Robotic arm and joint module thereof

Abstract

A joint module for a robotic arm is provided. The joint module includes a base having a first ball ramp assembly. The first ball ramp assembly including multiple first ball ramps; a fixing ring having multiple receiving slots for accommodating multiple balls, where the multiple balls are disposed between the base and the fixing ring; a central shaft passing through the base and the fixing ring; and an elastic member disposed on one side of the fixing ring. When the central shaft drives the fixing ring to rotate, the multiple balls slide along the multiple first ball ramps, such that the fixing ring is caused to generate an axial displacement to compress the elastic member. In addition, a robotic arm using the joint module is also provided.

Description

[DESCRIPTION][Title]Robotic Arm and Joint Module Thereof[Technical Field]

[0001] The present disclosure is related to robotic technology and, more specifically, to a robotic arm and a joint module thereof.[Background Art]

[0002] Conventional robotic arms, in their design and application, often need to address balance issues caused by gravitational loads. Particularly, when a heavy object is attached to the front end of the arm, gravity may cause the arm to sag or deviate, thus requiring the operator to exert additional force to maintain its position or adjust its angle. This not only increases the operational burden but may also lead to safety hazards or mechanical structure fatigue. In the conventional arts, some robotic arm joints employ counterweight mechanisms to assist with balance. However, these methods typically fail to precisely correspond to gravitational changes at different rotational angles, resulting in either excessive or insufficient compensation forces, which affect operational accuracy and comfort.[Summary]

[0003] In view of the above, the present disclosure provides a joint module for a robotic arm and a joint module thereof, which achieves a precise weight compensation mechanism through the cooperation of a first ball ramp assembly on the base of the joint module, receiving slots of a fixing ring, rotational drive of a central shaft, and axial compression of an elastic member. When the central shaft drives the fixing ring to rotate, the balls slide along the ramps, causing the fixing ring to generate an axial displacement that compresses the elastic member. The force exerted by the compressed elastic member on the fixing ring is converted, through the structure of the balls and ramps, into a torque in the opposite rotational direction, thereby reducing the operator's burden and enhancing stability.

[0004] According to a first aspect of the present disclosure, a joint module for a robotic arm is provided, including: a base having a first ball ramp assembly, the first ball ramp assembly including multiple first ball ramps; a fixing ring having multiple receiving slots, the multiple receiving slots configured to accommodate multiple balls, where the multiple balls are disposed between the base and the fixing ring; a central shaft passing through the base and the fixing ring; and an elastic member disposed on one side of the fixing ring. When the central shaft drives the fixing ring to rotate, the multiple balls slide along the multiple first ball ramps, such that the fixing ring is causedto generate an axial displacement to compress the elastic member.

[0005] In some implementations of the first aspect, a surface of each of the multiple first ball ramps has a groove.

[0006] In some implementations of the first aspect, the fixing ring further has multiple clearance spaces arranged corresponding to the multiple first ball ramps.

[0007] In some implementations of the first aspect, the base further has a second ball ramp assembly, the second ball ramp assembly including multiple second ball ramps, and a first radius of curvature of each of the multiple first ball ramps is greater than a second radius of curvature of each of the multiple second ball ramps.

[0008] In some implementations of the first aspect, the joint module further including: a friction washer fixed to the central shaft; and a friction washer cover, when the central shaft rotates, the friction washer and the friction washer cover form a frictional contact surface.

[0009] In some implementations of the first aspect, one end of each of the multiple first ball ramps is provided with a ball stop structure.

[0010] In some implementations of the first aspect, further including a fixing member, where the central shaft includes a central shaft drive slot, the fixing ring includes a fixing ring drive slot, the central shaft drive slot and the fixing ring drive slot are correspondingly arranged to form an accommodation space, and the fixing member is disposed in the accommodation space.

[0011] In some implementations of the first aspect, each of the multiple first ball ramps includes a forward compensation ramp segment and a reverse compensation ramp segment with different slopes.

[0012] In some implementations of the first aspect, each of the multiple clearance spaces has a chamfered structure at two ends of each of the multiple clearance spaces.

[0013] In some implementations of the first aspect, multiple first starting positions of the multiple first ball ramps are uniformly distributed in a circular arrangement, and multiple second starting positions of the multiple second ball ramps are uniformly distributed in another circular arrangement.

[0014] According to a second aspect of the present disclosure, a robotic arm is provided, including: multiple arm segments; and a joint module configured to connect the multiple arm segments, the joint module including: a base having a first ball ramp assembly, the first ball ramp assembly including multiple first ball ramps; a fixing ring having multiple receiving slots, the multiple receiving slots configured to accommodate a multiple balls, where the multiple balls are disposed between the base and the fixing ring; a central shaft passing through the base and the fixing ring; and an elastic member disposed on one side of the fixing ring. When the central shaft drives thefixing ring to rotate, the multiple balls slide along the multiple first ball ramps, such that the fixing ring is caused to generate an axial displacement to compress the elastic member.

[0015] In some implementations of the second aspect, a surface of each of the multiple first ball ramps has a groove.

[0016] In some implementations of the second aspect, the fixing ring further has multiple clearance spaces arranged corresponding to the multiple first ball ramps.

[0017] In some implementations of the second aspect, the base further has a second ball ramp assembly, the second ball ramp assembly including multiple second ball ramps, and a first radius of curvature of each of the multiple first ball ramps is greater than a second radius of curvature of each of the multiple second ball ramps.

[0018] In some implementations of the second aspect, the robotic arm including: a friction washer fixed to the central shaft; and a friction washer cover, when the central shaft rotates, the friction washer and the friction washer cover form a frictional contact surface.

[0019] In some implementations of the first aspect, one end of each of the multiple first ball ramps is provided with a ball stop structure.

[0020] In some implementations of the second aspect, the joint module further includes a fixing member, the central shaft includes a central shaft drive slot, the fixing ring includes a fixing ring drive slot, the central shaft drive slot and the fixing ring drive slot are correspondingly arranged to form an accommodation space, and the fixing member is disposed in the accommodation space.

[0021] In some implementations of the second aspect, each of the multiple first ball ramps includes a forward compensation ramp segment and a reverse compensation ramp segment with different slopes.

[0022] In some implementations of the second aspect, each of the multiple clearance spaces has a chamfered structure at two ends of each of the multiple clearance spaces.

[0023] In some implementations of the second aspect, multiple first starting positions of the multiple first ball ramps are uniformly distributed in a circular arrangement, and multiple second starting positions of the multiple second ball ramps are uniformly distributed in another circular arrangement.[Brief Description of Drawings]

[0024] Aspects of the present disclosure are best understood from the following detailed disclosure when read with the accompanying drawings. Various features are not drawn to scale. Dimensions of various features may be arbitrarily increased or reduced for clarity of discussion.

[0025] FIG. 1 is an exploded diagram illustrating a joint module, according to an implementation of the present disclosure.

[0026] FIG. 2 is a diagram illustrating a base, according to an implementation of the present disclosure.

[0027] FIG. 3 is a diagram illustrating a fixing ring, according to an implementation of the present disclosure.

[0028] FIG. 4 A is a diagram illustrating portions of a joint module, according to an implementation of the present disclosure.

[0029] FIG. 4B is a side view diagram illustrating portions of a joint module, according to an implementation of the present disclosure.

[0030] FIG. 5 is a diagram illustrating portions of a joint module, according to an implementation of the present disclosure.

[0031] FIG. 6 is a diagram illustrating a base, according to an implementation of the present disclosure.[Description of Embodiments]

[0032] The following contains specific information related to implementations of the present disclosure. The drawings and their accompanying detailed disclosure are merely directed to implementations. However, the present disclosure is not limited to these implementations. Other variations and implementations of the present disclosure will be obvious to those skilled in the art.

[0033] Unless noted otherwise, like or corresponding elements among the drawings may be indicated by like or corresponding reference numerals. Moreover, the drawings and illustrations in the present disclosure are generally not to scale and are not intended to correspond to actual relative dimensions.

[0034] For consistency and ease of understanding, like features may be identified (although, in some examples, not illustrated) by the same numerals in the drawings. However, the features in different implementations may be different in other respects and shall not be narrowly confined to what is illustrated in the drawings.

[0035] References to '‘one implementation,” “an implementation,” “example implementation,” “various implementations,” “some implementations,” “implementations of the present application,” etc., may indicate that the implementation(s) of the present application so described may include a particular feature, structure, or characteristic, but not every possible implementation of the present application necessarily includes the particular feature, structure, or characteristic. Further, repeated use of the phrase “in one implementation,” or “in an example implementation,” “an implementation,” do not necessarily refer to the same implementation, although they may. Moreover, any use of phrases like “implementations” in connection with “the present application” are never meant to characterize that all implementations of the present application must include the particular feature,structure, or characteristic, and should instead be understood to mean “at least some implementations of the present application” includes the stated particular feature, structure, or characteristic.

[0036] The term “coupled” is defined as connected, whether directly or indirectly through intervening components, and is not necessarily limited to physical connections. The term “comprising,” when utilized, means “including, but not necessarily limited to”; it specifically indicates open-ended inclusion or membership in the so-described combination, group, series, and the equivalent.

[0037] The expression “at least one of A, B and C” or “at least one of the follow ing: A, B and C” means “only A, or only B, or only C, or any combination of A, B and C.” The terms “system” and “network” may be used interchangeably. The term “and / or” is only an association relationship for describing associated objects and represents that three relationships may exist such that A and / or B may indicate that A exists alone, A and B exist at the same time, or B exists alone. The character “ / ” generally represents that the associated objects are in an “or” relationship.

[0038] For the purposes of explanation and non-limitation, specific details, such as functional entities, techniques, protocols, and standards, are set forth for providing an understanding of the disclosed technology. In other examples, detailed disclosure of well-known methods, technologies, systems, and architectures are omitted so as not to obscure the present disclosure with unnecessary details.

[0039] FIG. 1 is an exploded diagram illustrating a joint module, according to an implementation of the present disclosure.

[0040] Referring to FIG. 1, the joint module 100 is suitable for a robotic arm 1 and may provide effective weight compensation functionality to an operator. The joint module 100 includes: a housing 10, a base 110, a fixing ring 120, a central shaft 130, an elastic member 140, and multiple balls 150. In some implementations, a robotic arm including the joint module 100 may be used in applications, such as surgical robots, gimbal systems for photographic equipment, adjustable stands for laboratory instruments, and the like. The present disclosure is not limited thereto. A common characteristic of these application scenarios is that these scenarios involve a mechanical structure rotating about a fixed axis, which is subject to the influence of gravity or other external forces during rotation.

[0041] In some implementations, robotic arms often face balance issues caused by gravity during an operation. For example, w hen a user rotates a robotic arm with a heavy load attached to its front end, the operator may need to exert significant force to stabilize the robotic arm and precisely adjust its position. The joint module 100 of the present implementation, through the cooperation of the fixing ring 120, the base 110, and the elastic member 140, operates as follows: when the central shaft 130 drives the fixing ring 120 to rotate in a first direction (e.g., clockwise), the balls 150 slideupward along ramps on the surface of the base 110, causing the fixing ring 120 to generate an axial displacement that compresses the elastic member 140. The force exerted by the compressed elastic member 140 on the fixing ring 120 is converted, through the structure of the balls 150 and the ramps, into a torque in the opposite direction of the first direction (e.g., counterclockwise), preventing the robotic arm from rapidly descending due to gravity and thereby enhancing operational convenience and safety.

[0042] In some implementations, the joint module 100 may reduce the operational burden when an operator adjusts the angle of the equipment. For example, when lifting a sagging robotic arm with a heavy load attached to its front end, moving the robotic arm may require significant effort from the operator. The joint module 100 of the present implementation, through the cooperation of the fixing ring 120, the base 110, and the elastic member 140, operates as follows: when the central shaft 130 dnves the fixing ring 120 to rotate in a second direction (e.g., counterclockwise), the balls 150 slide downward along the ramps on the surface of the base 110. At this time, the force exerted by the still-compressed elastic member 140 on the fixing ring 120 is converted, through the structure of the balls 150 and the ramps, into a torque in the same direction as the second direction (e.g., counterclockwise), reducing the force that the operator needs to apply and making the movement of the arm easier.

[0043] For example, in a medical surgical environment, a surgeon needs to precisely control a robotic arm to perform surgical operations. Without the assistance of the joint module 100, the surgeon must exert additional force to counteract the downward pull of the weight at the front end of the robotic arm, which increases the operational burden and may lead to mechanical structure fatigue or even damage due to excessive weight. Through the j oint module 100, the force required by the surgeon during operation may be reduced.

[0044] Referring back to FIG. 1, the housing 10 serves as an external protective structure for the joint module 100 and may be fixedly installed in a piece of equipment with a rotating shaft to accommodate and protect internal components. The base 110 is located at the bottom position within the housing 10, serving as the primary load-bearing structure.

[0045] FIG. 2 is a diagram illustrating a base, according to an implementation of the present disclosure.

[0046] Referring to FIG. 1 and FIG. 2 together, the base 110 includes a first ball ramp assembly 1100. The first ball ramp assembly 1100 includes multiple first ball ramps, which divide the base 110 circumferentially into multiple equal segments. For example, when the first ball ramp assembly 1100 includes three first ball ramps, each first ball ramp occupies a 120-degree angular range on the base 110. When the first ball ramp assembly 1100 includes four first ball ramps, each first ball rampoccupies a 90-degree angular range on the base 110. This uniform configuration ensures that the load distribution of multiple balls 150 on the base 110 is even, enhancing the operational stability of the j oint module 100.

[0047] The fixing ring 120 is disposed on one side of the base 110 and includes multiple receiving slots 1200 configured to accommodate multiple balls 150. The number of receiving slots 1200 corresponds to the number of first ball ramps in the first ball ramp assembly 1100, ensuring that each first ball ramp is paired with a corresponding ball 150. For example, when the first ball ramp assembly 1100 includes three first ball ramps, the fixing ring 120 correspondingly includes three receiving slots 1200, each receiving slot 1200 accommodating one ball 150. The design of the receiving slots 1200 prevents relative movement between the balls 150 and the fixing ring 120, such that when the fixing ring 120 rotates, the balls 150 rotate together with the fixing ring 120 and simultaneously slide along the corresponding first ball ramps on the base 110.[004S] The central shaft 130 passes through the center of the base 110 and the fixing ring 120, serving as the rotational axis of the joint module 100. The central shaft 130 may transmit external rotational motion to the fixing ring 120, causing the fixing ring 120 to drive the multiple balls 150 to slide along their respective first ball ramps. In some implementations, the central shaft 130 may be fixedly connected to an arm segment of the robotic arm, such that when an operator rotates the robotic arm, the rotational motion of the arm segment is directly transmitted to the central shaft 130. As the central shaft 130 rotates, the central shaft 130 drives the fixing ring 120 to rotate synchronously, thereby activating the compensation mechanism of the joint module 100. This configuration enables the joint module 100 to provide appropriate assistive force, based on the actual motion state of the robotic arm, when needed by the operator.

[0049] The elastic member 140 is disposed on one side of the fixing ring 120. When an operator manipulates the robotic arm to rotate the central shaft 130 in a certain direction, the balls 150 on the fixing ring 120 rotate in the same direction as the fixing ring 120 and slide upward along the first ball ramps, causing the fixing ring 120 to generate an axial displacement that compresses the elastic member 140.

[0050] For example, when the central shaft 130 rotates, causing the balls 150 to slide upward along the first ball ramps, the sliding of the balls 150 pushes the fixing ring 120 to generate an axial displacement and compress the elastic member 140. At this time, the axial restoring force of the elastic member 140 is transmitted back to the balls 150 through the fixing ring 120. Due to the slope of the first ball ramps, the restoring force of the elastic member 140 generates a force on the balls 150 that causes them to slide downward along the ramps. This force, through the balls 150 and the fixing ring 120, produces a torque on the central shaft 130 in the opposite direction to the rotation,thereby stabilizing the operation of the robotic arm.

[0051] Referring to FIG. 2, the base 110 provides the ramp structure required for the sliding of the balls 150. Specifically, the first ball ramp assembly 1100 on the base 110 includes multiple first ball ramps, which divide the base 110 circumferentially into equal angular segments. This uniform configuration ensures that the load distribution of multiple balls 150 on the base 110 is even, enhancing the operational stability of the joint module 100.

[0052] In some implementations, each first ball ramp may include two segments with different slopes: a forward compensation ramp segment 1130 and a reverse compensation ramp segment 1120. The forward compensation ramp segment 1130, for example, has a first slope, while the reverse compensation ramp segment 1120, for example, has a second slope. The first slope may be greater than the second slope.

[0053] In some implementations, with the vertically upward direction of the housing 10 as the reference line, a home position of the j oint module 100 is defined. An operator may rotate the robotic arm clockwise or counterclockwise relative to the reference line to approach or move away from a target object. When the front-end module of the robotic arm moves toward the target object, the center of mass of the front-end module of the robotic arm shifts relative to the joint module 100 to the clockwise or counterclockwise side of the reference line, thereby generating a larger negative gravitational torque (i.e., gravity-biased rotational tendency) in the direction of the offset side. When the operator rotates the robotic arm toward the offset side direction, the balls 150 slide along the forward compensation ramp segment 1130. The forward compensation ramp segment 1130 has a larger slope, which can convert the restoring force of the elastic member 140 into a higher compensation torque, thereby assisting the operator without the need to apply additional lifting force to support the self-w eight of the robotic arm. In contrast, in the non-offset side rotation direction (where the robotic arm moves away from the target object, i.e., the angle range with smaller gravitational torque), when an operator rotates the robotic arm toward the non-offset side direction, the balls 150 slide along the reverse compensation ramp segment 1120. The reverse compensation ramp segment 1120 has a smaller slope, which can avoid instability caused by excessive compensation. This structural design enables the joint module 100 to provide appropriate compensation during both clockwise and counterclockwise rotations of the robotic arm.

[0054] In some implementations, the slope of the forward compensation ramp segment 1130 is designed to be in the range of 25 degrees to 35 degrees, and the slope of the reverse compensation ramp segment 1120 is designed to be in the range of 10 degrees to 15 degrees.

[0055] In some implementations, the surface of the first ball ramp assembly 1100 includes a groove structure, which may guide the balls 150 to slide stably along the track, preventing the balls150 from deviating from the ramp surface during movement and ensuring the operational stability of the joint module 100.

[0056] In some implementations, one end of each first ball ramp includes a ball stop structure 1140. Specifically, the ball stop structure 1140 forms a height difference with the surface of the first ball ramp, preventing the balls 150 from continuing to slide when the balls 150 encounter the ball stop structure 1140. For example, when the first ball ramp assembly 1100 includes two first ball ramps, the highest point of each first ball ramp is provided with a ball stop structure 1140. When a ball 150 slides to the highest point of the first ball ramp, the ball 150 contacts the ball stop structure 1140. Due to the height difference between the ball stop structure 1140 and the first ball ramp, the ball stop structure 1140 prevents the ball 150 from moving further, thereby avoiding excessive compression of the elastic member 140 beyond its design limit. Advantageously, this design ensures that the rotation angle of the joint module 100 remains within a safe operating range, protecting internal components from damage due to extreme positions.

[0057] In some implementations, each first ball ramp includes a ramp starting position 1110, and these ramp starting positions 1110 are uniformly distributed in a circular arrangement on the base 110. Specifically, the positions of the ramp starting positions 1110 are determined through calculations, which consider the motion characteristics and weight compensation requirements of the robotic arm to determine the direction and effect of the weight compensation of the joint module 100.

[0058] In detail, the ramp starting position 1110 corresponds to the position where the compression of the elastic member 140 is minimal, i.e., the state where the joint module 100 requires the least weight compensation effect. In some implementations, when the balls 150 are located at the ramp starting positions 1110, the connected arm segment of the robotic arm is in a vertical state, where the influence of gravity on the joint is minimal. In other words, starting from the ramp starting position 1110, the balls 150 may slide in two directions, toward the forward compensation ramp segment 1130 or the reverse compensation ramp segment 1120. corresponding to the compensation requirements for upward or downward rotation of the robotic arm, respectively. This calculated origin configuration ensures that the joint module 100 may provide appropriate assistive effects during bidirectional rotation of the robotic arm.

[0059] FIG. 3 is a diagram illustrating a fixing ring, according to an implementation of the present disclosure.

[0060] Referring to FIG. 3, the fixing ring 120 in an implementation of the present disclosure includes receiving slots 1200, clearance spaces 1210, and a central shaft aperture 1220. The fixing ring 120 is responsible for accommodating and guiding the movement of the balls 150 within thejoint module 100 while cooperating with the central shaft 130 to achieve rotational functionality.

[0061] Specifically, multiple receiving slots 1200 are distributed around the circumference of the fixing ring 120 to accommodate multiple balls 150, preventing relative movement between the balls 150 and the fixing ring 120. These receiving slots 1200 are uniformly distributed in a circular arrangement on the fixing ring 120, with their number matching the number of first ball ramps, ensuring that each ball 150 is accurately positioned between the fixing ring 120 and the base 110.

[0062] In some implementations, the fixing ring 120 includes multiple clearance spaces 1210, which are arranged corresponding to the first ball ramps. The purpose of the clearance spaces 1210 is to ensure that the fixing ring 120 does not collide or rub against the ramp structure on the base 110 during rotation and axial movements.

[0063] In some implementations, the clearance spaces 1210 may be openwork structures. An openwork structure involves completely removing material from the fixing ring 120 at positions corresponding to the first ball ramps, forming fully penetrating openings. This openwork structure provides maximum clearance, ensuring that the fixing ring 120 does not contact the ramp portions of the base 110. The shape and size of the openwork structure are designed based on the trajectory of the first ball ramps.

[0064] In some implementations, the clearance spaces 1210 may be groove structures. A groove structure involves forming recesses on the surface of the fixing ring 120 w ithout fully penetrating the structure of the fixing ring 120. The groove structure provides necessary clearance while maintaining the overall structural strength of the fixing ring 120. The depth of the grooves is designed based on the maximum height of the first ball ramps, ensuring no contact occurs throughout the entire rotational range of the fixing ring 120. Advantageously, the groove-structured clearance spaces 1210 are suitable for applications requiring higher structural strength.

[0065] For example, when the robotic arm bears a load requiring weight compensation, the rotation of the central shaft 130 drives the fixing ring 120 to rotate, causing the balls 150 in the receiving slots 1200 to move along the first ball ramps and push the fixing ring 120 to compress the elastic member 140. During this process, the clearance spaces 1210 ensure that the structure of the fixing ring 120 does not physically collide or rub against the ramp portions of the base 110, maintaining smooth operation of the mechanism.

[0066] In some implementations, the clearance spaces 1210 may include additional chamfered structures at their edge positions. Specifically, the chamfered structures may be designed as semicircular or beveled shapes, located at two ends of the clearance spaces 1210, i.e., at the starting and ending positions of the clearance spaces 1210. This chamfered design involves additional material removal at the boundaries of the clearance spaces 1210, creating larger clearance areas. Theprimary purpose is to ensure that, when the fixing ring 120 rotates to its maximum angle, such as when the balls 150 slide to the highest point of the first ball ramps, the edge structure of the fixing ring 120 does not contact the ramp portions of the base 110. In some implementations, the depth, width, and chamfer angle of the chamfered structures may be optimized based on the maximum height of the first ball ramp assembly 1100, the shape of the ramps, and the rotational range of the fixing ring 120. The present disclosure is not limited thereto.

[0067] FIG. 4A is a diagram illustrating portions of a joint module, according to an implementation of the present disclosure. FIG. 4B is a side view diagram illustrating portions of a joint module, according to an implementation of the present disclosure.

[0068] Referring to FIG. 4A and FIG. 4B, these figures illustrate the overall structure of the joint module 100 after assembly from different perspectives. FIG. 4A shows the spatial arrangement of main components, such as the base 110, fixing ring 120, central shaft 130, and balls 150, while FIG. 4B illustrates the stacking relationship of the components and the initial state of the elastic member 140 when the elastic member 140 is not compressed. It should be noted that the detailed transmission mechanism between the central shaft 130 and the fixing ring 120, including the penetration details of the central shaft 130 and the specific structure of the fixing member 1310 that prevents relative rotation between the central shaft 130 and the fixing ring 120, will be described in detail with reference to FIG. 5.

[0069] Specifically, in the assembled state, the base 110 is located at the bottom of the joint module 100, with the first ball ramps on the base 110 cooperating with the receiving slots 1200 of the fixing ring 120. Multiple balls 150 are positioned between the base 110 and the fixing ring 120. Each ball 150 is fixed by a receiving slot 1200 to prevent relative movement with the fixing ring 120 and contacts the surface of the corresponding first ball ramp to enable sliding, forming a stable motion transmission mechanism. The central shaft 130 passes through the center of the base 110 and the fixing ring 120, serving as the rotational axis of the entire joint module 100. The elastic member 140 is disposed on one side of the fixing ring 120, providing axial restoring force during the operation of the joint module 100.

[0070] FIG. 4B illustrates the initial state of the joint module 100, where the elastic member 140 maintains its natural length without being compressed, and multiple balls 150 are positioned near the ramp starting positions 1110 of their respective first ball ramps. At this point, the joint module 100 is in a balanced position, providing no additional compensation force. When an operator begins to rotate the robotic arm, the central shaft 130 drives the fixing ring 120 to rotate synchronously, causing the multiple balls 150 to rotate with the fixing ring 120 and simultaneously slide along their respective first ball ramps. Depending on the direction of sliding, the balls 150 move along either theforward compensation ramp segment 1130 or the reverse compensation ramp segment 1120, generating varying degrees of axial displacement and compressing the elastic member 140.

[0071] As shown in FIG. 4A and FIG. 4B, the design of the joint module 100 makes efficient use of spatial arrangement, with the clearance spaces 1210 ensuring that the fixing ring 120 does not contact the ramp structure on the base 110 during rotation and axial movement. This compact design makes the joint module 100 suitable for applications in space-constrained robotic arm joints.

[0072] FIG. 5 is a diagram illustrating portions of a joint module, according to an implementation of the present disclosure

[0073] Referring to FIG. 5, the transmission mechanism between the fixing ring 120 and the central shaft 130 is achieved through the configuration relationship among the fixing ring drive slot 1230 on the fixing ring 120, the central shaft drive slot 1300 on the central shaft 130, and the fixing member 1310. This ensures that the central shaft 130 may effectively drive the fixing ring 120 to rotate, achieving reliable torque transmission while allowing the fixing ring 120 to move axially along the central shaft 130.

[0074] Specifically, the central shaft 130 includes a central shaft drive slot 1300, and the fixing ring 120 includes a fixing ring drive slot 1230, where the central shaft drive slot 1300 and the fixing ring drive slot 1230 are correspondingly arranged to form an accommodation space. The fixing member 1310 is disposed within this accommodation space, preventing relative rotation between the fixing ring 120 and the central shaft 130, ensuring synchronous rotation. When an operator rotates the robotic arm, the central shaft 130 rotates and drives the fixing ring 120 to rotate through the fixing member 1310.

[0075] In some implementations, the fixing member 1310 may be a steel ball, roller, or other suitable transmission element. The present disclosure is not limited thereto. When multiple central shaft drive slots 1300 and fixing ring drive slots 1230 are present, these corresponding accommodation spaces are uniformly distributed in a circular arrangement, ensuring uniform torque transmission, enhancing the operational stability of the joint module 100, and avoiding wear or failure due to excessive stress at a single point.

[0076] In some implementations, the central shaft drive slot 1300 and the fixing ring drive slot 1230 define the range of axial displacement of the fixing ring 120 along the central shaft 130. In some implementations, the overall height of the first ball ramps may be less than or equal to the axial length of the central shaft drive slot 1300 and the fixing ring drive slot 1230, respectively.

[0077] For example, when an operator rotates the robotic arm, the central shaft 130 rotates and drives the fixing ring 120 through the fixing member 1310, causing the fixing ring 120 to simultaneously drive the multiple balls 150 in its receiving slots 1200 to rotate. As a result, the balls150 slide along the corresponding first ball ramps on the base 110, moving upward or downward along the forward compensation ramp segment 1130 or the reverse compensation ramp segment 1120 depending on the rotation direction, causing the fixing ring 120 to generate varying degrees of axial displacement along the central shaft 130 and compress the elastic member 140, thereby producing corresponding compensation forces at the joint.

[0078] Advantageously, this transmission mechanism not only enables the central shaft 130 to effectively drive the fixing ring 120 to rotate but also reduces resistance during the axial movement of the fixing ring 120 along the central shaft 130.

[0079] In some implementations, the central shaft 130 may adopt a hollow structure design to allow the passage of signal lines or hydraulic / pneumatic lines, providing power, control signals, or fluid power to other systems of the robotic arm, achieving a more compact overall design.

[0080] FIG. 6 is a diagram illustrating a base, according to an implementation of the present disclosure.

[0081] Referring to FIG. 6, in some implementations, the base 110 may include a multi-layer ramp design. Specifically, the base 110 includes a first ball ramp assembly 1100 and a second ball ramp assembly 1150 located inside the first ball ramp assembly 1100. The second ball ramp assembly 1150 includes multiple second ball ramps, each second ball ramp having a second radius of curvature smaller than the first radius of curvature of each first ball ramp. This multi-layer ramp structure enhances the load-bearing capacity of the joint module 100, making it suitable for applications requiring the handling of larger loads.

[0082] Specifically, the first ball ramp assembly 1100 and the second ball ramp assembly 1150 are arranged in a concentric configuration, with the second ball ramp assembly 1150 positioned inside the first ball ramp assembly 1100, maintaining an appropriate spacing to accommodate their respective balls 150 while avoiding mutual interference. Each layer of the ramp assembly may have an independent slope design to allow adjustments based on dilferent load requirements.

[0083] In some implementations, the ramp starting positions of the multiple second ball ramps in the second ball ramp assembly 1150 are uniformly distributed in a circular arrangement to balance the force plane of the elastic member 140. This symmetrical configuration ensures that the balls 150 on each layer of ramps evenly distribute the force when compressing the elastic member 140, preventing tilting or misalignment of the elastic member 140 due to uneven force distribution, thereby enhancing the stability and service life of the joint module 100. In some implementations, the multiple ramp starting positions 1110 of the first ball ramps and the multiple ramp starting positions of the second ball ramps may be circumferentially staggered.

[0084] Additionally, the structure of the second ball ramp assembly 1150 may be similar to thatof the first ball ramp assembly 1100, including, for example, a forward compensation ramp segment 1130, a reverse compensation ramp segment 1120, and a ball stop structure 1140. The multi-layer ramp structure provides greater design flexibility, allowing the number, slope, and distribution of ramps in each layer to be adjusted based on specific application requirements to achieve optimal weight compensation effects. Through the configuration of the second ball ramp assembly 1150, more balls 150 may participate in the compensation process. When an operator rotates the robotic arm, the balls 150 in both the inner and outer layers slide along their respective ramps, collectively acting on the elastic member 140 to provide greater compensation force. Meanwhile, the multi-layer ramp design offers finer force adjustment capabilities.

[0085] In some implementations, the reverse compensation ramp segment 1120 also includes a ball stop structure 1140, such that when the balls 150 slide along the reverse compensation ramp segment 1120 from the ramp starting position 1110, the balls 150 are prevented from continuing to slide upon encountering the ball stop structure 1140 of the reverse compensation ramp segment 1120.

[0086] In some implementations, the joint module 100 may include various structural variations and functional enhancements. For example, the elastic member 140 may take different forms, such as a helical compression spring, a disc spring assembly, or a gas-liquid elastic cylinder, to accommodate various application requirements and spatial constraints. The present disclosure is not limited thereto.

[0087] In some implementations, to accommodate different load conditions and compensation requirements, the joint module 100 may further include a preload adjustment mechanism. Specifically, the preload adjustment mechanism may include adjustment elements, such as fine-tuning nuts, screws, wedges on the spring seat, or the fixing ring 120, to modify the initial compression of the elastic member 140, adapting to different preload requirements or providing user-operable compensation force range adjustment. In some implementations, the compression of the elastic member 140 may be automatically adjusted through electric or hydraulic actuators to enhance operational convenience and achieve dynamic compensation control. Advantageously, this automatic adjustment mechanism may adjust the compensation force in real-time based on the actual load conditions of the robotic arm, ensuring optimal weight balance across various operating conditions.

[0088] In some implementations, the joint module 100 may further include a locking device, which may be mounted on the base 110 or the central shaft 130, to fix the fixing ring 120 in place after reaching a target angle. In some implementations, the locking device may take forms, such as an electromagnetic brake or a mechanical latch. The present disclosure is not limited thereto.

[0089] In some implementations, when the locking device employs an electromagnetic brake, it may apply braking force after the robotic arm reaches a predetermined angle. For example, theelectromagnetic brake module, through an electronic control system, enables automatic locking and release. When the robotic arm moves to a preset position or needs to maintain a specific angle, the electromagnetic brake module may be activated to ensure the joint module 100 remains in the desired compensation state. In some implementations, when the locking device employs an electromagnetic brake, related components may be made of non-magnetizable materials, such as 3-series stainless steel, to ensure normal operation of the electromagnetic brake and avoid magnetic interference. Advantageously, the electromagnetic brake offers fast response and precise control, enabling automatic locking and release through the electronic control system, while the mechanical latch provides simplicity and high reliability, suitable for applications requiring manual operation or fail-safe locking.

[0090] In some implementations, the elastic coefficient of the elastic member 140 may be designed by considering multiple factors to achieve optimal weight compensation effects. The design process involves analyzing known parameters, including external weight W. lever arm L, internal mechanism resistance arm I, and spring coefficient KN. For example, the design of the joint module 100 may be optimized based on the overall balance equation:within the joint rotation angle range of m to n degrees, the set of all q> values must satisfy the torque balance or minimum condition. Optimization methods, such as Sequential Quadratic Programming or Interior Point Method, may be used to find the preload force F0 and ramp angle 0 that achieve a local minimum solution for the above equation within the required rotation range of the joint.

[0091] Advantageously, the calculated 0 value may be used to determine the spiral pitch (P) of the ball ramps, using the equation:This spiral pitch determines the axial space requirements of the joint module 100, specifically the height difference of the first ball ramps from the lowest point to the highest point, which in turn determines the maximum effective deformation of the elastic member 140. When the balls 150 slide along the first ball ramps from the starting position to the endpoint, the axial displacement of the fixing ring 120 corresponds to this spiral pitch. Therefore, the design of the spiral pitch must match the operation of the elastic member 140 to ensure that, within the entire compensation angle range, the elastic member 140 provides appropriate elastic force without exceeding its elastic deformation limit.

[0092] In some implementations, the joint module 100 may include an upper cover fixedlyconnected to the fixing ring 120 and having a central shaft aperture for the central shaft 130 to pass through. Specifically, the elastic member 140 may be disposed on one side of the upper cover. When the balls 150 slide along the first ball ramps, they push the fixing ring 120 to move axially, which in turn pushes the upper cover fixedly connected to it, causing the upper cover to compress the elastic member 140. Advantageously, using the upper cover as an intermediate force-transmitting element, provides a stable force transmission path and facilitates the installation and maintenance of the elastic member 140. In some implementations, a thrust bearing or other intermediate element may be disposed between the upper cover and the elastic member 140 to reduce friction and enhance the operational efficiency of the mechanism. The present disclosure is not limited thereto.

[0093] In some implementations, the joint module 100 may include a resistance amplification mechanism to enhance overall performance. Specifically, since robotic arms may have multiple axes and high degrees of freedom, not every axis is suitable for using a ramp-based joint module 100, as the relationship between the rotational motion direction resisting the load and the direction of gravity may cause the weight compensation function to fail. In some implementations, for rotational axes where ramp-based compensation is not applicable, fixed friction may be used to provide load resistance and operational feel.

[0094] For example, the joint module 100 may include a friction washer cover and a friction washer, where the friction washer is fixed to the central shaft 130 and rotates synchronously with it, while the friction washer cover is fixed to the base 110 or other components, remaining stationary. When the central shaft 130 rotates, a frictional contact surface forms between the friction washer and the friction washer cover, providing constant resistance torque that allows the operator to feel appropriate resistance feedback when rotating the equipment. Specifically, the maximum static friction force to be overcome during the rotation of the central shaft 130 may be adjusted by regulating the relative position between the friction washer cover and the base 110 or by adjusting the pressing force between the friction washer and the friction washer cover.

[0095] In some implementations, the friction washer and the central shaft 130 are non-assembling fixed. Specifically, the first side of the friction washer proximate to the friction washer cover has a smaller friction coefficient, while the second side of the friction washer proximate to the central shaft nut has a larger friction coefficient (for example, the friction washer cover and the central shaft nut are made of metal, and the friction washer is made of resin, though the present disclosure is not limited thereto). When the friction washer cover is tightened, the friction w asher cover applies a normal force to the friction washer, creating different maximum static friction torques between the first side and the second side of the friction washer. In other words, when the central shaft 130 rotates, the second side has relatively large friction force, causing the frictionwasher to be driven by the central shaft 130; the first side has relatively small friction force, causing relative rotation between the friction washer and the friction washer cover, further creating a damping feel from the relatively small friction force. In some implementations, a disc spring may be added to the side of the friction washer with the larger friction coefficient (e.g., the second side). When the friction washer cover is tightened, the friction washer cover applies a normal force to the disc spring, making it easier for the operator to discern adjustments in the friction force.

[0096] In some implementations, the friction coefficient or braking force of the resistance mechanism (e.g., friction washer or electromagnetic brake) within the equipment is primarily designed based on the terminal load of the robotic arm. Under maximum torque conditions (e.g., when the robotic arm is extended to its maximum distance and carries the maximum load), the required resistance torque for each joint may be calculated, and the parameters of the friction or braking mechanism are designed to match this torque requirement, ensuring appropriate operational feedback and control stability under various operating conditions.

[0097] Another aspect of the present disclosure includes a robotic arm integrating the aforementioned joint module 100. The robotic arm includes multiple arm segments 1, at least one joint connecting adjacent arm segments 1, and the joint module 100 disposed at the joint.

[0098] Specifically, the arm segments 1 of the robotic arm are the primary structural components, each typically having a specific length and load capacity to support and transmit the motion and force of the robotic arm. Multiple arm segments 1 are connected through the joint module 100, forming a mechanical structure capable of multi-angle rotation. Each arm segment 1 may be designed with different shapes, sizes, and materials based on application requirements. Those skilled in the art should understand that the specific structure and operating principles of the joint module 100, including the ramp design of the base 110, the configuration of the receiving slots 1200 on the fixing ring 120, the motion mechanism of the balls 150, and the compensation function of the elastic member 140, have been described in detail in the preceding paragraphs and will not be repeated here.

[0099] In some implementations, the joint module 100 is disposed at the joint, where the central shaft 130 of the joint module 100 is connected to the arm segments 1. This connection allows the rotational motion of the arm segments 1 to be transmitted to the central shaft 130, initiating subsequent assistive processes. The base 110 of the joint module 100 may be fixed to the joint housing 10 or one of the arm segments 1, ensuring a stable mounting position during the motion of the robotic arm.

[0100] In some implementations, in a multi -joint robotic arm, joints at different positions may selectively incorporate the joint module 100 based on their load characteristics. Typically, joints bearing larger gravitational loads are more suitable for incorporating the joint module 100, while fineoperation joints at the end may use other forms of force control mechanisms. This selective configuration effectively provides weight compensation while avoiding unnecessary mechanical complexity.

[0101] The foregoing has described implementations of the present disclosure with reference to the drawings, but the specific configuration is not limited to these implementations and includes design changes within the scope of the present disclosure. Additionally, various modifications may be made within the scope of the claims, and implementations obtained by appropriately combining technical means disclosed in different implementations are also included in the technical scope of the present disclosure. Furthermore, configurations obtained by interchanging elements described in the above implementations that achieve the same effects are also included.

Claims

AMENDED CLAIMS received by the International Bureau on 06 February 2026 (06.02.2026)

1. A joint module for a robotic arm, the joint module comprising: a base having a first ball ramp assembly, the first ball ramp assembly comprising a plurality of first ball ramps; a fixing ring having a plurality of receiving slots, the plurality of receiving slots configured to accommodate a plurality of balls, wherein the plurality of balls is disposed between the base and the fixing ring; a central shaft passing through the base and the fixing ring; and an elastic member disposed on one side of the fixing ring, wherein, when the central shaft drives the fixing ring to rotate, the plurality of balls slides along the plurality of first ball ramps, such that the fixing ring is caused to generate an axial displacement to compress the elastic member, and wherein one end of each of the plurality of first ball ramps is provided with a ball stop structure.

2. The joint module of claim 1, wherein a surface of each of the plurality of first ball ramps has a groove.

3. The j oint module of claim 1 , wherein the fixing ring further has a plurality of clearance spaces arranged corresponding to the plurality of first ball ramps.

4. The j oint module of claim 1 , wherein the base further has a second ball ramp assembly, the second ball ramp assembly comprising a plurality of second ball ramps, and a first radius of curvature of each of the plurality of first ball ramps is greater than a second radius of curvature of each of the plurality of second ball ramps.

5. The joint module of claim 1, further comprising: a friction washer fixed to the central shaft; and a friction washer cover, wherein, when the central shaft rotates, the friction washer and the friction washer cover form a frictional contact surface.

6. The joint module of claim 1, wherein one end of each of the plurality of first ball ramps is provided with a ball stop structure.

7.

6. The joint module of claim 1, further comprising: a fixing member, wherein: the central shaft comprises a central shaft drive slot, the fixing ring comprises a fixing ring drive slot, the central shaft drive slot and the fixing ring drive slot are correspondingly arranged to form an accommodation space, and the fixing member is disposed in the accommodation space.

8. [Claim 71The joint module of claim 1, wherein each of the plurality of first ball ramps comprises a forward compensation ramp segment and a reverse compensation ramp segment with different slopes.

8. The joint module of claim 7, wherein each of the plurality of first ball ramps further comprises: a ramp start position, wherein: the forward compensation ramp segment extends circumferentially from the ramp start position in a first circumferential direction, and the reverse compensation ramp segment extends circumferentially from the ramp start position in a second circumferential direction opposite the first circumferential direction.

9. The joint module of claim 3, wherein each ofthe plurality of clearance spaces has a chamfered structure at two ends of each of the plurality of clearance spaces.

10. The joint module of claim 4, wherein a plurality of first starting positions of the plurality of first ball ramps is uniformly distributed in a circular arrangement, and a plurality of second starting positions of the plurality of second ball ramps is uniformly distributed in another circular arrangement.

11. A robotic arm, comprising: a plurality of arm segments; and a joint module configured to connect the plurality of arm segments, the joint module comprising: a base having a first ball ramp assembly, the first ball ramp assembly comprising a plurality of first ball ramps; a fixing ring having a plurality of receiving slots, the plurality of receiving slots configured to accommodate a plurality of balls, wherein the plurality of balls is disposed between the base and the fixing ring; a central shaft passing through the base and the fixing ring; and an elastic member disposed on one side of the fixing ring, wherein, when the central shaft drives the fixing ring to rotate, the plurality of balls slides along the plurality of first ball ramps, such that the fixing ring is caused to generate an axial displacement to compress the elastic member, and wherein one end of each of the plurality of first ball ramps is provided with a ball stop structure.

12. The robotic arm of claim 11, wherein a surface of each of the plurality of first ball ramps has a groove.

13. The robotic arm of claim 11 , wherein the fixing ring further has a plurality of clearance spaces arranged corresponding to the plurality of first ball ramps.

14. The robotic arm of claim 11, wherein the base further has a second ball ramp assembly, the second ball ramp assembly comprising a plurality of second ball ramps, and a first radius of curvature of each of the plurality of first ball ramps is greater than a second radius of curvature of each of the plurality of second ball ramps.

15. The robotic arm of claim 11, comprising: a friction washer fixed to the central shaft; and a friction washer cover, wherein, when the central shaft rotates, the friction washer and the frictionwasher cover form a frictional contact surface.

16. The robotic arm of claim 11, wherein one end of each of the plurality of first ball ramps is provided with a ball stop structure.

17.

16. The robotic arm of claim 11, wherein: the joint module further comprises a fixing member, the central shaft comprises a central shaft drive slot, the fixing ring comprises a fixing ring drive slot, the central shaft drive slot and the fixing ring drive slot are correspondingly arranged to form an accommodation space, and the fixing member is disposed in the accommodation space.

18.

17. The robotic arm of claim 11, wherein each of the plurality of first ball ramps comprises a forward compensation ramp segment and a reverse compensation ramp segment with different slopes.

18. The robotic arm of claim 17, wherein each of the plurality of first ball ramps further comprises: a ramp start position, wherein: the forward compensation ramp segment extends circumferentially from the ramp start position in a first circumferential direction, and the reverse compensation ramp segment extends circumferentially from the ramp start position in a second circumferential direction opposite the first circumferential direction.

19. The robotic arm of claim 13, wherein each of the plurality of clearance spaces has a chamfered structure at two ends of each of the plurality of clearance spaces.

20. The robotic arm of claim 14, wherein a plurality of first starting positions of the plurality of first ball ramps is uniformly distributed in a circular arrangement, and a plurality of second starting positionsof the plurality of second ball ramps is uniformly distributed in another circular arrangement.International Application No. PCT / US2025 / 047867International Filing Date September 25, 2025Applicant(s) SAVFE TECH LLCInventor(s) HAO-KAI CHOUAttorney Docket No. WO44712STATEMENTClaims of the international application No. PCT / US2025 / 047867, filed onSeptember 25, 2025, are preliminarily amended in compliance with Article 19 PCT.Attached herein are a marked-up version and a clean version of the amended claims. In addition, a transmittal letter specifying the amendments to the claims and the supporting passages in the specification is also attached. The claim amendments are made to more clearly reflect the present invention. No new matter is introduced.Respectfully,Kelvin LiuSCIENBIZIP, P C.550 SOUTH HOPE STREET, SUITE 2825, LOS ANGELES, CA 90071UNITED STATES OF AMERICA

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