A Flexible Rehabilitation Glove Based on a Hybrid Driver

Abstract

The present invention discloses a flexible rehabilitation glove based on a hybrid driver, which includes five hybrid drivers and a control box for the drivers; the hybrid driver includes a driver end mount, a flexible driver, a TPFE water pipe, a front mount of the flexible driver, a flexible driver air pipe, a second air pipe connection seat, an SMA spring driver, a first air pipe connection seat, and a cooling water pipe. Inside the control box, there are an air pump, a filter, a water pump and a water tank, a proportional valve, and a control circuit board. The filter is respectively connected to the air pump and the electro-hydraulic proportional valve. The outside of the control box includes a driver control box body, a control box lid, a main switch, buttons, and a voltage display. This flexible rehabilitation glove combines the characteristics of large output torque of the flexible driver and high force-mass ratio of the SMA, solves the problem that the traditional flexible driver can only move unidirectionally, drives the patient's fingers to move bidirectionally, and provides sufficient working torque and working space in both directions for the patient.

Description

Technical Field

[0001] The present invention belongs to the field of upper limb exoskeleton rehabilitation robots, and particularly relates to a flexible exoskeleton glove system for hand rehabilitation training. Background Art

[0002] Stroke is a common disease caused by cerebrovascular diseases. The number of patients with hand function disorders caused by stroke is increasing gradually. Hand function is an important factor leading to the quality of life of patients. Complete hand function can help patients complete various complex living needs and daily work, and can also be used as a tool for emotional expression.

[0003] Traditional rehabilitation robots use rigid link structures to help patients perform actions such as relaxation and flexion, and use the rigid link structures to drive the patient's fingers to move along a preset trajectory. There are problems such as difficult wearing and alignment of the rotation center in the rigid structure.

[0004] Flexible rehabilitation robots can solve the above problems. Due to the flexibility of the flexible material itself, extensive research has been carried out on robots based on flexible actuators. Among them:

[0005] Patent CN 107242958 B proposes a rehabilitation training system for an exoskeleton glove based on a flexible actuator, which can help patients perform bending rehabilitation training actions;

[0006] Patent CN 111685964 A proposes a hand rehabilitation device based on shape memory alloy. The device uses ropes and shape memory alloy to drive the patient to perform contraction and extension of the hand, and perform rehabilitation training on the patient's fingers.

[0007] However, there are still some problems in the above patents:

[0008] 1. Lack of the rehabilitation device in the extension and flexion directions;

[0009] 2. Insufficient output force and working space of the rehabilitation device;

[0010] Therefore, further improvement is needed. Summary of the Invention

[0011] To solve the above problems, the present invention discloses a flexible rehabilitation glove based on a hybrid actuator, which can provide output force and working space for the patient's fingers in two directions of flexion and extension, and solve the defect that the traditional flexible actuator can only move in one direction.

[0012] To achieve the above object, the technical solution of the present invention is as follows:

[0013] A flexible rehabilitation glove based on a hybrid actuator, comprising five hybrid actuators and a control box for the actuators;

[0014] The hybrid drive includes a drive end mount, a flexible drive, a TPFE water pipe, a flexible drive, a flexible drive air pipe, an air pipe connection seat II, an SMA spring drive, an air pipe connection seat I, a cooling water pipe,

[0015] The hybrid drive is connected to the glove by an elastic band, and the extension and flexion of the hybrid drive drive the patient's fingers to move.

[0016] The flexible drive is made of silica gel and has a multi-chamber structure. It consists of two parts, the upper and the lower, as Figure 7 shown. Among them, the upper layer is wavy, with a hollow cavity in the middle of each wave crest, and the lower layer is rectangular, with a groove for conducting gas in the middle. The flexible drive is set with a wavy cavity that is thin on the contact surface and thick on the non-contact surface. During the inflation process of the flexible drive, the contact surface deforms greatly, and the cavities squeeze each other, forming the bending of the drive.

[0017] Both ends of the flexible drive are respectively connected to the flexible drive front mount and the flexible drive end mount. The inside of the drive is a hollow structure, and the flexion and extension of the flexible drive are realized through inflation and deflation. The flexible drive is connected to the air pump through the flexible drive air pipe, and the internal air pressure is controlled by the control program in the control circuit board through an electro-pneumatic proportional valve.

[0018] The SMA spring drive is sleeved on the cooling water pipe. This water pipe serves as a guide for the rope movement and reduces the temperature of the water pipe through the internal water flow. Through sufficient contact between the water pipe and the SMA spring drive, it cools the spring drive. The SMA spring drive is connected to the drive end mount through a rope that passes through two holes on the flexible drive front mount and two holes on the flexible drive. Through the tension of the spring, it can help the flexible drive provide a reverse stretching force.

[0019] Water pipes made of Teflon (TPFE) material are respectively placed in the middle of the two holes on the flexible drive. These water pipes can reduce the friction caused by the relative movement between the rope and the flexible drive and increase the efficiency of the system.

[0020] The cooling water pipe is respectively installed with an air pipe connection seat I and an air pipe connection seat II at both ends of the flexible drive to fix the position of the water pipe through the two connection seats. Among them, the air pipe connection seat I fixes the end position of the SMA spring drive, and the air pipe connection seat II limits the movement range of the other end of the SMA spring drive.

[0021] The inside of the control box includes an air pump, a filter, a water pump and a water tank, a proportional valve, and a control circuit board. The outside of the control box includes a drive control box body, a control box lid, a main switch, a button, and a voltage display.

[0022] Among them, the air pump can provide an air pressure of 250 KPa for the system. By increasing the air pressure inside the flexible actuator, the flexible actuator can achieve the degree of freedom of flexion.

[0023] The filter is respectively connected to the air pump and the electro-pneumatic proportional valve. Through the filter, impurities and water vapor in the air can be filtered out, reducing the damage of impurities to the proportional valve.

[0024] The water pump and the water tank mainly provide low-temperature water flow for the cooling water pipe to cool the SMA spring actuator.

[0025] The control box of the actuator and the cover of the control box are connected by the suction force of the magnets at the four corners, and can be conveniently opened and closed.

[0026] The button can set several special gestures through the program. Through the button, the glove can be controlled to drive the patient's fingers to perform special gesture assistance, helping the patient achieve functions in daily life.

[0027] Driving principle:

[0028] The hybrid drive consists of two parts: a flexion actuator and an extension actuator. Among them, the flexion actuator is a flexible actuator, and the extension actuator is an SMA spring actuator.

[0029] The flexible drive has two states: the initial state and the pressurized state. Among them, the initial state is rectangular, and the pressurized state is arc-shaped. By controlling the pressure inside the flexible actuator, the bending angle of the flexible actuator can be changed to achieve the purpose of controlling the flexion and extension of the flexible actuator. Although the flexible actuator is rectangular in the initial state, due to the small internal stress of the flexible actuator, it cannot overcome the finger resistance and return to the extended state. Therefore, we added an extension actuator: the SMA spring actuator.

[0030] The SMA spring actuator is a spring made of shape memory alloy. The shape memory alloy has two states: martensite and austenite, and the state is changed by controlling the temperature of the SMA. When the temperature of the shape memory alloy is low, the state of the SMA spring is martensite. At this time, the elastic coefficient of the SMA spring is low, and the elastic force of the SMA spring is low; when the temperature of the shape memory alloy is high, the state of the SMA spring is austenite. At this time, the elastic coefficient of the SMA spring is high, and the spring has a high elastic force.

[0031] The specific control block diagram of the driving principle is as Figure 6 shown:

[0032] Among them, during the movement in the buckling direction, the pressure inside the flexible actuator increases, driving the rope. The movement of the rope pulls the SMA spring actuator. Since the cooling air pipe cools the SMA spring actuator without heating, it can ensure that the SMA spring is in the martensite state during the stretching movement. The martensite SMA material has a relatively small rigidity and a relatively small damping effect on the movement of the flexible actuator.

[0033] In addition, during the movement in the stretching direction, by passing an electric current through the SMA spring to increase its temperature, the stiffness of the SMA spring increases. The SMA spring pulls the rope, driving the reverse movement of the mounting seat at the end of the flexible actuator. At the same time, the air pressure inside the flexible actuator decreases, bringing the flexible actuator back to its initial state, and the damping force on the movement of the SMA spring is relatively small.

[0034] In order to better assist patients in their daily activities, a modeling analysis is carried out on the hybrid actuator.

[0035] The modeling of the hybrid actuator mainly consists of a flexible actuator and an SMA spring actuator.

[0036] 1. Modeling of the shape memory alloy spring actuator

[0037] Hooke's law of elasticity states that:

[0038] F SMA = kX

[0039] where k is the elastic coefficient of the spring and X is the deformation of the spring.

[0040] Under the condition of ensuring the accuracy of the actuator, the SMA shape memory alloy spring is simplified, and the elastic coefficient of the SMA shape memory alloy is obtained as

[0041]

[0042] where k A is the elastic coefficient of the shape memory alloy spring in the austenite state, and the expression is k M is the elastic coefficient of the shape memory alloy spring in the martensite state, and the expression is T is the temperature of the SMA spring, the austenite phase transformation start temperature A s , the austenite phase transformation end temperature A f . Among them, C1 and C2 are constants, and the expressions are

[0043]

[0044] In the formula, k s is the stress correction elastic coefficient formula, and the expression is

[0045]

[0046] Where: C is the spring index, D is the diameter of the spring, d is the wire diameter of the spring, and N is the number of spring coils.

[0047] 2. Modeling of the flexible actuator

[0048] During the inflation process, the pressure in each cavity of the actuator is the same. Let the internal pressure of the airbag be P. Conduct a force analysis on a single surface of the actuator. Using σ to represent the internal stress in the base cross-section, from the force balance equation, it can be known that

[0049] σt 2 = P(h + t) 2

[0050] Where, h is the internal height of the cavity, and t is the thickness of the cavity base.

[0051] Based on the Yeoh model, the energy equation in the typical two-parameter form is

[0052]

[0053] Where, C3 and C4 are coefficients, C3 = 0.11 and C4 = 0.02, I is the invariant of the deformation tensor, and λ is the principal stretch ratio.

[0054] Express the internal stress as The relationship between the internal stress σ and the principal stretch ratio λ can be obtained as

[0055]

[0056] Expand the above formula and ignore the small quantities of the second order and above orders, and the following can be obtained

[0057] σ = 8C3(λ3 - 1)

[0058] The principal stretch ratio of a single airbag of the flexible actuator is θ represents the bending angle generated by a single airbag under a certain internal air pressure, that is φ is the bending angle of the flexible actuator, and N is the number of airbags.

[0059] 3. Modeling of the hybrid actuator

[0060] According to the force balance relationship, the output force model of the hybrid actuator is obtained as:

[0061] σ - F SMA - F0 - F Muscle = 0

[0062] Where: F SMA is the output force of the shape memory alloy, F0 is the initial force of the hybrid actuator, F MuscleFor the auxiliary force of the hybrid actuator and the human finger.

[0063] Substituting the models of the SMA spring actuator and the flexible actuator into the above formula, the auxiliary force of the hybrid actuator on the patient's finger can be obtained:

[0064]

[0065] In the formula, X is the elongation of the spring, and the expression is X = L*(λ - 1)*2, P i is the pressure inside the flexible actuator at the i-th moment, and L is the length of the actuator.

[0066] The effective effects of this invention patent are:

[0067] ) This hybrid actuator combines the characteristics of large output torque of the flexible actuator and high force-to-mass ratio of SMA, solves the problem that the traditional flexible actuator can only move unidirectionally, drives the patient's finger to move bidirectionally, and provides sufficient working torque and working space in both directions for the patient.

[0068] 2) This hybrid actuator cools down the SMA spring actuator by water cooling, which can improve the cooling speed of the actuator and the response speed of the actuator. [[ID=])

[0069] 3) A model of the hybrid actuator is established. Based on the stability of the shape memory alloy spring actuator and the internal pressure of the flexible actuator of the hybrid actuator, the bending angle and auxiliary force of the actuator are calculated according to the model. Description of the Drawings

[0070] Figure 1 is the wearing schematic diagram of the hybrid actuator when it extends in the present invention;

[0071] Figure 2 is the wearing schematic diagram of the hybrid actuator when it buckles in the present invention;

[0072] Figure 3 is the schematic diagram of the control box structure in the present invention;

[0073] Figure 4 is Figure 3 the internal structure schematic diagram of the control box in

[0074] Figure 5 is the wearing schematic diagram of the flexible actuator in the present invention;

[0075] Figure 6 is the control block diagram of the flexible actuator in the present invention;

[0076] Figure 7 is the cross-sectional schematic diagram of the flexible actuator in the present invention.

[0077] Figure 8It is the buckling schematic diagram of the flexible actuator described in the present invention.

[0078] Figure 9 It is the stretching schematic diagram of the flexible actuator described in the present invention.

[0079] In the figure: 1 - Drive end mount, 2 - Flexible actuator, 3 - TPFE water pipe, 4 - Front section mount of flexible actuator, 5 - Flexible actuator air pipe, 6 - Second air pipe connection seat, 7 - SMA spring actuator, 8 - First air pipe connection seat, 9 - Cooling water pipe, 10 - Drive control box, 11 - Control box lid, 12 - Main switch, 13 - Button, 14 - Voltage display, 15 - Air pump, 16 - Filter, 17 - Water pump and water tank, 18 - Proportional valve, 19 - Control circuit board. Specific embodiments

[0080] The following further clarifies the present invention in conjunction with the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are only used to illustrate the present invention and not to limit the scope of the present invention.

[0081] As shown in the figure, a flexible rehabilitation glove based on a hybrid actuator described in the present invention includes five hybrid actuators and a control box for the actuators;

[0082] The hybrid actuator includes a drive end mount 1, a flexible actuator 2, a TPFE water pipe 3, a front section mount 4 of the flexible actuator, a flexible actuator air pipe 5, a second air pipe connection seat 6, an SMA (shape memory alloy) spring actuator 7, a first air pipe connection seat 8, and a cooling water pipe 9.

[0083] The hybrid actuator is connected to the glove through an elastic band, and the stretching and buckling of the hybrid actuator drive the patient's fingers to move.

[0084] The flexible actuator 2 is made of silica gel. By increasing the pressure inside the flexible actuator, the volume of the flexible actuator increases. At the same time, the size of the flexible actuator is designed such that the inner wall of the actuator air chamber in the axial direction is thin, and the inner wall of the actuator air chamber in the radial direction is thick. In this way, increasing the air pressure will cause a large axial deformation of the flexible actuator, and the radial deformation is almost zero.

[0085] Both ends of the flexible actuator 2 are respectively connected to the front section mount 4 of the flexible actuator and the drive end mount 1. The inside of the actuator is a hollow structure, and the buckling and stretching actions of the flexible actuator are realized through inflation and deflation. The flexible actuator 2 is connected to the air pump 15 through the flexible actuator air pipe 5, and the air pressure inside is controlled by the control program in the control circuit board 19 through the electro-hydraulic proportional valve 18.

[0086] The SMA spring driver is sleeved on the cooling water pipe. This water pipe serves as a guide for the movement of the rope and reduces the temperature of the water pipe through the internal water flow. Through sufficient contact between the water pipe and the SMA spring driver 7, it cools the spring driver. The SMA spring driver 7 is connected to the driver end mount 1 through a rope, passing through two holes on the front mount 4 of the flexible driver and two holes on the flexible driver 2. Through the tension of the spring, it can help the flexible driver 2 provide a reverse stretching force.

[0087] Teflon (TPFE) pipes are respectively placed between the two holes on the flexible driver 2. These pipes can reduce the friction caused by the relative movement between the rope and the flexible driver, increasing the efficiency of the system.

[0088] Air pipe connectors one 8 and air pipe connectors two 6 are respectively installed at both ends of the cooling water pipe 9 and the flexible driver 2 to fix the position of the water pipe through the two connectors. Among them, the air pipe connector one 8 fixes the end position of the SMA spring driver 7, and the air pipe connector two 6 limits the movement range of the other end of the SMA spring driver 7.

[0089] Inside the control box 10, there are an air pump 15, a filter 16, a water pump and a water tank 17, a proportional valve 18, and a control circuit board 19. Outside the control box, there are a driver control box body, a control box lid 11, a main switch 12, a button 13, and a voltage display 14.

[0090] Among them, the air pump 15 can provide an air pressure of 250 KPa for the system. By increasing the air pressure inside the flexible driver, the flexible driver can achieve the degree of freedom of buckling.

[0091] The filter 16 is respectively connected to the air pump 15 and the electro-pneumatic proportional valve 18. Through the filter, impurities and water vapor in the air can be filtered out, reducing the damage of impurities to the proportional valve.

[0092] The water pump and water tank 17 mainly provide low-temperature water flow for the cooling water pipe to cool the SMA spring driver.

[0093] The control box 10 of the driver and the control box lid 11 are connected by the suction force of the magnets at the four corners, which can be conveniently opened and closed.

[0094] The button 13 can set several special gestures through a program. Through the button, it can control the glove to drive the patient's fingers to perform special gesture assistance, helping the patient achieve functions in daily life.

[0095] Among them, during the movement in the buckling direction, the pressure inside the flexible actuator increases, driving the rope. The movement of the rope pulls the SMA spring actuator. Since the cooling air pipe cools the SMA spring actuator without heating, it can ensure that the SMA spring is in the martensite state during the stretching movement. The martensite SMA material has a relatively small rigidity and a relatively small damping effect on the movement of the flexible actuator.

[0096] In addition, during the movement in the stretching direction, by passing an electric current through the SMA spring to heat it up, the stiffness of the SMA spring increases. The SMA spring pulls the rope, driving the reverse movement of the mounting seat at the end of the flexible actuator. At the same time, the air pressure inside the flexible actuator decreases, making the flexible actuator return to its initial state, and the damping force on the movement of the SMA spring is relatively small.

[0097] In order to better assist patients in their daily activities, a modeling analysis of the hybrid actuator is carried out.

[0098] The modeling of the hybrid actuator mainly consists of a flexible actuator and an SMA spring actuator.

[0099] 1. Modeling of the shape memory alloy spring actuator

[0100] Hooke's law of elasticity states that:

[0101] F SMA = kX

[0102] where k is the elastic coefficient of the spring and X is the deformation of the spring.

[0103] Under the condition of ensuring the accuracy of the actuator, the SMA shape memory alloy spring is simplified, and the elastic coefficient of the SMA shape memory alloy is obtained as

[0104]

[0105] where k A is the elastic coefficient of the shape memory alloy spring in the austenite state, and the expression is k M is the elastic coefficient of the shape memory alloy spring in the martensite state, and the expression is T is the temperature of the SMA spring, the austenite phase transformation start temperature A s , the austenite phase transformation end temperature A f . Among them, C1 and C2 are constants, and the expressions are

[0106]

[0107] In the formula, k s is the stress correction elastic coefficient formula, and the expression is

[0108]

[0109] Where: C is the spring index, D is the diameter of the spring, d is the wire diameter of the spring, and N is the number of spring coils.

[0110] 2. Modeling of Flexible Actuator

[0111] During the inflation process, the pressure in each cavity of the actuator is the same. Let the internal pressure of the airbag be P. Conduct a force analysis on a single surface of the actuator. Using σ to represent the internal stress in the base cross-section, it can be known from the force balance equation that

[0112] σt 2 = P(h + t) 2

[0113] Where h is the internal height of the cavity and t is the thickness of the cavity base.

[0114] Based on the Yeoh model, the energy equation in the typical two-parameter form is

[0115]

[0116] Where C3 and C4 are coefficients, C3 = 0.11 and C4 = 0.02, I is the invariant of the deformation tensor, and λ is the principal stretch ratio.

[0117] Express the internal stress as The relationship between the internal stress σ and the principal stretch ratio λ can be obtained as

[0118]

[0119] Expand the above formula and ignore the small quantities of the second order and higher orders, and the following can be obtained

[0120] σ = 8C3(λ3 - 1)

[0121] The principal stretch ratio of a single airbag of the flexible actuator is θ represents the bending angle generated by a single airbag under a certain internal air pressure, that is φ is the bending angle of the flexible actuator, and N is the number of airbags.

[0122] 3. Modeling of Hybrid Actuator

[0123] According to the force balance relationship, the output force model of the hybrid actuator is obtained as:

[0124] σ - F SMA - F0 - F Muscle = 0

[0125] Where: F SMA is the output force of the shape memory alloy, F0 is the initial force of the hybrid actuator, F MuscleFor the auxiliary force of the hybrid driver and the human finger.

[0126] Substituting the models of the SMA spring driver and the flexible driver into the above formula, the auxiliary force of the hybrid driver on the patient's finger can be obtained:

[0127]

[0128] In the formula, X is the elongation of the spring, and the expression is X = L*(λ - 1)*2, P i is the pressure inside the flexible driver at the i-th moment, and L is the length of the driver.

[0129] It should be noted that the above content only illustrates the technical idea of the present invention and cannot be used to limit the protection scope of the present invention. For those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements all fall within the protection scope of the claims of the present invention.

Claims

1. A flexible rehabilitation glove based on a hybrid driver, characterized in that: It includes five hybrid drivers and a control box for the drivers; The hybrid driver includes a driver end mount, a flexible driver, a TPFE water pipe, a front mount for the flexible driver, a flexible driver air pipe, a second air pipe connection seat, an SMA spring driver, a first air pipe connection seat, and a cooling water pipe. The flexible driver is made of silicone and is a multi-cavity structure, consisting of an upper and a lower part. Among them, the upper layer is in a wave shape, with a hollow cavity in the middle of each wave crest, and the lower layer is rectangular, with a groove for conducting gas left in the middle; the cavity of the flexible driver set in a wave shape is thin on the contact surface and thick on the non-contact surface. During the inflation process of the flexible driver, the contact surface deforms greatly, and the cavities squeeze each other, forming the bending of the driver. Both ends of the flexible driver are respectively connected to the front mount for the flexible driver and the driver end mount. The flexible driver is connected to an air pump through the flexible driver air pipe, and the internal air pressure is controlled by an electrical proportional valve through a control program in the control circuit board. The SMA spring driver is sleeved on the cooling water pipe. This water pipe serves as a guide for the movement of the rope and reduces the temperature of the water pipe through the internal water flow. By making full contact between the water pipe and the SMA spring driver, it cools the spring driver; the SMA spring driver is connected to the driver end mount through a rope passing through two holes on the front mount for the flexible driver and two holes on the flexible driver, and with the tension of the spring, it helps the flexible driver provide a reverse stretching force. The cooling water pipe is respectively installed with the first air pipe connection seat and the second air pipe connection seat at both ends of the flexible driver to fix the position of the water pipe through the two connection seats; among them, the first air pipe connection seat fixes the end position of the SMA spring driver, and the second air pipe connection seat limits the movement range of the other end of the SMA spring driver. Inside the control box, there are an air pump, a filter, a water pump and a water tank, a proportional valve, and a control circuit board. The filter is respectively connected to the air pump and the electrical proportional valve. The outside of the control box includes a driver control box body, a control box lid, a main switch, buttons, and a voltage display.

2. The flexible rehabilitation glove based on a hybrid driver according to claim 1, wherein: The air pressure provided by the air pump is 250 KPa.

3. The flexible rehabilitation glove based on a hybrid driver according to claim 1, wherein: The control box of the driver and the lid of the control box are connected by the suction force of magnets at the four corners.

4. The flexible rehabilitation glove based on a hybrid driver according to claim 1, wherein: Two TPFE water pipes are respectively placed in the middle of the two holes on the flexible driver.

5. A flexible rehabilitation glove based on a hybrid driver according to claim 1, characterized in that: Its movement principle is: The hybrid driver is connected to the glove through an elastic band. By inflating and deflating, it drives the extension and flexion of the hybrid driver, thereby driving the patient's fingers to move; The hybrid drive consists of two parts: a flexion driver and an extension driver. Among them, the flexion driver is a flexible driver, and the extension driver is an SMA spring driver; The flexible drive has two states: an initial state and a pressurized state. Among them, the initial state is rectangular, and the pressurized state is arc-shaped; by controlling the pressure inside the flexible driver, the bending angle of the flexible driver is changed to achieve the purpose of controlling the flexion and extension of the flexible driver. The SMA spring actuator is a spring made of shape memory alloy. The shape memory alloy has two states, martensite and austenite, and the state transition is controlled by the temperature of the SMA. When the temperature of the shape memory alloy is low, the state of the SMA spring is martensite. At this time, the elastic coefficient of the SMA spring is low and the elastic force of the SMA spring is low. When the temperature of the shape memory alloy is high, the state of the SMA spring is austenite. At this time, the elastic coefficient of the SMA spring is high and the spring has a high elastic force. Among them, the movement in the buckling direction is caused by the increase in pressure inside the flexible actuator, driving the rope. The movement of the rope pulls the SMA spring actuator. Since the cooling air pipe cools the SMA spring actuator without heating up, this ensures that during the stretching movement, the SMA spring is in the martensite state. The SMA material in the martensite state has low rigidity and small damping to the movement of the flexible actuator. In addition, during the movement in the stretching direction, by passing an electric current through the SMA spring to increase its temperature, the stiffness of the SMA spring increases. The SMA spring pulls the rope, driving the reverse movement of the mounting seat at the end of the flexible actuator. At the same time, the air pressure inside the flexible actuator decreases, making the flexible actuator return to its initial state and having a small damping force on the movement of the SMA spring.

6. The flexible rehabilitation glove based on a hybrid driver according to claim 1, characterized in that: In order to better assist patients in their daily activities, a modeling analysis is carried out on the hybrid actuator: The modeling of the hybrid actuator mainly consists of a flexible actuator and an SMA spring actuator:

1. Modeling of the shape memory alloy spring actuator Hooke's law of elasticity states that: F SMA = kX Among them, k is the elastic coefficient of the spring, and X is the deformation of the spring; Under the condition of ensuring the accuracy of the actuator, the SMA shape memory alloy spring is simplified, and the elastic coefficient of the SMA shape memory alloy is obtained as where k A is the elastic coefficient of the shape memory alloy spring in the austenite state, and the expression is k M is the elastic coefficient of the shape memory alloy spring in the martensite state, and the expression is T is the temperature of the SMA spring, the austenite phase transformation start temperature A s , the austenite phase transformation end temperature A f , where C1 and C2 are constants, and the expression is where k s is the stress correction elastic coefficient formula, and the expression is Where: C is the spring index, D is the diameter of the spring, d is the wire diameter of the spring, and N is the number of spring coils; 2. Modeling of the flexible actuator During the inflation process, the pressure in each cavity of the actuator is the same. Let the internal pressure of the airbag be P. Analyze the force on a single surface of the actuator. Using σ to represent the internal stress of the base cross-section, from the force balance equation, we know σt 2 = P(h + t) 2 In the formula, h is the internal height of the cavity, and t is the thickness of the cavity base; Based on the Yeoh model, the typical two-parameter form of the energy equation is In the formula, C3 and C4 are coefficients, C3 = 0.11 and C4 = 0.02, I is the invariant of the deformation tensor, and λ is the principal elongation ratio; Express the internal stress as The relationship between the internal stress σ and the principal elongation ratio λ is obtained as Expand the above formula and ignore the small quantities of the second order and above orders, we get σ = 8C3(λ - 1) The main elongation ratio of a single airbag of the flexible actuator is θ represents the bending angle generated by a single airbag under internal air pressure, that is φ is the bending angle of the flexible actuator, and N is the number of airbags; 3. Modeling of the hybrid actuator According to the force balance relationship, the output force model of the hybrid actuator is obtained as: σ-F SMA -F0-F Muscle = 0 Where: F SMA is the output force of the shape memory alloy, F0 is the initial force of the hybrid actuator, and F Muscle is the auxiliary force of the hybrid actuator and the human finger; Substitute the models of the SMA spring actuator and the flexible actuator into the above formula to obtain the auxiliary force of the hybrid actuator on the patient's finger: Wherein, X is the elongation of the spring, and the expression is X = L*(λ - 1)*2, P i is the pressure inside the flexible actuator at the i-th moment, and L is the length of the actuator.

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