Defining Allowable Stimulus Ranges for Position and Force Controlled Cutaneous Cues.

Extended-Reality Technologies: An Overview of Emerging Applications in Medical Education and Clinical Care.

The Effects of Environmental Haptic Cues on Consumer Perceptions of Retailer Warmth and Competence

This installation provides painters with a method for feeling attributes of digital and a fluid canvas. When a user of this installation moves the stylus paintbrush over the digital canvas, he/she senses the of the colors through the brush. For example, the user experiences dark as heavy in weight and light as light in weight. Complex painting is expressed as a mixed tactile sensation using a new desk-style force feedback system called the Proactive Desk. Other existing digital painting systems that use haptic cues usually aim to be physically and visually correct. In this approach, however, we invested effort in enhancing the relationship between digital as a virtual material and the sense of touch. Additionally, we took the importance of co-located drawing work space for creative tasks into account. We believe that this experience will arouse new inspiration and give digital painters the opportunity to experience again how important touch is for creativity in art.

Soft robotic grippers possess high structural compliance and adaptability, allowing them to grasp objects with unknown and irregular shapes and sizes. To enable more dexterous manipulation, soft sensors that are similar in mechanical properties to common elastomer materials are desired to be integrated into soft grippers. In this paper, we develop ionic hydrogel-based strain and tactile sensors and integrate these sensors into a three-finger soft gripper for learning-based object recognition and force-controlled grasping. Such hydrogel-based sensors have excellent conductivity, high stretchability and toughness, good ambient stability, and unique antifreezing property; they can be readily attached to a soft gripper at desired locations for strain and tactile sensing. By using a deep-learning model, the sensory soft gripper is demonstrated to be capable of grasping and recognizing objects at both room and freezing temperatures, and achieving close to 100% recognition accuracy for ten typical objects. Moreover, the capacitive tactile feedback of the gripper is utilized to develop a closed-loop force controller and realize force-controlled grasping of fragile or highly deformable objects. A new slip detection and compensation strategy is also proposed and validated for the sensory gripper for adjusting the grasping force in real time upon detecting slippage. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Note to Practitioners</i> —The multimodal sensation of a soft robotic gripper could enrich its grasping functionalities and improve its manipulation performance. This research integrates novel antifreezing ionic hydrogel-based strain and tactile sensors into a three-finger soft robotic gripper for learning-based object recognition and force-controlled grasping. Constructed from a highly stretchable, ambient-stable, and antifreezing ionic hydrogel, the strain and tactile sensors can be readily integrated at the desired locations on the soft gripper, and can reliably operate at both ambient and freezing temperatures with excellent mechanical and electrical properties. Based on the feedback of the strain and tactile sensors, a deep learning model is employed to enable high-accuracy object recognition while grasping, which can be useful for manipulation in vision-free environments. Closed-loop force control and slip compensation strategies are also demonstrated for reliably grasping fragile/deformable objects and handling slip events during the manipulation of heavy objects. The sensory soft gripper and the associated object recognition and force control methods could find practical applications in a variety of robotic manipulation tasks.

A computer program is described that measures body size distortion and body dissatisfaction. The program is written using Visual Basic development tools and will run on any Windows 98 or more current system. The width of a static digital image of the participant can be manipulated using three separate psychophysical methods. In the method of adjustment, the participant adjusts the image wider or thinner to match his or her perceived size. The participants may also be required to adjust the image to their ideal size, with the discrepancy between perceived and ideal size being used as a measure of body dissatisfaction. In the staircase method, participants see an image that is continuously expanding or contracting. The participants change the direction of the distortion when the image matches their perceived size. In the adaptive probit estimation procedure, participants judge whether a static image is distorted too wide or too thin. Analysis of the responses permits a determination of the point of subjective equality (PSE) and the difference limen (DL) values. The DL reflects the amount of body size distortion necessary for the participant to detect the distortion 50% of the time. The PSE reflects the participant's subjective judgment of his or her body size. These two values are reflective of the sensory and nonsensory components, respectively, that contribute to body size judgments.

At low sound frequencies, spikes in the auditory nerve (AN) are phase-locked to the stimulus waveform. For sinusoidal stimuli, spike occurrences are restricted to the positive half-waves of the sound cycles, which constraints possible values of spike rates and their variability. As the spike rates are used for representation of sound intensity, the just noticeable differences (JNDs) of sound level and of inter-aural level difference (ILD) will be influenced. Due to the lack of appropriate AN data, we explore the topic using a computational model [1]. Three possible types of spike trains are considered: a synchronous, an asynchronous spike train with variable intensity, and a periodically restarting (with sound period) asynchronous process. Generally, the synchronous process leads to several times lower JNDs than the other processes. The JNDs depend on further parameters: longer counting windows or higher number of converging fibers result in smaller JNDs, larger spike timing jitter (random displacement of spikes from their ideal position) slightly increases the JNDs. Notably, the dependence of JNDs on mean spike rate is in contradiction to psychophysical observations that report monotonic decrease of JND of intensity with increasing sound pressure level, the so called near-miss to Weber's law [2]. Even with ideal phase-lock and no jitter, the simulated JND of the synchronous algorithm has a bell shape, the other two algorithms give monotonically increasing function (Figure ​(Figure1A,1A, colored lines). Recruitment of more AN fibers with rising intensity overcomes this discrepancy; a simulation of this mechanism yields results well matching the psychophysical results (Figure ​(Figure1A,1A, black line). Figure 1 Just-noticeable differences of sound level depending on spike rate (A) and sound frequency (B). Another discrepancy of the modeling results with psychophysics is the simulated JND increasing with frequency, given a constant spike rate (Figure ​(Figure1B),1B), while psychophysical JNDs decrease with frequency. However, if we assume that maximum spike rate is in some way limited by the frequency (e.g., at most one spike can occur in each sound cycle) and that a given intensity range (e.g., 30 dB) is always mapped to the available range of spike rates (e.g., between zero and sound frequency), then the slope of the rate-intensity function increases and the JND decreases with frequency. The results show that intensity coding has specific properties at low sound frequencies, deserving more detailed electrophysiological studies than what is available in experimental literature today.

Cutaneous Electrohydraulic (CUTE) Wearable Devices By creating a wide range of pleasant haptic cues, cutaneous electrohydraulic (CUTE) devices unlock new opportunities for compact, lightweight, wearable consumer devices. These soft actuators can make and break contact with the skin, press steadily, and vibrate at a broad range of frequencies, bringing an engaging new dimension to digital communication. More details can be found in article number 2402461 by Christoph Keplinger, Katherine J. Kuchenbecker, and co‐workers. [Image: see text]

Nonparametric control algorithms for a pneumatic artificial muscle

The just noticeable difference (JND) in the sensory response to conjunctively presented stimuli is a widely applied psychophysical measurement. However, little is known about the JND in the perception of physical exertion. PURPOSE: To describe the JND in the perception of physical exertion during submaximal cycle ergometer exercise. METHODS: Recreationally active males (n=20) and females (n=26) (age 21.4±3.1 yr) performed cycle exercise terminating at peak intensity. Rating of perceived exertion [RPE OMNI Cycle (0-10) Scale] was estimated for the overall-body at the end of each min. Individual linear regression was used to derive the power output (PO) and oxygen consumption (VO2) corresponding to an RPE of 5. This PO served as the standard. On a separate occasion four 5-min cycle exercise bouts were performed with 5 min rest between bouts. During bouts 1 and 3 subjects cycled at the standard. During bouts 2 and 4 subjects adjusted the resistance to achieve a level of exertion above or below the standard. The difference in final 30-s VO2 between each JND bout and the previous standard was taken as the physiologic analog of the above (ΔJND-A) and below (ΔJND-B) perceived exertion JND, expressed in absolute (l·min-1) and relative (%VO2PEAK) values. ΔJND-A and ΔJND-B were compared between genders, as well as between subjects exhibiting lower and higher ventilatory breakpoints (Vpt) and VO2PEAK within genders. RESULTS: For the total sample, ΔJND-B was significantly greater (p<0.05) than ΔJND-A when expressed in absolute (0.24±0.20 l·min-1 vs. 0.17±0.13 l·min-1, respectively) and relative values (8.33±6.01 %VO2PEAK vs. 5.90±4.09 %VO2PEAK, respectively). For both males and females, there were no differences in JND values between subjects with lower and higher Vpt or VO2PEAK. CONCLUSION: It is proposed that the VO2 corresponding to a JND above and below a standard stimulus can serve as an effective tool to measure a subject's perceptual acuity. This can be used to determine an individual's ability to accurately self-regulate prescribed exercise intensities. (This is a secondary analysis of a previously reported data set which has been expanded.)

Taking virtual reality out of the game and into healthcare.

Lower body tracking and user experience analysis are ongoing challenges in immersive technologies and biomechanics research, respectively. Particularly, in immersive technologies like mixed reality, there are limited research applications in user comfort and experience, and locomotion. In this paper, we aimed to conduct a cross-disciplinary research (by combining the elements of Biomechanics and human–computer interaction) in understanding the impact of user experience and immersive technologies induced symptoms in virtual and mixed reality environments for obstacle clearance tasks. For this, we created obstacle clearance applications for Oculus Quest and Microsoft HoloLens. Also, we conducted a user study with 12 participants under two conditions (virtual reality and mixed reality) in obstacle clearance behavior of varying heights. The results from our study indicated that the levels of immersion and enjoyment were significantly higher in virtual reality compared to mixed reality. In terms of virtual reality-induced symptoms, the participants found the mixed reality environment to be slightly more comfortable than virtual reality.

In this study, a driving assistive system using an active force control for an accelerator pedal is proposed. First, using a driving simulator embedded with a haptic pedal mechanism, driver's just noticeable difference (JND) against the force perception on the pedal was investigated experimentally. Second, an algorithm of the conscious/unconscious assistive control is presented by utilizing the identified JND. Through verification experiment on the same simulator, the conscious assistive was successful with a probability of 83%. However, the unconscious assistive was failed with a probability of 79% and the drivers noticed the assist with a probability of 73%.

In this study, we were interested in the question whether vibrotactile thresholds on the back, in terms of the Just Noticeable Difference (JND), scale with back length. Although there exists only indirect physiological evidence, it could be assumed that the density of mechanoreceptors is lower if back size is larger. As a consequence, the JND would increase with back length. We measured psychophysical curves for 40 male participants with back lengths in the range of 36 to 55 cm. Nine equally spaced vibration motors were placed in vertical direction on their back, 2 cm left of the spine. For each stimulus pair, participants had to decide whether the second vibration was above or below the first vibration. It was found that the slope of the fit of the JND as a function of back length was not significantly different from zero, so contrary to our expectation, we did not find an influence of back length on JND. This means that when customizing a wearable haptic device for the back, measuring back length is not the way to go.

Hydraulic power systems have greater flexibility and can produce more power than mechanical and electrical systems of equal size. The aim of this paper is to describe results derived from an experimental study on a power hydraulic testing machine with hybrid force and position control. The paper includes the description and fabrication of this novel testing system, named electro-hydraulic load simulator (EHLS), for conducting a performance and stability test in a bench system where force or position control is important. In order to improve the control performance of the loading system and to eliminate or reduce noise, a parallel force and position control strategy using the proportional integral derivative (PID) control method, an online self-tuning fuzzy-neural mechanism, and system identification techniques are also presented in this paper. Experiments are carried out to evaluate the effectiveness of the proposed parallel force and position control method applied to the EHLS system. Copyright © 2011 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society

In this paper, model-based precision force and position control of an ionic polymer metal composite (IPMC) is presented. A 23.8 mm × 3.4 mm × 0.16 mm IPMC strip was used as an actuator in a cantilever configuration. Open-loop force and position responses of an IPMC are not repeatable, and hence closed-loop precision control is of critical importance to ensure proper functioning, repeat-ability and reliability. After feedback controllers were designed and implemented with empirically obtained fourth-order plant transfer functions, the overshoot decreased from 460 to 2.8 per cent and the settling time was reduced from 37.5 to 3.22 s in force control. In position control the overshoot decreased from 333 to 20.3 per cent and the settling time was reduced from 21.5 to 2.56 s. Microscale precision force and position control capabilities of the IPMC actuator were also demonstrated experimentally. An 8 μN force resolution was achieved with a force noise of 0.5μN r.m.s., and the position resolution was 6 μm with a position noise of 2.5 μm r.m.s. The maximum force and tip displacement achieved with the IPMC actuator under closed-loop control were 2 mN and 5 mm respectively. The IPMC actuator could follow various commanded force and position trajectories such as sinusoidal and trapezoidal position profiles, and a velocity profile with a 3 mm/s maximum velocity. A novel hybrid force and position control strategy demonstrated its utility in practical micromanipulalion applications where the actuator force must be limited to prevent damaging micro-objects. High-precision control of the IPMC at low force level proved its potential for micromanufacturing and micromanipulation applications such as robotic and biomedical microgrippers.