Flexible robot actuator, apparatus, system and method thereof

Abstract

One embodiment provides a flexible robotic actuator for assisting a body part of a subject. The flexible robotic actuator includes a flexible body and at least one chamber. The flexible body has a first side and a second side opposite the first side, and includes a patterned segment on the first side. The at least one chamber is defined by the flexible body and operably driven by a pressurized fluid such that the flexible body bends toward the patterned section and the bending angle of the flexible body is limited by the patterned section.

Description

[0001] Citation to Related Applications

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 370,402, filed on August 4, 2022, entitled “Soft Robotic Actuator for Upper Limb Rehabilitation,” the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present invention generally relates to a flexible robotic actuator, apparatus, system and method thereof for assisting a body part of a subject, such as a human being. Background Art

[0004] The following discussion of the prior art is intended to present the present invention in an appropriate technical context and to enable its advantages to be properly understood. However, unless otherwise expressly stated, reference to any prior art in this specification should not be interpreted as an explicit or implicit admission that such technology is well-known or forms part of the common general knowledge in the art.

[0005] Robotic devices have been widely adopted to assist objects such as humans. For example, robotic devices can assist in the rehabilitation of upper limb function, especially the rehabilitation of hand and wrist function. For example, spasticity is a medical condition characterized by excessive muscle tension, which affects the natural movement of body joints after stroke. Potential solutions for assisting the movement of spastic joints such as fingers or wrists after stroke have emerged in the field of wearable robots. These robotic devices or robots are designed to overcome joint spasticity and provide direct assistance for the movement of fingers and wrists. Most of these hand and wrist robots are constructed using high-power motors and rigid metal frames, which are bulky, difficult to further reduce the weight, and may be dangerous to patients due to excessive power. These devices are also mainly developed for laboratory environments. They are bound to huge power sources and therefore become bulky and unattractive when used outside of clinics or laboratories. Therefore, there is a need in the robotics industry to provide advantages in interacting with objects and assisting the function of a certain body part of the object.

[0006] It is an object of the present invention to overcome or substantially alleviate one or more disadvantages of the prior art, or at least provide a useful alternative. Summary of the invention

[0007] In one aspect of the present invention, a flexible robotic actuator for assisting a body part of a subject is provided. The flexible robotic actuator includes a soft body and at least one chamber. The soft body has a first side and a second side opposite the first side, and includes a patterned segment on the first side. The at least one chamber is defined by the soft body and is operably driven by a pressurized fluid so that the soft body bends in a first direction toward the patterned segment, and the bending angle of the soft body is limited by the patterned segment.

[0008] In another aspect of the present invention, a flexible robotic device for assisting a body part of an object is provided. According to one or more aspects of the present invention, the flexible robotic device includes a soft base wearable on a body part of an object and at least one flexible robotic actuator. The at least one flexible robotic actuator is configured to be fixed to the soft base. The soft base includes at least one fluid inlet and at least one data port, the fluid inlet is in fluid communication with the at least one chamber for receiving a pressurized fluid received from an external fluid source, and the data port is electrically connected to an external electrical system to monitor at least one parameter associated with the at least one flexible robotic actuator.

[0009] In another aspect of the present invention, a flexible robotic system for assisting a body part of an object is provided. The flexible robotic system includes a flexible robotic device and a control system. The flexible robotic device includes a soft base that can be worn on a body part of an object and at least one flexible robotic actuator configured to be fixed to the soft base. Each of the at least one flexible robotic actuator includes a soft body and at least one chamber defined by the soft body. The soft body includes a patterned segment on one side and is configured to be operably bent toward the patterned segment when the at least one chamber is driven by a pressurized fluid. The control system is fluidly connected to at least one chamber of each of the at least one flexible robotic actuator for controlling the injection of pressurized fluid into the at least one chamber, and is electrically connected to the flexible robotic device so that the operation of the at least one flexible robotic actuator is electrically controlled.

[0010] In another aspect of the present invention, a method for assisting a body part of an object is provided. The method includes: providing a flexible robotic device, the flexible robotic device including a soft base wearable on the body part of the object and a flexible robotic actuator, the flexible robotic actuator being fixed to the soft base, the flexible robotic actuator including a soft body and at least one chamber defined by the soft body, the soft body including a patterned segment on one side, and being provided with a plurality of annular constraints surrounding the at least one chamber, the plurality of annular constraints being provided with a plurality of anchoring structures on the other side of the soft body opposite to the aforementioned one side; and injecting a pressurized fluid into the at least one chamber so that the soft body bends toward the patterned segment, and the bending angle of the soft body is limited by the patterned segment.

[0011] Other exemplary implementations are discussed herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Embodiments of the present invention will now be described by way of example with reference to the accompanying drawings, in which:

[0013] Figure 1 A flexible robotic device including a flexible robotic actuator according to some embodiments of the present invention is shown, wherein the flexible robotic device is exemplified as a robotic wrist;

[0014] Figure 2A Shows Figure 1 A flexible robotic actuator, wherein the flexible robotic actuator is in a non-bent state;

[0015] Figure 2B The cross-sectional view shows Figure 2A The structure of the flexible robot actuator;

[0016] Figure 2C Shows Figure 2A A flexible robotic actuator, wherein the flexible robotic actuator is in a bent state;

[0017] Figure 3 shows the range of motion (ROM) characteristics of a flexible robotic actuator with respect to pressure-angle relationships according to certain embodiments of the present invention;

[0018] Figure 4A shows a flexed wrist of a patient suffering from spasticity according to some embodiments of the present invention;

[0019] Figure 4B Shows the Figure 4A A flexible robotic actuator with the wrist extended to a neutral position;

[0020] Figure 4CThe results show that when the flexible robot actuator is pressurized Figure 4A The wrist is fully extended;

[0021] Figure 5 A flexible robotic device including a flexible robotic actuator according to some embodiments of the present invention is shown, wherein the flexible robotic device is exemplified as a robotic hand;

[0022] Fig. 6A shows a finger actuator according to some embodiments of the present invention;

[0023] Figure 6B Shows the bending state when pressurized Fig. 6A The internal structure of the finger actuator;

[0024] Figure 6C Shown in extended state when pressurized Fig. 6A The internal structure of the finger actuator;

[0025] Figure 7 Shows Fig. 6A ROM characteristics of the finger actuator in the flexed state with respect to the pressure-angle relationship;

[0026] Figure 8 Shows Fig. 6A ROM characteristics of the finger actuator in the extended state with respect to the pressure-angle relationship;

[0027] Fig. 9 shows the internal structure of a hand base of a robotic hand according to some embodiments of the present invention, the hand base having a clamping structure to secure the finger actuators in place;

[0028] Fig. 10A A control system of a flexible robotic system according to some embodiments of the present invention is shown;

[0029] Fig. 10B Shows Fig. 10A The internal configuration of the control system;

[0030] Fig.11 A flexed finger of a patient suffering from spasticity is shown;

[0031] Fig.12 shows a control scheme of a finger actuator depending on the severity of muscle spasm measured by the Modified Ashworth Scale (MAS) according to some embodiments of the present invention;

[0032] Fig.13 illustrates calibration of a subject's joint motion intent according to certain embodiments of the present invention;

[0033] Fig.14shows measuring joint angle using a thin film flexion sensor according to some embodiments of the present invention;

[0034] Fig.15 A method of using an electric current to assist in the extension of a subject's wrist or fingers is shown;

[0035] Fig.16A Soft actuators according to certain embodiments of the present invention are shown;

[0036] Fig. 16B Shows Fig.16A A separate actuation chamber of a soft actuator;

[0037] Fig. 16C Shows Fig.16A An exploded view of a soft actuator;

[0038] Fig.17A A flexible robotic system according to some embodiments of the present invention is shown, wherein the flexible robotic system comprises a flexible robotic device and a control box, and the flexible robotic device is exemplified as a robotic hand;

[0039] Fig. 17B Shows Fig.17A An exploded view of the robot hand;

[0040] Fig. 17C Shows Fig.17A Configuration of the control box;

[0041] Fig.17D Shown for Fig.17A The control logic of the robot hand to facilitate the closing and opening movement of the hand;

[0042] Fig.18A shows free space bending of a finite element method (FEM) simulated soft actuator at a pressure input of 300 kPa according to some embodiments of the present invention;

[0043] Fig.18B shows a FEM simulated contact force bending of a soft actuator when the soft actuator is in contact with an object at a pressure input of 300 kPa according to some embodiments of the present invention;

[0044] Fig.19A shows an exemplary apparatus for actuator characterization regarding free-space bending of a soft actuator according to certain embodiments of the present invention;

[0045] Fig.19B An exemplary apparatus for actuator characterization regarding contact force bending of a soft actuator according to certain embodiments of the present invention is shown;

[0046] Fig. 20Dimensions of a soft actuator according to some embodiments of the present invention and the torque generated about a pivot point O at the tip of the soft actuator in a bent state during free space bending and contact with an object for the purpose of actuator modeling are shown;

[0047] Fig.21A shows the pressure-angle relationship of soft actuators for the index finger, middle finger, and ring finger according to some embodiments of the present invention;

[0048] Fig.21B shows the pressure-angle relationship of a soft actuator for a little finger according to some embodiments of the present invention;

[0049] Fig. 21C shows the pressure-angle relationship for a soft actuator of the thumb according to some embodiments of the present invention;

[0050] Fig.22A Three soft actuators with chamber lengths of 80 mm, 60 mm, and 40 mm, respectively, are shown;

[0051] Fig. 22B A 10 degree angular position relative to the proximal end of the soft actuator is shown;

[0052] Fig. 22C A 40 degree angular position relative to the proximal end of the soft actuator is shown;

[0053] Fig.22D Shows Fig.21A Pressure-force relationship of the three soft actuators at an angle of 10 degrees;

[0054] Fig.22E Shows Fig.21A The pressure-force relationship of the three soft actuators at an angle of 40 degrees;

[0055] Fig.23A shows actuator tip force during index finger gripping of a card according to certain embodiments of the present invention;

[0056] Fig. 23B shows the actuator tip force during index finger gripping of a wooden box according to certain embodiments of the present invention;

[0057] Fig.24A An equivalent model of a soft actuator for analyzing gripping forces at a metacarpophalangeal (MCP) joint and a proximal interphalangeal (PIP) joint, respectively, according to some embodiments of the present invention is shown;

[0058] Fig. 24B Estimated grip forces and measured joint angles during palmar grasp of a bottle are shown;

[0059] Fig.24C Estimated grip forces and measured joint angles during fingertip pen grasping are shown. DETAILED DESCRIPTION

[0060] The present invention will now be described with reference to the following examples, which are to be considered in all respects as illustrative and not restrictive. In the accompanying drawings, corresponding features within the same embodiment or common to different embodiments are given the same or similar reference numerals.

[0061] Throughout the specification and claims, the word "comprise" and its grammatical variations should be interpreted in an inclusive sense, rather than an exclusive or exhaustive sense; that is, in the sense of "including but not limited to".

[0062] In addition, unless otherwise specified, ordinal adjectives "first," "second," etc. used in this document to describe common objects merely refer to different instances of the same object and do not mean that the objects so described must be in a given order in time, space, order, or in any other way.

[0063] Exemplary embodiments relate to a flexible robotic actuator, device, system and method thereof for assisting a body part of an object. The object may be a human (e.g., a patient) or an animal (e.g., a pet, such as a dog or a cat). The body part of the object may be an upper limb (e.g., a wrist or hand) or other part (e.g., a leg, a foot). The body part may be damaged due to various reasons, such as trauma, incomplete spinal cord injury, stroke, multiple sclerosis, muscular dystrophy or cerebral palsy. Therefore, the body part may require medical rehabilitation or assistance to restore some or all of its function. The body part may not be damaged, but it is still preferred to provide it with some assistance so that it can function as desired.

[0064] Many existing systems have various disadvantages, such as being bulky, not portable, not suitable for the subject, having unsatisfactory service life, and uncontrollable output control of the subject's joints. For example, many existing medical rehabilitation systems include heavy, bulky motors. In addition, for example, existing robotic hands lack a mathematical method to quantify the gripping force generated to better control the grip of an object during activities of daily living (ADL).

[0065] Exemplary embodiments address one or more of these problems associated with existing systems and provide technical solutions with new designs. According to one or more embodiments, the movement of a subject's body parts (e.g., fingers and wrists) is controlled by one or more flexible robotic actuators that are driven by a pressurized fluid rather than an electric motor, which enables a more lightweight and compact design. The pressurized fluid can be air, gas, or liquid, such as water or a heavy oil-based hydraulic fluid (glycol ethers, organophosphates, poly-alpha-olefins, propylene glycol, or silicone oil, etc.).

[0066] One or more embodiments provide a lightweight, portable, soft robotic actuator that conforms to human tissue. The conformity between the actuator and human tissue minimizes harm to humans (e.g., patients). For example, a portable device incorporating a soft robotic actuator may allow a patient to wear it like a normal wristband on the wrist, which is not available with existing cumbersome laboratory-based devices.

[0067] One or more embodiments provide a flexible robotic actuator, device, or system that reduces the size of a traditional exoskeleton from a huge size to a size consistent with that of a human and can satisfactorily restore the function (e.g., flexion, extension, etc.) of a body part (e.g., a finger, wrist, leg, foot, etc.) during rehabilitation training.

[0068] One or more embodiments provide a muscle stimulator that can be applied to muscles to enhance muscle capabilities that are not available in existing rehabilitation exoskeletons. For example, the muscle stimulator can stimulate the upper limbs to promote better movement. In some embodiments, an electric current is generated as a muscle stimulator.

[0069] One or more embodiments provide a soft wearable robotic hand that actively controls finger flexion and extension through an elastomer-based bidirectional soft actuator. The actuator flexes and extends through pneumatic actuation at a relatively low air pressure, and a flexion sensor embedded in the actuator measures the angle of the finger in real time. The robotic hand facilitates the wearer to open and close the hand and successfully assists in grasping objects with sufficient force to complete tasks related to ADL.

[0070] Please refer to Figure 1 , 2A , 2B and 2C, a flexible robotic device is exemplified as a robotic wrist 30, which includes a flexible robotic actuator 10. The robotic wrist 30 can be worn on the wrist of an object to assist wrist movement. The object can be a person, such as a patient with a wrist injury and requiring assistance.

[0071] The robot wrist 30 can be worn on a human wrist 34 via a wristband 31. The wristband 31 forms a part of a soft base 30a, which can have various mechanical and / or electrical characteristics. The wristband 31 can be made of one or more materials, such as titanium alloy, nylon, plastic or carbon fiber composite material, so that the wristband 31 can be properly worn on a human wrist 34. The soft base 30a can be provided with at least one fluid inlet 33 and at least one data port 32, the fluid inlet 33 is used to receive fluid from an external fluid source, and the data port 32 is electrically connected to an external electrical system, so that the state of the robot wrist 30 can be monitored and / or the operation of the robot wrist 30 can be controlled.

[0072] The flexible robotic actuator 10 includes a soft body 10a and at least one chamber 15 defined by the soft body 10a. The soft body 10a has a first side or first face 10a-1 and a second side or face second 10a-2 opposite to the first side 10a-1. The soft body 10a includes a patterned segment 12 arranged on the first side 10a-1. The patterned segment 12 may have a zigzag or wavy or toothed pattern.

[0073] The soft body 10a has a first end 10-1 and a second end 10-2. The soft body 10a can be formed as an elongated body, and its longitudinal axis is parallel to the direction extending from the first end 10-1 to the second end 10-2. The soft body 10a is deformable. For example, when the soft body 10a is actuated or driven, the soft body 10a can be bent.

[0074] The chamber 15 is configured to be operably driven by a pressurized fluid so that the soft body 10a is as Figure 2C As shown, the flexible body 10a is bent toward the patterned segment 12 (the bending direction may be referred to as a first direction), and the bending angle of the flexible body 10a is limited by the patterned segment 12. For example, the channel 18 ( Figure 2B ) pressurized fluid, such as air, is injected into the chamber 15. A regulator 17 may be provided to regulate the channel 18. The regulator 17 may control the opening or closing of the channel 18, thereby allowing or prohibiting the fluid from flowing there. The regulator 17 may adjust the cross-sectional area of ​​the channel 18, thereby adjusting the flow rate in the channel 18. The regulator 17 may be appropriately designed, for example, including a valve and a knob for operating the valve. As a result, the pressure in the chamber 15 may be adjusted by the regulator 17, thereby adjusting the bending moment applied to the soft body 10a.

[0075] A plurality of annular restraints 13 (e.g., arranged on or embedded in the soft body 10a) can be provided for the soft body 10a and surround the chamber 15 to limit the axial expansion of the chamber 15 when the chamber 15 is driven by a pressurized fluid. For example, the rigidity of the annular restraint 13 can be higher than that of the soft body 10a, thereby enhancing the restraint effect. For example, the soft body 10a can be made of one or more materials that are easy to bend and can undergo the desired deformation, such as rubber, silicone, plastic, paper, etc. The annular restraint 13 can be made of one or more materials that are light in weight and difficult to be destroyed by the fluid pressure in the chamber 15 when pressurized, such as titanium alloy, nylon, plastic or carbon fiber composite material, etc.

[0076] Stiffness can be measured by elastic modulus and hardness. The elastic modulus and hardness of the annular restraint 13 can be much greater than the elastic modulus and hardness of the soft body 10a. For example, when the annular restraint 13 is made of metal, its elastic modulus is generally greater than 100GPa (e.g., steel: about 200GPa; titanium: about 110GPa; aluminum: about 69GPa; nickel: about 210GPa; iron: about 170GPa; molybdenum: about 330GPa). When the annular restraint 13 is made of plastic, its elastic modulus is generally approximately equal to or less than 10GPa (e.g., epoxy resin: about 5GPa; polyester resin: about 3.3GPa; phenolic resin: about 9GPa). The material used to make the soft body 10a can be an elastomer, whose elastic modulus is generally nonlinear or less than 10MPa (i.e., less than 0.01GPa), or even less than 100kPa (i.e., less than 0.1MPa).

[0077] In addition, a plurality of annular restraints 13 may be provided with a plurality of anchoring structures 11 on the second side 10a-2 for limiting the bending of the soft body 10a toward a second direction opposite to the first direction. The anchoring structure 11 may be made of one or more rigid materials. In some embodiments, due to the patterned segments 12 and the anchoring structures 11, the bending angle of the soft body 10a may be substantially limited to a range of 0 to 90 degrees. For example, when the flexible robot actuator 10 reaches zero degrees (i.e., the soft body 10a is straight and not bent), the anchoring structures 11 are tightly closed and pressed against each other. When the flexible robot actuator 10 attempts to bend to less than zero degrees, the legs of the anchoring structures 11 collide with each other, which limits the axial deformation of the chamber 15, thereby preventing the bending angle from being less than zero degrees. The patterned segments 12 are designed to be fully compressed when the bending angle of the soft body 10a is 90 degrees, thereby preventing any further bending. 90 degrees is an exemplary bending angle specially set for some applications, such as in the case of wrists and hands, because the range of motion of wrists and various finger joints usually does not exceed 90 degrees. It should be understood that the patterned segment 12 can be designed to allow the flexible body 10a to bend at an angle greater than 90 degrees.

[0078] A plate member 16 can be embedded in the soft body 10a and arranged between the patterned segment 12 and the chamber 15 to facilitate the bending of the soft body 10a. The plate member 16 can have a thickness of less than 1 mm. The plate member 16 can be made of one or more materials, such as plastic, metal or paper. For example, when the chamber 15 expands, the annular constraint 13 will limit the radial expansion of the chamber 15 and only allow axial elongation to occur. The plate member 16 will further limit the axial elongation at the area around the plate member 16. Finally, when the chamber 15 is inflated, the flexible robot actuator 10 undergoes an enhanced bending motion toward the patterned segment 12.

[0079] like Figure 2C As shown, an elastic sleeve 14 may be provided to surround at least a portion of the soft body 10a to improve the fixation of the annular constraint 13 on the soft body 10a. For example, the elastic sleeve 14 may cover the outer peripheral surface of the soft body 10a to fix the annular constraint 13 in place. This can avoid or reduce the undesirable displacement of the annular constraint 13 over time.

[0080] Preferably, the hardness of elastic sleeve 14 is much smaller than the hardness of soft body 10a, so that elastic sleeve 14 adapts to the deformation of soft body 10a. In this way, the covering of elastic sleeve 14 can not significantly increase the rigidity of soft body 10a, thereby avoids hindering the deformation (such as bending) of soft body 10a when fluid is injected into chamber 15. Elastic sleeve 14 can be made of one or more materials that are pliable and can withstand large deformation, such as rubber, silicone, plastics or paper. When elastic sleeve 14 is elastomer, its elongation at break value can be greater than 300%. The hardness of soft body 10a and elastic sleeve 14 can be but not limited to Shaw 00-10,20,30,40 and 50 or Shaw A-10,20,30,40,50,60,70,80 and 90.

[0081] Please refer to Figure 3 , which shows the range of motion (ROM) characteristics of the flexible robotic actuator 10 with respect to the pressure-angle relationship. ROM refers to the extent or limit to which a part of the body can move around a joint or fixed point. In this embodiment, when the chamber 15 is at a fluid pressure P 3 When actuated or driven, the ROM of the flexible robotic actuator 10 is limited to 0 degrees (0°) to θ max (90 degrees in this embodiment). The anchoring structure 11 prevents the flexible robotic actuator 10 from bending less than 0 degrees. At the same time, the shape and size of the patterned segment 12 are specifically designed to only allow the flexible robotic actuator 10 to bend a maximum of 90 degrees when the patterned segment 12 is fully folded. No matter how much pressure and / or external buckling the external force causes to the flexible robotic actuator 10, its ROM always remains within the specified range. However, it should be understood that this is for exemplary purposes only. In some embodiments, the flexible robotic actuator can be designed so that the bending angle can be less than 0 degrees or greater than 90 degrees.

[0082] Stroke patients often suffer from wrist contracture, which is mainly due to the weakening of the extensor digitorum (ED) muscles and the spasm of the flexor digitorum (FD) muscles. They have difficulty actively and voluntarily controlling their wrist extension movements. In stroke rehabilitation, restoring wrist extension ability is a prerequisite for restoring normal hand function, because the ED muscles are also crucial for finger extension movements. According to some embodiments, the robotic wrist 30 provides assistance to stroke patients to assist them in wrist extension.

[0083] Figure 4A , 4B4C show an example of a wearable robotic wrist 30 utilizing an exemplary soft robotic actuator 10 to extend a flexed human wrist 34. When the chamber 15 is filled with pressurized fluid, it will drive the soft body to bend, where the bending angle depends largely on the pressure within the chamber 15. The bending of the soft robotic actuator 10 will cause the human wrist 34 to move along, thereby achieving the natural function of the human wrist 34.

[0084] Specifically, if Figure 4B and 4C As shown, the orientation of the soft robotic actuator 10 is configured so that the anchoring structure 11 (not shown, on the side opposite to the patterned segment 12) faces the back side of the human wrist 34 on the proximal side, so that the patterned segment 12 is away from the human wrist 34. When the robotic wrist 30 is worn on the human wrist 34, the anchoring structure 11 can directly straighten the flexed human wrist 34 to keep it in a neutral position without relying on the pressurization of the soft robotic actuator 10. Once the pressurized fluid is applied to the chamber 15, the fluid pressure P in the chamber 15 is increased. 3 ( Figure 3 ) generates a bending force to directly extend the human wrist 34. Once the ROM is within the range of 0 to 90 degrees, the regulator 17 can adjust the fluid pressure P 3 To control the bending torque. When the soft body 10a is fully bent, that is, when the bending angle is 90 degrees, the flexible robot actuator 10 can thereby generate a maximum bending torque, for example, 5 Newton meters, as the average value of the human wrist extension torque. After the bending angle reaches 90 degrees, the fluid pressure P in the chamber 15 is 3 A further increase in the output torque can no longer increase the output torque.

[0085] Figure 5 A flexible robotic device according to some embodiments of the present invention is shown, where the flexible robotic device is exemplified as a robotic hand 100. The robotic hand 100 can be worn on a subject's hand to assist in the movement of the hand. The subject can be a person, such as a patient who has an injured hand and needs assistance.

[0086] In this embodiment, the robotic hand 100 includes a soft base or hand base 103 that can be worn on a subject's hand (e.g., a human hand). Two flexible robotic actuators 10 are connected in series to form a finger actuator 102, which is fixed to the hand base 103. Five finger actuators 102 are incorporated (e.g., mounted or installed) into the robotic hand 100 for controlling the thumb, index finger, middle finger, ring finger, and little finger, respectively. Similar to the robotic wrist 30, a fluid inlet 104 and a data port 105 are provided in the hand base 103 for delivering fluid to the finger actuator 102 through a channel 207 and communicating with an external electrical system, such as transmitting signals of bending angles measured by the flexible film angle sensor 205, respectively.

[0087] Each finger actuator 102 in this embodiment is shown as comprising two flexible robotic actuators 10 connected in series. This is for illustrative purposes only. It should be understood that in some embodiments, each finger actuator may consist of a single flexible robotic actuator, or may include three or more flexible robotic actuators, where these flexible robotic actuators may be connected in series, in parallel, or in a combination of series and parallel. A finger actuator is a collection of one or more flexible robotic actuators connected in a specified manner. In this sense, the finger actuator itself is a flexible robotic actuator or a collection of flexible robotic actuators.

[0088] Please refer to Fig. 6A , 6B , 6C, 7 and 8, which show the Figure 5 Detailed structure of the flexible robotic actuator 10 in the finger actuator 102 of the robot hand 100. The flexible robotic actuator 10 in the robot hand 100 has two chambers 208 and 209 for fluid injection. Each chamber is independently driven by a pressurized fluid. The chambers 208 and 209 are defined by two separate cavities 201 and 202, respectively. Similar to the robot wrist 30 described above, the chamber 209 is close to the patterned segment 12 and is used to limit the bending angle of the flexible robotic actuator 10. The chamber 208 is shown as having a regular shape with a height, width and length, of course, other shapes are also possible, and the chamber 208 is used to apply a fluid pressure P 1 When controlling the bending of the finger actuator 102 ( Figure 7 The chamber 209 has a corrugated shape with a height, a width and a length, although other shapes are possible, and the chamber 209 is used to apply a fluid pressure P 2 When controlling the extension of the finger actuator 102 ( Figure 8 In some embodiments, the stiffness of chamber 208 may be lower than that of chamber 209, so that a smaller pressure P 1 This is sufficient to bend the finger actuator 102, and greater pressure can be applied to extend the actuator.

[0089] To control the movement of the finger actuator 102, P 1 Pressurizing chamber 208 can facilitate bending toward chamber 209 to a 90 degree flexed position 298 ( Figure 6B ). On the other hand, using P 2 Pressurizing chamber 290 can facilitate extension toward chamber 208 to an extended position 299 of 0 degrees ( Figure 6C ). The annular restraint 203 uses the anchor structure 11 to limit further bending of the finger actuator 102 (i.e., less than 0 degrees, at Figure 7 and Figure 8201 is considered as positive in the counterclockwise direction). Therefore, two pressure sources can be applied to independently control the pressure inlets of chambers 208 and 209 through two fluid channels or pipes 207 (e.g., rubber tubes, PE tubes, PVC tubes, etc.). In the case where the stiffness of chamber 208 is lower than the stiffness of chamber 209, the pressure applied to chamber 201 is inherently lower than the pressure applied to chamber 202. A gap 204 with a height of no more than 1 mm is formed between chambers 208 and 209. An angle sensor 205 (e.g., SparkFun Electronic's 4.5" flexure sensor) and a plate member (e.g., polyethylene, nylon, etc.) having a thickness of no more than 1 mm may be arranged accordingly within the gap 204. The angle sensor 205 returns a resistance change to the external electrical system as an indication of the actuator angle change. The finger actuator 102 may be molded or 3D printed with an elastic material such as silicone, fabric, or the like. In the case where the stiffness of the chambers 208 and 209 is different, the finger actuator 102 may be designed by co-molding or direct 3D printing, which means that the chambers 208 and 209 may be adhered together without any additional assembly or gluing process to form a complete soft body.

[0090] Fig. 9 An exemplary internal structure of the hand base 103 is shown. The hand base 103 includes a control circuit 302 for transmitting signals generated by the angle sensor 205, an inlet port 104, a data port 105, and a clamping structure 305 that enables the finger actuator 102 to be tightly fixed to the hand base 103. The wearable hand base 103 includes a material that is biocompatible when in contact with a human hand.

[0091] refer to Fig. 10A and 10B A control system or module 101 is provided to communicate with a flexible robotic device (e.g., a robotic wrist or hand). The control system 101 is in fluid communication with at least one chamber of a flexible robotic actuator of the flexible robotic device so that pressurized fluid is injected into the chamber to deform the flexible robotic actuator. The control system 101 is also in electrical communication with the flexible robotic device so that the operation of the flexible robotic actuator is electrically controlled.

[0092] For example, the control system 101 includes a fluid pump 601 (the pressure output may be no greater than 600 kPa), a computer device 602 (e.g., a mini PC tablet (e.g., Raspberry PI)), a user interface or control panel 107, a power supply 108 (e.g., a portable power supply with an output voltage no greater than 24 V), a simulation device or current simulator 605, and a data acquisition device 606. The user interface 107 displays a control program for a user (e.g., a clinician) to control the use of a flexible robotic device (e.g., a robotic wrist 30 or a robotic hand 100). A fluid tube 104a and a data transmission cable 105a are used to connect the robotic hand 100 or the robotic wrist 30 to the control system 101 to supply fluid to the robotic hand 100 or the robotic wrist 30 and receive a bending angle signal through the flexible film angle sensor 205. An electrode cable 106 is also used to allow current to propagate from the simulation device 605 to human muscles, such as forearm muscles.

[0093] refer to Fig.11, wherein an impaired or disabled or flexed finger 501 (e.g., caused by a stroke) is shown, the finger 501 having a flexed metacarpophalangeal (MCP) joint 502, a proximal interphalangeal (PIP) joint 503, and a distal interphalangeal (DIP) joint 504. The finger actuator 102 can be fixed to the flexed finger 501. It is well known that muscle spasm is a major medical symptom (e.g., joint pain, tendon rupture, etc.) occurring in patients with impaired hand function, wherein the muscles become stiff or tight, thereby preventing normal fluid movement of body tissues. The muscles remain contracted and resist stretching, thereby affecting body joint movement. For patients with flexed fingers 501, the finger flexor muscles are in spasm, for which the muscles have contracted and generate resistance (or torque) 505 to resist the extension of the finger joints. Spasm is directly related to the rotation speed of the joint, and higher rotation speeds trigger greater resistance. At different rotation speeds, the torque 505 typically ranges from about 0.8 Newton meters to 1.7 Newton meters. When worn on a person's finger, the orientation of the finger actuator 102 is different from the orientation when the robotic wrist 30 is worn on a person's wrist 34. For the wearable robotic hand 100, the patterned segment 12 near the chamber 209 faces the back side of the finger 501 proximally. Provides bidirectional control for the finger, i.e., flexion and extension. Therefore, when the finger actuator 102 is fixed on a spastic finger by actuation, the amount of extension torque provided by the finger actuator 102 may depend largely on the elasticity of the soft body. When the chamber 209 is pressurized to 600 kPa, a maximum extension torque of 1 Newton·meter can be provided to balance the flexion torque 505 generated by muscle spasm of the finger joints when the hand is opened. When the chamber 209 is pressurized during extension, the speed of the finger actuator 102 is also controlled to 6 degrees / second. On the other hand, for patients with disabled fingers 501, it is uncommon for the finger extensor muscles to have spasticity, so the stiffness of chamber 208 may be less than the stiffness of chamber 209 used to control the spastic finger 501. When chamber 208 is pressurized to 300 kPa, the maximum flexion torque of finger actuator 102 may be 0.5 Newton-meter by default. When chamber 208 is pressurized during flexion, the speed of finger actuator 102 may also be controlled to be less than 6 degrees / second.

[0094] refer to Fig.12Depending on the severity of muscle spasticity as assessed by the clinician for each patient, the pressure output to the finger actuator 102 can be adjusted within the range of 0 kPa to 300 kPa for chamber 208 and 0 kPa to 600 kPa for chamber 209, so that the finger actuator can provide improved or even optimal extension torque to straighten the spastic finger 501. For an explanation of the pressure selection, please refer to the score of the Modified Ashworth Scale (MAS), which is a clinical assessment that grades the severity of spasticity, where Grade 0 = no increase in muscle tone; Grade 1 = slight increase in muscle tone at the end of ROM; Grade 1+ = slight increase in muscle tone within less than half of the ROM; Grade 2 = more significant increase in muscle tone within most of the ROM; Grade 3 = significant increase in muscle tone within most of the ROM; Grade 4 = complete stiffness of the affected joint.

[0095] In the case of MAS = 0, 1, 1+, since the muscle spasm is not obvious, that is, the flexion torque occurring in the finger joints due to muscle spasm is negligible, the flexion and extension of the spastic finger are allowed to be completely controlled by the chamber 208. When the finger actuator 102 is worn on the disabled hand 501, the finger flexion is controlled by pressurizing the finger actuator to 300 kPa with a 0.5 Newton meter bending torque provided. On the other hand, in the process of depressurizing the chamber 208 from 300 kPa to 0 kPa, the finger extension can be passively driven by the elasticity of the material. During the flexion and extension of the finger actuator 102, the chamber 209 can always be maintained in an unactuated state of 0 kPa.

[0096] In the case of MAS=2, since muscle spasm becomes obvious, that is, a significant flexion torque occurs in the finger joint due to muscle spasm, it is necessary to actuate two chambers 208 and 209. When the finger actuator 102 is worn on the disabled hand 501, the finger actuator is pressurized to 300 kPa with a flexion torque of 0.5 Newton meters provided to control finger flexion. On the other hand, chamber 209 is also pressurized to 300 kPa and a 0.5 Newton meter extension torque is provided to control finger extension.

[0097] In the case of MAS=3, since the muscle spasm becomes very severe, that is, a very strong flexion torque occurs in the finger joints due to muscle spasm, it is also necessary to actuate both chambers 208 and 209. When the finger actuator 102 is worn on the disabled hand 501, the finger actuator is pressurized to 300 kPa with a flexion torque of 0.5 Newton meters provided to control finger flexion. On the other hand, the chamber 209 is fully pressurized to a maximum of 600 kPa and an extension torque of 1 Newton meter is provided to control finger extension.

[0098] In case of MAS=4, since the finger joints become completely stiff in this case, it is impossible to control the flexion and extension of the spastic fingers no matter how the actuator 102 is adjusted. Therefore, the robotic hand 100 is not intended for patients diagnosed as MAS=4 by clinicians.

[0099] The control scheme for the robotic wrist 30 is relatively simple since only one-way control is required, ie wrist extension. The pressure applied to the chamber 15 is also regulated according to the level of the MAS.

[0100] In the case of MAS = 0, 1, 1+, a maximum pressure of 200 kPa is applied to control wrist extension, and a maximum torque of 1.7 N·m can be provided.

[0101] In the case of MAS=2, a maximum pressure of 400 kPa is applied to control wrist extension, and a maximum torque of 3.4 N·m can be provided.

[0102] In the case of MAS=level 3, a maximum pressure of 600 kPa is applied to control wrist extension, and a maximum torque of 5 N·m can be provided.

[0103] In case of MAS=4, since the wrist becomes completely rigid, it is impossible to extend the wrist regardless of pressurizing the chamber 15. Therefore, the robotic wrist 30 is also not intended for use on patients diagnosed as MAS=4 by a clinician.

[0104] The above description of various MAS scenarios is for exemplary purposes only, in order to illustrate certain applications of the flexible robot actuator or finger actuator according to one or more embodiments. Based on this description, various changes are possible.

[0105] Please refer to Fig.13 and 14 , an example of capturing the subject's intention can be based on an angle signal of an angle sensor 205 of a finger 700 or wrist 34. In this embodiment, the finger 700 is used as an example. The angle sensor 205 is placed in the finger actuator 102 to measure the angle change. The subject actively flexes a joint (e.g., finger 700) from an extended position 799 to a flexed position 798. The angle sensor 205 measures the change in the flexion angle during the movement. When the measured flexion angle is greater than a defined flexion threshold θ th-f (e.g., the flexion amplitude during maximum active contraction (MVC) θ max When the bending angle is less than the defined extension threshold θ, the finger actuator 102 bends. th-e (e.g., the flexion amplitude during maximum active contraction (MVC) θ max 80% of the original position), the finger actuator 102 extends.

[0106] In addition, for subjects who have difficulty extending their fingers or wrists, in order to assist in movement, the electrical muscle stimulator 605a provides current through the electrodes 106 attached to the forearm 109 to stimulate the contraction of the subject's forearm muscles 703 (e.g., the extensor digitorum), such as Fig.15 shown.

[0107] In order to further demonstrate the spirit of the present invention, the following will refer to Figures 16A-24C One or more soft actuators are described. The soft actuator may be a soft robotic actuator or a finger actuator as described above with reference to one or more embodiments, or one of their variations.

[0108] Please refer to Fig.16A , 16B 16C, the soft actuator 1602 includes a soft body 1602a and two chambers 1608 and 1609 defined by the soft body 1602a. For the purpose of description, the chamber 1608 may be referred to as a top chamber or a top cavity, and the chamber 1609 may be referred to as a bottom chamber or a bottom cavity.

[0109] In addition, an annular constraint 1613 surrounds or wraps the outer surface of the soft body 1602a to eliminate any irregular expansion of the chambers 1608 and 1609, thereby facilitating the flexion and extension of the soft actuator when the pressurized fluid is injected. An anchoring structure 1611 is arranged on the annular constraint 1613 on one side of the soft body 1602a. When the bottom chamber 1609 is pressurized, the anchoring structure 1611 helps limit overstretching to the top surface of the soft actuator 1602. A patterned segment (not shown) is provided on the opposite side of the soft body 1602a. A flexion sensor 1605 (e.g., a 4.5-inch angle sensor) is arranged in the soft body 1602a, and is preferably arranged between the two chambers 1608 and 1609 for measuring the bending angle of the soft body 1602a. Two retainers 1619 (e.g., Velcro retainers) facilitate the soft actuator 1602 to be attached to a human hand.

[0110] The soft actuator 1602 is a bidirectional soft actuator because one chamber controls its flexion and the other chamber controls its extension. When the top chamber 1608 is pressurized, the soft actuator 1602 flexes toward the bottom chamber 1609, and vice versa when the bottom chamber 1609 is pressurized. Therefore, the pneumatic source can effectively control flexion and extension, resulting in a much greater ROM. The soft actuator 1602 inherits the advantages of being lightweight, safe, and having a lower inherent impedance than its electric counterpart.

[0111] Fig.17A , 17B17C shows a flexible robotic system 170 according to some embodiments of the present invention, wherein the flexible robotic system 170 includes a flexible robotic device exemplified as a robotic hand 1700 and a control box 1750. Fig.17D The control logic of the robotic hand 1700 is shown. The robotic hand 1700 may be the robotic hand 100 as described above according to one or more embodiments or one of its variations.

[0112] The robot hand 1700 includes five soft actuators 1702 and a soft base received in a housing, which is mainly composed of a shell 1712 and a bottom shell 1714 that can be assembled together. In some embodiments, the size of the soft actuator 1702 is 12 mm wide and 12 mm high. The length is 65 mm (for the thumb), 85 mm (for the little finger) or 105 mm (for the other three fingers). The size of the robot hand 1700 is 17 cm (length) × 10 cm (width) × 3 cm (height). The weights of the five soft actuators 1702 and the robot hand 1700 are 19 grams and 176 grams respectively. These parameters are for illustrative purposes only. The size and weight of the soft actuator 1702 and the robot hand 1700 can be designed differently according to actual needs.

[0113] The control box 1750 is used as a control system. It is provided with various pneumatic components, including a fluid pump 1754 (e.g., an air pump), a solenoid valve 1755, an air tube and a pressure sensor 1756, an LCD touch screen 1757, an emergency button 1758, and other electronic components for controlling the pressure supplied to the soft actuator 1702. The emergency button 1758 is mounted next to the control panel for immediately reducing the pressure of the soft actuator in the case of an emergency stop. The control box 1750 has a control panel 1752 operable to interact with the user, and various electrical connections 1753. The LCD touch screen 1757 presents the control panel 1752 to the user, allowing them to control the system without being connected to a computer. The control panel 1752 allows the user to manually select a mode of closing or opening the hand. A hand container 1751 is provided on the top of the control box 1750, which is configured to accommodate the robot hand 1700 for storage. This compact design makes the flexible robot system 170 more portable. The control box 1750 can be 3D printed, with dimensions of 30 cm (length) x 30 cm (width) x 21 cm (height) and a weight of 1.7 kg. These parameters are for exemplary purposes only. The size and weight of the control box 1750 can be designed differently according to actual needs.

[0114] The solenoid valve and the fluid source are opened or closed by the control signal to adjust the pressure supplied to the soft actuator 1702. The pressure sensor is used to monitor the pressure supplied to the soft actuator 1702. Please refer to Fig.17D, when the hand closing option is selected, the bottom layer of the soft actuator will be depressurized and the top layer will be pressurized for 5 seconds to inflate the chamber of each soft actuator, and vice versa when the hand opening is selected. Finally, the Raspberry PI records the measured joint angles and sends a control signal to the solenoid valve to control the soft actuator, and identifies the output force using its mathematical model. This is for example purposes only. The soft robotic system 170 can be designed to operate in other ways according to actual needs.

[0115] Fig.18A and 18B The free space bending and contact force bending of a FEM simulation of a soft actuator under a pressure input of 300 kPa according to certain embodiments are shown respectively. The unit is millimeter (mm).

[0116] In this embodiment, specifically, a three-dimensional FEM model is established for a bidirectional soft actuator using ANSYS Workbench 15. Static structural analysis is performed on the model to determine the bending angle and output force of the soft actuator under different input pressures. The setup of the model is essentially the same as that reported in previous work: Heung, KHL, Tong, RKY, Lau, ATH, and Li, Z. (2019a), "Robotic glove with soft elastic composite actuators for assisting daily life activities," Soft Robot, 6(2), 289-304, the entire contents of which are incorporated herein by reference. The only simplification made is that the pressure inlet is ignored and pressure is applied directly to the inner wall of the chamber. To ensure accurate results, three-dimensional 10-node tetrahedral structural solid elements (ANSYS element type SOLID187) are used for the soft body (in this embodiment, the elastomer) and the annular constraint, while three-dimensional 20-node structural solid elements (ANSYS element type SOLID186) are used for the thin film buckling sensor. A coefficient μ is used. 1 =75,449Pa and α 1 =5.836 was used to model the Dragon Skin 30. For the annular restraint and the flexible sensor (polyethylene was used in this simulation), the material properties were obtained directly from the ANSYS engineering data source. The simulation results are shown in Fig.18A and 18B shown.

[0117] Fig.19A and 19BAn exemplary apparatus for actuator characterization for free space bending and contact force bending of a soft actuator according to certain embodiments is shown, respectively. The apparatus includes an air pump 1954 (which is an example of a fluid pump), a fixture 1951, a pressure gauge 1953, a power supply 1955, a soft actuator 1952, an electronic scale 1956 displaying a force reading 1957, and various other electronic components and connections.

[0118] The bidirectional flexible actuator 1952 is supplied with air pressure by an air pump 1954 (in this embodiment, the air pump is a BTC diaphragm pump from Parker Hannifin Corporation of Ohio, USA), which is controlled by a pressure gauge 1953 (in this embodiment, the pressure gauge is a ZSE20C(F) from SMC Pneumatic of Tokyo, Japan) and a voltage regulator (in this embodiment, the voltage regulator is an IR2020-02BG from SMC Pneumatic of Tokyo, Japan). The voltage regulator can be manually adjusted to control the air pressure supplied to the flexible actuator 1952, and the pressure value is displayed on the screen of the pressure gauge 1953. The power supply 1955 is exemplified as a 12V voltage source that provides power to the system for operation.

[0119] refer to Fig. 20 , a mathematical model was established for the soft actuator, where a is the wall thickness of the chamber of the soft actuator, b is the height of the chamber, e is the width of the chamber, L is the length of the chamber, t is the thickness of the buckling sensor, and L tip is the length of the actuator tip. The model describes the relationship between the input pressure and the bending angle and the output force of the soft actuator. The model is static in nature and takes into account the effects of the drag forces generated by the flexure sensor and the soft body, as well as the bending moment generated by the fluid injected into the chamber to provide an accurate representation of the soft actuator.

[0120] When pressure is applied, the soft actuator undergoes a bending motion that depends on the pressure levels in the two separate chambers. Assuming the chambers are rectangular and without any cross-sectional deformation, the bending moment caused by the pressure applied to each chamber can be determined by the following formula.

[0121] M bend represents the moment that bends the actuator and can be expressed as

[0122]

[0123] M extend represents the torque that causes the actuator to extend and can be expressed as

[0124]

[0125] P bend and P extend represents the input pressure, and dz represents the differential of the height element in the z direction.

[0126] The bending of the soft actuator causes the soft body and the flexure sensor to resist the bending deformation and generate a bending moment in the direction opposite to the bending itself. In addition, in this embodiment, Dragon Skin 30 silicone rubber is used to construct the bidirectional soft actuator. This material can be described by the Ogden first-order hyperelastic model. The strain energy of this material is expressed as

[0127]

[0128] Material coefficient α 1 is the strain hardening exponent, μ is the small strain shear modulus. Based on the Ogden material model, the internal stress σ that resists the bending deformation of the soft actuator is bend and σ extend It can be expressed as

[0129]

[0130] Here, and

[0131] Here λ is the axial stretch along the length of the soft actuator in the x direction, so

[0132]

[0133]

[0134] M sensor Representing the moment of the buckling sensor, it can be expressed as

[0135] Here, EI is the bending stiffness of the buckling sensor, where E is the elastic modulus and I is the second moment of area. sensor is the length of the sensor. θ is the bending angle of the soft actuator. For example, the flexure sensor is a PE plastic film with a width of 6.35 mm and a length of 114.3 mm. Its elastic modulus and thickness are assumed to be 1 GPa and 1 mm.

[0136] When the proximal end of the soft actuator is firmly mounted, it will exert a force F when its distal end contacts an external object. tip This force is perpendicular to the bottom layer to maintain L tip The constant bending moment arm, L tip is the length of the actuator end relative to the fulcrum O. The applied torque can be expressed as

[0137] M tip =F tip ·L tip (9)

[0138] Here, it is assumed that the interaction of forces occurs at the ends of the soft actuator, and the deformation along the soft actuator due to the application of force is not considered. Finally, the response of the bending angle to the input pressure can be found by the moment balance achieved around the fulcrum O in the bend. The integral of the moment balance can be solved numerically. For free bending, M bend +M extend =M σbend -M σextend +M sensor (10)

[0139]

[0140] And f(θ)=M σbend -M σextend (12)

[0141] For contact objects with contact force, M bend +M extend =M σbend -M σextend +M sensor +M tip (13)

[0142]

[0143] And f(θ)=M σbend -M σextend (15)

[0144] Fig.21A , 21B 21C show the pressure-angle relationship of the soft actuator. The soft actuator is used for the index finger, middle finger and ring finger ( Fig.21A ), little finger ( Fig.21B ) and thumb( Fig. 21C ). Each of the accompanying drawings shows a Fig. 20 The analysis results of the mathematical model, FEM results and references used Fig.19A and 19B Experimental results of the experimental setup.

[0145] In these embodiments, the top bending chamber and the bottom extension chamber are subjected to pressures ranging from 0kPa to 300kPa in increments of 50kPa. The resulting bending angle is then compared with the bending angle predicted by the analytical model and FEM simulation. The flexion sensor minimizes the effect of gravity on the bending angle, thereby achieving accurate measurement. The maximum input pressure of the soft actuator is limited to 300kPa. It can be seen that the experimental results are well consistent with the analytical model and FEM simulation, indicating that at the same input pressure level, the bending angle increases with the length of the soft actuator. For example, the actuator corresponding to the index finger, middle finger and ring finger achieves a bending angle of 172°, while the FEM simulation predicts 164°, and the analytical model predicts 151°. When the extension chamber is also pressurized to 100kPa, the maximum difference between the experimental results and the analytical model is observed to be 34° in the bending of the soft actuator corresponding to the three fingers at 300kPa. The bidirectional soft actuator achieves actuator extension by a method different from the prior art methods, such as described in the article "Effects of a Soft Robotic Hand for Hand Rehabilitation in Chronic Stroke Survivors" published by Shi, XQ, Heung, HL, Tang, ZQ, Li, Z. and Tong, KY in 2021 on page 30(7) (105812) of the journal J. Stroke Cerebrovasc. Dis. However, according to one or more embodiments, the bidirectional soft actuator described herein is superior to the actuator of the prior art by providing a greater ROM with a smaller input pressure while maintaining control over the extension of the actuator. The actuator of the prior art cannot produce a large ROM without increasing the input pressure, which reduces its life and causes rupture. That is, according to one or more embodiments, the soft actuator described herein achieves improved durability.

[0146] refer to Fig.22A , 22B , 22C, 22D and 22E, which show the pressure-force relationship of the soft actuator with 10 degree and 40 degree angular positions.

[0147] The top bending chamber is subjected to pressures ranging from 0 kPa to 300 kPa in increments of 50 kPa. The resulting output forces are then compared to those predicted by the analytical model and finite element simulations. The bending angle of the soft actuator is recorded during the measurement and the soft actuator will continue to bend (bulge) when subjected to increasing input pressure while in contact with an object. This bulge affects the output force and should be taken into account. In addition, in order to calculate the output force of the actuator using the analytical model and equations (10) and (13), the bending angle of the soft actuator needs to be determined. In order to estimate the output force at the end of the actuator, the bending angle obtained from the FEM simulation is used in the model to calculate the analytical force when the actuator is under pressure and obstructed by an object placed at 10 and 40 degree angles, respectively.

[0148] For an angle position of 10 degrees relative to the proximal end, when a pressure of 300 kPa is applied, the soft actuator bulges when in contact with an object at bending angles of 30° (the actuator represents the three fingers, the FEM result is 24.9°), 34° (the actuator represents the little finger, the FEM result is 30.9°), and 16° (the actuator represents the thumb, the FEM result is 19.2°). The measured output forces are 2.45 Newtons (the actuator represents the three fingers, the FEM result is 2.13 Newtons, and the analysis result is 2.43 Newtons), 1.85 Newtons (the actuator represents the three fingers, the FEM result is 1.38 Newtons, and the analysis result is 2.03 Newtons), and 2.36 Newtons (the actuator represents the three fingers, the FEM result is 1.87 Newtons, and the analysis result is 2.63 Newtons). The maximum difference between the analytical and experimental results was observed to be 0.52 Newtons on the actuators corresponding to the three fingers when pressurized to 150 kPa at the 10 degree position. No wall rupture or air leakage was observed during the tip force measurements.

[0149] For a 40-degree angle position relative to the proximal end, when a pressure of 300 kPa is applied, the soft actuator bulges unnoticeably when in contact with an object at bending angles of 119° (the actuator represents the three fingers, and the FEM result is 103.9°), 95° (the actuator represents the little finger, and the FEM result is 85.9°), and 75° (the actuator represents the thumb, and the FEM result is 70.5°). The measured output forces are 1.02 Newtons (the actuator represents the three fingers, and the FEM result is 0.97 Newtons, and the analysis result is 1.24 Newtons), 0.50 Newtons (the actuator represents the three fingers, and the FEM result is 0.66 Newtons, and the analysis result is 1.05 Newtons), and 0.48 Newtons (the actuator represents the three fingers, and the FEM result is 0.62 Newtons, and the analysis result is 0.76 Newtons). When pressurized to 300 kPa, the maximum difference between the analytical and experimental results of 0.55 Newton was observed on the actuator corresponding to the little finger.

[0150] The experimental results show that the stability of the soft actuator during grasping is affected by the size of the grasped object. Specifically, the bulging effect decreases with increasing bending angle, especially when grasping smaller objects. When grasping larger objects, the force estimation results were found to be close to linear, but became more nonlinear with increasing object size and actuator length. It is worth noting that the maximum possible flexion angle of the finger is 180°, but a flexion angle of 137° is sufficient for more than 90% of daily functional activities (Hume et al., 1990). Previous studies have reported that normal hand grasping produces fingertip forces of approximately 0.25 Newtons-3.59 Newtons. Taking these factors into account, the output ROM and force from the soft actuator are considered sufficient to grasp and clamp most everyday objects, such as bottles and cups.

[0151] refer to Fig.23A and 23B , which respectively show the index finger holding the card ( Fig.23A ) and wooden box( Fig. 23B ) during the actuator end force.

[0152] The purpose of these tests was to evaluate the feasibility of using a soft robotic hand to assist in activities of daily living (ADL). The ability to grasp a card (10 cm long, 6 cm wide) and a wooden box (2.5×2.5×2.5 cm) without being worn on a human hand was tested. When pressurized, the bending angle of the soft actuator corresponding to the index finger was measured by a flexion sensor. The bending angle and the corresponding dimensions of the corresponding soft actuator were then substituted into a mathematical model based on formulas 13-15 to estimate the grasping force of the robotic hand when grasping an object. The robotic hand was manually controlled as an indicator of the object, and a constant pressure of 300 kPa was applied during each actuation step. When the soft actuator corresponding to the index finger was selected to evaluate the end force when pinching the object, it was estimated that the force of the index finger pinching the card and the wooden box at 300 kPa reached 0.285 Newtons and 1.05 Newtons, respectively. Therefore, it was found that the force of the soft actuator estimated by the mathematical model ( Fig.23A and 23B ) is consistent with previous studies that measured fingertip forces during object grasping, in the range of approximately 1 Newton-2 Newtons (see Yap, HK, Lim, JH, Nasrallah, F., Goh, JCH, and Yeow, RCH, 2015, "Soft Exoskeleton for Hand Assistance and Rehabilitation Applications Using Pneumatic Actuators with Variable Stiffness," pp. 4967-4972, presented at the IEEE International Conference on Robotics and Automation (ICRA), Seattle, WA, USA, May 2015). This validation test has demonstrated that the soft robotic hand is able to grasp objects with sufficient force for tasks related to ADL.

[0153] To further evaluate the effectiveness of the soft robotic hand, two healthy subjects (age: 28 years old, male; age: 26 years old, female) with intact hand function were recruited with informed consent. During the evaluation, the subjects were asked to remain relaxed to avoid affecting the bending performance of the actuator and to ensure the best estimation of the output force.

[0154] Please refer to Fig.24A , 24B 24C, in order to apply the analytical model based on Equations 13-15 to estimate the fingertip contact force during grasping an object, the torque of the finger joint is considered to affect the bending of the soft actuator when pressed. Assuming that the gap between the soft actuator and the finger is negligible, the kinematics of the finger can be expressed as M joint =k joint (θ rest -θ); θ<θ rest (16)

[0155] In this k joint is the finger joint stiffness, θ is the joint angle, θ restθ is the initial resting angle when no finger movement is applied. Since the muscle tension naturally existing in the finger flexor muscles (such as the flexor digitorum profundus) is greater than the muscle tension in the finger extensor muscles (such as the extensor digitorum digitorum), the human fingers tend to curl inward and remain in the flexed position (θ rest ).

[0156] The bidirectional soft actuator can be considered as consisting of two segments, namely, the MCP segment and the PIP segment ( Fig.24A ). During grasping of an object, when each segment of the soft actuator covers the MCP joint and the PIP joint, the bottom cavity within the soft actuator remains unpressurized.

[0157] Regarding the MCP segment, when touching an object, M MCP _ bend =Mσ MCPbend -M σMCP_extend +M MCP_sensor +M MCP_tip -M MCP_joint (17)

[0158]

[0159] And f(θ)=M σMCP_bend -M σMCP_extend (19)

[0160] For the PIP segment, when touching an object, M PIP_bend =M σPIP_bend -M σPIP_extend +M PIP_sensor +M PIP_tip -M PIP_joint (20)

[0161]

[0162] And f(θ)=M σPIP_bend -M σPIP_extend (twenty two)

[0163] In the experiment, the soft actuator corresponding to the index finger was selected for preliminary evaluation of grip force estimation based on modeling equations 17-22. The bending angles of the MCP and PIP segments were measured by flexion sensors when pressurized. For the male subject (hereafter referred to as “S1”), θ MCP_rest =46°, and θ PIP_rest =40°. For the female subject (hereinafter referred to as "S2"), θ MCP_rest =58°, and θ PIP_rest =49°. For both subjects, K MCP_joint =0.01876, and K PIP_joint= 0.01533. The robotic hand was manually controlled as an indicator of the subject, and a constant pressure of 300 kPa was applied during each actuation step. The subjects were further assigned unilateral tasks involving palm grasping of a bottle (9 × 7 × 15 cm) and fingertip grasping of a pen (1 cm radius, 14 cm length). Two subjects successfully completed both tasks while wearing the robotic hand ( Fig. 24B and 24C ). No active and voluntary flexion and extension movements of the fingers were allowed throughout the process. From the results of grasping the bottle, before the robot hand was actuated, estimated grasping forces of 0.15 Newtons and 0.29 Newtons (S1) and 0.25 Newtons and 0.18 Newtons (S2) naturally existed at the MCP and PIP joint positions. When they put their hands on the bottle, they naturally grasped the bottle even without any active movement due to the natural contraction of the finger flexors. When a maximum pressure of 300kPa was applied, estimated grasping forces of 2.88 Newtons and 2.96 Newtons (S1) and 3.25 Newtons and 3.13 Newtons (S2) were obtained. On the other hand, since the MCP joint is not involved at all during fingertip grasping, only the grasping force at the PIP joint position is considered when grasping the pen. When the input pressure reaches 100kPa, the soft actuator causes the index finger of S2 that touches the pen to flex, and the same is true for S1 at 150kPa. At an input pressure of 300 kPa, the maximum clamping forces are estimated to be 1.64 Newtons (S1) and 1.89 Newtons (S2). Note that at the same input pressure, the auxiliary gripping force is not constant and depends on the size of the object. To grasp the object, a smaller size would require a larger actuator bending angle to bend the fingers to the position of the object, which directly reduces the output force provided for grasping smaller objects.

[0164] As used anywhere herein, modifying an object with the terms "soft" or "flexible" means that the object is substantially composed of a compliant material, rather than being composed of a rigid material.

[0165] It should also be understood that any features in the above-mentioned embodiments of the present invention can be combined together and do not necessarily have to be applied in isolation from each other. It is easy for those skilled in the art to carry out similar combinations of two or more features of the above-mentioned embodiments or preferred forms of the present invention.

[0166] Unless otherwise specified, all technical and scientific terms used in this article have the common meanings commonly understood by those skilled in the art to which the exemplary embodiments belong. The embodiments are illustrated by non-limiting examples. Based on the embodiments disclosed above, various modifications that can be thought of by those skilled in the art should be within the spirit of the exemplary embodiments.

Claims

1. A flexible robotic actuator for assisting a body part of a subject, the flexible robotic actuator comprising: a flexible body having a first side and a second side opposite the first side, the flexible body including patterned segments on the first side; and At least one chamber is defined by the soft body and is operably driven by a pressurized fluid so that the soft body bends in a first direction toward the patterned segment, and the bending angle of the soft body is limited by the patterned segment. 2 . The flexible robotic actuator of claim 1 , wherein the patterned segment has a zigzag pattern.

3. The flexible robotic actuator according to claim 1 or claim 2 further includes a plurality of annular restraints provided for the soft body, the annular restraints surrounding the at least one chamber, for limiting the axial expansion of the at least one chamber when the at least one chamber is driven by the pressurized fluid.

4. The flexible robotic actuator according to claim 3, wherein the stiffness of the plurality of annular constraints is higher than the stiffness of the soft body, and the plurality of annular constraints are made of one or more materials selected from the group consisting of titanium alloy, nylon, plastic and carbon fiber composite materials.

5. A flexible robotic actuator according to claim 3 or claim 4, wherein the plurality of annular restraints are provided with a plurality of anchoring structures on the second side of the soft body, and the plurality of anchoring structures are used to limit the bending of the soft body toward a second direction opposite to the first direction.

6. The flexible robotic actuator according to any one of the preceding claims, wherein a bending angle of the soft body is in the range of 0 to 90 degrees.

7. The flexible robotic actuator according to any one of the preceding claims, further comprising a plate member embedded in the soft body and arranged between the patterned segment and the at least one chamber, for assisting the soft body in bending toward the patterned segment.

8. The flexible robotic actuator according to claim 7, wherein the plate member has a thickness of less than 1 mm.

9. The flexible robotic actuator according to claim 7 or claim 8, wherein the plate member is made of one or more materials selected from the group consisting of plastic, metal and paper.

10. The flexible robotic actuator according to any one of claims 3 to 5, further comprising an elastic sleeve for surrounding at least a portion of the soft body along a longitudinal direction of the soft body to improve fixation of the plurality of annular restraints on the soft body. 11 . The flexible robotic actuator according to claim 10 , wherein the hardness of the elastic sleeve is smaller than the hardness of the soft body, so that the elastic sleeve adapts to the deformation of the soft body.

12. The flexible robotic actuator of any one of the preceding claims, wherein the at least one chamber comprises a first chamber and a second chamber, each chamber being independently driven by the pressurized fluid.

13. The flexible robotic actuator of claim 12, wherein the first chamber is operably driven to generate a bending force applied to the body part of the subject, and the second chamber is operably driven to generate an extension force applied to the body part.

14. The flexible robotic actuator of claim 13, wherein the bending force and the extension force are configured to control flexion and extension of a proximal interphalangeal (PIP) joint and a metacarpophalangeal (MCP) joint of the subject, respectively.

15. The flexible robotic actuator according to any one of the preceding claims, further comprising an angle sensor configured to measure a bending angle of the soft body.

16. The flexible robotic actuator of claim 15, wherein the angle sensor is a flexible thin film flexure sensor extending along a longitudinal axis of the soft body.

17. A flexible robotic actuator according to any one of the preceding claims, wherein the soft body is an elastomer.

18. A flexible robotic device for assisting a body part of a subject, comprising: a flexible base capable of being worn on a body part of the subject; and At least one flexible robotic actuator according to any one of claims 1 to 17, Wherein the at least one flexible robotic actuator is configured to be fixed to the soft base, and the soft base includes at least one fluid inlet and at least one data port, the at least one fluid inlet is connected to the at least one chamber fluid for receiving pressurized fluid from an external fluid source, and the at least one data port is electrically connected to an external electrical system so that at least one parameter associated with the at least one flexible robotic actuator is monitored.

19. The flexible robotic device of claim 18, wherein the at least one parameter comprises a bending angle of the at least one flexible robotic actuator.

20. A flexible robotic device according to claim 18 or claim 19, wherein the flexible robotic device is a robotic wrist and the soft base comprises a wrist strap for wrapping around the subject's wrist.

21. A flexible robotic device according to claim 18 or claim 19, wherein the flexible robotic device is a robotic hand.

22. The flexible robotic device of claim 21, wherein the at least one flexible robotic actuator forms five finger actuators, each finger actuator being configured for a corresponding finger of the object.

23. The soft robotic device of claim 22, wherein each of the five finger actuators comprises two soft robotic actuators connected in series.

24. The flexible robotic device of claim 22 or claim 23, wherein each of the five finger actuators comprises a first chamber and a second chamber, each chamber being independently driven by the pressurized fluid, The first chamber is operably driven to generate a bending force applied to the corresponding finger, and the second chamber is operably driven to generate an extension force applied to the corresponding finger.

25. The flexible robotic device according to claim 24, wherein each of the five finger actuators is provided with a flexion sensor, which is arranged between the first chamber and the second chamber for measuring the bending angle of the corresponding finger actuator.

26. A flexible robotic system for assisting a body part of a subject, comprising: a flexible robotic device comprising a soft base wearable on a body part of the subject and at least one flexible robotic actuator configured to be secured to the soft base, each of the at least one flexible robotic actuator comprising a soft body and at least one chamber defined by the soft body, the soft body comprising a patterned segment on one side and configured to operably bend toward the patterned segment when the at least one chamber is driven by a pressurized fluid; and A control system, which is fluidly connected to the at least one chamber of each of the at least one flexible robotic actuator, is used to control the injection of the pressurized fluid into the at least one chamber, and is electrically connected to the flexible robotic device so that the operation of the at least one flexible robotic actuator is electrically controlled.

27. A flexible robotic system according to claim 26, wherein each of the at least one flexible robotic actuator includes an angle sensor, the angle sensor is configured to measure the bending angle of the soft body, and the control system is configured to receive an angle signal indicating the bending angle from the angle sensor.

28. The soft robotic system of claim 26 or claim 27, wherein the control system comprises a fluid pump and a solenoid valve configured to regulate the pressurized fluid entering the at least one chamber to deform the soft body.

29. The flexible robotic system of any one of claims 26 to 28, wherein the control system comprises an electrical muscle stimulator configured to generate an electrical current to a muscle of the subject.

30. The flexible robotic system of claim 29, wherein the electric current stimulates contraction of a forearm muscle of the subject.

31. A method for assisting a body part of a subject, the method comprising: A flexible robotic device is provided, the flexible robotic device comprising a soft base capable of being worn on a body part of the subject and a flexible robotic actuator, the flexible robotic actuator being fixed to the soft base, the flexible robotic actuator comprising a soft body and at least one chamber defined by the soft body, the soft body comprising patterned segments on one side and being provided with a plurality of annular restraints surrounding the at least one chamber, the plurality of annular restraints being provided with a plurality of anchoring structures on another side of the soft body opposite to the one side; as well as A pressurized fluid is injected into the at least one chamber, so that the soft body bends toward the patterned segment, and the bending angle of the soft body is limited by the patterned segment.

32. The method of claim 31 , further comprising controlling a pressure of the pressurized fluid within the at least one chamber by adjusting a flow rate of the pressurized fluid into the at least one chamber.

33. The method of claim 31 or claim 32, further comprising generating an electric current for stimulating a muscle of the subject.

34. The method of any one of claims 31 to 33, wherein the at least one chamber comprises a first chamber and a second chamber, and the method further comprises: actuating the first chamber with the pressurized fluid to generate a bending force applied to the subject's finger; as well as The second chamber is actuated by the pressurized fluid to generate an extension force on the subject's finger.

35. The method according to any one of claims 31 to 34, wherein providing the flexible robotic device comprises providing a robotic wrist or a robotic hand as the flexible robotic device.

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