Soft exoskeleton wearable device for temporomandibular joint disorder rehabilitation

Abstract

The present invention discloses an exoskeleton wearable device configured to push the condyle away from the temporal joint structure of the skull, with two bellows-shaped actuators each having an elliptical cross-section; an upper component configured to be mounted to the patient's forehead and serve as a base for the two bellows-shaped actuators; and a lower component configured to be mounted to the patient's mandible, the lower component being substantially immovable relative to the mandible but movable relative to the upper component in a horizontal plane and a vertical plane.

Description

Technical Field

[0001] The present invention discloses a wearable device for temporomandibular joint disorders and a method involved thereby. Background Art

[0002] Temporomandibular joint disorder (TMD) is a disease that affects an individual's temporomandibular joint (TMJ) and the muscles for jaw movement. Symptoms of temporomandibular joint disorder include limited movement and noise when the patient moves the jaw and severe pain. Patients with temporomandibular joint disorder have difficulty speaking and chewing food. This disease may be caused by dislocation of the temporomandibular joint or chewing muscles. It is reported that nearly 10 million people in the world suffer from temporomandibular joint disorder, and no appropriate treatment has been invented yet. It has been confirmed that irreversible treatment by means of medical implants is not effective and increases the possibility of causing more severe pain and permanent damage to the jaw.

[0003] The difficulty in treating temporomandibular joint disorder stems from the complexity of the temporomandibular joint, which includes rotation around a kinematic axis that also translates. When the jaw is slightly opened, the temporomandibular joint rotates almost exclusively, while a greater opening of the jaw is due to the translational movement of the temporomandibular joint. The combination of this rotational movement and sliding movement is difficult to reproduce with mechanical structures, especially the unique jaw sizes of different individuals are even more difficult to reproduce with mechanical structures.

[0004] In view of the urgent need for treating temporomandibular joint disorders, medical workers and researchers have proposed and manufactured various training devices. Due to the difficulty for patients to move their jaws to open and close the mouth, existing training devices focus more on helping patients open their restricted mouths by applying external forces. Early manual training was usually carried out with a joystick-based tool that only had movement in the vertical plane. More complex treatment devices have emerged recently and the simulation of human jaw movement has been studied. The single opening treatment with a rigid link does not conform to the real jaw movement trajectory, thus further causing pain and injury. A six-degree-of-freedom parallel mechanism that can reproduce the same movement range and force of the human jaw has been developed by simulating the hand movement of a doctor during mouth opening. For the purpose of practical training of the temporomandibular joint, a four-link helmet-based wearable device has been proposed, which uses motors and drive belts to reproduce the movement of the human jaw. In order to keep the mandible or teeth in the correct orientation on the chewing trajectory, two more links are added to form a six-link mechanism to propose a planned biting angle and speed. The conceptual design of a shoulder-mounted robotic exoskeleton for neuromuscular training of temporomandibular joint disorders has been proposed, which has a moving motor-driven joint and an intraoral plate for transferring force to the lower teeth to drive the mouth open. However, this method itself has an extremely large system and is not designed considering the best interests and comfort of the patients, thus having the following limitations: 1) The whole system is large, bulky and inconvenient for patients to wear, which restricts the convenience of training and rehabilitation. 2) The rigid mechanism has insufficient compliance, and its pre-planned movement is not suitable for each different individual, which will lead to safety problems and further injuries.

[0005] In most existing temporomandibular joint training devices, a more satisfactory method would be as light, safe and comfortable as possible and meet the needs of patients. Among them, the exoskeleton machine provides more convenience by using simulations for training, but the traditional motor-driven and link-based mechanism design has very limited compliance and adjustability in jaw movement output, thus restricting its application in temporomandibular joint training where safety and easy customization are required. Summary of the Invention

[0006] The following presents a brief overview of the present invention to provide a basic understanding of certain aspects of the present invention. This overview is not a high-level summary of the present invention. Its purpose is not to distinguish the main or key components of the present invention, nor to define the scope of the present invention. However, the purpose of this overview is to present certain concepts of the present invention in a simplified form as a prelude to the more detailed description presented later.

[0007] As described herein, the novel exoskeleton wearable device includes at least one of the following: 1) Utilizing soft robotics methods to achieve true human jaw movement, reducing the weight of the entire wearable machine and increasing safety and comfort; 2) Guiding the gliding movement of the jaw in the vertical plane while maintaining its compliance in the horizontal plane; 3) Considering specific temporomandibular joint characteristics for potential temporomandibular joint disorder treatment. In Figure 1 The proposed exoskeleton soft wearable device is shown. The proposed mechanism can achieve many features with appropriate design, which are widely used in robotic hands and bionic engineering based on compliant soft actuators. In these works, a systematic analysis and study of the dual-actuator soft joint are performed and verified through visual tracking both on the workbench and on the skull. The experimental results demonstrate the motion performance of the proposed soft exoskeleton wearable device and these studies are discussed in detail.

[0008] The exoskeleton wearable device disclosed herein is an exoskeleton wearable device configured to push the condyle away from the temporomandibular joint structure of the skull, including two bellows-shaped actuators each having an elliptical cross-section; an upper component configured to be mounted on the patient's forehead and serving as a base for the two bellows-shaped actuators; and a lower component configured to be mounted to the patient's mandible and the lower component is substantially stationary relative to the mandible but moves relative to the upper component in the horizontal and vertical planes.

[0009] The present invention also discloses a method for treating temporomandibular joint disorders, including attaching an exoskeleton wearable device to the patient's skull; and using the exoskeleton wearable device to facilitate at least one of the opening or closing movements of the patient's jaw.

[0010] To achieve the above and related technical problems, the present invention includes the technical features described in detail below and these technical features are particularly pointed out in the claims. The following description and drawings describe in detail various aspects and embodiments shown by the present invention. However, this only illustrates a part of the various embodiments in which the principles of the present invention can be employed. Other technical problems, technical advantages, and novel features to be solved by the present invention are presented through the following detailed description of the present invention in conjunction with the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 A side view (left) and a front view (right) of an exoskeleton soft device worn on a skull model according to an embodiment are shown.

[0012] Figure 2 The anatomical structure of the human chewing system is shown. The upper right shows the closed jaw, where the condyle is engaged with the temporomandibular joint structure. The lower right shows the open jaw, where the condyle slides out of the temporomandibular joint structure.

[0013] Figure 3 Show the main parameters of the soft robotic joint of the temporomandibular joint and the analysis model.

[0014] Figure 4 Show an embodiment of the control scheme of the soft robotic joint.

[0015] Figure 5 Show an embodiment of the pneumatic control platform.

[0016] Figure 6 Show an embodiment of the experimental platform. The left figure shows the desktop soft robotic joint unit test platform, which is equipped with two markers for collecting the actual trajectory and kinematic characterization of the movement. The right figure shows the test platform on the skull, which is equipped with a cylinder for driving the main movement of the jaw opening.

[0017] Figure 7 Show the lateral compliance experiment. A force is applied in the shown direction to test the displacement. There is no obvious difference when the actuator is actuated.

[0018] Table 1 records the structural and material parameters of the soft robotic joint according to an embodiment.

[0019] Figure 8 Show the test results of actuating only the upper actuator. The actual trajectory is compared with the calculated trajectory. Figure 8 a shows that the real trajectory angle fits well with the calculated trajectory angle, with a deviation of less than 1 mm. Figure 8 b shows the kinematic characterization, including velocity, acceleration, angular velocity, and angular acceleration. The steep slope shows the rapid response of the movement once the actuator is actuated.

[0020] Figure 9 Show the experimental results of actuating only the lower actuator. Figure 9 a shows the trajectory comparison and angle change. Figure 9 b shows the kinematic characterization.

[0021] Figure 10 Show the experimental results of actuating both actuators. Figure 10 a shows the trajectory comparison and angle change. The angle hardly changes during the actuation process. Figure 10 b shows the kinematic characterization. The angular velocity and angular acceleration oscillate within a very small range through calculation because the angle change value is approximately zero.

[0022] Figure 11 Show the test results of the trajectory simulation. Figure 11 a shows the pressure obtained by inverse solving through the displacement function. The actual pressure well follows the pressure calculated using the pneumatic platform. Figure 11b shows the trajectory comparison and angle change. The inclination angle of the actual trajectory well conforms to the designed inclination angle. Figure 11 c shows the kinematic characterization.

[0023] Figure 12 Shows the test results on the skull. Figure 12 a shows the trajectory comparison and angle change. The green circle magnifies the trajectory collected on the right side of the skull. The triangle shows the trajectory collected when the device is not actuated, while the dot shows the trajectory after actuation. The gray triangle and dot respectively show the same trend in the initial stage of actuation. The difference during actuation of the device is shown by the blue triangle and red dot. The end effector can significantly push the condyle away from the temporomandibular joint structure. The angle change curve shows that the movement is first rotational and then gliding. Figure 12 b shows the kinematic characterization. Detailed implementation

[0024] This article discloses rehabilitation using a soft approach not found in the prior art. The soft mechanism described herein has at least one of the following advantages:

[0025] 1. It takes into account the real temporomandibular joint mechanism;

[0026] 2. Lightweight, comfortable and safe;

[0027] 3. Natural compliance and will not cause further damage;

[0028] 4. Trajectory planning and customization;

[0029] Existing training devices for temporomandibular joint disorders are bulky and large, and the manufacturing does not consider the comfort and safety of patients. Their purpose is to forcibly drive the movement of the condyle. The present invention provides a lightweight and customizable device that uses a soft approach to help patients train and correct jaw movement at home by using a pneumatically controlled soft actuator, which is lightweight and conforms to individual differences. This article describes a wearable exoskeleton device with pneumatically controlled trajectory planning. This realizes the preliminary pneumatic control for actuating the device to reproduce human jaw movement. To optimize performance and customization, precise control using various payloads can be developed.

[0030] Cases of temporomandibular joint disorders require correct and sufficient guidance of the movement of the patient's mandible. The most ideal application is to use robotic devices for movement training in addition to surgical procedures performed by doctors. What is provided is a dual soft actuator robotic joint design applied to an exoskeleton soft wearable device with substantial improvements over existing training devices. Considering the comfort and safety of the patient, this soft device helps to significantly reduce the weight of the device and retain the compliance of the system, which brings optimal wearing performance and optimal self-training performance. Trajectory planning based on pneumatic control can customize the device to meet the purpose of adapting to individual patient differences.

[0031] The design, modeling, fabrication, and verification of an exoskeleton soft wearable device for temporomandibular joint disorders will be presented in detail below. Both the desktop unit and the tests on the skull can demonstrate its significant ability to guide the movement of the mandible according to real human physiology, opening up the way for further medical applications of such diseases.

[0032] Mandibular movement mechanism

[0033] The human chewing system has a developed structure capable of performing functions such as chewing, mixing, and swallowing food. As Figure 2 shown, the mandible achieves various movements by accommodating attachments of muscles and ligaments. Theoretically, due to the rigidity of the mandible, it is entirely possible to reconstruct the position using a single-point orientation and position. If the maxilla and mandible are properly aligned, the movement of the mandible can be known by understanding the position of the condyle of the temporomandibular joint.

[0034] The temporomandibular joint is a movable joint that can move between two bones and is composed of a series of bony and soft tissue components. The bony part includes the condyle of the mandible and the temporomandibular joint structure on the skull. This combination can effectively serve as a pivot point for multi-dimensional movement, such as the fulcrum of a lever and the guidance of the movement of the mandible. The soft tissue mainly includes the articular disc, which is a continuous structure located between the bony and articular surfaces of the temporomandibular joint.

[0035] This articular disc prevents collisions between multiple bony parts, and its movement also ensures the smooth movement of the condyle. Displacement of this articular disc can cause temporomandibular joint disorders, resulting in clicking sounds, synovitis, pain, and limited movement. With the protection of this articular disc, the condyle can rotate around the horizontal axis and slide along the articular tubercle. Due to the complex structure and movement mechanism of the temporomandibular joint, the true movement trajectory of the condyle is ignored in existing diagnostic and treatment machines. Mechanically and forcibly opening the patient's mouth can cause further damage to the condyle, articular disc, or the entire temporomandibular joint.

[0036] Soft robotic joint design for the temporomandibular joint

[0037] To ensure the training correction of jaw movement and avoid causing further damage, a dual soft actuator joint design provides exoskeleton support and actuates as the true temporomandibular joint movement trajectory. Using two combined pneumatic actuators, the proposed soft approach can reproduce the condylar movement trajectories of different individuals through pressure control. Compared with existing diagnostic and treatment equipment, this device is lighter in weight and more compliant to make patients feel comfortable and safe.

[0038] The soft actuator is selected as a well-studied corrugated tube and is installed at an angle compared with the traditional parallel structure to have inherent multiple degrees of freedom. In addition, due to deformation within the range of the transverse plane, an actuator with an elliptical cross-section is selected to bend more effectively than an actuator with a circular cross-section. Figure 3 An analytical model derived for studying the deformation and geometric relationships of the proposed joint is shown.

[0039] For the corrugated soft actuator, with the number of turns N, outer diameter / inner diameter ratio α, cross-sectional area S, Young's modulus E, wall thickness t, Poisson's ratio μ, and initial length l0, the length of the soft actuator after swelling is:

[0040]

[0041] where l0 is the tensile length of actuator 1, ky is the axial stiffness, and P1 is the internal pressure of actuator 1.

[0042] The torque that bends the actuator is:

[0043]

[0044] where M1 is the torque caused by the end effector, MP is the torque caused by the internal pressure of the actuator, and r is the simplified circular inner diameter of the elliptical actuator.

[0045] Next, according to the cantilever beam theory, the deformation function w1 of actuator 1 can be written as:

[0046]

[0047] where x1 is the position of the actuator on the x-axis, I x ellipse is the moment of inertia of the elliptical tube in the x-plane, and β = b / a is the parameter of the ellipse with semi-major axis a and semi-minor axis b.

[0048] The forces generated by the end effector on actuator 1 and actuator 2 can be expressed as f1 and f2, and there is the following relationship:

[0049] P1·S = f1·cosγ + f2 (4)

[0050] Since the two actuators are also connected to the end effector, there should be a geometric relationship:

[0051]

[0052] where γ is a preset end effector angle.

[0053] Apply the boundary conditions to the built-in end components and the above geometric relationship:

[0054]

[0055]

[0056]

[0057] where Δθ is the rotational angle of the end effector, and all integral constraints can be solved.

[0058] Therefore, the relationship between the displacement of the end effector and the internal pressure of the actuator can be derived: (dc, dy) = f(P1, P2). Solving this equation for the required displacements in the x and y directions gives the pressure commands for trajectory planning.

[0059] Design of an exoskeleton wearable device

[0060] The exoskeleton wearable device is connected by the proposed dual soft actuator robotic joint. Thus, the exoskeleton wearable device includes two lightweight and wearable main components, as Figure 1 shown. The upper component is mounted on the patient's head and designed as a thin ring. The ring is both soft and adjustable and serves as the base of the robotic joint. The upper component is fixed relative to the temporomandibular joint structure on the skull and serves as a reference point during movement. Then, the lower component is mounted to the mandible and is fixed relative to the mandible. When actuated, a force is applied to the mandible, and the strap connecting the left and right components is tightened against the patient's jaw. With the two wearable components connected by the soft robotic joint, the patient has support and movement during oral opening training with pneumatic control. Also for comfort, safety, and adjustability purposes, the exoskeleton device can be made of elastic material and a rubber-like gasket can be attached to the contact area with the patient's skin.

[0061] The entire device inherently possesses compliance within all degrees of freedom of movement, including those in the horizontal and vertical planes. This compliance ensures safety by allowing for tolerances that account for individual uniqueness, as the true movement trajectories of the human mandible are not simple back-and-forth curves within a single plane. Traditional training devices sacrifice this compliance, ignoring individual differences and the complexity of movement, which can cause further injury to patients during training. The device described herein uses a soft approach to allow for and accommodate individual differences while providing sufficient support to help push the condyles out of the temporal joints of the skull.

[0062] Control Scheme

[0063] To explore the impact of the proposed exoskeleton soft wearable device in temporomandibular joint disorder training, the system can be controlled and pressure command outputs can be precisely generated according to the desired movement trajectories. For the proposed soft actuator, the pressure is controlled by a solenoid valve that can, in particular, adjust the duty cycle and operating frequency through a pulse-width modulation (PWM) signal. Figure 4 The overall control diagram of the wearable device is shown. The planner considers the desired movement trajectory to generate a target pressure, which is further evaluated through the proprietary frequency and duty cycle of the valve controller. The generated command is then passed to the pulse-width modulation generator module to generate the corresponding pulse-width modulation signal. The two pulse-width modulation signals are amplified by two power amplifiers and sent to the valve. A pressure feedback loop is thus established to monitor the actual pressure for achieving a more precise trajectory.

[0064] To investigate the impact of the proposed exoskeleton wearable device on mandibular movement, a robotic prototype has been developed and tested on a single robotic joint and a skull model. The conclusions and discussions will be presented in detail.

[0065] Soft Robotic Joint

[0066] The proposed soft robotic joint consists of three parts: a base, an end effector, and two bellows-shaped elliptical soft actuators, as Figure 6 shown. Both the base and the end effector can be made of polylactic acid (PLA) material using a consumer-grade 3D printer. The soft actuators are made by blow molding and are selected according to the parameters shown in Table 1.

[0067] Pneumatic Control System

[0068] The dedicated experimental platform consists of Figure 5The pneumatic control system shown. The pneumatic pressure source and the hydraulic system include two pumps and two pressure tanks. The expansion and contraction of the soft actuator are controlled by two high-frequency solenoid valves connected to the pressure source and the hydraulic tank respectively. The entire system is controlled by a single-chip microcomputer (STM) board, while the analog-to-digital conversion (AD) and drive boards are used for sensors and valves. Pressure sensors are connected to the pressure source and the hydraulic tank to maintain the high and low levels of pressure. In addition, each soft actuator is monitored by a pressure sensor to achieve feedback control of pressure. Therefore, the pneumatic control system can generate a stable and reliable pressure output to the actuator part of the proposed device.

[0069] Supracranial experimental platform

[0070] In addition to the temporomandibular joint structure, normal jaw opening can also be actuated by a series of human muscles including the suprahyoid muscles, pterygoid muscles, masseter muscles, digastric muscles, etc. In this test case, the dysfunction of the muscle group is not considered, which means it is assumed that the patient has the muscle strength to move the jaw, however, joint locking causes pain, or the muscles do not exert force in the correct way. The wearable device helps the patient achieve correct jaw movement. Therefore, the goal of this work is to focus on helping the temporomandibular joint rather than forcing it to open. So, the complex muscle group for jaw movement is achieved by Figure 6 the simple cylinder shown. The cylinder flexibly connected to the lower jaw reproduces the movement trajectory of the slightly curved lower dentition. The proposed soft joint and cylinder actuate the lower jaw simultaneously to perform the opening and closing of a conventional oral cavity that simulates a real biological process.

[0071] Generally, in one embodiment, the weight of the wearable part of the fabricated exoskeleton soft wearable device is 340 grams or less than 340 grams, and it is connected to the pneumatic control platform through two air pipes.

[0072] Lateral compliance test

[0073] To verify the compliance retention ability of the soft robotic joint, a set of tests were conducted on the workbench unit. Force was applied in the Figure 7 direction shown, and the vertical displacement was recorded. Actuation was tested under three sets of pressures, including 0 kPa (kilopascals), 20 kPa, and 40 kPa. From the results, to achieve the same displacement, different loads do not need to be applied, which means that during actuation, compliance in the vertical plane can be significantly maintained.

[0074] Soft robotic joint test

[0075] To verify the simulation performance of the proposed soft robotic joint, a desktop test unit with a soft actuator having two ellipses was actuated by different pneumatic pressure control commands. Three sets of repeated experiments were conducted, including actuating only the upper actuator with a linear pressure change, actuating only the lower actuator, and actuating both actuators. The movement of two markers was tracked by a camera, and computer vision technology was used to obtain the actual trajectory. The test results are shown in Figure 8 、 Figure 9 and Figure 10 , indicating a very good agreement with the calculated trajectory, with a maximum deviation not exceeding 1 millimeter (mm). The analysis model gives a satisfactory simulation of the displacement in this plane. Therefore, to inversely solve the displacement function with respect to pressure, pressure commands were then generated from the desired displacement. Such commands were applied through a pneumatic control platform to simulate the movement according to the desired trajectory.

[0076] In addition, computer vision was used to calculate kinematic characteristics. Velocity, acceleration, angular velocity, and angular acceleration were presented. The actuation response was fast, and the movement performance could be monitored and coordinated with the control system, and the device had the ability to allow the patient to adjust the training process individually.

[0077] Using the verified soft robotic joint, the simulation of the desired trajectory was tested. The movement trajectory of the end effector had been planned according to the real human condylar movement. Using the planned trajectory, the pressure commands were inversely solved through the relationship function. Then, the actual trajectory was collected and compared with the planned trajectory, as shown in Figure 11 . Under the control of the pneumatic control platform, the monitored actual pressure well followed the pressure commands, and the tendency of the movement was very consistent with the planned trajectory. However, due to the control accuracy of the valve used, the movement of the end effector oscillated slightly.

[0078] Using the verification of the soft robotic joint, it was possible to perform movements through the proposed wearable device in a real situation.

[0079] Supracranial test

[0080] To further explore the effect of the proposed wearable device on mouth opening, a supracranial test was conducted. The head ring was mounted to the skull by a soft strap and the end effector of the device was mounted to the mandible by a soft strap. The skull was assumed to be fixed and mounted to a bracket. The mandible was connected to a cylinder and the main movement of opening was actuated by this cylinder. Two opening trajectories were collected and analyzed: 1) without actuating the device; 2) actuating the device. In Figure 12Two trajectories are compared and shown. As shown by the blue triangles and red dots in the figure, it can be clearly observed that applying the proposed device pushes the model condyle out of the gliding movement of the temporomandibular joint structure, which is in line with the physiology of the human body. This gliding exoskeleton support can train patients to open their mouths correctly without causing other injuries to the temporomandibular joint.

[0081] The experimental results and observations are crucial for the development of rehabilitation devices for temporomandibular joint disorders. Compared with existing diagnosis and treatment methods, the design of the proposed exoskeleton soft device has brought three main contributions: 1) significantly simulating the real human jaw movement trajectory, considering the comfort and safety of patients and reducing the total weight of the wearable device; 2) retaining the compliance of the system in other directions during the actuation process of the jaw in the gliding plane, reducing further injuries caused by individual differences during training; 3) conforming to the characteristics of the temporomandibular joint, enabling customizable trajectory planning through pneumatic control, paving the way for further treatment of temporomandibular joint disorders. In addition, it has been confirmed on the skull model that the proposed wearable device can effectively push the condyle of the mandible out of the temporomandibular joint structure.

[0082] The present invention solves the challenges faced by exoskeleton wearable devices for the treatment of temporomandibular joint disorders by providing a soft way to generate temporomandibular joint movement. Exploring the dual-actuator soft robotic joint shows its excellent performance in trajectory simulation using pneumatic control. An exoskeleton soft wearable device was developed using blow molding and 3D printing technologies to achieve the guidance of mandibular movement. Experiments and computer vision acquisitions were carried out on two proposed soft robotic joints and a skull model, revealing the basic mechanism and significant characteristics of temporomandibular joint movement. Compared with existing training methods, the proposed soft exoskeleton wearable device is ultra-lightweight, comfortable and safe for patients, and its implementation is more in line with human physiology.

[0083] The present invention also provides inspiration for the design of rehabilitation devices, providing variable solutions for patients using a system adapted to the soft approach. In addition, the convenient trajectory planning that adapts to individual differences provided by pneumatic control can be customized for the physiological structures of different patients. This amazing customization ability brings practicality and safety to the rehabilitation applications of complex diseases.

[0084] Unless otherwise specified in the examples and in the specification and claims, all parts and percentages are by weight, all temperatures are in degrees Celsius, and the pressure is atmospheric pressure or approximately atmospheric pressure.

[0085] For a given range of figures or numbers for a feature, the figures or parameters of one range can be combined with the figures or parameters of another range for the same feature to produce a numerical range.

[0086] Except in the operating examples, or where otherwise indicated, all numbers, values and / or representations of amounts of ingredients, reaction conditions, etc., used in the specification and claims shall be understood to be modified in all instances by the term "about".

[0087] Since the present invention is described with reference to certain embodiments, it is to be understood that various modifications will be apparent to those skilled in the art upon reading the specification. It is therefore to be understood that the invention disclosed herein is intended to cover such modifications as fall within the scope of the appended claims.

Claims

1. An exoskeleton wearable device for pushing the condyle away from the temporal joint structure of the skull, comprising: Two bellows-shaped soft actuators each with an oval cross-section, which are angularly mounted and driven using pneumatic control; An upper component configured to be mounted to the patient's forehead and serving as a base for the two bellows-shaped soft actuators; A lower component configured to be mounted on the patient's mandible and being substantially stationary relative to the mandible but movable relative to the upper component in a horizontal plane and a vertical plane, wherein the lower component includes an end effector, and the two bellows-shaped soft actuators are angularly connected to a common end effector to apply a force to the mandible upon actuation; And A pneumatic control system configured to provide a pressure output to the soft actuators based on a planned motion trajectory.

2. The exoskeleton wearable device according to claim 1, wherein the two bellows-shaped actuators are pneumatic actuators.

3. The exoskeleton wearable device according to claim 1, provided that the two bellows-shaped actuators do not have a circular cross-section.

4. The exoskeleton wearable device according to claim 1, wherein the upper component is ring-shaped and arranged to be substantially stationary during mandibular movement.

5. The exoskeleton wearable device according to claim 1, wherein the pneumatic control system includes a pressure sensor, a solenoid valve, and a drive board.

6. The exoskeleton wearable device according to claim 1, having a weight of 340 grams or less than 340 grams.

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