOG and electroencephalograph (EEG) signals. We introduced the algorithm using alternating current and direct current of EOG corresponding to the drift. Therefore, EOG measurement system we proposed improved the problems of artifacts caused by eye blinking which was not accepted for other systems, the displacement of electrode positions and the drift. In addition, we introduced the EEG measurement to examine whether the subject could control their eye movement consciously. The EEG signals were not used to control the mouse movement, but to determine the subject’s control state. In order to test whether our system works well, we prepared a questionnaire and asked the subjects to operate our system, and answer with YES or NO by moving the mouse cursor. During the task, we also recorded the subjects’ EEG by MYNDPLAY [7] and checked their conscious level. Three subjects participated in this experiment, and they had never operated this system before. In this experiment, we measured 30 states of EEG signals while EOG was also measuring for one eye movement and analyzed the EEG signals. The results of analysis of the EEG signal changes and the answers to questions indicated that at 26 of 30 states, the subjects’ conscious level while they were moving the cursor by EOG signals was correctly determined from the EEG signals. From these results, we could know that the EEG signals can be used to adjust the EOG system whether it works according to patients’ mind or just a misjudgment.     

Use of voice input to enhance cursor control in mainstream gaming applications

There are opportunities for use of voice input to enhance the effectiveness of continuous cursor control in mainstream gaming. This paper describes a program that uses voice input to manipulate the cursor gain parameter within the context of a game. For some use groups the ability to dynamically manipulate this parameter can be important in making games more accessible. The program makes use of readily-available speech technology, and can be used in conjunction with existing games.     

Speed–accuracy tradeoffs in specialized keyboards

Patients with locked-in syndrome are perceptually and cognitively aware of their environment but are unable to speak and have very limited motor capabilities. These patients frequently use a virtual keyboard with a cursor that moves over different items. The user triggers a selector when the cursor is over the desired item. For text entry such a method is excruciatingly slow, but is critical for patients who otherwise cannot communicate. We show how such keyboards can be optimally designed to maximize text entry speed while simultaneously controlling the entry error rate. The described method quantifies how different factors in keyboard design influence both entry speed and accuracy and demonstrates that different keyboard designs can greatly alter the efficiency of keyboard use. For a given text corpus and allowable average entry error proportion, the method identifies the cursor duration and character layout that minimizes average entry time. The method can easily be adapted to a variety of keyboard designs and selection devices and thereby improve the communication of locked-in syndrome patients.     

面向微粒操纵的介电泳芯片系统研究

针对目前在纳米器件及传感器的制造中尚无对大量粒子进行有效操纵的方法,我们利用介电泳方法对大量微粒进行定位和传输操纵,介绍了利用MEMS工艺进行介电泳芯片加工的过程以及整个观测与实验系统的建立,通过有限元软件对传统介电泳和行波介电泳中电极阵列的电场分布进行求解,并在该实验系统下实现了对微通道中的悬浮高度和微粒的运动速度的测量.该实验系统的研究为液体环境下微纳颗粒的装配和分离提供了一条有效的技术路径.