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Structure from the geometry and analysis of the three-spherical kinematic chain-base parallel mechanism have been studied. The parallel mechanism evolved from an origami fold as chain legs with three spherical kinematic chains becoming rigid bodies. The parallel mechanism with a three 6R kinematic chain as three chain legs is complicated. The reconfiguration of the parallel mechanism with full tilt–circle movement, kinematic, and workspace are investigated, too. This parallel mechanism can be applied in specific applications with certain treatments. [ABSTRACT FROM AUTHOR]

Origami-inspired mechanisms are extensively utilized in aerospace, medical devices, and soft robotics due to their simplicity, reliability, and high fold-to-deploy ratio. However, actuating these structures for deployment remains challenging. This paper presents a design method for self-deployable origami utilizing the rigid-elastic coupling spherical mechanism. Initially, the rigid-elastic coupling spherical mechanism is designed by replacing one revolute joint of the rigid spherical mechanism with a V-shaped elastic nickel–titanium (Ni–Ti) alloy wire. We show that the rigid-elastic coupling spherical mechanism has equivalent kinematics to the associated rigid spherical mechanism, which is also the equivalent mechanism of the rigid-elastic coupling origami unit. By leveraging the elastic deformation of the Ni–Ti alloy wire in conjunction with the motion of the revolute joints, the rigid-elastic coupling mechanism acquires bistable characteristics, thereby enabling shape memory for self-deployment. The typical origami patterns, such as Miura-ori and Yoshimura-ori, are employed as design examples to showcase the performances of the associated self-deployable origami. • We present a design method for self-deployable origami. • We design the rigid-elastic coupling mechanism and show its kinematic equivalence. • We analyze the bistable and configuration maintenance characteristics. • We employ Miura-ori and Yoshimura-ori patterns to showcase our design. [ABSTRACT FROM AUTHOR]

The article presents a method for calculating and designing spherical roller gears with a double-row pinion. The studied gears are analogs of planetary gears with a double-wheel pinion. They make it possible to implement a wide range of gear ratios. The advantages of spherical roller gears include small dimensions, low material consumption, and layout properties. A special feature of the proposed calculation algorithm is the search for optimal geometric gears parameters according to the criteria of maximum efficiency coefficient taking into account maximum load capacity for a given maximum radial dimensions. The main criterion of strength is fatigue endurance. The method includes design and verification calculations. It makes it possible to develop the small-sized speed reducers for low-speed drives for various purposes.

Structure from the geometry and analysis of the three-spherical kinematic chain-base parallel mechanism have been studied. The parallel mechanism evolved from an origami fold as chain legs with three spherical kinematic chains becoming rigid bodies. The parallel mechanism with a three 6R kinematic chain as three chain legs is complicated. The reconfiguration of the parallel mechanism with full tilt–circle movement, kinematic, and workspace are investigated, too. This parallel mechanism can be applied in specific applications with certain treatments.

The COVID-19 pandemic has placed unprecedented stress on the world healthcare system and demonstrated the need for modern automated robotic solutions for numerous medical applications. Often, robots that provide spherical motion of the end-effector are used in this area. In this paper, we discuss a spherical mechanism with a circular rail and provide several possible variations of the design: spherical robots with three or four legs and 4-DOF robots with an additional translational DOF, including a decoupled mechanism. The screw theory is used to analyze the mobility of the discussed mechanisms, and their advantages and drawbacks are discussed. [ABSTRACT FROM AUTHOR]

The COVID-19 pandemic has placed unprecedented stress on the world healthcare system and demonstrated the need for modern automated robotic solutions for numerous medical applications. Often, robots that provide spherical motion of the end-effector are used in this area. In this paper, we discuss a spherical mechanism with a circular rail and provide several possible variations of the design: spherical robots with three or four legs and 4-DOF robots with an additional translational DOF, including a decoupled mechanism. The screw theory is used to analyze the mobility of the discussed mechanisms, and their advantages and drawbacks are discussed.

According to the topological design theory of parallel mechanism(PM) based on position and orientation characteristic (POC) equations, a new three-rotational spherical PM with zero coupling degree is designed. Firstly, the POC, degree of freedom and coupling degree of the PM are calculated, it is found that the PM contains three BKC with zero coupling degree. Therefore, the analytical formula of the positive and inverse solution of the PM is directly derived; Then, the workspace of the PM is calculated and analyzed based on the position inverse solution formula and the singular configuration of the PM is analyzed based on the Jacobian matrix. This mechanism can be used as a joint for the shoulder, wrist and waist of a robot, or as an adjustment device of position and orientation. [ABSTRACT FROM AUTHOR]

As the instant centers in planar mechanisms, the instantaneous poles can be used for instantaneous kinematic analysis of spherical mechanisms. In this paper, a novel geometrical method is presented for isotropy analysis of spherical mechanisms via the concept of instantaneous poles. First, a different form of the Jacobian matrix is formulated for multi-degree-of-freedom (multi-DOF) spherical mechanisms, based on the instantaneous poles. Then, using the obtained Jacobian matrix, isotropy analysis of spherical mechanisms is carried out, and general conditions to have isotropic configurations are determined. The proposed method is fast and applicable for all types of spherical mechanisms. At last, two illustrative examples are presented to show the efficiency of the method.

A statically balanced mechanism is designed as a potential solution for the positioning of surgical instruments. Its kinematics with five degrees of freedom that decouples linear and angular motions is proposed for that objective. The linear motion of its end effector is provided by a classical parallelogram linkage. To enhance its adaptability, a mechanical system allows re-orienting the position mechanism in three different working modes (horizontal, upward and downward) while preserving its static balance. Based on the mechanical concept, a uniformized static balancing condition that considers all working modes is given. The orientation of the end effector is provided by a spherical decoupled mechanism. It generates a remote center of motion which is highly representative of kinematics in surgery requirements. Based on the mechanism kinematics, the evolution of its gravitational potential energy is studied. Two different mechanical concepts are then proposed to generate a compensating elastic potential energy. A CAD model of the entire mechanism has allowed the estimation of all mechanical parameters for the selection of the appropriate tension springs and for carrying out validation simulations. A prototype of the statically balanced mechanism is fabricated and successfully tested.

A variety of magnetic devices can be manipulated remotely using a single permanent “actuator” magnet positioned in space by a robotic manipulator. This paper describes the spherical-actuator-magnet manipulator (SAMM), which is designed to replace or augment the singularity-prone spherical wrist used by prior permanent-magnet manipulation systems. The SAMM uses three omniwheels to enable holonomic control of the heading of its magnet's dipole and to enable its magnet to be rotated continuously about any axis of rotation. The SAMM performs closed-loop control of its dipole's heading using field measurements obtained from Hall-effect sensors as feedback, combined with modeled dynamics, using an extended Kalman filter. We describe the operation and construction of the SAMM, develop and characterize controllers for the SAMM's spherical magnet, and demonstrate remote actuation of an untethered magnetic device in a lumen using the SAMM. [ABSTRACT FROM AUTHOR]

In this paper the dimensional synthesis of a spherical four link mechanism that can be used as a solar tracker is presented. With a spherical mechanism it is possible to have a tridimensional movement with one grade of freedom. The dimensional synthesis was based on finding the lengths of the components so that the paths required could be traced as close as possible. Different options were analyzed: crank, coupler, rocker and rocker pivot. It was possible to obtain an adjustable coupler for two trajectories within a small error to the application. [ABSTRACT FROM AUTHOR]

This work presents a method based on spherical trigonometry for computing all joint angles of the spherical metamorphic palm. The spherical palm is segmented into spherical triangles which are then solved and combined to fully solve the palm configuration. Further, singularity analysis is investigated with the analysis of each spherical triangle the palm is decomposed. Singularity-avoidance-based design criteria are then presented. Finally, point clouds are generated that represent the joint space of the palm as well as the workspace of the hand with the advantage of an articulated palm is shown. [ABSTRACT FROM AUTHOR]

It has been a challenge to design humanoid robots that possess intrinsic compliant actuation, especially for robots that are required to be manipulated multidimensionally. Adapting from human limbs, robotic manipulators with internal mechanical compliance can perform high-quality force/torque control and more safely interact with humans. This paper presents a humanoid robotic wrist whose size, range-of-motion, and torque density are comparable to those of a human wrist. To achieve 2-D series elastic actuation, two internal compliant couplers are proposed. Through slider crank and spherical mechanisms, the linear elasticity is converted to rotary elasticity to control the pitch and yaw torques at the same time. This new compact design realizes series elastic actuation in two perpendicular axes without increasing size or complexity relative to that without series elastic actuation. Experiments using a prototype demonstrate that the wrist can achieve accurate and fast force/torque control. We expect this novel compliant wrist to serve as an alternative for applications involving human–robot interaction. [ABSTRACT FROM PUBLISHER]

This paper presents a new end-effector as a key component for a robotic needle insertion-type intervention system and its kinematic analysis. The mechanism is designed as a spherical mechanism with a revolute joint and a curved sliding joint, and its links always move on the surface of a sphere. The remote centre of motion (RCM) of the designed mechanism is placed below the base of the mechanism to avoid contact with the patient's body, unlike the conventional end-effectors developed for needle insertion. For the proposed mechanism, the forward kinematics are solved in terms of input joint parameters and then the reverse kinematics are solved by using the cross-product relationship between each joint vector and a vector mutually perpendicular to the vectors. The kinematic solutions are confirmed by numerical examples. [ABSTRACT FROM AUTHOR]

A non-overconstrained three-DOF parallel orientation mechanism that is kinematically equivalent to the Agile Eye is presented in this paper. The output link (end-effector) of the mechanism is connected to the base by one spherical joint and by another three identical legs. Each leg comprises of, in turns from base, a revolute joint, a universal joint, and three prismatic joints. The three lower revolute joints are active joints, while all other joints are passive ones. Based on a special configuration, some three projective angles of the end-effector coordinates are fully decoupled with respect to the input actuated joints, that is, by actuating any revolute joint the end-effector rotates in such a way that the corresponding projective angle changes with the same angular displacement. The fully decoupled motion is analyzed geometrically and proved theoretically. Besides, the inverse and direct kinematics solutions of the mechanism are provided based on the geometric reasoning and theoretical proof. [ABSTRACT FROM PUBLISHER]

Abstract: The problem of path generation for the spherical 4R mechanism is solved using the Differential Evolution (DE) algorithm. Formulas for the spherical geodesics are employed in order to obtain the parametric equation for the generated trajectory. Direct optimization of the objective function gives the solution to the path generation task without prescribed timing. Therefore, there is no need to separate this task into two stages to perform the optimization. Moreover, the order defect problem can be solved without difficulty by means of manipulations of the individuals in the DE algorithm. Two examples of optimum synthesis showing the simplicity and effectiveness of this approach are included. [Copyright &y& Elsevier]

In this paper, a 4-DOF robotic arm for tool handling in laparoscopic surgery is introduced. The robot provides sufficient force to handle endoscopic tools used for large organ manipulation and is capable of measuring the tool-tissue forces. The RCM constraint is achieved using a spherical mechanism and roll and insertion motions are provided using time pulley and spindle-drive, respectively. The forward and inverse kinematics of the robot was solved and the dimensions of its links were determined, using particle swarm optimization method, so that the maximum kinematic and dynamic performance could be achieved. [ABSTRACT FROM AUTHOR]

Abstract: An atlas or catalogue of mechanisms provides a useful aid in the synthesis of mechanisms for new applications. The atlas stores mechanisms together with their coupler paths. Fourier techniques can be used as a convenient means for representing, in normalized form, curves for planar mechanisms. This paper looks at the extension to spherical four-bar mechanisms. In particular, a means for projecting a spherical curve onto a plane is discussed which depends only on the geometry of the curve and not on the choice of world coordinate system. [Copyright &y& Elsevier]

In-depth comprehension of human knee kinematics is necessary in prosthesis and orthosis design and in surgical planning but requires complex mathematical models. Models based on one-degree-of-freedom equivalent mechanisms have replicated well the passive relative motion between the femur and tibia, i.e. the knee joint motion in virtually unloaded conditions. In these mechanisms, fibres within the anterior and posterior cruciate and medial collateral ligaments were taken as isometric and anatomical articulating surfaces as rigid. A new one-degree-of-freedom mechanism is analysed in the present study, which includes isometric fibres within the two cruciates and a spherical pair at the pivot point of the nearly spherical motion as measured for this joint. Bounded optimization was applied to the mechanism to refine parameter first estimates from experimental measurements on four lower-limb specimens and to best-fit the experimental motion of these knees. Relevant results from computer simulations were compared with those from one previous equivalent mechanism, which proved to be very accurate in a former investigation. The spherical mechanism represented knee motion with good accuracy, despite its simple structure. With respect to the previous more complex mechanism, the less satisfactory results in terms of replication of natural motion were counterbalanced by a reduction of computational costs, by an improvement in numerical stability of the mathematical model, and by a reduction of the overall mechanical complexity of the mechanism. These advantages can make the new mechanism preferable to the previous ones in certain applications, such as the design of prostheses, orthoses, and exoskeletons, and musculoskeletal modelling of the lower limb. [ABSTRACT FROM AUTHOR]

Cam-roller mechanisms can be used in transmissions and robotic devices as an alternative to their bevel-gear counterparts. As bevel gears are used to couple shafts of intersecting axes, their cam-mechanism replacements are bound to have intersecting axes as well. This means that the contact surface of the cam must be conical, which leads to spherical cam mechanisms. Compared with gear transmissions, cam-roller mechanisms feature low friction, low backlash, and high strength. However, cam mechanisms may end up with a high pressure angle if negative action, a motion in which the cam is driven by mechanism rollers, occurs. This article reports the design of transmissions with spherical multilobe cams (MLCs), as a means to reduce the pressure angle. The kinematics of MLC, including profile generation, undercutting avoidance, and transmission-quality evaluation, is studied here. A case study has been included, in which the synthesis of a spherical MLC transmission is undertaken as a means to improve the transmission quality of a spherical epicyclic gear train. This train was introduced with the purpose of producing a singularity-free, unlimited-workspace pitch-roll wrist. [ABSTRACT FROM AUTHOR]

A compact, portable robot called CoBRASurge (Compact Bevel-geared Robot for Advanced Surgery) has been developed for tool guidance in minimally invasive surgery (MIS). It uses a spherical mechanism composed of bevel gears to achieve the necessary workspace in four degrees of freedom (DOF). Four DC motors drive the robot, with surgeon-in-the-loop control guided by an ergonomic joystick. The robot workspace has been validated experimentally, and motion trajectory experiments have shown robust and stable control. Use of the robot for camera guidance in porcine models is described. These experiments indicate superior functionality of the robot. Future work will involve integration of higher-function surgical tools with multiple CoBRASurge modules to create a complete, highly autonomous and portable MIS robot system for telesurgery. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, computer modelling and geometric construction of Burmester curve for synthesis of spherical mechanisms is presented. Rigid shell guidance in four specified positions on a sphere is performed by a 4R spherical linkage. The synthesis of such a linkage requires obtaining the associated Burmester curves on the reference sphere. Based on the Burmester theory and beside the computational and modelling abilities of the symbolic mathematical software namely Maple, an accurate as well as fast procedure for geometric construction of Burmester curve is developed. In the first part, the concepts of orientation and position on the sphere, pole of the motion and the related parameters are extended for modelling by the Maple. In the second part, the concepts of complementary axis quadrilateral and its imaginary motion, the center and circle axis cones and Burmester curve are derived. In the final part, using the prepared procedure and through a numerical example, a 4R spherical linkage for guiding an antenna to meet four specified postures in a three-dimensional working space is synthesized. [Copyright &y& Elsevier]

With the development of new technologies in surgery, minimally invasive surgery (MIS) has drastically improved the way conventional medical procedures are performed. However, a new learning curve has resulted requiring an expertise in integrating visual information with the kinematics and dynamics of the surgical tools. The Red DRAGON is a multi-modal simulator for teaching and training MIS procedures allowing one to use it with several modalities including: simulator (physical objects and virtual objects) and an animal model. The Red DRAGON system is based on a serial spherical mechanism in which all the rotation axes intersect at a single point (remote center) allowing the endoscopic tools to pivot around the MIS port. The system includes two mechanisms that incorporate two interchangeable MIS tools. Sensors are incorporated into the mechanism and the tools measure the positions and orientations of the surgical tools as well as forces and torques applied on the tools by the surgeon. The design is based on a mechanism optimization to maximize the manipulability of the mechanism in the MIS workspace. As part of a preliminary experimental protocol, five expert level surgeons performed three laparoscopic tasks – a subset of the Fundamental Laparoscopic Skill (FLS) set as a baseline for skill assessment protocols. The results provide an insight into the kinematics and dynamics of the endoscopic tools, as the underlying measures for objectively assessing MIS skills. [ABSTRACT FROM AUTHOR]

With a focus on design methodology for developing a compact and lightweight minimally invasive surgery (MIS) robot manipulator, the goal of this study is progress toward a next-generation surgical robot system that will help surgeons deliver healthcare more effectively. Based on an extensive database of in-vivo surgical measurements, the workspace requirements were clearly defined. The pivot point constraint in MIS makes the spherical manipulator a natural candidate. An experimental evaluation process helped to more clearly understand the application and limitations of the spherical mechanism as an MIS robot manipulator. The best configuration consists of two serial manipulators in order to avoid collision problems. A complete kinematic analysis and optimization incorporating the requirements for MIS was performed to find the optimal link lengths of the manipulator. The results show that for the serial spherical 2-link manipulator used to guide the surgical tool, the optimal link lengths (angles) are (60°, 50°). A prototype 6-DOF Surgical robot has been developed and will be the subject of further study. [ABSTRACT FROM AUTHOR]

• Geometrical model of a gripper designed from spherical mechanism. • Static analysis of grasped objects with various geometry. • Contact force measurement in grasp experiment. • Comparison of calculated and measured contact forces along the trajectory. • Grasp tests for objects with various geometry. This paper evaluates grasp capability of a new three-fingered gripper driven by optimal spherical four-link mechanism design. The optimal mechanism provided a trajectory that is approximately a grate circle arc. Therefore, independently driven three fingers of prototype either surround or compress an object with only one degree of freedom for each finger. Thus, the gripper provided both force-closure and form-closure grasp. The force variation of fingertip along the trajectory was presented comparative to calculations for 32 static cases of grasped cylindrical objects. Regression analysis between calculated values and measured data showed %99 reliability. The mechanism provided contact force between 155-215 N along the trajectory. The lifting load capability of the gripper without slip on ceramic surface with low friction was measured by using a commercial single side rubber band on the fingertips. 9 ± 0.05 kg lift capability for cylindrical objects without slip was observed. The prototype was tested for 11 grasp operations and 8 objects with various geometry. Each of the test showed success in the first grasp trial. [ABSTRACT FROM AUTHOR]

• Presents curvature measurement method for coupler orbit of spherical mechanism. • An optimization problem was formed and solved to design a spherical mechanism. • Calibration method was used for camera to track the coupler point of prototype. • XY coordinates of coupler point were recorded by the help of image processing. • The curvature of coupler point orbit for prototype and optimal design were compared. This research paper presents design of a gripper finger mechanism and a new curvature measurement method of fingertip trajectory. Firstly, the conditions of a grasp provided by gripper, which was designed from a spherical mechanism, was explained. Therefore, trajectory length of coupler point was modeled as objective function which is maximized. Ball-Burmester theory was used to form constraints which can provide a spherical curve with curvature close to zero. A plausible dimension range of mechanism, transmission angle, instantaneous invariants were arranged as constraint function. A meta-heuristic algorithm previously developed by one of authors was used to search the best instantaneous invariants based on the type of mechanism. The optimal solution was prototyped, and three-fingered gripper assembled. Secondly, an endoscopic camera peculiarly was used to measure curvature of the trajectory traced by coupler point of an optimal four-link spherical mechanism which was supposed to compose a finger of a robotic gripper. The coupler of the mechanism was expected to trace approximately a great circle arc to provide a grasp. Therefore, the technique to measure curvature was based on image processing and geodetic curvature theory. A calibrated endoscopic camera was used for acquisition of video record above the prototype which was centered in the center of the camera screen. The curvature of coupler point of optimal spherical mechanism design and prototype were compared. According to performed regression analysis, results of the measurement were %97 reliable for the useful part of the trajectory. [ABSTRACT FROM AUTHOR]

• Design of mechanism for Otologic Surgery. • Kinematic structure of the proposed mechanism. • Workspace and Joint space analysis of the proposed 2-DOF Spherical mechanism. • Influence of the design parameter on the workspace properties. • Workspace without non-singular assembly modes changing trajectories. During Otologic surgery, and more broadly during microsurgery, the surgeon encounters several difficulties due to the confined spaces and micro-manipulations. The purpose of the paper is to design a robot with a prescribed regular workspace shape to handle an endoscope to assist the Otologic surgery. A spherical parallel mechanism with two degrees of freedom is analysed in its design parameter space. This mechanism is composed of three legs (2USP-U) to connect the base to a moving platform connected to a double parallelogram to create a remote center of motion (RCM). Its kinematic properties, i.e. the singularity locus and the number of direct kinematic solutions, are investigated. For some design parameters, non-singular assembly modes changing trajectories may exist and have to be investigated inside the prescribed regular workspace shape. Two sets of design parameters are presented with their advantages and disadvantages. [ABSTRACT FROM AUTHOR]

A statically balanced mechanism is designed as a potential solution for the positioning of surgical instruments. Its kinematics with five degrees of freedom that decouples linear and angular motions is proposed for that objective. The linear motion of its end effector is provided by a classical parallelogram linkage. To enhance its adaptability, a mechanical system allows re-orienting the position mechanism in three different working modes (horizontal, upward and downward) while preserving its static balance. Based on the mechanical concept, a uniformized static balancing condition that considers all working modes is given. The orientation of the end effector is provided by a spherical decoupled mechanism. It generates a remote center of motion which is highly representative of kinematics in surgery requirements. Based on the mechanism kinematics, the evolution of its gravitational potential energy is studied. Two different mechanical concepts are then proposed to generate a compensating elastic potential energy. A CAD model of the entire mechanism has allowed the estimation of all mechanical parameters for the selection of the appropriate tension springs and for carrying out validation simulations. A prototype of the statically balanced mechanism is fabricated and successfully tested. [ABSTRACT FROM AUTHOR]

Surgical robots in popular clinical use are generally large machines, which limits their practical use to some extent. This study aims to investigate the potential of a small, table-mounted robot for tool guidance in minimally invasive surgery (MIS). In particular, its multipurpose use for guidance of various tools was investigated. A compact robot capable of manipulating MIS tools was designed and built. The robot can move in four degrees of freedom (DOF): three rotational and one translational. These DOF correspond to motion constrained by a trocar. The robot kinematics are based on a bevel-geared “spherical mechanism,” which allows trocar-constrained motion using a small mechanical device. The robot was tested in a porcine model by manipulating scopes and robotic grasping tools using a joystick as directed by a surgeon. Holding a laparoscope, the robot provided superior stability as a camera assistant. It manipulated the scope for visualization of the liver, spleen, bowel, etc. during manual tissue manipulation. Its compactness allowed increased space around the operating table, and the robot was in fact manipulated by joystick from across the room. Maneuvering grasping tools, the robot similarly provided a stable and dexterous platform for tissue manipulation. The test results suggest that the use of robotics for surgery may be enhanced via compact devices to include more hybrid robotic–manual procedures. The robot motion is smoother and more repeatable than that of a human operator. Use of a foot joystick could also place camera control directly with the surgeon. Flexible endoscopes can also be used with the robot for highly dexterous visualization. Notably, changing tools with this system is a very straightforward process and can be achieved without re-registration of the robot’s position/orientation. Therefore, combined with other simple robotic tools for grasping, cautery, etc., compact robotic systems based on this technology could replace the large systems in current use, potentially increasing the impact of robots on medical care. This represents an important step towards multifunctional compact surgical robots. [ABSTRACT FROM AUTHOR]

• Spherical mechanisms can be mapped to conical surfaces. • The Loop Sum Method finds the cone angle for spherical mechanisms. • The position analysis of conical developable mechanisms uses axis-angle rotations. • Projected angles connect conical and cylindrical developable mechanisms. • Examples of four-bar and multiloop spherical mechanisms are presented. An approach for designing developable mechanisms on a conical surface is presented. By aligning the joint axes of spherical mechanisms to the ruling lines, the links can be created in a way that the mechanism conforms to a conical surface. Terminology is defined for mechanisms mapped onto a right cone. Models are developed to describe the motion of the mechanism with respect to the apex of the cone, and connections are made to cylindrical developable mechanisms using projected angles. The Loop Sum Method is presented as an approach to determine the geometry of the cone to which a given spherical mechanism can be mapped. A method for position analysis is presented to determine the location of any point along the link of a mechanism with respect to the conical geometry. These methods are also applied to multiloop spherical mechanisms. [ABSTRACT FROM AUTHOR]