Robot driving apparatus including twisted string actuator, variable stiffness structure, and fluid core

Abstract

According to one embodiment of the present disclosure, a robot drive device is disclosed. The robot drive device may include: a string actuator module in which a twisting string is twisted to generate a contracting force according to the rotation of a driving source; a variable stiffness structure driven by the contracting force of the string actuator module; and a fluid core comprising a housing that accommodates at least a portion of the twisting string and a fluid accommodated in the housing.

Description

Technology Field

[0001] The present invention relates to robot driving technology, and more specifically, to a robot driving device comprising a string actuator module that generates a contracting force by twisting a twist string according to the rotation of a driving source, a variable stiffness structure driven by the contracting force of the string actuator module, a housing that accommodates at least a portion of the twist string, and a fluid core including a fluid inside the housing. Background Technology

[0003] Resolving the trade-off between rigidity and compliance has long been a critical challenge for robotic actuation systems. While traditional methods utilizing electromagnetic motors and reduction gears can provide high precision and torque, they have limitations such as increased weight, high inertia, vulnerability to external shocks, and low backdriveability. Conversely, soft actuators, such as pneumatic artificial muscles or shape-memory alloys, offer advantages in terms of flexibility and compliance, but face constraints regarding response speed, energy efficiency, and precise control. Consequently, there is a growing demand for new forms of robotic actuation technology capable of simultaneously achieving mechanical precision and biological flexibility.

[0004] In addition, the Twisted String Actuator (TSA) converts the rotational motion of a motor into linear contraction caused by the twisting of a wire, offering the advantage of achieving a high power-to-weight ratio without the need for a separate heavy gearbox. However, existing TSA-based drive systems have problems such as frictional heat between wires generated during high-speed rotation, wear, control instability during braking, and difficulty in securing structural rigidity when driven independently. Meanwhile, a layered jamming structure that controls relative slip between laminated plates enables variable rigidity, but there are limitations in implementing an integrated drive structure, such as a robot muscle, if it is not organically integrated with the drive system.

[0005] Furthermore, while lubrication, cooling, and damping technologies using magnetic fluids have been proposed individually, there is a need for a technology that links driving force generation, stiffness control, and fluid control by integrating the fluid environment inside the housing where the twist string is placed, the variable stiffness structure, and the control structure of multiple actuators into a single robot drive unit. In particular, in robot applications that require interaction with irregular environments, human collaboration, response to external collisions, heavy weight support, and precision work, there is a need for a new robot drive unit that integrates a retractable drive unit, a variable stiffness structure, and a fluid core.

[0006] Korean registered patent No. 2079376 (February 13, 2020) discloses a graphene / carbon nanotube composite fiber, a method for manufacturing same, and an electrochemical artificial muscle using same. The problem to be solved

[0008] The present disclosure aims to provide a robot drive device that organically combines a string actuator module, which generates a contraction force by twisting a twist string according to the rotation of a driving source; a variable stiffness structure driven by the contraction force of the string actuator module; and a fluid core comprising a housing that accommodates at least a portion of the twist string and a fluid inside the housing. Accordingly, the aim is to realize an integrated robot drive structure that combines contraction drive and structural stiffness control without relying excessively on a separate high-ratio reduction gear.

[0009] As an additional example, the present disclosure aims to provide a robot driving device capable of controlling the fluid distribution, viscous state, and heat transfer path around the twist string by placing the twist section of the twist string inside a housing containing a fluid, and in one embodiment, implementing the fluid as a magnetic fluid and providing a magnetic field generating unit.

[0010] In addition, the present disclosure aims to provide a robot drive device capable of selectively changing the stiffness state of a structure through a variable stiffness structure comprising a stacked plate-type member or sheet-type member and a restraining member that changes the relative movement state between said members based on pressure reduction, electrostatic force, or tension transmission.

[0011] Furthermore, the present disclosure aims to provide a robot drive device in which, when a plurality of string actuator modules are coupled to a single variable stiffness structure, a control unit selects the number of modules to be driven, performs control of the sum based on position, speed, current, or tension, reflects an effective radius model that changes according to the twisting state, and controls the driving conditions of a magnetic field generator corresponding to a fluid core in conjunction with the constraint state of the variable stiffness structure.

[0012] Meanwhile, the technical problem that the present disclosure aims to solve is not limited to the technical problem mentioned above, and various technical problems may be included within the scope obvious to a person skilled in the art from the contents described below. means of solving the problem

[0014] A robot drive device is disclosed according to one embodiment of the present disclosure for realizing the aforementioned problem. The robot drive device may include: a string actuator module in which a twisting string is twisted to generate a contracting force according to the rotation of a driving source; a variable stiffness structure driven by the contracting force of the string actuator module; and a fluid core comprising a housing that accommodates at least a portion of the twisting string and a fluid accommodated in the housing.

[0015] In one embodiment, the driving source includes a motor, and the rotation axis of the motor may be directly coupled to a rotating member that twists the twist string.

[0016] In one embodiment, the twist string may include at least one of a wire, fiber, or filament in which a plurality of strands are arranged in parallel and formed integrally.

[0017] In one embodiment, the twist section of the twist string is disposed inside the housing, and the end of the twist string can be coupled to the variable stiffness structure outside the housing.

[0018] In one embodiment, the fluid includes a magnetic fluid, and the robot driving device may further include a magnetic field generating unit that applies a magnetic field to the magnetic fluid inside the housing.

[0019] In one embodiment, the magnetic field generating unit may include a coil disposed on the inner or outer side of the housing.

[0020] In one embodiment, the twisted string is formed of a conductive material or includes a conductive coating layer, and the magnetic field generating unit may include a power supply unit that applies current to the twisted string.

[0021] In one embodiment, the housing may include a first flow space surrounding the twisted section; a storage space for receiving the fluid; and a first flow path connecting the storage space and the first flow space.

[0022] In one embodiment, the housing may further include a second flow space formed on the housing wall side, spaced apart from the first flow space; and a second flow path connecting the first flow space and the second flow space.

[0023] In one embodiment, a heat exchange jacket may be coupled to the outer side of the housing so as to be in thermal contact with the second flow space.

[0024] In one embodiment, the variable stiffness structure may include a plurality of plate-shaped members or sheet-shaped members that are stacked to extend along the contraction direction of the twist string.

[0025] In one embodiment, the variable stiffness structure may further include a restraining member that changes the relative movement state between adjacent plate-type members or sheet-type members.

[0026] In one embodiment, the restraining member may include a hermetic outer shell surrounding the plurality of plate-shaped members or sheet-shaped members; and a pressure reducing source for reducing pressure inside the hermetic outer shell.

[0027] In one embodiment, the restraining member may include an electrode layer disposed between the adjacent plate-shaped members or sheet-shaped members; and a power supply member that applies voltage to the electrode layer.

[0028] In one embodiment, the restraining member may include a tension transfer member that compresses the plurality of plate-shaped members or sheet-shaped members in a stacking direction according to the contraction force of the string actuator module.

[0029] In one embodiment, the variable stiffness structure may be configured to switch between a first state in which relative sliding between adjacent plate-shaped members or sheet-shaped members is allowed, and a second state in which relative sliding between adjacent plate-shaped members or sheet-shaped members is restricted.

[0030] In one embodiment, the variable stiffness structure may further have an intermediate constraint state between the first state and the second state.

[0031] In one embodiment, a plurality of string actuator modules may be coupled to a single variable stiffness structure.

[0032] In one embodiment, the robot driving device further includes a control unit, and the control unit may be configured to drive the plurality of string actuator modules individually and to select the number of string actuator modules to be driven among the plurality of string actuator modules.

[0033] In one embodiment, the control unit may be configured to control the operation of the plurality of string actuator modules by agreement using at least one of the position, velocity, current, or tension of the plurality of string actuator modules.

[0034] In one embodiment, the control unit may be configured to calculate the contraction amount or output force of the string actuator module using a model that includes an effective radius that changes according to the twist state of the twist string.

[0035] In one embodiment, the robot driving device further includes at least one of a tension sensor, a current sensor, a voltage sensor, a back EMF sensor, a temperature sensor, a structural deformation sensor, or an external force sensor, and the control unit may be configured to control the plurality of string actuator modules based on the detection value of the at least one sensor.

[0036] In one embodiment, the robot driving device further includes a restraining member provided in the variable stiffness structure and a magnetic field generating member corresponding to the fluid core, and the control unit may be configured to change the driving conditions of the magnetic field generating member in conjunction with the driving state of the restraining member.

[0037] According to one embodiment of the present disclosure for realizing the aforementioned objectives, a robot is disclosed. The robot comprises: a driving target part that forms the skeleton or outer shape of the robot and performs a specific operation; and a robot driving device that provides a driving force or a supporting force to the driving target part. The robot driving device may include: a string actuator module that generates a contracting force by twisting a twist string according to the rotation of a driving source; and a fluid core that accommodates at least a portion of the twist string in a fluid. Effects of the invention

[0039] According to the present disclosure, a string actuator module utilizing the contraction drive of a twisted string, a variable stiffness structure changing the relative movement state of a stacked structure, and a fluid core accommodating at least a portion of the string are combined into a single robot drive unit, thereby providing an integrated robot drive configuration in which the driving force generating structure and the structural stiffness control structure are not separated.

[0040] Furthermore, according to an embodiment in which the fluid core includes a magnetic fluid and a magnetic field generating unit, the fluid distribution and viscous state around the twist string can be magnetically controlled, and through a housing structure including a storage space, a first flow space, a first flow space, a second flow space, and a second flow space, and a heat exchange jacket, lubrication, damping, and heat transfer around the string can be integrally implemented in a single core structure.

[0041] Alternatively, according to an embodiment comprising a plate-type member or sheet-type member having a stacked variable stiffness structure, and a restraining member including an airtight outer shell and a pressure reducing source, an electrode layer and a power supply, or a tension transmission member, the structure can selectively form a flexible state, a restricted state, and an intermediate restraint state, so that the same driving device can respond to working environments requiring different stiffness conditions.

[0042] In addition, according to an embodiment in which a plurality of string actuator modules are combined into a single variable stiffness structure, a control unit selects the number of modules to be driven, performs consensus control and calculation based on an effective radius model, and further controls the constraint state of the structure and the driving conditions of the magnetic field generator in conjunction, cooperative driving of a plurality of driving modules, maintenance of tension balance, and state linkage control are possible, thereby improving the operational stability and scalability of the robot driving device.

[0043] Furthermore, the present invention has scalability for application in various robotic fields that simultaneously require retractable actuation, variable stiffness, and fluid-based assistance functions, such as collaborative robots, walking robots, exoskeleton devices, rehabilitation aids, medical robots, space robots, and micro-robots.

[0044] Meanwhile, the effects of the present disclosure are not limited to those mentioned above, and various effects may be included within the scope obvious to a person skilled in the art from the contents described below. Brief explanation of the drawing

[0046] FIG. 1 is a block diagram of a computing device for controlling a robot driving device according to one embodiment of the present disclosure. FIG. 2 is a schematic diagram showing the schematic form of a robot to which a robot driving device according to one embodiment of the present disclosure is applied. FIG. 3 is a cross-sectional view showing the combination of a string actuator module and a fluid core according to one embodiment of the present disclosure. FIG. 4 is another cross-sectional view showing a fluid core according to one embodiment of the present disclosure in more detail. FIG. 5 is a schematic diagram showing a laminated structure of a variable stiffness structure according to one embodiment of the present disclosure. FIG. 6 is a schematic diagram showing a restraining part according to one embodiment of the present disclosure. FIG. 7 is a brief and general schematic diagram of an exemplary computing environment in which embodiments of the present disclosure may be implemented. Specific details for implementing the invention

[0047] Various embodiments are now described with reference to the drawings. In this specification, various descriptions are provided to provide an understanding of the present disclosure. However, it is evident that these embodiments can be practiced without such specific descriptions.

[0048] Furthermore, the term "or" is intended to mean an implicit "or" rather than an exclusive "or." That is, unless otherwise specified or evident from the context, "X uses A or B" is intended to mean one of the natural implicit substitutions. In other words, if X uses A; if X uses B; or if X uses both A and B, "X uses A or B" may apply to any of these cases. Additionally, the term "and / or" as used herein should be understood to refer to and include all possible combinations of one or more of the enumerated related items.

[0049] Additionally, the terms “comprising” and / or “comprising” should be understood to mean that such features and / or components are present. However, the terms “comprising” and / or “comprising” should be understood not to exclude the presence or addition of one or more other features, components and / or groups thereof. Furthermore, unless otherwise specified or clearly evident from the context to indicate a singular form, the singular in this specification and claims should generally be interpreted to mean “one or more.”

[0050] And, the term "at least one of A or B" should be interpreted to mean "a case including only A," "a case including only B," or "a combination of A and B."

[0051] Those skilled in the art should recognize that the various exemplary logical blocks, configurations, modules, circuits, means, logics, and algorithmic steps described in connection with the embodiments disclosed herein may be implemented in electronic hardware, computer software, or a combination of both. To clearly exemplify the interchangeability of hardware and software, various exemplary components, blocks, configurations, means, logics, modules, circuits, and steps have been generally described above in terms of their functionality. Whether such functionality is implemented in hardware or software depends on the specific application and design constraints imposed on the overall system. Skilled technicians may implement the described functionality in various ways for each specific application. However, such decisions regarding implementation should not be construed as going beyond the scope of this disclosure.

[0052] The description of the presented embodiments is provided to enable those skilled in the art to use or practice the present invention. Various modifications to these embodiments will be apparent to those skilled in the art. The general principles defined herein may be applied to other embodiments without departing from the scope of the present disclosure. Thus, the present invention is not limited to the embodiments presented herein. The present invention should be interpreted in the broadest possible scope consistent with the principles and novel features presented herein.

[0054] FIG. 1 is a block diagram of a computing device for controlling a robot driving device according to one embodiment of the present disclosure.

[0055] The configuration of the computing device (100) illustrated in FIG. 1 is merely a simplified example. In one embodiment of the present disclosure, the computing device (100) may include other configurations for performing the computing environment of the computing device (100), and only some of the disclosed configurations may constitute the computing device (100). In one embodiment, the control unit of the robot driving device may be configured to include at least one processor.

[0056] The computing device (100) may include a processor (110), memory (130), and a network unit (150).

[0057] The processor (110) may be composed of one or more cores and may include processors for data analysis and deep learning, such as a central processing unit (CPU), a general purpose graphics processing unit (GPGPU), and a tensor processing unit (TPU) of a computing device. The processor (110) may read a computer program stored in memory (130) and perform data processing for machine learning according to one embodiment of the present disclosure. According to one embodiment of the present disclosure, the processor (110) may perform operations for learning a neural network. The processor (110) may perform calculations for learning a neural network, such as processing input data for learning in deep learning (DL), extracting features from input data, calculating errors, and updating the weights of the neural network using backpropagation. At least one of the CPU, GPGPU, and TPU of the processor (110) may process the learning of a network function. For example, a CPU and a GPGPU can work together to process the learning of a network function and data classification using the network function. Additionally, in one embodiment of the present disclosure, processors of a plurality of computing devices can be used together to process the learning of a network function and data classification using the network function. Furthermore, a computer program executed on a computing device according to one embodiment of the present disclosure may be a CPU, GPGPU, or TPU executable program.

[0058] According to one embodiment of the present disclosure, the memory (130) can store any form of information generated or determined by the processor (110) and any form of information received by the network unit (150).

[0059] According to one embodiment of the present disclosure, the memory (130) may include at least one type of storage medium among a flash memory type, a hard disk type, a multimedia card micro type, a card type memory (e.g., SD or XD memory), RAM (Random Access Memory), SRAM (Static Random Access Memory), ROM (Read-Only Memory), EEPROM (Electrically Erasable Programmable Read-Only Memory), PROM (Programmable Read-Only Memory), magnetic memory, a magnetic disk, and an optical disk. The computing device (100) may operate in conjunction with web storage that performs the storage function of the memory (130) on the internet. The description of the memory described above is merely an example and the present disclosure is not limited thereto.

[0060] A network unit (150) according to one embodiment of the present disclosure can use various wired communication systems such as a public switched telephone network (PSTN), xDSL (x Digital Subscriber Line), RADSL (Rate Adaptive DSL), MDSL (Multi Rate DSL), VDSL (Very High Speed ​​DSL), UADSL (Universal Asymmetric DSL), HDSL (High Bit Rate DSL), and a local area network (LAN).

[0061] In addition, the network unit (150) presented in this specification may use various wireless communication systems such as CDMA (Code Division Multi Access), TDMA (Time Division Multi Access), FDMA (Frequency Division Multi Access), OFDMA (Orthogonal Frequency Division Multi Access), SC-FDMA (Single Carrier-FDMA), and other systems.

[0062] In the present disclosure, the network unit (150) can be configured regardless of the communication mode, such as wired and wireless, and can be configured as various communication networks such as a Local Area Network (LAN), a Personal Area Network (PAN), and a Wide Area Network (WAN). In addition, the network may be a known World Wide Web (WWW) and may utilize wireless transmission technology used for short-range communication, such as Infrared Data Association (IrDA) or Bluetooth.

[0063] The technologies described in this specification can be used not only in the networks mentioned above but also in other networks.

[0065] Hereinafter, various embodiments of the present invention will be described in detail with reference to the drawings.

[0066] FIG. 2 is a schematic diagram showing the schematic form of a robot to which a robot driving device according to one embodiment of the present disclosure is applied.

[0067] Referring to FIG. 2, a schematic form of an exemplary robot including a robot drive device according to one embodiment of the present disclosure is illustrated. According to one embodiment of the present disclosure, the robot drive device (600) may include a string actuator module (200), a variable stiffness structure (300), and a fluid core (400). The string actuator module (200) may function as a drive unit that converts rotational motion generated from a rotary drive source into twisting motion of a linear tension member to generate a longitudinal contraction force, the variable stiffness structure (300) may function as a structural unit that receives the contraction force and is displaced or maintains an attitude, and the fluid core (400) may be understood as a functional unit that forms a fluid environment in which at least a portion of the linear tension member is placed. In this case, the term "robot drive unit" may be used to encompass devices that are positioned in specific parts of a robot to provide driving force or support force, such as single joint drive units, link drive units, robot finger drive units, and drive units for exoskeletons.

[0068] In the present disclosure, "string actuator module" may refer to a module that generates a contraction force by utilizing the reduction in effective length due to the twisting of a twist string (220). Here, "twist string" broadly refers to a linear tension member capable of receiving a torsional load and is not limited to a single wire, but may include multiple strands of wire, fiber, filament, fiber bundle, or a wire with a core-sheath structure. Additionally, "contraction force" may refer to a tensile force or driving force generated in the longitudinal direction of the string due to the reduction in the effective length of the twist string. Meanwhile, "variable stiffness structure" may refer to a structure in which effective stiffness, bending resistance, or deformation resistance can be changed depending on the relative arrangement or constraint state of multiple members constituting the structure, and "fluid core" may refer to a functional unit that provides a fluid environment around the twist string by accommodating fluid inside a housing. The above fluid may comprise a liquid or semi-fluid medium that can be used for at least one of lubrication, cooling, damping, load transfer, or friction reduction, and in one embodiment, may be a magnetic fluid in which magnetic particles are dispersed.

[0069] According to one embodiment of the present disclosure, the string actuator module (200), the variable stiffness structure (300), and the fluid core (400) are not arranged independently in parallel with each other, but can be coupled together such that the contraction force of the string actuator module (200) is transmitted to the variable stiffness structure (300), and at least a portion of the twisted string (220) constituting the string actuator module (200) is disposed inside the fluid core (400). More specifically, the twisted section (240) of the string actuator module (200) can be disposed inside the housing (410) of the fluid core (400), and the end of the twisted string (220) or the section extending outside the housing can be coupled to the variable stiffness structure (300). Accordingly, a structure can be formed in which the core section where twisting and contraction of the twist string (220) occur and the section where the contraction force is transmitted to the structure are functionally separated yet mechanically continuous.

[0070] In this disclosure, the terms “arrangement” or “combination” do not necessarily mean only integral molding or fixed combination, but may include rotatable combination, sliding combination, hinge combination, clamp combination, insertion combination, cable combination, or states functionally linked by tension transmission. For example, the end of the twist string (220) may be connected to the end, middle, or tension transmission portion of the variable stiffness structure (300), and the variable stiffness structure (300) may be arranged in a direction substantially parallel to the contraction direction of the string or at a certain angle. Additionally, the fluid core (400) may be formed along the entire length of the string actuator module (200), but may also be formed to selectively surround only the section where the twist is concentrated. Thus, this disclosure may provide an integrated robot drive structure in which the combined action of rotation-twist-contraction-structural deformation takes place within a fluid environment.

[0071] According to one embodiment of the present disclosure, the twist string (220) may include an input section that is rotated by a rotating member (230), a twist section (240) where actual twisting is concentrated to form a twist, and an output section that extends from the twist section (240) and is coupled to a variable stiffness structure (300). At this time, the twist section (240) may be located inside the housing (410), and the output section may be drawn out to the outside by penetrating the housing (410). The penetration portion of the housing (410) may further be provided with a seal member, a guide member, or a friction-reducing guide that allows relative movement of the twist string (220) while suppressing external leakage of fluid. Accordingly, a separable structure may be implemented in which the interaction between the fluid and the string is maintained inside the housing (410), and tension transmission for driving the structure is performed outside the housing (410).

[0072] Additionally, the fact that the end of the twist string (220) is coupled to the variable stiffness structure (300) may mean that the end may be directly or indirectly connected to the outer shell, end frame, compression plate, link portion, tension band, tension transmission portion, or a separate fastening portion of the structure. Accordingly, the end is not limited to being fixed at a single point of the structure, but may be connected to transmit tension in a direction that compresses the laminated structure, induce a deformation of the structure's orientation, or support a specific part of the structure. The present disclosure may have structural integrity in that the path of the twist string continuously connects the inside of the fluid core and the outside of the structure, allowing a single linear tension member to simultaneously perform both functions of fluid control and structure driving.

[0073] According to one embodiment of the present disclosure, the string actuator module (200) may have a non-linear correspondence between the amount of rotation of the driving source (210) and the amount of contraction of the twist string (220). More specifically, the effective contraction length of the twist string (220) may be determined by a geometric relationship between the initial wire length, the radius of the wire bundle, and the rotation angle applied by the driving source (210). According to the geometric relationship, in the initial twisting section, the amount of contraction per unit increase in the rotation angle is relatively large, and as twisting progresses, the amount of contraction per the same unit rotation may gradually decrease. On the other hand, the ratio of the output tensile force of the twist string (220) to the torque of the driving source (210), i.e., the mechanical gain, may increase as twisting progresses.

[0074] These characteristics are inherent in the geometric structure of the twist string (220) itself, so that high speed and low torque characteristics can be exhibited in the early stages of driving and low speed and high torque characteristics in the later stages of driving without a separate transmission mechanism. For example, in sections where the robot drive unit (600) must approach a target position quickly, a large contraction speed in the early stages of twisting can be utilized, and in sections where an external object must be grasped or a heavy load must be supported, a high mechanical gain in the later stages of twisting can be utilized. Such non-linear transmission characteristics can provide a structural basis that enables the string actuator module (200) to respond flexibly to the output range without relying excessively on the reduction gear.

[0075] Additionally, the above non-linear transmission characteristics may be taken into account by the control algorithm of the control unit (500). For example, the control unit (500) may correct the speed command or current command for the driving source (210) by reflecting changes in mechanical gain and contraction speed corresponding to the current twisting state. In this case, the correction may be performed in the direction of setting the rotational speed of the driving source (210) low to suppress excessive contraction speed in the initial twisting section, or increasing the torque of the driving source (210) to secure sufficient output tensile force in the later twisting section. Accordingly, by combining the non-linear transmission characteristics of the string actuator module (200) and the correction control of the control unit (500), precise control over a wide output range can be achieved even in a direct drive structure that does not rely on a high-ratio reduction gear.

[0076] In the present disclosure, the term "power supply unit" may be used as a higher-level concept encompassing a first power supply unit that applies current to a conductive twisted string and a second power supply unit that applies voltage to an electrode layer. The first power supply unit and the second power supply unit may share the same power system or may be implemented as independent power systems.

[0077] According to one embodiment of the present disclosure, the robot drive unit (600) may be implemented as a single modular type comprising only one string actuator module (200). In this case, a single twisted string (220) or a plurality of linear tension members within a single module may be configured to drive a single variable stiffness structure (300). Such a single modular structure may be suitable for a relatively simple bending drive, a single degree of freedom drive, a linear contraction drive, or a small robot drive unit. Meanwhile, according to another embodiment, the robot drive unit (600) may be implemented to include a plurality of string actuator modules (200), and said plurality of string actuator modules (200) may be coupled to a single variable stiffness structure (300). In this case, each module may apply tension to the variable stiffness structure (300) at different locations, share contraction forces in the same direction, or be selectively driven at different times.

[0078] In a multiple modular embodiment, each string actuator module (200) may be a module of the same shape, or a heterogeneous module having different string lengths, different output ranges, different fluid core sizes, or different placement angles. Additionally, the multiple modules may be spaced apart along the longitudinal direction of the variable stiffness structure (300), dispersed along the periphery direction of the structure, or symmetrically arranged on both sides of the structure. Such a multiple modular configuration can be combined with a control structure described later to expand to selective driving based on the required load, synchronous driving between multiple modules, or a stepwise driving method linked to the stiffness state of the structure. Accordingly, the entire structure of the present disclosure can encompass from a basic embodiment based on a single driving module to a cooperative driving embodiment of multiple modules.

[0080] FIG. 3 is a cross-sectional view showing the combination of a string actuator module and a fluid core according to one embodiment of the present disclosure.

[0081] According to one embodiment of the present disclosure, a string actuator module (200) may include a driving source (210), a rotating member (230), and a twisted string (220). The driving source (210) is a component that generates rotational power and may include a motor, a servo motor, a stepper motor, a brushless motor, or other rotary actuator. The rotating member (230) is a component that transmits the rotational force of the driving source (210) to the twisted string (220) to cause the twisted string (220) to undergo torsional deformation, and may be implemented in the form of a shaft, a chuck, a drum, a torsional capstan, a slotted rotor, or a rotating hub for string binding. The twisted string (220) may be a linear tension member coupled to the rotating member (230) such that torsion accumulates in the twisted section (240) as it rotates, and consequently, longitudinal contraction occurs.

[0082] In the present disclosure, "directly coupled to a rotating member" may mean a configuration in which the rotational force of the driving source (210) is not transmitted after being converted into torque by a reduction gear, but rather the rotation axis of the driving source (210) or a transmission axis rotating integrally with it is directly connected to a rotating member (230) that twists the twist string (220). However, "direct coupling" here does not mean only integral molding in terms of the coupling format, but may encompass non-reduction type torque transmission relationships including couplers, chucks, clamps, fastening sleeves, bonding, or press fitting. Accordingly, the present disclosure may include a string-based driving structure that directly transmits rotational motion into twisting motion without presupposing a high-ratio reduction gear.

[0083] According to one embodiment of the present disclosure, the driving source (210) may include a motor, and the rotation axis of the motor may be directly coupled to a rotating member (230). For example, the rotating member (230) may be integrally formed at the end of the output shaft of the motor, or may be coupled through a separate fastening hole and a fixing member. As another example, the rotating member (230) may have a hollow structure, and one end or a plurality of strands of linear tension members of a twisted string (220) may be attached to the inside or outer surface of the hollow structure. In this case, as the motor rotates, the rotating member (230) rotates, and the linear tension members attached to the rotating member (230) may twist together to form a twisted section (240).

[0084] Additionally, the rotating member (230) may include a guide groove, an insertion groove, a clamp slot, or a radial fastening portion to maintain the initial alignment state of the twisted string (220). The shape of the rotating member (230) may be a single slot type structure that twists a single string bundle, or a porous or multi-channel type structure that maintains multiple strands at regular intervals. Accordingly, the combined structure of the driving source and the rotating member of the present disclosure is not limited to a single form, and various variations are possible within the range in which rotational motion is transmitted as twisting of the twisted string.

[0085] According to one embodiment of the present disclosure, the twist string (220) may include at least one of a wire, fiber, or filament in which a plurality of strands are arranged in parallel and formed integrally. Here, "a plurality of strands are arranged in parallel and formed integrally" may include a state in which individual strands are arranged side by side or bundled together in an initial state, and then twisted together by rotation to function as a single driving string group. For example, the twist string (220) may be implemented as a metal wire bundle, a polymer fiber bundle, a high-strength filament group, a carbon nanotube-based fiber, a conductive polymer fiber, or a composite structure thereof. The number, diameter, effective length for twisting, sheath thickness, and material of the strands may be selected according to the required output, allowable shrinkage, repeatability, and whether current is applied.

[0086] Additionally, the twist string (220) may be a structure in which a conductive coating layer is formed on a non-conductive substrate, or it may be a structure in which the entire structure is made of a conductive material. For example, the center may be formed of a high-strength fiber, and the outer circumference may be formed of a metal thin film, a conductive polymer layer, or a carbon-based conductive layer. In this case, the twist string (220) may function as a mechanical tension member and simultaneously provide an electrical path through which current can be applied. Therefore, in the present disclosure, the twist string may be understood not as a simple tension member, but as a multi-functional linear member capable of participating in both mechanical driving and the formation of an electric magnetic field.

[0087] According to one embodiment of the present disclosure, the twist section (240) of the twist string (220) may be disposed inside the housing (410) of the fluid core (400). More specifically, the housing (410) may form a sealed space in which fluid is contained, and the twist section (240) may be located within the sealed space. On the other hand, the end or output section of the twist string (220) may pass through the housing (410) and extend outward, and may be coupled to a variable stiffness structure (300) outside the housing (410). Accordingly, a separate arrangement may be possible in which the core section where the twisting operation occurs is maintained within the fluid environment, and tension transmission to the structure is performed outside the housing.

[0088] In the present disclosure, the housing (410) may include a cylindrical, polygonal, slotted, tubular, or chambered structure, and may have an inlet and an outlet formed for inserting and withdrawing the twisted string (220). Additionally, the inlet and outlet may have a seal structure, a packing structure, or a low-friction guide formed therein to suppress external leakage of fluid while allowing relative movement of the string. Accordingly, the internal arrangement of the twisting section (240) within the housing is not limited to the concept of simply immersing the string in fluid, but may include a structural arrangement that simultaneously considers the twisting, contraction, penetration, guidance, and fluid sealing of the string.

[0089] According to one embodiment of the present disclosure, a through-hole may be formed in the housing (410) to allow a twisted string (220) to pass between the inside and the outside. At this time, the through-hole may further be provided with a sealing structure to allow relative movement of the twisted string (220) while suppressing external leakage of the magnetic fluid (420). Here, the sealing structure may include a packing, a seal member, a lip seal, an O-ring, a sleeve-type seal, a low-friction bushing, or a combination thereof. Thus, a structure may be formed in which the fluid environment formed inside the housing (410) is maintained while the twisting and contracting movements of the twisted string (220) are not hindered.

[0090] According to one embodiment of the present disclosure, the sealing structure of the through-hole may include a dynamic sealing unit configured to maintain airtightness even when rotational movement and linear movement of the twist string (220) occur simultaneously. For example, the dynamic sealing unit may include an elastic bellows structure, a low-friction rotary sliding seal structure, a lip seal structure, a sleeve seal structure, or a combination thereof. By such a structure, the magnetic fluid (420) environment inside the housing (410) can be maintained while allowing repetitive twisting and contracting movements of the twist string (220).

[0091] Additionally, the dynamic sealing unit may be implemented with a guide member to maintain the center alignment of the twist string (220). For example, a guide member made of ceramic or low-friction polymer material may be placed in combination with the seal structure, thereby reducing the possibility of local wear and fluid leakage near the penetration.

[0092] Additionally, a guide structure for aligning the path of the twist string (220) may be further formed in the above-mentioned through-hole. For example, the guide structure may include a guide hole, a ceramic or polymer-based guide member, a low-friction coating layer, or a curved guide surface. Accordingly, direct friction between the twist string (220) and the edge of the housing (410) can be suppressed, and local wear during repeated operation can be reduced. The sealing and guide structure of such through-hole may be formed at least one of the upper end, lower end, or both ends of the housing (410), and a structure in which a plurality of seal elements are arranged in series in a single through-hole is also possible.

[0093] According to one embodiment of the present disclosure, the fluid contained in the fluid core (400) may include a magnetic fluid, and the robot drive device (600) may further include a magnetic field generating unit (430) that applies a magnetic field to the magnetic fluid inside the housing (410). Here, "magnetic fluid" may broadly refer to a fluid in which magnetic particles or magnetic response particles are dispersed within a base oil or a liquid medium. The magnetic fluid may include nano-sized or micro-sized magnetic particles, and a surfactant layer or a protective layer for dispersion stability may be formed on the surface of the particles. Additionally, the magnetic field generating unit (430) may include an electromagnetic coil disposed on the inner or outer side of the housing (410), a magnetic field forming unit disposed adjacent to the housing, or a current application structure for a conductive twisted string (220).

[0094] When the magnetic field generating unit (430) is positioned on the outer side of the housing (410), an annular coil or a split coil may be positioned along the circumference of the housing (410), and the distribution of magnetic fluid inside the housing may change depending on the magnitude or direction of the current applied to the coil. Meanwhile, when the magnetic field generating unit (430) is positioned on the inner side of the housing, local magnetic field control may be possible at a location closer to the internal flow space. Accordingly, the magnetic field generating unit (430) can be understood as an electrical actuation means for changing the position, concentration distribution, flow resistance, or viscosity state of the magnetic fluid, and the fluid core of the present disclosure may include a functional structure in which a mechanical housing and an electrical magnetic field generating unit are combined.

[0095] According to one embodiment of the present disclosure, a magnetic fluid (420) contained in a fluid core (400) can perform a lubricating function by forming a fluid film on the outer surface of a twisted string (220). More specifically, when current is applied to a conductive twisted string (220) and a magnetic field is formed around it, magnetic particles inside the magnetic fluid (420) can be attracted toward the surface of the twisted string (220) where the magnetic field strength is relatively high. Accordingly, a fluid layer concentrated with magnetic particles can be formed on the outer surface of the twisted string (220), and said fluid layer can function as a lubricating film in the contact area between adjacent strands or between the string and the inner wall of the housing (410).

[0096] In the present disclosure, the fluid film may be maintained on the surface of the twisted string (220) by magnetic attraction formed by the application of current to the external coil-type magnetic field generator (430) or the conductive twisted string (220). While conventional lubricants tend to detach from the contact surface due to centrifugal force during high-speed rotation or be extruded under high-load conditions, the magnetic fluid (420) may be promoted to return to the string surface by magnetic bonding force. For example, even if the fluid film on the outer surface is locally thinned or temporarily destroyed by friction during the twisting motion of the twisted string (220), the magnetic fluid (420) in an adjacent area may move to that area by the magnetic field distribution around the string to restore the fluid film. This phenomenon can be understood as a characteristic in which the fluid film is restored without external intervention even after frictional damage, i.e., a self-restoring lubrication characteristic.

[0097] These self-restoring lubrication characteristics can be controlled according to the magnitude of the current applied to the twist string (220). For example, if the current increases, the magnetic field strength increases, and accordingly, the magnetic particle gathering force to the string surface increases, so that a thicker fluid film can be formed. On the other hand, if the current decreases or is cut off, the magnetic bonding force weakens, and the degree of dispersion of magnetic particles can become relatively uniform. Therefore, the control unit (500) can indirectly control the thickness or distribution characteristics of the fluid film by adjusting the current applied to the twist string (220). Such a configuration can contribute to reducing friction between strands due to repetitive twisting and untwisting cycles, suppressing wear of the twist string (220), and improving the repetitive durability life of the string actuator module (200). In addition, since the magnetic fluid (420) inside the housing (410) can perform the lubrication function and restore itself without a separate external lubrication supply device, the structural simplicity and maintenance efficiency of the fluid core (400) can be increased.

[0098] According to one embodiment of the present disclosure, the magnetic fluid (420) may have a characteristic in which the viscosity of the fluid changes depending on the strength of the magnetic field applied by the magnetic field generating unit (430). More specifically, when the strength of the magnetic field is relatively low, the magnetic particles inside the magnetic fluid (420) are dispersed relatively freely, so that the fluid flow resistance can be kept low. On the other hand, when the strength of the magnetic field is relatively high, the magnetic particles may be arranged along magnetic field lines or form clusters, and accordingly, the shear resistance or flow resistance inside the fluid may increase.

[0099] These viscosity change characteristics can be utilized as a means to actively control fluid resistance to the movement of the twist string (220) inside the fluid core (400). For example, when the current applied to the magnetic field generator (430) is low, the flow resistance of the magnetic fluid (420) in the first flow space (450) is minimized, so that the twisting and contracting movements of the twist string (220) can be performed quickly. On the other hand, when the current applied to the magnetic field generator (430) is high, the viscosity of the fluid increases, and the damping force on the movement of the twist string (220) can increase. This increase in damping force can be utilized to suppress rapid changes in the speed of the twist string (220) or to convert external shock or vibration energy into shear stress of the fluid and absorb it. Accordingly, the magnetic field generating unit (430) can function as an electromagnetic damping means to dampen the movement of the twist string (220) without using a physical friction brake.

[0100] The control unit (500) can change the damping characteristics of the fluid core (400) in real time by adjusting the magnitude of the current applied to the magnetic field generator (430) in milliseconds. For example, when the robot drive unit (600) detects an external shock, the control unit (500) can instantaneously increase the current to the magnetic field generator (430) to increase fluid viscosity, thereby damping the shock energy transmitted to the twist string (220) and the variable stiffness structure (300) at the fluid level. On the other hand, in sections where high-speed driving is required, the current can be minimized to lower the fluid flow resistance and maximize the response speed of the string actuator module (200). Thus, the fluid core (400) can perform lubrication, cooling, and damping functions integrally by a single fluid medium, and the relative weight of these functions can be dynamically adjusted by the combination of the magnetic field generator (430) and the control unit (500).

[0101] According to one embodiment of the present disclosure, the housing (410) may be formed of a material selected to accommodate a magnetic fluid (420) inside, while allowing the magnetic field generated by the magnetic field generator (430) to act into the housing. For example, the housing (410) may be implemented as a non-magnetic metal, a non-conductive resin, an engineering plastic, a composite material, or a laminated structure thereof. In this case, by using a non-magnetic metal or a non-conductive resin, the magnetic field generated by the coil-type magnetic field generator (430) may not be excessively shielded by the housing (410).

[0102] Additionally, the housing (410) does not need to be formed entirely of the same material, and the area requiring magnetic field transmission and the area requiring structural rigidity may be configured to have different materials or different thicknesses. For example, the perimeter area corresponding to the coil may be formed with a relatively thin non-magnetic wall structure, and the area near the penetration or fastening may be formed with a relatively thick reinforcing structure. As another example, an opening, a thin wall, or a separate non-metallic insert may be formed in a part of the housing (410) to consider magnetic field transmission efficiency. Thus, the housing (410) can be understood not as a simple container structure, but as a multi-functional structure that considers fluid reception, string guidance, magnetic field transmission, and mechanical support together.

[0103] According to one embodiment of the present disclosure, the twisted string (220) may be formed of a conductive material or may include a structure having a conductive coating layer formed on its outer circumference. Additionally, the magnetic field generating unit (430) may include a power supply unit that applies current to the twisted string (220). In this case, the twisted string (220) itself forms part of the current path, and as a magnetic field is generated around it, the magnetic fluid may be concentrated or redistributed around the twisted string (220). Here, the power supply unit that applies current to the twisted string (220) may include a rotating electrode structure capable of maintaining an electrical connection in a rotating state, and the power supply unit that applies current to the twisted string (220) may include a slip ring, brush, rotating electrode, conductive end, or flexible wire connection structure electrically connected to a rotating shaft or a rotating member (230). Accordingly, an embodiment including a conductive twisted string may provide a magnetic field generating structure using the string itself in addition to a separate external coil.

[0104] Additionally, the conduction path of the conductive twisted string can be implemented as a single core wire structure, a multi-core wire structure, a coated electrode structure, or an outer coating structure. In this case, the twisted string (220) can function as a tensile material mechanically and as a conductor for forming a magnetic field electrically. Such a configuration may be advantageous for locally inducing interaction with a magnetic fluid and may be used in combination with a separate coil placed on the outer periphery of the housing. Accordingly, the present disclosure can encompass both a coil-type magnetic field generating structure on the outer periphery of the housing and a current-applied magnetic field generating structure for the conductive twisted string.

[0106] FIG. 4 is another cross-sectional view showing a fluid core according to one embodiment of the present disclosure in more detail.

[0107] According to one embodiment of the present disclosure, the fluid core (400) may include a housing (410), a magnetic fluid (420) contained within the housing, and a plurality of spaces formed within the housing and a flow path structure connecting them. Here, the term "fluid core" does not simply mean a container for containing fluid, but may mean the entire functional structure including a first flow space where at least a portion of the twist string (220) is located, a storage space that secures a relative amount of fluid storage, a second flow space formed on the housing wall side, and a flow path connecting each space. That is, the fluid core (400) is not limited to a single chamber structure where the fluid remains only in a stationary state, but may include an internal flow structure designed to allow the fluid to move or be redistributed between spaces having different positional characteristics.

[0108] In the present disclosure, "first flow space" may refer to a space formed closest to the twist string (220) while surrounding the twist section (240), and "storage space" may refer to a relatively spacious space for securing the amount of fluid to be supplied to the first flow space. Additionally, "second flow space" may be understood as a space formed on the housing wall side, spaced apart from the first flow space, for heat exchange with the housing wall, fluid redistribution, or forming a wall-side retention area. "Flow path" refers to a passage connecting these spaces to one another and may include a straight passage, an annular passage, a branched passage, a microchannel, or an opening. Accordingly, the fluid core of the present disclosure may have a multi-region fluid structure in which the area around the twist string, the storage section, and the wall-side area are structurally separated yet functionally interconnected.

[0109] According to one embodiment of the present disclosure, an internal guide structure may be further formed within the housing (410) to partition a storage space (440), a first flow space (450), and a second flow space (470) from one another. Here, the internal guide structure may include a partition wall, a guide wall, a separator plate, a rib, a channel forming part, a spacer, or a protrusion as a structural element for establishing a fluid retention area or movement path. For example, by arranging a separator plate extending along the outer circumference of a twisted section (240), the first flow space (450) in the center adjacent to the twisted section (240) and the second flow space (470) on the housing wall side may be separated from each other.

[0110] Additionally, the storage space (440) may be formed by a structure in which a part of the housing (410) is locally extended, a separate pocket structure, or a chamber-shaped protrusion. The first flow path (460) and the second flow path (480) may be formed as an opening, slit, channel, or through passage to connect these spaces. Accordingly, the interior of the fluid core (400) is not limited to a simple structure in which fluid is filled in a single cavity, but may include a multi-region flow structure in which the twisted section adjacent area, the storage area, and the wall-side area are structurally partitioned.

[0111] According to one embodiment of the present disclosure, the central area (ZONE 1) and wall-side area (ZONE 2) illustrated in FIG. 4 may be understood as being separated for convenience of explanation. For example, the central area closer to the twist section (240) may correspond to the first flow space (450), the outer area (wall-side area) closer to the inner wall of the housing (410) may correspond to the second flow space (470), and the buffer area, which is an extended part of the housing illustrated in the lower center of FIG. 4, may correspond to the storage space (440). However, since the concentration, viscosity, dispersion state, or residence rate of the actual fluid may vary depending on magnetic field conditions, fluid composition, current state of the twist string (220), temperature, or flow resistance, it is not limited to the requirement that a specific concentration must be maintained in a specific space.

[0112] According to one embodiment of the present disclosure, the housing (410) may include a storage space (440), a first flow space (450), and a first flow path (460) connecting the storage space (440) and the first flow space (450). The storage space (440) may be formed as an area capable of accommodating a relatively large amount of magnetic fluid (420) and may be formed on one side of the housing (410), an extension around the housing, or an end of the housing. On the other hand, the first flow space (450) may be formed in a shape surrounding the twist section (240) to form the area closest to the outer surface of the twist string (220). The first flow path (460) may fluidly connect the two spaces so that fluid can reach from the storage space (440) to the first flow space (450).

[0113] In the above structure, the storage space (440) can function as a buffer or supply area for the fluid, and the first flow space (450) can function as a core flow area that substantially corresponds directly to the twist of the twist string (220). The cross-sectional area, length, number, and placement location of the first flow path (460) can be selected considering the fluid supply amount, flow resistance, and redistribution velocity. For example, the first flow path (460) may be a single large opening or a structure in which a plurality of micro passages are formed in parallel. Additionally, the storage space (440) may be placed on the same axis as the first flow space (450) or may be placed offset in the circumferential or radial direction of the housing. Thus, a configuration including the storage space (440), the first flow space (450), and the first flow path (460) can form the basic internal structure of the fluid core that allows the fluid to be supplied to the twist section or redistributed around the twist section.

[0114] According to one embodiment of the present disclosure, the housing (410) may further include a second flow space (470) formed on the housing wall side, spaced apart from the first flow space (450), and a second flow path (480) connecting the first flow space (450) and the second flow space (470). The second flow space (470) may be formed in an area close to the housing wall to form a peripheral flow area distinct from the first flow space (450) that is in direct contact with the twist section (240). The second flow path (480) may serve as a passage connecting the first flow space (450) and the second flow space (470), thereby providing a fluid movement path between the two spaces. In this case, the second flow path (480) may be implemented as a straight channel, an annular connection, a radial passage, a plurality of individual connections, or an opening in a partition wall.

[0115] The reason for separately forming the second flow space (470) can be understood as functionally separating the fluid area adjacent to the twist string (220) from the fluid area on the housing wall side, and allowing them to communicate with each other as needed. That is, the first flow space (450) is a region directly corresponding to the twist section (240), and the second flow space (470) may be an outer region where thermal or fluid interaction with the housing wall is relatively emphasized. Through this dual flow space structure, it is possible to configure a fluid core that can simultaneously consider local flow near the twist section and fluid retention or circulation on the housing wall side. In addition, the shape and arrangement of the second flow path (480) can serve as a means to control the resistance to fluid movement between the first flow space (450) and the second flow space (470), and accordingly, the temporal change characteristics of the fluid distribution can also be designed.

[0116] According to one embodiment of the present disclosure, a heat exchange jacket (490) may be coupled to the outside of the housing (410) to be in thermal contact with the second flow space (470). Here, "heat exchange jacket" may broadly refer to a heat transfer member formed in contact with the outer wall of the housing and may include a jacket-type structure having a refrigerant flow path, a cooling sleeve structure, a channel block structure, an external heat dissipation fin structure, or an external heat transfer plate structure. The heat exchange jacket (490) may be formed along the entire length of the housing (410) or may be partially formed only in a specific section corresponding to the second flow space (470). For example, in a jacket-type structure through which liquid refrigerant flows, heat may be transferred through the contact surface between the outer wall of the housing and the jacket, and in an air-cooled structure, heat may be released to the outside through a heat dissipation surface in contact with the outside air.

[0117] As another example, a plurality of heat exchange jackets (490) may be spaced apart along the length of the housing to form a section-by-section heat management structure. Accordingly, the heat exchange jacket (490) of the present disclosure is not limited to a single shape or a single cooling method, but may include any suitable heat exchange structure that is thermally coupled with the outer wall of the fluid core (400).

[0118] Additionally, since the second flow space (470) is formed on the housing wall side, the magnetic fluid (420) located in the second flow space (470) can form a more direct thermal linkage relationship with the heat exchange jacket (490) with the housing wall in between. Therefore, the heat exchange jacket (490) can be understood as a structure that performs heat transfer indirectly through the fluid region on the housing wall side, even if it is not configured to be in direct contact with the twist section (240). Such a configuration can form a multi-layer heat transfer structure in which the first flow space (450), the second flow space (470), the second flow path (480) inside the fluid core, and the heat exchange jacket (490) on the outside of the housing are arranged together.

[0119] According to one embodiment of the present disclosure, the magnetic field generating unit (430) may be positioned to correspond to the housing (410) of the fluid core (400), and more specifically, may be positioned to correspond to the first flow space (450), the storage space (440), the second flow space (470), or at least one of these. For example, if an annular coil is formed along the outer circumference of the housing, a magnetic field may be formed at a position adjacent to the first flow space (450), and as another example, if a plurality of coils divided along the length direction of the housing are arranged, local magnetic fields corresponding to each of the storage space (440), the first flow space (450), and the second flow space (470) may be formed.

[0120] In addition, when a structure is employed to apply current to a conductive twisted string (220), a magnetic field formed around the twisted string (220) itself can act directly on the magnetic fluid (420) of the first fluid space (450). At the same time, when a coil-shaped magnetic field generator (430) on the outside of the housing is used together, the magnetic field at the center of the string and the magnetic field around the housing can be superimposed or applied in stages. Accordingly, the fluid core (400) of the present disclosure can be understood not as a simple fluid storage structure, but as an electro-mechanical-fluid combined structure in which the arrangement of the internal fluid space and the arrangement of the magnetic field generator correspond to each other. Furthermore, various embodiments of the fluid core can be realized through a combination of the arrangement position of the magnetic field generator (430), the driving current, the coil shape, and the fluid space structure.

[0121] According to one embodiment of the present disclosure, the flow of magnetic fluid (420) within a fluid core (400) can be induced by the interaction of a temperature distribution and a magnetic field distribution. More specifically, when heat is generated by the twisting motion of a twist string (220) or the application of current, the magnetic fluid (420) in the first flow space (450) adjacent to the twist section (240) may have a higher temperature than the surrounding area. The magnetic susceptibility of the magnetic fluid (420) may have a physical characteristic of decreasing as the temperature rises. Accordingly, the magnetic response of the magnetic fluid (420) located in the high-temperature region may be relatively weak, and the magnetic response of the magnetic fluid (420) located in the low-temperature region may be maintained relatively strong.

[0122] When a magnetic field is applied by a magnetic field generator (430) while there is a difference in magnetic susceptibility according to temperature, the magnetic fluid (420) in the low-temperature region, which has a relatively high magnetic susceptibility, can be attracted in the direction of the stronger magnetic field. As a result, the fluid in the high-temperature region is pushed away in the direction where the magnetic attraction is weak, and the fluid in the low-temperature region can take its place. This process can form a flow pattern in which the magnetic fluid (420) circulates spontaneously without an external pump or a separate flow driving source. In the present disclosure, this phenomenon may be referred to as "thermomagnetic convection," and the thermomagnetic convection may refer to spontaneous fluid circulation induced by the inherent magnetic susceptibility temperature dependence of the magnetic fluid under conditions of coexistence of a temperature gradient and a magnetic field distribution.

[0123] According to one embodiment of the present disclosure, fluid circulation by thermal magnetic convection may be formed along a flow path comprising a first flow space (450), a second flow path (480), a second flow space (470), and a first flow path (460). For example, a magnetic fluid (420) heated by heat generated in the first flow space (450) adjacent to the twist section (240) may have its magnetic susceptibility reduced and be pushed away from the center of the magnetic field, and may move through the second flow space (470) on the housing wall side through the second flow path (480). In the second flow space (470), the fluid temperature may be lowered by heat exchange with the housing (410) wall or the heat exchange jacket (490), and the magnetic fluid (420) with the lowered temperature may have its magnetic susceptibility relatively restored and be drawn back toward the first flow space (450) by the magnetic field. Accordingly, a circulation path leading from [first flow space (450) → second flow space (480) → second flow space (470) → first flow space (460) → storage space (440) → first flow space (450)] can be formed.

[0124] Due to the above-described thermomagnetic convection-based fluid circulation structure, heat generated in the twist section (240) can be continuously transported to the housing wall side by the magnetic fluid (420) and released to the outside through the heat exchange jacket (490) on the outside of the housing. Therefore, internal heat management of the fluid core (400) can be performed autonomously without a separate fluid pump, piping, or flow drive device. This can improve the structural simplicity and reliability of the robot drive device (600), and in particular, prevent a decrease in driving efficiency by suppressing the temperature rise of the twist string (220) and the magnetic fluid (420) under continuous driving or high-load driving conditions. In addition, since the strength of thermomagnetic convection can be indirectly changed by adjusting the driving current of the magnetic field generator (430), adaptive heat management can be achieved by strengthening the circulation flow in the high-power section and suppressing the circulation flow in the low-power section.

[0126] FIG. 5 is a schematic diagram showing a laminated structure of a variable stiffness structure according to one embodiment of the present disclosure.

[0127] According to one embodiment of the present disclosure, the variable stiffness structure (300) may be a structure that performs shape maintenance, support, bending, or deformation in response to an external load or the contraction force of a string actuator module (200). The variable stiffness structure (300) may not be a simple fixed stiffness frame, but may refer to a structure in which effective stiffness can be changed based on a plurality of stacked members (320) and a restraining structure that controls the relative movement state between them. Here, "stiffness" may be understood as a concept including at least one of bending resistance, compression resistance, torsional resistance, or local deformation resistance, and the "variable stiffness structure" may not be limited to a structure in which the resistance value is maintained at a single fixed value, but may encompass a structure capable of switching between at least two or more states. The above variable rigidity structure (300) can be implemented as a beam type, link type, plate type, finger type, joint assist type, or exoskeleton support type structure, and can be directly coupled to the driving target part of the robot or placed as part of the robot driving device (600) through a separate connection part.

[0128] In the present disclosure, the term "laminated structure" does not necessarily mean a structure in which flat plates are stacked only in a vertical direction, but may include a state in which a plurality of plate-shaped members, sheet-shaped members, ribbon-shaped members, thin composite materials, flexible films, or thin, long strip-shaped members are arranged in an overlapping manner. Additionally, each laminated member (320) may have the same material and shape, or may be composed of heterogeneous laminates with different thicknesses, materials, widths, surface friction coefficients, or bending characteristics. For example, a structure in which a metal or composite plate with high rigidity is placed in the center and a relatively flexible polymer sheet is placed on the outer side is possible, or a structure in which the entire laminated member (320) is made of the same elastic sheet is also possible. Accordingly, the variable rigidity structure (300) of the present disclosure can be realized in various laminated structures depending on the robot's operating direction, required load, deformation mode, and mounting space.

[0129] According to one embodiment of the present disclosure, a stacked member (320) may be arranged to extend along the contraction direction of a twisted string (220). Here, "extending along the contraction direction" may include a state in which the long side direction or the main extension direction of the stacked member (320) substantially coincides with the direction of transmission of the contraction force generated by the string actuator module (200), or has an angle of inclination within a certain range with respect to it. For example, the stacked member (320) may be extended in a straight line, formed as a curved or partially curved shape having a specific curvature, stacked side by side along a single straight axis, or stacked along an arc-shaped frame. Accordingly, the stacked member (320) may be arranged in a curved state to correspond to a curved driving target part such as a robot finger, or may be stacked straight along a link-shaped member.

[0130] Additionally, the laminated member (320) may be implemented as a plate-type member or a sheet-type member. Here, "plate-type member" may refer to a relatively independent plate-shaped member having its own thickness and bending rigidity, and "sheet-type member" may refer to a thinner and more flexible membrane-type or film-type member. However, rather than being strictly distinct concepts, the two can be understood as relative distinctions based on the member thickness, elastic modulus, shape retention ability, and the material used. In this way, the present disclosure can broadly encompass the material and shape of the laminated member (320) while maintaining the basic technical concept of changing structural characteristics by changing the relative movement state between multiple members.

[0131] According to one embodiment of the present disclosure, the laminated members (320) can form a laminated structure in which they are arranged substantially parallel to each other. For example, a plurality of plate-shaped members may be arranged so as to be in close contact without any gap in the vertical direction, and as another example, a structure may be implemented in which a plurality of sheet-shaped members are loosely overlapped in an initial state and then come into close contact with each other according to a change in the constraint state. In addition, the laminated members (320) may be formed not only as a simple single-row laminated structure but also as a multi-laminated structure in which two or more laminated bundles are arranged in parallel. In this case, each laminated bundle may be compressed simultaneously by the same tension transfer unit or may be controlled independently by different constraint units. Accordingly, the variable stiffness structure (300) is not limited to a single simple beam shape but can be extended to a multiple beam-shaped structure, a frame-shaped structure, or a grid-shaped structure.

[0132] The arrangement of the stacked structure may vary depending on the deformation mode required by the robot drive unit (600). For example, if only unidirectional bending is required, a single stacked structure with parallel stacking may be used, and if torsional resistance or multi-axial stiffness change is required, a multiple stacked structure distributed in the circumferential direction may be employed. Additionally, a surface roughness layer, an insulating layer, a coating layer, a micro-protrusion structure, or a fluid-friendly / hydrophobic surface treatment may be added between the stacked members (320) to increase friction. These additional structures are combined with the restraining member (310) described later to allow for more precise setting of the relative movement resistance between the stacked members. Accordingly, the present disclosure may encompass a wide range of embodiments including the arrangement shape, number, surface condition, and presence of auxiliary layers of the stacked structure.

[0133] According to one embodiment of the present disclosure, the laminated member (320) may be formed from a metal sheet, a composite sheet, a polymer film, a fiber-reinforced sheet, an elastomer sheet, or a composite laminate thereof. Each laminated member (320) may be made of the same material, but may also form a heterogeneous laminated structure in which a member with high rigidity and a member with relatively flexibility are alternately arranged. Accordingly, the initial bending characteristics, restraint characteristics during compression, and repetitive driving durability of the entire structure can be set to suit the design purpose.

[0134] Additionally, a surface structure for controlling friction characteristics may be further formed on the surface of the laminated member (320). For example, a surface roughness layer, a pattern processing layer, a micro-protrusion structure, an insulating coating layer, a conductive coating layer, or a low-friction coating layer may be formed. Accordingly, the relative movement resistance between the laminated members can be controlled, and the contact state or slip resistance during the operation of the restraint member (310) can be controlled more precisely. Therefore, the laminated structure of the present disclosure may go beyond a simple plate laminated structure and include a variable stiffness structure in which the material and surface condition are designed together.

[0135] According to one embodiment of the present disclosure, a variable stiffness structure (300) can be driven by the contraction force of a string actuator module (200). Here, "driven" may include not only the movement of the entire structure, but also the structure undergoing bending deformation, providing support in a specific direction, or changing its posture in conjunction with changes in the constraint state of the laminated members (320). For example, the end of the twist string (220) may be coupled to the end, middle, or tension transfer portion of the variable stiffness structure (300), and as the twist string (220) contracts, the entire laminated structure may be compressed or tensioned, thereby changing the shape and stiffness state of the structure. Additionally, if there are multiple string actuator modules (200), it is possible to selectively drive only a specific part of the structure or to drive the entire structure jointly by applying tension to the variable stiffness structure (300) at different locations.

[0136] Additionally, the coupling relationship between the variable stiffness structure (300) and the string actuator module (200) is not limited to a direct coupling. For example, the twisted string (220) may be indirectly connected to the laminated member (320) through a separate link, band, wrapping member, fastening frame, or compression plate. In this case, the amount of contraction of the string does not necessarily have to correspond 1:1 with the amount of displacement of the structure, and various mechanical transformation relationships may be formed depending on the link ratio, winding radius, connection position, and the initial shape of the laminated structure. Accordingly, the variable stiffness structure (300) of the present disclosure may be formed integrally with the string actuator module (200) or may be coupled via a kinematic transmission structure, and such coupling relationships may be understood within the scope of protection of the present invention.

[0138] FIG. 6 is a schematic diagram showing a restraining part according to one embodiment of the present disclosure.

[0139] According to one embodiment of the present disclosure, the restraining member (310) may be a component that changes the relative movement state between adjacent stacked members (320) constituting a variable stiffness structure (300). Here, "relative movement state" may broadly refer to the degree to which adjacent stacked members (320) slide, separate, or come into contact with each other, and the "restraining member" may include a mechanical, fluid, electrical, or composite structure that operates to allow, restrict, or partially restrict such relative movement. That is, the restraining member (310) is not limited to a single locking device and may include a structure that brings the stacked members into contact by depressurization, a structure that brings the members into contact by electrical attraction between electrode layers, or a tension transfer structure that induces compression in the stacking direction according to the contraction force of the string actuator module (200). Accordingly, the restraining member (310) of the present disclosure may be understood as a state switching means that changes the mechanical degrees of freedom of the stacked members (320).

[0140] In the present disclosure, the term "restraint" does not mean only when the stacked members (320) are completely fixed, but may also include a state of reducing relative slip, increasing frictional resistance, or restricting movement of only a portion of the structure. Additionally, the restraint member (310) may operate over the entire length, but may also be configured to be partially placed only in a portion of the structure to perform local stiffness control. For example, a differential restraint structure is possible in which a stronger restraint is applied to the base of the robot finger-shaped structure and a relatively weaker restraint is applied to the end. Thus, the restraint member (310) may be a means for collectively adjusting the stiffness of the entire structure, or a means for differentially setting characteristics by section or direction of the structure.

[0141] According to one embodiment of the present disclosure, the restraining member (310) may include a hermetic outer shell (330) surrounding the laminated members (320) and a pressure reduction source (340) for reducing pressure inside the hermetic outer shell (330). Here, "hermetic outer shell" may refer to an outer shell structure that surrounds the outer circumference of the laminated members (320) and forms a sealed space inside, and may include a flexible film-type outer shell, a tubular-type outer shell, a bellows-type outer shell, a laminate pouch-type outer shell, or a partially sealed chamber-type outer shell. The pressure reduction source (340) is a component that creates an internal pressure of the hermetic outer shell (330) lower than external atmospheric pressure and may include a vacuum pump, a suction pump, a negative pressure generator, a fluid pressure source, an electric pressure controller, or a pressure storage vessel. The pressure reduction source (340) may be directly connected to the outer shell or indirectly connected through a valve, a manifold, a flexible tube, or a pressure port.

[0142] In such a pressure reduction structure, when the internal pressure of the airtight outer shell (330) is lowered, the degree of contact between the laminated members (320) may increase. However, the present disclosure does not intend to limit this operating principle to a specific theory, and it is sufficient that the internal pressure condition of the outer shell is set in a direction in which the relative movement of the laminated members (320) is restricted. Additionally, the pressure reduction source (340) may continuously maintain negative pressure, or may apply negative pressure only at a specific point in time and then maintain the state through a check valve or a sealing structure. Accordingly, the pressure reduction drive type restraint (310) may include continuous drive type, pulse type, section-by-section select type, or step pressure type restraint structure.

[0143] According to one embodiment of the present disclosure, the restraining member (310) may include an electrode layer (350) disposed between adjacent stacked members (320) and a power supply unit that applies voltage to the electrode layer (350). Referring again to FIG. 6, a power supply unit that applies voltage to the electrode layer (350) is shown on the left side of FIG. 6. Here, the "electrode layer" is not necessarily limited to an independent metal plate and may include a conductive thin film, a conductive coating layer, a conductive fiber layer, a mesh-type electrode, a printed electrode, or a conductive pattern formed on the surface of a stacked member.

[0144] According to one embodiment of the present disclosure, the electrode layer (350) may be formed of a flexible conductive material capable of responding to repetitive bending or compressing motions. For example, the electrode layer (350) may include a conductive elastomer, a carbon nanotube-based flexible conductive film, a conductive polymer composite film, or a flexible conductive mesh structure. Accordingly, electrical continuity of the electrode layer (350) can be maintained even when relative deformation between the laminated members (320) is repeated.

[0145] According to another embodiment, the electrode layer (350) may be implemented as a structure in which a flexible substrate is laminated on a thin-film metal electrode, or as a conductive pattern structure printed on an insulating substrate. Accordingly, the electrode layer (350) of the present disclosure is not limited to a specific single material and may include various flexible electrode structures that satisfy both electrical application and mechanical flexibility in a repetitive driving environment.

[0146] The electrode layer (350) may be inserted between adjacent stacked members (320), formed directly on the surface of each stacked member (320), or disposed with a separate insulating substrate interposed therebetween. Additionally, the power supply unit may include a DC high-voltage source, a boost circuit, a pulse power supply, or an optional channel driving circuit, and may control the magnitude, polarity, application time, and application interval of the voltage applied to the electrode layer (350).

[0147] In the present disclosure, a restraint structure using an electrode layer (350) can be understood as changing the relative movement state by causing an electrical attractive force to occur between adjacent stacked members (320). However, the present invention is not limited to a specific electrical operating principle and can be interpreted as encompassing a structure in which the contact state, close contact state, or sliding resistance between adjacent members changes by the application of voltage. Additionally, the electrode layer (350) may be formed continuously over the entire stacking length, or it may be formed into multiple electrode sections divided in the length direction or width direction to perform partial restraint control. Accordingly, an embodiment including the electrode layer (350) can provide an electrically selectable stiffness control structure.

[0148] According to one embodiment of the present disclosure, when an electrode layer (350) is disposed between adjacent stacked members (320), an insulating structure may be further formed between the electrode layer (350) and the stacked members (320) or between adjacent electrode layers. Here, the insulating structure may include a dielectric layer, an insulating film, an insulating coating layer, a resin layer, a ceramic thin film, or an insulating adhesive layer. Accordingly, even if voltage is applied to the electrode layer (350), unintentional short circuits between adjacent structures can be suppressed and electrical stability can be improved.

[0149] Additionally, the insulating structure may be formed continuously along the entire stacking length, or it may be formed partially only in a selected section where the electrode layer (350) is disposed. For example, an insulating coating layer is formed on at least one of the two surfaces of the stacking member (320), and an electrode layer (350) is disposed thereon. Accordingly, the electrode layer-driven restraint structure of the present disclosure may include an electromechanical composite structure in which the electrode layer (350) and the insulating structure are combined.

[0150] According to one embodiment of the present disclosure, the restraining member (310) may include a tension transmission member that compresses the stacked members (320) in the stacking direction according to the contraction force of the string actuator module (200). Here, "tension transmission member" may refer to a mechanical transmission structure that converts the contraction or tension state of the twisted string (220) into a compressive force of the stacked members (320), and may include a tension band, a tension cable, a link member, a wrapping member, a tightening plate, a cam structure, a slider, a clamp frame, or a tapered compression structure. For example, a structure is possible in which the end of the twisted string (220) is connected to a tension band that wraps around the outer circumference of the stacked structure, and as the twisted string (220) contracts, the tension band surrounds and tightens the stacked members (320). As another example, a structure is also possible in which the tension of the twisted string (220) is transmitted to the compression plate through a link, and the compression plate presses the stacking member (320) in the stacking direction. Accordingly, the tension transmission part can function as a bridge structure that mechanically connects the string actuator module (200) and the restraining part (310).

[0151] The tension transfer unit may be used alone or in combination with the pressure-reducing or electrode-type restraint structure described above. For example, a composite structure is possible in which basic contact is formed by a pressure-reducing source (340) or an electrode layer (350) in the initial state, and when additional stiffness increase is required, a tension transfer unit linked to string contraction further compresses the laminate. Such a structure allows the operating source of the restraint unit (310) not to be limited to a single element, but to include an embodiment in which multiple operating mechanisms are combined complementarily.

[0152] According to a more specific embodiment, the restraining member (310) may be implemented as a hybrid restraining structure comprising a pressure-reducing restraining structure by a pressure-reducing source (340) and an electric restraining structure by an electrode layer (350). For example, basic contact between the stacked members (320) is formed by the pressure-reducing source (340), and if additional restraining force increase is required, voltage may be applied to the electrode layer (350). As another example, the pressure-reducing structure and the electrode structure may operate simultaneously or sequentially to form different restraining states.

[0153] According to one embodiment of the present disclosure, a variable stiffness structure (300) may be configured to switch between a first state in which relative sliding between adjacent laminated members (320) is allowed and a second state in which relative sliding is restricted. Here, the "first state" may mean a state in which a relatively large degree of relative movement freedom is granted between adjacent members, such that the laminated members (320) can move independently or loosely. On the other hand, the "second state" may mean a state in which the degree of contact and restraint between adjacent members is increased, so that the entire laminate moves as a more integrated structure. In the present disclosure, this distinction between states is not defined by specific numerical values ​​or absolute stiffness values, but is understood as a state in which the degree of relative movement allowance within the same structure is distinguished from one another.

[0154] The transition between the first state and the second state can be achieved by the operation of the restraint unit (310). For example, the state of the structure may change depending on whether the depressurizing source (340) is driven, the magnitude of the voltage applied to the electrode layer (350), or the magnitude of the string tension transmitted to the tension transmission unit. In addition, when multiple restraint mechanisms are used in combination, a state in which only one restraint mechanism operates may be defined as the first state, and a state in which two or more restraint mechanisms operate simultaneously may be defined as the second state. Accordingly, the first state and the second state of the present disclosure are not limited to simple dichotomous states, but can be used as concepts representing representative states with different degrees of structural restraint.

[0155] According to one embodiment of the present disclosure, the variable stiffness structure (300) may further have an intermediate constraint state between a first state and a second state. Here, "intermediate constraint state" may mean a partial constraint state in which relative sliding between the laminated members (320) is neither completely free nor completely restricted. For example, if the depressurizing source (340) is operated only at a low pressure level, if only a partial voltage is applied to the electrode layer (350), or if an intermediate level of tension is applied to the tension transfer part, the laminated structure may exhibit mechanical behavior intermediate between the first state and the second state. Additionally, an intermediate constraint state may be understood even if only a portion of the laminated length direction is selectively constrained. Thus, the intermediate constraint state may not be a single value, but may be a concept encompassing multiple stages or continuously variable constraint levels.

[0156] Such an intermediate constraint state allows the robot drive device (600) to have a transitional section between a fully flexible state and a fully constraint state, thereby enabling more precise state transitions in a single structure. For example, a first state may be selected in the initial approach section, an intermediate constraint state in the load application section, and a second state in the final support or fixing section. However, the present invention is not limited to a specific state transition sequence and may include a structure in which the first state, the intermediate constraint state, and the second state can be selected in any order according to the required operation by the control unit. Accordingly, an embodiment including an intermediate constraint state can provide an extended embodiment of a variable stiffness structure (300) capable of multi-stage or continuous state control beyond simple bipartite stiffness control.

[0158] According to one embodiment of the present disclosure, a plurality of string actuator modules (200) may be coupled to a single variable stiffness structure (300). Here, the "multiple string actuator modules" may be multiple modules having the same structure and the same output characteristics, or a set of heterogeneous modules having different lengths, different string diameters, different motor capacities, or different fluid core sizes. The multiple modules may be spaced apart along the longitudinal direction of the variable stiffness structure (300), dispersed along the periphery direction of the structure, or coupled in a symmetrical or asymmetrical structure. For example, two string actuator modules (200) may be placed on both sides of a single longitudinal structure, and as another example, three or more modules may be radially placed around a single articulated structure. In addition, not only is an embodiment in which multiple modules having the same output characteristics are arranged in parallel for a single structure possible, but an embodiment in which heterogeneous modules having different output ranges are mixed and arranged is also possible. Accordingly, the present disclosure may encompass a multi-drive structure in which a plurality of driving sources jointly drive a single structure.

[0159] In a multi-modular structure, each string actuator module (200) may operate together at the same time or may operate selectively depending on the required load or posture. Additionally, the multiple modules may all apply contraction force in the same direction to form a single large driving force, or they may form different tension directions at different locations to perform posture control, curvature control, or local support control of the structure. Accordingly, the multi-modular embodiment may provide a wider degree of driving freedom and control flexibility than a single-modular structure, and the present disclosure may include the entire combined structure of such multiple modules.

[0160] According to one embodiment of the present disclosure, the robot drive unit (600) may further include a control unit. Here, "control unit" may refer to an electronic or electrical control means that controls the operation of at least some of a plurality of string actuator modules (200), a variable stiffness structure (300), a fluid core (400), a magnetic field generator (430), and a restraining unit (310). The control unit may be configured to include at least a portion of the computing device (100) described in the present disclosure. The control unit may include one or more microcontrollers, processors, digital signal processors, power control circuits, communication circuits, drive drivers, or memory circuits, and may be implemented as a distributed control structure or a centralized control structure. For example, a hierarchical structure is possible in which local control nodes corresponding to each string actuator module (200) are provided and a higher-level controller coordinates the overall state, or a structure is possible in which a single central control unit integrates and controls all modules, the restraining unit, and the magnetic field generator.

[0161] The control unit can drive each string actuator module (200) individually. Here, "driving individually" may mean that independent current, voltage, speed, rotation angle, or torque commands can be assigned to each module. Therefore, even if multiple modules exist, they do not always operate under the same driving conditions, and the driving conditions of each module can be set differently by the control unit. Such an individual control structure can serve as the basis for the selective module driving, consensus control, sensor feedback control, and linkage control described later.

[0162] In addition, the control unit can collect status information of each driving module via wired or wireless communication and adjust the driving conditions of individual modules based on the collected information. Accordingly, the control unit can function not merely as a simple on / off switching means, but as a control platform that integrally considers the state quantities of multiple modules, the driving state of the fluid core, and the constraint state of the variable stiffness structure.

[0163] According to one embodiment of the present disclosure, the control unit may be configured to select the number of modules actually driven among a plurality of string actuator modules (200). Here, "selecting the number of modules driven" means that, rather than always activating all of the plurality of modules simultaneously, only some modules are activated or additional modules are activated in stages according to the required driving conditions. For example, in sections requiring a relatively low load or a small amount of deformation, only one or some modules may be driven, and in sections requiring a larger driving force or structural support, additional modules may be activated sequentially. Additionally, some modules may be kept in a standby state and activated only when specific conditions are satisfied.

[0164] The above selection criteria may be determined based on a pre-set reference value, sensor detection value, required posture, structural state, or external force conditions. For example, additional modules may be activated when the deformation amount of the structure exceeds a reference range, and some modules may be deactivated when the structure reaches a target position. Additionally, if an overload or abnormal condition occurs in a specific module, the number of active modules in the remaining modules may be changed. Accordingly, an embodiment for selecting the number of driving modules can provide a structural control method that implements resource allocation, load sharing, and stepwise driving in a multi-modular structure.

[0165] According to one embodiment of the present disclosure, a control unit may be configured to control the operation of a plurality of string actuator modules (200) by consensus using at least one of the position, velocity, current, or tension of the plurality of string actuator modules (200). Here, "consensus control" may refer to a control method that adjusts the plurality of modules to converge to a common target state or a mutually aligned state without accumulating errors independently of each other. For example, the rotation angle or linear contraction amount of each module may be controlled so that they do not differ excessively from each other, or the tension acting on each module may be controlled to be balanced within a specific range. In this case, a control structure may be formed that can suppress asymmetric deformation, excessive local load, or torsion of the structure that may occur during the process of multiple modules pulling a single structure.

[0166] Consensus control may be performed by centralized computation or distributedly as each module exchanges state information with one another. For example, each module may transmit its current position, speed, current, or tension information to the control unit, and the control unit may correct the driving commands of each module based on the average state of the entire group of modules, the target state, or the state of the priority module. As another example, a structure is also possible in which information is shared only among adjacent modules, so that local consensus gradually expands into overall consensus. Accordingly, the consensus control of the present disclosure is not limited to a single specific algorithm but can encompass various control methods that maintain the states of multiple driving modules in mutual consistency.

[0167] According to one embodiment of the present disclosure, the control unit may be configured to calculate the amount of contraction or output force of the string actuator module (200) using a model that includes an effective radius that changes according to the twisting state of the twist string (220). Here, "effective radius" may refer to the actual radius or equivalent radius of the string bundle formed as the twist string (220) is twisted. In the initial state, the strands may be arranged relatively loosely to form a first radius, and as the twisting progresses, the effective radius may change due to the rearrangement of the strands and volume conservation relationship. Accordingly, the amount of contraction or output force of the string may be calculated more precisely by an effective radius model that includes the degree of twist, current length, initial radius, number of strands, material, or empirical correction value, rather than by a simple model that assumes a fixed radius.

[0168] According to one embodiment of the present disclosure, the effective radius model used by the control unit (500) may include a relationship for calculating the effective radius based on the initial radius, initial length, and current contraction state of the twisted string (220). For example, assuming that the twisted string (220) is composed of a plurality of strands and that the volume of each strand is preserved before and after twisting, the axial length of the string bundle decreases as contraction progresses, while radial expansion may occur. Accordingly, the effective radius may have a value greater than or equal to the initial radius, and the effective radius may gradually increase as the amount of contraction increases.

[0169] As a more specific example, the control unit (500) has an initial radius , initial wire length , defining the effective length after the current twist as X, and based on the volume conservation assumption, the effective radius r It can be calculated as follows. In the above relationship, as X decreases, that is, as the twist progresses further and the string bundle becomes shorter, the effective radius r increases. Such an increasing effective radius can further increase the mechanical gain of the output tensile force relative to the motor torque, and accordingly, a greater output tensile force can be obtained from the same motor torque when the twist progresses further.

[0170] Additionally, the above effective radius model can also be reflected in the relationship between the contracted length and the rotation angle of the twist string (220). For example, in an ideal geometric model, the effective length X of the twist string (220) after contraction is It can be expressed as, where can mean the accumulated rotation angle by the driving source (210). If the effective radius r is not a constant fixed value but changes according to the contraction state, the non-linear change of the contraction amount and output tensile force can be predicted more precisely by substituting the variable radius into the above relationship. Accordingly, the control unit (500) can calculate the expected contraction amount or expected output tensile force from the rotation angle command of the driving source (210) by applying the above effective radius model in real time, and can perform closed-loop position control or force control based on this.

[0171] However, the above mathematical relationship corresponds to an example based on an ideal geometric model, and in actual implementation, differences may occur due to factors such as friction between strands, material elasticity, fluid resistance, changes in physical properties due to temperature, or residual deformation due to repeated use. To correct these differences, the control unit (500) may add empirical correction coefficients to the analytical model, store correction data in the form of a lookup table, or apply an online learning-based parameter update algorithm. Accordingly, in the present disclosure, the effective radius model is not limited to a specific single mathematical formula, but may refer to a model that includes various correction and update mechanisms based on geometric relationships grounded in the volume conservation assumption.

[0172] The above model may be implemented in the form of a mathematical formula, an empirical formula, a lookup table, or a combination thereof. For example, an analytical formula based on the assumption of volume conservation or geometric approximation may be used, and a correction table based on actual experimental data may be used. In addition, different model parameters may be assigned to each string actuator module (200), and even within the same module, parameters may be updated according to usage time, wear condition, or temperature conditions. Accordingly, an embodiment in which the control unit utilizes an effective radius model can provide a precision control structure that reflects the nonlinearity of string-based driving.

[0173] According to one embodiment of the present disclosure, the effective radius model used by the control unit (500) may further include a correction factor or correction function that reflects the non-ideal behavior of the twist string (220) in addition to a basic model based on a volume conservation relationship. For example, the correction factor may be defined in the form of a function or coefficient determined according to at least one of the degree of overlap between strands, the degree of friction or compression between strands, the viscous state of the magnetic fluid (420), the applied magnetic field strength, the temperature state, or the wear state due to repeated use. Additionally, the correction factor or correction function may be implemented in the form of an adaptive parameter that is updated based on experimental constants, empirical formulas, lookup tables, or sensor feedback.

[0174] Additionally, the effective radius model may be implemented in the form of an analytical formula, or as a hybrid model combined with a lookup table or an empirical correction function. According to another embodiment, the control unit (500) can update the correction factor in real time based on sensor detection values, thereby maintaining the accuracy of calculating the shrinkage amount and output force of the twist string (220). Accordingly, the effective radius model of the present disclosure is not limited to a simple geometric ideal model, but may include an adaptive control model that reflects non-ideal mechanical behavior and changes in the fluid environment.

[0175] According to one embodiment of the present disclosure, the robot drive device (600) may further include at least one of a tension sensor, a current sensor, a voltage sensor, a back EMF sensor, a temperature sensor, a structural deformation sensor, or an external force sensor. Each sensor may detect a state quantity related to a string actuator module (200), a variable stiffness structure (300), a fluid core (400), or a driving target part of the robot. For example, the tension sensor may detect a tensile force acting on a twisted string (220), and the current sensor and voltage sensor may detect an electrical state applied to a driving source (210) or a magnetic field generating part (430). The back EMF sensor may indirectly reflect the rotational state of the motor, and the temperature sensor may detect a thermal state around the housing (410), magnetic fluid (420), driving source (210), or structure. The structural deformation sensor can detect the curvature, displacement, compression amount, or strain of the laminated member (320), and the external force sensor can detect the external force acting on the robot drive device (600) or the drive target. Accordingly, the sensor structure of the present disclosure is not limited to single state detection by a single sensor, but may include a multi-sensor structure that collects multiple state quantities at different locations.

[0176] The sensor values ​​detected in this manner can be transmitted to the control unit and used to control a plurality of string actuator modules (200). Additionally, if necessary, the control unit can adjust not only the driving state of the driving source (210) but also the operating state of the restraining unit (310) or the driving condition of the magnetic field generating unit (430) based on the sensor detection values. For example, if the amount of structural deformation exceeds a reference value, the restraining state can be controlled to be changed, and if a temperature rise is detected, the driving condition of the magnetic field generating unit (430) or the operating state of the fluid core (400) can be adjusted.

[0177] Additionally, the linked control may be a sequential structure in which the control unit first determines the state of the restraint unit (310) and then adjusts the magnetic field generator (430) accordingly, or it may be a simultaneous structure in which the states of the restraint unit (310) and the magnetic field generator (430) are calculated simultaneously based on sensor detection values. For example, if the external force increases or the deformation of the structure increases, the control unit may be configured to switch the restraint unit (310) to a stronger restraint state and simultaneously change the driving conditions of the magnetic field generator (430). As another example, the conditions of the magnetic field generator (430) may be adjusted first according to the temperature or current state of the fluid core (400), and the state of the restraint unit (310) may be subsequently adjusted in conjunction with this. Accordingly, an embodiment including a sensor can serve as a basis for providing a closed-loop control structure to the robot drive device (600).

[0178] According to one embodiment of the present disclosure, a robot driving device (600) may include a restraining member (310) provided in a variable stiffness structure (300) and a magnetic field generating member (430) corresponding to a fluid core (400), and a control unit may be configured to change the driving conditions of the magnetic field generating member (430) in conjunction with the driving state of the restraining member (310). Here, "in conjunction" may mean that the two elements do not operate completely independently, but can be coordinated together by at least one common control condition, state table, transition rule, or linkage command. For example, when the restraining state of the structure is low, the magnetic field generating member (430) is maintained at a first driving condition, and when the restraining state of the structure is switched to a high state, the magnetic field generating member (430) may be changed to a second driving condition. The driving conditions may include current magnitude, coil activation interval, driving period, waveform, or voltage conditions.

[0179] According to one embodiment of the present disclosure, the control unit (500) can set the driving state of the restraint unit (310) and the driving condition of the magnetic field generating unit (430) in conjunction with a plurality of operation scenarios. Below, an example of coordinated control according to a representative operation stage in which the robot driving device (600) interacts with the external environment is described.

[0180] According to one embodiment of the present disclosure, in a high-speed approach or free motion section as a first operation step, the control unit (500) can maintain the restraining unit (310) in a first state (a flexible state where relative sliding is allowed), and in response, the current applied to the magnetic field generating unit (430) can be set to a first current level. The first current level may be a level that maintains the viscosity of the magnetic fluid (420) relatively low, and accordingly, the flow resistance of the twisted string (220) is minimized, thereby improving the response speed of the string actuator module (200). At this time, the variable stiffness structure (300) maintains a flexible state, thereby securing a margin for the structure to deform and absorb shock upon external contact.

[0181] According to one embodiment of the present disclosure, in the second operation step, during the external shock detection or collision response section, the control unit (500) can detect an increase in external force or a sudden change in structural deformation based on sensor detection values, and accordingly, while maintaining the restraining unit (310) in a first state, the current applied to the magnetic field generating unit (430) can be increased to a second current level higher than the first current level. At the second current level, the viscosity of the magnetic fluid (420) increases, and the damping force for the movement of the twist string (220) can increase, and accordingly, at least a portion of the external shock energy can be absorbed by the shear resistance of the fluid. The restraining unit (310) maintaining a flexible state may be intended to prevent structural damage as the variable stiffness structure (300) deforms in the direction of the impact. Therefore, in this step, a division of roles can be formed in which the fluid core (400) performs an energy absorption function and the variable stiffness structure (300) performs a cushioning function through shape deformation.

[0182] According to one embodiment of the present disclosure, in a third operation step, in a high-load support or high-precision position maintenance section, the control unit (500) may switch the restraining unit (310) to a second state (a rigid state in which relative sliding is restricted), and in response, the current applied to the magnetic field generating unit (430) may be set to a third current level. The third current level may be the same as or different from the second current level, and may be selected so that the fluid damping characteristics around the twist string (220) are in harmony with the rigid state of the structure. For example, if there are high-frequency micro-vibrations that are difficult to suppress structural vibrations in the rigid state of the restraining unit (310), the current level of the magnetic field generating unit (430) may be increased to complementarily filter the micro-vibrations with the damping force of the fluid core (400). On the other hand, if sufficient support force is secured only by the rigid state of the restraining unit (310), the current of the magnetic field generating unit (430) may be lowered to reduce energy consumption.

[0183] According to one embodiment of the present disclosure, the transition between the first operation step, the second operation step, and the third operation step may be determined by a sensor detection value, a preset state transition table, or real-time judgment logic by the control unit (500). For example, if the detection value of the external force sensor or the tension sensor exceeds a first threshold value, a transition from the first operation step to the second operation step may be triggered, and if the position of the driving target unit enters within the target range, a transition to the third operation step may be triggered. Furthermore, the operation steps are not necessarily transitioned only sequentially; they may transition in any order according to the judgment of the control unit (500), or additional operation steps corresponding to intermediate restraint states may be inserted. Accordingly, the linkage control of the present disclosure may include a multi-stage linkage control structure in which the state combination of the restraint unit (310) and the magnetic field generating unit (430) is not limited to a single fixed pattern but is adaptively determined according to the operation scenario.

[0184] Accordingly, the linked control embodiment of the present disclosure can provide a structure in which the mechanical stiffness control structure and the magnetic field control structure of the fluid core are not separated but are operated under a single integrated control system.

[0186] In addition, instructions or programs for controlling the robot drive device of the present disclosure may be stored on a non-transient computer-readable storage medium, and when said program is executed on one or more processors, said one or more processors may be enabled to collect said drive state information, issue drive commands, or perform consensus control. Accordingly, the technical concept of the present disclosure may be implemented not only as a method for controlling a robot drive device, but also in the form of a computer program, a storage medium storing said program, and a computing device executing said program. Furthermore, the embodiments of the present disclosure described above are not applied independently of each other, but may be combined and applied within a technically compatible range.

[0188] According to one embodiment of the present disclosure, a robot may include a driving target part that forms a skeleton or external shape and performs a specific movement, and a robot driving device (600) that provides driving force or support force to the driving target part. Here, "driving target part" may broadly refer to a joint, link, finger, exoskeleton frame, walking leg part, support frame, gripping part, propulsion part, or similar mechanical structure of the robot. That is, the driving target part is not limited to a joint that performs only rotational movement, but may include any mechanical target part that performs bending, extension, support, gripping, posture maintenance, or response to external force. The robot may be implemented as a collaborative robot, a service robot, an exoskeleton robot, a rehabilitation assistance robot, a walking robot, a medical robot, an underwater robot, or a small robot, and the robot driving device (600) may be configured to be mounted on a specific driving target part of these robots.

[0189] In the present disclosure, a robot drive unit (600) may be coupled to a driving target as a single independent unit. For example, one robot drive unit (600) may be arranged to correspond to one joint, or multiple robot drive units (600) may be arranged to correspond to each of multiple joints. Additionally, the robot drive unit (600) may be embedded inside the driving target, or it may be placed outside the driving target and then indirectly connected through a tendon-type connection, link, bracket, or outer shell structure. Accordingly, the present disclosure can encompass robot internal type, external attachment type, and distributed type robot drive structures.

[0190] According to one embodiment of the present disclosure, a robot drive unit (600) may include a string actuator module (200) that generates a contracting force by twisting a twist string according to the rotation of a drive source, and a fluid core (400) that accommodates at least a portion of the twist string within a fluid. Additionally, in another embodiment, the robot drive unit (600) may further include a variable stiffness structure (300). Such configurations may be selectively adopted depending on the level of motion requirements of the robot. For example, if a relatively simple linear drive or tensile drive is required, it may be configured around the string actuator module (200) and the fluid core (400), and if it is necessary to adjust the stiffness state of the structure as well, it may be implemented as an integrated configuration with the addition of the variable stiffness structure (300). Accordingly, in an embodiment applied to a robot, both a basic drive unit including the fluid core (400) and an extended drive unit including the variable stiffness structure (300) may be adopted.

[0191] The arrangement relationship between the driving target and the robot driving device (600) can take various forms. For example, in a robot finger-type driving target, the robot driving device (600) may be positioned at the base or side of the finger, a twist string may extend along the longitudinal direction of the finger, and, if necessary, a variable stiffness structure (300) may form the outer or inner skeleton of the finger. In an exoskeleton-type robot, the robot driving device (600) may be positioned on the outer frame of the user's joint, and the twist string and the variable stiffness structure (300) may be designed to be coupled with the direction of joint flexion. In a walking robot or a link-type robot, the robot driving device (600) may be positioned inside or on the side of the link to provide joint torque or support force. Accordingly, the present disclosure may include various arrangement relationships between the driving target and the robot driving device (600) regardless of the shape of the robot.

[0192] According to one embodiment of the present disclosure, the robot drive unit (600) can be applied to various robot applications where contractile drive, variable stiffness structure, and fluid environment control are simultaneously required. For example, in a collaborative robot, the robot drive unit (600) can be applied to a link or end effector portion where there is a high possibility of contact with the outside, and in a walking robot, it can be applied to a repetitive load transfer section such as a leg portion or an ankle portion. In addition, in an exoskeleton or rehabilitation aid, the robot drive unit (600) can be placed in a drive target portion that extends parallel to the user's body to perform flexion, extension, or support movements. In a small medical robot or micro drive unit, a local drive structure can be implemented using a relatively miniaturized string actuator module (200) and a fluid core (400). Accordingly, the robot drive unit (600) of the present disclosure is not limited to one specific robot category and can be applied to a wide range of robot fields where structural support and drive are simultaneously required.

[0193] Additionally, in embodiments applied to robots, a control unit, a restraint unit (310), a magnetic field generator (430), and a sensor may be optionally combined. For example, in a robot performing high-precision tasks, consensus control and effective radius model-based control for a plurality of string actuator modules (200) may be applied, and in a robot where response to external forces is important, linked control of the restraint state of the structure and magnetic field generation conditions may be used together. However, in embodiments applied to robots, not all additional components are always mandatory, and only some components may be selectively adopted depending on the structure of the driven target, required degrees of freedom, load conditions, and level of control requirements. Accordingly, the present disclosure can encompass various configuration ranges, such as basic type, extended type, and high-level control type, even in embodiments applied to robots.

[0195] Meanwhile, a computer-readable medium storing a data structure is disclosed according to an embodiment of the present disclosure.

[0196] A computer-readable medium storing a data structure according to one embodiment of the present disclosure is disclosed. The aforementioned data structure may be stored in memory as described in the present disclosure, executed by a processor, and transmitted and received by a network unit.

[0197] A data structure can refer to the organization, management, and storage of data that enables efficient access and modification of data. A data structure can refer to the organization of data for solving specific problems (e.g., data analysis, data retrieval, data storage, data modification). A data structure may also be defined by physical or logical relationships between data elements designed to support specific data processing functions. Logical relationships between data elements may include connections between user-defined data elements. Physical relationships between data elements may include actual relationships between data elements physically stored on a computer-readable storage medium (e.g., a permanent storage device). Specifically, a data structure may include sets of data, relationships between data, and functions or instructions applicable to the data. Through an effectively designed data structure, a computing device can perform operations while minimizing the use of the computing device's resources. Specifically, through an effectively designed data structure, a computing device can increase the efficiency of operations, reading, insertion, deletion, comparison, exchange, and retrieval.

[0198] Data structures can be classified into linear and non-linear data structures based on their form. A linear data structure is one where only one piece of data is connected to the next. Linear data structures can include lists, stacks, queues, and deques. A list can refer to a set of data that maintains an internal order. Lists can include linked lists. A linked list is a data structure where data is connected in a line, with each piece of data possessing a pointer. In a linked list, the pointer can contain information regarding the connection to the next or previous data. Depending on its form, a linked list can be represented as a singly linked list, a doubly linked list, or a circular linked list. A stack is a data arrangement structure that allows for restricted access to data. A stack can be a linear data structure where data can be processed (e.g., insertion or deletion) only at one end. Data stored in a stack can be a Last-In, First-Out (LIFO) data structure, meaning that the later an item is entered, the sooner it is retrieved. A queue is a data sequence structure that allows for limited access to data; unlike a stack, it can be a FIFO (First in First Out) data structure where data stored later is retrieved later. A deque is a data structure that can process data at both ends.

[0199] Non-linear data structures can be structures where multiple data are connected after a single piece of data. Non-linear data structures may include graph data structures. A graph data structure can be defined by vertices and edges, and an edge may include a line connecting two different vertices. Graph data structures may include tree data structures. A tree data structure may be a data structure where there is only one path connecting two different vertices among the multiple vertices included in the tree. In other words, it may be a data structure that does not form a loop in a graph data structure.

[0200] Throughout this specification, the terms artificial intelligence-based model, computational model, neural network, network function, and neural network may be used interchangeably. Hereinafter, they will be described uniformly as neural network. A data structure may include a neural network. Furthermore, a data structure including a neural network may be stored on a computer-readable medium. A data structure including a neural network may also include data preprocessed for processing by the neural network, data input to the neural network, weights of the neural network, hyperparameters of the neural network, data obtained from the neural network, activation functions associated with each node or layer of the neural network, loss functions for learning the neural network, etc. A data structure including a neural network may include any of the components disclosed above. That is, a data structure including a neural network may be configured to include all or any combination thereof, such as data preprocessed for processing by the neural network, data input to the neural network, weights of the neural network, hyperparameters of the neural network, data obtained from the neural network, activation functions associated with each node or layer of the neural network, and loss functions for learning the neural network. In addition to the configurations described above, a data structure including a neural network may include any other information that determines the characteristics of the neural network. Furthermore, the data structure may include any form of data used or generated during the computational process of the neural network, and is not limited to the foregoing. A computer-readable medium may include a computer-readable recording medium and / or a computer-readable transmission medium. A neural network may be composed of a set of interconnected computational units that may generally be referred to as nodes. These nodes may also be referred to as neurons. A neural network is composed of at least one node.

[0201] A data structure may include data input to a neural network. A data structure including data input to a neural network may be stored on a computer-readable medium. Data input to a neural network may include training data input during the neural network learning process and / or input data input to a neural network after training is complete. Data input to a neural network may include pre-processed data and / or data subject to pre-processing. Pre-processing may include a data processing process for inputting data into a neural network. Accordingly, a data structure may include data subject to pre-processing and data generated by pre-processing. The aforementioned data structure is merely an example, and the present disclosure is not limited thereto.

[0202] The data structure may include weights of the neural network. (In this specification, weights and parameters may be used interchangeably.) The data structure including the weights of the neural network may be stored on a computer-readable medium. The neural network may include multiple weights. The weights may be variable and may be varied by a user or an algorithm to enable the neural network to perform a desired function. For example, if one or more input nodes are interconnected to a single output node by respective links, the output node may determine the data value output from the output node based on values ​​input to the input nodes connected to the output node and weights set on the links corresponding to each input node. The aforementioned data structure is merely an example and the present disclosure is not limited thereto.

[0203] As an example rather than a limitation, weights may include weights that vary during the neural network learning process and / or weights for which neural network learning is completed. Weights that vary during the neural network learning process may include weights at the start of the learning cycle and / or weights that vary during the learning cycle. Weights for which neural network learning is completed may include weights for which the learning cycle is completed. Accordingly, a data structure containing the weights of a neural network may include a data structure containing weights that vary during the neural network learning process and / or weights for which neural network learning is completed. Therefore, the weights and / or combinations of each weight described above are included in the data structure containing the weights of a neural network. The aforementioned data structure is merely an example and the present disclosure is not limited thereto.

[0204] Data structures containing the weights of a neural network may be stored on a computer-readable storage medium (e.g., memory, hard disk) after undergoing a serialization process. Serialization may be a process of converting a data structure into a form that can be stored on the same or different computing devices and later reconstructed for use. A computing device may serialize the data structure to transmit and receive data over a network. A serialized data structure containing the weights of a neural network may be reconstructed on the same or different computing devices through deserialization. Data structures containing the weights of a neural network are not limited to serialization. Furthermore, data structures containing the weights of a neural network may include data structures designed to increase computational efficiency while minimizing the use of computing device resources (e.g., B-Tree, R-Tree, Trie, m-way search tree, AVL tree, Red-Black Tree in non-linear data structures). The foregoing is merely an example and the present disclosure is not limited thereto.

[0205] The data structure may include hyperparameters of the neural network. The data structure including the neural network hyperparameters may be stored on a computer-readable medium. The hyperparameters may be variables that are varied by the user. The hyperparameters may include, for example, a learning rate, a cost function, the number of learning cycle iterations, weight initialization (e.g., setting the range of weight values ​​subject to weight initialization), and the number of hidden units (e.g., the number of hidden layers, the number of nodes in the hidden layers). The aforementioned data structure is merely an example, and the present disclosure is not limited thereto.

[0207] FIG. 7 is a brief and general schematic diagram of an exemplary computing environment in which embodiments of the present disclosure may be implemented.

[0208] Although the present disclosure has been described as generally being implementable by a computing device, a person skilled in the art will be well aware that the present disclosure may be implemented in combination with computer-executable instructions and / or other program modules that can be executed on one or more computers and / or as a combination of hardware and software.

[0209] Generally, a program module includes routines, programs, components, data structures, etc., that perform a specific task or implement a specific abstract data type. Furthermore, a person skilled in the art will be well aware that the method of the present disclosure can be implemented in other computer system configurations, including single-processor or multi-processor computer systems, minicomputers, mainframe computers, as well as personal computers, handheld computing devices, microprocessor-based or programmable consumer electronics, etc. (each of which may be connected to and operated with one or more associated devices).

[0210] The embodiments described in this disclosure may also be implemented in a distributed computing environment in which tasks are performed by remote processing devices connected via a communication network. In a distributed computing environment, program modules may be located in both local and remote memory storage devices.

[0211] Computers typically include various computer-readable media. Any medium accessible by a computer may be a computer-readable medium, and such computer-readable media include volatile and non-volatile media, transitory and non-transitory media, and removable and non-removable media. By example, but not limiting, computer-readable media may include computer-readable storage media and computer-readable transmission media. Computer-readable storage media include volatile and non-volatile media, transitory and non-transitory media, and removable and non-removable media implemented by any method or technique for storing information such as computer-readable instructions, data structures, program modules, or other data. Computer-readable storage media include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technologies, CD-ROM, DVD (digital video disk) or other optical disk storage devices, magnetic cassettes, magnetic tapes, magnetic disk storage devices or other magnetic storage devices, or any other media that can be accessed by a computer and used to store desired information.

[0212] Computer-readable transmission media typically include all information transmission media that implement computer-readable instructions, data structures, program modules, or other data, etc., on a modulated data signal, such as a carrier wave or other transport mechanism. The term modulated data signal means a signal in which one or more of the characteristics of the signal are set or modified to encode information within the signal. By example, not limiting, computer-readable transmission media include wired media, such as wired networks or direct-wired connections, and wireless media, such as acoustic, RF, infrared, and other wireless media. Any combination of the media described above is also considered to be within the scope of computer-readable transmission media.

[0213] An exemplary environment for implementing various aspects of the present disclosure, including a computer (1102), is shown, wherein the computer (1102) includes a processing unit (1104), system memory (1106), and a system bus (1108). The system bus (1108) connects system components, including system memory (1106) (but not limited thereto), to the processing unit (1104). The processing unit (1104) may be any processor among various commercial processors. Dual processors and other multiprocessor architectures may also be used as the processing unit (1104).

[0214] The system bus (1108) may be any of several types of bus structures that can be additionally interconnected to a local bus using any of the memory bus, peripheral bus, and various commercial bus architectures. System memory (1106) includes read-only memory (ROM) (1110) and random access memory (RAM) (1112). The basic input / output system (BIOS) is stored in non-volatile memory (1110), such as ROM, EPROM, EEPROM, etc., and this BIOS includes basic routines that help transfer information between components within the computer (1102) at times such as during startup. The RAM (1112) may also include high-speed RAM, such as static RAM, for caching data.

[0215] The computer (1102) also includes an internal hard disk drive (HDD) (1114) (e.g., EIDE, SATA)—this internal hard disk drive (1114) may also be configured for external use within a suitable chassis (not shown)—a magnetic floppy disk drive (FDD) (1116) (e.g., for reading from or writing to a removable diskette (1118)), and an optical disk drive (1120) (e.g., for reading from a CD-ROM disk (1122) or reading from or writing to other high-capacity optical media such as a DVD). The hard disk drive (1114), the magnetic disk drive (1116), and the optical disk drive (1120) may each be connected to the system bus (1108) by a hard disk drive interface (1124), a magnetic disk drive interface (1126), and an optical drive interface (1128). The interface (1124) for implementing an external drive includes at least one or both of USB (Universal Serial Bus) and IEEE 1394 interface technologies.

[0216] These drives and associated computer-readable media provide non-volatile storage of data, data structures, computer-executable instructions, etc. In the case of a computer (1102), the drives and media correspond to storing any data in a suitable digital format. Although the description of computer-readable media above refers to HDDs, removable magnetic disks, and removable optical media such as CDs or DVDs, a person skilled in the art will know that other types of computer-readable media, such as zip drives, magnetic cassettes, flash memory cards, cartridges, etc., may also be used in exemplary operating environments and that any of these media may contain computer-executable instructions for performing the methods of the present disclosure.

[0217] A number of program modules, including an operating system (1130), one or more application programs (1132), other program modules (1134), and program data (1136), may be stored in the drive and RAM (1112). All or part of the operating system, application, module and / or data may also be cached in RAM (1112). It will be well known that the present disclosure may be implemented in various commercially available operating systems or combinations of operating systems.

[0218] The user can input commands and information into the computer (1102) through one or more wired / wireless input devices, such as a pointing device like a keyboard (1138) and a mouse (1140). Other input devices (not shown) may include a microphone, an IR remote control, a joystick, a game pad, a stylus pen, a touch screen, etc. These and other input devices are often connected to the processing unit (1104) via an input device interface (1142) connected to the system bus (1108), but may also be connected via other interfaces such as a parallel port, an IEEE 1394 serial port, a game port, a USB port, an IR interface, etc.

[0219] A monitor (1144) or other type of display device is also connected to the system bus (1108) via an interface such as a video adapter (1146). In addition to the monitor (1144), the computer generally includes other peripheral output devices (not shown), such as speakers, a printer, and so on.

[0220] The computer (1102) may operate in a networked environment using a logical connection to one or more remote computers, such as remote computer(s) (1148), via wired and / or wireless communication. The remote computer(s) (1148) may be a workstation, a computing device computer, a router, a personal computer, a portable computer, a microprocessor-based entertainment device, a peer device, or other conventional network node, and generally include many or all of the components described for the computer (1102), but for brevity, only the memory storage device (1150) is illustrated. The illustrated logical connection includes a wired / wireless connection to a local area network (LAN) (1152) and / or a larger network, e.g., a wide area network (WAN) (1154). Such LAN and WAN networking environments are common in offices and companies and facilitate enterprise-wide computer networks, such as intranets, all of which can be connected to a global computer network, e.g., the Internet.

[0221] When used in a LAN networking environment, the computer (1102) is connected to a local network (1152) via a wired and / or wireless communication network interface or adapter (1156). The adapter (1156) may facilitate wired or wireless communication to the LAN (1152), and the LAN (1152) may also include a wireless access point installed therein to communicate with the wireless adapter (1156). When used in a WAN networking environment, the computer (1102) may include a modem (1158), be connected to a communication computing device on the WAN (1154), or have other means to establish communication through the WAN (1154), such as through the Internet. The modem (1158), which may be an internal or external and a wired or wireless device, is connected to the system bus (1108) via a serial port interface (1142). In a networked environment, the program modules described for the computer (1102) or parts thereof may be stored in a remote memory / storage device (1150). It will be well known that the illustrated network connection is exemplary and that other means of establishing a communication link between computers may be used.

[0222] The computer (1102) operates to communicate with any wireless device or object that is deployed and operated via wireless communication, for example, a printer, scanner, desktop and / or portable computer, PDA (portable data assistant), communication satellite, any equipment or place associated with a wireless detectable tag, and a telephone. This includes at least Wi-Fi and Bluetooth wireless technologies. Accordingly, the communication may be a predefined structure as in a conventional network, or simply ad hoc communication between at least two devices.

[0223] Wi-Fi (Wireless Fidelity) enables connectivity to the Internet and other sources without wires. Wi-Fi is a wireless technology, similar to a cell phone, that allows devices, such as computers, to transmit and receive data indoors and outdoors—that is, anywhere within the coverage area of ​​a base station. Wi-Fi networks use a wireless technology called IEEE 802.11 (a, b, g, etc.) to provide secure, reliable, and high-speed wireless connections. Wi-Fi can be used to connect computers to each other, to the Internet, and to wired networks (using IEEE 802.3 or Ethernet). Wi-Fi networks can operate in unlicensed 2.4 and 5 GHz wireless bands, for example, at data rates of 11 Mbps (802.11a) or 54 Mbps (802.11b), or in products that include both bands (dual band).

[0224] Those skilled in the art of the present disclosure will understand that information and signals may be represented using any various different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced in the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0225] Those skilled in the art will understand that the various exemplary logical blocks, configurations, modules, logics, processors, means, circuits, and algorithm steps described in connection with the embodiments disclosed herein may be implemented by electronic hardware, various forms of computer programs or design code (referred to herein as software for convenience), or a combination of all such. To clearly illustrate this interoperability between hardware and software, the various exemplary logical blocks, configurations, modules, logics, processors, means, circuits, and steps have been generally described above in relation to their functions. Whether such functions are implemented in hardware or software depends on the design constraints imposed on the specific application and the overall system. Those skilled in the art may implement the functions described in this disclosure in various ways for each specific application, but such implementation decisions should not be interpreted as being outside the scope of this disclosure.

[0226] The various embodiments presented herein may be implemented as methods, devices, or articles manufactured using standard programming and / or engineering techniques. The term "article manufactured" includes a computer program, a carrier, or a medium accessible from any computer-readable storage device. For example, computer-readable storage media include, but are not limited to, magnetic storage devices (e.g., hard disks, floppy disks, magnetic strips, etc.), optical discs (e.g., CDs, DVDs, etc.), smart cards, and flash memory devices (e.g., EEPROMs, cards, sticks, key drives, etc.). Additionally, the various storage media presented herein include one or more devices and / or other machine-readable media for storing information.

[0227] It should be understood that the specific order or hierarchy of steps in the presented processes is an example of exemplary approaches. It should be understood that the specific order or hierarchy of steps in the processes may be rearranged within the scope of this disclosure based on design priorities. The appended method claims provide elements of various steps in a sample order, but do not imply being limited to the specific order or hierarchy presented.

[0228] Description of the presented embodiments is provided so that a person skilled in the art may use or practice the present disclosure. Various modifications to these embodiments will be apparent to a person skilled in the art, and the general principles defined herein may be applied to other embodiments without departing from the scope of the present disclosure. Thus, the present disclosure is not limited to the embodiments presented herein, but should be interpreted in the broadest possible scope consistent with the principles and novel features presented herein.

Claims

Claim 1 A robot drive device comprising: a string actuator module in which a twisting string is twisted to generate a contracting force according to the rotation of a driving source; a variable stiffness structure driven by the contracting force of the string actuator module; and a fluid core comprising a housing that accommodates at least a portion of the twisting string and a fluid accommodated in the housing. Claim 2 A robot drive device according to claim 1, wherein the driving source includes a motor, and the rotation axis of the motor is directly coupled to a rotating member that twists the twist string. Claim 3 A robot driving device according to claim 1, wherein the twist string comprises at least one of a wire, fiber, or filament formed integrally by arranging a plurality of strands in parallel. Claim 4 A robot driving device according to claim 1, wherein the twist section of the twist string is disposed inside the housing, and the end of the twist string is coupled to the variable stiffness structure outside the housing. Claim 5 A robot driving device according to claim 1, wherein the fluid comprises a magnetic fluid, and the robot driving device further comprises a magnetic field generating unit that applies a magnetic field to the magnetic fluid inside the housing. Claim 6 A robot driving device according to claim 5, wherein the magnetic field generating unit comprises a coil disposed on the inner or outer side of the housing. Claim 7 A robot driving device according to claim 5, wherein the twisted string is formed of a conductive material or includes a conductive coating layer, and the magnetic field generating unit includes a power supply unit that applies current to the twisted string. Claim 8 A robot drive device according to claim 4, wherein the housing comprises: a first flow space surrounding the twisted section; a storage space for receiving the fluid; and a first flow path connecting the storage space and the first flow space. Claim 9 A robot driving device according to claim 8, wherein the housing further comprises: a second flow space formed on the housing wall side spaced apart from the first flow space; and a second flow path connecting the first flow space and the second flow space. Claim 10 A robot drive device according to claim 9, wherein a heat exchange jacket is coupled to the outer side of the housing to be in thermal contact with the second flow space. Claim 11 A robot driving device according to claim 1, wherein the variable stiffness structure comprises a plurality of plate-shaped members or sheet-shaped members stacked to extend along the contraction direction of the twist string. Claim 12 A robot driving device according to claim 11, wherein the variable stiffness structure further comprises a restraining member that changes the relative movement state between adjacent plate-type members or sheet-type members. Claim 13 A robot driving device according to claim 12, wherein the restraining member comprises: a hermetic outer shell surrounding the plurality of plate-shaped members or sheet-shaped members; and a pressure reducing source for reducing pressure inside the hermetic outer shell. Claim 14 A robot driving device according to claim 12, wherein the restraining member comprises: an electrode layer disposed between the adjacent plate-shaped members or sheet-shaped members; and a power supply member that applies voltage to the electrode layer. Claim 15 A robot driving device according to claim 12, wherein the restraining member comprises a tension transmission member that compresses the plurality of plate-shaped members or sheet-shaped members in a stacking direction according to the contraction force of the string actuator module. Claim 16 A robot drive device according to claim 12, wherein the variable stiffness structure is configured to switch between a first state in which relative sliding between adjacent plate-shaped members or sheet-shaped members is allowed and a second state in which relative sliding between adjacent plate-shaped members or sheet-shaped members is restricted. Claim 17 In claim 16, the variable stiffness structure further has an intermediate constraint state between the first state and the second state, a robot driving device. Claim 18 A robot drive device according to claim 1, wherein a plurality of the string actuator modules are coupled to a single variable stiffness structure. Claim 19 In claim 18, the robot driving device further comprises a control unit, wherein the control unit drives the plurality of string actuator modules individually and is configured to select the number of string actuator modules to be driven among the plurality of string actuator modules. Claim 20 A robot driving device according to claim 19, wherein the control unit is configured to control the operation of the plurality of string actuator modules by agreement using at least one of the position, velocity, current, or tension of the plurality of string actuator modules. Claim 21 A robot driving device according to claim 19, wherein the control unit is configured to calculate the contraction amount or output force of the string actuator module using a model including an effective radius that changes according to the twist state of the twist string. Claim 22 In claim 19, the robot driving device further comprises at least one of a tension sensor, a current sensor, a voltage sensor, a back EMF sensor, a temperature sensor, a structural deformation sensor, or an external force sensor, and the control unit is configured to control the plurality of string actuator modules based on the detection value of the at least one sensor. Claim 23 In claim 19, the robot driving device further comprises a restraining member provided in the variable stiffness structure and a magnetic field generating member corresponding to the fluid core, and the control member is configured to change the driving conditions of the magnetic field generating member in conjunction with the driving state of the restraining member. Claim 24 A robot comprising: a driving target part that forms the skeleton or outer shape of the robot and performs a specific operation; and a robot driving device that provides driving force or supporting force to the driving target part, wherein the robot driving device comprises: a string actuator module in which a twisted string is twisted to generate a contracting force according to the rotation of a driving source; and a fluid core that accommodates at least a portion of the twisted string in a fluid.

Images