Soft robotic arm for safe feeding

Abstract

This invention discloses a soft robotic arm for safe feeding, belonging to the field of indoor robotics. The soft robotic arm includes multiple skeletal structures, elastic ball joints, and tendons. Each pair of skeletal structures is connected by an elastic ball joint. Each tendon includes three connecting lines. Each skeletal structure is a three-dimensional structure with a central axis. At three equidistant positions parallel to and on the central axis of each skeletal structure, the three connecting lines corresponding to the tendons pass through. One end of each connecting line is fixed to the first skeletal structure, passes through multiple intermediate skeletal structures, and exits from the last skeletal structure to connect to the control system. This invention possesses passive compliance in its mechanical structure and good motion response speed. When combined with a traditional rigid robotic arm, this invention can provide ample workspace for applications such as fully automated feeding.

Description

Technical Field

[0001] This invention belongs to the field of indoor robot technology, specifically relating to a soft robotic arm for safe feeding. Background Technology

[0002] Fully automated feeding is an important task in nursing care, and the design of feeding robots is becoming increasingly common. Currently, most feeding robots use traditional rigid robotic arms to perform actions. However, rigid robotic arms lack sufficient passive compliance when powered on, which can easily cause injury when food is placed in the mouth. Some research projects have attempted to use soft robots for feeding. While the inherent passive compliance of soft robots improves the safety of human-robot interaction, soft robots may have issues such as insufficient workspace and lower response speed, making it difficult to complete the entire feeding process efficiently. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention provides a combined rigid and flexible robotic arm for safe feeding, specifically a flexible robotic arm for safe feeding. This significantly improves safety and feeding efficiency.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A soft robotic arm for safe feeding includes multiple skeletal structures, elastic ball joints, and tendons. Each pair of skeletal structures is connected by an elastic ball joint. The tendons include three connecting lines. Each bone structure is a three-dimensional structure with a central axis. At three equidistant positions parallel to its own central axis, there are three connecting lines that run through the tendon. One end of each connecting line is fixed to the first bone structure, passes through multiple bone structures in the middle, and then emerges from the last bone structure to connect to the control system.

[0005] Furthermore, the elastic ball joint is located on the central axis of the three-dimensional structure, and the three positions of the three connecting lines of the penetrating tendon form the three vertices of an equilateral triangle.

[0006] Furthermore, the elastic ball joint is capable of bending and torsion within a preset range, and all elastic ball joints have the same mechanical properties.

[0007] Furthermore, the soft robotic arm also includes a coaxial cable reel for connecting the end of the soft robotic arm to the hard robotic arm, and is directly controlled by a rotary motor at the end of the hard robotic arm.

[0008] Furthermore, the coaxial cable reel includes two coaxial discs with a radius ratio of 1:2. The three connecting wires emerge from the last segment of the soft robotic arm's skeletal structure and are wound around the coaxial cable reel. Two connecting wires are wound in the same direction on the smaller disc, while the other connecting wire is wound in the opposite direction on the larger disc.

[0009] Furthermore, when the coaxial cable reel rotates, the sum of the lengths of the three connecting wires inside the soft robotic arm is equal.

[0010] The beneficial effects of this invention are as follows: This invention's soft robotic arm possesses passive compliance in its mechanical structure and excellent motion response speed. Interacting with the mouth using this soft robotic arm significantly improves safety; even if the person being fed suddenly moves during contact with the robotic arm, they will not be injured. Furthermore, using a traditional desktop hard robotic arm in conjunction with this soft robotic arm provides ample workspace and excellent motion response speed, thereby efficiently completing the fully automated feeding process. Attached Figure Description

[0011] Figure 1 This is a modeling and simulation diagram of a soft robotic arm for feeding according to the present invention; Figure 2 This is an actual machining diagram of a soft robotic arm for feeding according to the present invention; Figure 3 This is a partial enlarged view of the coaxial stranded coil of the present invention; Figure 4 This is an actual working diagram of the soft robotic arm and hard robotic arm used for feeding according to the present invention after assembly; Figure 5 This is a passive compliance test curve in the horizontal direction of a soft robotic arm for feeding according to the present invention. Figure 6 This is a test curve of the passive compliance of a soft robotic arm for feeding according to the present invention in the vertical direction.

[0012] Explanation of reference numerals in the attached figures

[0013] 1. Skeletal structure; 2. Elastic ball joint; 3. Tendon; 4. Coaxial strand. Detailed Implementation

[0014] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0015] This invention provides a soft robotic arm for safe feeding. The soft robotic arm is a rope-driven soft robotic arm with three tendons. It is controlled by only one motor, enabling it to be used for feeding tasks. By connecting this soft robotic arm with a traditional hard robotic arm and performing joint kinematic control calculations, the control of the spoon can be achieved, thus completing the fully automatic feeding process.

[0016] like Figure 1 As shown, the soft robotic arm comprises three parts: multiple skeletal structures 1, elastic ball joints 2, and tendons 3. The skeletal structures 1 are made of a material with negligible deformation. The tendons 3 include three connecting lines with negligible elongation. Every two skeletal structures 1 are connected by elastic ball joints 2, which can be bent and twisted within a certain range, and all elastic ball joints 2 have the same mechanical properties. The multiple skeletal structures 1 of the soft robotic arm have similar structures. Each skeletal structure 1 is a three-dimensional structure with a central axis. At three equidistant positions parallel to and on the central axis of each skeletal structure 1, three connecting lines from the tendons 3 are respectively inserted. One end of each connecting line is fixed to the first skeletal structure 1, passes through multiple skeletal structures 1 located in the middle sections, and exits from the last skeletal structure 1 to connect to the control system. Preferably, the skeletal structure 1 at the middle position of the present invention uses a triangular prism structure with an equilateral triangle as the base, and its bottom and top planes are modified into arc-like shapes. The elastic ball joint is located on the central axis of the three-dimensional structure, and the three positions of the three connecting lines of the penetrating tendon form the three vertices of the equilateral triangle. The skeletal structures 1 at both ends are slightly modified based on the triangular prism structure, and the final model is as follows. Figure 1 As shown, the entity is as follows Figure 2 As shown.

[0017] This invention relates to a tendon-shaped soft robotic arm with uniform thickness, characterized by an approximately constant sum of tendon lengths. To simplify the feeding task, only one motor is needed to control the soft robotic arm. The principle lies in using a coaxial stranded wire reel 4 with a radius ratio of 1:2 to pull three connecting wires, ensuring that the two uppermost connecting wires remain of equal length. Figure 3 The coaxial cable reel 4 shown is connected to the rigid robotic arm and controlled by a rotary motor at the end of the rigid robotic arm. The coaxial cable reel 4 comprises two coaxial discs with a radius ratio of 1:2. Three connecting wires extend from the last segment of the soft robotic arm's skeletal structure 1 and are wound onto the coaxial cable reel 4. Two connecting wires are wound in the same direction on the smaller disc, and the third connecting wire is wound in the opposite direction on the larger disc. When the coaxial cable reel 4 rotates, the sum of the lengths of the three connecting wires within the soft robotic arm is equal. When the two connecting wires on the smaller disc become longer, the other connecting wire on the larger disc simultaneously becomes shorter, and vice versa. This causes the soft robotic arm to change shape. Under this control method, the vertical tilt angle of the soft robotic arm's end can be changed, while the horizontal deflection and torsional angles remain unchanged.

[0018] The root of the aforementioned soft robotic arm is fixedly connected to the end of a traditional hard robotic arm, assembling it into a hybrid hard-soft robotic arm, such as... Figure 4As shown. In order to control the movement of the spoon, the kinematics of the rigid and flexible robotic arms are jointly calculated to determine the actions that the two need to perform in order to complete the feeding task.

[0019] For the physical entity of the soft robotic arm, the relationship between the thrust applied to its end effector and its position change was tested to demonstrate its passive compliance. Using the posture of the soft robotic arm as the spoon just enters the mouth as the test object, tests were conducted in the horizontal and vertical directions. The results are as follows: Figure 5 , Figure 6 As shown in the figure, the soft robotic arm of this structure has a positional adaptability of approximately 25cm in both the horizontal and vertical directions, and a small equivalent stiffness coefficient, exhibiting sufficient passive compliance for feeding tasks.

[0020] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A soft robotic arm for safe feeding, characterized in that, The soft robotic arm includes multiple skeletal structures (1), elastic ball joints (2), and tendons (3). Each pair of skeletal structures (1) is connected by an elastic ball joint (2). The tendon (3) includes three connecting lines, wherein... Each bone structure (1) is a three-dimensional structure with a central axis. At three positions in each bone structure (1) that are parallel to and equidistant from its own central axis, there are three connecting lines that pass through the tendon (3). One end of each connecting line is fixed on the first bone structure (1). After passing through multiple bone structures (1) located in the middle section, it passes out from the last bone structure (1) to connect to the control system. The soft robotic arm also includes a coaxial twisted wire reel (4), which consists of two coaxial discs with a radius ratio of 1:

2. The three connecting wires pass through the last segment of the skeleton structure (1) of the soft robotic arm and are wound on the coaxial twisted wire reel (4). Two connecting wires are wound in the same direction on the disc with a smaller radius, and the other connecting wire is wound in the opposite direction on the disc with a larger radius. When the coaxial twisted wire reel (4) rotates, the sum of the lengths of the three connecting wires inside the soft robotic arm is equal.

2. The soft robotic arm for safe feeding according to claim 1, characterized in that, The elastic ball joint (2) is located on the central axis of the three-dimensional structure, and the three positions of the three connecting lines of the penetrating tendon (3) form the three vertices of an equilateral triangle.

3. A soft robotic arm for safe feeding according to claim 1, characterized in that, The elastic ball joint (2) can be bent and twisted within a preset range, and all elastic ball joints (2) have the same mechanical properties.

4. A soft robotic arm for safe feeding according to claim 1, characterized in that, The coaxial strand (4) is used to connect the end of the soft robotic arm to the hard robotic arm and is directly controlled by the rotary motor at the end of the hard robotic arm.

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