Paper-based contact members, devices, and systems for active mechanical haptics

Abstract

The present application relates to a paper-folding based contact member, apparatus and system for active mechanical haptics. The paper-folding based contact member for active mechanical haptics comprises a top plate, a bottom plate, and at least one curved paper-folding based metamaterial disposed between the top plate and the bottom plate, with its top end fixed on the top plate and its bottom end fixed on the bottom plate, wherein the top plate is exposed to be contacted by a body part of a user, and wherein the curved paper-folding based metamaterial comprises a panel having a single curved crease extending along a longitudinal direction thereof, the single curved crease dividing the panel into two faces at opposite sides thereof. The panel is configured to be folded along the single curved crease to form a folding angle between the two faces. The folding angle is configured to be adjusted by rotating the bottom plate so as to achieve a variable stiffness covering a positive stiffness to a negative stiffness that will be perceived by the body part of the user via contact with the top plate when loaded along a vertical axis between the top plate and the bottom plate.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to origami-based contact members, devices and systems for active mechanical haptics. BACKGROUND

[0002] The emerging meta-universe driven by virtual reality (VR) and augmented reality (AR) technologies is transforming the current digital media of third-person perspective into the future immersive platform that vividly presents the physical environment perceived by the first-person perspective. This is achieved by building virtual environments with real sensory perceptions, including but not limited to vision, hearing, and haptics. In this new paradigm of how humans interact with future media, VR / AR technologies are ready to penetrate into a range of industry fields (e.g., entertainment, communication, education, human-computer interaction, teleoperation, clinical treatment, and rehabilitation), while enhancing our VR / AR, haptic experiences with advanced software (i.e., communication technologies, various applications, and social networks) and hardware (i.e., VR / AR and haptic devices). Although the latest VR / AR devices of technologies provide stereoscopic visual and auditory sensory perceptions, they cannot deliver the specific sensory dimension (i.e., haptics) in the mechanical field. In fact, haptics is very different from our vision and hearing, which are passive because we humans receive information in the third person. Substantial progress has been made in making the virtual world tactile by bringing passive haptic experiences to users; however, most of them produce simple, hand-centric motion constraints or vibrations (vibro-haptics). This is in stark contrast to how humans perceive the physical environment of the hardness, softness, and even the breaking moment of a fragile object through active touch by the hands, feet, or other body parts. On the other hand, haptics is primarily active, and human-triggered mechanical sensory perception is considered one of the most indispensable human senses for interacting with the physical world. Therefore, it is promising to reproduce in the virtual world controlled active mechanical haptics that allow users to actively generate and perceive mechanical haptics with controllable stiffness ranging from hard to soft and from positive to negative. SUMMARY

[0003] The present disclosure is provided to solve the above problems existing in the prior art, i.e., to provide origami-based contact members and haptic devices for active mechanical haptics, immersive VR / AR systems for providing active mechanical haptics, and corresponding sensory perceptions, thereby allowing users to actively generate and perceive mechanical haptics with controllable stiffness ranging from hard to soft and from positive to negative. The origami-based contact members, haptic devices, and immersive VR / AR systems aim to generate human-triggered mechanical sensory perceptions and enhance VR / AR experiences beyond vision, hearing, or passive haptics, while providing a range of diverse immersive experiences.

[0004] According to one aspect of the present disclosure, a paper-folding based contact member for active mechanical haptics comprises: a top plate; a bottom plate; and at least one curved paper-folding based metamaterial disposed between the top plate and the bottom plate, with its top end fixed on the top plate and its bottom end fixed on the bottom plate, the top plate being exposed to be contacted by a body part of a user; wherein the curved paper-folding based metamaterial comprises a panel having a single curved crease extending along a longitudinal direction thereof, the single curved crease dividing the panel into two faces on opposite sides thereof, the panel being configured to be folded along the single curved crease to form a folding angle between the two faces; the folding angle being configured to be adjusted by rotating the bottom plate so as to achieve a variable stiffness covering a positive stiffness to a negative stiffness when loaded along a vertical axis between the top plate and the bottom plate, the variable stiffness to be perceived by the body part of the user via contact with the top plate.

[0005] In another aspect of the present disclosure, a haptic handheld device for providing active mechanical haptics is provided, the device comprising: five paper-folding based contact members according to any embodiment of the present disclosure, the body part of the user being a finger or a thumb; an actuation mechanism and a control portion, wherein the control portion is configured to: communicate with a VR / AR engine so as to receive a stiffness adjustment command indicative of a current stiffness of a virtual object in a VR / AR scene when tracking an active grasping operation of the virtual object by the user; and control the actuation mechanism in response to the stiffness adjustment command so as to rotate the shaft of the bottom plate to adjust the stiffness to be perceived by the finger / thumb of the user; and a support shell for housing the five paper-folding based contact members, the actuation mechanism and the control portion, the support shell being provided with five openings for exposing the top plates outside.

[0006] In another aspect of the disclosure, there is provided a paper-folding based contact member for active mechanical haptics, the contact member comprising: a top plate exposed to be contacted by a body part of a user; a bottom plate; a plurality of curved paper folding based metamaterials disposed between the top plate and the bottom plate and arranged into a plurality of rows; and a cable provided corresponding to the rows such that each row has an independent cable; each of the curved paper folding based metamaterials has a top end and a bottom end, the top end being fixed on the top plate and the bottom end being fixed on the bottom plate; each of the curved paper folding based metamaterials comprises a panel having a single curved crease extending along a longitudinal direction thereof, the single curved crease dividing the panel into two faces at opposite sides thereof, the panel being configured to be folded along the single curved crease to form a folding angle between the two faces; a first hole is formed on one of the two faces and a second hole is formed on the other of the two faces; for each row of the plurality of curved paper folding based metamaterials, the corresponding independent cable is sequentially threaded through the two holes cut out on the panel, and is knotted at a side behind each panel so as to be synchronously pulled / released to adjust the folding angle of the panel, thereby achieving a variable stiffness covering a range from positive stiffness to negative stiffness that will be perceived by the body part of the user via contact with the top plate when loaded along a vertical axis between the top plate and the bottom plate.

[0007] In another aspect of the disclosure, there is provided a haptic stepping device for providing active mechanical haptics, the device comprising: a paper-folding based contact member according to any embodiment of the disclosure, the body part of the user being a foot; and an actuation mechanism comprising a cable and a control portion, wherein the control portion is configured to: communicate with a VR / AR engine to receive a stiffness adjustment command indicative of a current stiffness of a virtual object in a VR / AR scene when tracking an active stepping operation of the user on the virtual object; and control the actuation mechanism in response to the stiffness adjustment command to synchronously pull / release the cable to adjust the stiffness to be perceived by the foot of the user.

[0008] In another aspect of the disclosure, there is provided an immersive VR / AR system for providing active mechanical haptics, the system comprising: a haptic handheld device for providing active mechanical haptics according to any embodiment of the disclosure and / or a haptic foot-tread device for providing active mechanical haptics according to any embodiment of the disclosure as a haptic assembly; and a VR / AR engine configured to: communicate with both a VR / AR device and the haptic device; send stiffness adjustment commands indicative of a current stiffness of a virtual object in a VR / AR scene to the haptic assembly upon tracking active grasping and / or active treading operations of the virtual object by a user; and send a stream related to the VR / AR scene to the VR / AR device. The immersive VR / AR system further comprises the VR / AR device configured to: communicate with the VR / AR engine to receive the stream related to the VR / AR scene and present the VR / AR scene to the user accordingly; and track the active grasping and / or active treading operations of the virtual object by the user in the VR / AR scene.

[0009] In another aspect of the disclosure, there is provided a paper-folding based contact member for active mechanical haptics, comprising: a top plate; a bottom plate; and at least one curved paper-folding based metamaterial disposed between the top plate and the bottom plate, wherein the curved paper-folding based metamaterial comprises panels, and a variable stiffness of the curved paper-folding based metamaterial is achieved by twisting the panels or by pulling / releasing the panels through connecting members passing through the panels; wherein the variable stiffness encompasses a range from positive stiffness to negative stiffness.

[0010] Further details and aspects of exemplary embodiments of the disclosure are described in more detail below in connection with the accompanying drawings.

[0011] The paper-folding based contact member and the haptic device for active mechanical haptics according to the disclosure can achieve active mechanical haptics encompassing positive stiffness (feeling hard and soft) and negative stiffness (feeling broken and falling instantaneously), which are considered to be the core and part of the first sensory perception in human daily interaction with the physical environment for exploring / processing information and creating ontological metaphors. In addition, the immersive VR / AR system for providing active mechanical haptics according to the disclosure can obtain the combination of visual, auditory and active touch sensory perceptions in AR / VR haptic experiences, thereby providing exciting potential for expanding the reality of the virtual world.

[0012] The above general description and the following detailed description are merely exemplary and illustrative, and are not intended to limit the disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0013] In the drawings, which are not necessarily drawn to scale, like numerals can describe similar components in different views. Like numerals having different letter suffixes can represent different instances of the components. The drawings illustrate generally, by way of example, various embodiments discussed in the specification and are not intended to limit the claimed embodiments to the embodiments pictured. These embodiments are illustrative rather than limiting in nature. The drawings are intended to be illustrative rather than limiting.

[0014] FIG. 1(a) and FIG. 1(b) illustrate several exemplary active stiffness perception in a life scenario, according to embodiments of the present disclosure.

[0015] FIG. 2(a) illustrates a schematic diagram of partial composition of a paper-folding based contact member for active mechanical haptics, according to embodiments of the present disclosure.

[0016] FIG. 2(b) illustrates a schematic diagram of two symmetrically arranged paper-folding based metamaterials, according to embodiments of the present disclosure.

[0017] Figures 3(a) to 3(h) FIG. 3 illustrates a schematic diagram of partial composition of a paper-folding based metamaterial and working mechanism of its stiffness adjustment, according to embodiments of the present disclosure.

[0018] Figure 4 FIG. 4 illustrates an example diagram of a button formed by a paper-folding based contact member, according to embodiments of the present disclosure.

[0019] Figure 5 FIG. 5 illustrates the configuration of a single curved folding crease, according to embodiments of the present disclosure.

[0020] FIG. 6(a) illustrates the process of manufacturing a silver nanowire (AgNW) coating deposited substrate for a panel, according to embodiments of the present disclosure.

[0021] FIG. 6(b) illustrates the relative resistance change (AR / R0) of the sensing layer when loaded with strain at different folding angles.

[0022] FIG. 7(a) illustrates an example diagram of a user using a haptic handheld device to perceive different stiffness of various objects in a virtual environment, according to embodiments of the present disclosure.

[0023] FIG. 7(b) illustrates a schematic diagram of partial composition of a haptic handheld device, according to embodiments of the present disclosure.

[0024] FIG. 7(c) illustrates a confusion matrix showing the recognition rate of 12 participants under three different interactive methods.

[0025] Fig. 7(d) illustrates physiological signals (EMG) of the upper limbs when the user grips different real and virtual objects in three handheld conditions.

[0026] Figure 8 Fig. illustrates a schematic diagram of partial composition of the control part of the haptic handheld device according to an embodiment of the present disclosure.

[0027] Fig. 9(a) illustrates an exploded schematic diagram of the actuation mechanism of the haptic handheld device according to an embodiment of the present disclosure.

[0028] Fig. 9(b) illustrates a top view schematic diagram of the transmission system of the actuation mechanism according to an embodiment of the present disclosure.

[0029] Fig. 10(a) illustrates a schematic diagram of composition of another origami-based contact member for active mechanical haptics according to an embodiment of the present disclosure.

[0030] Fig. 10(b) illustrates a schematic diagram of a curved origami-based metamaterial of the origami-based contact member according to Fig. 10(a).

[0031] Figure 11 Fig. illustrates a schematic diagram of a stepping member formed by the origami-based contact member according to an embodiment of the present disclosure.

[0032] Figure 12 Fig. illustrates a schematic diagram of partial composition of the control part of the haptic stepping device according to an embodiment of the present disclosure.

[0033] Fig. 13(a) illustrates an exploded schematic diagram of the actuation mechanism of the haptic stepping device according to an embodiment of the present disclosure.

[0034] Figures 13(b) to 13(d) Fig. illustrates a schematic diagram of the transmission system of the actuation mechanism based on the curved origami-based metamaterial and its synchronous actuation according to an embodiment of the present disclosure.

[0035] Figure 14 Fig. illustrates a schematic diagram of partial composition of an immersive VR / AR system for providing active mechanical haptics according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0036] In order for those skilled in the art to better understand the technical solutions of the present disclosure, the present disclosure will be described in detail below in conjunction with the drawings and specific embodiments. The embodiments of the present disclosure will be described in more detail below in conjunction with the drawings and specific embodiments, but these embodiments are not intended to limit the present disclosure.

[0037] As used in the present disclosure, "first", "second", and similar terms do not denote any order, quantity, or importance, but are used only to distinguish different components. "Include" or "contain" and other similar terms mean that the elements that appear before the word encompass the elements listed after the word, but do not exclude other elements.

[0038] Furthermore, although exemplary embodiments have been described herein, the scope of the disclosure includes any and all embodiments having equivalent elements, modifications, omissions, combinations (e.g., of the scenarios associated with the various embodiments), adaptations, or alterations based on the present disclosure. The elements of the claims are to be construed in the broadest reasonable manner, and the use of the terms "have", "including", "contain", "containing", or "including" are not limiting. The elements of the claims are not to be construed as elements of means plus function or step plus function unless the element is specifically recited as "means for" or "step for". The terms "comprising", "including", "containing", "characterized by" and the like are not to be interpreted in an excluding nature specifically recited means plus function or step plus function elements are specifically recited as being "means for" or "step for". The mere fact that different features are recited in mutually different dependent claims does not indicate that the

[0039] Figures 1(a) and 1(b) illustrate several exemplary active stiffness perceptions in a life scenario, according to embodiments of the present disclosure. In Figure 1(a), an example of human-initiated hand-held stiffness perception is shown, including feeling positive stiffness when grasping elastic / rigid / soft objects, and feeling negative stiffness when crushing fragile objects, such as eggs. And, in Figure 1(b), an example of human-initiated body-centered stiffness perception is schematically illustrated, including feeling positive stiffness in the process of stepping on various grounds, and feeling negative stiffness when accidentally stepping off.

[0040] In the scenarios shown in Figures 1(a) and 1(b), when an object is grasped in the hand or stepped on the foot, people can easily distinguish the object due to its unique intrinsic property, i.e., its stiffness. When hitting a ball or stepping on grounds with different hardness, people feel positive stiffness, and the difference is reflected in the magnitude of the positive stiffness value. However, when crushing an egg or stepping off in walking, negative stiffness is experienced, resulting in a feeling of falling or even fear (the heart rate curve in Figure 1(b) shows the user's psychological response). To reconstruct these active haptics in a VR / AR environment, a paper-based contact member for active mechanical haptics, a haptic device, and an immersive VR / AR system are proposed in the present disclosure.

[0041] Figure 2(a) illustrates a schematic diagram of the partial composition of a paper-based contact member for active mechanical haptics, according to embodiments of the present disclosure.

[0042] As shown in FIG. 2(a), the origami-based contact member for active mechanical haptics includes a top plate 21, a bottom plate 22, and at least one piece of curved origami-based metamaterial 23 (with its top end 23a fixed on the top plate 21 and its bottom end 203b fixed on the bottom plate 22) in between, the top plate 21 being exposed to be contacted by a body part (not shown in FIG. 2(a)) of a user.

[0043] Figures 3(a) to 3(h) FIG. 3(a) illustrates a schematic diagram of the partial composition of the curved origami-based metamaterial 23 and its working mechanism of stiffness adjustment. In these figures, where a (the angle between the horizontal edge and the tangent at the end of the single curved crease 232) represents the normalized curvature of the single curved crease 232; a (the angle between the two curved surfaces (Surface 1 and Surface 2)) represents the plastic origami fold.

[0044] FIG. 3(a) illustrates a 2D pattern (unfolded flat) and a 3D configuration (already folded) of the curved origami-based metamaterial 23. As shown in FIG. 3(a), the curved origami-based metamaterial 23 includes a panel 231 having a single curved crease 232 extending along its longitudinal direction, which divides the panel 231 into two surfaces on its opposite sides, shown as Surface 1 and Surface 2. In addition, the panel 231 is configured to be folded along the single curved crease 232 to form a folding angle b between Surface 1 and Surface 2, and the folding angle b is configured to be adjusted by rotating the bottom plate 22 so as to achieve a variable stiffness covering from positive stiffness to negative stiffness, which will be perceived by a body part of a user through contact with the top plate 21 (see FIG. 2(a)) when loaded along a vertical axis between the top plate 21 and the bottom plate 22.

[0045] Referring to FIG. 3(a), by simply introducing the single curved crease 232, which is a circular-arc-shaped cut line characterized by an angle a, which is related to the radius p of the circle as where a x b is the geometry of the rectangular panel 231), by folding the 2D panel 231 along a single curved crease 232. The folding angle β around the single curved crease 232 is determined by the plasticity imposed by the folding process, where the greater the bending deformation of the curved origami-based metamaterial 23, the smaller β, and the smaller the bending deformation, the greater β. For the single curved crease 232, the panel 231, and the plasticity at the single curved crease 232, a variant (non-standard) Miura-ori (Fig. 3(b)) is employed to analyze and detail the mechanical performance of the curved origami, where the angle γ is related to the plastic folding angle β (i.e., γ(β)), which is then employed to predict the stiffness of the curved origami and guide the design selection. Upon the application of a vertical load on the top plate 21 (see Fig. 2(a)), the curved origami-based metamaterial 23 exhibits different force-displacement relationships depending on the competition between the bending deformation that provides positive stiffness and the folding deformation around the single curved crease 232 that provides negative stiffness. Fig. 3(c) shows the force-displacement relationship of a piece of curved origami-based metamaterial 23 defined with a = 80° and a / b = 1.25 at different folding angles β (i.e., initial states) of 60°, 90°, and 120°, where the larger β (e.g., 120°) exhibits both positive and negative ranges, and the smaller β (e.g., 60°) only produces positive stiffness. Therefore, for a given curved origami-based metamaterial 23 (i.e., angle a), its stiffness can be easily adjusted by changing the folding angle β (such as by rotating the bottom plate 22, or by a cable-driven method (Fig. 3(d)) where an external force is actively applied on the top plate 21 (e.g., by a user of an active mechanical haptics), and a cable is threaded through both faces (face 1 and face 2) to adjust the folding angle β in real-time from a specific initial value (e.g., β = 120° for a wider adjustment range) by Δβ. Unlike the plasticity in the folding process that defines the folding angle β, twisting the bottom plate 22 or pulling the cable produces an elastic folding process of the curved origami-based metamaterial 23, where the metamaterial 23 immediately recovers to its original folded state (defined by the folding angle β) after the bottom plate 22 is twisted back or the cable is released. Fig. 3(e) shows the force-displacement relationship of the curved origami-based metamaterial 23 at different adjustment angles Δβ (Δβ = 0°, 35°, and 60°), where a = 80°, β = 120°, and a / b = 1.25, exhibiting a variable stiffness that covers both positive and negative ranges when loaded along the vertical axis between the top plate 21 and the bottom plate 22, and this variable stiffness can be perceived by a user’s body part through contact with the top plate 21.

[0046] The embodiments described above establish the effectiveness of using cable-driven methods (including cable-induced torsion) to adjust the stiffness of curved origami in real time. Regarding tactile perception, different positive stiffnesses reflect levels of hardness, while negative stiffness mimics the feeling of crushing an object or dropping (or slipping). Therefore, during the active pressing of a curved origami-based metamaterial with negative stiffness using a constant force, its acceleration becomes an important metric characterizing this property. For the same curved origami-based metamaterial in Figure 3(e), the acceleration under constant load (i.e., constant force) can reach as high as 0.6G (1G in free fall) at β = 120° and Δβ = 0°, 35°, and 40°, as shown in Figure 3(f). To guide the design of metamaterials based on curved origami to achieve a more pronounced mechanical sense, Figure 3(g) provides a phase diagram of the normalized secant stiffness as a function of the crease angle α (30° < α < 85°) and the adjustment angle Δβ, where the initial fold angle β = 120° is specified, representing the actual angle when the cable is pulled, ranging from 0° to 120°. To utilize the most significant stiffness sense, only the largest negative stiffness is selected when the origami has both positive and negative stiffness ranges. When the origami has only a positive stiffness range, the largest positive stiffness is used. From a practical perspective, the angle α is a predetermined parameter because it defines the metamaterial style based on curved origami. For example, to obtain both positive and negative stiffness simultaneously, the crease angle is set in the range of 55° to 85°, and the fold angle is adjusted between 30° and 130°.

[0047] Therefore, this phase diagram provides a design (by angle α) and operating guide (by adjusting angle Δβ) for obtaining a sensory perception of stiffness using a surface-origination-based metamaterial. Similar to the elastic deformation during plate rotation or cable pulling, the deformation during cyclic pressing of the top plate of the surface-origination-based metamaterial is also elastic (Fig. 3(h)), where negative and positive stiffness can be clearly seen in each cycle.

[0048] In some embodiments, at least one origami-based metamaterial comprises two (e.g., a pair) origami-based metamaterials. As shown in FIG2(b), there are two origami-based metamaterials (i.e., origami-based metamaterial 23 and origami-based metamaterial 23'), wherein one origami-based metamaterial is axially symmetrical with the other origami-based metamaterial along axis 31, thereby providing a more stable structure when used to construct a haptic device.

[0049] In some embodiments, the origami-based contact member according to embodiments of this disclosure is formed as a button. For example... Figure 4As shown, each of the five buttons (i.e., button 41, button 42, button 43, button 44, and button 45) is formed by a paper-based contact member according to an embodiment of the present disclosure. Furthermore, taking button 44 as an example, the base plate 442 is circular and has a shaft 442a, which can be rotated by an actuation mechanism 46.

[0050] In some embodiments, Figure 4 A single curved surface crease in a paper-based contact component can have Figure 5 The structure shown. (As illustrated) Figure 5 As shown, the single curved surface crease 50 is constructed from the following parts: two end extensions (i.e., end extensions 51a and 51b), a middle extension 51c, and two arc-shaped cutting grooves (i.e., arc-shaped cutting grooves 52a and 52b), each cutting groove connecting its adjacent end extension and middle extension.

[0051] In some embodiments (e.g.) Figure 4 or Figure 5 In the origami-based contact component, the panel can be made of a substrate with a sensing layer deposited thereon, which is used to sense the applied strain and change its electrical properties. Figure 6(a) illustrates the process of manufacturing a substrate with a silver nanowire (AgNW) coating deposited as a sensing layer on the substrate of the panel. Specifically, in step S61, a substrate and an AgNW suspension are prepared. In step S62, the AgNW suspension is coated (applied) onto the surface of the substrate. Then, in step S63, the suspension is dried in an oven for 6 hours to obtain the AgNW-coated substrate. In some embodiments, the applied strain of the panel can be represented by the change in height, and the electrical properties of the sensing layer can be represented, for example, by the change in relative resistance (ΔR / R0), so the relationship between the sensed applied strain and the electrical properties of the sensing layer is shown in Figure 6(b).

[0052] Figure 6(b) shows the change in relative resistance (ΔR / R0) of the sensing layer when the top plate of the origami-based contact member is cyclically and actively pressed at different folding angles (i.e., β-Δβ, where β = 120°, Δβ = 0°, 30°, 60°, and 90°). The characteristic of the change in electrical properties can be observed from Figure 6(b): the change in relative resistance (ΔR / R0) is positively correlated with the applied strain.

[0053] According to embodiments of the present disclosure, a haptic handheld device for providing active mechanical tactile feedback is also provided. Figure 7(a) shows an example diagram of a user using the haptic handheld device to perceive different stiffnesses of various objects in a virtual environment according to an embodiment of the present disclosure. As shown in Figure 7(b), the haptic handheld device 700 includes five origami-based contact members according to the present disclosure (origami-based contact members 71a-71e as shown in Figure 7(b)), and the user's body part is a finger or thumb (for actively grasping the origami-based contact members of the haptic handheld device 700, as shown in Figure 7(a)).

[0054] In some embodiments, the haptic handheld device 700 may include an actuation mechanism (not shown) and a control unit (not shown). Specifically, the control unit is configured to communicate with a VR / AR engine (not shown in FIG. 7(b)) to receive a stiffness adjustment command indicative of the current stiffness of a virtual object corresponding to the haptic handheld device 700 while tracking active grasping actions performed by a user on a virtual object in a VR / AR scene. The control unit is also configured to control the actuation mechanism in response to the stiffness adjustment command to rotate the axis of the base plate of the origami-based contact members 71a-71e forming buttons to adjust the stiffness perceived by the user's fingers / thumbs. Furthermore, the haptic handheld device 700 includes a support housing 74 for accommodating five origami-based contact members, the actuation mechanism, and the control unit, the support housing 74 having five openings for exposing the top plates of the origami-based contact members.

[0055] As shown in Figure 7(b), the support shell 74 is spherical in shape and has five slots 741 for accommodating five origami-based contact members 71a-71e respectively. Each slot 741 is provided with a sliding guide 741a for limiting the compression range (e.g., 10 mm) of the corresponding origami-based contact member.

[0056] In addition, five origami-based contact members can be installed in the support shell 74 according to common human gripping postures, with the origami-based contact member 71e for the thumb located on the support shell 74 on the side opposite to the other four fingers.

[0057] like Figure 8 As shown, the control unit of the haptic handheld device 700 according to an embodiment of the present disclosure may further include a microcontroller 731, a sampling resistor module 732, and a wireless communication interface 733. In some embodiments, the sensing layer is configured to change its resistance (e.g., when strain is applied by a user's finger or thumb to the top plate of the origami-based contact member) when pressure / release operations are performed. Figure 8In some other embodiments, the sampling resistor module 732 is coupled to the sensing layer and converts the changed resistance R thereof into a voltage change.

[0058] In some other embodiments, the microcontroller 731 is coupled to the sampling resistor module 732 and forwards the voltage change to the VR / AR engine 75 via the wireless communication interface 733, so that the VR / AR engine 75 subsequently converts the voltage change into a deformation of the virtual object and changes the corresponding VR / AR scene that the user will see through the VR / AR device 76. In addition, a power supply 77 (such as a 5V small battery) can be integrated into the support shell 74 to achieve wireless control.

[0059] FIG. 9(a) illustrates an exploded schematic diagram of an actuation mechanism of a haptic handheld device according to embodiments of the present disclosure. In some other embodiments, the control portion of the haptic handheld device 700 can further include a motor driving module 734, and accordingly, the actuation mechanism further includes a motor 721 and a transmission system 722, as shown in FIG. 9(a) and FIG. 9(b).

[0060] Figure 8 The microcontroller 731 in the sensing layer can also be configured to receive a stiffness adjustment command from the VR / AR engine 75 indicating the changed stiffness of the virtual object (not shown) if the deformation of the virtual object causes a change in its current stiffness, and send a driving command to the motor driving module 734 in response to the stiffness adjustment command. In addition, the motor driving module 734 can also be configured to start the motor 721 to transmit rotation to the shaft of the bottom plate of the haptic handheld device through the transmission system 722, so as to adjust the stiffness that will be perceived by the user's fingers / thumb. In some embodiments, the change in the current stiffness of the virtual object can include being crushed or falling off from the virtual object.

[0061] In some other embodiments, the microcontroller 731 can also be configured to determine the amount of rotation of the motor 721 according to the changed stiffness of the virtual object indicated in the stiffness adjustment command; and generate a driving command for the motor driving module 734 to make the motor 721 rotate at the determined amount of rotation.

[0062] Fig. 9(b) shows a top view of a schematic diagram of a transmission system of an actuation mechanism according to an embodiment of the present disclosure. As shown in Fig. 9(b), the motor 721 can include a drive shaft 721a, the transmission system 722 can include a worm 722a mounted and fixed to the drive shaft 721a of the motor 721, a spool 722b threadedly connected with the worm 722a, at least four rollers 722c each having an axis parallel to the axis of the spool 722b and perpendicular to the axes of the drive shaft 721a and the worm 722a, and connected with the bottom plate of the five origami-based contact members 71a-71e via at least four universal joints 722d, and a cable 722e; the cable 722e is wound around the spool 722b and the at least four rollers 722c in sequence, such that the worm 722a can rotate and transmit rotation to the spool 722b as the drive shaft 721a rotates, the spool 722b rotates the cable 722e to rotate the at least four rollers 722c, thereby synchronously transmitting rotation to the bottom plate of the five origami-based contact members 71a-71e. The universal joints can be used to transmit rotation between the top plate and the bottom plate of the curved origami-based contact members around a vertical axis.

[0063] In some other embodiments, the transmission system 722 can include four rollers 722c, and in order to save space, the origami-based contact member for the thumb 71e and the origami-based contact member for the middle finger (such as 71b) are connected with the same roller 722c. In this way, the rotation of the bottom plate of the five button-shaped origami-based contact members can be synchronously controlled by one motor 721 to implement a cable-wiring-based SI-MO (Single Input Multiple Output) actuation strategy, thereby achieving a more compact and lightweight structure. In Fig. 9(b), the thick arrow represents the driving of the spool 722b, and the thin arrow represents the following rolling of the multiple rollers 722c.

[0064] In some other embodiments, the transmission system 722 can further include a tensioning roller 722f, and the portion of the cable 722e between the spool 722b and the four rollers 722c is pulled tight by the tensioning roller 722f. The tensioning roller 722f can be used to pre-tension the cable 722e to avoid slippage between the cable 722e and the multiple rollers 722c.

[0065] In addition, due to the self-locking property of the worm, the structure of the haptic handheld device 700 can withstand the torque of the relative rotation between the top plate and the bottom plate of the curved origami-based contact member and maintain a state of prescribed rigidity, thereby achieving a more energy-efficient system.

[0066] The haptic handheld device 700 of similar objects can provide human-triggered active mechanical haptics (with stiffness perception covering both positive and negative ranges). The microcontroller 731 of the haptic handheld device 700 connects the virtual environment and the actual perception, and achieves the effect of “what the user sees is what the user feels” by synchronously providing various stiffness perceptions based on the virtual objects seen, and guiding changes (not limited to shape) in these virtual objects in the virtual environment based on active user inputs made by pressing the button. For example, for a soft sphere in the virtual environment, the user can feel its softness, and feel its deformation and see its deformed appearance when actively pressed.

[0067] There are various scenarios in which the user grasps various virtual objects (e.g., elastic spheres vs. crushable spheres, soft spheres vs. rigid spheres), and perceives their respective stiffnesses through the haptic handheld device 700. The two-way connection between the user and the virtual objects by the haptic handheld device 700 makes the objects in the virtual environment perceptible to the user, and in turn deformable in the virtual world. This perception is triggered by the user’s active grasping, which is similar to interacting with real objects in the physical environment, thereby providing a better immersive experience.

[0068] To evaluate the haptic perception imparted by the haptic handheld device according to the present disclosure, 12 participants were recruited to identify 4 different spherical objects with different mechanical properties (i.e., “rigid” with high stiffness, “elastic” with relatively lower stiffness, “soft” with the lowest stiffness, and “crushable” with negative stiffness) in three different ways: 1) virtual environment with only visual information (i.e., only VR glasses); 2) active touch only (i.e., only the haptic device of the present disclosure); and 3) combined information of vision and touch (VR glasses + the haptic device of the present disclosure). Fig. 7(c) shows the confusion matrix for the three cases, where the columns and rows correspond to the preset properties and the properties identified by the participants. As expected, the participants could not determine the mechanical properties of the virtual objects with only visual information from the VR glasses. The highest identification rate was below 77%, and notably, the highest identification rate was below 22% when identifying two similar objects (i.e., the “elastic” object and the “soft” object). In contrast, when using only the haptic device of the present disclosure, the identification rate was almost 100%, indicating that the device can replicate the stiffness information. Interestingly, when the participants used the haptic handheld device in conjunction with visual information from the VR glasses, the identification rate decreased (i.e., the identification rate was higher than 91% for the “rigid” and “crushable” objects; while the identification rate was slightly higher than 80% for the “elastic” and “soft” objects), which can indicate that, in terms of stiffness perception, touch is in a more important position than visual information, as the latter is unreliable and sometimes even misleading.

[0069] To more objectively assess haptic perception, physiological signals (i.e., electromyography or EMG) of electrical activity from the muscles were recorded when users attempted to grasp four objects with different stiffnesses using four different modalities (one in the physical environment and three in the virtual environment). In the physical environment, four spheres (rigid wooden sphere, buckled plastic sphere, high-pressure elastic soccer ball #1, and low-pressure soft soccer ball #1) were used as benchmarks for evaluation. In the virtual environment, three grasping modalities were presented when the VR glasses visually presented four spheres (rigid sphere, breakable sphere, elastic sphere, and soft sphere): 1) using the haptic handheld device of the present disclosure; 2) using gestures only without touching anything in the real physical world; and 3) using a joystick (a currently common interaction tool). Fig. 7(d) shows the RMS (root mean square) values of the EMG signals when grasping various objects (real objects in the physical world or virtual objects in the VR world) under different handheld conditions. The results clearly show that the trend presented by the haptic handheld device of the present disclosure is very similar to that based on real objects (i.e., higher stiffness excites higher EMG voltage), and the crushing motion tends to quickly reduce the value. In contrast, for the cases of gestures only and joystick, these values are indistinguishable, thus lacking real haptic perception from the muscle point of view. Statistical analysis further shows that the haptic handheld device of the present disclosure exhibits significant performance (P < 0.001 in most cases) in simulating different mechanical stiffnesses when compared with real objects, providing distinguishable stiffness perception, while gestures and traditional joysticks produce statistically insignificant perception (P > 0.05) for users.

[0070] According to one embodiment of the present disclosure, another origami-based contact member for active mechanical haptics is also provided. Fig. 10(a) illustrates a schematic diagram of the composition of another origami-based contact member for active mechanical haptics according to an embodiment of the present disclosure. Referring to Fig. 10(a), the origami-based contact member 1000 can include: a top plate 1010 exposed to be contacted by a body part of a user; a bottom plate 1020; a plurality of curved origami-based metamaterials 1030 arranged in multiple rows between the top plate and the bottom plate; and a cable 1040 corresponding to the rows, such that each row has an independent cable 1040. Each of the curved origami-based metamaterials 1030 has a top end 1030a and a bottom end 1030b, the top end 1030a can be fixed on the top plate 1010, and the bottom end 1030b can be fixed on the bottom plate 1020.

[0071] Fig. 10(b) illustrates a schematic view of a curved-fold-based metamaterial of a paper-folding-based contact member 1000. As shown in Fig. 10(b), each piece of the curved-fold-based metamaterial 1030 includes a panel 1031 having a single curved fold 1031a extending along its longitudinal direction, which divides the panel 1031 into two faces (face 1 and face 2) at its opposite sides, and the panel 1031 is configured to be folded along the single curved fold 1031a to form a folding angle between face 1 and face 2. In addition, a first hole 1031b is formed on one of the two faces (e.g., face 1), and a second hole 1031c is formed on the other of the two faces (e.g., face 2). Furthermore, for each row of the curved-fold-based metamaterial 1030, a corresponding independent cable 1040 is sequentially threaded through the two holes cut on the panel, which is knotted at one side behind each panel 1031, so that when loaded between the top plate and the bottom plate along the vertical axis, the cables are synchronously pulled / released to adjust the folding angle of the panel, thereby achieving a variable stiffness covering from positive stiffness to negative stiffness, which will be perceived by the user’s body part through contact with the top plate 1010.

[0072] Specifically, as shown in Fig. 10(a), the paper-folding-based contact member 1000 can be formed as a tread member, and the body part is a foot. Figure 11

[0073] Similar to the paper-folding-based contact member shown in Fig. 2(a), the single curved fold 1031a of the paper-folding-based contact member 1000 is composed of two end extensions, a middle extension, and two circular-arc-shaped cut grooves, each of which connects its adjacent end extension and middle extension.

[0074] As shown in Fig. 10(a), the paper-folding-based contact member 1000 can further include a plurality of pairs of loops and columns, the columns being fixed and distributed on the bottom plate 1020 at the periphery of the plurality of pieces of the curved-fold-based metamaterial 1030, and the loops being fixed on the bottom side of the top plate 1010 corresponding to the columns, so that each loop is slidably sleeved on the corresponding column.

[0075] The plurality of pairs of loops and columns can be used to restrict the movement of the tread member (such as the tread member in Fig. 10(a)) of the haptic platform in the vertical direction only when the user actively treads. Figure 11 In addition, the sliding range between the loops and the columns is preset to limit the depression range of the paper-folding-based contact member 1000.

[0076] The paper-folding-based contact member 1000 can further include a distance sensor (not shown) arranged between the top plate 1010 and the bottom plate 1020 to detect the displacement of the top plate 1010 in the vertical direction. For example, the distance sensor can be arranged on the bottom plate 1020.​

[0077] In addition, as shown in FIG. 10(a) and FIG. 10(b), each cable 1040 is independent of each other and has a free end 1041 extending out of the proximal panel to be pulled / released independently.

[0078] According to one embodiment of the present disclosure, there is provided a haptic treading device for providing active mechanical haptics. As shown in FIG. 12, the haptic treading device 1200 for providing active mechanical haptics can include the origami-based contact member 1210 shown in FIG. 10(a), FIG. 10(b) or FIG. 10(c), and in particular, the body part of the user is a foot. Figure 12 Figure 11 As shown in FIG. 12, the haptic treading device 1200 for providing active mechanical haptics can include the origami-based contact member 1210 shown in FIG. 10(a), FIG. 10(b) or FIG. 10(c), and in particular, the body part of the user is a foot.

[0079] In some other embodiments, the haptic treading device 1200 can further include an actuation mechanism 1220 including cables 1221 and a control section 1230. The control section 1230 can be configured to communicate with a VR / AR engine 1240 to receive a stiffness adjustment command indicative of a current stiffness of a virtual object in a VR / AR scene when tracking active treading operations of the user on the virtual object, and to control the actuation mechanism 1220 in response to the stiffness adjustment command to synchronously pull / release the cables 1221 to adjust the stiffness to be perceived by the foot of the user.

[0080] In some other embodiments, the control section 1230 can further include a microcontroller 1231, a distance sensing module 1232, and a wireless communication interface 1233. The distance sensing module 1232 can be configured to convert a sensed distance change caused by active treading of the foot of the user on the top plate into a voltage change, and the microcontroller 1231 can be coupled to the distance sensing module 1232 and forward the voltage change to the VR / AR engine via the wireless communication interface 1233, so that the VR / AR engine can subsequently convert the voltage change into a deformation of the virtual object and change the corresponding VR / AR scene seen by the user through the VR / AR device 1250.

[0081] FIG. 13(a) illustrates an exploded schematic view of a partial composition of the actuation mechanism of the haptic treading device, and FIG. 13(b), FIG. 13(c) and FIG. 13(d) illustrate schematics of a transmission system of the actuation mechanism according to embodiments of the present disclosure. Similar to the haptic handheld device 700, the control section 1230 can further include a motor drive module (not shown), the actuation mechanism 1220 can further include a motor 1222 and a transmission system 1223 including the cables 1221 (as shown in FIG. 13(a)), and the microcontroller 1231 can be further configured to, if the deformation of the virtual object causes a change in its current stiffness, forward the voltage change to the VR / AR engine 1240 (as shown in FIG. 13(b)), and the VR / AR engine 1240 can be further configured to convert the voltage change into a corresponding change in the stiffness of the virtual object and send a stiffness adjustment command to the control section 1230 (as shown in FIG. 13(c)), and the control section 1230 can be further configured to control the motor 1222 to pull / release the cables 1221 to adjust the stiffness to be perceived by the foot of the user (as shown in FIG. 13(d)). Figure 12 ​The motor drive module can be further configured to receive a stiffness adjustment command indicative of a changed stiffness of the virtual object, and to send a drive command to the motor 1222 in response to the stiffness adjustment command. In some other embodiments, the motor drive module can be further configured to activate the motor 1222 to deliver a pull / release to the cables 1221 through the transmission system 1223 to adjust the stiffness to be perceived by the user's foot. In some embodiments, the change in the current stiffness of the virtual object can include being crushed or falling off the virtual object. The motor 1222 can include a drive shaft 1222a (as shown in FIG. 13(b)), and the transmission system 1223 can accordingly include a worm 1223a mounted and fixed on the drive shaft 1222a of the motor 1222 and rollers 1223b arranged corresponding to the rows (FIG. 13(b)). In addition, the rollers 1223b each have an axis perpendicular to the axis of the drive shaft 1222a and the worm 1223a, and are formed with threads to be screwed together with the worm 1223a, and each cable 1221 is wound around a corresponding roller 1223b, wherein the worm 1223a can rotate with the drive shaft 1222a and transmit the rotation to the rollers 1223b, and the rollers 1223b turn the cables 1221 to synchronously pull / release the free ends of the cables (1 input 5 output as shown in FIG. 13(c) and FIG. 13(d)).

[0082] Therefore, for the haptic stepping device 1200, a two-stage transmission system is designed, which consists of a multi-head worm transmission and a multi-knot cable drive transmission, wherein the former transmits the rotation from the motor to four rollers to simultaneously pull four independent cables, and the latter converts the pulling of each cable into the simultaneous folding of five pieces of curved paper-based metamaterials through five knots evenly located behind the five moving panels. In this way, the simultaneous control of the curved paper-based metamaterial tessellation with 20 components located in a 4x5 matrix can be achieved by only one motor, thereby forming an easy-to-handle and energy-saving actuation system similar to the actuation system of the haptic handheld device 700.

[0083] In some other embodiments, the microcontroller 1231 can be further configured to determine the amount of rotation of the motor 1222 according to the changed stiffness of the virtual object indicated in the stiffness adjustment command; and generate a drive command for the motor drive module to rotate the motor 1222 by the determined amount of rotation.

[0084] Benefiting from the scalability of origami structures, the curved origami based metamaterials are constructed in various sizes using different materials (e.g., plastic or steel) and then integrated into two types of haptic devices (i.e., a haptic handheld device for eliciting haptics and a haptic tread device (such as a tread pad) for generating full-body sensations) for experiencing (Fig. 1(a) and Fig. 1(b)). These two experiences produce more realistic sensory perceptions by successfully simulating the physiological and psychological responses of users, and they are expected to deliver highly immersive virtual experiences with wide application potentials in the fields of entertainment, teleoperation, medical treatment, and rehabilitation.

[0085] According to embodiments of the present disclosure, there is also provided an immersive VR / AR system for providing active mechanical haptics. As shown in Figure 14 The immersive VR / AR system 1400 can include the haptic handheld device 700 for providing active mechanical haptics according to any of the embodiments described above, alternatively or additionally, include the haptic tread device 1200 for providing active mechanical haptics according to any of the embodiments described above, as a haptic assembly.

[0086] The VR / AR engine 1430 can be configured to: simultaneously communicate with the VR / AR device 1440 and the haptic handheld device 700 and / or the haptic tread device 1200; and send stiffness adjustment commands indicative of a current stiffness of a virtual object in a VR / AR scene to the haptic assembly while tracking active grasping operations and / or active tread operations of the virtual object by a user. In some other embodiments, the VR / AR engine 1430 can also be configured to send a stream related to the VR / AR scene to the VR / AR device 1440.

[0087] In some embodiments, the VR / AR device 1440 can be configured to: communicate with the VR / AR engine 1430 to receive a stream related to a VR / AR scene and present the VR / AR scene to a user accordingly; and track active grasping and / or active tread operations of a virtual object in the VR / AR scene by the user.

[0088] For the immersive VR / AR system 1400, the control part of the haptic handheld device 700 can include a microcontroller, a sampling resistor module, and a wireless communication interface, wherein each panel is made of a substrate with a sensing layer (for sensing a loading strain) deposited thereon and changes its resistance when a loading strain is applied by a pressing / release operation on the top plate by a finger or a thumb or a foot of a user; the sampling resistor module is coupled to the sensing layer and converts the changed resistance thereof into a voltage change; and the microcontroller is coupled to the sampling resistor module and forwards the voltage change to the VR / AR engine via the wireless communication interface. The detailed implementation has been described in conjunction with the drawings related to the haptic handheld device 700, and thus is not repeated here.

[0089] The control unit of the haptic treading device 1200 can include a microcontroller, a distance sensing module configured to convert the sensed distance change caused by the active treading of the top plate by the user's foot into a voltage change, and a wireless communication interface; and the microcontroller is coupled to the distance sensing module and forwards the voltage change to the VR / AR engine via the wireless communication interface. The detailed implementation has been described in conjunction with the drawings related to the haptic treading device 1200, and therefore will not be repeated here.

[0090] The VR / AR engine 1430 can also be configured to convert the voltage change into the deformation of the virtual object and change the corresponding flow related to the VR / AR scene.

[0091] In the immersive VR / AR system 1400, the haptic perception generated by actively pressing the curved origami combined with the synchronous visual information from traditional VR devices can construct a highly immersive, touchable, closed-loop virtual world. At this time, with the curved origami as the key stiffness adjustment component, the user can actively and physically feel what she / he sees in VR through the touch or pressing action initiated by the user through the haptic device. The virtual scene (e.g., city landscape, ice surface, and grassland) serves as the input of the haptic device (e.g., mat and sphere). Based on the input, the folding angle is adjusted in Δβ by the integrated motor to simulate the expected stiffness response of the content seen by the user in the VR device. Therefore, the user can feel the mechanical stiffness of the object seen in the VR device in real time through active hand grasping or through body-centered stepping actions. On the other hand, the active interaction of the user with the curved origami (e.g., through pressing) is recorded as a change in resistance, which is achieved by depositing silver nanowires (AgNWs) as a sensing layer on the origami panel. Then, the changes are converted into voltage changes using an on-board microcontroller. The voltage changes on the haptic device are wirelessly communicated with the virtual environment engine (e.g., Unity) in the PC, and then wirelessly streamed into the VR device to present the necessary changes in real time (such as breaking the ice surface when the user triggers negative stiffness). Fig. 6(b) shows the relative resistance change (ΔR / R0) of the sensing layer when the top of the curved origami is cyclically actively pressed (for a height change, the nominal strain is 30%) at different folding angles (β = 120°, Δβ = 0°, 30°, 60°, and 90°). Here, two features are observed: first, the change in resistance has high repeatability during the cyclic pressing and releasing process; second, the folding angle Δβ shows negligible influence, which is important for changing the virtual environment using a general algorithm (i.e., Δβ-independent algorithm). Therefore, when a person actively interacts, the virtual environment is changed according to the deformation measured by the resistance change. Experimental results show that the device achieves very stable virtual-real synchronization via its wireless transmission system. It should be noted that the integrated motor drive cable is only activated when the folding angle of the curved origami needs to be changed according to the virtual scene. Then, it provides various stiffness perceptions to the user without the need for further complex control algorithms or additional actuation. Therefore, only about 150 mW of power dissipation is generated when adjusting the stiffness, thus realizing an energy-efficient system for active haptics triggered by humans.

[0092] According to embodiments of the present disclosure, a paper-folding based contact member for active mechanical haptics is also provided. The paper-folding based contact member can include a top plate, a bottom plate, and at least one sheet of curved paper-folding based metamaterial disposed between the top plate and the bottom plate, wherein the sheet of curved paper-folding based metamaterial can include panels, and a variable stiffness of the sheet of curved paper-folding based metamaterial is achieved by twisting the panels (similar to FIG. 2(b)) or by pulling / releasing the panels through connecting members (similar to FIG. 10(a)), wherein the variable stiffness encompasses a range from positive stiffness to negative stiffness.

[0093] The paper-folding based contact member that twists the panels and the paper-folding based contact member that pulls / releases the panels can be made of different materials in different proportions, but can employ the same working principle to adjust to have different stiffness responses.

[0094] The paper-folding based contact member, the haptic handheld device, or the haptic tread device according to the present disclosure employs a sophisticated curved paper-folding based metamaterial that allows users to actively generate and perceive mechanical haptics with controllable stiffness ranging from hard to soft and from positive stiffness to negative stiffness. And, an immersive VR / AR system that integrates the haptic handheld device and / or the haptic tread device can provide precise and stable virtual-to-real synchronization with active mechanical haptics, achieving a combination of visual, auditory, and active touch sensory perceptions in AR / VR haptic experiences, thereby providing many possibilities for potential applications including daily entertainment, industrial remote operation, psychological therapy, and physical rehabilitation.

[0095] The above description is intended to be illustrative and not restrictive. For example, the above-described examples (or one or more solutions thereof) can be used in combination with each other. For example, other embodiments can be used by one of ordinary skill in the art upon reading the above description. In addition, in the above specific embodiments, various features can be combined together to simplify the present disclosure. This should not be interpreted as an intent that features not required to be protected in the present disclosure are essential to any claim. On the contrary, the subject matter of the present disclosure can be less than the full range of features of a particular disclosed embodiment. Therefore, the following claims are incorporated herein as examples or embodiments in the specific embodiments, each claim alone as a separate embodiment, and it should be considered that these embodiments can be combined with each other in various combinations or arrangements. The scope of the present disclosure should be determined with reference to the full scope of the appended claims and the equivalents thereof.

[0096] The above-described embodiments are merely exemplary embodiments of the present disclosure and are not intended to limit the present disclosure. The scope of protection of the present application is defined by the claims. Those skilled in the art can make various modifications or equivalent replacements to the present application within the spirit and scope of the present disclosure, and such modifications or equivalent replacements should also be considered to fall within the scope of protection of the present application.

Claims

1. A paper-folding based contact member for active mechanical haptics, comprising: a top plate, a bottom plate, and at least one curved paper-folding based metamaterial disposed between the top plate and the bottom plate, a top end of the curved paper-folding based metamaterial being fixed on the top plate and a bottom end thereof being fixed on the bottom plate, the top plate being exposed to be contacted by a body part of a user; wherein the curved paper-folding based metamaterial comprises a panel having a single curved crease extending along a longitudinal direction thereof, the single curved crease dividing the panel into two faces on opposite sides thereof, the panel being configured to be folded along the single curved crease so as to form a folding angle between the two faces; the folding angle being configured to be adjusted by rotating the bottom plate so as to achieve a variable stiffness covering a positive stiffness to a negative stiffness when loaded along a vertical axis between the top plate and the bottom plate, the variable stiffness to be perceived by the body part of the user via contact with the top plate.

2. The origami-based contact member of claim 1, wherein, the paper-folding based contact member is formed as a button.

3. The origami-based contact member of claim 1, wherein, the at least one curved paper-folding based metamaterial comprises two curved paper-folding based metamaterials, one of which is axially symmetric to the other.

4. The origami-based contact member of claim 2, wherein, the bottom plate is circular and is provided with a shaft rotatable by an actuating mechanism.

5. The origami-based contact member of claim 4, wherein, the single curved crease is composed of two end extensions, a middle extension, and two circular-arc shaped cut slots, each of the circular-arc shaped cut slots connecting its adjacent end extension and the middle extension.

6. The origami-based contact member according to claim 4 or 5, characterized by the panel is made of a substrate having a sensing layer deposited thereon, the sensing layer being used to sense a strain loaded thereon and change its electrical property.

7. A haptic handheld device for providing active mechanical haptics, comprising: five paper-folding based contact members according to claim 6, the body part of the user being a finger or a thumb; an actuating mechanism and a control unit, wherein the control unit is configured to: communicate with a VR / AR engine so as to receive a stiffness adjustment command indicative of a current stiffness of a virtual object in a VR / AR scene when tracking an active grasping operation of the user on the virtual object; and control the actuating mechanism in response to the stiffness adjustment command so as to rotate the shaft of the bottom plate to adjust the stiffness to be perceived by the finger / thumb of the user; and a support shell for accommodating the five paper-folding based contact members, the actuating mechanism, and the control unit, the support shell being provided with five openings for exposing the top plates outside. the control unit comprises a microcontroller, a sampling resistor module, and a wireless communication interface, 8. The haptic hand-held device of claim 7, wherein, the sensing layer is configured to change its resistance when loaded with a strain by a pressing / releasing operation of the finger or thumb of the user on the top plate; the sampling resistor module is coupled to the sensing layer and converts the changed resistance thereof into a voltage change; ​ The microcontroller is coupled to the sampling resistor module and forwards the voltage change to the VR / AR engine via the wireless communication interface, so that the VR / AR engine subsequently converts the voltage change into a deformation of the virtual object and changes a corresponding VR / AR scene that the user will see via a VR / AR device.

9. The haptic hand-held device of claim 8, wherein, The control unit further comprises a motor driving module, and the actuating mechanism comprises a motor and a transmission system, The microcontroller is further configured to, if the deformation of the virtual object causes a change in its current stiffness, receive a stiffness adjustment command from the VR / AR engine indicating the changed stiffness of the virtual object, and send a driving command to the motor driving module in response to the stiffness adjustment command; The motor driving module is further configured to start the motor to transmit rotation to the shaft of the bottom plate via the transmission system, so as to adjust the stiffness to be perceived by the user's fingers / thumb.

10. The haptic hand-held device of claim 9, wherein, The change in the current stiffness of the virtual object includes being crushed or falling off the virtual object.

11. The haptic hand-held device of claim 9, wherein, The motor comprises a drive shaft, and the transmission system comprises a worm installed and fixed to the drive shaft of the motor, a spool threadedly connected with the worm, at least four rollers, five universal joints, and a cable; The at least four rollers each have an axis parallel to the axis of the spool and perpendicular to the axes of the drive shaft and the worm, and are connected with the bottom plate of the five paper-based contact members via the at least four universal joints; the cable is wound around the spool and the at least four rollers in sequence, so that the worm rotates and transmits rotation to the spool as the drive shaft rotates, the spool rotates the cable to rotate the at least four rollers, thereby synchronously transmitting rotation to the bottom plate of the five paper-based contact members.

12. The haptic hand-held device of claim 9, wherein, The microcontroller is further configured to determine the amount of rotation of the motor according to the changed stiffness of the virtual object indicated in the stiffness adjustment command, and generate a driving command for the motor driving module to make the motor rotate by the determined amount of rotation.

13. The haptic hand-held device of claim 7, wherein, The support shell is spherical in shape and has five slots for respectively accommodating the five paper-based contact members, each of the slots is provided with a sliding guide for limiting the compression range of the corresponding paper-based contact member.

14. The haptic hand-held device of claim 13, wherein, The five paper-based contact members are installed in the support shell according to a common human gripping posture, and the paper-based contact member for the thumb is located on the side of the support shell opposite to the side of the other four fingers.

15. The haptic hand-held device of claim 11, wherein, The transmission system comprises four rollers, and the paper-based contact members for the thumb and the middle finger are connected with the same roller.

16. The haptic hand-held device of claim 11, wherein, The transmission system further comprises a tensioning roller, and the portion of the cable between the spool and the four rollers is tensioned by the tensioning roller.

17. A paper-based contact member for active mechanical haptics, comprising: a top plate exposed to the outside to be contacted by a body part of a user; a bottom plate; a plurality of curved paper-based metamaterials disposed between the top plate and the bottom plate and arranged into a plurality of rows; and a plurality of cables corresponding to the plurality of rows, such that each row has an independent cable; each of the curved paper-based metamaterials has a top end and a bottom end, the top end is fixed on the top plate, and the bottom end is fixed on the bottom plate; each of the curved paper-based metamaterials includes a panel having a single curved crease extending along a longitudinal direction thereof, the single curved crease divides the panel into two faces on opposite sides thereof, the panel is configured to be folded along the single curved crease to form a folding angle between the two faces; a first hole is formed on one of the two faces, and a second hole is formed on the other of the two faces; for each row of curved paper-based metamaterials, the corresponding independent cable sequentially passes through the two holes cut on the panel, and is knotted at a side behind each panel, so as to be synchronously pulled / released to adjust the folding angle of the panel, so as to achieve a variable stiffness covering positive stiffness to negative stiffness which will be perceived by a body part of the user via contact with the top plate when loaded along a vertical axis between the top plate and the bottom plate.

18. The paper-based contact member according to claim 17, wherein the paper-based contact member is formed as a stepping member, and the body part is a foot.

19. The origami-based contact member of claim 17, wherein, the single curved crease is composed of two end extensions, a middle extension, and two circular-arc-shaped cut grooves, each of the cut grooves connecting its adjacent end extension and the middle extension.

20. The origami-based contact member of claim 18 or 19, wherein, a distance sensor is further included, which is arranged between the top plate and the bottom plate to detect displacement of the top plate in a vertical direction.

21. The origami-based contact member of claim 17, wherein, a plurality of pairs of collars and posts are further included, the posts being fixed on a periphery of the plurality of curved paper-based metamaterials and distributed on the bottom plate, and the collars being fixed on a bottom side of the top plate corresponding to the posts, such that each collar is slidably sleeved on a corresponding post.

22. The origami-based contact member of claim 21, wherein, a sliding range between the collars and the posts is preset to limit a depression range of the paper-based contact member.

23. The origami-based contact member of any one of claims 17-19, wherein, each cable is independent of each other and has a free end extending out of a proximal panel so as to be independently pulled / released.

24. A haptic stepping device for providing active mechanical haptics, comprising: the paper-based contact member according to claim 23, the body part of the user being a foot; and an actuating mechanism including the cables and a control portion, wherein the control portion is configured to communicate with a VR / AR engine to receive a stiffness adjustment command indicating a current stiffness of a virtual object in a VR / AR scene when tracking active stepping operations of the user on the virtual object; the actuating mechanism is controlled in response to the stiffness adjustment command to synchronously pull / release the cables to adjust the stiffness to be perceived by the foot of the user.

25. The haptic treadle device of claim 24, wherein, The control part comprises a microcontroller, a distance sensing module, and a wireless communication interface; The distance sensing module is configured to convert the sensed distance change caused by the active treading of the user's foot on the top plate into a voltage change; The microcontroller is coupled to the distance sensing module and forwards the voltage change to the VR / AR engine via the wireless communication interface, so that the VR / AR engine subsequently converts the voltage change into the deformation of the virtual object and changes the corresponding VR / AR scene that the user will see via the VR / AR device.

26. The haptic treadle device of claim 25, wherein, The control part further comprises a motor driving module, the actuating mechanism comprises a motor and a transmission system, and the transmission system comprises the cable; The microcontroller is further configured to, if the deformation of the virtual object causes a change in its current stiffness, receive a stiffness adjustment command from the VR / AR engine indicating the changed stiffness of the virtual object, and send a driving command to the motor driving module in response to the stiffness adjustment command; The motor driving module is further configured to start the motor to transmit the pulling / release to the cable through the transmission system, so as to adjust the stiffness to be perceived by the user's foot.

27. The haptic treadle device of claim 26, wherein, The change in the current stiffness of the virtual object comprises being crushed or falling off the virtual object.

28. The haptic treadle device of claim 26, wherein, The motor comprises a driving shaft, and the transmission system further comprises a worm screw mounted and fixed to the driving shaft of the motor and a plurality of rollers arranged corresponding to the plurality of rows; The rollers each have an axis perpendicular to the axis of the driving shaft and the worm screw and are formed with threads to be threadedly connected with the worm screw; Each cable is wound around a corresponding roller; The worm screw rotates with the driving shaft and transmits the rotation to the rollers, and the rollers rotate the cables to synchronously pull / release the free ends of the cables.

29. The haptic treadle device of claim 26, wherein, The microcontroller is further configured to determine the rotation amount of the motor according to the changed stiffness of the virtual object indicated in the stiffness adjustment command, and generate a driving command for the motor driving module to make the motor rotate by the determined rotation amount.

30. An immersive VR / AR system for providing active mechanical haptics, comprising: a haptic handheld device for providing active mechanical haptics according to any one of claims 7 to 16 and / or a haptic treading device for providing active mechanical haptics according to any one of claims 24 to 29 as a haptic assembly; a VR / AR engine configured to: communicate with both the VR / AR device and the haptic assembly; send a stiffness adjustment command indicating the current stiffness of a virtual object in a VR / AR scene to the haptic assembly while tracking the active grasping and / or active treading operation of the user on the virtual object in the VR / AR scene; and send a stream related to the VR / AR scene to the VR / AR device; and a VR / AR device configured to: communicate with the VR / AR engine to receive the stream related to the VR / AR scene and present the VR / AR scene to the user accordingly; and tracking active grasping and / or active treading operations of the user on the virtual object in the VR / AR scene. 31.The immersive VR / AR system of claim 30, wherein, the control part of the haptic handheld device comprises a microcontroller, a sampling resistor module, and a wireless communication interface, wherein each panel is made of a substrate with a sensing layer deposited thereon for sensing loading strain and changing its resistance when loaded by the pressing / release operation of the user’s finger or thumb or foot; the sampling resistor module is coupled to the sensing layer and converts its changed resistance into a voltage change; and the microcontroller is coupled to the sampling resistor module and forwards the voltage change to the VR / AR engine via the wireless communication interface; the control part of the haptic treading device comprises a microcontroller, a distance sensing module, and a wireless communication interface, wherein the distance sensing module is configured to convert the sensed distance change caused by the active treading of the user’s foot on the top plate into a voltage change; the microcontroller is coupled to the distance sensing module and forwards the voltage change to the VR / AR engine via the wireless communication interface; and the VR / AR engine is further configured to convert the voltage change into the deformation of the virtual object and modify the corresponding stream associated with the VR / AR scene. 32.A foldable contact member for active mechanical haptics, comprising: a top plate; a bottom plate; and at least one curved foldable metamaterial placed between the top plate and the bottom plate, wherein the curved foldable metamaterial comprises a panel having a single curved fold line extending along its longitudinal direction, the single curved fold line dividing the panel into two faces at its opposite sides, the panel being configured to be folded along the single curved fold line so as to form a folding angle between the two faces; wherein the variable stiffness of the curved foldable metamaterial is achieved by twisting the panel or by pulling / release the panel through a connecting member passing through the panel to adjust the folding angle; and wherein the variable stiffness covers positive stiffness to negative stiffness.

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