CN108608419B

CN108608419B - Closed cavity, soft muscle, soft robot driving system and robot system

Info

Publication number: CN108608419B
Application number: CN201611128443.4A
Authority: CN
Inventors: 王峥; 易娟; 陈志强
Original assignee: Shenzhen Institute of Research and Innovation HKU
Current assignee: Shenzhen Institute of Research and Innovation HKU
Priority date: 2016-12-09
Filing date: 2016-12-09
Publication date: 2024-06-18
Anticipated expiration: 2036-12-09
Also published as: CN108608419A

Abstract

The present invention relates to a closed cavity, a soft muscle, a soft robot drive system and a robot system, wherein the closed cavity has a paper folding structure and defines an inner cavity, wherein the paper folding structure comprises: a body having two axial ends and a plurality of first axial folded ridges converging to an axial extremity, at least one of the two axial ends having a fold angle tapering toward the axial extremity; at least one pair of end folding ridges integrally formed on the body, wherein each end folding ridge tapers toward an axial end; and a middle folded ridge integrally formed on the body and connected between the at least one pair of end folded ridges; wherein the closed cavity is configured to be transitionable from a collapsed state to a radially expanded and axially contracted expanded state by inflating the inner cavity. The present invention improves the closed cavity to construct a soft muscle with a higher force to weight ratio and lower driving pressure.

Description

Closed cavity, soft muscle, soft robot driving system and robot system

Technical Field

The invention relates to the technical field of soft robots, in particular to a closed cavity, soft muscles, a soft robot driving system and a robot system.

Background

In recent years, soft actuators have attracted increasing attention from researchers due to their better compliance, higher safety and stronger power, which has prompted their development in daily and industrial use. For example, the soft muscle has unique passive flexibility and adaptability, so that the soft muscle is not absolute rigid at any working point, and can deform within a certain range under the action of external force, so that the soft muscle has adaptability and safety incomparable with those of a traditional robot actuator under the unexpected conditions of collision, impact and the like. The soft muscle is particularly suitable for application occasions such as wearable robot equipment or service robots working in a general environment.

US7779747B2 discloses such a soft muscle comprising an actuator having a first end, a second end and a radially expandable bladder assembly extending between the ends, the actuator being externally connected to a source of pressurized fluid. The bladder assembly also includes an inner lumen. In addition, a substantially fixed volume container is disposed within the interior cavity. Wherein the bladder assembly is configured to radially expand and axially contract when a volume of fluid is introduced from the container into the interior cavity. However, such soft muscles still need further improvement due to the lower contraction and higher driving pressure required to generate the same force.

Disclosure of Invention

The present invention aims to provide an improved closed cavity suitable for application to soft muscles.

The present invention also aims to provide a soft muscle using the improved closed cavity described above, which is capable of producing a higher contraction ratio at lower driving pressures.

The present invention is also directed to a soft robotic drive system employing the improved soft muscles described above.

The present invention is also directed to a robotic system employing the improved soft robotic drive system described above.

According to one aspect of the present invention, there is provided a closed cavity having a paper folding structure and defining an inner cavity, wherein the paper folding structure comprises: a body having two axial ends and a plurality of first axial folded ridges converging to an axial extremity, at least one of the two axial ends having a fold angle tapering toward the axial extremity; at least one pair of end folding ridges integrally formed on the body, wherein each end folding ridge tapers toward an axial end; and a middle folded ridge integrally formed on the body and connected between the at least one pair of end folded ridges; wherein the closed cavity is configured to be transitionable from a collapsed state to a radially expanded and axially contracted expanded state by inflating the inner cavity.

When the inflatable inner cavity is filled with a pressure fluid, the closed cavity is radially inflated or expanded by expanding the axially folded ridges, the end folded ridges and the middle folded ridge, which inflation or expansion can be achieved with a small driving pressure. Meanwhile, the closed cavity can realize the integral shrinkage in the axial direction by means of the angle change of the folding angle, and the maximum acting force which can be generated is prevented from being reduced due to the fact that part of axial shrinkage force is counteracted by end face expansion. The closed cavity has simple structure, easy operation and high safety.

Preferably, the central folding ridge comprises a plurality of spaced apart second axial folding ridges. In this way, a middle folded ridge of simple construction is provided.

Preferably, the central folding ridge comprises a plurality of corrugated folding ridges. In this way, another structurally simple central folded ridge is provided.

Preferably, the paper folding structure is made of a flexible, non-stretchable film material. Thus, the counteracting of the tension characteristic of the material to the acting force generated by the pressure fluid is avoided, and the force-weight ratio of soft muscles is reduced.

According to another aspect of the present invention, there is provided a soft muscle, comprising: the closed cavity; a constraining mechanism deformably surrounding the closed cavity to convert radial expansion into axial contraction; an end connector connected to the limiting mechanism; and a conduit passing through the end connector and communicating with the interior cavity of the closed cavity.

When the closed cavity is pressurized to radially expand, the limiting mechanism surrounding the closed cavity is deformed, so that axial contraction and radial expansion are generated, and the radial expansion of the closed cavity is converted into axial contraction. At the same time, the limiting mechanism can effectively limit the closed cavity, prevent the closed cavity from being excessively expanded in the radial direction, improve the maximum internal pressure which can be born by the closed cavity, and improve the maximum contraction stroke and the maximum contraction force which can be generated. Because the closed cavity in the inner part can be passively deformed under the action of external force, the soft muscle has a certain degree of passive flexibility and adaptability under any working state, namely the length of the soft muscle can be passively changed within a certain range under the action of external force. Therefore, the soft muscle has passive flexibility along the radial direction no matter driven or not, and can be bent radially at will without obstructing the movement along the axial direction and generating pulling force.

Preferably, the restraining mechanism comprises a mesh woven structure. The geometric characteristics of the mesh braid help to convert radial expansion of the closed cavity into axial contraction.

Preferably, the end connector comprises: a collar having a flange and an axial through hole adapted to pass the pipe; a locking ring sleeved on the ring for locking the end of the limiting mechanism; and a retaining cap connected to the collar and retaining the locking ring on the flange. In this way, a simple and easy to implement end connection is provided.

Preferably, the locking ring comprises an inner ring and an outer ring, wherein staggered male and female locking formations are provided between the inner ring and the outer ring, and the ends of the restraining means are locked between the male and female locking formations.

Preferably, the end connector is made of a plastic material suitable for 3D printing.

According to still another aspect of the present invention, there is provided a soft robot driving system, including: a pneumatic source; the foregoing soft muscle wherein the lumen is adapted to be inflated with a gas; and a control valve for controlling the flow direction and the flow rate of the gas.

According to still another aspect of the present invention, there is provided a soft robot driving system, including: a hydraulic source; the foregoing soft muscle wherein the lumen is adapted to be inflated with a liquid; and a control valve for controlling the flow direction and the flow rate of the liquid.

According to yet another aspect of the present invention, a robotic system is provided, wherein the robotic system comprises a plurality of the aforementioned soft robotic drive systems comprising a pneumatic source or a plurality of the aforementioned soft robotic drive systems comprising a hydraulic source, wherein at least a portion of the soft robotic drive systems are controlled by a common control valve. Thus, the soft robotic drive system sharing the control valve will simultaneously produce motion.

According to yet another aspect of the present invention, there is provided a robotic system comprising a plurality of the aforementioned soft robotic drive systems comprising a pneumatic source or a plurality of the aforementioned soft robotic drive systems comprising a hydraulic source, wherein each soft robotic drive system is controlled by an independent control valve.

Additional features and advantages of the application will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following, or may be learned from the practice of the application. Thus, the soft robotic drive systems controlled by the independent control valves will generate motion independent of each other.

Drawings

Embodiments of the present invention are described in detail below with reference to the attached drawing figures, wherein:

FIG. 1 is a schematic view of a closed cavity according to an embodiment of the invention;

FIG. 2 is a partial schematic view of a body of a closed cavity according to an embodiment of the invention;

FIG. 3 is a partial schematic view of an end folded ridge of a closed cavity according to an embodiment of the invention;

FIG. 4 is a partial schematic view of a central folded ridge of a closed cavity according to an embodiment of the invention;

FIG. 5 is a schematic view of a closed cavity in a folded condition, wherein three first axially folded ridges are provided, according to an embodiment of the invention;

FIG. 6 is a schematic view of the closed cavity according to FIG. 5 in an expanded state;

FIG. 7 is a schematic view of a closed cavity in a folded condition with four first axially folded ridges provided in accordance with an embodiment of the present invention;

FIG. 8 is a schematic view of the closed cavity according to FIG. 7 in an expanded state;

FIG. 9 is a schematic view of a closed cavity in a folded condition, wherein five first axially folded ridges are provided, according to an embodiment of the invention;

FIG. 10 is a schematic view of the closed cavity according to FIG. 9 in an expanded state;

FIG. 11 is a schematic view of a soft muscle according to an embodiment of the present invention with the closed cavity in an expanded state;

FIG. 12 is a schematic view of the soft muscle according to FIG. 11, wherein the closed configuration is in a folded state;

FIG. 13 is a schematic illustration of an end connector mated with a mesh fabric in accordance with an embodiment of the invention;

FIG. 14 is a partial cross-sectional view according to FIG. 13;

Fig. 15 and 16 are descriptions of experimental and theoretical results.

In the present invention, the same or similar reference numerals denote the same or similar features.

Reference numerals illustrate:

1. soft muscle; 10. a closed cavity structure; 100. a body; 101. an axial end; 102. an axial end; 103. a first axially folded ridge; 105. folding angles; 200. an end folded ridge; 300. a middle folding ridge; 301. a second axial folded ridge; 303. corrugated folding ridges; 400. an inner cavity; 500. a restriction mechanism; 600. an end connector; 601. a loop; 602. a flange; 603. an axial through hole; 604. a locking ring; 605. a holding cover; 606. an inner ring; 607. an outer ring; 700. and (5) a pipeline.

Detailed Description

Referring now to the drawings, illustrative aspects of the disclosed robotic system are described in detail. Although the drawings are provided to present some embodiments of the invention, the drawings are not necessarily to scale and certain features may be exaggerated, removed, or partially sectioned to better illustrate and explain the present disclosure. The position of part of components in the drawings can be adjusted according to actual requirements on the premise of not affecting the technical effect. The appearances of the phrase "in the drawings" or similar language in the specification do not necessarily refer to all figures or examples.

Certain directional terms used hereinafter to describe the drawings, such as "inner", "outer", "above", "below" and other directional terms, will be understood to have their normal meaning and refer to those directions as they would be when viewing the drawings. Unless otherwise indicated, directional terms described herein are generally in accordance with conventional directions as understood by those skilled in the art.

The terms "first," "second," and the like, as used herein, do not denote any order, quantity, or importance, but rather are used to distinguish one element from another.

Referring to fig. 1-4, there is shown in particular a schematic view of a closed cavity 10 according to an embodiment of the present invention, including a folded paper structure and an inflatable interior cavity 400 defined by the folded paper structure (see fig. 11 and 12). As shown, the paper folding structure includes an elongated body 100 (waterbomb pattern), end folding ridges (TREE LEAVES PATTERN) 200 and middle folding ridges (miura-ori pattern) 300 integrally formed on the body 100. The inner cavity 400 is adapted to be filled with a pressurized fluid, such as a liquid or a gas. The body 100 has two opposite axial ends 101 and 102 along its axial direction, each of which is provided with four first axially folded ridges 103 converging towards the axial extremity, dividing the end faces in four and constructing a fold angle 105 tapering towards the axial extremity. During filling/discharging of the pressurized fluid into the inner cavity 400, the angle of the fold 105 may change as the closed cavity 10 radially expands or contracts, thereby causing the closed cavity 10 to contract or expand in an axial direction. In a not shown embodiment, one of the two axial ends 101 and 102 is formed with a bevel 105, which also enables axial contraction upon radial expansion of the closed cavity 10.

The end folding ridge 200 and the middle folding ridge 300 are integrally formed on the body 100, respectively. Fig. 1 illustrates an end fold ridge 200 of one embodiment. As shown, a pair of slightly smaller end folding ridges 200 are oppositely disposed at both ends of the body 100, and another pair of slightly larger end folding ridges 200 are disposed at the outer sides thereof. Wherein each end fold ridge 200 tapers toward an axial end. Figure 3 shows further end fold ridges 200 which are nested on the body 100. The middle folding ridge 300 is formed between the end folding ridges 200. In the embodiment shown in fig. 1, the central folding ridge 300 is formed by a plurality of second axial folding ridges 301 that are parallel to each other and spaced apart. In the embodiment shown in fig. 4, the middle folding ridge 300 comprises a plurality of zigzag corrugated folding ridges 303.

The inner cavity 400 of the closed cavity 10 is communicated with the outside through a pipeline. When the internal pressure of the inner cavity 400 is made higher than the external pressure by filling with a pressurized gas/liquid, for example, the closed cavity 10 expands/expands in the radial direction while contracting in the axial direction due to the presence of the plurality of folded ridges 103, 200, 300 and the folded corners 105. Thus, the closed cavity 10 transitions from an original folded state to an expanded state that expands radially and contracts axially as the internal pressure is increased to within the maximum extent allowed by the material (e.g., film material) from which the closed cavity 10 is made. The ratio of axial contraction to radial expansion of the closed cavity 10 can be controlled by varying the design of the folded ridges. Also with the same original length and diameter and the same thickness of material from which the closed cavity 10 is made, the greater the number of first axially folded ridges 103, the greater the proportion of radial expansion. Typically, the first axially folded ridge 103 is 3-8, i.e. each end face is equally divided by 3-8 identical structures.

Fig. 5 to 10 show schematic views of several closed cavities 10 seen from the end, wherein fig. 5, 7 and 9 are schematic views of three closed cavities 10 in a folded state, respectively, and fig. 6, 8 and 10 are schematic views of three closed cavities 10 in an unfolded state, respectively, wherein in these figures, solid lines represent top folding lines of the folded ridge in a natural state and broken lines represent bottom folding lines of the folded ridge in a natural state. Referring to fig. 5 and 6, the closed cavity 10 is formed with three first axially folded ridges 103 (i.e., n=3) at the end that trisect the end surface. The closed cavity 10 of fig. 5 is unfolded to form a shape similar to a truncated equilateral triangle as shown in fig. 6. Referring to fig. 7 and 8, the closed cavity 10 is formed with four first axially folded ridges 103 (i.e., n=4) at the end portions that quarters the end faces. The closed cavity 10 of fig. 7, when expanded, forms a truncated square-like shape as shown in fig. 8. Referring to fig. 9 and 10, the closed cavity 10 is formed with five first axially folded ridges 103 (i.e., n=5) at the ends that bisect the end face five. The closed cavity 10 of fig. 9 is unfolded to form a shape similar to a truncated regular pentagon as shown in fig. 10.

Preferably, the closed cavity 10 is made of a flexible, non-stretchable film material, so as to avoid a reduction in the shrinkage ratio caused by the forces exerted by the counteracting pressure fluid due to the stretching of the material itself. "Flexible non-stretchable materials" are those materials known to those skilled in the art, and the present application is not directed to improvements in materials. To facilitate filling with pressurized fluid, the closed cavity 10 may be closed at one end and open at the other end to facilitate plugging of the tubing.

Preferably, the closed cavity 10 can be completed by means of 3D printing, so that it has a good reproducibility and a high precision.

The closed cavity 10 described above can greatly improve the performance of soft muscles when applied thereto, as it can effectively reduce the energy loss during inflation. The paper folding structure in the closed cavity 10 creates movement by rearranging and bending the edges, avoiding stretching of the inner material when the cavity made of elastic material expands. Furthermore, the paper folding structure also makes the maximum working pressure independent of the cavity wall thickness.

The following will describe in detail a soft muscle (or Fiber-reinforced paper folding robot actuator, fiber-reinforced Origamic Robotic Actuator, abbreviated as FORA) applied to the above-described closed cavity 10.

Referring to fig. 11 and 12, fig. 11 shows a schematic view of a soft muscle 1 according to an embodiment of the present invention in an unfolded state (or active state), and fig. 12 shows a schematic view of the soft muscle in a folded state (or natural state). As shown, the soft muscle 1 includes a closed cavity 10, a restriction mechanism 500 surrounding the closed cavity 10 for restricting and guiding movement, and end connectors 600 mounted to both ends of the restriction mechanism 500. Wherein the closed cavity 10 may be any of the previously described closed cavities capable of axial contraction and radial expansion upon being filled with a pressurized fluid. In the illustrated embodiment, a closed cavity 10 as shown in fig. 1 is employed.

The restriction mechanism 500 is disposed outside the closed cavity 10. In a natural state, the axial length of the limiting mechanism 500 is greater than the axial length of the closed cavity 10, and the end connector 600 is connected only with the limiting mechanism 500 and is not in contact with the closed cavity 10. When the closure cavity 10 is pressurized to radially expand to an activated state, the restraining mechanism 500 is deformed therewith, converting the radial expansion of the closure cavity 10 to an axial contraction. Meanwhile, the restriction mechanism 500 acts as an external restriction mechanism to effectively prevent the closing chamber 10 from being excessively expanded in the radial direction, thereby increasing the maximum internal pressure that the closing chamber 10 can withstand, and thus increasing the maximum contraction stroke and the maximum contraction force that can be generated.

Referring to fig. 11 and 12, the restraining mechanism 500 is preferably a mesh braid structure constructed by two helically extending fiber ribbons intersecting each other. A strip extending from any node may oscillate about that node. Fig. 11 shows a schematic view of the soft muscle 1 with the closed cavity 10 in the deployed state. With radial expansion of the closed cavity 10, the restriction mechanism 500 as a whole is contracted in the axial direction and expanded in the radial direction. Referring next to fig. 12, a schematic view of the soft muscle 1 is shown with the closed cavity 10 in a folded state. As the pressurized fluid within the interior chamber 400 is expelled, the restriction mechanism 500 also contracts radially and expands axially. The pressurized radial expansion of the closed cells 10 is effectively translated into a reduction in axial length by the geometric characteristics of the reticulated woven fibrous structure.

The end connector 600 may be made of a rigid material such as metal or plastic, preferably a material suitable for 3D printing. "materials suitable for 3D printing" herein refers to those materials known to those skilled in the art and does not involve modifications to the materials. End connector 600 is applied to restraining mechanism 500 from both ends to effectively secure restraining mechanism 500 and provide a mounting base for further connection to an external other system. Referring to fig. 13 and 14, there is shown in particular an end connector 600 according to one embodiment of the invention comprising a collar 601 having a flange 602 and an axial through hole 603, a locking ring 604 that fits over the collar 601, and a retaining cap 605 that fits over the collar 601 and compresses the locking ring 604 against the flange 602. The axial through hole 603 of the collar 601 is adapted to pass through the conduit 700 supplying the closed cavity 10 with a pressurized fluid. A retaining cap 605, for example, is threadably engaged on collar 601, and may be used to further connect to an external other system. The netting of the restraint mechanism 500 is locked by the locking ring 604.

Locking ring 604 includes a detachable inner ring 606 and an outer ring 607. As shown, the inner ring 606 fits over the collar 601 and the outer ring 607 is, for example, threadably engaged to the inner ring 606.

An alternating male and female locking arrangement is preferably formed between the inner ring 606 and the outer ring 607 to prevent the end of the restraining mechanism 500 from backing out. In the embodiment shown in fig. 14, the inner ring 606 and the outer ring 607 are each formed with adjoining concave and convex portions in the axial direction. In the engaged state, the convex portion of the inner ring 606 is inserted into the concave portion of the outer ring 607, and the convex portion of the outer ring 607 at the end is inserted into the gap between the inner ring 606 and the collar 601. Thus, the plurality of protrusions and recesses between the inner ring 606 and the outer ring 607 form an axially staggered male-female locking arrangement. The end fibers of the mesh-like woven structure are locked in the concave-convex locking structure to be difficult to separate, so that the mesh-like woven structure is effectively fixed. The male and female locking structure increases the maximum force by enlarging the contact area, increasing the maximum load of the end connector 600. Although fig. 14 specifically illustrates the male and female locking structures by way of example, it will be appreciated by those skilled in the art that the specific form of the male and female locking structures is not limited thereto, and that the specific number and shape of the protrusions and recesses may be set as desired, provided that the protrusions are axially offset from each other and protrude into the corresponding recesses after engagement, to some extent, to function as end fibers of the locking limiting mechanism 500.

The soft muscles are driven by a pressurized fluid, such as air or hydraulic pressure. Axially shortens when driven and may create an axial pulling force. Meanwhile, the internal closed cavity 10 can be passively deformed under the action of external force, so that the soft muscle has a certain degree of passive flexibility and adaptability under any working state, namely the length of the soft muscle can be passively changed within a certain range under the action of external force. In the illustrated embodiment of the invention, the maximum contraction stroke of the soft muscle may be up to 50%. Whether driven or not, the soft muscle has passive flexibility along the radial direction all the time, and can be bent radially at will without obstructing the movement in the axial direction and generating tension.

The soft muscle of the present invention has a very high tensile weight ratio and can be driven by very low pressure. Experiments have shown that under a driving pressure of 1 standard atmospheric pressure (1 Bar), a passive diameter of 30 mm of such a muscle with a dead weight of 20 g can produce an axial tension of up to 280 newtons, with a weight ratio of the tension reaching a surprising 1440. At the same time, the muscle can achieve a large stroke, and with sufficient drive, a contraction ratio approaching 0.5 can be achieved. Compared with the maximum stroke of the existing pneumatic soft muscle which is less than 0.3, the pneumatic soft muscle is improved by more than 60 percent. In terms of driving and stress, the soft muscle of the invention has lower driving pressure and higher generated pulling force under the same materials, sizes and weights, and the performance is obviously improved.

Fig. 15 and 16 describe experimental and theoretical results. In which fig. 15 shows a free space (FREE SPACE) test, experimental results of a FORA (denoted as I in the figure), PAMs purchased from Shadow Robot company (hereinafter referred to as Shadow, denoted as II in the figure), and a pneumatic actuator (Pneumatic Actuator) (hereinafter referred to as fest, denoted as III in the figure) from fest company according to the present application are compared. In addition, FIG. 15 also shows the simulation results of FORA (modeled results). As is clear from fig. 15, there is a threshold pressure for Shadow and fest. Due to the non-linear elasticity of the lumen, shadow and Festo do not produce stroke displacements when the pressure is below 50kPa and 100kPa, respectively. While the FORA has no threshold pressure and its shrinkage increases rapidly. Specifically, the above experiments showed a maximum shrinkage ratio of 45% at a drive pressure of 100kPa (14.4 psi). This result was also demonstrated by static simulation. The stroke of the FORA has been improved by nearly 50% compared to conventional PAMs.

FIG. 16 shows an isotonic test (Isotonic test) showing experimental results of FORA (labeled I in the figure) and Shadow (labeled II in the figure), and simulated results of FORA. As shown, the pulling force decreases with increasing contraction until maximum contraction is reached. When a pressure of 100kPa is applied, the FORA shows a higher pull force than Shadow at the same shrinkage than Shadow.

The soft muscle is particularly suitable for application in a soft robotic drive system.

According to one embodiment, the soft robotic drive system charges the inflatable interior cavity 400 of the closed cavity 10 with a liquid via a hydraulic source. The flow rate and direction of the liquid can be controlled by means of a control valve, such as a solenoid valve.

According to another embodiment, the soft robotic drive system charges the inflatable interior cavity 400 of the closed cavity 10 with gas via a gas pressure source. The flow and direction of the gas can be controlled by means of a control valve, such as a solenoid valve.

This means that the soft robotic drive system of the present invention is not strictly limited to the form of the fluid pressure source, and can be filled with liquid or gas as needed without concern for sealing due to the presence of the closed cavity 10. This is different from those existing systems that use only a single fluid-like pressure source due to sealing conditions.

A combination of a plurality, e.g. 20, of the above described soft robotic drive systems may be used to construct the robotic system. Or the combination of less than 20 soft robot driving systems is also possible, and the specific number is determined according to the actual situation. The soft robot driving systems may be all systems using hydraulic sources, all systems using pneumatic sources, or some systems using pneumatic sources and some systems using hydraulic sources.

The soft robot drive systems may all be controlled by a common control valve so that all the soft robot drive systems will act simultaneously. Or one part of the software robot driving systems can be controlled by a shared control valve, and the other part of the software robot driving systems are respectively provided with independent control valves, so that the software robot driving systems sharing the control valves can act simultaneously, and the software robot driving systems with the independent control valves can act independently. Of course, all the soft robot driving systems may have independent control valves, so that all the soft robot driving systems will generate actions independently of each other.

It should be understood that although the present disclosure has been described in terms of various embodiments, not every embodiment is provided with a separate technical solution, and this description is for clarity only, and those skilled in the art should consider the disclosure as a whole, and the technical solutions in the various embodiments may be combined appropriately to form other embodiments that will be understood by those skilled in the art.

The foregoing is illustrative of the present invention and is not to be construed as limiting the scope of the invention. Any equivalent alterations, modifications and combinations thereof will be effected by those skilled in the art without departing from the spirit and principles of this invention, and it is intended to be within the scope of the invention.

Claims

1. A closed cavity (10) having a paper folding structure and defining an interior cavity (400), wherein the paper folding structure comprises:

a body (100) having two axial ends (101, 102) and a plurality of first axial folded ridges (103) converging to an axial extremity, at least one of the two axial ends (101, 102) having a fold angle (105) tapering towards the axial extremity;

At least one pair of end folding ridges (200) integrally formed on the body (100), wherein each end folding ridge (200) tapers toward an axial end; and

A middle folding ridge (300) integrally formed on the body (100) and connected between the at least one pair of end folding ridges (200);

wherein the closed cavity (10) is configured to be transitionable from a collapsed state to a radially expanded and axially contracted expanded state by inflating the inner lumen (400).

2. The closed cavity (10) according to claim 1, wherein the central folded ridge (300) comprises a plurality of spaced apart second axial folded ridges (301).

3. The closed cavity (10) according to claim 1, wherein the mid-fold ridge (300) comprises a plurality of corrugated fold ridges (303).

4. A closed cavity (10) according to any of claims 1 to 3, wherein the folded paper structure is made of a flexible, non-stretchable film material.

5. A soft muscle (1), comprising:

The closed cavity (10) of any of claims 1 to 4;

a restraining mechanism (500) deformably surrounding the closed cavity (10) to convert radial expansion into axial contraction;

An end connector (600) connected to the limiting mechanism (500); and

A conduit (700) passing through the end connector (600) and communicating with the interior cavity (400) of the closed cavity (10).

6. The soft muscle (1) of claim 5, wherein the restraining mechanism (500) comprises a mesh-like woven structure.

7. The soft muscle (1) of claim 5, wherein the end connector (600) comprises:

-a collar (601) having a flange (602) and an axial through hole (603) adapted to the passage of said pipe (700);

a locking ring (604) which is sleeved on the ring (601) and is used for locking the end part of the limiting mechanism (500); and

A retaining cap (605) connected to the collar (601) and retaining the locking ring (604) on the flange (602).

8. The soft body muscle (1) of claim 7, wherein the locking ring (604) comprises an inner ring (606) and an outer ring (607), wherein an alternating male and female locking structure is provided between the inner ring (606) and the outer ring (607), between which male and female locking structure the end of the restriction mechanism (500) is locked.

9. The soft muscle (1) according to claim 5, wherein the end connection (600) is made of a plastic material suitable for 3D printing.

10. A soft robotic drive system, comprising:

a pneumatic source;

The soft muscle (1) of any one of claims 5 to 9, wherein the lumen (400) is adapted to be inflated by a gas; and

A control valve for controlling the flow direction and the flow rate of the gas.

11. A soft robotic drive system, comprising:

A hydraulic source;

The soft muscle (1) of any one of claims 5 to 9, wherein the lumen (400) is adapted to be inflated by a liquid; and

A control valve for controlling the flow direction and the flow rate of the liquid.

12. A robotic system comprising a plurality of the soft robotic drive systems of claim 10 or a plurality of the soft robotic drive systems of claim 11, wherein at least a portion of the soft robotic drive systems are controlled by a common control valve.

13. A robotic system comprising a plurality of the soft robotic drive systems of claim 10 or a plurality of the soft robotic drive systems of claim 11, wherein each soft robotic drive system is controlled by an independent control valve.