Control system and control method of pneumatic soft hand rehabilitation robot

Abstract

The invention belongs to the technical field of rehabilitation robots, and particularly relates to a control system and a control method of a pneumatic soft hand rehabilitation robot. The system is used for controlling the pneumatic soft hand robot to move. The hand robot comprises a main bending module, a middle air pipe connecting layer and a reverse bending module which are sequentially connected from top to bottom, and a bidirectional bending structure with an upper cavity and a lower cavity is arranged in the hand robot. And a control circuit of the system comprises a controller and electrical elements which are respectively connected with the controller and are used for controlling the main bending gas circuit and the reverse bending gas circuit. The controller is internally provided with program units, the program units are matched with one another to output instructions to control corresponding electrical elements so as to control the working states of the main bending gas circuit and the reverse bending gas circuit, and the air pump is combined to inflate the main bending module or the reverse bending module through the middle gas pipe connecting layer. And the bending and stretching actions of the pneumatic soft hand robot are realized. Different finger joints are ventilated so as to assist the finger with the injured hand in stretching and bending, various rehabilitation postures and auxiliary grabbing tasks are completed, and the purpose of helping a patient with the injured hand to recover better is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of rehabilitation robots, and in particular relates to a control system and a control method of a pneumatic soft hand rehabilitation robot. Background Art

[0002] In recent years, soft robots have become a research hotspot in the field of robotics. They are a new type of continuous bionic robots made of flexible materials.

[0003] Robot-assisted repetitive task training can effectively help the recovery of hand function. In order to overcome the limitations of traditional robots, soft hand rehabilitation robots use soft actuators to achieve finger rehabilitation and assisted movement. Among them, pneumatically driven soft rehabilitation robots are light, flexible, and safe, and are suitable for hand assistance and rehabilitation. However, most of the current pneumatic soft hand rehabilitation robots can only achieve unidirectional bending of fingers. Therefore, designing a bidirectionally bending pneumatic soft hand rehabilitation robot can better meet the rehabilitation training needs of patients with hand injuries.

[0004] In addition, researchers have studied and designed soft robotic actuators that mimic human finger movements, including bidirectional bending actuators. Many of these soft robotic hands consist of fluid-driven soft actuators, which use fluids in hollow soft structures for pneumatic or hydraulic actuation. Although soft actuators have received great attention, their fluid-driven systems have received little attention. The pneumatic drive platform of soft hand robots can use compressed air as power, mainly using air pumps as the air source, and various valves to control the flow of air. The most popular pneumatic control architecture is an open source hardware platform for fluid control, which can be obtained from a control board. The control board mainly consists of a diaphragm pump and a solenoid valve. The control algorithm is implemented on an Arduino microcontroller, which can regulate pressure within a single system. Soft hand rehabilitation robot systems are becoming more and more complex, requiring the ability to control complex motion functions of the actuator. Among them, relays and solenoid valves play a key role. The setup with solenoid valves has been introduced in the literature on soft hand rehabilitation robots. Very few hardware and control platforms for controlling bidirectional bending soft actuators have been introduced. Therefore, it is particularly important to design an easily scalable and inexpensive hardware platform that enables a bidirectionally bending pneumatic soft manipulator rehabilitation robot to assist hand injury patients in performing a variety of rehabilitation exercises. Summary of the invention

[0005] In view of the above problems, the purpose of the present invention is to design a hardware platform including gas circuits and circuits, which is mainly composed of gas circuit modules and circuit modules, and includes components such as programmable controllers, relays, solenoid valves, air pumps, overflow valves and sensors. A soft hand rehabilitation robot with bidirectional bending can be controlled. The opening and closing of electrical components in the gas circuit and circuit are controlled by an Arduino microcontroller to control the soft hand rehabilitation robot to assist hand-impaired patients in completing rehabilitation training and auxiliary tasks.

[0006] In order to achieve the above object, the present invention adopts the following technical solution: a control method of a pneumatic soft hand robot, comprising the following steps:

[0007] Step 1, real-time acquisition and recording of feedback signals and control signals of the pneumatic soft hand robot; the control and feedback signal data include air pressure signal data, finger angle signal data, finger pressure signal data, and control circuit signal data; the control circuit signal data include relay signals and solenoid valve opening signals;

[0008] Step 2: Calculate the corresponding air pressure output value at a given target bending angle according to the mathematical model of air pressure-bending angle;

[0009] Step 3: According to the air pressure, angle and finger pressure output values, the relay adjusts the signal to control the pneumatic soft hand robot to perform various bending shapes.

[0010] The mathematical model of the main bending module includes:

[0011] Define the length of the unit air cavity module as a, the expanded length of the module after inflation as b, the height as h, the bending angle as θ, the width of the module as c, and the error caused by environmental factors as E, then the bending angle θ is:

[0012]

[0013] According to Avogadro's hypothesis, the equilibrium equation for gas volume and mass is derived from Clapham's equation:

[0014]

[0015] Where P (Pa) is the pressure, V (m 3 ) is volume, m(g) is mass, μ(g / mol) is molar mass, T(℃) is absolute temperature, and R is a constant;

[0016] When the main bending module cavity is expanded, a single air chamber is regarded as a semi-ellipsoid, and the volume expression of a single inflated air chamber is as follows:

[0017]

[0018] According to equations (1)-(3), the relationship between output air pressure and bending angle is obtained:

[0019]

[0020] The mathematical model of the reverse bending module includes:

[0021] In order to meet the requirements of reverse bending without affecting the finger flexion angle, the middle part is designed as an isosceles trapezoid, and the side is an irregular trapezoid with the same inclination angle; the height of the reverse bending module is h1, the length of the upper base is b1, the length of the lower base is a1, the angle between the lower base and the side of the trapezoid is α1, and the width of the module is c, then:

[0022]

[0023] Among them, t is the hypotenuse of the trapezoid; R is the radius of the fan after expansion; ε is half of the central angle; θ is half of the bending angle;

[0024] When the reverse bending module cavity is expanded, a single chamber is represented as:

[0025] V=2εR 2 c-Rtccosε+(a1+b1)h1c / 2 (6)

[0026] According to Avogadro's hypothesis, the equilibrium equation for gas volume and mass is derived from Clapham's equation:

[0027]

[0028] Where P'(Pa) is the pressure, V(m 3 ) is the volume, m0(g) is the mass, μ0(g / mol) is the molar mass, T0(℃) is the absolute temperature, and R0 is a constant;

[0029] According to equations (5)-(7), the relationship between output air pressure and bending angle is obtained:

[0030]

[0031] A control system for a pneumatic soft hand robot, the system is used to control the movement of the pneumatic soft hand robot;

[0032] The pneumatic soft hand robot comprises: a main bending module, an intermediate air pipe connection layer and a reverse bending module connected in sequence from top to bottom, wherein the main bending module is provided with two or three groups of upper cavity structures protruding upward and independent, the reverse bending module is provided with a lower cavity structure protruding downward, and the intermediate air pipe connection layer is used to connect the main bending module and the reverse bending module, and provide air pressure for the lower cavity structure and each upper cavity structure;

[0033] The control circuit of the system includes: a controller and electrical components connected thereto for controlling a main bending air circuit and a reverse bending air circuit respectively; the working states of the main bending air circuit and the reverse bending air circuit are controlled by the electrical components; the air pump power input end of the main bending air circuit and the reverse bending air circuit is connected to a motor driver, and the common intermediate connecting air circuit end of the main bending air circuit and the reverse bending air circuit is connected to the intermediate air pipe connecting layer of the pneumatic soft hand robot; the controller is equipped with various program units, and the program units cooperate with each other to output instructions to control corresponding electrical components, thereby controlling the working states of the main bending air circuit and the reverse bending air circuit, and combining with the air pump to inflate the main bending module and the reverse bending module through the intermediate air pipe connecting layer to realize the bending and stretching movements of the pneumatic soft hand robot.

[0034] The control circuit also includes at least two air pressure sensors connected to the controller; the air pressure sensor I is arranged in the main air circuit of the inflation pipeline or the main bending air circuit directly connected to the main bending module; the air pressure sensor II is arranged in the main air circuit of the inflation pipeline or the reverse bending air circuit directly connected to the reverse bending module; and is used to collect real-time inflation air pressure signal data.

[0035] The electrical components for controlling the main bending air circuit and the reverse bending air circuit include an air pump, an overflow valve, a relay, a two-position two-way solenoid valve and a two-position three-way solenoid valve, and the relay is connected to the controller; the circuit structures of the main bending circuit and the reverse bending circuit are the same, both including: five branches composed of relays and two-position two-way solenoid valves, respectively controlling the forward bending and reverse bending of the five fingers; the relays are connected to the controller, and the controller outputs signals to each relay so that the two-position two-way solenoid valves in each branch of the main bending circuit and each branch of the reverse bending circuit are powered on; the two-position two-way solenoid valves of the main bending circuit respectively control the two-position three-way solenoid valves, which are connected to the main bending air circuit The main bending module of the pneumatic soft robot is connected; the two-position two-way solenoid valve of the reverse bending circuit is connected to the reverse bending module of the pneumatic soft robot through the reverse bending air circuit; the main bending air circuit and the reverse bending air circuit are both connected to an air pump; the controller outputs a signal to each two-position two-way solenoid valve to adjust the opening of the valve, and outputs a signal to the motor driver to control the operation of the air pump and adjust the flow rate of the air output by the air pump, so as to provide air pressure to the upper cavity structure and each lower cavity structure of the main bending module and the reverse bending module; the input end of the overflow valve is connected to the air outlet of the air pump, and the output end of the overflow valve is connected to the inflation air circuit to release the excess air pressure of the system and keep the air pressure of the system constant.

[0036] Each program unit includes:

[0037] The signal acquisition and recording unit acquires and records the feedback signal and control signal of the pneumatic soft hand robot in real time; the control and feedback signal data include air pressure signal data, finger angle signal data, finger pressure signal data, and control circuit signal data; the control circuit signal data include relay signal and solenoid valve opening signal;

[0038] A model calculation unit calculates the corresponding air pressure output value at a given target bending angle according to a mathematical model of air pressure-bending angle;

[0039] The regulating signal control unit outputs the solenoid valve regulating signal according to the air pressure, angle and finger pressure output values ​​to control the pneumatic soft hand robot to perform various bending shapes.

[0040] The upper cavity structure of the main bending module includes a plurality of semicircular cross-section air cavities arranged in sequence, and each group of two adjacent semicircular cross-section air cavities is connected through the gas channel of the main bending module. After gas is introduced into each semicircular cross-section air cavity, the main bending module can realize the main bending function of the soft hand robot; after the upper cavity structure of the main bending module is pressurized, the terminal fingertips can reach a bending angle of 180°.

[0041] The lower cavity structure of the reverse bending module includes a plurality of trapezoidal cross-section air cavities arranged in parallel, and two adjacent trapezoidal cross-section air cavities are connected through the gas channel of the reverse bending module. After gas is introduced into each trapezoidal cross-section air cavity, the reverse bending module can realize the reverse bending of the soft hand robot; after the lower cavity structure of the reverse bending module is pressurized, the end fingertips can reach a bending angle of 70°.

[0042] The intermediate air pipe connection layer includes a connecting plate and a plurality of air pipes arranged on the connecting plate. The two sides of the connecting plate are respectively sealed and connected to the main bending module and the reverse bending module. The plurality of air pipes supply air to the upper cavity structures of the main bending module and the lower cavity structure of the reverse bending module respectively. The upper side surface of the connecting plate is provided with a plurality of main bending module ventilation holes respectively connected to the upper cavity structures. The lower side surface of the connecting plate is provided with reverse bending module ventilation holes connected to the lower cavity structure.

[0043] The fingertip force of the reverse bending module is smaller than the fingertip force of the main bending module. The main bending module, the middle trachea connection layer and the reverse bending module are all made of silicone material.

[0044] The advantages and beneficial effects of the present invention compared with the prior art are:

[0045] 1. Conform to human hand bionics: The pneumatic soft hand robot provided by the present invention has a structural design that conforms to the bending and stretching form of the human hand, and the reverse bending module can better fit the movement of the fingers.

[0046] 2. Better safety: The present invention drives the soft hand robot by pneumatic drive, and can realize the rehabilitation movement of fingers under safe air pressure. It has been verified by experiments that the reverse bending fingertip force is smaller than the main bending fingertip force, thus ensuring safety.

[0047] 3. Large finger flexion angle: The main bending module of the present invention adopts a twelve-cavity structure, and the fingertips can reach a 180° bending angle after pressurization. The fingertips of the reverse bending module can reach a 70° bending angle, meeting the requirements of finger bending.

[0048] 4. Multiple rehabilitation gestures: The present invention can realize multiple bending shapes of fingers by controlling different joints of the soft hand robot, and can assist the fingers to complete stretching movements, ultimately meeting the needs of multiple rehabilitation training.

[0049] 5. Auxiliary function: After testing, the maximum load capacity of a single finger of the present invention is 260g under 130Kpa, which can assist patients with hand injuries to grasp objects of suitable weight.

[0050] 6. Easy to expand: This hardware platform adopts the simplest construction method to realize the control of bidirectional bending soft hand rehabilitation robot, which makes it easy to realize more complex functions based on it.

[0051] 7. Fully functional: Through this hardware platform, individual and collaborative training of fingers can be realized, and finger stretching exercises can be completed. This increases the number of hand rehabilitation postures and realizes auxiliary tasks. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 This is a schematic diagram of the hardware platform system of the present invention;

[0053] Figure 2 This is an axonometric diagram of a pneumatic soft hand robot of the present invention;

[0054] Figure 3 This is an axonometric diagram of the composition structure of a pneumatic soft hand robot of the present invention;

[0055] Figure 4 One of the axonometric views of the main bending module in the present invention;

[0056] Figure 5 This is the second axonometric drawing of the main bending module in the present invention;

[0057] Figure 6 This is one of the axonometric views of the intermediate air pipe connection layer in the present invention;

[0058] Figure 7 This is the second axonometric view of the intermediate air pipe connection layer in the present invention;

[0059] Figure 8 One of the axonometric views of the reverse bending module of the present invention;

[0060] Fig. 9 This is the second axonometric view of the reverse bending module in the present invention;

[0061] Fig.10 It is a structural schematic diagram of a middle finger mold in one embodiment of the present invention;

[0062] Fig.11 It is a structural schematic diagram of a thumb mold in another embodiment of the present invention;

[0063] Fig.12 It is a gas path diagram of the hardware platform of the present invention;

[0064] Fig.13 The circuit diagram of the voltage reduction module of the hardware platform of the present invention is

[0065] Fig.14 is a circuit diagram of the Arduino controller of the present invention;

[0066] Fig.15 The circuit diagram of the motor drive module of the hardware platform of the present invention;

[0067] Fig.16 The circuit diagram of the air pressure sensor and relay of the hardware platform of the present invention.

[0068] In the figure: 101-semicircular cross-section air cavity, 102-main bending module gas channel, 103-trachea, 104-main bending module ventilation hole, 105-reverse bending module ventilation hole, 106-trapezoidal cross-section air cavity, 107-reverse bending module gas channel, 108-main bending module, 109-intermediate trachea connecting layer, 110-reverse bending module, 111-connecting plate;

[0069] 201-main bending module lower part mold Ⅰ, 202-main bending module upper part mold Ⅰ, 203-middle tracheal layer main bending surface mold Ⅰ, 204-middle tracheal layer reverse bending surface mold Ⅰ, 205-reverse bending module upper part mold Ⅰ, 206-reverse bending module lower part mold Ⅰ, 207-main bending module lower part mold Ⅱ, 208-main bending module upper part mold Ⅱ, 209-middle tracheal layer main bending surface mold Ⅱ, 210-middle tracheal layer reverse bending surface mold Ⅱ, 211-reverse bending module lower part mold Ⅱ, 212-reverse bending module upper part mold Ⅱ;

[0070] 301-controller, 302-motor driver, 303-air pump, 304-relay, 305-two-position two-way solenoid valve, 306-air pressure sensor, 307-pressure reducing module, 308-overflow valve, 309-two-position three-way solenoid valve, 310-cylinder, 311-PWM pin, 312-I / O interface, 313-analog interface, 314-output voltage end of the pressure reducing module, 315-pneumatic soft hand robot (pneumatic soft glove), 316-motor (simulated air pump), 317-diode, 318-pull-up resistor, 319-button, 320-main air path of the main bending air path, 321-main air path of the reverse bending air path. DETAILED DESCRIPTION

[0071] In order to have a further understanding of the features, purposes and functions of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0072] The pneumatic soft hand robot system structure diagram mainly consists of two parts, including the soft hand rehabilitation robot and its control circuit. Figure 1 shown.

[0073] See also Figure 2 , Figure 3 As shown, the present invention provides a pneumatic soft hand robot, including a main bending module 108, an intermediate air pipe connecting layer 109 and a reverse bending module 110 connected in sequence from top to bottom, wherein the main bending module 108 is provided with two or three groups of upwardly protruding and independent upper cavity structures, the reverse bending module 110 is provided with a downwardly protruding lower cavity structure, the intermediate air pipe connecting layer 109 is used to connect the main bending module 108 and the reverse bending module 110, and provide air pressure for the lower cavity structure and each upper cavity structure, so as to realize the bending and stretching movements of the pneumatic soft hand robot.

[0074] See also Figure 4 , Figure 5 As shown, in an embodiment of the present invention, the upper cavity structure of the main bending module 108 includes a plurality of semicircular cross-section air cavities 101 arranged in sequence, and each group of two adjacent semicircular cross-section air cavities 101 are connected through a main bending module gas channel 102. After gas is introduced into each semicircular cross-section air cavity 101, the main bending module 108 can realize the main bending function of the soft hand robot.

[0075] In this embodiment, each upper cavity structure is provided with four semicircular cross-section air cavities 101, and after the upper cavity structure of the main bending module 108 is pressurized, the distal fingertip can reach a bending angle of 180°.

[0076] See also Figure 8 , Fig. 9As shown, in an embodiment of the present invention, the lower cavity structure of the reverse bending module 110 includes a plurality of trapezoidal cross-section air cavities 106 arranged in parallel, and two adjacent trapezoidal cross-section air cavities 106 are connected through a reverse bending module gas channel 107. After gas is introduced into each trapezoidal cross-section air cavity 106, the reverse bending module 110 can realize reverse bending of the soft hand robot.

[0077] Furthermore, after the lower cavity structure of the reverse bending module 110 is pressurized, the end fingertip can reach a bending angle of 70°. The fingertip force of the reverse bending module 110 is smaller than the main bending fingertip force of the main bending module 108 .

[0078] See also Figure 6 , Figure 7 As shown, in an embodiment of the present invention, the intermediate air pipe connecting layer 109 includes a connecting plate 111 and a plurality of air pipes 103 arranged on the connecting plate 111, and the two sides of the connecting plate 111 are respectively sealed and connected to the main bending module 108 and the reverse bending module 110, and the plurality of air pipes 103 respectively supply air to the upper cavity structures of the main bending module 108 and the lower cavity structures of the reverse bending module 110.

[0079] Furthermore, the upper side of the connecting plate 111 is provided with a plurality of main bending module ventilation holes 104 respectively connected to the upper cavity structures; the lower side of the connecting plate 111 is provided with a reverse bending module ventilation hole 105 connected to the lower cavity structure. The reverse bending module ventilation hole 105 and each main bending module ventilation hole 104 are respectively connected to an air pipe 103. In this embodiment, there are four air pipes 103. By controlling the air pressure in each upper cavity structure of the main bending module 108, a variety of bending forms of the pneumatic soft hand robot can be achieved.

[0080] Specifically, the main bending module 108 is the upper layer of the finger, which is mainly responsible for the flexion movement of the finger. It is a three-level cavity structure designed to simulate the three joints of the finger. Each joint has four semicircular cross-section air cavities 101. The cross-sectional shape of the semicircular cross-section air cavity 101 is a semicircle, which has better bending performance. The reverse bending module 110 is the lower layer of the finger, which is mainly responsible for the extension movement of the finger. The cross-sectional design is trapezoidal. Under the condition of not affecting the main bending and safety of the finger, the cross-sectional shape of the trapezoidal cross-section air cavity 106 adopts a trapezoidal shape, which can provide a sufficiently large reverse bending force. The intermediate tracheal connection layer 109 is an intermediate layer, the purpose of which is to place the trachea 103, and to transport air to the main bending module 108 and the reverse bending module 110 through the main bending module ventilation holes 104 and the reverse bending module ventilation holes 105, respectively, and will play a connecting role.

[0081] In the embodiment of the present invention, the main bending module 108, the intermediate air tube connection layer 109 and the reverse bending module 110 are all made of silicone material. When the main bending module 108 is provided with three groups of upwardly protruding and independent upper cavity structures, a middle finger is formed with twelve semicircular cross-sectional air cavities 101; when the main bending module 108 is provided with two groups of upwardly protruding and independent upper cavity structures, a thumb is formed with eight semicircular cross-sectional air cavities 101.

[0082] Specifically, the middle finger is prepared using a middle finger mold. Fig.10 As shown, the middle finger mold consists of six parts: the lower part mold Ⅰ201 of the main bending module, the upper part mold Ⅰ202 of the main bending module, the main bending surface mold Ⅰ203 of the intermediate air tube layer, the reverse bending surface mold Ⅰ204 of the intermediate air tube layer, the upper part mold Ⅰ205 of the reverse bending module and the lower part mold Ⅰ206 of the reverse bending module. Fig.10 As shown in (A), the main bending module lower part mold Ⅰ201 and the main bending module upper part mold Ⅰ202 are used to prepare the main bending module 108 of the middle finger; see Fig.10 As shown in (B), the intermediate tracheal layer main curved surface mold Ⅰ203 and the intermediate tracheal layer reverse curved surface mold Ⅰ204 are used to prepare the intermediate tracheal connecting layer 109 of the middle finger; see Fig.10 As shown in (C), the reverse bending module upper part mold I 205 and the reverse bending module lower part mold I 206 are used to prepare the reverse bending module 110 of the middle finger.

[0083] Specifically, the thumb is prepared using a thumb mold. Fig.11 As shown, the thumb mold consists of six parts, including the main bending module lower part mold Ⅱ207, the main bending module upper part mold Ⅱ208, the middle tracheal layer main bending surface mold Ⅱ209, the middle tracheal layer reverse bending surface mold Ⅱ210, the reverse bending module lower part mold Ⅱ211 and the reverse bending module upper part mold Ⅱ212. Fig.11 As shown in (a), the main bending module lower part mold II 207 and the main bending module upper part mold II 208 are used to prepare the main bending module 108 of the thumb; see Fig.11 As shown in (b), the middle tracheal layer main curved surface mold II 209 and the middle tracheal layer reverse curved surface mold II 210 are used to prepare the middle tracheal connecting layer 109 of the thumb; see Fig.11 As shown in (c), the reverse bending module lower part mold II 211 and the reverse bending module upper part mold II 212 are used to prepare the reverse bending module 110 of the thumb.

[0084] The present invention provides a pneumatic soft hand robot. Taking the middle finger as an example, the preparation process is as follows:

[0085] The mold material is PLA, which is printed by Bambu Lab 3D printer. The pneumatic soft hand robot is made of Ecoflex 00-50 silicone in a 1:1 ratio.

[0086] The manufacturing process of the main bending module 108 is: cover the main bending module upper part mold Ⅰ202 on the main bending module lower part mold Ⅰ201, then pour the stirred silicone compound into the mold, let it stand for three hours, and then demould.

[0087] The production process of the intermediate air tube connecting layer 109 is: first place the air tube 103 into the corresponding hole, then pour the silicone material into the intermediate air tube layer main curved surface mold Ⅰ203, and finally cover the intermediate air tube layer reverse curved surface mold Ⅰ204 on the intermediate air tube layer main curved surface mold Ⅰ203 and fix it. After standing for three hours, demold it.

[0088] The reverse bending module 110 is manufactured by an inverted casting method: first, a silicone compound is poured into the reverse bending module lower part mold Ⅰ206, and then the reverse bending module upper part mold Ⅰ205 is covered on the reverse bending module lower part mold Ⅰ206. Finally, it is inverted, with the reverse bending module lower part mold Ⅰ206 on top, and cast again, left to stand for three hours, and demoulding.

[0089] Finally, glue the three parts together to get the middle finger. The production process of the thumb is the same as that of the middle finger.

[0090] In this embodiment, the mathematical model of the main bending module 108 is

[0091] The length of the unit air cavity module is a, the expanded length of the module after inflation is b, the height is h, the bending angle is θ, the width of the module is c, and the error caused by environmental factors is E. The bending angle θ is given by the following formula:

[0092]

[0093] According to Avogadro's hypothesis, the equilibrium equation for gas volume and mass can be derived from Clapham's equation:

[0094]

[0095] Where P (Pa) is the pressure, V (m 3 ) is the volume, m(g) is the mass, μ(g / mol) is the molar mass, T(℃) is the absolute temperature, and R is a constant.

[0096] When the cavity is inflated, a single air cell can be regarded as a semi-ellipsoid. Therefore, the volume expression of a single inflated air cell is as follows:

[0097]

[0098] According to equations (1)-(3), the relationship between the output air pressure and the bending angle is obtained.

[0099]

[0100] In this embodiment, the mathematical model of the reverse bending module 110 is

[0101] In order to meet the requirements of reverse bending without affecting the finger flexion angle, the middle part is designed as an isosceles trapezoid, and the side is an irregular trapezoid with the same inclination angle. The height of the reverse bending module 110 is h1, the length of the upper base is b1, the length of the lower base is a1, the angle between the lower base and the side of the trapezoid is α1, and the width of the module is c.

[0102]

[0103] Among them, t is the hypotenuse of the trapezoid; R is the radius of the fan after expansion; ε is half of the central angle; θ is half of the bending angle.

[0104] When the cavity is expanded, a single chamber can be represented as:

[0105] V=2εR 2 c-Rtccosε+(a1+b1)h1c / 2 (6)

[0106] According to Avogadro's hypothesis, the equilibrium equation for gas volume and mass can be derived from Clapham's equation:

[0107]

[0108] Where P'(Pa) is the pressure, V(m 3 ) is the volume, m0(g) is the mass, μ0(g / mol) is the molar mass, T0(℃) is the absolute temperature, and R0 is a constant.

[0109] According to equations (5)-(7), the relationship between the output air pressure and the bending angle is obtained.

[0110]

[0111] The present invention proposes a novel flexible pneumatic hand rehabilitation robot equipped with a bidirectional bending actuator, the maximum bending angle of the thumb can reach 70°, and the maximum bending angle of other fingers can reach 180°, which can meet the needs of daily activities. The main bending module 108 realizes the finger flexion function, adopts a three-level cavity structure, and is designed with a total of twelve air cavities. Each finger joint contains four air cavities to simulate human fingers. Each joint can be controlled individually or collaboratively, and such a design increases the finger training movement. The intermediate tracheal connection layer 109 is used to fix the trachea 103 and connect the main bending module 108 and the reverse bending module 110. The surface with three air holes is bonded to the main bending module 108, and the surface with one air hole is bonded to the reverse bending module 110. Without affecting the bending movement of the main bending module 108, the reverse bending module 110 uses a trapezoidal air chamber structure. This configuration conforms to the bending form of the human hand and can improve the reverse bending ability to achieve the function of assisting finger extension.

[0112] The present invention can realize the rehabilitation movement of fingers under safe air pressure. After experimental verification, the force of the reverse bending fingertips is less than the force of the main bending fingertips, which shows the safety of the fingers. The maximum weight that the fingers can grasp is 260g. This is particularly beneficial for the rehabilitation of patients with partial hand dysfunction. The present invention can not only complete a variety of hand rehabilitation postures, but also assist patients with hand injuries to grasp objects of suitable weight, which can better help the recovery of hand function.

[0113] The control circuit includes: a controller 301 and a main bending circuit, a reverse bending circuit, and an air path connection circuit respectively connected thereto; the main bending circuit and the reverse bending circuit are both connected to the air path circuit; the air path circuit includes an air pump 303 and a motor driver 302, and the air pump 303 is also connected to the intermediate air pipe connection layer 109 of the pneumatic soft hand robot; the controller is burned with an inflation program, and outputs instructions to control the main bending circuit, the reverse bending circuit, and the air path connection circuit to work, so that the air pump 303 inflates the main bending module 108 and the reverse bending module 110 through the intermediate air pipe connection layer, thereby realizing the bending and stretching movements of the pneumatic soft hand robot.

[0114] Specifically, in the control circuit, the Arduino controller 301 is mainly responsible for sending or receiving instructions. The motor driver 302 is connected to the air pump 303, and is mainly responsible for receiving the instructions of the Arduino controller to provide an air source to the air circuit. The relay 304 is mainly responsible for receiving the instructions of the Arduino controller, and controlling the two-position two-way solenoid valve 305 and the two-position three-way solenoid valve 309 to realize the opening and closing of each air circuit of the main bending module 108 and the reverse bending module 110. The two-way inflation branch air circuit controls the inflation and deflation of the main bending module and the reverse bending module of a single finger respectively. A total of 10 circuit branches work for five fingers of a single hand. The air pressure sensor 306 is connected to the inflation pipeline directly connected to the main bending module and the reverse bending module of each finger or the main air circuit 320 of the main bending air circuit of each finger and the main air circuit 321 of the reverse bending air circuit, and is mainly used to detect the real-time pressure value of each inflation pipeline and receive the detection data through the Arduino controller. The step-down module 307 is used to reduce the external +12V power supply to +5V power supply to the Arduino controller 301. The input end of the overflow valve 308 is connected to the air outlet of the air pump, and the output end of the overflow valve 308 is connected to the inflation gas path, the purpose of which is to ensure the safety of the entire system by controlling the flow of gas input. The data collected by the finger angle bending sensor and the finger pressure sensor are also used as a basis for judging the finger movement state.

[0115] like Fig.12 As shown, the main bending air circuit and the reverse bending air circuit have the same structure, and each includes five air-charging branches. The relay 304 and the two-position two-way solenoid valve 305 form an air-charging branch, and +12V is used as a power supply. The main bending air circuit controls the opening and closing of the relay 304 through the Arduino controller 301, and then controls the opening and closing of the two-position two-way solenoid valve 305 and the two-position three-way solenoid valve 309. The air pump 303 provides air to control the inflation of the soft hand rehabilitation robot 315 or the movement of the cylinder 310 (simulating the soft hand rehabilitation robot). The reverse bending air circuit controls the opening and closing of the relay 304 through the Arduino controller 301, and then controls the opening and closing of the two-position two-way solenoid valve 305. The air pump 303 provides air to control the inflation of the soft hand rehabilitation robot 315 or the movement of the cylinder 310 (simulating the soft hand rehabilitation robot). The main bending air circuit and the reverse bending air circuit have a common intermediate connecting air circuit part. The input end of the relief valve 308 is connected to the air outlet of the air pump, and the output end of the relief valve 308 is connected to the inflation air circuit, so as to ensure the safety of the whole system by controlling the flow rate of gas input.

[0116] The a end of the intermediate connecting gas path is connected to the 305A end of the main curved gas path, and the b end is connected to the 305B end of the reverse curved gas path. There are 5 intermediate connecting gas paths in total, connecting (YAZ1, YAF1) to (YAZ5, YAF5).

[0117] Fig.13The step-down module 307 reduces the external +12V power supply to +5V and provides it to the Arduino controller 301. The inductor L1 can convert electrical energy into magnetic energy for storage, and can also convert magnetic energy into electrical energy for release again. In addition, it also protects the current so that it gradually increases; in order to prevent a large transient voltage from appearing at the input end, an aluminum or tantalum capacitor (C1, C2) is added between the input end and the ground as a bypass capacitor; the Schottky diode D6 ensures the direction of the current.

[0118] Fig.14 The Arduino controller 301 is an Arduino controller. The Arduino controller 301 outputs a motor driving signal to the motor driver 302 via a PWM pin, thereby controlling the operation of the air pump motor 316 and making the air pump 303 work. The Arduino controller 301 outputs an inflation signal to the two-position two-way solenoid valve 305 via an I / O interface 312 of the Arduino controller 301, thereby adjusting the opening of the solenoid valve to control the output air pressure of the air pump. The analog interface 313 of the Arduino controller 301 receives the real-time air pressure measurement signal of the air pressure sensor 306.

[0119] like Fig.15 As shown, the motor driver 302 receives the motor drive signal and controls the motor M1 (simulating the air pump) and the motor M2 (simulating the air pump) to work through two groups of output pins (OUT1 and OUT 2, OUT3 and OUT 4). The circuit is also equipped with a pull-up resistor 318 and a button 319 to control the speed and direction of the motor M1 and the motor M2, and the diode 317 controls the current flow direction of the circuit.

[0120] like Fig.16 As shown, the air pressure sensor 306 is connected to the inflation pipeline of the main bending module and the reverse bending module of each finger or the main air path 320 of the main bending air path of each finger and the main air path 321 of the reverse bending air path, and is mainly used to detect the real-time pressure value of each inflation pipeline and receive the detection data through the Arduino controller. Since the switch valve can be driven by a digital signal, 10 relays 304 are connected to the I / O interface 312 of the Arduino controller 301 to control the opening and closing of the relay 304 to realize the opening and closing of the two-position two-way solenoid valve 305 or the two-position three-way solenoid valve 309. The relay 304 corresponding to each finger of the main air path 320 of the main bending air path controls the opening and closing of the two-position two-way solenoid valve 305 and the two-position three-way solenoid valve 309, and the relay 304 corresponding to each finger of the main air path 321 of the reverse bending air path controls the opening and closing of the two-position two-way solenoid valve 305.

[0121] The finger bending angle sensor is placed on the surface of the soft glove that contacts the back of the human finger, records the finger joint bending angle value when the pneumatic soft glove drives the human finger to bend, and transmits the angle data to the controller 301 as a basis for judging the finger movement state.

[0122] The finger film pressure sensor is placed on the fingertips of the distal knuckles of the soft glove to record the finger pressure value when the pneumatic soft glove drives the human finger to grasp an object, and transmits the pressure data to the controller 301 as a basis for judging whether the finger grasping movement has stopped.

[0123] In this example, a motor 316 is used to simulate an air pump. The motor driver 302 is connected to the I / O interface of the Arduino controller 301, and the speed and direction of the motor 316 are controlled by adjusting the duty cycle of the PWM signal. This regulation effectively regulates the airflow and pressure. In addition, the air pressure sensor 306 converts the pressure reading into an analog voltage signal. The main control board of the Arduino controller 301 captures the output through the A0 and A1 pins of the air pressure sensor 305.

[0124] The present invention proposes a hardware platform for a bidirectional pneumatic soft manipulator rehabilitation system. The platform is divided into two main parts: a pneumatic circuit and an electrical circuit. A method for effectively connecting these circuits is developed by integrating two air pumps, ten relays and 25 solenoid valves. The Arduino microcontroller plays a vital role in managing relays and solenoid valves and controlling motor drive modules. This setting can control the bending and extension movements of multiple fingers at the same time. The present invention can not only help users train a single finger, but also promote the coordinated movement of multiple fingers in a variety of rehabilitation gestures, and realize the control of the soft hand rehabilitation robot to assist hand-impaired patients in completing rehabilitation training and auxiliary tasks.

[0125] The above description is only an embodiment of the present invention and is not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, expansion, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims

1. A control method for a pneumatic soft hand robot, characterized in that: The following steps are involved: Step 1, real-time acquisition and recording of feedback signals and control signals of the pneumatic soft hand robot; the control and feedback signal data include air pressure signal data, finger angle signal data, finger pressure signal data, and control circuit signal data; the control circuit signal data include relay signals and solenoid valve opening signals; Step 2: Calculate the corresponding air pressure output value at a given target bending angle according to the mathematical model of air pressure-bending angle; Step 3: According to the air pressure, angle and finger pressure output values, the relay adjusts the signal to control the pneumatic soft hand robot to perform various bending shapes.

2. The control method of a pneumatic soft hand robot according to claim 1, characterized in that: The mathematical model of the main bending module (108) includes: Define the length of the unit air cavity module as a, the expanded length of the module after inflation as b, the height as h, the bending angle as θ, the width of the module as c, and the error caused by environmental factors as E, then the bending angle θ is: According to Avogadro's hypothesis, the equilibrium equation for gas volume and mass is derived from Clapham's equation: Where P (Pa) is the pressure, V (m 3 ) is volume, m(g) is mass, μ(g / mol) is molar mass, T(℃) is absolute temperature, and R is a constant; When the cavity of the main bending module (108) is expanded, a single air chamber is regarded as a semi-ellipsoid, and the volume expression of a single inflated air chamber is as follows: According to equations (1)-(3), the relationship between output air pressure and bending angle is obtained:

3. The control method of a pneumatic soft hand robot according to claim 1, characterized in that: The mathematical model of the reverse bending module (110) includes: In order to meet the requirement of reverse bending without affecting the finger flexion angle, the middle part is designed to be an isosceles trapezoid, and the side is an irregular trapezoid with the same inclination angle; the height of the reverse bending module (110) is h1, the length of the upper base is b1, the length of the lower base is a1, the angle between the lower base and the side of the trapezoid is α1, and the width of the module is c, then: Among them, t is the hypotenuse of the trapezoid; R is the radius of the fan after expansion; ε is half of the central angle; θ is half of the bending angle; When the reverse bending module (110) cavity is expanded, a single chamber is represented by: V=2εR 2 c-Rtccosε+(a1+b1)h1c / 2 (6) According to Avogadro's hypothesis, the equilibrium equation for gas volume and mass is derived from Clapham's equation: Where P'(Pa) is the pressure, V(m 3 ) is the volume, m0(g) is the mass, μ0(g / mol) is the molar mass, T0(℃) is the absolute temperature, and R0 is a constant; According to equations (5)-(7), the relationship between output air pressure and bending angle is obtained:

4. A control system for a pneumatic soft hand robot, characterized in that: The system is used to control the movement of a pneumatic soft hand robot; The pneumatic soft hand robot comprises: a main bending module (108), an intermediate air tube connection layer (109) and a reverse bending module (110) which are connected in sequence from top to bottom, wherein the main bending module (108) is provided with two or three groups of upper cavity structures which are raised upward and independent, the reverse bending module (110) is provided with a lower cavity structure which is raised downward, and the intermediate air tube connection layer (109) is used to connect the main bending module (108) and the reverse bending module (110), and to provide air pressure for the lower cavity structure and each upper cavity structure; The control circuit of the system comprises: a controller (301) and electrical components connected thereto for controlling a main bending air circuit and a reverse bending air circuit respectively; the working states of the main bending air circuit and the reverse bending air circuit are controlled by the electrical components; the power input end of the air pump (303) of the main bending air circuit and the reverse bending air circuit is connected to the motor driver (302), and the common intermediate connecting air circuit end of the main bending air circuit and the reverse bending air circuit is connected to the intermediate air pipe connecting layer (109) of the pneumatic soft hand robot; the controller (301) is built with various program units, and the various program units cooperate with each other to output instructions to control corresponding electrical components, thereby controlling the working states of the main bending air circuit and the reverse bending air circuit, and in combination with the air pump (303), inflating the main bending module (108) and the reverse bending module (110) through the intermediate air pipe connecting layer to achieve bending and stretching movements of the pneumatic soft hand robot.

5. The control system of a pneumatic soft hand robot according to claim 4, characterized in that: The control circuit also includes at least two air pressure sensors (306) connected to the controller; the air pressure sensor I is arranged in the main air path (320) of the inflation pipeline or the main bending air path directly connected to the main bending module (108); the air pressure sensor II is arranged in the main air path (321) of the inflation pipeline or the reverse bending air path directly connected to the reverse bending module (109); and is used to collect real-time inflation air pressure signal data.

6. The control system of a pneumatic soft hand robot according to claim 4, characterized in that: The electrical components for controlling the main bending air circuit and the reverse bending air circuit include an air pump (303), an overflow valve (308), a relay (304), a two-position two-way solenoid valve (305) and a two-position three-way solenoid valve (309), wherein the relay (304) is connected to the controller (301); the circuit structures of the main bending circuit and the reverse bending circuit are the same, and both include: five branches composed of the relay (304) and the two-position two-way solenoid valve (305), which respectively control the forward bending and reverse bending of the five fingers; the relays (304) are connected to the controller (301), and the controller (301) outputs a signal to each relay (304) so ​​that the two-position two-way solenoid valve (305) in each branch of the main bending circuit and each branch of the reverse bending circuit is powered on; the two-position two-way solenoid valve (305) in the main bending circuit respectively controls the two-position three-way solenoid valve (309), and the two-position two-way solenoid valve (305) in the main bending circuit controls the two-position three-way solenoid valve (309) through the main bending circuit. The air circuit is connected to the main bending module (108) of the pneumatic soft robot (315); the two-position two-way solenoid valve (305) of the reverse bending circuit is connected to the reverse bending module (110) of the pneumatic soft robot (315) through the reverse bending air circuit; the main bending air circuit and the reverse bending air circuit are both connected to an air pump (303); the controller (301) outputs a signal to each two-position two-way solenoid valve (305) to adjust the valve opening, and outputs a signal to the motor driver (302) to control the operation of the air pump (303) and adjust the flow rate of the gas output by the air pump (303), and provide air pressure to the upper cavity structure and each lower cavity structure of the main bending module (108) and the reverse bending module (110); the input end of the overflow valve (308) is connected to the air outlet of the air pump, and the output end of the overflow valve (308) is connected to the inflation air circuit to release the excess air pressure of the system and keep the air pressure of the system constant.

7. The control system of a pneumatic soft hand robot according to claim 4, characterized in that: Each program unit includes: The signal acquisition and recording unit acquires and records the feedback signal and control signal of the pneumatic soft hand robot in real time; the control and feedback signal data include air pressure signal data, finger angle signal data, finger pressure signal data, and control circuit signal data; the control circuit signal data include relay signal and solenoid valve opening signal; A model calculation unit calculates the corresponding air pressure output value at a given target bending angle according to a mathematical model of air pressure-bending angle; The regulating signal control unit outputs the solenoid valve regulating signal according to the air pressure, angle and finger pressure output values ​​to control the pneumatic soft hand robot to perform various bending shapes.

8. The control system of a pneumatic soft hand robot according to claim 4, characterized in that: The upper cavity structure of the main bending module (108) comprises a plurality of semicircular cross-section air cavities (101) arranged in sequence, and each group of two adjacent semicircular cross-section air cavities (101) are connected via a main bending module gas channel (102). After gas is introduced into each semicircular cross-section air cavity (101), the main bending module (108) can realize the main bending function of the soft hand robot; after the upper cavity structure of the main bending module (108) is pressurized, the distal fingertips can reach a bending angle of 180°.

9. The control system of a pneumatic soft hand robot according to claim 4, characterized in that: The lower cavity structure of the reverse bending module (110) comprises a plurality of trapezoidal cross-section air cavities (106) arranged in parallel, and two adjacent trapezoidal cross-section air cavities (106) are connected via a reverse bending module gas channel (107). After gas is introduced into each trapezoidal cross-section air cavity (106), the reverse bending module (110) can realize reverse bending of the soft hand robot; after the lower cavity structure of the reverse bending module (110) is pressurized, the end fingertips can reach a bending angle of 70°.

10. The control system of a pneumatic soft hand robot according to claim 4, characterized in that: The intermediate air pipe connection layer (109) comprises a connection plate (111) and a plurality of air pipes (103) arranged on the connection plate (111); the two sides of the connection plate (111) are respectively sealed and connected to the main bending module (108) and the reverse bending module (110); the plurality of air pipes (103) respectively supply air to the upper cavity structures of the main bending module (108) and the lower cavity structure of the reverse bending module (110); the upper side surface of the connection plate (111) is provided with a plurality of main bending module ventilation holes (104) respectively connected to the upper cavity structures; and the lower side surface of the connection plate (111) is provided with reverse bending module ventilation holes (105) connected to the lower cavity structure.

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