Robot arm and robot system including the same

Abstract

In certain embodiments, a robotic arm and a robotic system including the robotic arm are provided. In some embodiments, a robotic arm includes a base unit including a base motor and a base, and a drive unit including a quadrilateral linkage, a first drive motor, and a second drive motor. Other example embodiments are described herein. In some embodiments, the robotic arm enables both rotational and linear motion while minimizing the physical footprint for easier storage and transportation.

Description

TECHNICAL FIELD

[0001] The present application relates to robots, and in particular to robotic arms and robotic systems comprising robotic arms. BACKGROUND

[0002] Robotic arms are widely used in various industrial applications, many of which systems rely on serial or parallel linkages to provide multi-degree of freedom (DoF) movement. Conventional robotic arms typically face challenges such as limited workspaces, complex mechanical designs, and large physical footprints. As industries demand more compact, flexible, and versatile robotic solutions, new robotic designs are needed to improve efficiency in confined spaces while maintaining functionality. There is an urgent need for robotic arms and systems that can achieve both rotational and linear movements while minimizing their spatial footprints for easier storage and transportation, which is critical in modern robotics. SUMMARY

[0003] In certain embodiments, the present application addresses at least some of these challenges by proposing a modular, foldable robotic arm design that combines the benefits of serial linkages with a compact folding structure.

[0004] Disclosed herein is a novel robotic arm and system thereof that uses a foldable structure for both linear and rotational movements.

[0005] In some embodiments, the robotic arm comprises a base unit and a drive unit operatively connected to each other.

[0006] In some embodiments, the base unit comprises a base motor operatively connected to the drive unit and configured to drive the drive unit to move in at least one degree of freedom, and a base configured to support the base motor and the drive unit.

[0007] In some embodiments, the drive unit comprises a quadrilateral linkage, a first drive motor operatively connected to the quadrilateral linkage and configured to drive the quadrilateral linkage to switch between at least a retracted state and an extended state, and a second drive motor operatively connected to the quadrilateral linkage and configured to drive the quadrilateral linkage to switch from at least the extended state to at least one curved state.

[0008] The present utility model has many advantages. In certain embodiments, this design enables the robot arm to perform complex tasks that are traditionally performed by a serial robot arm, while also incorporating folding and linear motion capabilities, thereby allowing it to reduce its physical size when needed. In certain embodiments, the robot arm provided is a versatile space-saving robot arm that can operate efficiently in compact environments, while providing both rotational and linear movements.

[0009] In certain embodiments, the robot arm provided has one or more of the following advantages:

[0010] A. Compact folding design: In certain embodiments, the robot arm provided integrates a parallelogram structure, thereby allowing it to fold into a small footprint area when not in use, thereby significantly reducing space requirements. This makes it ideal for applications in confined spaces or where portability is a priority.

[0011] B. Combined linear and rotational motion: Unlike traditional robot arms that rely solely on rotational joints, in certain embodiments, this design enables linear motion through the parallelogram linkage, thereby providing greater versatility for tasks that require both linear extension and precise rotational manipulation.

[0012] C. Modularity: In certain embodiments, the robot arm provided comprises three modular units, each with independent motors and controls, which simplifies both maintenance and customization for different tasks or environments.

[0013] D. Structural integrity with flexibility: In certain embodiments, the design ensures that while the robot arm has folding capabilities, it maintains sufficient strength and rigidity to perform heavy-duty tasks, which many foldable designs struggle to cope with. BRIEF DESCRIPTION OF DRAWINGS

[0014] FIG. 1 is a perspective view of an example robot arm according to example embodiments.

[0015] FIG. 2A shows a front view of a drive unit according to example embodiments of FIG. 1

[0016] FIG. 2B is an exploded view showing a portion of an upper portion of a drive unit according to example embodiments of FIG. 2A

[0017] FIG. 3A is a perspective view of an upper bevel gear assembly according to example embodiments of FIG. 2B

[0018] ​​​FIG. 3B It is based on FIG. 3A A perspective view of the active upper bevel gear unit in an example embodiment.

[0019] FIG. 3C It is based on FIG. 3A A front view of the active upper bevel gear unit in an example embodiment.

[0020] FIG. 3D It is based on FIG. 3A A perspective view of the passive upper bevel gear unit in an example embodiment.

[0021] FIG. 3E It is based on FIG. 3A A front view of the passive upper bevel gear unit in an example embodiment.

[0022] FIG. 4A It is based on FIG. 2A A partial view of the lower portion of the drive unit in an example embodiment, and related components and their assembly relationships.

[0023] FIG. 4B It is based on FIG. 4A A front view of the lower bevel gear assembly connected to the first drive motor in an example embodiment.

[0024] FIG. 4C It is based on FIG. 4A A perspective view of a lower bevel gear assembly connected to a first drive motor in an example embodiment.

[0025] FIG. 5A It is based on FIG. 1 A perspective view of the base unit of an example embodiment.

[0026] FIG. 5B It is based on FIG. 5A A perspective view of a base motor connected to a base motor support module, as shown in an example embodiment.

[0027] FIG. 6A It shows the drive unit 120 rotating on a DoF, according to FIG. 1 Another perspective view of an example robotic arm in an example embodiment.

[0028] FIG. 6B It is based on FIG. 2A Another front view of the drive unit in the fully retracted state in the example embodiment.

[0029] FIG. 6C It is based on FIG. 2A Another front view of the drive unit in a fully extended state in an example embodiment.

[0030] FIG. 6D It is based on FIG. 2AFigure 2 is a perspective view of a drive unit of an example embodiment of the present application in a curved state. DETAILED DESCRIPTION

[0031] DEFINITIONS

[0032] As used herein and in the claims, the term "comprising" (or any related form, such as "comprise" and "comprises"), "including" (or any related form, such as "include" or "includes"), "containing" (or any related form, such as "contain" or "contains") means including the recited elements but not excluding others. It is to be understood that for any embodiment or embodiment herein, wherein the term "comprising" (or any related form, such as "comprise" and "comprises"), "including" (or any related form, such as "include" or "includes"), or "containing" (or any related form, such as "contain" or "contains") is used, that the disclosure / application also includes alternative embodiments in which the term "comprising", "including" or "containing" is replaced by "consisting essentially of or "consisting of". These alternative embodiments using "consisting of or "consisting essentially of are understood to be less broad embodiments of the "comprising", "including" or "containing" embodiments.

[0033] As used herein and in the claims, the term "comprising" (or any related form, such as "comprise" and "comprises") "including" (or any related form, such as "include" or "includes") "containing" (or any related form, such as "contain" or "contains") means including the recited elements but not excluding other elements. It is to be understood that for any given embodiment, use of the term "comprising" (or any related form, such as "comprise" and "comprises") "including" (or any related form, such as "include" or "includes") or "containing" (or any related form, such as "contain" or "contains") in the description of a process, composition or article of manufacture, the alternative "consisting essentially of or "consisting of" can be used in place of "comprising," "including" or "containing." These alternative embodiments "consisting essentially of or "consisting of" are understood to be a more narrow embodiment of the "comprising," "including" or "containing" embodiments.

[0034] As used herein and in the claims, the singular form "a" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. When referring to ranges, the ranges are understood to include every discrete point within the range. For example, 1 to 7 is intended to mean 1, 2, 3, 4, 5, 6, and 7.

[0035] As used herein and in the claims, the term "about" is understood to be within the normal tolerances of the art and not more than ±10% of the recited value. By way of example only, about 50 means from 45 to 55, including all values therebetween. As used herein, the phrase "about" a particular value also includes the particular value, e.g., about 50 includes 50.

[0036] As used herein and in the claims, the terms "generally" or "generally" or "substantially" or "essentially" mean not required to exactly achieve the recited characteristic, angle, shape, state, structure, or value, but rather there can be tolerances, measurement error, measurement precision limitations, and other factors that would not materially affect the effect the characteristic was intended to provide. For example, an object having a "generally" cylindrical shape means that the object has a precise cylindrical shape or nearly a precise cylindrical shape. In another example, an object that is "substantially" perpendicular to a surface means that the object is precisely perpendicular to the surface or nearly precisely perpendicular to the surface, e.g., with a 5% deviation.

[0037] It should be understood that terms such as "left," "right," "up," "down," "top," "bottom," "middle," "side," "bottom," "length," "inner," "outer," "interior," "exterior," "outwardly," "inwardly," and the like as can be used herein, merely describe points of reference and do not limit the present application to any particular orientation or configuration.

[0038] Further, terms such as "first," "second," "third," and the like, merely identify one of multiple parts, components, and / or points of reference, and likewise do not limit the present application to any particular configuration or orientation.

[0039] As used herein, "connecting," "connect," and "connected" mean directly or indirectly joined or linked to other elements. In some examples, these terms mean (directly or indirectly) physically joined or linked to other elements.

[0040] As used herein and in the claims, the term "operatively connected" or "is operatively connected" means a functional or operative connection between two components or systems, allowing the components or systems to work together or interact with each other. Such a connection can be direct or indirect, and can be physical, functional, and / or electronic.

[0041] As used herein and in the claims, the term "movable" means having the ability to move, e.g., having the ability to change position.

[0042] As used herein and in the claims, the terms“robotic arm” and“arm” are used interchangeably and refer to a robotic arm that includes one or more segments connected by joints that are capable of performing specific movements and provide at least one degree of freedom (DoF). In some examples, the robotic arm is configured to manipulate an end effector, such as a robotic hand, for interacting with one or more target objects or performing functions in various applications, such as industrial, medical, or service environments. In some examples, the robotic arm performs rotational and / or translational movements.

[0043] As used herein and in the claims, the term“motor” refers to a device or component that converts electrical, hydraulic, or pneumatic energy into mechanical energy, such as producing rotational or linear motion. In some examples, the motor is configured to drive a shaft or other mechanical component within a system, thereby enabling motion and power transfer to perform specific tasks.

[0044] As used herein and in the claims, the term“proximal” refers to a segment or portion that is closer to an end effector with respect to the mechanical connection along the structure of a robotic arm.

[0045] As used herein and in the claims, the term“distal” refers to a segment or portion that is further from an end effector with respect to the mechanical connection along the structure of a robotic arm.

[0046] As used herein and in the claims, the terms“articulation,”“articulated,” and“articulately” refer to a configuration in which mechanical components are connected or linked in a manner that allows for relative movement, such as rotation, bending, or pivoting, between the mechanical components. This involves a mechanical joint or linkage that enables controlled and purposeful motion within a system.

[0047] As used herein and in the claims, the term“first central axis” refers to a straight line that extends in the longitudinal direction of the main shaft, passing through its geometric center along substantially its entire length.

[0048] As used herein and in the claims, the term“second central axis” refers to a straight line connecting the geometric centers of the execution unit base and the drive unit base.

[0049] As used herein and in the claims, the term “quadrilateral linkage” refers to a mechanical linkage system containing four links or members arranged to form a closed quadrilateral structure that enables controlled movement and force transmission between the links or members, thereby allowing specific relative motion of connected components. In some examples, the four interconnected links or members are hingedly connected to one another. In some examples, the four links or members are substantially the same length and are arranged in the form of a parallelogram. In other examples, the four links can have different lengths. For example, the four links can be two pairs of adjacent equal-length links forming a harp shape, where one pair of links can (or can not) have a different length than the other pair. In some examples, multiple quadrilateral linkages are operatively connected to one another in series or in other arrangements. In some examples, the links or members are cranks or contain cranks.

[0050] As used herein and in the claims, the term “retracted state” refers to a configuration of a quadrilateral linkage in which the links or members are retracted from one another such that the effector unit base is disposed closer to the drive unit base along the second central axis. The two joints connecting the links or members are disposed further apart from one another on opposite sides of the second central axis. The links or members are arranged to decrease the distance of an end effector connected to the effector unit base from a base unit connected to the drive unit base, thereby facilitating efficient storage or reduced operating reach. For clarity, a quadrilateral linkage can have various (or continuous) retracted states of different degrees of retraction. In some examples, the connected links or members are retracted to their closest functional position to form a “fully retracted state”.

[0051] As used herein and in the claims, the term “extended state” refers to a configuration of a quadrilateral linkage in which the links or members are extended from one another such that the effector unit base is disposed away from the drive unit base. The two joints connecting the links or members are disposed closer to one another on opposite sides of the second central axis. The links or members are arranged to increase the distance of an end effector connected to the effector unit base from a base unit connected to the drive unit base, thereby facilitating performance of tasks requiring longer reach. For clarity, a quadrilateral linkage can have various (or continuous) extended states of different degrees of extension. In some examples, the connected links or members are extended to their farthest functional position to form a “fully extended state”.

[0052] As used herein and in the claims, the term "bent state" refers to a configuration of the quadrilateral linkage in which the links or members are pre-positioned in a fully extended state in which two joints between the extended links are engaged with each other enabling a relative rotational movement of an upper pair of links or members (above the engaged joints) with respect to a lower pair of links or members (around the engaged joints). In the bent state, the two engaged joints operate simultaneously on the same side of the second central axis. This enables a controlled angular adjustment between the two sets of links or members while maintaining the structural integrity of the mechanism. For the sake of clarity, the quadrilateral linkage can have various (or continuous) bent states with different degrees of bending.

[0053] As used herein and in the claims, the terms "vertical" and "vertically" refer to a configuration in a direction parallel to the second central axis.

[0054] As used herein and in the claims, the terms "horizontal" and "horizontally" refer to a configuration in a direction perpendicular to the second central axis.

[0055] As used herein and in the claims, the term "active" refers to a component or element that requires a direct, external source of power to perform its intended function or actively generates, initiates, or controls movement within the system. In some examples, an active component is capable of interacting with other parts of the mechanism such as through electrical, hydraulic, and / or mechanical inputs.

[0056] As used herein and in the claims, the term "passive" refers to a component or element that does not require a direct, external source of power to function and is typically responsive to an external force or action without actively generating movement or control. In some examples, a passive component provides structural support, guidance, or response to a force initiated by one or more active components.

[0057] While the description makes reference to particular embodiments, the disclosure should not be construed as limited to the embodiments set forth herein.

[0058] In some embodiments, a modular robotic arm is provided, which consists of or contains three different modules: a base module, a drive module, and an execution module. Each module provides at least one degree of freedom (DoF). The base module contains a motor that drives a primary rotational joint, which serves as the foundation for the motion of the robotic arm. Connected to this base module, in some embodiments, is a set of four parallel links, which are configured in a parallelogram form as the drive module. These links provide both structural integrity and flexibility of movement. The execution module operatively connects the drive module with an end effector for actuation.

[0059] In some embodiments, each module is connected in series to the next, enabling independent motion and contributing to the overall dexterity of the robotic arm. In some embodiments, the design incorporates two motors within the drive module. One motor is located at a specific joint of the parallelogram to control the linear motion of the link, facilitating both extension and folding. The other motor is mounted at an adjacent joint to enable rotation of the link when fully extended.

[0060] In some embodiments, the provided robotic arm and system involves a combination of serial robotic arm mechanics with a unique parallelogram linkage that provides additional linear and folding capabilities. In some embodiments, the parallelogram or parallelogram structure enables the robotic arm to collapse into a compact form while extending to perform tasks that require a longer reach.

[0061] In some embodiments, the use of linear motion driven by one of the motors allows the arm to fold and extend as needed. The folding mechanism enables the arm to minimize its footprint when not in use or when operating in constrained spaces. In some embodiments, the other motor provides rotational movement around the key joint, ensuring that the arm can rotate and allowing the end effector to manipulate objects with high precision.

[0062] In some embodiments, the following method is involved:

[0063] A. Base motor control: In some embodiments, the base motor enables the entire arm to rotate around its axis, providing a base rotational degree of freedom.

[0064] B. Linear motion actuation: In some embodiments, a dedicated motor located at one of the joints of the parallelogram link mechanism drives linear motion. This enables the link to extend or fold in a smooth, controlled manner.

[0065] C. Rotational motion of the link: In some embodiments, a second motor placed at an adjacent joint allows the four links to rotate around this joint when they are fully extended. This feature allows the performance of tasks that require a combination of linear extension and rotational manipulation.

[0066] In some embodiments, this configuration provides a highly adaptive robotic arm that can perform traditional tasks such as object manipulation and positioning, as well as unique tasks involving linear extension, folding, and compact storage.

[0067] In some embodiments, the provided robotic arm and system have one or more of the following technical features and functional advantages:

[0068] A. Parallelogram-based folding mechanism:

[0069] Technical difference: When compared to traditional serial or parallel robot arms that rely solely on rotational joints or complex linkage systems, in some embodiments the provided robot arms and systems utilize parallelogram or quadrilateral link structures containing four links. This enables smooth, controlled linear extension and folding of the arm.

[0070] Functional advantage: In some embodiments, the arm can be folded into a compact form, making it highly space-efficient while retaining the ability for linear extension. This feature enables the arm to operate in both confined spaces and larger workspaces, a functionality that traditional robot arms cannot simultaneously achieve.

[0071] B. Linear motion capability:

[0072] Technical difference: When compared to most traditional arms that focus on rotational motion across joints with little to no linear motion capability, in certain embodiments the provided robot arms and systems integrate a motor-driven linear motion mechanism through one of the joints of the quadrilateral link mechanism.

[0073] Functional advantage: The ability to perform linear extension allows the arm to reach straight into tight spaces or dynamically extend its reach, which is particularly useful in assembly lines, inspection tasks, or operations where linear accuracy is necessary. Traditional arms lack this level of versatility.

[0074] C. Dual actuation in parallelogram:

[0075] Technical difference: In some embodiments, the provided robot arms and systems utilize two motors at adjacent joints of the quadrilateral link mechanism: one motor for controlling linear motion (folding and extension), and another motor for enabling rotational movement of the extension link. This dual actuation system does not exist in conventional serial or foldable robot arm designs.

[0076] Functional advantage: In some embodiments, this design enables both precise rotational manipulation and the ability to transition seamlessly between folded and extended states without sacrificing strength or stability during operation. Traditional foldable designs often compromise linear or rotational capabilities.

[0077] D. Modularity:

[0078] Technical difference: In some embodiments, the provided robot arms contain three modular units that individually have their own DoF, enabling flexible and independent control. This modular design is different from both traditional serial robot arms and foldable arms, which typically lack this modularity.

[0079] Functional advantages: In some embodiments, modularity enhances ease of maintenance and the ability to configure the robotic arm for different applications. It also enables replacement or upgrading of individual modules, providing greater customization and reducing downtime. Conventional designs typically require replacement or repair of the entire arm when a single component fails.

[0080] E. Compact and efficient design:

[0081] Technical differences: While some conventional arms attempt to minimize size, in some embodiments, the provided robotic arm and system balance compactness (when folded) and functionality of extension, and outperform conventional arms in both compact storage and functional range, making it suitable for mobile robots, portable systems, or environments with limited space. Conventional designs sacrifice size for functionality or require more complex systems to achieve similar results.

[0082] In summary, in some embodiments, the present utility is technically different due to the use of parallelogram linkage systems or quadrilateral linkages, dual-motor driven actuation, and modular construction. Functionally, the provided robotic arm and system outperform conventional arms by combining linear extension, rotational manipulation, and compact folding into a single, efficient design.

[0083] Numbered embodiments

[0084] Embodiment 1. A robotic arm comprising a base unit and a drive unit operatively connected to each other, wherein the base unit comprises: a base motor operatively connected to the drive unit and configured to drive the drive unit to move in at least one degree of freedom; and a base configured to support the base motor and the drive unit, and wherein the drive unit comprises: a quadrilateral linkage; a first drive motor operatively connected to the quadrilateral linkage and configured to drive the quadrilateral linkage switchable between at least a retracted state and an extended state; and a second drive motor operatively connected to the quadrilateral linkage and configured to drive the quadrilateral linkage switchable from at least the extended state to a curved state.

[0085] Example 2. The robotic arm of Example 1, wherein the quadrilateral linkage comprises: an execution unit base for connection with an end effector; a drive unit base for connection with the base unit; a pair of upper cranks and a pair of lower cranks, each of which comprises a proximal portion and a distal portion; an upper bevel gear assembly; a lower bevel gear assembly; a first shaft and a second shaft, wherein the upper bevel gear assembly operatively connects the proximal portions of the pair of upper cranks with the execution unit base, wherein the lower bevel gear assembly operatively connects the distal portions of the pair of lower cranks with the drive unit base, and wherein the first shaft and the second shaft hingedly connect the distal portions of the pair of upper cranks with the proximal portions of the pair of lower cranks to form first and second joints, respectively, such that a hinged quadrilateral linkage is formed.

[0086] Example 3. The robotic arm of Example 2, wherein, in the extended state, the first joint is engaged with the second joint to form a hinged joint such that the pair of upper cranks is rotatable relative to the pair of lower cranks about the hinged joint, thereby switching to the flexed state.

[0087] Example 4. The robotic arm of any one of Examples 2-3, wherein the second drive motor is operatively connected with the first joint via the first shaft.

[0088] Example 5. The robotic arm of any one of Examples 2-4, wherein the first joint further comprises a clutch unit that reversibly engages and disengages the second drive motor with the first shaft in the extended state.

[0089] Example 6. The robotic arm of any one of Examples 2-5, wherein the second joint is a passive joint and further comprises a joint bearing unit for supporting the second shaft to maintain a center position thereof.

[0090] Example 7. The robotic arm of any one of Examples 2-6, wherein the upper bevel gear assembly comprises: a pair of active upper bevel gear units that are respectively driven by the pair of upper cranks; and a pair of passive upper bevel gear units that are engaged with the pair of active upper bevel gear units and connected with the execution unit base, such that motion of the pair of upper cranks is translated into motion of the execution unit base.

[0091] Example 8. The robotic arm of Example 7, wherein the upper bevel gear assembly further comprises: a pair of active upper shafts that transmit movement of the pair of upper cranks to movement of the pair of active upper bevel gear units; and a pair of passive upper shafts connected to the pair of passive upper bevel gear units.

[0092] Example 9. The robotic arm of any of Examples 8, wherein the upper bevel gear assembly further comprises a pair of active upper bearing housings and a pair of passive upper bearing housings connected to the execution unit base and supporting the pair of active upper shafts and the pair of passive upper shafts, respectively, to maintain central positions thereof.

[0093] Example 10. The robotic arm of any of Examples 8-9, wherein the upper bevel gear assembly further comprises a pair of upper locking nuts configured to limit axial movement of the pair of passive upper shafts.

[0094] Example 11. The robotic arm of any of Examples 2-10, wherein the lower bevel gear assembly comprises: an active lower bevel gear unit driven by the first drive motor; and a pair of passive lower bevel gear units engaged with the active lower bevel gear unit and connected with distal portions of the pair of lower cranks, respectively, such that movement from the first drive motor is translated to movement of the pair of lower cranks.

[0095] Example 12. The robotic arm of Example 11, wherein the lower bevel gear assembly further comprises a pair of passive lower shafts connected with distal portions of the pair of lower cranks, respectively.

[0096] Example 13. The robotic arm of any of Examples 12, wherein the lower bevel gear assembly further comprises a pair of lower bearing housings connected with the drive unit base and supporting the pair of passive lower shafts to maintain central positions thereof.

[0097] Example 14. The robotic arm of any of Examples 12-13, wherein the lower bevel gear assembly further comprises a pair of lower locking nuts configured to limit axial movement of the pair of passive lower shafts, respectively.

[0098] Example 15. The robotic arm of any of Examples 2-14, wherein the lower bevel gear assembly further comprises one or more support limit blocks configured to limit a range of downward movement of the drive unit to prevent damage to the robotic arm.

[0099] Example 16. The robotic arm of any of Examples 2-15, wherein the base motor is connected with the drive unit base via a spindle such that rotation of the base motor is transferred to movement of the drive unit.

[0100] Example 17. A robotic arm for an end effector, the robotic arm comprising a base unit and a drive unit operatively connected with each other, wherein the base unit comprises: a base motor operatively connected with the drive unit and configured to drive the drive unit to rotate about a central axis thereof; and a base configured to support the base motor and the drive unit, wherein the drive unit comprises: a quadrilateral linkage; a first drive motor operatively connected with the quadrilateral linkage and configured to drive the quadrilateral linkage switchable between at least a retracted state and an extended state; and a second drive motor operatively connected with the quadrilateral linkage and configured to drive the quadrilateral linkage switchable from at least the extended state to a curved state, wherein the quadrilateral linkage comprises: an execution unit base for connection with the end effector; a drive unit base for connection with the base unit; a pair of upper cranks and a pair of lower cranks, each comprising a proximal portion and a distal portion; an upper bevel gear assembly; a lower bevel gear assembly; a first shaft and a second shaft, wherein the upper bevel gear assembly operatively connects the proximal portions of the pair of upper cranks with the execution unit base, wherein the lower bevel gear assembly operatively connects the distal portions of the pair of lower cranks with the drive unit base, wherein the first shaft and the second shaft hingedly connect the distal portions of the pair of upper cranks with the proximal portions of the pair of lower cranks to form first and second joints, respectively, such that a hinged quadrilateral linkage is formed, and wherein in the extended state, the first joint is engaged with the second joint to form a hinged joint such that the pair of upper cranks is rotatable relative to the pair of lower cranks about the hinged joint, thereby switching to the curved state.

[0101] Example 18. A robotic system comprising: one or more robotic arms of Examples 1-17; and one or more end effectors, wherein the robotic arms and the end effectors are operatively connected with each other.

[0102] Example 19. The robotic system of Example 18, wherein the end effector is a robotic hand.

[0103] Examples

[0104] Examples are provided herein that describe certain embodiments of the disclosure in more detail. The examples provided herein are for illustrative purposes only and are not meant to limit the scope of the application in any way. All references given below and elsewhere in this application are hereby incorporated by reference into this document.

[0105] Robot arm

[0106] FIG. 1 to FIG. 6D An example robot arm 100 and its components are shown. FIG. 1 A perspective view of an example robot arm 100 is shown, which generally contains a base unit 110 and a drive unit 120. The base unit 110 comprises a base motor 111, a base 112 and a spindle unit 113. A first central axis x, indicated in dashed lines, extends in the longitudinal direction of the spindle 1130, thereby passing through its geometric center along its entire length. The base motor 111 is configured to drive the drive unit 120 via the spindle unit 113, which translates the rotational motion of the base motor 111 substantially around the first central axis x to the drive unit 120. In this example, the base motor 111 is a HO7213 servo motor (Tonifishi). The base 112 is a support body for the overall support and mounting of the example robot arm 100.

[0107] Still referring to FIG. 1 , the drive unit 120 generally contains a quadrilateral linkage 121, a first drive motor 122 and a second drive motor 123, all of which will be described in more detail later.

[0108] Still referring to FIG. 1 , the quadrilateral linkage 121 contains a drive unit base 1210, an execution unit base 1211, a first joint 1218 and a second joint 1219. The drive unit base 1210 is connected on the lower side to the spindle unit 113 and on the opposite upper side to the quadrilateral linkage 121, thereby transmitting rotational motion from the spindle unit 113 to the drive unit 120. The execution unit base 1211 is configured to connect and directly or indirectly support one or more components of an execution unit mounted thereon. In some examples, the one or more components of the execution unit is one or more end effectors, such as a robot hand. In some examples, the robot system contains more than one robot arm 100, such that multiple robot arms 100 can be modularly connected to each other (e.g., one after the other) to form a complex robot arm.

[0109] Still referring to FIG. 1The first drive motor 122 is operatively connected to and drives the lower portion of the quadrilateral linkage 121 (i.e., the portion of the quadrilateral linkage 121 below the first joint 1219 and the second joint 1219), allowing the quadrilateral linkage 121 to switch between different retracted and extended states. In this example, the first drive motor 122 is a Maita X6-40 motor (Suzhou Micro Actuator Technology Co., Ltd.).

[0110] Still referencing FIG. 1 The second drive motor 123 is connected to the first joint 1218, thereby driving the upper portion of the quadrilateral linkage 121 (i.e., the portion of the quadrilateral linkage 121 above and including the first and second joints 1218 and 1219), allowing the quadrilateral linkage 121 to switch between different bending states. In this example, the second drive motor 123 is a Maita X4-24 motor (Suzhou Micro Actuator Technology Co., Ltd.).

[0111] drive unit

[0112] FIG. 2A to FIG. 2B The drive unit 120 and its components are shown. (Reference) FIG. 1 and FIG. 2AThe drive unit 120 generally includes a four-bar linkage 121, a first drive motor 122, and a second drive motor 123. The four-bar linkage 121 includes an effector unit base 1211, a drive unit base 1210, a pair of upper cranks 1213a and 1213b, a pair of lower cranks 1214a and 1214b, an upper bevel gear assembly 1212, a lower bevel gear assembly 1215, a first shaft 1216, and a second shaft 1217. Each of the pair of upper cranks 1213a and 1213b and the pair of lower cranks 1214a and 1214b has a proximal portion and a distal portion. The upper bevel gear assembly 1212 operatively connects the proximal portions of the pair of upper cranks 1213a and 1213b with the effector unit base 1211, thereby translating movement of the upper cranks 1213a and 1213b into movement of the effector unit base 1211. The lower bevel gear assembly 1215 operatively connects the distal portions of the pair of lower cranks 1214a and 1214b with the drive unit base 1210 and the first drive motor 122, thereby translating movement of the first drive motor 122 into movement of the lower cranks 1214a and 1214b. The first shaft 1216 hingedly connects the distal portion of the upper crank 1213a with the proximal portion of the lower crank 1214a and the second drive motor 123 to form a first joint 1218. The second shaft 1217 hingedly connects the distal portion of the upper crank 1213b with the proximal portion of the lower crank 1214b to form a second joint 1219. Briefly stated, the four cranks 1213a, 1213b, 1214a, and 1214b are hingedly connected by the two bevel gear assemblies 1212 and 1215 and the two joints 1218 and 1219, such that a hinged four-bar linkage is formed.

[0113] Still referring to FIG. 2A The second central axis x' shown in dashed line extends in the longitudinal direction of the line connecting the geometric centers of the effector unit base 1211 and the drive unit base 1210.

[0114] FIG. 2B An exploded view showing a portion of the upper portion of the drive unit 120 and the relevant components and their assembly relationship is shown. Referring to FIG. 2A and FIG. 2B The upper crank 1213a is an elongated body that includes a proximal shaft-receiving hole 12131a, a ring-shaped distal connector 12132a, and two intermediate slots 12133a. The upper crank 1213b is an elongated body that includes a proximal shaft-receiving hole, a distal shaft-receiving hole 12132b, and two intermediate slots 12133b, where the distal shaft-receiving hole 12132b includes a joint bearing 12191.

[0115] Still referring to FIG. 2B, the lower crank 1214a is an elongated body containing a distal strap portion 12145a and a proximal curved portion 12146a, wherein the distal strap portion 12145a contains a distal portion of the lower crank 1214a containing a distal shaft receiving hole 12142a and a strap-shaped intermediate slot 12143a, and wherein the proximal curved portion 12146a extends upwardly from the distal strap portion 12145a and contains a proximal portion of the lower crank 1214a and a curved intermediate slot 12144a. The proximal portion of the lower crank 1214a further contains the first shaft 1216, a first shaft locking nut 12161 and a clutch unit 12181.

[0116] Still referring to FIG. 2B , the lower crank 1214b is an elongated body containing a distal strap portion 12145b and a proximal curved portion 12146b, wherein the distal strap portion 12145b contains a distal portion of the lower crank 1214b containing a distal shaft receiving hole 12142b and a strap-shaped intermediate slot 12143b, and wherein the proximal curved portion 12146b extends upwardly from the distal strap portion 12145b and contains a proximal portion of the lower crank 1214b and a curved intermediate slot 12144b. The proximal portion of the lower crank 1214b further contains the second shaft 1217.

[0117] Still referring to FIG. 2B , in this example, the intermediate slots 12133a, 12133b, 12145a, 12145b, 12146a, 12146b are holes or grooves provided on the body of the cranks to reduce the weight of the cranks without compromising their structural integrity.

[0118] Still referring to FIG. 2B , the distal connector 12132a of the upper crank 1213a is sized and shaped to be connected on its inner side to the second drive motor 123 and on its opposite outer side to the clutch unit 12181, wherein the clutch unit 12181 is further connected on its outer side to the proximal portion of the lower crank 1214a, and the first shaft 1216 is connected to the proximal end of the lower crank 1214a with one end axially limited by the first shaft locking nut 12161, and to the second drive motor 123 with the opposite end via the clutch unit 12181, which switchably and / or reversibly engages and disengages the second drive motor 123 with the first shaft 1216 for the purpose of motion state switching, thereby connecting the upper crank 1213a and the lower crank 1214a by forming the first joint 1218.

[0119] Still referring to FIG. 2BThe second shaft 1217 is connected at one end to the proximal portion of the lower crank 1214b and at the other opposite end to the joint bearing 12191 of the upper crank 1213b, wherein the joint bearing 12191 maintains the central position of the second shaft 1217, thereby connecting the upper crank 1213b with the lower crank 1214b by forming a second joint 1219.

[0120] Still referring to FIG. 2B The proximal shaft receiving holes of the pair of upper cranks 1213a and 1213b are sized and shaped to mate with and operatively connect with the upper bevel gear assembly 1212, which is further connected with the effector unit base 1211, thereby translating the motion of the pair of upper cranks 1213a and 1213b into the motion of the effector unit base 1211.

[0121] The upper bevel gear assembly

[0122] FIG. 3A to FIG. 3E An example upper bevel gear assembly 1212 and its components are shown. With respect to FIG. 1 And with respect to FIG. 3A to FIG. 3E The upper bevel gear assembly 1212 generally contains a pair of driving upper bevel gear units 12121, a pair of passive upper bevel gear units 12122. Each driving upper bevel gear unit 12121 generally contains a driving upper bevel head 12128, a driving upper bearing unit 12123 having a driving upper bearing unit housing configured to fixedly connect with the effector unit base, and a driving upper shaft 12125 sized and shaped to engage with the driving upper bevel head 12128 and the driving upper bearing unit 12121 such that rotation of the driving upper shaft 12125 drives rotation of the driving upper bevel head 12128. The driving upper bevel head 12128 generally contains a truncated conical head portion having an inclined smooth surface having a pitch angle of about 45 degrees.

[0123] Similarly, each passive upper bevel gear unit 12122 generally contains a passive upper bevel head 12129, a passive upper bearing unit 12124 having a passive bearing unit housing fixedly connected with the performance unit base, and a passive upper shaft 12126 sized and shaped to engage the passive upper bevel head 12129 and the passive upper bearing unit 12123 such that rotation of the passive upper bevel head 12129 drives rotation of the passive upper shaft 12126. The passive upper bevel gear head 12129 generally contains a truncated conical head portion having a sloped smooth surface having an approximately 45 degree pitch angle. In this example, the passive upper bevel gear unit 12122 further contains an upper locking nut 12127 configured to limit axial movement of the passive upper shaft 12126.

[0124] In this example, the pair of active upper bevel gear units 12121 and the pair of passive upper bevel gear units 12122 are arranged such that the active / passive bevel heads face each other with the truncated conical head portions in direct frictional contact with each other. The bevel heads of the pair of active upper bevel gear units 12121 and the pair of passive upper bevel gear units 12122 are generally identical in size and shape, each having an approximately 45 degree pitch angle such that the shaft angle between adjacent active and passive upper shafts is approximately 90 degrees. The pair of active upper bevel gear units 12121 are configured to rotate in opposite directions to drive the pair of active upper bevel gear units 12121 to rotate in synchrony. Angular motion of the upper cranks 1213a and 1213b is thus translated into linear motion of the performance unit base via the upper bevel gear assembly 1212.

[0125] Lower bevel gear assembly

[0126] FIG. 4A A partial top view showing portions of the lower portion of the drive unit 120 and relevant components and their assembly relationship are shown. FIG. 4B to FIG. 4C A side view and a perspective view of the lower bevel gear assembly are shown, respectively. Referring now to FIG. 4A The lower bevel gear assembly 1215 generally contains an active lower bevel gear unit 12151 operatively connected with and driven by the first drive motor 122, and a pair of passive lower bevel gear units 12152 operatively connected with the distal portions of the pair of lower cranks 1214a and 1214b. The lower bevel gear assembly 1215 is fixedly connected with and supported by the drive unit base 1210.

[0127] Referring now to FIG. 4B to FIG. 4CThe lower bevel gear assembly 1215 generally contains a driving lower bevel gear unit 12151 and a pair of passive lower bevel gear units 12152. The driving lower bevel gear unit 12151 generally contains a driving lower bevel head 12158 and a driving lower shaft 12155 sized and shaped to engage the driving lower bevel head 12158 such that rotation of the driving lower shaft 12155 drives rotation of the driving lower bevel head 12158. The driving lower bevel head 12158 generally contains a frusto-conical head portion having an inclined smooth surface having an approximately 45 degree pitch angle.

[0128] Similarly, each passive lower bevel gear unit 12152 generally contains a passive lower bevel head 12159, a passive lower bearing unit 12154 having a passive bearing unit housing to fixedly connect with the drive unit base 1210, and a passive lower shaft 12153 sized and shaped to engage the passive lower bevel head 12159 and the passive lower bearing unit 12154 such that rotation of the passive upper bevel head 12129 drives rotation of the passive lower shaft 12153. The passive lower bevel head 12129 generally contains a frusto-conical head portion having an inclined smooth surface having an approximately 45 degree pitch angle. In this example, the passive upper bevel gear unit 12152 further contains a lower locking nut 12157 configured to limit axial movement of the passive lower shaft 12126 and secure the lower crank 1214a or 1214b to the outer end of the lower shaft 12126.

[0129] Referring now to FIG. 4C In this example, the lower bevel gear assembly 1215 further contains a first motor mounting bracket 12157 configured to fixedly connect a first drive motor 122 to the lower bevel gear assembly 1215. In this example, the lower bevel gear assembly 1215 further contains a pair of L-shaped support stop blocks 12156 disposed on the top of the pair of lower bearing housings and configured to limit the downward movement range of the upper cranks of the drive unit 120 to prevent damage to the robotic arm 100.

[0130] Referring now to FIG. 4A to FIG. 4CThe pair of driven lower bevel gear units 12152 and the pair of driven upper bevel gear units 12151 are arranged such that the driving / driven bevel heads face each other in direct frictional contact with each other. The bevel heads of the pair of driven lower bevel gear units 12152 and the pair of driven upper bevel gear units 12151 are substantially identical in size and shape, each having a pitch angle of about 45 degrees, such that the shaft angle between adjacent driving lower shafts and driven lower shafts is about 90 degrees. The driven lower bevel gear units 12152 are configured to rotate to drive the pair of driven upper bevel gear units 12151 to rotate in unison. The driven lower bevel gear units 12152 are operatively connected with and driven by the first drive motor 122 via the pair of driven lower shafts 12153. The pair of driven upper bevel gear units 12151 are engaged with the driven lower bevel gear units 12152 and connected with the pair of upper cranks 1213a and 1213b via the pair of driven upper shafts 12154, such that the rotational motion from the first drive motor 122 is translated into angular motion of the pair of upper cranks 1213a and 1213b via the upper bevel gear assembly 1216.

[0131] Base unit

[0132] FIG. 5A to FIG. 5B An example base unit 110 and its components are shown. Referring to FIG. 5A The base unit 110 generally contains a base motor 111, a base 112, and a spindle 113. In this example, the base 112 generally contains a base plate 1123, a motor support frame 1121, and four support legs 1122. The motor support frame 1121 is fixedly connected with the base plate 1123 on the underside and is configured to house the base motor 111 therein. The four support legs 1122 (each containing a horizontal foot portion for being fixed to or connected with a base plate and a vertical elongated leg portion that is longer in length than the motor support frame 1121 and is fixedly connected with the underside of the base plate 1123 proximate to its four corner edges) provide sufficient space to hold the base motor support frame 1121 and the base motor 111 disposed therein to ensure the stability of the overall structure. Each of the leg portions of the four support legs further contains a slot to reduce the weight of the support legs without compromising their structural integrity. The motor is positioned below the base plate 1123 and is generally aligned with the geometric center of the base 112. Referring to FIG. 5A to FIG. 5BThe spindle unit 113 comprises a spindle 1130 extending through the base 112 with an upper end operatively connected to the drive unit mounted above the base 112 and an opposite lower end operatively connected to a transmission disc 1132 for transmitting rotational motion from the base motor 111 across the base 112 to the drive unit. The one or more washers 1131 reduce spindle vibrations and act as a limiting element for the spindle 1130.

[0133] Reference is now made to FIG. 5B In this example, the base motor support frame 1121 comprises a horizontal motor support floor and two curved support walls defining a space for accommodating the base motor 111 therein. The base motor 111 is fixedly connected to and supported by the motor support floor. The base motor 111 is configured to drive the drive unit via the spindle unit 113 which translates rotational motion of the base motor 111 substantially about the first central axis x to the drive unit. The spindle 1130 is operatively connected to the base motor 111 via the transmission disc 1132 which transmits rotational motion of the base motor 111 to the spindle 113.

[0134] Motion of the robot arm

[0135] FIG. 6A to FIG. 6D Examples of different motions of the robot arm 100 are illustrated, including rotational motion of the drive unit 120, motion of the drive unit 120 in a retracted state, an extended state, a curved state, respectively.

[0136] FIG. 6A An example rotational motion of the drive unit 120 is illustrated. Reference is now made to FIG. 1 Reference is now made to FIG. 6A In this example, the drive unit base 1210 supports the drive unit 120 mounted thereon and is operatively connected to the base motor 111 via the spindle unit 113 of the base unit 110 such that the first central axis x is substantially aligned with the second central axis x’. The base motor 111 is configured to provide rotational motion which is transmitted to the drive unit base 1210 and thus to the drive unit 120 about the first / second central axis x / x’ via the spindle unit 113, enabling the drive unit 120 to actuate in one degree of freedom. In this example, the drive unit 120 is in a partially retracted / extended state. It will be appreciated that the rotational motion can operate in any retracted and / or extended state, including a curved state.

[0137] Reference is now made to FIG. 6BThe drive unit 120 is in a fully retracted state, wherein the distance between the execution unit base 1211 and the drive unit base 1210 is minimized to a distance corresponding to the limit by which the support limit block 12156 forces the drive unit 120 to move downward along the second central axis x'.

[0138] Now about FIG. 1 and FIG. 2B And reference FIG. 6B In the fully retracted state, the pair of upper cranks 1213a and 1213b are positioned on opposite sides relative to the second central axis x', reaching their maximum horizontal distance, as are the pair of lower cranks 1214a and 1214b. The first joint 1218 and the second joint 1219 are disengaged from each other. The clutch unit 12181 of the first joint 1218 also disengages the connection between the second drive motor 123 and the first shaft 1216.

[0139] Now for reference FIG. 6C The drive unit 120 is in a fully extended state, wherein the distance between the actuator base 1211 and the drive unit base 1210 is maximized to allow the actuator base 1211 to be set away from the drive unit base 1210 along the second central axis x'.

[0140] Now about FIG. 1 and FIG. 2B And reference FIG. 6C In the fully extended state, the pair of upper cranks 1213a and 1213b, the first joint 1218, and the second joint 1219 are all substantially aligned with the second central axis x'. The clutch unit 12181 of the first joint 1218 reversibly and / or switchably engages and disengages the connection between the second drive motor 123 and the first shaft 1216, allowing the quadrilateral linkage 121 to switch from a fully extended state to one of a bent state, and vice versa.

[0141] Now about FIG. 1 and FIG. 2B And reference FIG. 6A to FIG. 6CIn the retracted state or the extended state, the first drive motor 122 drives the quadrilateral linkage 121 to switch between the different states, while the second drive motor 123 is disengaged from the first shaft 1216, thereby causing disengagement between the first joint 1218 and the second joint 1219. The lower bevel gear assembly 1215 translates the motion of the first drive motor 122 into the motion of the pair of lower cranks 1214a and 1214b, which simultaneously actuate the motion of the pair of upper cranks 1213a and 1213b connected thereto via the first joint 1218 and the second joint 1219. The upper bevel gear assembly 1212 further translates the motion of the pair of upper cranks 1213a and 1213b into the motion of the execution unit base 1211.

[0142] FIG. 6D An example is shown in which the drive unit 120 is in the curved state. Now with respect to FIG. 2B And with reference to FIG. 6D , the first joint 1218 and the second joint 1219 simultaneously operate on the same side relative to the second central axis x' and engage to form the articulated joint 12189, in which the clutch unit 12181 of the first joint 1218 engages the second drive motor 123 with the first shaft 1216, such that the first joint 1218 becomes an active joint driven by the second drive motor 123 via the first shaft 1216, and the second joint 1219 becomes a passive joint driven by the first joint 1218, thereby allowing the rotational motion of the pair of upper cranks 1213a and 1213b relative to the pair of lower cranks 1214a and 1214b, and enabling controlled angular adjustment between the two pairs of cranks by the second drive motor 123, while maintaining the structural integrity of the overall structure.

[0143] Now with reference to FIG. 6A to FIG. 6D , the robotic arm 100 is configured to perform complex motions by simultaneously or consecutively combining rotational motion with the motion of the drive unit 120 in the (partially or fully) retracted state, the extended state, and the curved state.

[0144] The exemplary embodiments of the present application have thus been described. Although the description refers to particular embodiments, it will be clear to a person skilled in the art that the present application can be practiced by variations of these specific details. The present application should not be interpreted as being limited to the embodiments set forth herein.

[0145] For example, in certain examples, the base motor provides rotational drive motion to the drive unit in one DoF. In other examples, other types of base motors and additional components can be provided instead, such that the drive unit 120 is connected to the base unit 110 in a manner such that the second central axis x' can or can not be aligned with the first central axis x. This misalignment can result in an angular difference between the two axes, enabling the drive unit 120 to actuate in more than one degree of freedom.

Claims

1. A robotic arm comprising: a base unit and a drive unit operatively connected to each other, wherein the base unit comprises: a base motor operatively connected to the drive unit and configured to drive the drive unit to move in at least one degree of freedom; and a base configured to support the base motor and the drive unit, wherein the drive unit comprises: a quadrilateral linkage mechanism; a first drive motor operatively connected to the quadrilateral linkage mechanism and configured to drive the quadrilateral linkage mechanism switchable between at least a retracted state and an extended state; and a second drive motor operatively connected to the quadrilateral linkage mechanism and configured to drive the quadrilateral linkage mechanism switchable from at least the extended state to at least one curved state.

2. The robotic arm of claim 1, wherein, the quadrilateral linkage mechanism comprises: an execution unit base operatively connected to an end effector; a drive unit base operatively connected to the base unit; a pair of upper cranks and a pair of lower cranks, each of which comprises a proximal portion and a distal portion; an upper bevel gear assembly; a lower bevel gear assembly; a first shaft and a second shaft, wherein the upper bevel gear assembly operatively connects the proximal portions of the pair of upper cranks with the execution unit base, wherein the lower bevel gear assembly operatively connects the distal portions of the pair of lower cranks with the drive unit base, and wherein the first shaft and the second shaft hingedly connect the distal portions of the pair of upper cranks with the proximal portions of the pair of lower cranks to form first and second joints, respectively, such that a hinged quadrilateral linkage mechanism is formed.

3. The robotic arm of claim 2, wherein, in the extended state, the first joint is engaged with the second joint to form a hinged joint such that the pair of upper cranks is rotatable relative to the pair of lower cranks about the hinged joint, thereby switching to at least one curved state.

4. The robotic arm of claim 2, wherein, the second drive motor is operatively connected to the first joint via the first shaft.

5. The robotic arm of claim 2, wherein, the first joint further comprises a clutch unit that reversibly engages and disengages the second drive motor with the first shaft in the extended state.

6. The robotic arm of claim 2, wherein, the second joint is a passive joint and further comprises a joint bearing unit for supporting the second shaft to maintain a central position thereof.

7. The robotic arm of claim 2, wherein, the upper bevel gear assembly comprises a pair of active upper bevel gear units driven by the pair of upper cranks, respectively, and a pair of passive upper bevel gear units engaged with the pair of active upper bevel gear units and connected with the execution unit base such that the motion of the pair of upper cranks is translated into the motion of the execution unit base.

8. The robotic arm of claim 7, wherein, the upper bevel gear assembly further comprises a pair of active upper shafts that transmit the motion of the pair of upper cranks to the motion of the pair of active upper bevel gear units, and a pair of passive upper shafts connected to the pair of passive upper bevel gear units.

9. The robotic arm of claim 8, wherein, The upper bevel gear assembly further includes a pair of active upper bearing housings and a pair of passive upper bearing housings connected to the execution unit base and supporting the pair of active upper shafts and the pair of passive upper shafts, respectively, to maintain their central positions.

10. The robotic arm of claim 8, wherein, The upper bevel gear assembly further includes a pair of upper locking nuts configured to limit axial movement of the pair of passive upper shafts.

11. The robotic arm of claim 2, wherein, The lower bevel gear assembly includes an active lower bevel gear unit driven by the first drive motor and a pair of passive lower bevel gear units engaged with the active lower bevel gear unit and connected with distal portions of the pair of lower cranks, respectively, such that motion from the first drive motor is translated into motion of the pair of lower cranks.

12. The robotic arm of claim 11, wherein, The lower bevel gear assembly further includes a pair of passive lower shafts connected with distal portions of the pair of lower cranks, respectively.

13. The robotic arm of claim 12, wherein, The lower bevel gear assembly further includes a pair of lower bearing housings connected with the drive unit base and supporting the pair of passive lower shafts to maintain their central positions, respectively.

14. The robotic arm of claim 12, wherein, The lower bevel gear assembly further includes a pair of lower locking nuts configured to limit axial movement of the pair of passive lower shafts, respectively.

15. The robotic arm of claim 2, wherein, The lower bevel gear assembly further includes one or more support limit blocks configured to limit a range of downward movement of the drive unit to prevent damage to the robotic arm.

16. The robotic arm of claim 2, wherein, The base motor is connected with the drive unit base via a main shaft such that rotation of the base motor is translated into motion of the drive unit.

17. A robotic arm for an end effector, the robotic arm comprising: a base unit, a drive unit, and an execution unit operatively connected with each other, wherein the base unit comprises: a base motor operatively connected with the drive unit and configured to drive the drive unit to rotate about a central axis thereof; and a base configured to support the base motor and the drive unit, wherein the drive unit comprises: a quadrilateral linkage; a first drive motor operatively connected with the quadrilateral linkage and configured to drive the quadrilateral linkage switchable between at least a retracted state and an extended state; and a second drive motor operatively connected with the quadrilateral linkage and configured to drive the quadrilateral linkage switchable from at least the extended state to at least one bent state, an execution unit base for connection with the end effector; a drive unit base for connection with the base unit; a pair of upper cranks and a pair of lower cranks, each of which comprises a proximal portion and a distal portion; an upper bevel gear assembly; a lower bevel gear assembly; a first shaft and a second shaft, and wherein the execution unit includes or is operatively connected with an execution unit base, the execution unit base being operatively connected with the drive unit and the end effector, wherein the upper bevel gear assembly operatively connects proximal portions of the pair of upper cranks with the execution unit base, wherein the lower bevel gear assembly operatively connects distal portions of the pair of lower cranks with the drive unit base, wherein the first and second shafts hingedly connect distal portions of the pair of upper cranks with proximal portions of the pair of lower cranks to form first and second joints, respectively, such that a hinged four-bar linkage is formed, and wherein in the extended state, the first joint is engaged with the second joint to form a hinged joint such that the pair of upper cranks is rotatable relative to the pair of lower cranks about the hinged joint, thereby switching to the at least one curved state.

18. A robotic system, comprising: one or more robotic arms as claimed in claim 1 or claim 17; and one or more end effectors, wherein the robotic arms and the end effectors are operatively connected with each other.

19. The robotic system of claim 18, wherein, The end effector is a robotic hand.

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