Device deformation allows new types of gestures to be used in interaction. We identify that the gesture/use-case pairings proposed by interaction designers are often driven by factors relating improved tangibility, spatial directionality and strong metaphorical bonds. With this starting point, we argue that some of the designs may not make use of the full potential of deformation gestures as continuous, bipolar input techniques. In two user studies, we revisited the basics of deformation input by taking a new systematic look at the question of matching gestures with use cases. We observed comparable levels of UX when using bend input in different continuous bipolar interactions, irrespective of the choice of tangibility, directionality and metaphor. We concluded that device bend gestures use their full potential when used to control continuous bipolar parameters, and when quick reactions are needed. From our studies, we also identify relative strengths of absolute and relative mappings, and report a Fitts' law study for device bending input.

What is a device bend gesture really good for

Needle insertion is the most basic skill in medical care, and training has to be imparted not only for physicians but also for nurses and paramedics In most needle insertion procedures, haptic feedback from the needle is the main stimulus in which novices need training For better patient safety, the classical methods of training the haptic skills have to be replaced with simulators based on new robotic and graphics technologies This paper reviews the current advances in needle insertion modeling, classified into three sections: needle insertion models, tissue deformation models, and needle–tissue interaction models Although understated in the literature, the classical and dynamic friction models, which are critical for needle insertion modeling, are also discussed The experimental setup or the needle simulators that have been developed to validate the models are described The need of psychophysics for needle simulators and psychophysical parameter analysis of human perception in needle insertion are discussed, which are completely ignored in the literature

Haptic Feedback in Needle Insertion Modeling and Simulation

Fitts’ law has been widely used in the human-computer interaction (HCI) field, especially for Graphical User Interface (GUI) design. However, most studies on Fitts’ law were performed with motion control tasks under visual feedback while only a few endeavor to measure human force control behavior. How quickly humans can exert a constant force with a required accuracy and whether this speed-accuracy tradeoff obeys Fitts’ law still needs to be explored. In this paper, human capabilities for controlling absolute magnitudes of fingertip force with discrete visual/audio/haptic feedback cues were observed and compared. Eighteen participants applied constant forces by pressing a force sensor with their index fingers in the three feedback modes respectively. Response time of 24 pairs (4 × 6) of Magnitude-Tolerance conditions were measured. The results showed that the response time obeyed Fitts’ law within a certain range of force accuracy in all the three feedback modes, while the Linear speed-accuracy tradeoff model was almost superior for the force control process than the Meyer formulation and the Shannon formulation. The response time in the audio feedback mode was the shortest among the three feedback conditions. The results may be used as guidelines for applications that rely on accurate and quick force control under different feedback conditions such as fast tapping tasks on a touch screen.

Speed-accuracy tradeoff of fingertip force control with visual/audio/haptic feedback

Estimation of the force applied to the tip of a surgical instrument is necessary to render high-fidelity haptic feedback. Accuracy of the force estimation suffers from friction caused by the rubber packing inside the trocar. This paper proposes a 3-DOF force sensor installed to the trocar support. It is possible to estimate the 2-DOF radial force applied to the instrument tip and the 1-DOF axial friction occurring in the trocar by using the 3-DOF force sensor. Accuracy of the estimation, however, deteriorates due to the reaction moment that occurs at the trocar support. An I-shaped force sensor is designed to reduce coupling effect which is caused by the reaction moment. Design parameters of the sensor are optimized to minimize the coupling effect by using ANSYS software. The sensor is manufactured and calibrated using the least-square calibration method. L2 relative error of the estimation of the radial force applied to the instrument tip is less than 6.30 %. The axial reaction force corresponding to the friction is also estimated with relative error less than 8.63 %.

A 3-DOF sensor to estimate the force applied to the tip of a surgical instrument

[Purpose] The aim of this study was to determine the reliability of a newly designed dynamometric device for use in frequent force producing/reproducing tasks on the knee joint. [Subjects and Methods] In this cross-sectional study (Development & Reliability), 30 young healthy males and females (age 23.4 ± 2.48 years) were selected among students of Tabriz University of Medical Sciences by simple randomized selection. The study instrument was designed to measure any isometric contraction force exerted by the knee joint flexor/extensor muscles, known as the ipsilateral and contralateral methods. Participant knees were fixed in 60° flexion, and each participant completed the entire set of measurements twice, 72 hours apart. [Results] The findings showed a good intraclass correlation coefficient of 0.73 to 0.81 for all muscle groups. The standard error of measurement and smallest detectable difference for flexor muscle groups were 0.37 and 1.02, respectively, while the values increased to standard error of measurement=0.38 and smallest detectable difference=1.05 for extensor muscle groups. [Conclusion] The device designed could quantify the forces producing/reproducing tasks on the knee joint with a high rate of reliability, and can probably be applied for outcome measurements in proprioceptive assessment of the knee joint.

https://www.jstage.jst.go.jp/article/jpts/28/8/28_jpts-2016-234/_pdf

Measurement of force sense reproduction in the knee joint: application of a new dynamometric device.

The paper aims at deriving the Just Noticeable Difference (JND) for force magnitude recognition between left and right index finger of human hand The experiment involves establishment of an internal reference stimulus, using the left index fingers of the hand, by the subject, which is perceived and matched under contra-lateral force matching paradigm A combination of virtual environment and a force sensor was used to derive the just noticeable difference for index-finger force application Six voluntary healthy young adult subjects in the age group of 22–30 years were instructed to produce reference forces by left index finger and to reproduce the same amount of force by the right index finger, when the subjects were confident enough of matching same amount of force, the force values of the both the left and right index finger were recorded simultaneously for 5 s at 10 Hz Five different trials were conducted for different force levels ranging from 2 to 5 N The percentage real JND and absolute JND were derived for all the subjects It was found that the Force-JND obtained was approximately 10 % across all subjects Results also show that subjects tend to underestimate force at high force levels and overestimate at low force levels The results obtained can be used as basic building block for the calibration of virtual reality based minimally invasive surgery related tasks and force based virtual user interfaces ranging from touch pad to assistive tools

/pdf/force-jnd-for-right-index-finger-using-contra-lateral-force-3efyudbk5d.pdf

Force JND for Right Index Finger Using Contra Lateral Force Matching Paradigm

Conventional Fitts’s model for human movement task finds a common application in modern day interactive computer systems and ergonomics design. According to Fitts’s law the time required to rapidly move to a target area is a function of the distance to the target and the size of the target. This paper describes experimental process for prediction of minimum movement time, in a force-variation based human performance task involving right index finger. In this study we have made an attempt to extend the applicability of the conventional Fitts’s model for a force based virtual movement task, without taking position into account and evaluate human performance metrics for such tasks. An experiment was conducted in which 6 healthy young adult subject’s in the age group of 22–30 years performed force based movement tasks. During each trial, subjects were asked to reach an initial force bar of given thickness W Newtons, corresponding to allowable tolerance. Once the subject’s had reached initial level, they were instructed to reach out the target force bar of same thickness W as quickly as possible and bring it back to the initial force level bar, thereby completing 1 iteration. Time required for 10 such iteration was noted for each subject. The results from the experiment show that the relationship between movement time and index of difficulty for force tasks are well described by Fitts’s law in visual guided, force-based virtual movement task.

/pdf/modeling-of-human-hand-force-based-tasks-using-fitts-s-law-24gib7mcb1.pdf

Sunny Purswani

Papers

Force JND for Right Index Finger Using Contra Lateral Force Matching Paradigm

Modeling of Human Hand Force Based Tasks Using Fitts's Law