Wearable haptic feedback device for adjusting physical surface perceived roughness in real-time simulation of mixed reality environment

Abstract

The invention provides a wearable tactile feedback adjusting device used for simulating material surface texture characteristics in real time in a mixed reality environment. The invention relates to a method. The device comprises a U-shaped pneumatic actuator surrounding the fingertip of a user, a fingerstall support for accommodating the fingertip of the user, a resonance actuator located on the fingerstall support and capable of generating vibrotactile feedback to enhance the perceived roughness when the user touches the surface of an object, and a pneumatic control system that can generate a pneumatic drive command to reduce roughness perception when touching the surface of the object. Notably, the fingertip and the finger pulp of the user can still directly touch the surface of the object and cannot be blocked by the U-shaped pneumatic actuator, so that the real texture simulation experience is realized.

Description

Cross-reference to related applications:

[0001] This application claims priority to U.S. patent application serial number 18 / 581,360, filed on February 19, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0002] The present invention relates to the field of visual simulation, and more particularly to techniques for adjusting tactile feedback in mixed reality simulation. Background Art

[0003] Understanding the textural properties of material surfaces (such as roughness, hardness, and temperature) is fundamental to human interaction with the physical world. While human skin can directly perceive these properties through touch, recreating these tactile sensations in virtual reality (VR) and mixed reality (MR) remains a challenge. Therefore, a variety of haptic devices and skin-integrated interfaces are being actively developed to enable users to interact with virtual objects and experience their tactile properties. Roughness is a key factor in real-world texture perception and is typically simulated through vibrotactile stimulation on the user's hand; however, implementing these VR-centric vibrotactile stimuli in a mixed reality environment is more challenging. In mixed reality, physical objects can be used as tactile proxies for interaction to enhance user experience and work performance.

[0004] While matching virtual and physical shapes can be achieved through digital manufacturing (e.g., 3D printing), creating fine surface textures (e.g., varying roughness) on physical proxies with the same shape but different surface textures as the virtual object is inefficient. For example, 3D printing multiple physical proxies of virtual screws with the same size but different thread pitches is cost-ineffective. Given the reusability of physical tactile proxies, it would be beneficial to be able to use one or fewer physical objects to support the tactile experience of multiple virtual objects with the same physical size but different surface textures. While texture perception can be altered by applying vibrotactile stimulation directly to the physical proxies, this approach requires mounting a vibrator on the physical proxies, limiting the scalability and wearability of tactile interfaces (e.g., the work on wearable tactile devices by Pacchierotti et al.). Therefore, being able to enhance or modify the tactile texture of physical objects through wearable tactile interfaces is crucial for mixed reality interactions.

[0005] In the past, attempts to enhance the tactile experience of virtual objects have been made by using wearable devices to alter the perceived tactile sensation of physical objects. Vibrotactile feedback is a common method, often used to enhance the perceived roughness. For example, Asano et al. used a ring-shaped tactile device to introduce vibrations of varying frequencies into physical materials, thereby enhancing the perception of roughness. Furthermore, electrotactile stimulation has also been shown to enhance the perceived roughness of physical surfaces without requiring direct fingertip contact.

[0006] Currently, most research on adjusting tactile roughness through wearable devices focuses on how to enhance roughness. Although reducing the perception of roughness is an equally important aspect of adjusting roughness, there are fewer related studies and it is more difficult to do so. For example, Asano et al. applied high-frequency vibration tactile stimulation to the user's finger before the user touched the surface. The high-frequency vibration reduced the sensitivity of the skin's tactile receptors, thereby suppressing the skin's perception of surface stimuli and reducing the perceived roughness of the physical material surface. In other words, Asano et al. induced tactile fatigue by pre-intervention of the skin's stimulus reception, thereby reducing further perceived roughness. However, this method requires the introduction of additional tactile stimulation before the user actually interacts with the surface of the object, which may result in an intrusive interactive experience.

[0007] Another potential solution for modulating roughness is ultrasonic vibrations, particularly for reducing the tactile sensation of raised textures on physical surfaces. However, existing methods require ultrasonic transducers to be mounted on the material sample, limiting the scalability and wearability of tactile interfaces.

[0008] Therefore, in order to achieve the goal of simultaneously increasing and decreasing the perceived roughness of a physical surface to simulate the texture characteristics of a material surface in real-time collaboration with mixed reality or virtual reality devices, the art still needs relevant collaborative tactile devices, and the present invention is precisely to meet this need. Summary of the Invention

[0009] The purpose of the present invention is to provide a device, system or method to solve the above technical problems.

[0010] According to a first aspect of the present invention, a wearable tactile feedback adjustment device for simulating the surface texture characteristics of a material in real time in a mixed reality environment is provided. The wearable tactile feedback adjustment device includes a U-shaped pneumatic actuator surrounding a user's fingertip; a fingertip support to accommodate the fingertip; a resonant actuator, located on the fingertip support, that can generate vibratory tactile feedback to enhance the user's perceived roughness of the surface of an object touched; and a pneumatic control system that can generate pneumatic drive instructions and is connected to the U-shaped pneumatic actuator and the resonant actuator. More specifically, the U-shaped pneumatic actuator can expose the pads of the user's fingertips, allowing the user's fingertips to directly touch the surface of an object.

[0011] According to one embodiment of the present invention, the U-shaped pneumatic actuator is inflatable to lift the user's fingertips and reduce the perceived roughness of the surface of the touched object.

[0012] According to an embodiment of the present invention, the pneumatic control system drives and inflates the U-shaped pneumatic actuator according to a pneumatic driving instruction.

[0013] According to another embodiment of the present invention, the pneumatic control system includes a microcontroller, a wireless communication module, an audio amplifier, an air pressure sensor, a motor driver, a battery, and a vacuum pump.

[0014] According to one embodiment of the present invention, the resonant actuator is electronically connected to a computer device and a camera, wherein the camera captures the user's finger touching the object, and the computer device calculates the finger movement speed to generate a vibration tactile signal and delivers it to the resonant actuator, thereby generating the vibration tactile feedback.

[0015] According to one embodiment of the present invention, the U-shaped pneumatic actuator is a multi-layer structure having an inflatable uncured cavity.

[0016] According to a second aspect of the present invention, a method for adjusting real-time perceived roughness using the aforementioned wearable tactile feedback adjustment device in collaboration with a mixed reality system is provided. Specifically, the method includes detecting a user's touch action via a camera in the mixed reality system, which serves as a trigger signal to initiate a roughness adjustment step. Notably, the roughness adjustment step involves both reducing and enhancing roughness.

[0017] According to one embodiment of the present invention, the step of reducing the roughness includes inflating the U-shaped pneumatic actuator to reduce the finger-object surface contact area.

[0018] According to an embodiment of the present invention, the step of enhancing the roughness includes providing the vibrotactile feedback via the resonant actuator.

[0019] According to a third aspect of the present invention, a mixed reality system is provided. More specifically, the system includes the wearable tactile feedback adjustment device described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Embodiments of the present invention will be described in more detail below with reference to the accompanying drawings, in which:

[0021] Figures 1A-1B A schematic diagram showing the structure of a wearable tactile feedback adjustment device according to an embodiment of the present invention is shown, wherein Figure 1A The structure of the integrated linear resonant actuator, finger sleeve support, and U-shaped pneumatic actuator is shown. Figure 1B The pneumatic control system is shown;

[0022] Figures 2A-2B A schematic diagram showing the principle of reducing the contact area by pneumatic actuation is shown, where Figure 2A Displays inactive pneumatic actuators, Figure 2B Displays activated pneumatic actuators;

[0023] Figure 3 A flow chart showing a method for preparing a U-shaped pneumatic actuator;

[0024] Figure 4 Display the operation process of the pneumatic-vibratory tactile controller;

[0025] Figure 5 Display the air pressure tracking results of the PID control system;

[0026] Figures 6A-6C Shows the finite element analysis (FEM) of a U-shaped pneumatic actuator, where Figure 6A Display simulation and experimental data, Figure 6B Shows the static deformation of a U-shaped pneumatic actuator at 6kPa. Figure 6C It shows the stress distribution at 6kPa;

[0027] Figures 7A-7C Shows the fingerprint of a participant under different positive forces, 0.75N ( Figure 7A )、1.0N( Figure 7B ) and 1.5N( Figure 7C );

[0028] Figures 8A-8C Shows the required materials and settings for the user perception experiment, including Figure 8A shows the setup of the experimental environment, Figure 8B Showcase the user interface, Figure 8C Six test materials and a baseline material are presented;

[0029] Figures 9A-9E Showing participants' perceived roughness ( Figure 9A ), flatness( Figure 9B ),temperature( Figure 9C ), stiffness( Figure 9D ) and viscosity ( Figure 9E ), where “Increased_A1,” “Increased_A2,” and “Increased_A3” represent the three amplitude levels of vibrotactile stimulation, “Decreased_B1,” “Decreased_B2,” and “Decreased_B3” represent the three levels of pneumatic actuation, and “No Stimuli” represents the case of no stimulation; and

[0030] Figure 10Displays the results of a survey about mixed reality experiences. DETAILED DESCRIPTION

[0031] In the following description, devices, systems, and / or methods for implementing real-time perceptual roughness adjustment in conjunction with mixed reality devices are listed as preferred embodiments. It will be apparent to those skilled in the art that modifications, including additions and / or substitutions, may be made without departing from the scope and spirit of the present invention. Specific details may be omitted below to avoid obscuring the present invention; however, this document is written to enable those skilled in the art to practice the technology disclosed herein without undue experimentation.

[0032] In this article, the term "haptic modulation" refers to the synthetic signals generated by haptic actuators to alter the physical tactile properties of real materials. A key feature of haptic modulation is changing the perceived roughness of a material in the real world to create the tactile sensation of a new material.

[0033] In this article, the term "roughness" refers to the human tactile perception of physical surfaces. Roughness is one of the important properties for tactile exploration and differentiation of material textures.

[0034] In this article, the term "skin contact area" refers to the contact area between the fingertips and the textured surface. Skin contact area is positively correlated with applied normal force, which in turn is positively correlated with roughness. In other words, reducing skin contact area can reduce applied normal force and, in turn, reduce perceived roughness.

[0035] In this article, the term "vibrotactile feedback" refers to the provision of vibrations to simulate surface texture during the interaction between the skin and an object. It is worth noting that when exploring texture-perceived roughness through tool-assisted techniques, the frequency and amplitude of the vibrations can be adjusted to provide different roughness experiences.

[0036] According to a first aspect of the present invention, a wearable tactile feedback adjustment device for simulating the surface texture characteristics of materials in real time in a mixed reality environment is provided. The device includes a U-shaped pneumatic actuator that comfortably surrounds the user's fingertips, providing a unique and ergonomic design; a fingertip support that creates a space around the fingertips but does not cover the fingertips to ensure that the fingertips directly contact and interact with the surface of the object. This design can enhance the realism of the tactile experience; a resonant actuator that is strategically installed on the outer surface and upper surface of the fingertip support to generate vibration tactile feedback and enhance the user's perception of the roughness of the surface of the touched object; a pneumatic control system for managing pneumatic control, which includes components such as a microcontroller, a wireless communication module, an audio amplifier, an air pressure sensor, a motor driver, a battery, and a vacuum pump. It is worth noting that the pneumatic control system is configured to generate pneumatic actuation and is connected to the U-shaped pneumatic actuator and the resonant actuator.

[0037] In addition, the wearable tactile feedback adjustment device has advanced functions to achieve precise interaction with the mixed reality environment. The resonant actuator is electrically connected to a computer device and a camera, wherein the camera captures the user's action of touching the object, and the computer device calculates the speed of the finger movement and generates a vibrotactile signal based on this and sends it to the resonant actuator, thereby enhancing the realism of the tactile feedback. In addition, the U-shaped pneumatic actuator can be inflated to lift the fingertips, thereby reducing the user's perception of the roughness of the surface of the object touched. The U-shaped pneumatic actuator is a multi-layer structure with an inflatable uncured chamber, and the pneumatic control system drives and inflates the U-shaped pneumatic actuator according to the pneumatic actuation command.

[0038] This wearable tactile feedback adjustment device uses a pneumatic actuator around the fingertips. Without blocking the skin, it reduces the perceived roughness through non-interference pneumatic actuation. Therefore, there is no need to introduce additional artificial tactile stimulation (such as vibration tactile stimulation) before touch interaction. In other words, before the user's touch action occurs, the device will not apply any artificial tactile stimulation to the user's hand or the surface to be touched to cause tactile fatigue, but will directly adjust the user's perceptual experience of the object surface.

[0039] According to a second aspect of the present invention, a method for adjusting real-time perceived roughness using the aforementioned wearable haptic feedback adjustment device in collaboration with a mixed reality system is provided. The method first detects a user's touch of an object. This action is recognized by a camera integrated into the mixed reality system. The camera detects details of the user's finger interacting with the virtual or real object, which serves as a trigger for adjusting the roughness.

[0040] This adjustment method involves both reducing and increasing roughness, providing a dynamic and diverse tactile experience. The roughness reduction aspect is primarily driven by a U-shaped pneumatic actuator. When inflated, the actuator reduces the contact area between the user's finger and the surface of the object being touched. This reduced contact area significantly reduces the perceived roughness, adding a sense of realism to the tactile feedback.

[0041] Conversely, the resonant actuator plays a key role in increasing roughness. This component precisely enhances the user's perception of the roughness of the surface they touch by providing vibrotactile feedback. The resonant actuator is electrically connected to a computer device that communicates with a camera. When the camera detects a user's touch, it calculates the speed of the finger's movement and, based on this data, generates a precise vibrotactile signal that is transmitted to the resonant actuator, providing enhanced tactile feedback aligned with the user's movements.

[0042] Therefore, this method achieves a delicate and immersive tactile experience in a mixed reality environment, allowing users to interact with virtual and real objects with higher realism and feedback.

[0043] According to a third aspect of the present invention, a mixed reality system including the above-mentioned wearable tactile feedback adjustment device is provided.

[0044] Example

[0045] Example 1: Wearable tactile feedback adjustment device

[0046] In this embodiment, a tactile feedback adjustment device worn on the index finger is provided. The device utilizes vibrotactile feedback and pneumatic feedback to enhance or reduce the user's perception of surface roughness while retaining other tactile perceptions (such as temperature, viscosity, and hardness), thereby achieving the psychological effect of adjusting roughness.

[0047] like Figure 1A and Figure 1BAs shown, the tactile feedback adjustment device 100 worn on the index finger includes a linear resonant actuator 101, a support member 102, a U-shaped pneumatic actuator 103, and a pneumatic control system 104, wherein the pneumatic control system 104 is connected to the linear resonant actuator 101 and the U-shaped pneumatic actuator 103 (not shown). The support member 102 is a 3D-printed translucent shell, and the U-shaped pneumatic actuator 103 adopts a multi-layer structure, which includes a polydimethylsiloxane (PDMS) film 1031 and a polyethylene terephthalate (PET) film 1033. The PET film is sandwiched between two silicone rubber (EcoFlex 00-30) films 1032, thereby forming an uncured inflatable chamber between the two silicone rubber films, which can be inflated by pumping different amounts of gas.

[0048] The pneumatic control system 104 includes (but is not limited to) a microcontroller, an air pressure sensor, an audio amplifier, a wireless transmission module (such as a Bluetooth module), a motor driver, a battery, and an air pump. The system uses a top-mounted camera (not shown) to detect the speed of the index finger sliding across the physical surface and generates real-time vibrotactile stimulation with varying frequencies and amplitudes to enhance the user's perception of roughness.

[0049] The U-shaped pneumatic actuator 103 is a hollow pneumatic actuator that surrounds the fingertips. When inflated, it can lift the fingertips, thereby reducing the contact area between the user's fingertips and the surface of the object, thereby reducing the user's perception of the surface roughness of the object. It is worth noting that while the U-shaped pneumatic actuator 103 surrounds the edge of the fingertips, it does not completely cover the fingertips, so the user can interact with the fingertips "freely". Therefore, the user's fingertips are exposed to the outside and can directly perceive the tactile perception of the original object surface, because the user may need to alternately interact with real and virtual objects in mixed reality.

[0050] like Figures 2A-2B As shown, the U-shaped pneumatic actuator 103 can lift the fingertips by inflation. When the U-shaped pneumatic actuator 103 is activated ( Figure 2B ), which can raise the fingertip, resulting in a contact area (A2) that is larger than that when not activated ( Figure 2A ) has decreased in contact area (A1).

[0051] Silicone can be used in the U-shaped pneumatic actuator 103 as a medium for contact with the textured surface of an object. Furthermore, a layer of polydimethylsiloxane silicone rubber is applied to the U-shaped pneumatic actuator 103 to provide scalability and facilitate subsequent assembly with the 3D-printed support housing using silicone adhesive.

[0052] A linear resonant actuator 101 is mounted on top of the support 102 to generate vibrotactile feedback to enhance perceived roughness. The concept of a virtual corrugated surface can be applied to virtual texture rendering and roughness adjustment. Specifically, the pneumatic control system 104 utilizes the linear resonant actuator 101 to generate sinusoidal vibration stimulation along the index finger direction. This provides enhanced tactile perception based on the estimated finger velocity when the user touches the textured surface. It is worth noting that humans have a poor ability to distinguish the direction of high-frequency vibrations. The driving voltage Y(t) can be calculated using the following equation: Wherein, Y(t) is the driving voltage, A is the vibration amplitude, v(t) is the speed of the finger moving on the material surface, and λ is the wavelength of the rendered virtual surface. In this embodiment, the λ value is set to a constant 1.0 mm, and the phase value is set to 0.

[0053] like Figure 4 As shown, the pneumatic-vibrotactile controller 104 operates as follows: The pneumatic control system 104 includes a miniature vacuum pump (SC3101PW, DC 3.0V, 65mA, 33.5mm x 10mm x 4mm) as an air supply. The system also includes an air pressure sensor (XGZP6847A, CFSensor) for closed-loop pneumatic control with a sampling frequency of 20Hz. The air pump is controlled by an external motor driver circuit (TB6612FNG) powered by a 3.7V, 200mAh lithium polymer battery. For vibrotactile control, a power amplifier (5W, M38) communicates with the computer via Bluetooth and drives the linear resonant actuator.

[0054] The mixed reality application software detects the user's touch and triggers the roughness adjustment process. Specifically, for roughness reduction, a microcontroller (Arduino Nano) controls the pneumatic control system to change and maintain the target air pressure within the pneumatic actuator, using a reference air pressure as the set point and the air pressure readings from the air pressure sensor as feedback. A top-view camera detects the sliding speed of the index finger. A computer generates a vibration signal based on this movement and transmits it via a power amplifier to a linear resonant actuator for vibrotactile rendering.

[0055] For example, in a mixed reality scene developed with Unity3D 2019.4.39f and C# and deployed on a HoloLens 2 device, OpenCV detects the user's hand movements and calculates the index finger's velocity, while the PyAudio library generates a vibration signal. Specifically, the OpenCV-based hand tracking algorithm acquires the position of hand landmarks at a sampling rate of 30Hz and estimates the current velocity of the index fingertip at a frequency of 3000Hz, with the top-view camera at a height of 50cm above the physical surface. The current velocity value is then converted into a driving voltage wave using a sine wave function, and the vibration signal is played as an audio sequence, driving the linear resonant actuator 101 to change the vibration frequency at a frame rate of 1000Hz. When the computer receives a control signal from the HoloLens 2 (i.e., a trigger signal indicating hand-object contact), the pneumatic control system controls the linear resonant actuator and the pneumatic system, respectively, to increase or decrease the perceived roughness of the physical material.

[0056] Example 2: Preparation of a U-shaped pneumatic actuator

[0057] Figure 3 The preparation method of the pneumatic actuator is shown in the figure. To prepare the pneumatic actuator, a transparent thermoplastic polyester (PET) film with a thickness of 40μm is first laser cut using laser cutting technology to obtain a U-shaped internal module. Next, two parts of liquid silicone rubber (EcoFlex00-30A and B) are mixed in a 1:1 ratio and stirred for about 1 minute, poured onto an iron plate, and flattened to a thickness of 400μm using a film applicator; then, it is heated and cured for about 20 minutes. After the silicone film is cured, the laser-cut U-shaped internal module is attached to the first silicone film, and the above-mentioned casting and curing process is repeated to form another layer of silicone film on top of the U-shaped internal module. In this way, an uncured chamber is formed between the two layers of silicone film, which can be inflated by different air pumping volumes.

[0058] Example 3: Air Pressure Tracking Performance Evaluation

[0059] The performance of the wearable tactile feedback adjustment device was further evaluated when the air pressure in the U-shaped pneumatic actuator was varied. Before testing, uneven deformation of the pneumatic actuator was observed when the air pressure exceeded 12 kPa. This was likely due to slightly different thicknesses in different parts of the actuator caused by uneven heat distribution during the curing process.

[0060] Therefore, the target pressure range of 0 to 12 kPa is measured in 1 kPa intervals, and a total of 12 pneumatic signals are generated. In real-time inflation and deflation, a PID control algorithm with a sampling period of 0.05 seconds is used. In order to verify the pressure tracking performance of the system, Figure 5The pneumatic control system's response to three pressures (6, 8, and 10 kPa) is shown. The mean absolute error (MAE) and maximum measurement error (MME) are calculated for the pressure proportional change phase (i.e., before reaching the target pressure) and the stabilization phase (i.e., maintaining the pressure for 5 seconds). The results show that during the proportional change phase, the mean MAE is 0.679 kPa, and the maximum measurement error is 1.233 kPa. During the stabilization phase, the mean MAE is 0.386 kPa, and the maximum measurement error is 0.990 kPa. Table 1 shows all the mean absolute errors and maximum measurement errors for each reference pressure (0-12 kPa).

[0061] Table 1. Average absolute error and maximum measurement error for different reference pressure values

[0062] Example 4: Structural stability of a U-shaped pneumatic actuator

[0063] To evaluate the deformation of the U-shaped pneumatic actuator, a 3D finite element model (FEM) was constructed using COMSOL Multiphysics 5.5 (COMSOL, Sweden) to simulate the shape change under different air pressures. The 3D model of the pneumatic actuator was remodeled and simplified to a U-shaped plate consisting of two layers of 400 μm thick stretchable silicone film (Ecoflex-30, Smooth-On, USA), and a pressure load ranging from 0 to 12 kPa was applied to the actuator. The elastic parameters of the silicone material (such as the elastic modulus) were adjusted according to the deformation response measured by the expansion distance, and a linear relationship between air pressure and height distance was obtained, as shown in Figure 2. Figure 6A shown. Figure 6B It is shown in the figure that the maximum deformation of the pneumatic actuator is evenly distributed in the middle part of the pneumatic channel, that is, the finger can be lifted smoothly. Figure 6C It is shown that during the deformation process, the pressure is distributed from the middle to the edge of the pneumatic tube, that is, the deformation direction is perpendicular to the surface of the U-shaped plate, while the stress direction is tangential to the surface of the U-shaped plate. Figures 6A-6C Experimental measurements of the lift distance of an actual pneumatic tube at different air pressures are also shown, demonstrating that the control system is able to follow the simulation well.

[0064] Example 5: Reducing the contact area of the finger surface

[0065] By elevating the fingertips, the device can significantly reduce the contact area between the user's fingertips and the textured surface of an object. For the experiment, three participants were recruited and wore the device on their index fingers. They pressed their fingertips against a paper surface with normal forces of approximately 0.75N, 1.0N, and 1.5N. The participants' fingertips were inked, and their fingerprints were collected on a dynamometer (DS2-5N, PUYAN). Three different air pressures (6kPa, 8kPa, and 10kPa) were tested to compare the fingertip contact area under different pneumatic stimulation conditions. Figures 7A-7C The fingerprint images and edge lines of one of the participants under different applied forces are shown in Figure 2.

[0066] By counting the number of pixels in each fingerprint image, the proportion of contact area with and without pneumatic stimulation was analyzed. The results showed that the proportion of contact area reduction gradually increased with increasing air pressure and decreasing normal force. Specifically, the average proportion of contact area reduction is: under a normal force of 1.5N, it is 8.1% (standard deviation = 2.15%) at 6kPa, 11.9% (standard deviation = 3.18%) at 8kPa, and 20.8% (standard deviation = 2.62%) at 10kPa; under a normal force of 1.0N, it is 8.6% (standard deviation = 4.46%) at 6kPa, 15.2% (standard deviation = 3.20%) at 8kPa, and 28.8% (standard deviation = 6.12%) at 10kPa; under a normal force of 0.75N, it is 12.8% (standard deviation = 3.67%) at 6kPa, 25.5% (standard deviation = 2.55%) at 8kPa, and 39.6% (standard deviation = 3.79%) at 10kPa.

[0067] Example 6: Detecting Delay, Noise, and Power Consumption

[0068] The reaction time of the controller was also evaluated. Figure 5As shown, the average activation time is 145.83 milliseconds (standard deviation = 39.65), and the average deactivation time is 329.17 milliseconds (standard deviation = 94.05), indicating real-time performance. Based on a Dell i5 CPU, at a 30Hz refresh rate, the vibration tactile feedback latency for hand motion tracking and velocity estimation is approximately 53.53 milliseconds (standard deviation = 8.32). To evaluate the device's noise level, a sound level meter was placed approximately 40 cm from the device, simulating the distance between the user's wrist and ear when the device is in use. The measured noise levels are as follows: approximately 51.0 dB when the control signal is 6 kPa; approximately 56.9 dB when the control signal is 8 kPa; and approximately 59.0 dB when the control signal is 10 kPa, while the ambient noise level is approximately 38.9 dB. The device is powered by a 200mAh, 3.7V lithium polymer battery (LiPo battery). Under the pneumatic driving condition of 10kPa, the maximum current is about 60mA (0.2W); it generates 6.2m / s at 250Hz. 2 When the acceleration signal is detected, the maximum power consumption of vibration feedback is about 2 W. Therefore, the maximum total power consumption of the current system is about 2.2 W, which can support about 19 minutes of continuous tactile feedback.

[0069] Example 7: User Perception Experiment on Adjusting Surface Tactile Properties Using a Wearable Tactile Feedback Adjustment Device

[0070] In the user perception experiment, the effect of the tactile adjustment device on changing the user's tactile perception of different material surfaces is analyzed. The experiment must take into account the five psychophysical dimensions of the user in tactile interaction, including roughness, flatness, temperature, viscosity and stiffness. It is worth noting that the mediation of the roughness perceived by the material surface includes the vibration cues of fine roughness (spatial period less than 200μm) and the spatial cues of flatness or macro roughness (spatial period greater than 200μm). In subjective descriptions, flatness is usually expressed as "unevenness", while fine roughness is mainly described as "roughness". The present invention assumes that the perceived roughness or unevenness of the textured surface may increase through the vibration tactile feedback of the device; while reducing the contact area between the finger and the surface and the applied positive force through pneumatic drive may reduce the perceived roughness. In addition, the experiment also analyzes whether the tactile adjustment device will have a perceptual impact on the user in other psychophysical tactile dimensions (such as temperature, viscosity and stiffness).

[0071] Twelve participants (5 women, 7 men) were recruited from a local university for this study, and the experimental protocol was approved by the university's ethics committee. All participants were right-handed and had no prior experience with tactile interfaces. Their average age was 29.1 years (SD = 3.03), and the average width of the distal interphalangeal joint (DIP) of their dominant index finger was 14.9 mm (SD = 1.33). In the power analysis, with a sample size of 12 participants, the probability of perceiving a difference in roughness across different tactile stimulation levels was 89.2% at a significance level of 0.05. The experimental protocol was approved by the university's ethics committee.

[0072] Figure 8A The experimental environment is shown in the following figure, which includes a tactile adjustment device, a device for displaying a graphical user interface ( Figure 8B ) and a tablet computer to record participant feedback. Participants wore the tactile modulation device on their dominant hand and placed their hand behind a large piece of cardboard to avoid visual bias; a reinforced arm support device was also installed on the experimental table to reduce potential fatigue during the experiment. In addition, to avoid auditory bias, participants also wore noise-isolating earmuffs. A top camera (5MP, 30fps, JERRY, China) was installed at a height of 50 cm to capture index finger movements and calculate their velocity.

[0073] In this user perception experiment, seven different materials were used, including glass plate, ceramic plate, paper, plywood, balsa wood, cowhide and cotton cloth (such as Figure 8C (as shown) to analyze how the device alters the user's tactile perception of these materials. Initially, only four materials—leather, paper, wood, and cotton—were selected for roughness / texture modulation. However, to balance the range of roughness, two smoother materials—glass and ceramic—as well as a medium-roughness plywood material were added. All of these material samples were cut to 10 cm x 10 cm, 2 mm thick, and placed on a 10 cm-high acrylic stand.

[0074] The stimulation provided by the tactile modulation device includes three types of vibrotactile stimulation, three types of pneumatic stimulation, and no stimulation, for a total of seven types of stimulation. Among them, the amplitude levels of the three vibrotactile stimulations are 3.7, 4.9, and 6.2 m / s at a frequency of 250 Hz. 2The accelerations were recorded as stimuli A1, A2 and A3 respectively. When the subjects scanned the textured surface with their fingers, the higher the vibration amplitude, the higher the perceived roughness was generally. In addition, the three different air pressure levels of pneumatic drive stimulation were 6kPa, 8kPa and 10kPa, recorded as stimuli B1, B2 and B3 respectively, and the corresponding fingertip lifting distances were 2.24 mm (standard deviation = 0.121), 3.36 mm (standard deviation = 0.258) and 4.07 mm (standard deviation = 0.274) on average.

[0075] Before the experiment began, all participants were asked to rate the perceived roughness of seven material surfaces using only their fingers (1 being the smoothest and 7 being the roughest). Glass was consistently rated as the smoothest material, while over 80% of participants rated leather as the roughest. Plywood was ranked fourth in terms of roughness / smoothness among the seven materials. Therefore, plywood served as the baseline material, and the other six materials served as test materials. Briefly, participants were asked to compare their perceived roughness of each test material with the perceived roughness of the baseline material (plywood) without the device, using a tablet's graphical user interface with a rating slider positioned at the center of the baseline.

[0076] The experimental design was as follows: This experiment used a within-subjects factorial design with two independent variables: tactile stimulus type (i.e., vibrotactile, pneumatic, and no stimulus) and material type. The dependent variable was the subjective rating of the perceived intensity of the five psychophysical dimensions (roughness, flatness, temperature, stickiness, and hardness) of each test material under each tactile stimulus. In each trial, each tactile stimulus (i.e., vibrotactile or pneumatic) lasted for 5 seconds, followed by a 5-second reset period to allow the skin to return to a neutral state. However, including the subject's rating time, the actual interval between trials was approximately 20 seconds. Notably, no visual or auditory cues were provided during the stimulation. The flat screen in front of the participant displayed only a countdown. After each stimulus, five rating sliders were presented, allowing participants to move the sliders on a continuous scale from 1.00 to 100.00, with 1.00 representing the lowest level and 100.00 the highest. The initial position of the rating sliders was in the middle (i.e., 50.00 / 100.00), representing the tactile perception of the baseline material (i.e., plywood). Each participant remained seated throughout the experiment (including rest periods). Each stimulus was repeated five times, with the first one serving as a training session and no data collected. The six test materials (glass, paper, cotton, ceramic, wood, and leather) were presented in a counterbalanced Latin square order, with all stimulus signals for each material presented randomly. Ultimately, each subject completed a total of 210 trials (6 materials x 7 stimuli x 5 repetitions), with the total experimental duration not exceeding 2 hours.

[0077] The experiment, conducted by one experimenter and one subject, followed the typical "introduction-pre-questionnaire-training-testing" procedure and consisted of two phases: a training phase and an experimental phase. The training phase involved the same practical procedures as the experimental phase, but no data was recorded. At the beginning of the experiment, the experimenter briefed the subject on the experimental procedure. The subject then sat in a comfortable position and completed a pre-questionnaire containing demographic information. Before the experiment began, the subject washed their hands with soap and dried them with a towel to ensure normal tactile perception of their fingertips. The experimenter then measured the width of the distal interphalangeal joint of the subject's index finger on their dominant hand and provided them with a suitably sized 3D-printed housing for the device.

[0078] During the experiment, the subjects were required to gently slide their fingertips from one side to the other, maintaining a sliding speed between 50-200 mm / s and an applied positive force between 0.3-1.2 N to clearly perceive the texture of each textured surface. A baseline stimulus was given to the subjects after every six trials. It is worth noting that the subjects could request to touch the texture of the baseline material (plywood) at any time. Additionally, between tests on each of the two materials, the subjects were required to remove the device and take a mandatory 3-minute break. Before the test, the subjects could practice the sliding motion until they felt ready.

[0079] A two-way repeated-measures ANOVA was performed on the subjective roughness ratings of the subjects for all test materials, with stimulus type and material type as independent variables. Mauchly's sphericity test was performed first, and the results showed that the sphericity assumption was violated (p < 0.05). Therefore, a Greenhouse-Geisser correction was used to adjust the degrees of freedom. The results showed that tactile stimulation (F (1.47, 15.475) = 79.502, p < 0.0001, η 2 ρ =0.878) and material type (F(2.225, 24.477) = 64.279, p < 0.0001, η 2 ρ=0.854) had a statistically significant effect on the subjective ratings; in addition, there was no significant interaction effect between the two factors. Post hoc pairwise comparisons under different stimulation conditions for each material showed that there were significant differences in subject ratings between almost all stimulation and no stimulation conditions (p < 0.05). Overall, under vibrotactile stimulation, the material was perceived as rougher, and the roughness rating increased with increasing vibration amplitude levels; while under pneumatic stimulation, the material was perceived as flatter (i.e., the higher the air pressure, the flatter the rating). Table 2 details the results of the Bonferroni-corrected post hoc pairwise comparisons for each condition, while Table 3 shows the means and standard deviations of the subjects' subjective roughness ratings. These results show that based on psychophysical dimensions, subjects can perceive different degrees of roughness under different stimulations through the device, including modulation of increasing or decreasing roughness.

[0080] Table 2. Results of the effects of stimulus factors on the roughness and flatness of each material (the symbol “>” indicates p < 0.05 and a significant difference, and the symbol “~” indicates no significant difference).

[0081] Table 3. Mean and standard deviation of the subjective scores of subjects’ perceived roughness

[0082] Figure 9A Further descriptive results are presented for the subjects' subjective ratings of roughness perception under different stimuli and material types, demonstrating some overlap in rating ranges between stimuli and materials. For example, the boxplot range for glass under the "Enhanced A1" condition largely overlaps with the boxplot range for ceramic under the "No Stimulation" condition, while the range for paper under the "No Stimulation" condition also overlaps to some extent with the boxplot range for wood under the "Reduced B1" condition. This demonstrates that the device provides a wide range of tactile stimulation, capable of adjusting the perceived roughness of one material to approach that of another. For example, using the device of the present invention, the perceived roughness of wood under pneumatic stimulation can be reduced to a level close to that of paper, while increasing the roughness can bring the perceived roughness of glass closer to that of ceramic.

[0083] In addition to roughness, participants’ perception of other tactile attributes such as flatness, temperature, viscosity, and stiffness was also investigated. Figure 9B Descriptive results of the subjects’ subjective ratings of smoothness are shown, and their trends are consistent with those of the roughness ratings ( Figure 9A ). Then, the results of the two-way repeated measures variance analysis on the subjects' flatness scores showed that the material type (F(1.969, 21.656) = 29.399, p < 0.0001, η2 ρ =0.728) and stimulus type (F(1.231, 13.538)=29.160, p<0.0001, η 2 ρ =0.726) had a significant impact on the scores. In addition, based on Pearson correlation analysis, it was found that there was a strong correlation between perceived roughness and flatness scores (r(420)=0.882, p<0.001).

[0084] At temperature (F(5,55)=31.424, p<0.0001, η 2 ρ =0.741), viscosity (F(1.596, 17.558)=10.811, p<0.0001, η 2 ρ =0.496) and stiffness (F(1.955, 21.510) = 31.119, p < 0.0001, η 2 ρ =0.739), there were significant differences between different material types. However, there were significant differences between different tactile stimuli in temperature (F(6,66)=1.304, p=0.268, η a ρ =0.106), stiffness (F(6,66)=2.163, p=0.058, η 2 ρ =0.164) and viscosity (F(6,66)=0.493, p=0.811, η 2 ρ =0.043) showed no significant difference, see Figures 9A to 9C The above comparison results show that the device of the present invention does not significantly change (or can maintain) the tactile properties of the material surface such as temperature, viscosity and stiffness.

[0085] In summary, after analyzing the device's ability to control the perceived roughness of six materials, including glass, ceramics, paper, wood, leather, and cotton, the results show that the vibrotactile stimulation generated by the device can enhance the perceived roughness of the object material. In particular, for relatively flat materials such as glass and ceramics, higher vibration amplitudes can exhibit a more significant effect of enhancing the roughness. In addition, the device lifts the fingertips through pneumatic action and reduces their contact area with the material surface, thereby reducing the perceived roughness. A larger lifting displacement (i.e., a higher air pressure level) results in a lower roughness score. Possible mechanisms include: 1) The reduction in contact area reduces the normal force applied to the textured surface, thereby reducing the perceived roughness; 2) Due to the smaller skin contact area, the number of tactile mechanoreceptors contained is smaller, so the overall perceptual activity is reduced, and the activity of tactile mechanoreceptors is positively correlated with roughness perception. These two mechanisms may work together to reduce the perceived roughness.

[0086] In addition, the device can also affect the perceived flatness of the material (i.e., macro-roughness). According to research by Okamoto et al., due to the significant overlap between perceptual mechanisms and psychological models, it is difficult for humans to distinguish between the two dimensions / concepts of micro-roughness and macro-roughness (i.e., flatness). A similar phenomenon was observed in this experiment, where some subjects were confused about the two attributes. The experimental results showed that the flatness and roughness perceived by the subjects had similar trends, indicating that these two dimensions jointly affect the perception of the textured surface. It is worth noting that all subjects agreed that the device significantly reduced the perceived flatness of uneven materials such as cow-grain leather, which can be attributed to the reduction in contact area, which reduced the normal force acting on the leather surface, thereby reducing the sensitivity to spatial patterns related to macro-roughness.

[0087] Furthermore, the device had no significant effect on the other three material properties (i.e., temperature, viscosity, and stiffness), suggesting that it may be able to maintain the original perceptual states of these properties during tactile interaction with surfaces. While previous research has suggested that reducing the applied normal force and contact area may reduce viscosity or enhance the sensation of coolness when in contact with textured surfaces, no statistically significant changes were observed in the present invention.

[0088] The reason for the lack of change in viscosity perception may be that the subjects perceived the friction between the silicone tube and the material surface, which masked the change in viscosity perception caused by the reduction in contact area. In addition, the subjects were asked to maintain a normal pressure in the range of 0.3-1.2N when sliding, resulting in a smaller actual contact area between the fingertip skin and the material. Therefore, such a small range of force and contact area changes may not be enough to cause the perception of significant temperature changes. Previous studies on changes in perceived temperature have mainly focused on cases with larger contact areas (e.g., more than 10cm). 2 ). In addition, the subjects were not asked to actively press on the textured surface to perceive stiffness, which may explain why no significant changes in perceived stiffness were observed and why stiffness perception was related to the rate of change of stress, but the applied force was relatively stable in the relevant experiments.

[0089] Example 8: Analysis of the Impact of Wearable Haptic Feedback Adjustment Device on User Experience in Mixed Reality Environments

[0090] A mixed reality scene was created using Unity3D (2019.3.4.39f), integrating the hand tracking functionality of the HoloLens 2 and a 5-megapixel camera for finger velocity estimation and device operation. The mixed reality scene contained six real-world objects: a wooden board, two cups (one glass and one ceramic), two table mats (one cotton and one leather), and a cardboard box (as shown in Table 4). To ensure visual and tactile consistency, the virtual objects matched the dimensions of these real-world objects but were constructed from different virtual materials. Specifically, the virtual glass / ceramic cups corresponded to the real-world ceramic / glass cups, respectively; the virtual leather / cotton table mats corresponded to the real-world cotton / leather table mats; the virtual wooden cube corresponded to the real-world paper cube, and virtual paper was displayed on the wooden table surface (application scenarios are shown in Table 4). Interactive operators were divided into two modes: 1) using only their fingers (BareFinger); and 2) wearing the device and using corresponding tactile feedback (ViboPneumo).

[0091] There were 10 subjects (5 females and 5 males) with an average age of 29.3 years (standard deviation 2.75 years). All subjects were right-handed and had never participated in similar experiments (one of them had experience using mixed reality applications but had not used tactile devices). The average width of the distal interphalangeal joint of the index finger of the subjects was 15.7mm (standard deviation 1.73rmrmm). Power analysis showed that when the sample size was 5 and the significance level was 0.05, the probability of perceiving the difference between the two operation modes at different tactile stimulation levels was 96.1%.

[0092] Based on the results of the user perception experiment in Example 7, a tactile stimulation scheme for roughness adjustment was selected, which is basically as follows: Increasing roughness: Vibrotactile stimulation was applied to a glass cup (corresponding to a virtual ceramic cup), a paper cube (corresponding to a virtual wooden cube), and a cotton table mat (corresponding to a virtual leather table mat). Roughness reduction: Pneumatic tactile stimulation was applied to a ceramic cup (corresponding to a virtual glass), a wooden board (corresponding to a virtual paper), and a leather table mat (corresponding to a virtual cotton table mat). Based on the results of Example 7 and taking into account the flatness perception, energy-saving parameters were further designed for the tactile stimulation intensity, as shown in Table 4.

[0093] Table 4. Mixed reality application scenarios and tactile stimulation parameters used

[0094] Each experiment involves one subject and one experimenter. The experimenter will introduce the experiment and process to the subject and assist him / her in wearing the HoloLens 2 headset and the adapted tactile adjustment device; the subject will then receive guidance from the experimenter and learn how to use the tactile adjustment device to interact with objects in a mixed reality environment. The experiment includes two sub-tests of mixed reality interaction: the finger mode (BareFinger) and the vibration pneumatic mode (ViboPneumo). In the vibration pneumatic mode, the subject touches and feels the surface texture of various virtual objects through the tactile feedback generated by the tactile adjustment device, where the tactile feedback is adjusted based on the surface characteristics of the real object. The order in which each subject performs the two mode tests is counterbalanced.

[0095] At the end of each subtest, participants completed a custom questionnaire based on the Presence Questionnaire and the System Usability Scale. Using a 7-point Likert scale (1: Strongly Disagree - 7: Strongly Agree), the questionnaire focused on the visual and tactile experience of mixed reality. Following the experiment, a semi-structured interview was conducted to gather participants' qualitative feedback on the device and its potential applications.

[0096] Figure 10 The results of the two interaction modes were compared, with the operation mode as the independent variable and the questionnaire responses as the dependent variable. The results were analyzed using the Wilcoxon signed-rank test. The results showed that the operation mode had a significant effect on the following questionnaire items: consistency between visual and tactile information (Z = -2.816, p = 0.005), consistency of tactile sensations in mixed reality and the real world (Z = -2.816, p = 0.005), naturalness of texture perception (Z = -2.814, p = 0.005), and user preference (Z = 2.388, p = 0.017). However, no significant differences were found between the two modes on the following questionnaire items: ability to actively explore or search the mixed reality environment (Z = -0.378, ρ = 0.705) and usability (Z = -0.816, p = 0.414). This indicates that the tactile modulation device of the present invention does not restrict users' ability to explore the mixed reality environment and is easy to use for novice users.

[0097] Regarding qualitative feedback, the first question the subjects asked was how to distinguish different objects in the same category (such as glass cups and ceramic cups). All subjects mentioned that they could visually distinguish different placemats in mixed reality, but it was difficult to distinguish different cups due to the overlap between virtual objects and real objects; however, the use of the device can provide different roughness on these materials, thereby enhancing the experience of distinguishing between ceramic cups and glass cups. P3 said: "With a reasonable tactile experience, I can distinguish between the two different cups through texture interaction, but when I touch them directly with my fingers, the visual and tactile experiences are extremely mismatched, which makes me feel very uncomfortable." Regarding the feeling of the virtual wooden box superimposed on the paper box, all subjects agreed that the device of the present invention can make the paper box with a wooden appearance really present the tactile feeling of wood texture.

[0098] Afterward, participants were encouraged to explore possible application scenarios for the device. P8 (a participant with MR experience) commented: "I think it would be a useful tool for designers. Some designers use augmented reality to show different looks for customized / personalized products (e.g., clothing), and this system can not only change the look but also provide corresponding tactile feedback on the fabric." Another participant (P5) suggested that the device could be used for game control. For example, through the device, users could control the movement of a virtual character on the surface of a real material while simultaneously feeling a modified roughness to create a matching experience (e.g., when the virtual character walks on virtual ice, the roughness can be reduced).

[0099] In summary, changing the sense of roughness through this device improves the visual-tactile matching experience and enhances the object perception experience in mixed reality. In a mixed reality environment, augmented reality allows virtual objects to exist in a real environment, and users expect the tactile experience of virtual objects to be consistent with their visual appearance. By using real objects as tactile proxies for virtual objects, it is particularly important for users to be able to feel a consistent visual-tactile experience in mixed reality. The device of the present invention can provide a diverse tactile texture experience in mixed reality by changing the perceived roughness while retaining other material properties of the existing object. For example, the user can not only feel the original texture of a ceramic cup, but also adjust the roughness of the ceramic cup to a texture similar to glass or metal in mixed reality through this device. In addition, the device has multiple potential application scenarios: Immersive gaming: Enhance the user's interactive experience through tactile feedback. Museum experience: Users can wear the device and feel the enhanced roughness on the surface of the glass display case through vibrotactile stimulation, thereby "touching" the texture of ancient pottery inside the display case. Design Assist: The device helps designers evaluate 3D-printed prototypes, modify the roughness or switch the material of a specific part without requiring additional production steps. Tactile Design Tool: This device can be used to customize the perceived roughness of physical materials, benefiting material design.

[0100] In summary, the present invention provides a wearable tactile adjustment device that changes the perceived roughness of real objects in mixed reality through vibrotactile and pneumatic feedback. The device uses a linear resonant actuator to increase the sense of roughness through vibrotactile stimulation. On the other hand, a hollow pneumatic actuator is used to reduce the contact area between the fingertips and the surface of the real object to reduce the sense of roughness. In user perception experiments, the results showed that the device can effectively change the perceived roughness of certain materials. In addition, the subjects' ratings of roughness overlapped between certain materials, indicating that it has the potential to adjust the perception of one material to that of another. User research on mixed reality experience showed that changing the perceived roughness of real materials through the device significantly improved the user's visual-tactile matching experience in mixed reality.

[0101] In certain embodiments, the device can be applied to a variety of potential scenarios. For example, a user could wear the device to explore the surface textures of museum artifacts (such as ancient pottery) within a glass display case, or select materials and customize products in mixed reality while retaining the freedom of the fingertips for unrestricted texture exploration. Applications of the device include (but are not limited to) fields such as art, media, film and television, culture, and heritage preservation.

[0102] According to embodiments of the present invention, the functional units and modules of the devices, systems, and / or methods may be implemented by computer devices, computer processors, or electronic circuits, including but not limited to application-specific integrated circuits, field programmable gate arrays, microcontrollers, and other programmable logic devices, which may be configured or programmed according to the teachings of the present invention. Based on the disclosure of the present invention, a person skilled in the art of software or electronics can easily write computer instructions or software codes for execution on a computing device, computer processor, or programmable logic device.

[0103] Depending on the embodiment, all or part of the method may be executed in one or more computer devices, including server computers, personal computers, laptop computers, and mobile computing devices such as smartphones and tablet computers.

[0104] Embodiments may also include computer storage media, or transient and non-transitory storage devices storing computer instructions or software codes that can be used to program or configure a computer device, computer processor, or electronic circuit to perform any of the processes of the present invention. Such storage media or storage devices may include, but are not limited to, floppy disks, optical disks, Blu-ray disks, DVDs, CD-ROMs, and magneto-optical disks, as well as ROMs, RAMs, flash memory devices, or any other medium or device suitable for storing instructions, codes, and / or data.

[0105] The foregoing description has been presented to illustrate and describe the present invention, but is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations will be apparent to those skilled in the art.

[0106] The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, thereby enabling others skilled in the art to understand the invention for various embodiments and with various modifications as are suited to the particular use contemplated.

Claims

1. A wearable tactile feedback adjustment device for real-time simulation of material surface texture characteristics in a mixed reality environment, characterized in that: include: a U-shaped pneumatic actuator that wraps around the user's fingertips; a fingertip support to accommodate the user's fingertips; a resonant actuator located on the finger cuff support, capable of generating vibrotactile feedback to enhance the user's perceived roughness when touching an object's surface; and a pneumatic control system, which can generate pneumatic drive instructions and is connected to the U-shaped pneumatic actuator and the resonant actuator; The U-shaped pneumatic actuator can expose the fingertips of the user, so that the fingertips of the user can directly touch the surface of the object.

2. The wearable tactile feedback adjustment device according to claim 1, wherein the U-shaped pneumatic actuator can be inflated to lift the user's fingertips and reduce the perceived roughness of the surface of the object being touched.

3. The wearable tactile feedback adjustment device according to claim 2, wherein the pneumatic control system drives and inflates the U-shaped pneumatic actuator according to the pneumatic drive instruction.

4. The wearable tactile feedback adjustment device according to claim 1, wherein the pneumatic control system comprises a microcontroller, a wireless communication module, an audio amplifier, an air pressure sensor, a motor driver, a battery and a vacuum pump.

5. The wearable tactile feedback adjustment device according to claim 1, wherein the resonant actuator is electronically connected to a computer device and a camera, wherein the camera captures the touching action of the user's finger, and the computer device calculates the finger movement speed to generate a vibrotactile signal and delivers it to the resonant actuator, thereby generating the vibrotactile feedback.

6. The wearable tactile feedback adjustment device according to claim 1, wherein the U-shaped pneumatic actuator is a multi-layer structure having an inflatable uncured chamber.

7. A method for adjusting real-time perceived roughness by using the wearable tactile feedback adjustment device according to claim 1 in collaboration with a mixed reality system, characterized in that: include: The camera in the mixed reality system detects the user's touch action as a trigger signal to start the roughness adjustment step; The roughness adjustment step includes reducing the roughness and enhancing the roughness.

8. The method of claim 7, wherein reducing the roughness comprises inflating the U-shaped pneumatic actuator to reduce the finger-object surface contact area.

9. The method of claim 7, wherein said enhancing roughness comprises providing said vibrotactile feedback via said resonant actuator.

10. A mixed reality system, characterized in that: Comprising a wearable tactile feedback adjustment device according to claim 1.

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