The present invention relates to a variable rigidity robot joint system including a first driving module and a second driving module generating torque which is rotated on a first direction, a first rotating module changing rotations of the first driving module and the second driving module into rotations on a second direction intersecting the first direction when the first and second driving modules rotate in directions in which a joint is rotated in a same direction, thereby rotating the joint, a rigidity-providing member providing rigidity by elastically supporting a rotational movement of the first rotating module on the second direction, and a second rotating module changing rotations of the first driving module and the second driving module into a linear motion in the first direction when the first and second driving modules rotate in directions in which the joint is rotated in different directions.

Variable stiffness devices and methods of their use are provided. In some embodiments, a variable stiffness device comprises an inner member defining a compartment for receiving an actuating fluid; an outer member disposed around the inner member; and a granular medium disposed between the inner member and the outer member; wherein the inner member is being moveable in a radial direction from a relaxed state to an expanded state by introducing the actuating fluid into the compartment of the inner member to compress the granular medium against the outer member to increase the stiffness of the device.

An actuator includes an output link; an input member, wherein the output link and the input member are rotatable about an axis of rotation; an elastic member disposed between the output link and the input member and configured to allow transmission of torque between the output link and the input member about the axis of rotation, and to allow at the same time, as a result of elastic deformation of the elastic member, a relative rotation between the output link and input member about the axis of rotation; and a thermo-active module comprising one or more thermoplastic inserts, wherein the thermoplastic inserts are configured to apply a variable resistance between the output link and the input member and provide an adjustable damping between the output link and the input member.

A supernumerary robotic limb (SRL) system can include a plurality of rigid links, a joint that connects one rigid link to another rigid link in the plurality of rigid arms, and two variable stiffness actuators (VSAs) configured to drive the plurality of rigid links in order to complete at least one task. The VSAs can exhibit infinite rotation and infinite stiffness. The VSAs can include an output link. Additionally, the VSAs can include a set of elastic elements mounted on the output link. The VSAs can include an input link configured to provide kinetic energy for the output link. The VSAs can include a dynamic chassis configured to connect with the input link. Additionally, the VSAs can include a stiffness adjustor included in the dynamic chassis and configured to adjust an elastic transmission between at least one elastic element of the set of elastic elements and the output link.

The subject matter of the invention is an articulation (1) with controllable stiffness and a force-measuring system, comprising a first device (20) that comprises a frame (4) having a curved face and connected to a first motor element (2), the first device (20) regulating the position of the articulation (1), and a second device (22) that regulates the stiffness of the articulation (1) and comprises a thrust element (15), the movement (D) of which determines the pre-compression of a resistive element (11) and thus the stiffness of the articulation (1); the first motor element (2) causes the frame (4) to rotate such that a wheel (8) of the second device (22) rolls on the curved face of the frame (4), causing the resistive element (11) to be compressed (C) via a transmission rod (7) associated with the wheel (8) and with the resistive element (11).

An actuator includes an effective stiffness. The effective stiffness is based at least in part on non-linear deflection characteristics of buckling. A method of varying an effective stiffness of an actuator includes providing an actuator and varying an effective stiffness of the actuator based at least in part on non-linear deflection characteristics of buckling. Another method of varying an effective stiffness of an actuator includes applying a load to a member. The load causes the member to buckle, and the buckling produces non-linear deflection of the member. The method further includes varying an effective stiffness of an actuator based at least in part on the non-linear deflection of the member.

Disclosed is a reconfigurable rotary series elastic element (RSEE) comprising: an inner tension spring mount: an outer tension spring mount; and a plurality of tension springs connected between the inner tension spring mount and outer 5 tension spring mount. A position at which each spring connects to one or both of the inner tension spring mount and outer tension spring mount: can be changed to adjust a relationship between an output torque and deflection angle of the RSEE; and is configured such that, during relative rotation of the inner tension spring mount and outer tension spring mount, an amount of tension in 10 at least one said tension spring differs from an amount of tension in at least one other said tension spring.

A stiffness control apparatus includes a base member, an output link configured to move along a plane parallel to a surface of the base member, and at least one stiffness control unit configured to control stiffness of the output link. The at least one stiffness control unit includes a shaft including a first end and a second end, the first end being rotatably coupled to the base member, a rotating member including an elongated hole into which the second end of the shaft is movably inserted, and rotatably arranged by the shaft at a position having contact with the output link on an outer side or an inner side the output link, and an elastic member between the second end of the shaft and at least one inner wall of the elongated hole in a longitudinal direction thereof.

A tensioning set comprises an output member. A magnetorheological fluid clutch apparatus is configured to receive a degree of actuation (DOA) and connected to the output member, the magnetorheological fluid clutch apparatus being actuatable to selectively transmit the received DOA through the output member by controlled slippage. A tensioning member is connected to the output member so as to be pulled by the output member upon actuation of the magnetorheological fluid clutch apparatus, a free end of the tensioning member adapted to exert a pulling action transmitted to an output when being pulled by the output member. The tensioning set, or a comparable compressing set, may be used in systems and robotic arms. A method for controlling movements of an output driven by the tensioning set or compressing set is also provided.

An elastic actuator is provided, which may include a position motor and an electromagnetic spring. The position motor may include a motor output shaft. The electromagnetic spring may include a rotor, a stator and a gear set. The stator may drive the rotor to rotate. The gear set may include a first output shaft, a second output shaft and an output shaft; the first input shaft may connect the motor output shaft, and the second input may connect to the rotor. The power generated by the rotor and the power generated by the position motor may be outputted from the output shaft after being coupled via the gear set.