A variable stiffness fiber-reinforced programmable soft actuator unit

Abstract

The present application relates to a kind of variable stiffness fiber reinforced programmable soft actuator unit, including flexible matrix and controllable module, flexible matrix is pipeline-like, and controllable module is fixed on the outer layer of flexible matrix distribution;Controllable module uses single-layer module or the multi-layer module arranged inside and outside;Each layer of controllable module is wound by at least one variable stiffness fiber according to certain angle and direction;The control line of connection controllable module is distributed in the inner cavity of flexible matrix, and is connected with external control system;The two ends of the inner cavity of flexible matrix are blocked and leave medium filling and discharging mouth, and fluid medium is filled in the inner cavity;Controllable module state is two kinds of flexible state and rigid state, when carrying out the deformation control of soft actuator unit, by controlling part variable stiffness fiber to be rigid state, another part variable stiffness fiber is flexible state, realizes the deformation control of soft actuator unit.

Description

Technical Field

[0001] This invention belongs to the field of soft robot technology, specifically relating to a variable stiffness fiber-reinforced programmable soft actuator unit. Background Technology

[0002] Soft robots, made of flexible materials, possess excellent safety, continuous deformation capabilities, mobility, user-friendly interactivity, and biocompatibility. Their high compliance and degrees of freedom allow them to adapt well to unstructured environments. However, due to their flexible materials, soft robots theoretically possess unlimited degrees of freedom. Combined with the complexity of their actuation methods, structure, and soft materials, achieving intelligent and precise control of soft robots is challenging. Unlike traditional rigid robots, numerous factors make it difficult to establish accurate mathematical models for soft robots, making their control highly challenging and difficult to integrate with the technical experience of traditional rigid robotic arms. Currently, most control methods for soft mechanical actuators are complex, involving multiple air chambers and resulting in cumbersome control systems. Programmability is an important direction for controlling soft robot actuators, but current programmable solutions still suffer from problems such as insufficient flexibility. Therefore, researching a single-cavity (airway) programmable soft robot actuator unit is essential. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a variable stiffness fiber reinforced programmable software driver unit.

[0004] The above-mentioned objective of this invention is achieved through the following technical solution:

[0005] A variable stiffness fiber-reinforced programmable software actuator unit is characterized by comprising a flexible substrate and controllable modules. The flexible substrate is tubular, and the controllable modules are distributed and fixed on the outer layer of the flexible substrate. The controllable modules are single-layer modules or multi-layer modules arranged internally and externally. Each layer of controllable modules is formed by winding at least one variable stiffness fiber at a certain angle and direction. The control lines connecting the controllable modules are distributed in the inner cavity of the flexible substrate and connected to an external control system. The two ends of the inner cavity of the flexible substrate are sealed and have medium filling / discharging nozzles, and the inner cavity is filled with a fluid medium.

[0006] The controllable module has two states: flexible and rigid. When controlling the deformation of the soft actuator unit, the deformation of the soft actuator unit is achieved by controlling some of the variable stiffness fibers to be in a rigid state and others to be in a flexible state.

[0007] Moreover, the variable stiffness fiber is made of silicone tubes injected with low melting point alloy, elastic filaments impregnated with low melting point alloy, and shape memory polymer fibers.

[0008] Furthermore, the fluid medium may be air, hydraulic oil, or flowing particles.

[0009] Furthermore, the controllable module consists of a first layer controllable module and a second layer controllable module; the first layer controllable module consists of two variable stiffness fibers with small winding angles and opposite winding directions; the second layer controllable module consists of two outer layer variable stiffness fibers with large winding angles and opposite winding directions; when the two inner layer variable stiffness fibers are in a rigid state and the two outer layer variable stiffness fibers are in a flexible state, the actuator unit realizes axial tension; when the two inner layer variable stiffness fibers are in a flexible state and the two outer layer variable stiffness fibers are in a rigid state, the actuator unit realizes axial extension and retraction; when one of the inner layer variable stiffness fibers is in a rigid state and the other variable stiffness fibers are in a flexible state, the actuator realizes axial torsion and axial tension, wherein the torsion direction is opposite to the winding direction of the variable stiffness fiber in the rigid inner state.

[0010] The advantages and positive effects of this invention are as follows:

[0011] This invention involves winding one or more linear modules with controllable morphology onto the outer layer of a tubular flexible substrate. By controlling the states of these controllable modules with different winding states distributed on the flexible substrate, the invention enables the flexible substrate to perform actions such as expansion, contraction, and torsion under inflated conditions. The magnitude of the expansion and contraction and the angle of torsion can be adjusted by regulating the inflation pressure. The controllable modules exist in two states: a difficult-to-deform state and a easily deformable state. This allows for control of modules with different winding angles and directions to achieve different actions. The invention also enables programmable control of the software actuator unit, and further programmable control can be achieved by combining various actuator modes. Attached Figure Description

[0012] Figure 1 This is a simplified structural diagram of the two-layer controllable module of the present invention. 1a is an external schematic diagram and 1b is a partial sectional view.

[0013] Figure 2 This is a schematic diagram of the working principle of the two-layer controllable module of the present invention; 2a is a schematic diagram of elongation and counterclockwise torsion around the axis; 2b is a schematic diagram of elongation and clockwise torsion of the axis; 2c is a schematic diagram of axial stretching motion; 2d is a schematic diagram of axial telescopic motion; 2e is a schematic diagram of bending motion.

[0014] Figure 3 This is a structural schematic diagram of the first embodiment of the present invention; 3a is an external schematic diagram, and 3b is a partial sectional view;

[0015] Figure 44a is a schematic diagram of the motion state of the first embodiment of the present invention; 4b is a schematic diagram of the axial stretching of the driver unit; 4c is a schematic diagram of the axial extension and retraction of the driver; and 4c is a schematic diagram of the counterclockwise torsion and axial stretching of the driver around the axis.

[0016] Figure 5 This is a structural schematic diagram of the second embodiment of the present invention; 5a is a schematic diagram of the appearance in the initial state, and 5b is a schematic diagram of the appearance after deformation. Detailed Implementation

[0017] The structure of the present invention will be further described below with reference to the accompanying drawings and embodiments. It should be noted that these embodiments are descriptive and not limiting.

[0018] For an example of a variable stiffness fiber-reinforced programmable software driver unit, please refer to [link / reference]. Figures 1-5 Its invention is based on the following: it mainly consists of a flexible substrate and controllable modules distributed and fixed on the outer layer of the flexible substrate.

[0019] The flexible substrate is made of flexible material and is a flexible pipe with uniform material distribution. Its specific shape and size can be manufactured into a mold according to actual needs. The fluid flexible material is injected into the mold and solidified.

[0020] Depending on the control principle, the controllable module can be a low-melting-point alloy controllable module, a thermoplastic starch controllable module, or a shape memory polymer (SMP) controllable module, etc., all meeting the control requirements. The controllable module can be a single-layer module or a multi-layer module with internal and external components. Each layer of the controllable module consists of at least one variable-stiffness fiber wound at a specific angle and direction. The control circuitry connecting the controllable modules is distributed within the flexible matrix cavity and connected to the external control system; simultaneously, the interior of the pipe also serves as a fluid medium cavity.

[0021] Based on actual needs, both ends of the inner cavity of the flexible substrate with the controllable module bonded together are sealed. The sealing can be achieved by: manufacturing a mold, injecting a fluid flexible material, and curing it. A medium filling / discharging nozzle is reserved at one end of the seal to allow fluid medium to be filled into the inner cavity and some fluid medium to be discharged from the inner cavity, thereby regulating the pressure in the inner cavity and ultimately adjusting the deformation of the soft actuator, such as the extension, twisting angle, and bending angle of the soft actuator unit.

[0022] The controllable module has two states: flexible and rigid. When controlling the deformation of the soft actuator unit, the deformation of the entire unit is controlled by controlling some variable stiffness fibers to be in a rigid state and others to be in a flexible state. The deformation control method differs for variable stiffness fibers with different control principles. Specifically:

[0023] Variable stiffness fibers based on low-melting-point alloys become flexible when heated (usually by applying electricity) and become rigid when cooled by removing the power.

[0024] Shape memory polymer fibers become flexible when heated (usually by applying electricity) and become rigid when cooled and de-energized.

[0025] like Figure 1 The image shows a driver unit with two programmable modules and a partial cross-sectional view. It mainly consists of a flexible substrate 1, a first-layer controllable module 2, and a second-layer controllable module 3. Its specific driving principle is as follows: Figure 2 For example, when other modules are in a flexible state, leaving only one clockwise winding module in a rigid state, after inflation, the driver unit produces elongation and counterclockwise torsion around the axis, with the elongation and torsion angle controlled by air pressure; when other modules are in a flexible state, leaving only one counterclockwise winding module in a rigid state, after inflation, the driver unit produces elongation and clockwise torsion around the axis, with the elongation and torsion angle controlled by air pressure; when other modules are in a flexible state, leaving only a set of small-angle (winding angle θ less than 45°, winding direction opposite) winding modules in a rigid state, after inflation, the driver unit produces axial stretching motion, with the stretching amount controlled by air pressure; when other modules are in a flexible state, leaving only a set of large-angle (winding angle θ greater than 45°, winding direction opposite) winding modules in a rigid state, after inflation, the driver unit produces axial extension and contraction motion, with the extension and contraction amount controlled by air pressure; when other modules are in a flexible state, and one side of the axially restricting winding module is in a rigid state, after inflation, the driver unit produces bending motion.

[0026] Example 1:

[0027] like Figure 3 The diagram shows a programmable driver unit with two layers of controllable modules and a partial cross-sectional view, comprising a flexible substrate 1, a first-layer programmable module 2, and a second-layer programmable module 3. The first layer, or inner layer, programmable module 2, is a small-angle winding module with a winding angle of 10°, comprising a clockwise winding module 2.1 and a counterclockwise winding module 2.2. The second layer, or outer layer, programmable module 3, is a large-angle winding module with a winding angle of 55°, comprising a clockwise winding module 3.1 and a counterclockwise winding module 3.2. The programmable modules are low-melting-point alloy modules, rigid at room temperature and flexible after being heated. Programmable control can be achieved by controlling the heating of each module, such as... Figure 4 As shown, the small-angle controllable module of the control actuator unit is in a rigid state, while the others are in a flexible state (electrically heated), such as... Figure 4As shown in Figure a, the actuator unit achieves axial tensile motion after inflation. The large-angle controllable module of the actuator unit is in a rigid state, while the others are in a flexible state (electrically heated), such as... Figure 4 As shown in Figure b, the actuator achieves axial telescopic movement after inflation. The clockwise winding module in the small-angle controllable module of the actuator unit is in a rigid state, while the others are in a flexible state (electrically heated), such as... Figure 4 As shown in c, after inflation, the actuator achieves counterclockwise torsion around the axis and axial stretching motion;

[0028] By pairing this mode of actuator unit with a programmable control, programmed actions can be achieved through a single airway.

[0029] Example 2:

[0030] like Figure 5 The diagram shows a software driver containing three programmable software driver units, each with a single-layer controllable module. The first programmable software driver unit's controllable module 4 is formed by winding two variable stiffness fibers (labeled 4.1 and 4.2 respectively) at an angle θ = 5°, in opposite directions. The second programmable software driver unit's controllable module 5 is formed by winding three variable stiffness fibers (labeled 5.1, 5.2, and 5.3 respectively), with the three fibers wound in the same way and evenly distributed circumferentially around the controllable module. The third programmable software driver unit's controllable module 6 is formed by winding two variable stiffness fibers (labeled 6.1 and 6.2 respectively) at an angle θ = 10°, in opposite directions. By controlling the variable stiffness fibers 4.1, 5.1, 6.1, and 6.2 to be in a rigid state, and the remaining variable stiffness fibers to be in a flexible state, and by inflating and pressurizing them, actions such as 5b can be achieved: the first programmable software actuator unit realizes counterclockwise rotation and axial elongation, the second programmable software actuator unit realizes directional bending, and the third programmable software actuator unit realizes axial elongation.

[0031] Although embodiments and drawings of the present invention have been disclosed for illustrative purposes, those skilled in the art will understand that various substitutions, variations and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the contents disclosed in the embodiments and drawings.

Claims

1. A variable stiffness fiber-reinforced programmable software driver unit, characterized in that: The device includes a flexible substrate and controllable modules. The flexible substrate is tubular, and the controllable modules are distributed and fixed on the outer layer of the flexible substrate. The controllable modules are single-layer modules or multi-layer modules with internal and external components. Each layer of controllable modules is formed by winding at least one variable stiffness fiber at a certain angle and direction. The control lines connecting the controllable modules are distributed in the inner cavity of the flexible substrate and connected to an external control system. The two ends of the inner cavity of the flexible substrate are sealed and have medium filling and discharging nozzles, and the inner cavity is filled with a fluid medium. The controllable module has two states: flexible and rigid. When performing deformation control of the soft actuator unit, the deformation control of the soft actuator unit is achieved by controlling some variable stiffness fibers to be in a rigid state and others to be in a flexible state. The variable stiffness fiber is made of silicone tubes injected with low melting point alloy, elastic filaments impregnated with low melting point alloy, and shape memory polymer fibers. The controllable module consists of a first layer controllable module and a second layer controllable module. The first layer controllable module consists of two variable stiffness fibers with small winding angles and opposite winding directions. The second layer controllable module consists of two outer layer variable stiffness fibers with large winding angles and opposite winding directions. When the two inner layer variable stiffness fibers are in a rigid state and the two outer layer variable stiffness fibers are in a flexible state, the actuator unit performs axial stretching. When the two inner layer variable stiffness fibers are in a flexible state and the two outer layer variable stiffness fibers are in a rigid state, the actuator unit performs axial extension and retraction. When one of the inner layer variable stiffness fibers is in a rigid state and the other variable stiffness fibers are in a flexible state, the actuator performs torsion around the axis and axial stretching, wherein the torsion direction is opposite to the winding direction of the inner layer variable stiffness fiber in the rigid state.

2. The variable stiffness fiber-reinforced programmable software driver unit according to claim 1, characterized in that: The fluid medium may be air, hydraulic oil, or flowing particles.

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