A variable stiffness soft robotic arm for minimally invasive surgery and its use method

Abstract

The present invention relates to a soft robotic arm, and specifically to a variable stiffness soft robotic arm for minimally invasive surgery and a method for using the same. The variable stiffness soft robotic arm for minimally invasive surgery includes a variable stiffness support arm and a sleeve mounted on the variable stiffness support arm. The sleeve includes a bending section and a torsion section. The bending section and the torsion section are respectively wrapped with multiple wire loops and spiral wires. The bending section and the torsion section are respectively provided with at least two or more chambers distributed radially along the variable stiffness support arm and connected to a charging and discharging module. The chambers are charged and discharged with medium to achieve bending and torsion of the robotic arm. The overall variable stiffness support arm, bending section and torsion section of the present invention have the same structure. The type of bending and torsion can be changed by simply changing the wire loops or spiral wires wrapped around the outer wall. This greatly simplifies the structural design and arrangement of the robotic arm, making it convenient to combine different bending sections and torsion sections according to actual needs, and has good compliance.

Description

Technical Field

[0001] The present invention relates to a soft robotic arm, and in particular to a soft robotic arm with variable stiffness for minimally invasive surgery and a method of using the same. Background Art

[0002] The rapid development of science and technology has increased human scrutiny of machine safety, and the consideration of safety in human-computer interaction in modern mechanical design has also been greatly improved. Therefore, soft robots with good adaptability and human-computer interaction safety have quickly become a hot topic in robotics and are considered by relevant practitioners to be an important future development direction in the field of robotics.

[0003] Traditionally, robotic arms used in surgery are integrated into surgical robotic systems to assist in the smooth execution of surgical procedures. These stable, precise, and flexible robotic arms can perform operations in confined spaces beyond the reach of human hands. However, rigid robotic arms can easily damage delicate human tissue, and surgical robots are expensive. Consequently, soft robotic arms for minimally invasive surgery have garnered widespread attention.

[0004] Compact soft robotic arms can penetrate through incisions in the human body, perform endoscopic examinations similar to those performed by gastroscopy, and can also perform operations such as grasping by loading functional modules at the end. While flexibility offers numerous advantages, current soft robotic arms also suffer from insufficient rigidity, resulting in poor stability, complex internal structures that hinder the arrangement and combination of twisting and bending modules, and the need for multiple power devices for the same soft robotic arm, according to the company.

[0005] The Chinese invention patent application number CN201810935837.3, titled "A Variable-Stiffness Soft Robotic Arm Controlled by Electrorheological Fluid," states: "The variable-stiffness device is filled with electrorheological fluid. By varying the voltage, the fluid's liquid-solid-liquid transition is achieved, thereby varying the stiffness. Three air cavities are evenly distributed around the soft robotic arm body, connected to a quick connector via a sealing device to deliver gas to cause it to bend." The variable-stiffness module is controlled by voltage, while the bending is controlled by delivering gas, which makes operation inconvenient and requires multiple control devices. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a variable stiffness soft robotic arm for minimally invasive surgery, which has a variety of torsion segment and bending segment combinations, is easy to control and has a simple structure, and a method for using the same.

[0007] The content of the present invention includes a variable stiffness support arm and a sleeve mounted on the variable stiffness support arm. The sleeve includes a bending section and a torsion section. The bending section and the torsion section are respectively wrapped with multiple wire loops and spiral wires. The bending section and the torsion section are respectively provided with at least two or more chambers distributed radially along the variable stiffness support arm and connected to the charging and discharging module. The medium is charged and discharged in the chamber to realize the bending and torsion of the robotic arm.

[0008] The charging and discharging module can fill and absorb the medium in the chamber. The medium can be gas or liquid, preferably compressed air. In addition, the size of the chamber and the length of the bending section and the torsion section can be adjusted according to actual work needs to obtain the best use effect.

[0009] Furthermore, the variable stiffness support arm includes an inner tube connected to the charging and discharging module and an outer tube sleeved on the inner tube. The inner tube and the outer tube are filled with blocking particles. The blocking particles are particles with a large friction coefficient to increase stability in a tight state.

[0010] Furthermore, the chamber may be in other shapes such as circular, elliptical, rectangular, or fan-shaped, preferably a fan-shaped chamber. The chamber may be an airbag structure or a cavity structure.

[0011] Furthermore, a support bar is provided between every two chambers of the bending section or the torsion section distributed radially along the sleeve.

[0012] Furthermore, a reserved through hole is provided in the support bar along the axis direction of the sleeve, and a pipeline III is provided in the reserved through hole. One end of the pipeline III is connected to the charging and discharging module, and the other end is connected to the chamber of the other curved section.

[0013] Furthermore, there are three chambers distributed circumferentially around the central axis of the sleeve.

[0014] Furthermore, the bending section and the torsion section are separated, and the separation improves the control accuracy of torsion and bending, so that adjacent bending sections or torsion sections do not interfere with each other.

[0015] Furthermore, the wire loops are closely arranged along the curved section.

[0016] Furthermore, the helical wire is in the form of a single helix, a double helix or a multi-helix with a large inclination angle and is arranged on the outer wall of the torsion section.

[0017] A method for using a variable stiffness soft robotic arm for minimally invasive surgery comprises the following steps:

[0018] Step 1: Control the charging and discharging module to charge and discharge the medium in each chamber in the bending section separately to achieve bending deformation of the bending section. By controlling the medium pressure and the charging and discharging sequence, bending of different degrees and directions can be achieved. At the same time, control the charging and discharging module to charge and discharge the medium in each chamber in the torsional section at the same time to achieve torsional deformation of the torsional section.

[0019] Step 2: Control the charging and discharging module to fill the inner tube with medium, causing the inner tube to expand radially and squeeze the blocking particles to increase the stiffness of the variable stiffness support arm. The medium pressure in the inner tube corresponds to the different stiffness of the variable stiffness support arm.

[0020] The beneficial effect of the present invention is that the overall variable stiffness support arm, bending section and torsion section of the present invention have the same structure, and the type of bending and torsion can be changed by simply changing the wire ring or spiral wire wrapped around the outer wall, which greatly simplifies the structural design and arrangement and combination difficulty of the robot arm, facilitates the combination of different bending sections and torsion sections according to actual needs, has good compliance, and reduces manufacturing processes during production and manufacturing, and improves mold utilization.

[0021] The variable stiffness support arm of the present invention uses an inner tube, an outer tube, and is filled with blocking particles. Like the bending and torsion sections, it uses positive pressure control. Only a compressed gas device or hydraulic device is needed to achieve variable stiffness, bending, and torsion control, reducing the number of power sources and solving the problems of low stiffness and end force of current soft robotic arms.

[0022] The cavity of the present invention adopts a sector cavity, which has the characteristics of large cross-sectional area and high utilization rate of the robot arm. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural schematic diagram of the present invention.

[0024] Figure 2 It is a cross-sectional schematic diagram of the present invention.

[0025] Figure 3 This is a schematic diagram of the installation of pipeline III in the present invention.

[0026] Figure 4 This is a schematic diagram of the installation of pipelines I-III in the present invention.

[0027] Figure 5 It is a structural schematic diagram of the variable stiffness support arm in the present invention.

[0028] Figure 6 It is a structural schematic diagram of the curved section in the present invention.

[0029] Figure 7 It is a structural schematic diagram of the torsion section in the present invention.

[0030] Figure 8 It is a structural schematic diagram of pipeline II in the present invention.

[0031] Figure 9 This is a schematic diagram of the installation of pipeline II in the present invention.

[0032] Figure 10This is a schematic diagram of the installation of pipeline IV in the present invention.

[0033] Figure 11 It is a structural schematic diagram of the fixing module in the present invention.

[0034] Figure 12 It is a structural diagram of the accessory connection module in the present invention.

[0035] In the figure, 1 is an inner tube, 2 is an outer tube, 3 is a sleeve, 4 is a support bar, 5 is a blocking particle, 6 is a reserved through hole, 7 is a chamber, 8 is a pipe I, 9 is a pipe II, 901 is a branch pipe, 10 is a pipe III, 11 is a wire ring, 12 is a spiral wire, 13 is a fixing module, 1301 is a fixing body, 1302 is a mounting platform connecting bolt hole, 1303 is a fastening slider, 1304 is a fastening bolt, 1305 is a triangular slide, 1306 is a triangular slider, 14 is an accessory connecting module, 1401 is an accessory connecting body, 1402 is an accessory connecting bolt hole, 1403 is a fastening bolt hole, 1404 is a fixing chamber, 15 is a pipe IV, 16 is a torsion segment I, 17 is a bending segment I, 18 is a torsion segment II, 19 is a bending segment II, 20 is a torsion segment III. DETAILED DESCRIPTION

[0036] like Figure 1-12 As shown, the present invention includes a variable stiffness support arm and a sleeve 3 sleeved on the variable stiffness support arm, the variable stiffness support arm and the sleeve 3 are both made of soft materials, such as silicone material, the sleeve 3 includes a bending section and a torsional section, a plurality of wire loops 11 are wound around the outside of the bending section, and a spiral wire 12 is wound around the outside of the torsional section, the wire loops 11 and the spiral wire 12 are both made of tensile-resistant and non-tear materials, such as fiber, Kevlar or nylon, etc. The wire loops 11 and the spiral wire 12 can be wound around the outer wall of the sleeve 3, or can be embedded in the outer wall of the sleeve 3, the bending section and the torsional section are respectively provided with at least two or more chambers 7 distributed radially along the variable stiffness support arm and connected to the charging and discharging modules, the medium is charged and discharged into the chamber 7, so that the bending section or the torsional section expands, and while expanding, it is restricted by the wire loops 11 and the spiral wire 12, resulting in bending and torsional deformation, thereby realizing the bending and torsional deformation of the robotic arm.

[0037] A plurality of wire loops 11 are wound around the outside of the bending section, which limit the radial expansion of the chamber 7 when the medium is filled, so that the bending section bends in the opposite direction toward the chamber filled with the medium. A spiral wire 12 is wound around the outside of the torsion section, which converts the torsion section, which originally expands and deforms in the axial and radial directions at the same time, into torsional forces that deform obliquely along the helical angle direction of the spiral wire 12, and finally causes the torsion section to be torsionally deformed.

[0038] like Figure 5As shown, in order to improve the stiffness of the robotic arm after deformation, the variable stiffness support arm includes an inner tube 1 connected to the charging and discharging module and an outer tube 2 mounted on the inner tube 1. Blocking particles 5 are filled between the inner tube 1 and the outer tube 2, wherein the blocking particles are preferably ores, crystals or various granular materials with a large friction coefficient with a diameter of less than 1 mm. The blocking particles 5 are filled at 100%-120% of the volume of the cavity between the inner tube 1 and the outer tube 2. When the inner tube 1 is filled with the medium, the medium is continued to be filled. The inner tube 1 expands under the influence of the medium pressure. The expanded inner tube 1 squeezes the blocking particles 5. Under the action of static friction, the blocking particles 5 change from a loose state to a tight state, thereby presenting different stiffness. The greater the pressure of the medium, the higher the stiffness.

[0039] like Figure 2 As shown, the chamber 7 is a fan-shaped chamber. The fan-shaped setting first has the effect of large cross-sectional area and high space utilization, while reducing the material of the robotic arm, which is more conducive to lightweight design. Secondly, the fan-shaped setting makes the cavity surface area close to the wire loop 11 or the spiral wire 12 side larger, so that the expansion area of the outer wall of the sleeve 3 of the corresponding chamber 7 after being filled with the medium is larger, thereby converting the deformation into torsional or bending deformation into a larger amount.

[0040] The chamber 7 can be a balloon-like airbag structure or a cavity structure located between the sleeve 3 and the outer tube 2. In order to improve the integrity of the robotic arm, in this embodiment, it is preferably as follows Figure 2 The cavity structure shown in the figure has a support bar 4 between every two cavities 7 of the radial distribution of the bending section or the torsion section along the sleeve 3. The two side surfaces of the variable stiffness support arm 4 are the side walls of the two adjacent cavities. This cavity structure improves the connection strength of the robot arm and the integrity of the sleeve and the variable stiffness support arm. When the stiffness of the variable stiffness support arm changes, it is transferred to the sleeve 3 by the support bar 4, thereby causing the stiffness of the entire robot arm to change synchronously. At the same time, the number of variable stiffness support arms 4 is consistent with the number of cavities 7 with the same cross-section.

[0041] Of course, when the chamber 7 is an airbag structure, a variable stiffness support arm 4 can also be set. The chamber 7 of the airbag structure is set between multiple variable stiffness support arms 4, which can ensure that when the bending section is bent and deformed, after the chamber 7 of the airbag structure at different positions is filled with medium, only the fan area on the sleeve 3 corresponding to the chamber 7 will bend and deform, thereby improving the accuracy of controlling the bending deformation direction.

[0042] A reserved through hole 6 is provided in the support bar 4 along the axial direction of the sleeve 3. The provision of the reserved through hole 6 can first be provided with a pipe III10. One end of the pipe III10 is connected to the charging and discharging module, and the other end is connected to the chamber 7 of another curved section. In this way, the chamber 7 in the second curved section away from the charging and discharging module can be connected through the pipe III10. In this case, the chambers 7 at the cross section in the curved section are staggered. In addition, the provision of the reserved through hole 6 reduces the weight of the support bar 4, further reducing the weight of the robotic arm.

[0043] There are three chambers 7 distributed in a circle around the central axis of the sleeve 3. The design of three chambers 7 simplifies the layout design of subsequent pipelines and improves the accuracy of controlling the bending deformation direction.

[0044] like Figure 1 As shown, the bending segment and the torsion segment are separated and arranged, and the separation setting can prevent the deformation between adjacent bending segments and torsion segments from interfering with each other, thereby improving the accuracy of the torsion and bending deformation control of the robotic arm.

[0045] like Figure 6 As shown, the wire loops 11 can be distributed at equal intervals. In this embodiment, the wire loops 11 are closely arranged along the bending section, similar to a bellows structure. Multiple wire loops 11 are closely connected to each other, limiting the radial expansion of the bending section outward by the medium pressure of the cavity 7 as much as possible, and at the same time can play a limiting and protective role.

[0046] like Figure 7 As shown, the spiral wire 12 is a single helix, a double helix or a multi-helix with a large inclination angle and is arranged on the outer wall of the torsion section. The spiral wire 12 is arranged at a large inclination angle to avoid excessive torsional deformation due to expansion of the torsion section, and more accurately control the torsional deformation amount of the torsion section. At the same time, the spiral wire 12 can be a single helix, a double helix or a multi-helix, which also accurately controls the torsional deformation amount of the torsion section. In this embodiment, the spiral wire 12 is preferably a double helix.

[0047] A method for using a variable stiffness soft robotic arm for minimally invasive surgery comprises the following steps:

[0048] Step 1: Control the charging and discharging module to charge and discharge the medium in each chamber 7 in the bending section separately to achieve bending deformation of the bending section. By controlling the medium pressure and the charging and discharging sequence, bending of different degrees and directions can be achieved. At the same time, control the charging and discharging module to charge and discharge the medium in each chamber 7 in the torsional section at the same time to achieve torsional deformation of the torsional section.

[0049] Step 2: Control the charging and discharging module to fill the inner tube 1 with medium, causing the inner tube 1 to expand radially and squeeze the blocking particles 5 to increase the stiffness of the variable stiffness support arm. The medium pressure in the inner tube 1 corresponds to the different stiffness of the variable stiffness support arm.

[0050] The head end and the tail end of the soft robotic arm are respectively provided with a fixing module 13 and an accessory connection module 14.

[0051] The fixing module 13 includes a fixing body 1301 and a fastening slider 1303 which are screwed together by a fastening screw 1304. The fixing body 1301 and the fastening slider 1303 are correspondingly provided with a triangular slide groove 1305 and a triangular slider 1306 for clamping the sleeve 3. During installation, the sleeve 3 is installed between the triangular slide groove 1305 and the triangular slider 1306, and is tightened and locked by the fastening screw 1304. A mounting platform connecting bolt hole 1302 is extended upward on the fixing body 1301 for fixing to the mounting platform. Sufficient space is reserved above the extended part for placing pipelines and charging and discharging modules.

[0052] The accessory connection module 14 includes two accessory connection bodies 1401 that are screwed together by fastening bolt holes 1403. The accessory connection bodies 1401 are combined into a cylindrical shape. A fixing cavity 1404 for installing the sleeve 3 is provided in the cylinder. The bending section or torsion section at the end is provided with a fixing protrusion corresponding to the fixing cavity to ensure that the connection is stable and will not be detached after mating. An accessory connection bolt hole 1402 is provided at one end of the accessory connection body 1401. The accessory connection bolt hole 1402 can be connected to functional accessories such as cameras and clamps according to actual needs to achieve functional expansion.

[0053] Since the filling and discharging media of multiple chambers 7 in the curved section need to be controlled individually, the control methods are as follows:

[0054] like Figure 4 As shown, the charging and discharging medium of the chamber 7 in the curved section is connected to the charging and discharging module through the pipe I8. In this connection mode, one end of the pipe I8 is directly connected to the chamber 7, and the other end passes through the chamber 7 of all the curved sections or torsion sections close to the fixed module 13 and is connected to the charging and discharging module. When the chamber 7 is a cavity structure, multiple pipes I8 can be set in each cavity 7 at the same time. This connection mode can connect multiple curved sections. In this embodiment, three pipes I8 can be set in one chamber. Therefore, this connection mode can connect three curved sections.

[0055] like Figure 3 and Figure 4 As shown, the charging and discharging medium of the chamber 7 in the curved section is connected to the charging and discharging module via a pipe III 10. In this connection mode, one end of the pipe III 10 is connected to the chamber 7 of one curved section, and the other end is connected to the charging and discharging module through the reserved through-holes 6 of all the curved sections or torsional sections close to the fixed module 13. At this time, the chamber 7 of the curved section is staggered with the chambers 7 of other curved sections or torsional sections between the curved section and the fixed module 13.

[0056] like Figure 10As shown, the charging and discharging medium of the chamber 7 in the curved section can also be connected to the charging and discharging module through the pipe IV15. Each chamber 7 in the curved section is provided with a pipe IV15 running through the sleeve 3. The other ends of multiple pipes IV15 are connected to the charging and discharging module. Due to this connection method, part of the pipe will be exposed to the outside of the robotic arm, and it is preferably arranged on the curved section close to the fixed module 13.

[0057] The filling and discharging of the multiple chambers 7 in the torsion section need to be controlled synchronously. The control methods are as follows:

[0058] like Figure 8 and Figure 9 As shown, the charging and discharging medium of the chamber 7 in the torsional section is connected to the charging and discharging module through the pipe II9. The pipe II9 is arranged in the inner tube 1. The end face of the pipe II9 is provided with a branch pipe 901 corresponding to multiple chambers 7. The branch pipe 901 passes through the inner tube 1, the blocking particles 5 and the outer tube 2 and extends into the chamber 7. The medium flows to the branch pipe 901 through the pipe II9, and the multiple chambers 7 in the torsional section are charged and discharged at the same time. Multiple groups of pipes II9 can be set in the inner tube 1, corresponding to multiple groups of torsional sections.

[0059] Since the filling and discharging of the multiple chambers 7 in the torsion section need to be carried out synchronously, the control method can also adopt any of the three charging and discharging methods mentioned above for the bending section, and multiple pipes I8, pipes III10 and pipes IV15 can be filled and discharged with media at the same time.

[0060] Due to the structure of the robot arm and the various ways of charging and discharging the medium, the arrangement combination and number of the torsion segment and the bending segment can be adjusted according to actual needs, such as Figure 1 As shown, from the fixing module 13 to the accessory connection module 14, a torsion section I 16, a bending section I 17, a torsion section II 18, a bending section II 19 and a torsion section III 20 are sequentially arranged. In this embodiment, the torsion sections I 16, II 18 and III 20 can all use the pipe II 9 to charge and discharge the medium, while the bending sections I 17 and II 19 use the pipe I 8 and the pipe III 10 respectively. At this time, the chamber 7 in the bending section II 19 and the chambers 7 in the torsion sections I 16, I 17 and II 18 are staggered, that is, the pipe III 10 connected to the bending section II 19 is arranged in the reserved through hole 6 in the torsion sections I 16, I 17 and II 18. This structure best retains the area of the inner cavity 7 of the torsion sections I 16, I 17 and II 18, and there is no external pipe connection. The control of the charging and discharging module is simple, the control accuracy is high, and the effect is good.

Claims

1. A variable stiffness soft robotic arm for minimally invasive surgery, characterized by: The invention comprises a variable stiffness support arm and a sleeve (3) sleeved on the variable stiffness support arm, wherein the sleeve (3) comprises a bending section and a torsion section, wherein a plurality of wire loops (11) and spiral wires (12) are respectively wound around the outside of the bending section and the torsion section, and wherein at least two or more chambers (7) connected to the charging and discharging modules and distributed along the radial direction of the variable stiffness support arm are respectively provided in the bending section and the torsion section, wherein the chambers (7) are charged and discharged with a medium to realize the bending and torsion of the robot arm, and wherein the chambers (7) are fan-shaped chambers; The variable stiffness support arm comprises an inner tube (1) connected to the charging and discharging module and an outer tube (2) sleeved on the inner tube (1), and blocking particles (5) are filled between the inner tube (1) and the outer tube (2); A support bar (4) is provided between each two chambers (7) of the bending section and the torsion section distributed radially along the sleeve (3); a reserved through hole (6) is provided in the support bar (4) along the axial direction of the sleeve (3); a pipe III (10) is provided in the reserved through hole (6); one end of the pipe III (10) is connected to the charging and discharging module, and the other end is connected to the chamber (7) of the other bending section; A pipe I (8) is provided in the chamber (7), and the charging and discharging medium of the chamber (7) in the curved section is connected to the charging and discharging module through the pipe I (8). One end of the pipe I (8) is directly connected to the chamber (7), and the other end passes through the chamber (7) of all the curved sections or torsional sections close to the fixed module (13) and is connected to the charging and discharging module.

2. The variable stiffness soft robotic arm for minimally invasive surgery according to claim 1, wherein: There are three chambers (7) distributed circumferentially around the central axis of the sleeve (3).

3. The variable stiffness soft robotic arm for minimally invasive surgery according to claim 1, wherein: The bending section and the torsion section are separated from each other.

4. The variable stiffness soft robotic arm for minimally invasive surgery according to claim 3, wherein: The wire loops (11) are closely arranged along the curved section.

5. The variable stiffness soft robotic arm for minimally invasive surgery according to claim 3, wherein: The helical wire (12) is in the form of a single helix, a double helix or a multi-helix with a large inclination angle and is arranged on the outer wall of the torsion section.

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