EARLIEST PRIORITY DATE

This Application claims priority from a Complete patent application filed in India having Patent Application No. 202211057955, filed on October 10, 2022, and titled “AN ACTUATOR-DRIVEN BI-DIRECTIONAL ROBOTIC FINGER FOR ENHANCING GRASPING FORCE FOR END EFFECTORS AND METHOD THEREOF”.

FIELD OF INVENTION

Embodiments of a present disclosure relate to the field of robotics, and more particularly to an actuator-driven bi-directional robotic finger for enhancing grasping force for end effectors and a method thereof.

BACKGROUND

About fifteen percent of the world’s population lives with a disability and cannot perform their daily tasks. Also, about fifteen million people suffer from stroke and find it challenging to live an independent life. Currently, there are several equipment to aid such people to complete daily chores such as wheelchairs, walking aids, hearing aids, artificial limbs, and the like. Specifically, in case of a stroke or an amputation of any body part of a person, artificial limbs are useful. Artificial limbs are used when a person’s arm, leg or finger is missing or is not working due to a stroke or any other reasons.

Several types of artificial limbs include supernumerary limbs, robotic limbs, and the like. Supernumerary robotic limbs are a new type of wearable human auxiliary equipment which is currently used in many application fields. SRL can perform multiple functions and can become an extra leg or arm that can support the human body and assist in multiple operations. Conventional supernumerary robotic limbs (SRL) are based on traditional actuation systems such as electrical motors, pneumatic actuators, pulling cable actuation and electroactive polymer actuators. It is necessary to deploy two actuators for antagonistic action. These supernumerary robotic limbs (SRL) become very heavy and energy efficient. The existing SRL fails to produce high grasping force. Also, the currently existing artificial limbs are not completely wearable and portable. Further, the currently existing limbs require lubrication in joints which limits the application of the limb in water and dusty environment. There is need of a finger with an actuator that facilitates gentle holding of the object.

Hence, there is a need for an actuator-driven bi-directional robotic finger for enhancing the grasping force for end effectors and a method thereof which addresses the aforementioned issues.

BRIEF DESCRIPTION

In accordance with one embodiment of the disclosure, an actuator-driven bidirectional robotic finger for enhancing grasping force for end effectors is provided. The robotic finger includes a motor assembly and a clasping assembly. The motor assembly includes a motor, an encoder, an angular bearing, a string. The motor is configured to rotate a shaft mounted on the motor for generating a twisting actuation effect. The encoder is operatively connected with the motor and configured to measure the number of revolutions of the motor. The angular bearing is operatively coupled with the encoder and disposed on a connector hook. The angular bearing bears an axial load of the object. The string co-axially connected to the shaft through the connector hook. The twisting actuation by the motor generates a twisting string actuation effect on the string. The clasping assembly is operatively coupled with the motor assembly. The clasping assembly is configured to grasp the object. The clasping assembly includes a plurality of phalanges, a plurality of beams, and a plurality of bending structure. The plurality of phalanges is connected to the shaft by means of the string. The plurality of phalanges is rigid to provide a holding strength to the object. The plurality of beams is adapted to connect two adjacent phalanges at a first end of each of the plurality of phalanges. The plurality of beams is configured to create a passive return rotation joint at the plurality of phalanges. The passive return rotation joints allow an extension action by pumping back elastic energy to the clasping assembly. The plurality of beams is configured create a buckle during flexion action. The buckling of the plurality of beams creates a large actuating force on the passive return rotation joint to collapse the plurality of beams and produce a flexion action for holding the object. The plurality of bending structure is adapted to bend for connecting the two adjacent phalanges at a second end of each of the plurality of phalanges, wherein each bending structure is configured to bend during flexion action and passively extend the plurality of phalanges during the extension action.

In accordance with another embodiment, a method for operating an actuator-driven bi-directional robotic finger for enhancing grasping force for end effectors is provided. The method includes rotating, by a motor of a motor assembly, a shaft mounted on the motor for generating a twisting actuation effect. The method also includes encoding, by an encoder of the motor assembly the number of revolutions of the motor. Further, the method includes bearing, by and angular bearing of the motor assembly, an axial load of the object. Furthermore, the method generating, by a string of the motor assembly, generating a twisting string actuation effect on the string. Furthermore, the method includes connecting, by the string of the motor assembly, the plurality of phalanges of a clasping assembly, wherein the plurality of phalanges is rigid to provide a holding strength to the object. Furthermore, the method includes creating, by a plurality of beams of the clasping assembly, a passive return rotation joint at the plurality of phalanges, wherein the passive return rotation joints allow an extension action by pumping back elastic energy to the clasping assembly. Furthermore, the method includes buckling, by the plurality of beams of the clasping assembly, the plurality of beams and creating a large actuating force on the passive return rotation joint to collapse the plurality of beams and produce a flexion action for holding the object. Furthermore, the method includes bending, by the plurality of bending structure of the clasping assembly, adapted to bend for connecting the two adjacent phalanges at a second end of each of the plurality of phalanges, wherein each bending structure configured to bend during flexion action and passively extend the plurality of phalanges during the extension action.

To further clarify the advantages and features of the present disclosure, a more particular description of the disclosure will follow by reference to specific embodiments thereof, which are illustrated in the appended figures. It is to be appreciated that these figures depict only typical embodiments of the disclosure and are therefore not to be considered limiting in scope. The disclosure will be described and explained with additional specificity and detail with the appended figures.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure will be described and explained with additional specificity and detail with the accompanying figures in which:

FIG. 1 is a schematic representation of an actuator-driven bi-directional robotic finger for enhancing grasping force for end effectors in an embodiment of the present disclosure;

FIG. 2 is a schematic representation of the actuator-driven bi-directional robotic finger for enhancing grasping force for end effectors in an operating position of FIG. 1 in accordance with an embodiment of the present disclosure;

FIG. 3 is a schematic representation of the actuator-driven bi-directional robotic finger for enhancing grasping force for end effectors in an operating position of FIG. 1 in accordance with another embodiment of the present disclosure;

FIG. 4 is an exploded detailed cross-sectional view of the plurality of beams of FIG.

1 in accordance with an embodiment of the present disclosure; FIG. 5 is an exploded detailed cross-sectional view of the joint of the clasping assembly with the motor assembly by means of the connector hook and the string of FIG. 1 in accordance with an embodiment of the present disclosure; and

FIG. 6 is a flow chart representing steps involved in a method for an operation of actuator-driven bi-directional robotic finger for enhancing grasping force for end effectors in accordance with an embodiment of the present disclosure.

Further, those skilled in the art will appreciate that elements in the figures are illustrated for simplicity and may not have necessarily been drawn to scale. Furthermore, in terms of the construction of the device, one or more components of the device may have been represented in the figures by conventional symbols, and the figures may show only those specific details that are pertinent to understanding the embodiments of the present disclosure so as not to obscure the figures with details that will be readily apparent to those skilled in the art having the benefit of the description herein.

DETAILED DESCRIPTION

For the purpose of promoting an understanding of the principles of the disclosure, reference will now be made to the embodiment illustrated in the figures and specific language will be used to describe them. It will nevertheless be understood that no limitation of the scope of the disclosure is thereby intended. Such alterations and further modifications in the illustrated system, and such further applications of the principles of the disclosure as would normally occur to those skilled in the art are to be construed as being within the scope of the present disclosure.

The terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process or method that comprises a list of steps does not include only those steps but may include other steps not expressly listed or inherent to such a process or method. Similarly, one or more devices or sub-systems or elements or structures or components preceded by "comprises... a" does not, without more constraints, preclude the existence of other devices, sub-systems, elements, structures, components, additional devices, additional sub-systems, additional elements, additional structures or additional components. Appearances of the phrase "in an embodiment", "in another embodiment" and similar language throughout this specification may, but not necessarily do, all refer to the same embodiment.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this disclosure belongs. The system, methods, and examples provided herein are only illustrative and not intended to be limiting.

In the following specification and the claims, reference will be made to a number of terms, which shall be defined to have the following meanings. The singular forms “a”, “an”, and “the” include plural references unless the context clearly dictates otherwise.

Embodiments of the present disclosure relates to Antagonistic Supernumerary Robotic Limb (ASRL). As used herein, the term “robotic finger” defined as an artificial complex robot, which is limb like structure that functions as a human finger. Further, the robotic finger described hereafter in FIG. 1 is the actuator-driven bi-directional robotic finger for enhancing grasping force for end effectors.

FIG. 1 is schematic representation of actuator-driven bi-directional robotic finger for enhancing grasping force for end effectors in accordance with an embodiment of the present disclosure. The robotic finger (100) includes a motor assembly (102) and a clasping assembly (116). The motor assembly (102) includes a motor (104), an encoder (108), an angular bearing (110), and a string (114). The motor (104) is configured to rotate a shaft (106) mounted on the motor (104) for generating a twisting actuation effect. In one embodiment, the motor (104) is small in size, hence the robotic finger (100) becomes wearable on a user’s hand.

The encoder (108) is operatively connected with the motor (104) and configured to measure the number of revolutions of the motor (104). In one embodiment, the encoder (108) is a combination of circuits, which generates a specific code. The encoder (108) performs the reverse operation of a decoder. The encoder (108) is used for measuring the number of rotations done by the shaft (106) of the motor (104).

The angular bearing (110) is operatively coupled with the encoder (108) and disposed on a connector hook (112). The angular bearing (110) bears an axial load of the object to be grasped. In one embodiment, the angular bearing (110) is configured with inner and outer rings that are displaced relative to each other in the direction of the bearing axis. As a result, the angular bearing (110) accommodates combined loads, that is both radial and axial loads.

The string (114) is co-axially connected to the shaft (106) through the connector hook (112). The twisting actuation by the motor (104) generates a twisting string actuation effect on the string (114). In one embodiment, when the motor (104) rotates the shaft (106), the twisting actuator effect is created to twist the string (114) connected to the connector hook (112). The string (114) twists to generate the flexion action.

The clasping assembly (116) is operatively coupled with the motor assembly (102). The clasping assembly (116) is configured to grasp the object that the user desires. Typically, the object may be defined as any object that differs in size, shape and weight. Examples of the object include, but is not limited to, a fruit, a cup, a bottle and a pen. The clasping assembly (116) includes a plurality of phalanges (118), a plurality of beams (120), and a plurality of bending structure (122). The plurality of phalanges (118) is connected to the shaft (106) in a series by means of the string (114). The plurality of phalanges (118) is rigid to provide a holding strength to the object.

The plurality of beams (120) is adapted to connect two adjacent phalanges at a first end of each of the plurality of phalanges. The plurality of beams (120) is configured to create a passive return rotation joint at the plurality of phalanges (118). The passive return rotation joints allow an extension action by pumping back elastic energy to the clasping assembly (116). The plurality of beams (120) is configured to create a buckle during flexion action. The buckling of the plurality of beams (120) creates a large actuating force on the passive return rotation joint to collapse the plurality of beams (120) and produce a flexion action for holding the object. In one embodiment, the plurality of beams (120) is in pair which connects two adjacent the plurality of phalanges (118).

The plurality of bending structure (122) is adapted to bend for connecting the two adjacent phalanges at a second end of each of the plurality of phalanges, wherein each bending structure is configured to bend during flexion action and passively extend the plurality of phalanges (118) during the extension action. In one embodiment, the plurality of bending structures (122) is elastic in nature.

FIG. 2 is a schematic representation of the actuator-driven bi-directional robotic finger for enhancing grasping force for end effectors in an operating position of FIG. 1 in accordance with an embodiment of the present disclosure.

FIG. 2 illustrates the operating position of the robotic finger (100), in accordance with an embodiment of the present disclosure of FIG. 1. In an exemplary embodiment, the robotic finger (100) is wearable on the wrist of a user. The robotic finger (100) includes the motor assembly (102) and the clasping assembly (116). The motor assembly (102) includes a motor (104), an encoder (108), an angular bearing (110), and a string (114). In one embodiment, the robotic finger (100) is wearable as a supplementary finger on a wrist of the user with the aid of a wrist strap (130), wherein the robotic finger (100) and the wrist strap (130) is coupled to each other with a motor holder (132).

In one embodiment, the motor (104) is operated on a power supply. In another embodiment, the motor (104) is small in size. In one embodiment, the shaft (106) functions as a -ratio gear, which can generate high output force with low input torque. In one embodiment, the connector hook (112) is configured to passively extend the plurality of phalanges (118) during the extension action. In another embodiment, the connector hook (112) is adapted to hold the string (114). In such an embodiment, the connector hook (112) is mounted inside the angular bearing. Further, in one embodiment, the connector hook (112) is connected to the shaft (106).

In one embodiment, the plurality of beams (120) is configured with a plurality of ends comprising a protruding part (124). In one embodiment, the protruding part (124) is configured to fit in a plurality of slots (126) on the plurality of phalanges (118). In another embodiment, the protruding part (124) is fitted in the plurality of slots (126) and provides strength to the robotic finger (100) in the operating position. In one embodiment, the plurality of beams (120) in the operating position collapses and allows the plurality of phalanges (118) to come close to each other to hold the object. In another embodiment, the plurality of beams (120) when in the operating position, collapses at a distance corresponding to the size of the object to be hold.

In one embodiment, the plurality of bending structure (122) is made of an elastic and soft material to provide flexibility. In another embodiment, the plurality of bending structures (122) is elastic and bends to allow the plurality of phalanges (118) to come close to each other to hold the object. The bending position of the plurality of bending structure (122) is based on the size of the object to be held.

FIG. 3 is a schematic representation of the actuator-driven bi-directional robotic finger for enhancing grasping force for end effectors in an operating position of FIG. 1 in accordance with another embodiment of the present disclosure. In such an embodiment, the user accommodates two robotic fingers namely, a first robotic finger (100a) and a second robotic finger (100b). In one embodiment, the robotic finger (100) actuates in both directions using a single actuator so that the finger is lightweight, compact, energy-efficient and cheap. The robotic finger (100) produces a high grasping force at the cost of low input energy due to the proposed finger joints. It must be noted that the user may accommodate multiple robotic fingers based on the user’s requirement and may not be limited to the said number of two robotic fingers.

FIG. 4 is an exploded detailed cross-sectional of the plurality of beams (120) of FIG. 1 in accordance with an embodiment of the present disclosure. In one embodiment, the plurality of beams (120) is configured with a plurality of ends comprising a protruding part (124) which is further configured to fit in a plurality of slots (126) on the plurality of phalanges (118). In another embodiment, the plurality of beams (120) when in the operating position, collapses at a distance corresponding to the size of the object to be held. In one embodiment, the pair of beams (120) with arc shape is shown. The pair of beams (120) is fitted at the top portion of the plurality of phalanges (118). In one embodiment, the plurality of bending structure (122) is fitted at the bottom portion of the plurality of phalanges (118). The plurality of bending structure (122) is bent to allow the plurality of phalanges (118) to come close to each other to hold the object. The sheet (128) disposed on the plurality of phalanges (118) facilitates a grip to hold the object for long time. In one embodiment, the robotic finger (100) is maintenance-free due to the absence of conventional bearing in the proposed finger joint.

FIG. 5 illustrates an exploded detailed cross-sectional of the joint of the clasping assembly (116) with the motor assembly (102) by means of the connector hook (112) and the string (114). The joint is represented by the string (114) connected to the connector hook (112) and the phalange (118) connected to the motor assembly (102). The connector hook (112) is configured to passively extend the plurality of phalanges (118) during the extension action. In another embodiment, the connector hook (112) is adapted to hold the string (114). In such an embodiment, the connector hook (112) is mounted inside the angular bearing. Further, in one embodiment, the connector hook (112) is connected to the shaft (106).

In one embodiment, the Antagonistic Supernumerary Robotic Limbs (ASRL) is a wearable finger. For flexion motion of a limb, a single twisting string actuator (TSA) is used with passive return rotational (PRR) joint mechanism. In the TSA, a pair of strings co-axially attached to the motor shaft acts as a high-ratio gear, which may generate high output force with low input torque. The twisting string actuation generates a large actuating force on the PRR joints to collapse the beam and produce finger flexion motion. In the ASRL, several PRR is connected in series which store the energy during flexion cycle and pump it back in extension of the finger. The PRR joints have a similar force-displacement profile due to the beam-buckling mechanism, so the grasping force was high throughout the finger flexion motion. The PRR joints are solely responsible for the finger’s extension without any additional actuator. The PRR joints pump back the elastic energy to the finger during extension.

FIG. 6 is a flow chart representing steps involved in a method (200) for operating an actuator-driven bi-directional robotic finger for enhancing grasping force for end effectors in accordance with an embodiment of the present disclosure. The method (200) includes rotating, by a motor of a motor assembly, a shaft mounted on the motor for generating a twisting actuation effect in step (202). The method also includes operating, the motor on a power supply. The method also includes function, by the shaft as a -ratio gear, which may generate high output force with low input torque.

The method (200) also includes encoding, by an encoder of the motor assembly the number of revolutions of the motor in step (204). The method also includes combining, circuits, to generate a specific code. The method also includes performing, the reverse operation of a decoder. The method also includes measuring, by the encoder, the number of rotations done by the shaft of the motor.

Further, the method (200) includes bearing, by and angular bearing of the motor assembly, an axial load of the object in step (206). The method also includes, displacing, inner and outer rings relative to each other in the direction of the bearing axis. The method also includes accommodating, by the angular bearing combined loads, that is both radial and axial loads. Furthermore, the method (200) includes generating, by a string of the motor assembly, generating a twisting string actuation effect on the string in step (208). The method also includes passively extending, by the connector hook, the plurality of phalanges during the extension action. The method also includes mounting, the connector hook is mounted inside the angular bearing. The method also includes connecting, the connector hook is connected to the shaft

Furthermore, the method (200) includes connecting, by the string of the motor assembly, the plurality of phalanges of a clasping assembly, wherein the plurality of phalanges is rigid to provide a holding strength to the object in step (210). The method also includes twisting, the string by rotating the motor to for holding the object.

Furthermore, the method (200) includes creating, by a plurality of beams of the clasping assembly, a passive return rotation joint at the plurality of phalanges, wherein the passive return rotation joints allow an extension action by pumping back elastic energy to the clasping assembly in step (212). The method also includes fitting, a plurality of slots on the plurality of phalanges by means of a protruding part. The method also includes collapsing, the plurality of beams to allow the plurality of phalanges to come close to each other to hold the object.

Furthermore, the method (200) includes buckling, by the plurality of beams of the clasping assembly, the plurality of beams and creating a large actuating force on the passive return rotation joint to collapse the plurality of beams and produce a flexion action for holding the object in step (214). The method also includes collapsing, the plurality of beams at a distance corresponding to the size of the object to be hold.

Furthermore, the method (200) includes bending, by the plurality of bending structure of the clasping assembly, adapted to bend for connecting the two adjacent phalanges at a second end of each of the plurality of phalanges, wherein each bending structure is configured to bend during flexion action and passively extend the plurality of phalanges during the extension action in step (216). The method also includes bending, by the plurality of bending structure, which is elastic in nature, to provide flexibility in operating position.

Various embodiments of the present disclosure enable operating a robotic limb for enhancing the grasping force of an object. The robotic finger disclosed in the present disclosure is lightweight as the finger includes a small-sized motor. The robotic finger is easily wearable and hence easy to use. The robotic finger in the present disclosure is portable. The robotic finger does not require additional lubrication for joints. Due to this, the robotic finger is used in water and in a dusty environment. The robotic finger disclosed in the present disclosure automatically adjusts to grasp an object corresponding to the size of the object. The robotic finger is having high grasping force and holds the object smoothly. The robotic finger is maintenance-free due to the absence of conventional bearing in the proposed finger joint. The robotic finger disclosed in the present disclosure includes a soft-rigid modular structure to adapt to any random object's shape.

Further, the robotic finger disclosed in the present disclosure may be used in several other applications. For instance, the robotic finger can be used for developing an anthropomorphic robotic hand to perform all grasping methods. The robotic finger (100) can also be used to develop a lightweight, compact, energy-efficient finger for drone’s aerial manipulation, marine manipulation applications, and grasping of agricultural products including fruits and vegetables. Furthermore, the robotic finger disclosed in the present disclosure can be used to develop a long single-finger end-effector for adaptive grasping like an elephant trunk.

While specific language has been used to describe the disclosure, any limitations arising on account of the same are not intended. As would be apparent to a person skilled in the art, various working modifications may be made to the method in order to implement the inventive concept as taught herein.

The figures and the foregoing description give examples of embodiments. Those skilled in the art will appreciate that one or more of the described elements may well be combined into a single functional element. Alternatively, certain elements may be split into multiple functional elements. Elements from one embodiment may be added to another embodiment. For example, order of processes described herein may be changed and are not limited to the manner described herein. Moreover, the actions of any flow diagram need not be implemented in the order shown; nor do all of the acts need to be necessarily performed. Also, those acts that are not dependent on other acts may be performed in parallel with the other acts. The scope of embodiments is by no means limited by these specific examples.