Software contact force sensor, method of manufacture and exoskeleton robot

Abstract

The application provides a soft contact force sensor, a preparation method and an exoskeleton robot, and belongs to the technical field of sensing and detection, and is used for solving the problem that the air bag type flexible contact force sensor can only perceive a single direction. The soft contact force sensor provided by the application comprises a base shell, a soft air bag, a first pressure sensor, at least one second pressure sensor and a controller. The soft contact force sensor can detect a positive pressure value through the soft air bag and the first pressure sensor, and can detect a tangential force value through the second pressure sensor, so that the two-dimensional force perception function is realized while the comfort of a wearer is ensured.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of sensing and detection, and particularly relates to a soft contact force sensor, a preparation method and an exoskeleton robot. BACKGROUND

[0002] In the actual use of the upper limb exoskeleton robot, the wearer and the robot body structure will frequently contact, and a contact force signal is generated at the physical human-machine interaction interface. The contact force signal is often combined with impedance control algorithm to enhance the controllability of the upper limb exoskeleton robot. Therefore, for the upper limb exoskeleton robot, the contact force sensor used thereby should not only consider the measurement accuracy, but also ensure the long-term comfort of the wearer in the use process. The existing contact force sensors are mostly rigid force sensors. Due to the characteristics of high cost, large mass, high stiffness coefficient and poor flexibility, the wearer is prone to have a repulsive feeling in the use process. In view of the poor flexibility and low comfort of the rigid force sensor, an effective method is to use a flexible non-metallic material to manufacture a new type of soft contact force sensor. Non-metallic materials such as silicone rubber and engineering plastic have the characteristics of small mass, high flexibility and strong shock resistance, and are widely used in wearable electronic devices such as smart bracelets and intelligent prosthetic systems. At present, the soft contact force sensor is mainly divided into two types according to the different force measurement principles. One is a soft electronic skin, and the other is a gas bag type contact force sensor. The soft electronic skin uses graphene and other materials as a sensitive element, and uses silicone rubber material as a substrate layer. The soft electronic skin has a low thickness and high ductility, and can be used to detect the tensile and bending force of the surface of an object, and improve the sensing ability of the object. However, the soft electronic skin has the following disadvantages: the body structure and the preparation process are relatively complex, the force measurement range is small, and the reliability is poor, so it cannot meet the use requirements of the upper limb exoskeleton robot. In addition, for the exoskeleton robot, the soft electronic skin has a relatively thin thickness, and it is difficult to provide a buffer space for the wearer. When the contact force is too large, the wearer is prone to have an uncomfortable feeling. The gas bag type contact force sensor uses a sealed silicone rubber gas bag as a sensitive element. When an external force is loaded on the surface of the gas bag, the gas pressure of the gas bag will change obviously. In addition, the soft silicone rubber gas bag has a certain thickness, and can provide a certain buffer for the arm of the wearer when the contact force is large, thereby increasing the safety of the upper limb exoskeleton robot. However, the gas bag type flexible contact force sensor has the following two problems: first, the gas port of the silicone rubber gas bag is prone to leakage, which makes it difficult to be widely used in the upper limb exoskeleton robot; and second, the gas bag type flexible contact force sensor can only sense the contact force in a single direction (i.e. the vertical pressure), and cannot sense the contact force in multiple dimensions. SUMMARY

[0003] The present application aims to at least solve one of the problems in the prior art or related art.

[0004] In a first aspect, a soft contact force sensor is provided, comprising: a base shell, a soft airbag, a first pressure sensor, at least one second pressure sensor, and a controller. The base shell is for mounting on an exoskeleton robot. The base shell includes a receiving groove. The soft airbag is housed in the receiving groove. The upper part of the soft airbag protrudes from the top of the receiving groove for contact with a wearer. The soft airbag has a sprue. The signal input terminal of the first pressure sensor is sealed to the sprue via a connector. The second pressure sensor is disposed between the side wall of the receiving groove and the soft airbag. The controller is connected to the signal output terminals of the first pressure sensor and the second pressure sensor, respectively. The controller is capable of acquiring a contact force value based on the pressure signals from the first and second pressure sensors and sending the contact force value to a host computer.

[0005] Optionally, a first through hole is provided on the side wall of the receiving tank. A protrusion is included on the surface of the soft airbag. The protrusion extends into the first through hole. The sprue passes through the end face of the protrusion into the soft airbag.

[0006] Optionally, the connector includes a large-diameter section and a small-diameter section connected in sequence. A retaining flange is provided at the connection between the large-diameter section and the small-diameter section. The large-diameter section is inserted into the first through hole and surrounds the protrusion inside. The inner wall of the large-diameter section is sealed to the side wall of the protrusion. The outer diameter of the retaining flange is larger than the diameter of the first through hole. The retaining flange fits against the outer wall of the receiving groove. The small-diameter section is connected to the signal input terminal of the first pressure sensor via a flexible hose.

[0007] Optionally, the base housing also includes at least one second through-hole. The second pressure sensor includes a pressure-sensitive resistor and a signal amplifier. The pressure-sensitive resistor is disposed between the sidewall of the receiving groove and the soft airbag. The signal output terminal of the pressure-sensitive resistor is connected to a signal line. The signal line extends through the second through-hole to the outside of the receiving groove and is connected to the input terminal of the signal amplifier. The output terminal of the signal amplifier is connected to a controller.

[0008] Optionally, the base housing also includes a base plate. A receiving groove is provided on the base plate. The base plate has multiple threaded holes.

[0009] Secondly, a method for fabricating the aforementioned soft contact force sensor is provided, comprising the following steps:

[0010] The dimensions of the base shell and soft airbags are determined based on the dimensions of the physical human-computer interaction interface on the exoskeleton robot.

[0011] Prepare airbag molds according to the dimensions of soft airbags.

[0012] Soft airbags are produced by injection molding using an airbag mold.

[0013] Connectors are made using 3D printing.

[0014] Create a base shell and install the soft airbag inside the base shell.

[0015] The soft airbag, connector, and other components are assembled to form a soft contact force sensor.

[0016] Optionally, the airbag mold includes: a mold base, a front mold and a rear mold, a mold core, and end caps. The mold base has slots. The front mold and the rear mold interlock and are inserted into the slots. A mold cavity is formed between the front mold and the rear mold. The mold cavity has an injection port. The mold core is located within the mold cavity. A gap is formed between the surface of the mold core and the inner wall of the mold cavity. The gap is adapted to the wall thickness of the soft airbag. The melting point of the mold core is lower than the melting point of the soft airbag. End caps are fastened to the ends of the front and rear molds furthest from the mold base.

[0017] Soft airbags are manufactured using an airbag mold and injection molding process, including:

[0018] Prepare the silica gel stock solution and coagulant, stir, and let stand for the first preset time in a laboratory environment.

[0019] A vacuum pump is used to remove air bubbles from the mold cavity.

[0020] Inject the prepared silicone stock solution and coagulant into the mold cavity.

[0021] After waiting for the second preset time in a laboratory environment, the mold is disassembled to obtain the soft airbag.

[0022] After heating the soft airbag until the mold core melts, the mold core is extracted from the soft airbag.

[0023] Optionally, the mold core is made of paraffin wax and is produced by injection molding.

[0024] Thirdly, an exoskeleton robot is provided, comprising: an exoskeleton robot body and at least one of the aforementioned soft contact force sensors. The exoskeleton robot body includes at least one physical human-machine interface. Each soft contact force sensor is disposed on a physical human-machine interface for contacting the wearer to obtain the contact force between the wearer and the physical human-machine interface during movement.

[0025] Optionally, the exoskeleton robot body includes: an upper arm support, a forearm support, a support member, artificial pneumatic muscles, and a pair of physical human-machine interfaces. The upper arm support includes an arm rest. One end of the forearm support is hinged to the upper arm support, and the other end has a handle. The support member is telescopically connected between the upper arm support and the forearm support. The artificial pneumatic muscles are telescopically connected between the upper arm support and the forearm support. The pair of physical human-machine interfaces are located above and below the forearm support, respectively.

[0026] Beneficial effects

[0027] 1. In the embodiments of the present invention, the soft contact force sensor is mounted on an exoskeleton robot via a base shell. The upper part of the soft airbag protrudes from the top of the receiving groove for contact with the wearer. When the wearer contacts the soft airbag, the contact force compresses the volume of the soft airbag, causing a change in its internal air pressure. A first pressure sensor connected to the soft airbag can acquire the positive pressure, while a second pressure sensor located between the side wall of the receiving groove and the soft airbag can acquire the tangential force. The controller can then calculate the contact force value based on the positive pressure and the tangential force and send it to the host computer. The soft contact force sensor provided in this embodiment can detect the positive pressure value through the soft airbag and the first pressure sensor, and detect the tangential force value through the second pressure sensor, realizing two-dimensional force sensing while ensuring the comfort of the wearer.

[0028] 2. The fabrication method provided in the embodiments of the present invention can produce the above-mentioned soft contact force sensor, thus improving the comfort of the wearer when wearing the exoskeleton robot. The soft contact force sensor prepared by this method can perfectly fit the exoskeleton robot and is suitable for mass production, which helps to reduce the manufacturing cost of the soft contact force sensor.

[0029] 3. The exoskeleton robot provided in the embodiments of the present invention is equipped with the above-mentioned soft contact force sensor, which can improve the comfort of the wearer and make it more acceptable to the wearer. Attached Figure Description

[0030] Figure 1 A schematic diagram of the structure of a soft contact force sensor according to an embodiment of this application;

[0031] Figure 2 A partial structural cross-sectional view of a soft contact force sensor according to an embodiment of this application;

[0032] Figure 3 A schematic diagram of the connector structure of one embodiment provided in this application;

[0033] Figure 4 A cross-sectional view of a connector according to one embodiment of this application;

[0034] Figure 5 A force diagram of a soft airbag according to an embodiment of this application;

[0035] Figure 6 A flowchart of a preparation method provided in this application;

[0036] Figure 7 A flowchart of a preparation method for another embodiment provided in this application;

[0037] Figure 8 A schematic diagram of the structure of an airbag mold according to an embodiment of this application;

[0038] Figure 9 An exploded view of the structure of an airbag mold according to an embodiment of this application;

[0039] Figure 10 A schematic diagram of the mold structure of a mold core according to an embodiment of this application;

[0040] Figure 11 This is a schematic diagram of the structure of an exoskeleton robot according to an embodiment of this application.

[0041] The reference numerals in the attached figures are as follows:

[0042] 1. Base shell; 11. Receiving groove; 12. Base plate; 13. First through hole; 14. Second through hole; 15. Threaded hole;

[0043] 2. Soft airbag; 21. Protrusion; 22. Sprue; 23. Outline of the soft airbag before being subjected to force; 24. Outline of the soft airbag after being subjected to force;

[0044] 3. Connector; 31. Large diameter section; 32. Flange; 33. Small diameter section;

[0045] 4. Second pressure sensor; 41. Piezoresistive resistor; 42. Signal amplifier;

[0046] 5. Hose;

[0047] 6. First pressure sensor;

[0048] 7. Controller;

[0049] 8. Physical human-computer interaction interface; 81. Upper physical human-computer interaction interface; 82. Lower physical human-computer interaction interface;

[0050] 9. Airbag mold; 91. End cap; 911. Front end cap; 912. Rear end cap; 913. Injection port; 92. Rear mold; 93. Front mold; 94. Mold base; 95. Mold core; 951. Main body; 952. Sprue; 953. Protrusion; 96. Mold cavity; 97. Mold core mold; 971. First chamber; 972. Second chamber; 973. Third chamber;

[0051] 10. Exoskeleton robot body; 101. Upper arm support; 1011. Upper arm strut; 1012. Arm support plate; 102. Forearm support; 1021. Forearm strut; 1022. Handle; 103. Artificial pneumatic muscles; 104. Support components. Detailed Implementation

[0052] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the present invention.

[0053] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0054] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0055] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0056] Firstly, this embodiment provides a soft contact force sensor. Figure 1 This is a schematic diagram of the structure of a soft contact force sensor provided in this embodiment. Figure 2 This is a partial structural cross-sectional view of a soft contact force sensor provided in this embodiment.

[0057] like Figure 1 and Figure 2As shown, the soft contact force sensor includes: a base shell 1, a soft airbag 2, a first pressure sensor 6, at least one second pressure sensor 4, and a controller 7. The base shell 1 is used for mounting on an exoskeleton robot. The base shell 1 includes a receiving groove 11. The soft airbag 2 is housed in the receiving groove 11. The upper part of the soft airbag 2 protrudes from the top of the receiving groove 11 for contact with the wearer. The soft airbag 2 is provided with a water inlet 22. The signal input terminal of the first pressure sensor 6 is sealed to the water inlet 22 via a connector 3. The second pressure sensor 4 is disposed between the side wall of the receiving groove 11 and the soft airbag 2. The controller 7 is connected to the signal output terminals of the first pressure sensor 6 and the second pressure sensor 4, respectively. The controller 7 can acquire the contact force value based on the pressure signals from the first pressure sensor 6 and the second pressure sensor 4 and send the contact force value to a host computer.

[0058] In some examples, see Figure 1 and Figure 2 The base shell 1 is made of polylactic acid (PLA). Polylactic acid, also known as polylactide, is a polyester polymer obtained by polymerizing lactic acid as the main raw material. It is a novel biodegradable material made from starch derived from renewable plant resources (such as corn), is environmentally friendly, and possesses good mechanical properties. However, it should be noted that in other embodiments, the base shell 1 can also be made of other materials; this embodiment does not impose excessive restrictions on this.

[0059] The base shell 1 of this embodiment has low density and high rigidity characteristics, providing the necessary rigid support for the soft airbag and facilitating the assembly of various parts of the soft contact force sensor.

[0060] In some examples, see Figure 1 and Figure 2 The base shell 1 is manufactured by 3D printing in a single piece. 3D printing offers advantages such as fast manufacturing and low cost. However, it should be noted that in other embodiments, the base shell 1 can also be manufactured using other processes, such as injection molding.

[0061] In some examples, see Figure 1 and Figure 2 The soft airbag 2 is made of silicone rubber. Silicone rubber has excellent medical properties; it is colorless, non-toxic, heat-resistant, oxidation-resistant, and flexible, meeting the medical needs of patients.

[0062] In some examples, such as Figure 1 and Figure 2 As shown, the soft airbag 2 is manufactured through a single injection molding process. This design ensures the airtightness of the soft airbag 2.

[0063] In some examples, such asFigure 1 and Figure 2 As shown, the first pressure sensor 6 is a gas pressure sensor used to detect changes in gas pressure within the soft airbag 2. With this configuration, when an external force is applied to the contact surface of the soft airbag 2, the volume of the soft airbag 2 will change, causing a corresponding change in the gas pressure within the air chamber of the soft airbag 2. The first pressure sensor 6 can obtain this change value, which can be used by the controller 7 to estimate the positive pressure component of the contact force.

[0064] In some examples, see Figure 1 and Figure 2 The controller 7 includes a microcontroller. A microcontroller is an integrated circuit chip that uses very large-scale integrated circuit technology to integrate a central processing unit (CPU) with data processing capabilities, random access memory (RAM), read-only memory (ROM), various I / O ports and interrupt systems, timers / counters, and other functions (and may also include display driver circuits, pulse width modulation circuits, analog multiplexers, A / D converters, etc.) onto a single silicon chip, forming a small but complete microcomputer system. It is equivalent to a miniature computer, possessing advantages such as small size, light weight, low cost, and comprehensive functionality. In this embodiment, the microcontroller can read the readings of the first pressure sensor 6 and the second pressure sensor 4, and use relevant mathematical models to estimate the contact force.

[0065] In some examples, see Figure 1 and Figure 2 The controller 7 transmits the contact force information to a remote host computer via serial communication or Bluetooth communication. However, it is understood that in other embodiments, the controller 7 and the host computer may use other communication methods, and this embodiment does not impose any restrictions on this.

[0066] The soft contact force sensor provided in this embodiment is mounted on the exoskeleton robot via the base shell 1. The upper part of the soft airbag 2 protrudes from the top of the receiving groove 11 for contact with the wearer. When the wearer contacts the soft airbag 2, the contact force compresses the volume of the soft airbag 2, causing a change in its internal air pressure. The first pressure sensor 6 is connected to the soft airbag 2 and can acquire the positive pressure, while the second pressure sensor 4 is disposed between the side wall of the receiving groove 11 and the soft airbag 2 and can acquire the tangential force. The controller 7 can then calculate the contact force value based on the positive pressure and tangential force and send it to the host computer. The soft contact force sensor provided in this embodiment can detect the positive pressure value through the soft airbag 2 and the first pressure sensor 6, and detect the tangential force value through the second pressure sensor 4, realizing two-dimensional force sensing function while ensuring the comfort of the wearer.

[0067] In some embodiments, such as Figure 1 , Figure 2As shown, a first through hole 13 is provided on the side wall of the receiving groove 11. A protrusion 21 is provided on the surface of the soft airbag 2. The protrusion 21 extends into the first through hole 13. The sprue 22 passes through the end face of the protrusion 21 into the soft airbag 2.

[0068] In some examples, such as Figure 1 , Figure 2 As shown, the protrusion 21 is integrally formed with the soft airbag 2. This design ensures the airtightness of the soft airbag 2.

[0069] In some examples, such as Figure 1 , Figure 2 As shown, the receiving groove 11 is a rectangular groove, and the shape of the soft airbag 2 is adapted to the shape of the receiving groove 11. This arrangement makes it easier for the first pressure sensor 6 to detect changes in gas pressure in the soft airbag 2 when the soft airbag 2 is deformed under force.

[0070] In this embodiment, a protrusion 21 is provided on the surface of the soft airbag 2, and the water inlet 22 is provided on the protrusion 21. This can prevent the water inlet 22 of the soft airbag 2 from breaking during use and extend its service life. In addition, the protrusion 21 of this embodiment extends into the first through hole 13, which facilitates the connection of the first pressure sensor 6 and helps to ensure the airtightness of the connection between the soft airbag 2 and the first pressure sensor 6.

[0071] In some embodiments, such as Figure 3 and Figure 4 As shown, connector 3 includes a large-diameter section 31 and a small-diameter section 33 connected in sequence. A retaining flange 32 is provided at the connection between the large-diameter section 31 and the small-diameter section 33. Figure 2 As shown, the large-diameter section 31 is inserted into the first through hole 13 and surrounds the protrusion 21. The inner wall of the large-diameter section 31 is sealed to the side wall of the protrusion 21. The outer diameter of the retaining flange 32 is larger than the diameter of the first through hole 13. The retaining flange 32 fits against the outer wall of the receiving groove 11. The small-diameter section 33 is connected to the signal input terminal of the first pressure sensor 6 via a flexible hose 5.

[0072] In some examples, such as Figure 2 As shown, the small-diameter section 33 of connector 3 is inserted into hose 5. This arrangement facilitates assembly and ensures airtightness at the connection between connector 3 and hose 5.

[0073] In some examples, see Figure 2Connector 3 is made of engineering plastics. Engineering plastics can be divided into two categories: general-purpose engineering plastics and special-purpose engineering plastics. The former mainly includes five major types of general-purpose engineering plastics: polyamide, polycarbonate, polyoxymethylene, modified polyphenylene ether, and thermoplastic polyester. The latter mainly refers to engineering plastics with heat resistance up to 150℃ or higher, including polyimide, polyphenylene sulfide, polysulfones, aromatic polyamides, polyarylates, polyphenylene esters, polyaryletherketones, liquid crystal polymers, and fluoropolymers. Compared with general-purpose plastics, engineering plastics have excellent heat and cold resistance, excellent mechanical properties over a wide temperature range, are suitable for use as structural materials, and have good corrosion resistance, are less affected by the environment, and have good durability, making them suitable materials for connectors.

[0074] In this embodiment, the flexible hose 5 provides conductivity between the soft airbag 2 and the first pressure sensor 6. The connector 3 can fill the gap between the first through hole 13 on the side of the base housing 1 and the water inlet 22 of the soft airbag 2, improving the airtightness of the soft contact force sensor.

[0075] In some embodiments, such as Figure 1 As shown, the base housing 1 also includes at least one second through hole 14. The second pressure sensor 4 includes a pressure-sensitive resistor 41 and a signal amplifier 42. The pressure-sensitive resistor 41 is disposed between the side wall of the receiving groove 11 and the soft airbag 2. The signal output terminal of the pressure-sensitive resistor 41 is connected to a signal line. The signal line extends through the second through hole 14 to the outside of the receiving groove 11 and is connected to the input terminal of the signal amplifier 42. The output terminal of the signal amplifier 42 is connected to the controller 7.

[0076] In some examples, the base shell 1 also includes two second through holes 14. There are two second pressure sensors 4, with their pressure-sensitive resistors 41 located on the front and rear sides of the soft airbag 2, respectively. When the contact force has components in both the front and rear directions, the side of the soft airbag 2 transmits this pressure to the base shell 1, which is then detected by the pressure-sensitive resistors 41, achieving multi-dimensional contact force sensing. It is understood that in other embodiments, there may be more than two second pressure sensors 4, arranged on different sides of the soft airbag 2, to sense force components in more directions.

[0077] This embodiment utilizes a flexible pressure-sensitive resistor 41 in conjunction with a signal amplifier 42 to capture the pressure transmitted from the side of the soft airbag 2 to the base shell 1, thereby realizing a two-dimensional force sensing function and improving the comfort of the wearer.

[0078] In some embodiments, such as Figure 2 As shown, the base shell 1 also includes a base plate 12. A receiving groove 11 is disposed on the base plate 12. The base plate 12 is provided with a plurality of threaded holes 15.

[0079] In some examples, such as Figure 2As shown, the receiving groove 11 and the base plate 12 are integrally formed. They are manufactured using 3D printing or injection molding processes. This design facilitates processing.

[0080] In this embodiment, the base plate 12 of the base shell 1 is provided with multiple threaded holes 15, so that the base shell 1 can be installed on the physical human-machine interface of the exoskeleton robot by bolts, which facilitates installation and disassembly.

[0081] The structure of the soft contact force sensor has been described above. Next, a fabrication method will be introduced.

[0082] Secondly, this embodiment also provides a preparation method for fabricating the soft contact force sensor in the above embodiment. Figure 6 This is a flowchart of a preparation method provided in this embodiment.

[0083] like Figure 6 As shown, the preparation method of this embodiment includes the following steps:

[0084] S1. Determine the dimensions of the base shell 1 and the soft airbag 2 based on the dimensions of the physical human-machine interface on the exoskeleton robot.

[0085] Specifically, based on the size requirements of the physical human-machine interface of the exoskeleton robot, the overall size of the soft contact force sensor is determined. In order to improve the sensitivity of the soft airbag 2, the wall thickness of the soft airbag 2 should not exceed 5mm.

[0086] S2. Prepare airbag mold 9 according to the dimensions of soft airbag 2.

[0087] Specifically, since the soft airbag 2 has a certain wall thickness, the airbag mold 9 is designed as a detachable assembly structure, and the mold is processed using 3D printing technology.

[0088] S3. The soft airbag 2 is produced by injection molding using the airbag mold 9.

[0089] Specifically, after the soft airbag 2 is produced by injection molding, the sprue 22 of the soft airbag 2 needs to be trimmed in order to facilitate the installation of the connector 3.

[0090] S4. Connector 3 is manufactured using 3D printing.

[0091] Specifically, to improve airtightness, the printing density of connector 3 can be 100%.

[0092] S5. Fabricate the base shell 1 and install the soft airbag 2 into the base shell 1.

[0093] Specifically, the base shell 1 is made of PLA material, which has low density and high rigidity characteristics, providing necessary rigid support for the soft airbag 2 and facilitating the assembly of various parts of the soft contact force sensor. The base shell 1 can be manufactured using 3D printing, and during the manufacturing process, a first through hole 13 is opened on one side for mounting the sprue 22 and connector 3 of the soft airbag 2. Two threaded holes 15 are opened on the base plate 12 for mounting the soft contact force sensor to the physical human-machine interface of the exoskeleton robot; two second through holes 14 are opened at the bottom of the receiving groove 11 for routing the piezoresistor 41.

[0094] S6. Assemble the soft airbag 2, connector 3 and other components to form a soft contact force sensor.

[0095] Specifically, such as Figure 1 As shown, other components include hose 5, first pressure sensor 6, two pressure-sensitive resistors 41, two signal amplifiers 42, and controller 7. Their connection relationships are shown in [reference needed]. Figure 1 .

[0096] The fabrication method provided in this embodiment can produce the aforementioned soft contact force sensor, thus improving the comfort of wearers using exoskeleton robots. The soft contact force sensor fabricated using this method can perfectly fit the exoskeleton robot and is suitable for mass production, which helps reduce the manufacturing cost of the soft contact force sensor.

[0097] In some embodiments, such as Figure 8 , Figure 9 As shown, the airbag mold 9 includes: a mold base 94, a front mold 93 and a rear mold 92, a mold core 95, and an end cap 91. The mold base 94 has a slot. The front mold 93 and the rear mold 92 interlock and are inserted into the slot. A mold cavity 96 is formed between the front mold 93 and the rear mold 92. The mold cavity 96 has an injection port. The mold core 95 is located in the mold cavity 96. A gap is formed between the surface of the mold core 95 and the inner wall of the mold cavity 96. The gap is adapted to the wall thickness of the soft airbag 2. The melting point of the mold core 95 is lower than the melting point of the soft airbag 2. The end cap 91 is fastened to the end of the front mold 93 and the rear mold 92 furthest from the mold base 94. Except for the mold core 95, all other structures are obtained using 3D printing technology, and their material is PLA.

[0098] In some examples, such as Figure 8 , Figure 9 As shown, the end cap 91 is a split design, including a front end cap 911 and a rear end cap 912. This design facilitates demolding.

[0099] like Figure 7 As shown, S3. The soft airbag 2 is manufactured using the airbag mold 9 through an injection molding process, including:

[0100] S31. Prepare silica gel stock solution and coagulant, stir and let stand for the first preset time in a laboratory environment.

[0101] Specifically, the ratio of silica gel stock solution to coagulant is 1:1, and after stirring, it should be left to stand for at least 15 minutes in a laboratory environment (room temperature 22-25℃).

[0102] S32. Use a vacuum pump to evacuate and remove air bubbles from the mold cavity 96.

[0103] Specifically, degassing the mold cavity 96 can prevent air bubbles from forming on the wall of the soft airbag 2, and allow the mixture of silicone stock solution and coagulant to fill the mold cavity 96.

[0104] S33. Inject the prepared silicone stock solution and coagulant into the mold cavity 96.

[0105] Specifically, such as Figure 8 As shown, the injection port of the airbag mold 9 is located at the sprue 22 of the soft airbag 2.

[0106] S34. After waiting for the second preset time in a laboratory environment, disassemble the mold to obtain the soft airbag 2.

[0107] Specifically, after waiting for 20 to 30 minutes in a laboratory environment (room temperature 22 to 25°C), the mold was removed to obtain the soft airbag 2.

[0108] S35. After heating the soft airbag 2 until the mold core 95 melts, remove the mold core 95 from the soft airbag 2.

[0109] Specifically, the soft airbag 2 obtained by the above method contains a mold core 95 inside. Therefore, heating the soft airbag 2 to a certain temperature (e.g., 75°C) can melt the mold core 95 into a liquid. However, this temperature is lower than the melting temperature of the soft airbag 2 (generally 250°C to 300°C), so it will not damage the internal structure of the soft airbag 2.

[0110] This embodiment utilizes the airbag mold 9 to manufacture the soft airbag 2, which is highly efficient, can be repeatedly produced, and is suitable for mass production.

[0111] In some embodiments, see Figure 9 The mold core 95 is made of paraffin wax and is produced by injection molding.

[0112] In some examples, such as Figure 9 As shown, the mold core 95 includes a main body 951, a sprue 952, and a protrusion 953 connected in sequence. During injection molding, the main body 951 is used to form the air cavity of the soft airbag 2, the sprue 952 is used to form the sprue 22 of the soft airbag 2, and the protrusion 93 extends out of the outside of the airbag mold 9 to facilitate the support and fixation of the mold core 95, so that the mold core 95 can be suspended in the mold cavity 96.

[0113] In some examples, the mold core 95 is like... Figure 10 As shown, two core molds 97 interlock to form a cavity for making a core mold 95. The cavity includes a first chamber 971, a second chamber 972, and a third chamber 973 connected in sequence. The first chamber 971 is used to form the main body 951 of the core mold 95, the second chamber 972 is used to form the sprue 952 of the core mold 95, and the third chamber 973 is used to form the protrusion 953 of the core mold 95. The third chamber 973 also serves as the injection port of the core mold 95.

[0114] In this embodiment, to improve the airtightness of the air chamber of the soft airbag 2, paraffin material is used as the inner wall mold (i.e., mold core 95). The different melting points of paraffin material and silicone rubber material are used to achieve demolding and molding, and a sprue 22 is left for connecting the hose 5 and the connector 3.

[0115] Thirdly, this embodiment also provides an exoskeleton robot. Figure 11 This is a schematic diagram of the structure of an exoskeleton robot provided in this embodiment.

[0116] like Figure 11 As shown, the exoskeleton robot of this embodiment includes: an exoskeleton robot body 10 and at least one of the aforementioned soft contact force sensors. The exoskeleton robot body 10 includes at least one physical human-machine interface 8. Each soft contact force sensor is disposed on a physical human-machine interface 8 and is used to contact the wearer to obtain the contact force between the wearer and the physical human-machine interface when the wearer moves.

[0117] In some examples, such as Figure 11 As shown, the exoskeleton robot body 10 includes two physical human-machine interaction interfaces 8, namely the upper physical human-machine interaction interface 81 and the lower physical human-machine interaction interface 82.

[0118] The exoskeleton robot in this embodiment is an upper limb exoskeleton robot, mainly used to provide assistance to the wearer's elbow joint, helping the wearer to achieve elbow flexion / extension movements. However, it is understood that soft contact force sensors can also be used in lower limb exoskeleton robots and other exoskeleton robots for any other part of the body.

[0119] The exoskeleton robot provided in this embodiment is equipped with the aforementioned soft contact force sensor, which improves the comfort of the wearer and makes it more acceptable to the wearer.

[0120] In some embodiments, such as Figure 11As shown, the exoskeleton robot body 10 includes: an upper arm support 101, a forearm support 102, a support member 104, artificial pneumatic muscles 103, and a pair of physical human-machine interfaces 8 (an upper physical human-machine interface 81 and a lower physical human-machine interface 82). The upper arm support 101 includes an arm support plate 1012. One end of the forearm support 102 is hinged to the upper arm support 101, and the other end has a handle 1022. The support member 104 is telescopically connected between the upper arm support 101 and the forearm support 102. The artificial pneumatic muscles 103 are telescopically connected between the upper arm support 101 and the forearm support 102. The pair of physical human-machine interfaces 8 are located above and below the forearm support 102, respectively.

[0121] In some examples, such as Figure 11 As shown, the support member 104 is a support-type gas spring.

[0122] In some examples, such as Figure 11 As shown, the upper arm support 101 includes a pair of parallel upper arm struts 1011, and an arc-shaped arm support plate 1012 connected between the pair of upper arm struts 1011. The forearm support 102 includes a pair of parallel forearm struts 1021, and a handle 1022 connected between the pair of forearm struts 1021.

[0123] When the wearer wears the exoskeleton robot of this embodiment, the wearer's hands grip the handle 1022, and their forearm is positioned between a pair of forearm struts 1021 and between the upper physical human-machine interface 81 and the lower physical human-machine interface 82. The upper arm is positioned between a pair of upper arm struts 1011 and above the arm support plate 1012. When the wearer performs elbow flexion, their forearm will inevitably contact the upper physical human-machine interface 81, generating a contact force F; and when the wearer performs elbow extension, their forearm will inevitably contact the lower physical human-machine interface 82, also generating a contact force F.

[0124] like Figure 5 As shown, under the action of contact force F, the volume of the soft airbag 2 will be compressed, where 23 is the outline of the soft airbag before the force is applied, and 24 is the outline of the soft airbag after the force is applied. Figure 5 It can be seen that the contact force F has a normal force component F. c and tangential force component F t Because the soft airbag 2 has good airtightness, its internal air pressure p will change significantly, and the first pressure sensor 6 can obtain the positive pressure component F. c Simultaneously, the tangential force component F t The signal is transmitted through the sidewall of the soft airbag 2 to the surface of the pressure-sensitive resistor 41, causing a change in the reading of the signal amplifier 42.

[0125] The controller is calculated as follows:

[0126] According to the beam-plate deformation principle in mechanics of materials, the relationship between the current air pressure and the normal pressure of the soft airbag 2 is expressed as follows:

[0127]

[0128] Where k is a positive constant, representing the linearity coefficient of the soft contact force sensor, p0 is the initial air pressure of the soft airbag 2, p is the current air pressure of the soft airbag 2, and E s V represents the elastic modulus of the silicone rubber material, V represents the volume of the soft airbag 2, e represents the cross-sectional width of the soft airbag 2, l represents the cross-sectional length of the soft airbag 2, and b is a constant coefficient term whose value is related to the surface thickness of the soft airbag 2.

[0129] The relationship between the reading of varistor 41 and the tangential force is expressed as follows:

[0130] F t =K[(U1-U 10 )-(U2-U 20 (2)

[0131] like Figure 5 As shown, according to the inequality of the three sides of a right triangle, the magnitude of the contact force F is...

[0132]

[0133] According to geometric relationships, the angle between the direction of the contact force and the mounting plane of the soft contact force sensor is...

[0134] θ = arctan(F) c / F t (4)

[0135] Where K is the fitting coefficient, and since the varistor 41 has strong linearity within its rated range, K is a constant. U1 and U2 represent the current readings of the two varistor 41s, respectively. 10 U 20 These represent the initial readings of the two varistor 41, one before and one after.

[0136] The exoskeleton robot in this embodiment includes a soft contact force sensor. The controller 7 of the soft contact force sensor uses the microcontroller serial communication principle to send the readings of the soft contact force sensor to the host computer. Assuming that analog port 1 of the controller is connected to the first pressure sensor 6, and analog ports 2 and 3 are respectively connected to the signal amplifiers 42 of two pressure-sensitive resistors 41, the pseudocode of the algorithm is as follows:

[0137] Define global variables;

[0138] Configure communication frequency;

[0139] Define an analog port;

[0140] While (analog port has data to be read) {

[0141] Read the current data from analog port 1 and assign the current reading to variable x;

[0142] Read the current data from analog port 2 and assign the current reading to variable y;

[0143] Read the current data from analog port 3 and assign the current reading to variable z;

[0144] According to the instruction manual of the first pressure sensor, the variable x is converted into the actual air pressure value and reassigned to the variable x;

[0145] According to formula (1), the variable x is converted into a positive pressure value, and this value is assigned to the variable F. c ;

[0146] According to formula (2), variables y and z are converted into tangential force values, and these values ​​are then assigned to variable F. t ;

[0147] variable F c and variable F t Send to the host computer via serial communication function;

[0148] Delay 10ms;

[0149] }

[0150] Burn in the program to complete the calibration and testing.

[0151] It will be readily understood by those skilled in the art that the aforementioned advantageous methods can be freely combined and superimposed without conflict.

[0152] The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application. The above are merely preferred embodiments of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of this application, and these improvements and modifications should also be considered within the protection scope of this application.

Claims

1. A soft contact force sensor, characterized in that, include: A base shell for mounting on an exoskeleton robot; the base shell includes a receiving groove; A soft airbag is housed in the receiving groove; The upper part of the soft airbag protrudes from the top of the receiving groove for contact with the wearer; the soft airbag is provided with a water inlet. A first pressure sensor, the signal input terminal of which is sealed to the water inlet via a connector; At least one second pressure sensor is disposed between the side wall of the receiving groove and the soft airbag; The controller is connected to the signal output terminal of the first pressure sensor and the signal output terminal of the second pressure sensor, respectively. The controller can obtain the contact force value based on the pressure signals from the first pressure sensor and the second pressure sensor, and send the contact force value to the host computer.

2. The soft contact force sensor according to claim 1, characterized in that, The side wall of the receiving groove is provided with a first through hole; the surface of the soft airbag includes a protrusion; the protrusion extends into the first through hole; the water inlet extends from the end face of the protrusion into the soft airbag.

3. The soft contact force sensor according to claim 2, characterized in that, The connector includes a large-diameter section and a small-diameter section connected in sequence; a retaining edge is provided at the connection between the large-diameter section and the small-diameter section; The large-diameter section is inserted into the first through hole and surrounds the protrusion inside; the inner wall of the large-diameter section and the side wall of the protrusion are sealed together. The outer diameter of the retaining edge is larger than the diameter of the first through hole; the retaining edge is attached to the outer wall of the receiving groove; The smaller diameter section is connected to the signal input terminal of the first pressure sensor via a flexible hose.

4. The soft contact force sensor according to claim 1, characterized in that, The substrate housing also includes at least one second through hole; the second pressure sensor includes a pressure-sensitive resistor and a signal amplifier; The piezoresistor is disposed between the side wall of the receiving groove and the soft airbag; the signal output terminal of the piezoresistor is connected to a signal line; the signal line extends out of the receiving groove through the second through hole and is connected to the input terminal of the signal amplifier; the output terminal of the signal amplifier is connected to the controller.

5. The soft contact force sensor according to claim 1, characterized in that, The base shell also includes a bottom plate; the receiving groove is disposed on the bottom plate; the bottom plate is provided with multiple threaded holes.

6. A method for fabricating a soft contact force sensor as described in any one of claims 1 to 5, characterized in that, Includes the following steps: The dimensions of the base shell and the soft airbag are determined based on the dimensions of the physical human-computer interaction interface on the exoskeleton robot. Prepare an airbag mold according to the dimensions of the soft airbag; A soft airbag is manufactured using the aforementioned airbag mold through an injection molding process; Connectors are manufactured using 3D printing; Fabricate a base shell and install the soft airbag in the base shell; The soft airbag, the connector, and other components are assembled to form a soft contact force sensor.

7. The preparation method according to claim 6, characterized in that, The airbag mold includes: a mold base, a front mold and a rear mold, a mold core, and an end cap; the mold base has a slot; the front mold and the rear mold are interlocked and inserted into the slot; a mold cavity is formed between the front mold and the rear mold; the mold cavity has an injection port; the mold core is located in the mold cavity; a gap is formed between the surface of the mold core and the inner wall of the mold cavity; the gap is adapted to the wall thickness of the soft airbag; the melting point of the mold core is lower than the melting point of the soft airbag; the end cap is fastened to the end of the front mold and the rear mold away from the mold base; The process of manufacturing a soft airbag using the airbag mold through injection molding includes: Prepare the silica gel stock solution and coagulant, stir, and let stand for the first preset time in a laboratory environment; A vacuum pump is used to evacuate and remove air bubbles from the mold cavity; Inject the prepared silicone stock solution and coagulant into the mold cavity; After waiting for the second preset time in a laboratory environment, the mold is disassembled to obtain the soft airbag; After heating the soft airbag until the mold core melts, the mold core is extracted from the soft airbag.

8. The preparation method according to claim 7, characterized in that, The mold core is made of paraffin wax and is manufactured by injection molding.

9. An exoskeleton robot, characterized in that, include: An exoskeleton robot body, wherein the exoskeleton robot body includes at least one physical human-machine interface; At least one soft contact force sensor as described in any one of claims 1 to 5, each of the soft contact force sensors being disposed on one of the physical human-machine interface for contacting the wearer to obtain the contact force between the wearer and the physical human-machine interface during movement.

10. The exoskeleton robot according to claim 9, characterized in that, The exoskeleton robot body includes: Upper arm support, the upper arm support including an arm support plate; A forearm support, one end of which is hinged to the upper arm support, and the other end of which is provided with a handle; A support member is telescopically connected between the upper arm support and the forearm support; An artificial pneumatic muscle is telescopically connected between the upper arm support and the forearm support. A pair of physical human-computer interaction interfaces are located above and below the forearm support, respectively.

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