Vibration Feedback Research Articles

Study on the Mechanism of the Abnormal Phenomenon of Rail Corrugation in the Curve Interval of a Mountain City Metro

An abnormal phenomenal of rail corrugation was found in the transition and circular curve interval of the mountain city metro, in which the rail corrugation on the outer rail is more serious and earlier than that on the inner rail, and the wavelengths are also different. In the present article, the frictional self-excited oscillation of the wheel–rail system and the feedback vibration of the rail corrugation are considered comprehensively to study the mechanism of rail corrugation. According to the dynamic analysis of the vehicle track system on the high-incidence section of rail corrugation, finite element models of wheelset–track systems on the smooth track and wear track are established. Then, the unstable vibration mode and dynamic response of the wheelset–track system are calculated by complex eigenvalue analysis and transient dynamic analysis. The consistency of the numerical simulation and field test indicates that the generation of rail corrugation may be affected by the frictional self-excited vibration of the wheelset–track system. Furthermore, the feedback vibration induced by the previous rail corrugation not only aggravates the original rail corrugation but also induces new rail corrugation.

Experimental Evaluation on the Effect of Electrode Configuration in Electrostatic Actuators for Increasing Vibrotactile Feedback Intensity

Vibrotactile feedback is a key feature of many modern touch displays, which greatly enhances user experiences when interacting with an onscreen interface. Despite its popularity in small touch screen devices, this haptic feature is absent in most large displays due to a lack of suitable actuators for such applications. Thus, a growing need exists for haptic actuators capable of producing sufficient vibrations in large touch displays. This study proposes and evaluates a novel electrostatic resonant actuator (ERA) with a moving mass and dual electrodes for increased vibration feedback intensity. The dual-electrode ERA was fabricated along with a comparable single-electrode ERA to investigate the effect of the electrode configuration on the maximum vibration intensity. When measured directly on the mass, the maximum vibration intensity of the dual-electrode actuator increased by 73% compared to the single-electrode actuator. When mounted and measured on a mock panel, the maximum vibration intensity of the dual-electrode actuator increased by nearly 65% compared to a similarly mounted single-electrode actuator. These results show that the dual-electrode configuration can significantly increase the vibration intensity when compared to the conventional ERA. This demonstrates a promising potential for the use of the proposed actuator for generating vibrotactile feedback in large touch displays.

Multimodal interaction design and application in augmented reality for chemical experiment

BackgroundAugmented reality classrooms have become an interesting research topic in the field of education, but there are some limitations. Firstly, most researchers use cards to operate experiments, and a large number of cards cause difficulty and inconvenience for users. Secondly, most users conduct experiments only in the visual modal, and such single-modal interaction greatly reduces the users' real sense of interaction. In order to solve these problems, we propose the Multimodal Interaction Algorithm based on Augmented Reality (ARGEV), which is based on visual and tactile feedback in Augmented Reality. In addition, we design a Virtual and Real Fusion Interactive Tool Suite (VRFITS) with gesture recognition and intelligent equipment. MethodsThe ARGVE method fuses gesture, intelligent equipment, and virtual models. We use a gesture recognition model trained by a convolutional neural network to recognize the gestures in AR, and to trigger a vibration feedback after a recognizing a fivefinger grasp gesture. We establish a coordinate mapping relationship between real hands and the virtual model to achieve the fusion of gestures and the virtual model. ResultsThe average accuracy rate of gesture recognition was 99.04%. We verify and apply VRFITS in the Augmented Reality Chemistry Lab (ARCL), and the overall operation load of ARCL is thus reduced by 29.42%, in comparison to traditional simulation virtual experiments. ConclusionsWe achieve real-time fusion of the gesture, virtual model, and intelligent equipment in ARCL. Compared with the NOBOOK virtual simulation experiment, ARCL improves the users' real sense of operation and interaction efficiency.

An electromyogram-based tapping gesture model with differentiated vibration feedback by low-fidelity actuators

Among other aspects like attention and focus, the effectiveness of actions, such as training in percussion, also relies on the correct gesture and strength of the individual carrying out the activity repetitively to develop proper muscle memory and train motor skills. To make this process economical and efficient, we propose a system that models the feature of direction and strength of a tap and receives the corresponding active haptic feedback in an immersive virtual environment. We propose a novel tapping gesture model that takes electromyogram and vibration feedback into consideration. We also propose an approach of designing vibration modes that follow the mechanical stimulation principles and generate distinguishable vibration feedback with low-fidelity actuators. We developed a prototype using myoelectric and haptic apparatus (Myo armband and HTC VIVE controllers) and evaluated our system by conducting a user study with 50 participants. The evaluation shows that the users can distinguish three common materials (wood, rubber, and aluminum), and our system allows them to actively adjust their direction and strength to grasp the correct point while tapping. We demonstrate the efficacy of our tapping model on a virtual Chinese chimes application and observe positive feedback from both novices and expert users.

A Haptic-Based Perception-Empathy Biofeedback System with Vibration Transition: Verifying the Attention Amount.

In this paper, a perception-empathy biofeedback (PEBF) system is proposed that supplements the foot pressure status of a paralyzed foot with a wearable vibrotactile biofeedback (BF) vest to the back. Improvements in the ankle dorsiflexion and push-off movement in the swing phase and pre-swing phase, respectively, can be expected after using the proposed system. However, the results of the 3 week pilot clinical tests suggest that significant improvement is only observed for the push-off movement. It is assumed that the attention required to recognize the BF was beyond the ability of the patients. In this paper, a dual task (40 s walking and performing mental arithmetic at the same time) was conducted with the following conditions: no vibrations and providing BF to the lower back and the entire back. According to the results, the ankle joint angle of the paralyzed side at push-off under the entire back condition is statistically significant (p = 0.0780); however, there are no significant changes under the lower back condition (p = 0.4998). Moreover, the ankle joint angle of the paralyzed side at the initial contact is statistically significant with respect to the lower back condition (p = 0.0233) and shows a significant trend for the entire back condition (p = 0.0730). The results suggest that the limited attention capacity of hemiplegic patients fails to improve both dorsiflexion and push-off movements; moreover, ankle motion can be promoted if attention is concentrated on recognizing focalized vibratory feedback patterns.

Development of haptic gloves with vibration feedback as a tool for manipulation in virtual reality based on bend sensors and absolute orientation sensors

In the article, the existing developments of haptic gloves were considered, an analysis of scientific publications on this topic, which showed a variety of technical solutions. The main problems of the study area are indicated and two methods for the implementation of haptic gloves, which have a lower cost in comparison with analogues, are proposed. The first method uses nine axial sensors of absolute orientation, which allow to accurately determine the position of the joint in space, and the second method uses bend sensors, which are easier to use but less accurate. To implement the haptic gloves, software was developed, a model was created in the Unity cross-platform development environment.

Active vibration isolation system based on the LADRC algorithm for atom interferometry

A new, to the best of our knowledge, method based on the linear active disturbance rejection control (LADRC) algorithm is proposed to design and build a vertical vibration isolator below ${0.1}\;{\rm Hz}$0.1Hz for cold-atom interferometry. This system combines the control system that is used to process and to reduce feedback vibrations measured by a seismometer and a voice coil that is used to cancel the motion of a commercial passive vibration isolation platform. When the feedback is on, the vertical vibration is reduced by an additional factor of up to 1000 from 0.1 to ${5}\;{\rm Hz}$5Hz, while the system has a steady oscillation with a natural period of 66 s. The experimental results show that the LADRC is an effective control algorithm for this application and performs better than the classic lag compensation filters in our case. In addition, there are fewer parameters to adjust in this method, and we only need to tune the feedback gain of the system state error for its application.

A Hybrid Haptic Feedback Stimulation Device to Recover the Missing Sensation of the Upper Limb Amputees

Providing sensory feedback for prostheses users increases the manipulation ability, as well as introduces a feeling of the embodiment. A novel hybrid haptic feedback stimulation system of the amputees of upper limb mutilation was designed, developed, and evaluated in this study. The haptic wearable device was built by mean of single servomotor as a pressure feedback display and a pair of vibration motors as a vibration feedback display. Accordingly, the pressure display is responsible for conveying the missing sensing of the contact pressure and its force level. While the vibration display has utilized to provide an indication about the continued contact pressure. Able-body participants are engaged to evaluate the performance of the proposed feedback stimulation system. The results show that the participants are able to distinguish the touch, the start of touch, the end of touch, and the range of force with 100 % accuracy. While 96 % and 88 % of the able-body participants are capable to identify the grasp and the slipping objects, respectively. Furthermore, the ability of the proposed haptic wearable device to convey the tactile sensory information to the user’s brain without confusing or pre-training was improved.

Design and Characterization of an Actuated Drill Mockup for Orthopedic Surgical Training.

Haptic feedback in virtual reality-based trainers for surgical bone drilling is mostly provided via impedance-controlled haptic devices. Due to this, the displayable maximum stiffness is limited. In addition, vibration feedback is often only of reduced fidelity. To overcome these shortcomings, we have developed a hand-held, actuated admittance-controlled drill mockup, comprising enhanced kinesthetic and tactile feedback. This article reports on design and characterization of the device, and highlights its use for training. Kinesthetic feedback is provided through haptic augmentation, employing a ball-screw mechanism acting on a retractable drill-bit. Feedback computation relies on admittance control, thus allowing for stable display of very high resistance forces, and thus material stiffness, which cannot be achieved with standard impedance-control approaches. For the tactile mechanism, a modified linear vibration actuator is directly attached to the mockup handle, improving signal transmission. Tactile feedback computation is based on an extension of a previously proposed power spectral density control method. Frequency-specific gains are adjusted in real-time, compensating for differences between desired and measured vibrations. The performance of the device is characterized in several experiments, including comparisons to drilling with a real drill into artificial bone samples. In addition, several user studies have been carried out. We illustrate the capability of the mockup to render bone samples with different material layer stiffness and thickness. Moreover, we show that the mockup system allows for the same training effect as when rehearsing with a real drill.

A Thermal and Vibrational Feedback Glove Based on the Tactile Characteristics of Human Hand Skin

As an important method for humans to perceive their environment, touch has not been fully integrated into virtual reality technology. Existing tactile feedback devices have the problem of being large and expensive, and most studies have not explored the ability of the affected area to distinguish an external stimulus, thus it is difficult to perform natural human-computer interactions. This article describes the development of a device that can transmit multimodal tactile information in accordance with the characteristics of human hand skin perception during a human-computer interaction. The device has 10 miniature vibrators ( $\Phi =10$ mm, d=2.7 mm) and 2 semiconductor refrigerators (23 mm $\times23$ mm $\times4$ mm), which can achieve temperature and vibration feedback. First, the structure and working principle of the device were introduced, and the device’s performance was analyzed. Subsequently, an experiment based on the perception characteristics of human hand skin was designed. The experiment determined the vibration level (1-5), heating level (I-IV), and cooling level (I-III) that are consistent with the perception characteristics of the hand skin. Finally, a chemical experiment was designed to test the performance of the device. The results of the experiment showed that 92% of the volunteers thought the device had a higher sense of authenticity and immersion than the traditional virtual reality experience.

Controlled Tactile and Vibration Feedback Embedded in a Smart Knee Brace

The vastus medialis oblique (VMO) and vastus lateralis (VL) muscles at the knee joint play important roles for coordination, stability, and posture control. However, no currently available device records muscle activity while simultaneously warning users regarding abnormal muscle activity. This study used a commercialized electromyography sensors placed on the VL and VMO to monitor muscle activity while triggering warnings and vibration feedback to the muscles when an undesired ratio of VL/VMO muscular activation level set by current study was detected. The system was able to trigger alarms when the subject performed moderate-intensity activity and avoid triggering during low-intensity activity. Further research is needed of high-intensity exercises, such as running or weightlifting, to determine the effects of increased muscle activity on the judgment of the undesired ratio of VL/VMO muscular activation level using the device reported in the current study.

Hybrid Framework for Haptic Texture Modeling and Rendering

We present a hybrid framework for the modeling and rendering of both homogeneous and inhomogeneous textures with high realism by combining force and vibration feedback. Given a real texture sample, we first capture a force-feedback model using photometric stereo, which is one of the most accurate algorithms for 3D surface reconstruction in computer vision. This method allows us to model the micro-geometry of the surface and represent it by a two-dimensional (2D) height map in a very high resolution to the order of 10$\mu \text{m}$ . We also provide a new force rendering algorithm adequate for such an accurate and fine texture model. By a user study, we verify that the proposed force modeling and rendering algorithms are suitable for our hybrid texture framework. Second, we model the homogeneous and stationary vibrational characteristics of the real texture sample using the prevalent LPC (linear predictive coding)-based method. Third, we merge the force and vibration feedback models appropriately into a hybrid framework on the basis of their spectral characteristics. Last, another user study that assessed the perceived similarity between real textures and their virtual simulations demonstrates that our hybrid framework can achieve a high level of realism. To our knowledge, our framework is unique in that it can model inhomogeneous (in additional to homogeneous) real textures and render them in a virtual environment with high realism by providing both force and vibrational sensory cues.

Edge Vibration Improves Ability to Discriminate Roughness Difference of Adjoining Areas.

Researchers have studied the discrimination thresholds between different vibrotactile signals under various conditions. Humans cannot recognize slight differences in vibrotactile stimuli that are smaller than the perception threshold. This is a constraint in the vibrotactile design used in practical applications. This article focuses on the vibrational feedback at the "edge" between multiple areas, while previous studies have not considered this. We assume that the edge vibration not only emphasizes the presence of the edge itself, but also has an effect on the vibrotactile perception of the adjoining areas. Specifically, we hypothesize that the edge vibration would modify the user's ability to discriminate vibrotactile differences between adjoining areas. We conducted a user study to test this hypothesis. As a result, we found that presenting edge vibrations at the boundaries between adjacent textures makes it easier to discriminate the frequency and amplitude differences of the vibrations of those uneven textures. This article could increase the flexibility of vibrotactile design, and vibrotactile designers could use these results to design a wider variety of vibrations for adjacent areas.

Examining the Effect of Haptic Factors for Vascular Palpation Skill Assessment Using an Affordable Simulator.

Goal: Simulators that incorporate haptic feedback for clinical skills training are increasingly used in medical education. This study addresses the neglected aspect of rendering simulated feedback for vascular palpation skills training by systematically examining the effect of haptic factors on performance. Methods: A simulator-based approach to examine palpation skill is presented. Novice participants with and without minimal previous palpation training performed a palpation task on a simulator that rendered controlled vibratory feedback under various conditions. Results: Five objective metrics were employed to analyze participants’ performance that yielded key findings in quantifying palpation performance. Participants’ palpation accuracy was influenced by all three haptic factors, ranging from moderate to statistically significant. Duration, Total Path Length and Ratio of Correct Movement also demonstrated utility for quantifying performance. Conclusions: We demonstrate that our affordable simulator is capable of rendering controlled haptic feedback suitable for skills training. Further, metrics presented in this study can be used for structured palpation skills assessment and training, potentially improving healthcare delivery.

Direct writing of PVDF piezoelectric film based on near electric field added by [Emim]BF4

PVDF/IL piezoelectric film based on [Emim]BF4-added was prepared by near electric field direct writing. The β-phase content and its electric property of the film were analyzed. The results showed that the content of β crystal phase of PVDF film was improved by the synergistic effect of IL ([Emim]BF4) and near electric field. When the amount of [Emim]BF4 added was 1.5 wt%, the relative β-phase content of PVDF film reached 85.09%, and the crystallinity is 47.84%. Increase in [Emim]BF4 content resulted in a significant increase in the relative dielectric constant of the film, from 6 to 285, but also accompanied by a sharp increase in dielectric loss. The d33 value of the film can be as high as −10 pC/N, and the output voltage from the cantilever beam vibration feedback indicates that the voltage strength of the [Emim]BF4-added film is greatly improved compared with the pure PVDF film.

Perceptually Correct Haptic Rendering in Mid-Air Using Ultrasound Phased Array

This paper provides a perceptually transparent rendering algorithm for an ultrasound-based mid-air haptic device. In a series of experiments, we derive a systematic mapping function relating from the device command value to final user's perceived magnitude of a mid-air vibration feedback. The algorithm is designed for the ultrasonic mid-air haptic interface that is capable of displaying vibro-tactile feedback at a certain focal point in mid-air through ultrasound phased array technique. The perceived magnitude at the focal point is dependent on input parameters, such as input command intensity, modulation frequency, and position of the focal point in the work-space. This algorithm automatically tunes these parameters to ensure that the desired perceived output at the user's hand is precisely controlled. Through a series of experiments, the effect of the aforementioned parameters on the physical output pressure are mapped, and the effect of this output pressure to the final perceived magnitude is formulated, resulting in the mapping from the different parameters to the perceived magnitude. Finally, the overall transparent rendering algorithm was evaluated, showing better perceptual quality than rendering with simple intensity command.

The Interaction Between Feedback Type and Learning in Routine Grasping With Myoelectric Prostheses.

While prosthetic fitting after upper-limb loss allows for restoration of motor functions, it deprives the amputee of tactile sensations that are essential for grasp control in able-bodied subjects. Therefore, it is commonly assumed that restoring the force feedback would improve the control of prosthesis grasping force. However, the literature regarding the benefit of feedback is controversial. Here, we investigated how the type of feedback affects learning and steady-state performance of routine grasping with a prosthesis. The experimental task was to grasp an object using a prosthesis and generate a low or high target-force range (TFR), both initially unknown, in three feedback conditions: basic auditory feedback on task outcome, and additional visual or vibratory feedback on the force magnitude. The results demonstrated that the performance was rather good and stable for the low TFR, whereas it was substantially worse for the high TFR with a pronounced training effect. Surprisingly, learning curve and steady-state performance did not depend on the feedback condition. Hence, in the specific context of routing grasping with a prosthesis controlled via surface EMG, the basic feedback on task outcome was not outperformed by force-related end-of-trial feedback and hence seemed to be sufficient for accomplishing the task.This conclusion applies to the context of routine grasping using a myoelectric prosthesis with surface EMG electrodes, which means that the control signals are variable and the feedback is perceived and processed at the end of the trial (motor adaption).

Simulation and experiment on tonal vibration transmission control with a multi-channel global control method

A multi-channel global control method is proposed in combination with active isolators to suppress tonal vibration transmission in structures. This method is built on a modified adaptive control algorithm and the mutual interferences in control channels are compensated. The efficacy of the global control method is investigated by using a mechanical system, which consists of a hull structure, a controllable vibration source and four active mounts. A dynamic model of the mechanical system is established and the results of numerical simulation indicate that the global control method is more effective as the channel interferences are compensated and the convergence rate of it is faster than the local control method, which considers the local vibration feedback only. Experimental results also demonstrate that the global control method is able to suppress tonal vibration transmission effectively, even in the circumstance of strong mutual interferences in control channels.

Effects of Vibrotactile Feedback on Sedentary Behaviors in Adults: A Pilot Randomized Controlled Trial.

No effective and easily implemented intervention strategies for reducing sedentary behavior have been established. This pilot trial (UMIN000024372) investigated whether vibrotactile feedback reduces sedentary behavior. Twenty-six adults aged 30–69 years who were sedentary ≥8 h/day were randomly assigned to control (n = 13) or vibration (n = 13) groups. Participants wore a monitor 9 h daily for seven-day periods at baseline (week zero), during the intervention (weeks one, three, five, and seven), and after the intervention (week eight). During the eight-week intervention, vibration-group participants were notified by a vibration through the monitor whenever continuous sedentary time reached ≥30 min; they also received weekly reports of their sedentary patterns. Control-group participants did not receive feedback. The primary outcome was change in total sedentary time. Changes in longer bouts of sedentary time (≥35 min) were also assessed. No significant difference was found in the change in total sedentary time (control: −17.5 min/9 h, vibration: −9.1 min/9 h; p = 0.42). Although no significant differences were observed in sedentary time in longer bouts, vibration-group participants exhibited significantly lower sedentary time (–21.6 min/9 h, p = 0.045). Thus, vibration feedback does not appear to offer any advantages in reducing total sedentary time.

Optimized under-actuated control of blade vibration system under wind uncertainty

This paper studies the problem of optimal under-actuated control of blade vibration system (BVS) under wind uncertainty. The nonlinear BVS model is established to reveal limit cycle oscillations in flapwise, edgewise and torsional vibration motions. The difficulty of under-actuated vibration control of BVS lies in manipulating multiple degree of freedom (DOF) motions by single pitch input, and wind uncertainty could further threaten vibration reductions. A novel partial state feedback vibration control scheme is proposed based on modified linear quadratic regulator and linearized BVS. To deal with wind uncertainty, the problem of designing optimal vibration controller is converted into the problem of parameters optimization. A combined correlated differential evolutionary (CC-DE) algorithm is designed to ensure efficient optimization solution. Simulation results show that proposed method has significantly improved vibration reductions in multiple DOF motions, enhanced efficiency in actuator utilization and good performance under diverse wind uncertainties, compared to other conventional methods.