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The truss static structure system has excellent large load and lightweight characteristics. It is easy to embed actuators by substituting specific members in the structure and has the potential for multidimensional space deformation. Inspired by uniform tessellation structures, this article proposes a novel shape morphing mechanism (SMM) based on the combined design of tetrahedral-octahedral heterogeneous units (TOHUs). The relationship between the motion properties and driving configuration of the tetrahedral-octahedral units is analyzed to determine their conceptual configuration based on graph theory. Then, the weighted graph, adjacency matrix, and connection rules are evaluated to synthesize the conceptual structure for the truss mechanism. The results show that this configuration can allow multidimensional continuous deformations, including span, bend, sweep, and twist. A prototype is built to verify its deformability. Finally, the stiffness performance is analyzed based on the matrix displacement method. This research provides a comprehensive design method for constructing SMM, expands the range of combinable units and connection methods, and offers theoretical guidance for the innovative design of multidimensional deformation SMM in aerospace. [ABSTRACT FROM AUTHOR]

This work focuses on the synthesis of non-redundant planar kinematic chains applied to parallel manipulators, where the mobility of the kinematic chains is constrained by the planar workspace, allowing for kinematic chains with up to three degrees-of-freedom. The synthesis process consists of two stages. First, a graph generator enumerates non-isomorphic biconnected graphs representing planar kinematic chains with up to three degrees-of-freedom and seven loops. Subsequently, graphs associated to chains with rigid subchains are removed using a degeneracy identification method based on matroid theory. Concise results are presented for chains with up to five loops. For chains with six and seven loops, results are categorized based on link partitions for a direct comparison with previous results. These findings align with prior research, with minor variations in the reported chain numbers. These variations can be attributed to several factors, including graph generation, isomorphism testing, fractionation, and subchain identification. These factors are comprehensively discussed and examined. [ABSTRACT FROM AUTHOR]

Deployable polyhedral grippers have attracted increasing attention for their priority in noncontact capturing missions. Enrichment of these grippers may benefit the conduction of various capturing tasks. In this paper, novel deployable polyhedral grippers are presented. A design flow is proposed for the structural designs of diverse grippers. The core problem during the construction is reducible to the structural designs and combination of multiple synchronously deployable modules. Each module, containing three faces connected by two revolute joints, can realize one-degree-of-freedom deployment. Type synthesis of synchronously deployable modules adopting different layouts of revolute joints is conducted. The mobility and kinematics of these modules are analyzed to verify the achieved motion. As examples, four deployable polyhedral grippers based on different polyhedrons and deployment diagrams are presented. The deployment performance of the prototype proves the validity of the proposed design method and exhibits the potential of these deployable polyhedral grippers for diverse capturing missions. [ABSTRACT FROM AUTHOR]

Robotic devices are capable of reducing the physical burden on rehabilitation therapists and providing training programs of good repeatability, high efficiency, and high precision. When designing the kinematic structure for rehabilitation robots, there has been a growing interest toward one-degree-of-freedom (DOF) end-effector mechanisms due to their simpler structure and less complicated control algorithms. Compared with current one-DOF mechanism designs that are mainly customized for multi-joint robotic training, spherical coupled serial chain (SCSC) mechanisms are proposed in this paper to specifically deliver the single-joint robotic training, which is of equal importance to the effective physical recovery. Using kinematic mapping theory, the end-effector motion of SCSC mechanisms can be naturally transformed to two trigonometric curves composed of finite Fourier series in two separate planes of the image space. This novel formulation helps to establish an analytical and direct relationship between the design parameters of the SCSC mechanism and the harmonic parameters of the image-space representation of the task rehabilitation motion. The result is a simple and effective method for kinematic synthesis of SCSC mechanisms for generation of single-joint motion with an arbitrary number of spherical poses. An example of designing SCSC mechanisms for shoulder-joint rehabilitation is presented at the end of this paper to illustrate the feasibility of the proposed method. [ABSTRACT FROM AUTHOR]

A large-range-of-motion compliant transmission mechanism is introduced that uses the screw degrees-of-freedom (DOF) of a multi-DOF compliant module, sandwiched between two other single-DOF compliant modules, to convert a rotational input to a collinear translational output and vice versa. The geometric advantages (i.e., transmission ratios) of the mechanism when driven with a rotation to a translation or with a translation to a rotation can be tuned as desired. The freedom and constraint topologies (FACT) approach is used to design the mechanism, and stiffness matrices are used to explain why the transmission ratio of the mechanism is different depending on whether the mechanism is driven with its rotational or translational inputs. A version of the mechanism is fabricated and its transmission ratio is measured to be ~1.36 mm/deg when the mechanism is driven with a rotation, and is measured to be the inverse of ~1.89 mm/deg when the mechanism is driven with a translation. The transmission ratios both remain impressively constant over the mechanism's full range of motion and only vary slightly when they are actuated in different directions (i.e., counterclockwise or clockwise if the mechanism is driven with a rotation, or pushing or pulling if the mechanism is driven with a translation). [ABSTRACT FROM AUTHOR]

Power-split hybrid transmissions are the core components of power-split hybrid electric vehicles (HEVs), and the quest for a more energy-efficient and higher-performing power-split hybrid transmission has long been the focus of study. In contrast to previously published methodologies, this paper proposes a novel approach for directly synthesizing power-split hybrid transmissions that makes use of the results of previously synthesized planetary gear trains (PGTs) rather than necessitating a resynthesis of their PGTs. A new topological graph that can construct a bridge between the PGTs and power-split hybrid transmission has been developed, reducing the computational complexity in the synthesis process. The new topological graph is obtained by adding topological characteristics of the power-split hybrid transmission to the PGT graph. A standard structure matrix is proposed to further screen out all the isomorphic configurations. The present method can generate various types of multi-PGT hybrid transmissions while avoiding mechanical structural interference. The design process of configurations for power-split hybrid transmission with three-column PGTs (3-PGT) is used as an example to prove the rationality of the method. [ABSTRACT FROM AUTHOR]

Here, the morphology of a legged robot refers to the standing/crawling pose of the robot and the forward/backward orientation of the knee, which are related to the configurations of all leg mechanisms. The standing/crawling pose of the robot determines the body height and the leg supporting region size, which are related to the obstacle-traversing and arch-traversing capability. The proper knee orientation can reduce the leg-ground interference risk and help select a good foothold. Therefore, the terrain adaptability can be enhanced if the morphology of the legged robot is changeable. Motivated by this, a hexapod robot capable of morphology conversion is designed in this study. For the leg mechanism, a double-parallelogram transmission mechanism is used to change the forward/backward orientation of the knee. The hexapod robot can transform between the crawling pose and the standing pose and can also transform among four standing morphologies (i.e., the knee-elbow, knee-knee, elbow-knee, and elbow-elbow morphologies). The appropriate robot morphology can be determined according to the terrain type. The lateral reachable body workspaces are derived analytically for different morphologies, which is useful for motion planning. Simulations and experiments are used to verify the design and analysis of the hexapod robot. [ABSTRACT FROM AUTHOR]

As the most prestigious award in the field of machine design, the ASME Machine Design Award relishes its prestige and prominence. In the past 65 years since its inception in 1958, 60 eminent scholars have received this honor. This paper reviews the history of this prestigious award, including a summary of the contributions to the field of all 60 recipients, and acts as an archival document. Reviewing these awards in the past 65 years by following the tracks of its recipients elucidates developments in the field and significant contributions to the advancement of knowledge in machine design. In particular, novel contributions and remarkable achievements in the fields of mechanical engineering and machine design and development are recorded. This should be of interest to those interested in the study and in the historical development of mechanical engineering, particularly in machine design. [ABSTRACT FROM AUTHOR]

Reconfigurable mechanisms attract increasing attention for the characteristic to change structure configurations and motion behaviors in various multifunctional systems. By drawing inspiration from a kirigami fold, this paper presents a metamorphic double-loop linkage with multiple single-degree-of-freedom (DOF) reconfiguration branches, which is generated through combining two reconfigurable 6R plane-symmetric linkages. Mobility analysis of the metamorphic linkage is carried out in terms of the screw-loop theory equation, as well as the induced reconfiguration position identification. Then, this paper presents the specific reconfiguration conditions for the two single-loop components in this linkage, and a physical prototype fabricated by 3D printing verifies the ability of configuration reconstruction. Sixteen types of evolved motion branches are constructed by implementing different reconfiguration constraints, respectively, and corresponding kinematic paths are described by employing the specific angle between axes of joints. Furthermore, these evolved motion branches of this metamorphic linkage provide novel examples of mobile assemblies among several fundamental single-loop linkages. [ABSTRACT FROM AUTHOR]

Shape-morphing structures are beneficial for applications in aerospace, automotive, and architecture since they allow structures to adapt to changing environmental conditions. Finding structural configurations with intrinsic shape-morphing capabilities is, however, difficult due to the complexity of enabling and controlling target deformations while at the same time maintaining structural integrity. Existing solutions are often unstable, hard to fabricate, or limited to a single target state. Here, we show how lattice structures can be designed that morph from an initial state to one or multiple target states with a single kinematic degrees-of-freedom. Thus, the deformations of a structure can be fully controlled by controlling a single input node for every state. Since the structures are designed at the verge of kinematic determinacy, they become statically and kinematically determinate and hence load-carrying upon fixing the actuation node. As all deformations are described by inextensional mechanism modes, the kinematic and mechanical performance of the structures are decoupled and can be tuned individually. We further show that not only the target shape of a structure can be controlled, but also the kinematic path of a target node between its initial and its final position. The results are verified by fabricating the designs using multi-material 3D printing that enables direct fabrication of complex joints. Our work combines advantages of load-carrying lattice structures and distinct topological and geometric design to generate integrated kinematic solutions for a wide range of applications such as morphing wings, robotic grippers, and adaptive building facades. [ABSTRACT FROM AUTHOR]

Wave energy converter (WEC) mechanisms have been increasingly attracting the interest of institutions and companies, because of the energetic crisis and the energy demanded by small off-grid off-shore systems. Examples of WEC systems design date back to 1892 and, since then, different mechanisms have been proposed, based on different working principles. In this work, an attempt has been made to build an atlas of WEC devices, collecting them from the scientific and technical literature, as broadly as possible to the best of the authors' abilities. The working principle, the wave propagation direction, and the coast proximity have been used to classify the mechanisms of the atlas that have been illustrated by means of standardized esthetics. The topological nature of each device has been also extracted by applying both the polynomial representation of its kinematic chain (KC) together with a planar representation of the corresponding graph. These representations gave rise to a further and more detailed classification of the collected WEC devices that have been gathered together in peculiar topological families. Finally, system power has been also included to complete the information related to the devices illustrated in the atlas. [ABSTRACT FROM AUTHOR]

This paper presents a novel deployable antenna mechanism for synthetic aperture radar (SAR) satellites. First, the topological structure of the new deployable mechanism is designed based on the five conditions expected to be satisfied. Then, the kinematic model of the new mechanism is fully established based on vector equations and structural symmetry. Third, the deployed/folded ratio and interference of the new mechanism are analyzed. Finally, a typical numerical example is used to illustrate the effectiveness of the theoretical analysis, and a physical prototype is developed to show the fabrication feasibility of the new deployable mechanism. Compared with the latest counterpart for SAR satellites in the existing literature, the new deployable mechanism of this paper has a simpler driving system, simpler deployment movement, and no prismatic pairs with cold welding problems. With these characteristics, the presented new mechanism has a good application prospect in SAR satellites. [ABSTRACT FROM AUTHOR]

In order to solve the problem of non-unique solutions of actuating forces（or torques） and potentially antagonistic internal forces, the dynamic modeling and ensuing internal forces distribution and optimization of redundantly-actuated parallel mechanisms were studied. Firstly, taking the 3 RRR redundantly-actuated parallel robot as an example, the solution of displacement and velocity of the mechanism was determined based on the closed-loop vector method. Secondly, by resorting to the screw theory, a dynamic modeling approach was first proposed by means of the natural orthogonal complement, and then applied to obtain the inverse-dynamics equations of the 3 RRR mechanism, that overcomes the shortcomings of both the Newton-Euler and the Euler-Lagrange methods. Finally, the driving forces（or torques） were optimized by infinity-norm solution that minimizes the maximum-driving-torque, with simulation study of a circle trajectory tracking included as a verification. The research results show that, by applying the natural orthogonal complement and the minimization of the maximum-driving-torque, the proposed method decreases the power requirement of the redundant drivers from 1.5 Nm to 1.2 Nm, a significant reduction by 20%; it has the advantages of both simple and efficient derivation, with few intermediate variables, and has great application and reference value for modeling of redundantly-actuated mechanical systems and subsequent control law design. [ABSTRACT FROM AUTHOR]

The symmetrical origami waterbomb (WB) base shows promising applications in engineering due to its considerable mechanical behaviors. As a common phenomenon in actual origami, the stability performance of the WB base has attracted increasing attention. However, there are few studies on graphical design for the stability of WB bases. Based on the phase diagram of the intrinsic parameters, this paper proposes an intuitive and synthesized stability design method for the WB base. First, the basic principles are demonstrated using the Euler-Lagrange functional equation. In addition, the details of the method are illustrated by two typical WB bases with a given stiffness ratio. Second, according to the proposed design method, case studies are presented, and the stability behaviors are evaluated by the analytical method and finite element analysis (FEA) simulation. Finally, the prototypes of the case study are designed, and a measurement experiment of the stable states is carried out. Both FEA simulation and the experimental result demonstrate the effectiveness of the proposed design method. [ABSTRACT FROM AUTHOR]

To meet the increasing requirements for precision hybrid machine tools, this paper presents a geometric error propagation model-based accuracy synthesis method for parallel manipulators (PMs) with one translational and two rotational (1T2R) motion abilities. A unified geometric error propagation model of a family of 1T2R PMs is established with the first-order kinematic perturbation method. A set of geometric error propagation intensity indexes is formulated to describe the geometric error propagation characteristics in a quantitative manner. The equivalent effects of specified terminal accuracy are derived to directly determine the allowable values of all geometric source errors. Based on these, a computation algorithm is summarized for designating a tolerance allocation scheme to meet the specified terminal accuracy of a 1T2R PM. To demonstrate the accuracy synthesis method, a novel 1T2R PM with a 2UPR-1RPS ("R," revolute joint; "U," universal joint; "S," spherical joint; "P," prismatic actuated joint) topology is taken as an example to allocate geometric tolerances under the specified terminal accuracy. Following the tolerance allocation scheme, a laboratory prototype of the exemplary PM is fabricated and further experimentally measured. The measured kinematic results indicate that the prototype possesses an acceptable position error smaller than 0.15 mm, verifying the feasibility of the proposed accuracy synthesis method. Hence, the proposed method can be applied as a forward tolerance design tool to reduce the design iterations and development risks of low-mobility parallel robots. [ABSTRACT FROM AUTHOR]

In this paper, a novel four degrees-of-freedom (4DOF) articulated parallel forceps mechanism with a large orientation workspace (± 90 deg in pitch and yaw, 360 deg in roll rotations) is presented for robotic minimally invasive surgery. The proposed 3RSR-1UUP parallel mechanism utilizes a UUP center leg that can convert thrust motion of the 3RSR mechanism into gripping motion. This design eliminates the need for an additional gripper actuator, but also introduces the problem of unintentional gripper opening/closing due to parasitic motion of the 3RSR mechanism. Here, position kinematics of the proposed mechanism, including the workspace, is analyzed in detail, and a solution to the parasitic motion problem is provided. Human-in-the-loop simulations with a haptic interface are also performed to confirm the feasibility of the proposed design. [ABSTRACT FROM AUTHOR]

The paper presents an analytical approach for designing grooved cam mechanisms with a modified arrangement of the common translating follower. That is, an intermediate link having three rollers is added between the cam and the common follower. On the basis of an existing cam mechanism with a common roller follower, an intermediate link that has three rollers is added between the cam and the common follower. Such a cam mechanism has two sets of profile and can create multiple contact points between the cam and the follower at any instant. The two sets of profiles of such a cam mechanism can serve as the grooved types. Since the follower has three rollers that can simultaneously contact the cam at any instant, it can be positively driven along the guided groove of the cam contour. The contact forces and contact stresses of such a cam mechanism are analyzed to illustrate the advantage of spreading the force transmission and reducing the contact stress of this uncommon follower. The obtained results indicate that the contact stress at the surface of the cam and the follower for such a cam mechanism can be reduced by 30 to 47% in comparison with those of the cam mechanism with a common translating roller follower. In conclusion, the cam mechanism with a translating follower having an added ternary-roller intermediate link can be a preferable choice for the applications that follower is against heavy loads or moves at high speed. [ABSTRACT FROM AUTHOR]

This paper aims to present the topological structure design and kinematic analysis of a novel double-ring truss deployable satellite antenna mechanism. First, a new topological scheme and a new rectangular prism deployable linkage unit are proposed for constructing the kind of antenna mechanisms. Second, the degree-of-freedom (DOF) of the deployable unit and the antenna mechanism are analyzed based on structure decomposition and screw theory. Third, the kinematic model of the double-ring truss deployable antenna mechanism is established based on its structural characteristics. Finally, a typical numerical example is used to illustrate the effectiveness of the designed mechanism and the established kinematic model. The new double-ring truss deployable antenna mechanism consists of the units with the better structural symmetry and has simpler joint axis layouts, comparing with the same type of most existing mechanisms. [ABSTRACT FROM AUTHOR]

Design strategies for foldable mechanisms have been developed with inspiration from origami. In this study, we investigate a new direction that blocks are folded in a way that origami folds as the ori-blocks to generate a new type of foldable mechanisms consisting of multiple blocks. During the investigation, we propose a design approach to construct ori-blocks dissected from cylinders and cones, where "ori" is derived from the word "origami" in its original meaning as "folding". In this way, we cut the solids into six portions and assign rotation axes to assemble the portions into movable blocks. Interestingly, this connects the Bricard classical linkages developed in 1897 to these ori-blocks with coincidence of the position and orientation of the axes when the blocks are replaced by links. The study bridges the gap between ori-blocks, origami, and mechanisms, which proposes a set of novel reconfigurable mechanisms as ori-blocks. As spatial linkages have been widely used in a broad range of technical fields, we anticipate that ori-blocks will find several potential applications owing to their kinematics in reconfigurability. [ABSTRACT FROM AUTHOR]

Planetary gear set (PGS) has been one of the best components to constitute a transmission configuration, including the dedicated hybrid transmission (DHT). Using different synthesis approaches, the DHT configurations can be obtained through algorithms. However, different synthesis results correspond to different connection states of the planetary gear system. There are a certain number of results that violate the motion requirements of the mechanical principal need to be detected and removed. Therefore, this paper presents a novel modeling method to systematically remove the interference structures, with graph theory in structural synthesis. Based on the original graph theory, this paper proposes an equivalent replacement modeling method to convert the motor graph model into a brake-like graph model. Based on the conversion, avoid the appearance of the hanging points in the graph model. By applying the proposed approach, a DHT structure proves the feasibility of the method. The proposed detection approach can systematically detect all the PGS-based transmission with multi-PGSs, multi-shifting elements, and multi-power sources. [ABSTRACT FROM AUTHOR]

The identification of Baranov chains is associated with the rigid subchain identification problem, which is a crucial step in several methods of structural synthesis of kinematic chains. In this article, a systematic approach for the detection of rigid subchains, based on matroid theory, is presented and proved. Based on this approach, a novel method for the enumeration of Baranov chains is proposed. A novel algorithm is applied to a database of nonisomorphic graphs of nonfractionated zero-mobility kinematic chains. By means of the proposed algorithm, the previous results for Baranov chains presented in the literature with up to 11 links are compared and validated. Furthermore, discrepancies in the number of Baranov chains with up to 13 links, presented in the literature, are pointed out, discussed, and the proven results are presented. Finally, the complete family of Baranov chains with up to 15 links is obtained. Examples of application of the proposed method are provided. [ABSTRACT FROM AUTHOR]

Harmonic drives are widely used devices in robotic and space applications. As for any device transmitting motion, its mechanical efficiency is one of the main concerns for the designer. In this paper, it is proposed a new model to estimate this significant feature. The proposed approach makes use of the kinematic correspondence between the harmonic drive and an epicyclic gear train. Although the authors introduced simple approximations to describe the complex tribological phenomena during harmonic drive teeth meshing, the numerical results match the trend of experimental evidence. In particular, assuming the harmonic drive working at the rated torque, the plots of the mechanical efficiency versus different parameters such as temperature and angular speed have been simulated. [ABSTRACT FROM AUTHOR]

This paper presents an intuitive approach for mobility analysis of thin-panel origamis based on a coplanar 2-twist screw system, which consists of a pair of parallel/concurrent line vectors. In this study, we first proved that in any thin-panel origami, the allowable instantaneous mobility for any two facets connected to a third one can be described by a coplanar 2-twist screw system because this mobility is generated by two coplanar creases in the third facet. Second, the mobility of the basic origami units with a single facet loop was analyzed by using this coplanar 2-twist screw system. Third, the mobility analysis approach was extended to analyze the mobility of other planar/circular arraying origami patterns with multiple facet loops; typical origami patterns such as leaf-fold, Miura-ori were subjected to this analysis process. Furthermore, we proved that the proposed approach can be applied to the mobility analysis of complicated origamis; this approach proved to be considerably more intuitive than the traditional approach for mobility analysis. [ABSTRACT FROM AUTHOR]

Motion-force interaction performance analyses of redundantly actuated and overconstrained parallel robots with closed-loop subchains are an open problem considering two challenges: (a) how to take all the internal wrenches into account at the same level when the mobile platform suffers uncertain loads and (b) how to disclose the influence of the structural parameters inside the closed-loop subchains on the robot's performance. To tackle this problem, based on the blocking-and-acting strategy, this paper proposes a new screw-based method to analyze the motion-force interaction performance of such parallel robots. Two aspects of performance are focused, i.e., the distal and proximal motion-force interactability. The two proposed indices focus on reflecting the load-carrying capacity and the motion-transmission capacity, respectively. To evaluate the comprehensive performance of the parallel robot at a certain pose, a local interaction index (LII) is defined as the minimum value of indices of the minimized distal and proximal interaction performance. The feasibility and validity of the proposed indices are illustrated by the motion-force interaction analysis of some redundantly actuated and overconstrained parallel robots with closed-loop subchains. [ABSTRACT FROM AUTHOR]

Kinematic reliability of robotic manipulators is the linchpin for restraining the positional errors within acceptable limits. This work develops an efficient reliability analysis method to account for random dimensions and joint angles of robotic mechanisms. It aims to proficiently predict the kinematic reliability of robotic manipulators. The kinematic reliability is defined by the probability that the actual position of an end-effector falls into a specified tolerance sphere, which is centered at the target position. The motion error is indicated by a compound function of independent standard normal variables constructed by three co-dependent coordinates of the end-effector. The saddle point approximation is then applied to compute the kinematic reliability. Exemplification demonstrates satisfactory accuracy and efficiency of the proposed method due to the construction and the saddle point since random simulation is spared. [ABSTRACT FROM AUTHOR]

As a new type of gear transmission, composite curve-face gear transmission is used to transfer the power and composite motion of rotation and movement between the intersecting or interlaced axis. By using the theory of gear meshing, geometrical differential and space cam design, the motion principle and form of the composite curve-face gear transmission were discussed; the movement characteristics of the composite curve-face gear transmission were analyzed, including transmission ratio, rotation, movement and quick-return; the motion stability of the curve-face gear with different pitch curve forms was studied; and the forms of curve-face gear to realize stable and high-speed transmission were obtained. The correctness of the curve-face gear transmission is verified by experiment.

Variable stiffness actuators (VSAs) are a new generation of robotic drives that are developed to enhance the robot's ability to safely interact with unknown and dynamic environments. Furthermore, stiffness adjsutability can enhance energy efficiency in some particular applications, e.g. periodic motions with different frequencies. To adjust the stiffness, different mechanisms have been implemented in VSAs, each to fulfill the requirements of different applications with certain determinants. This paper explains these determinants and presents a comprehensive framework to systematically analyse performances of different stiffness adjustment mechanisms. First, a classification of different stiffness adjustment mechanisms is presented. Then, characteristics of each class regarding different determinants are evaluated and compared through numerical analysis. This will give additional insights into intrinsic pros and cons of different classes of stiffness adjustment mechanisms that enable a systematic future development of variable stiffness actuators and their applications. [ABSTRACT FROM AUTHOR]