Advances in Reconfigurable Mechanisms and Robots I

In this work the metamorphic structure representation (MSR) is proposed for the systematic development and evaluation of structures of metamorphic serial manipulators. The basic elements of MSR are presented, in terms of module and connection type. The conceptual design of metamorphic structures using MSR is presented. The criteria for evaluating emerging structures are introduced in terms of simplicity and solvability of inverse kinematics. Finally, a case study of two different structures is presented along with their subsequent evaluation.

The metamorphic mechanism has the characteristics of multi-configuration, variable constraints, and multi-function. For achieving the variation characteristics of the topological structures in different configurations and the coupling relations intuitively during the process of configuration transformation, a novel comprehensive symbolic matrix for representing the topological structures of the metamorphic mechanism is proposed. The information including variation of components, the relative joint orientations is involved in this new adjacency matrix. The variation characteristics and coupling features of the metamorphic mechanism can be obtained by the generalized operations including intersection and difference on the corresponding symbolic matrices.

This paper relates two problems: enumeration of metamorphic robots in mechanical engineering and enumeration of polyforms in mathematics. First, a review of the two problems is presented. Some particularities of the enumeration of metamorphic robots and theoretical results about the enumeration of polyforms are described in order to create a bridge between these problems. Then, based on the results and the complexity of the enumeration of polyforms, some directions for further works on the planar enumeration of metamorphic robots are proposed.

Based on the original Koenigs joint, we present a novel discontinuously movable (DM) RC-//-RC parallel mechanism having a bifurcation of motion. At a singular posture of bifurcation, the end effector has locally two degrees of freedom of infinitesimal translation and two working modes happen at the positions of double points on intersections of two congruent revolute cylinders, which are generated by the two RC open sub-chains. In the mode I, two axes of rotations are transmitted by the ratio of minus one and two shafts rotate in an opposite direction. In the model II, angular velocity ratio between two intersecting shafts is positive one and two cranks rotate in the same direction. Moreover, the same type of phenomenon occurs when two RC open chains are displaced by an offset of translation. Last but not least, a further investigation on a general DM chain of RC-//-RC or HC-//-HC type is expected.

For Wohlhart’s double-Goldberg 6

R

linkage constructed from two original Goldberg 5

R

linkages, there are two constructive forms and one non-constructive form, which can be reconfigured through bifurcation points. A special Wohlhart’s double-Goldberg 6

R

linkage is proposed by introducing a special geometry constraint. One of the constructive forms of the resultant linkage is degenerated into a pseudo 4

R

linkage, which is essentially a Bennett linkage. Therefore, the special Wohlhart’s double-Goldberg 6

R

linkage achieves multiple forms among 4

R

and 6

R

linkages. Physical models are also made to validate the special Wohlhart’s double-Goldberg 6

R

linkage in different operation forms.

The practical metamorphic process, which include configuration transforming, configuration keeping and working sequence problems, is introduced. The concept of equivalent resistance gradient of metamorphic joints is proposed to investigate a new way for regulating the constrained metamorphic process and/or design of metamorphic joints. A kinds of metamorphic cyclogram is introduced, and the resistance characteristics of typical metamorphic joints are studied. A non-dimension equivalent resistance coefficient of metamorphic joints and the equivalent resistance gradient model of metamorphic mechanism are defined. The connection ships of equivalent resistance, constraint characteristics and forms, and the structure of metamorphic joints in the working stages are revealed. A design approach is demonstrated based on the metamorphic cyclogram and the equivalent resistance gradient model.

A novel electric loading mechanism is introduced in this paper by applying metamorphic mechanisms to the innovative design of loaders, which can change its topological structure to satisfy various kinds of demands during the working process. One driving motor can finish multiple tasks such as shoveling, rolling, lifting, and unloading. This paper introduces the characteristics during the evolutionary process first, based on which, two 0-DOF (Degree-of-Freedom) directional Assur groups are developed to be the new metamorphic cells as well as their representations. Configuration transformation and its degeneration ways during the genetic growth are studied. Biological modeling for working-phase mechanisms is proposed. The evolutionary synthesis process for generating the source-metamorphic loading mechanism and its representation is introduced through evolutionary operations.

Mechanism with variable topologies (MVTs) can change its topological structure because the kinematic types of certain joints are changeable during operation process. This work reviews and discusses the matrix methods for the representation and analysis of the topological structures of MVTs. First, we study several matrix representation methods for MVTs and compare their characteristics. Accordingly, these methods are classified into two different types based on the existence of joint types recorded. Furthermore, we discuss the applications of these methods for the structural decomposition and the topological homomorphism identification of MVTs. Last, we summarize the current limitations of the matrix representation methods for MVTs for future studies.

Wooden puzzles consisting of interlocking assembly of notched sticks are often referred to as bar-puzzles, sometime known as the Chinese Puzzles or Chinese Cross. By far the more familiar of three-dimensional puzzles in general is the multi-piece bar. But there does not appear to be any evidence that the idea of its mechanism property and any configuration analysis originated. To this purpose, this paper proposes a static and discrete reconfiguration theory of geometric puzzles for modeling the topology changement as Put Together, Take Apart, Sequential Movement and various others. The partition and assembly process analysis aims to extract the kinematic chains as links and joints. The puzzle unlocking leads to configuration constraints rearrangement problems which accompanying pieces of bars self-grouped as defined reconfiguration links and joints. The puzzle solutions are first described as reconfigurable topology mechanism and the constrained mobility is analyzed based on an ingenious and distinctive reconfiguration property.

This paper investigates the use of an agent based assembly strategy for a wind turbine hub. The manual assembly procedure for a wind turbine is presented. The hub parts are constantly optimised and therefore a fully automated assembly line requires continously reprogramming. Thus, a new reconfigurable assembly system is introduced which is flexible and self-adaptive. The methodology of implementing an intelligent agent for designing the assembly strategy for the wind generator hub and the algorithm for the optimal task sequence are described. This reconfigurable automation runs a Partial Order Planning algorithm in real-time using Beckhoff TwinCAT

®

3.

In the curriculum of mechanism design, degree of freedom (DOF) is by far one of the most important issues, but it is not easy to whether impart from teachers or learn for students, especially it needs strong space imagination to determine the freedoms and constraints. To make this teaching or learning more convenient, an education kit is no doubt helpful to understand the complicated concept and theory via demonstration or DIY. For this purpose, a design philosophy for a reconfigurable compliant education kit is proposed, and a prototype is provided correspondingly. In fact, this education kit can be assembled into a variety of different parallel flexure mechanisms, which can be derived by Blanding’s rule. The education kit shows its advantages in the following applications: (1) demonstrate the complementary rule of freedom and constraint proposed by Maxwell; (2) identify the redundant constraints; (3) analyze degree of freedom in both a qualitative and quantitative way; (4) develop the design of a specific compliant mechanism with multiple topologies.

In this paper, a systematic approach is presented for the structural synthesis of a class of metamorphic parallel mechanisms which possess variable mobility. The metamorphic parallel mechanisms are constructed using limbs with lockable joints. When different joints are locked, the mechanisms will have different mobility from single degree of freedom to full six degrees of freedom. First, the feasible limbs are enumerated based on constraint analysis. Then a metamorphic parallel mechanism constructed with feasible limbs is presented as example and its ability to perform variable mobility is demonstrated. The metamorphic parallel mechanisms presented in this paper will be perfect suitable in the complex process of industrial production.

This paper presents adjacency matrix originated three-dimensional matrix for structural representation of mechanisms by integrating binary string in the sense of displacement subgroup theory. The improved elementary matrix operation for expressing of topological transformation of metamorphic mechanism is integrated in the three-dimensional matrix representation. A novel reconfigurable eight-bar linkage employing variable-axis revolute joints is proposed and the three-dimensional matrix for each working phase is expressed to reveal the distinct geometry. The improved elementary matrix operation is used to express the topological transformation of a metamorphic eight-bar linkage and to identify the effectiveness of the operation.

Traditional loaders are mostly hydraulic type, of which there exists some problems like high costs of manufacturing, assembling and maintaining. A novel type of electric loader with the ability to change its topological structures to satisfy various kinds of needs in the working process is proposed. One driving motor can finish multiple tasks such as shoveling, loading, lifting, and unloading. This paper introduces the source-metamorphic mechanism of the newly invented loading mechanism, as well as its metamorphic ways to achieve variable topology. The adjacency matrix and topological graphs are used to describe topological change of each working phase, based on which the principles and characteristics of configuration changing are analyzed.

By analysing the work process of self-help chair for the old, combined with the topology analysis, calculated the degrees of freedom in each phase. This page elaborated on the analytical methods of composite hinge in topological diagram, and provided a design example and analytical samples for further research of metamorphic theory and analytical method.

New concepts such as the variable graph, the invariant subgraph, the variable subgraph and the cell-variator etc. of Metamorphic Mechanisms or Variable Topology Mechanisms are put forward and defined for the first time in this paper. Three new theorems on composition of the variable graph and one new theorem on the equivalent transformation of the incidence relation cell-variator are found out and their validity is strictly proved. The classifications of the cell-variators and the diagram representations of three kinds of cell-variators are studied. The diagram representation and adjacent matrix representation of the variable graph are given. The variable graph provides useful new tool for the topological structural analysis and synthesis of metamorphic mechanisms or variable topology mechanisms. It has great scientific value and engineering practicality.

This paper presents a method of type synthesis for planar parallel mechanisms (PPMs) incorporating actuated limbs with zero/one constraint with set conception. Firstly, according to their contributions to the moving platform, the limbs of PPMs can be classified as four categories: actuated limb with zero constraint, fully-constrained limb with zero actuator, fully-constrained limb with one actuator and under-constrained limb with one actuator. Followed by the descriptions of actuated space and constrained space for the end of the limbs by virtue of the screw theory, the type syntheses of the four type limbs are carried out. Then different sets and functions are defined respectively, whose elements and variables are the topologies of four type limbs. The different function values and the composition principle of PPMs lead to existence of PPMs topologies by four solutions. Finally, taking three typical PPMs with linear motors for examples, their virtual prototypes are obtained with commercial 3-dimensional CAD software.

Static and dynamic model of self-adapting impacted and contractile mechanism of crawling robots on cone lamp pole are built, also contact force and contract action of pressing mechanism are simulated and analyzed in COSMOSMotion. Research shows that the mechanism compacting force on the pole is evenly distributed when applied at constant force; corresponding relationship of the contracting force and caliber is given, which provides the design basis for the robot crawling with the constant force.

This paper deals with the deformation function of the flexspline under load condition, and its effect on the tooth profile. In order to investigate the deformation discipline under load condition, a kinematic simulation analysis model of ABAQUS for a harmonic drive with engagement output is established. With this model, the nodal displacements of the flexspline neutral layer under different loads are obtained in dynamic transmission process. Fourier function is adopted to fit the deformation function under loads. Based on the deformation function, the tooth profile of the circular spline is modified. The example indicates that with the modified tooth profile under load condition the conjugate region increases, and the deformation function varies little. The work of this paper lays the foundation for optimizing the tooth profile to prolong service life of harmonic drives.

Steering is one of the important systems of an automobile. Ackermann mechanism is popularly used in all the automobiles. Though advances such as power steering have been taking place in providing steering to automobiles, the basic mechanism is Ackermann mechanism only. The Ackermann mechanism does not provide perfect steering conditions. However, it is popular because it involves only revolute pairs in the mechanism. In this paper an attempt is made to propose a new steering mechanism which is simpler than Ackermann mechanism and provides perfect steering always.

In this paper, a

tetrahedron unit

constructed by connecting three links to a node via revolute joints is proposed. A closed loop mechanism is constructed by combining two tetrahedrons units to share a common face with three spherical joints such that the geometric structure of the mechanism is a triangular bipyramid. We show that the structure of the mechanism enables it possess a rolling function when proceeding on the ground. Furthermore, with the similar topology structure, two more closed-loop rolling mechanisms are obtained by combining 4 and 6 units, respectively. Due to the similar rolling principles of the proposed mechanisms, it suffices to analyze the rolling feasibility of the triangular bipyramid mechanism. By analyzing the kinematics, the deformation features of the mechanism are obtained. Upon some proper controls, we show that these features enable the mechanism to roll and switch directions when it proceeds on the ground. These functions are verified by a series of simulations with a 3D model and experiments with a prototype.

Compliant multistable mechanisms, which are capable of steadily staying at multiple distinct positions without power input, have many potential applications in switches, valves, closures, relays, statically-balanced mechanisms, reconfigurable robots, and large-displacement micro actuators. In this paper, we propose a new idea of utilizing metamorphic transformations to develop compliant multistable mechanisms. By distributing the prescribed stable equilibrium positions into different metamorphic working phases, the design of a compliant multistable mechanism can be greatly simplified. The idea is demonstrated by a tristable mechanism that can metamorphically transform from a compliant 5-bar mechanism into a compliant 4-bar mechanism in a certain range of motion. The kinetostatic solution of this tristable mechanism is formulated and the kinetostatic results confirm that the mechanism has two deflected stable equilibrium positions besides its initial assembly position, with one occuring in the 4-bar working phase and the other in the 5-bar working phase. Although the discussion is limited to a planar 5-bar mechanism, the idea of utilizing metamorphic transformations to achieve multistable behivors can surely be extended to other types of linkages.

This paper deals with the type synthesis of partially decoupled 2-DOF parallel mechanisms with two 1T1R (one translation and one rotation) operational modes—a novel class of reconfigurable parallel mechanisms which can switch operational modes without disassembly. In the two 1T1R operational modes, the axes of rotation of the moving platform are different. A bi-mode revolute joint is defined to simplify the representation of motion patterns of the moving platform. Using the vitual-chain approach, the type synthesis of partially decoupled 2-DOF 1T1R parallel mechanisms and partially decoupled 2-DOF parallel mechanisms with two 1T1R operational modes is carried out. The proposed mechanisms need one less actuated joint than the existing parallel mechanisms with two 1T1R operational modes. This work provides a solid foundation for developing energy-efficient parallel mechanisms with two 1T1R operational modes.

This paper presents reconfiguration with mobility change of a class of metamorphic parallel mechanisms consisting of three reconfigurable rT

PS

limbs with parallel bracket rotation axes. Stemming from the reconfiguration of the reconfigurable Hooke (rT) joint, the rT

PS

limb has two phases with one having full mobility and the other giving a constraint force to the platform based on the constraint screws. The platform constraint screw systems show that the new metamorphic parallel mechanisms have four topologies by altering the limb phases with mobility change among 1R2T (one rotation with two translations), 2R2T, 3R2T and mobility 6. Special topologies are identified considering the limb arrangement. Following these, actuation scheme is discussed by covering all the topologies of the metamorphic parallel mechanisms based on constraint screws.

Using topological structure synthesis method based on the Position and Orientation Characteristic (POC) set, 26 kinds of 3-translation parallel mechanisms are synthesized, and 19 of which are presented for the first time. This method may be applicable for both topological structure synthesis of non-over-constrained and generally over-constrained mechanisms.The geometric and physical meaning of this method is clear and easy to understand for designers.

In this paper, a novel Reconfigurable Spherical Motion Generator is proposed. The aim of the proposed redundant parallel manipulator is to provide unlimited spherical motion. The conceptual design is first presented and followed by three different prototypes. The motivations of each prototype are explained and the structures of each prototype are described in detail. During the development of RSMG, different problems have been addressed and solved by the following up prototypes.

This paper presents a new method for the topological reconfiguration of a parallel robot. Using the existing structure of a full six degree-of-freedom parallel robot, limited mobility modes can be realized easily without the need to remove branch modules from the robot structure. Instead, branch modules are reconfigured from an unconstrained-active to a constrained-passive state by means of hybrid active/passive motors and reconfigurable universal-to-revolute joints. In doing so, the robot is capable of assuming a configuration that uses only the degrees-of-freedom required to complete a given task. However, due to the system setup, there are multiple candidate configurations available, each with its own workspace and reach capabilities, thus guidance is needed in selecting the appropriate configuration. An isomorphic and workspace analysis are performed to identify the capabilities of each configuration. To accomplish this, a branch-based mobility analysis, and a parametric kinematic constraint equation are formulated. It is shown that limited mobility modes with different isomorphic configurations can be synthesized automatically with this method.

This paper presents a type-changeable kinematic pair with variable topology. The geometry properties and topological phases of the type-changeable kinematic joint are revealed. A novel reconfigurable parallel mechanism is evolved from the type-changeable kinematic pair according to geometric conditions of assemblages for parallel mechanisms. The platform of the reconfigurable parallel mechanism is capable of implementing various functions accompanying to the phase change of the integrated type-changeable kinematic pair. The platform has 6 DOFs in the source phase and can change its mobility to 5, 4 and 3. Experiments have been carried out for identification of a 3R

e

PS

e

subphase controller.

As manufacture trends move towards life-cycle design, sustainable production, geometrical complexity, short time-to-market, small and variable batch production and mass customization; manufacture equipment struggles to keep pace and provide the required flexibility, adaptability and automation. This paper describes the new concept of self-reconfigurable intelligent swarm fixtures. Following the conception of this new fixturing system, it arises under European commission 7th framework programme the SwarmItFIX project that gives an application and an insight towards the new fixture technology. The paper gives a description of the solution developed in SwarmItFIX focusing on the physical prototype demonstrator constructed to validate the concept as an intended new fixture benchmark for manufacturing sheet metal panels.

Traditional bionic joints including wrist, waist, ankle and shoulder have three revolute degrees of freedom, which can be treated as spherical joints, and its structure is prone to be damaged with impact force through the center of spherical joint. In this paper, a novel metamorphic parallel mechanism with two configurations used for bionic joint design is presented. The origin kinematic chain for this metamorphic mechanism, which is also the first configuration mechanism, consists of a moving platform, a base plate and four connecting legs between moving platform and base plate. In contrast with traditional ankle joint, a constrained translational degree of freedom can be activated in origin kinematic chain to avoid impact damage. The origin kinematic chain can transform to the second configuration mechanism which is in possession of three revolute degrees of freedom and equivalent to normal spherical joint. The transforming process is represented by new incidence matrix and the motion characteristics of this metamorphic mechanism in different configuration corresponding to each work-stage are analysed using screw theory.

Although numerous PKM topologies have been invented recently, few of them have been successfully put into production. A good topology can only provide good performance unless its geometrical parameters are optimized. This paper studies the dimensional synthesis of a new PKM which has shown great potential for large volume high performance manufacturing. A new optimization approach is proposed for design optimization, with a new performance index composed of weight factors of both Global Conditioning Index (GCI) and actuator stroke. Maximizing GCI will ensure the effectiveness of the workspace, while minimizing actuator stroke leads to reduced machine cost and increased efficiency. Results show that the proposed optimization method is valid and effective. The PKM with optimized dimensions has a large workspace to footprint ratio and a large well-conditioned workspace, which ensures its suitability for large volume machining.

This paper presents a detailed study of the instantaneous kinematics of the 5-

R

SP

parallel mechanism with centralized motion. The study uses screw theory to investigate the mobility and the singular configurations of the mechanism. The constraint-screw set of the platform is obtained from an analysis of the motion-screw sets comprised by each kinematic chain. The analysis shows that the platform has a screw motion, that is, a one degree-of-freedom motion consisting of a rotation and a translation about an invariant axis. The motion-screw sets are also used to obtain the Jacobian matrix of the mechanism which provides closed-form solutions for the inverse and forward instantaneous kinematic problems. This matrix also provides insight into the singular configurations by investigating the constraint-screws and the motion-screws of the platform in these configurations. Finally, two numerical examples and a motion simulation of the mechanism are presented to illustrate the significance of the analytical results.

To reveal the modal properties of a 3-dof PKM module, a wire-frame model is proposed and relative experimental modal test is conducted. The lower orders of natural frequencies, damping ratios are obtained and corresponding mode shapes are classified. The modal analysis reveals two categories of vibration modes for the PKM module. The first to the third orders of modes correspond to the overall vibration of the module while the fourth to the sixth orders of modes corresponding to pitch and yaw as well as their combination of the moving platform. The overall vibration modes of the module are expected to be eliminated through bolt-connection of the base and fixed frame. The moving platform vibration modes, however, rely on the weak stiffness of spherical joints. Thus, desirable dynamic performance of the PKM module demands delicate design for the spherical joint with high stiffness.

The motion character of a special three degree-of-freedom (DOF) parallel mechanism is analyzed by screw theory. This mechanism’s significant feature is that the axis of its prismatic pair is parallel to that of its revolute pair in the same limb. Firstly, by analysis, the mechanism’s constraint screws are obtained, which leads to motions along the fixed-length links being restricted. Secondly, we get the mechanism’s constraint screws’ reciprocal productions, namely the mechanism’s free motions, which are three screw motions. After that, a numerical example is presented to illustrate the analysis in detail. At last, we draw some conclusions and discuss the future work.

This paper proposes an approach to analyse comprehend the effect of different uncertain ground impedance parameters on bipedal walking. A dynamic model of a rimless wheel in contact with an unpredictable visco-elastic terrain is presented. The mathematical model of the rimless wheel as it makes contact with an uneven ground has been developed based on Lagrangian dynamics. The uncertain ground impedance parameters induce structural visco-elasticity which is represented by a spring and damper pair in the horizontal direction and another in the vertical direction. A numerical simulation has been performed to investigate the behaviour of the proposed dynamic mathematical model. The results describe the effect of the interplay among the visco-elastic parameters at the ground-leg contact point of a legged walker and the emerging properties of interaction dynamics of walking on different impedance parameters. The results of simulation trials highlight the importance of the above interplay in the area of bipedal humanoid walking.

Metamorphic mechanisms with two distinct behaviors were designed using compliant mechanism theory with a potential application as a prosthetic knee. The mechanism has discrete “locking” points to restrict rotation when under a compressive load. The designs use cross-axis flexural pivots, either in inversion or isolation, with engaging teeth to carry loads at distinct angles. Inverted compliant mechanisms function by inverting the mechanism so the compliant members are in tension when a compressive load is applied. Compliant mechanisms in isolation provide an alternative loading pattern which redirects the load to a passive rest. The mechanism incorporates teeth which engage during weight-bearing in flexion at up to 60° of flexion to lock the mechanism. When tension is applied to the device, the teeth are disengaged and the mechanism is allowed to rotate freely. The purpose of this design is to hold compressive loads both when un-flexed and flexed. The concept is applied in the preliminary design of a prosthetic knee joint. Proof-of-concept prototypes successfully demonstrate the metamorphic behavior.

This paper presents the design of a new inherently compliant actuator intended for the development of a knee exoskeleton. The proposed actuator has the ability to reconfigure the level of stiffness in order to achieve suitable torque-to-angular displacement profiles for different human tasks and users. The design specifications of the actuator have been obtained from motion capture and simulation data of sit-stand-sit motion cycle. The actuator functional principle and modeling are presented. Finally the mechatronic design of the actuator is described.

This paper proposes a dynamic model utilizing continuum arms to form a reconfigurable robotic system. The continuum arms are composed of serially-linked parallel mechanisms inspired by octopus arm anatomy. The kinematics and dynamics for a single continuum arm are formulated and then expanded to a multiple arm system using a modular modeling method. Simulation results show that this robotic system is capable of diverse locomotion patterns by changing the configuration of the arms.

Surgical instruments with multi-degree of freedom (DoFs) are widely used in single-port surgery and natural orifice transluminal endoscopic surgery. In this paper, a novel reconfigurable unit, which can be used as a basic component of a high dexterous surgical instrument (HDSI), was developed according to an isosceles trapezoid mechanism. Then the unit was improved and optimized to obtain a larger rotational range. The new unit can prevent driving cable from slackening during the moving. Two multi-joint prototypes, which are designed based on the proposed reconfigurable unit, are developed and experimented preliminarily. Experiment results show that the unit can avoid cable slack and is suitable to be used for HDSI.

The MR-compatible robot for needle insertion has attracted increasingly attentions due to high precision in minimally invasive surgery. A robotic system for prostate brachytherapy has been designed and is actuated by five ultrasonic motors to realize needle orientation and insertion. The application of cable transmission leads to a compact and dexterous mechanism, because all the motors are placed in the base and the moving part of the mechanism becomes as light and small as possible. What’s more, placing the motors far away from the center of the scanner will eliminate artifacts and distortion of the MR images caused by the motors. The displacement analysis is carried out and the reachable workspace is obtained. Jacobian matrix is deduced in velocity mapping model for dimensional synthesis in further study. Configuration singularities are analyzed on the basis of Jacobian matrix.

Through investigating a 1-year-old human baby’s body and crawl movement, an infant-sized quadruped robot “Babybot” is designed. The robot has a mechanism of two passive DOFs in its waist, namely the flexible waist. The biologically-inspired Central Pattern Generator (CPG) is employed for controlling Babybot’s locomotion. The results of dynamic simulation show Babybot can crawl in a natural infant-like way and the flexible waist can improve the robot’s crawling performance.

Minimally invasive robotic surgery has many advantages over traditional open surgery and laparoscopic surgery, though current minimally invasive surgical (MIS) robots have significant drawbacks, including large volume and weight. This paper presents a new arrangement of a multi-degrees of freedom (DOF) MIS robot to maintain portability while incorporating a reconfigurable structure to achieve improved output force and stiffness. The performance and design of the reconfigurable structure are also optimized. Performance analysis shows this new reconfigurable robot can achieve a sufficiently large workspace and output forces for MIS.

This paper presents a novel portable passive robotic platform for three-dimensional scanning (3DS) of soft tissue, capable to evaluate mechanical properties and geometry in ex vivo condition. The platform comprises six degrees of freedom (DOF) passive robotic arm (Phantom Omni), a data acquisition system and a set of stiffness probes for force and stiffness measurement. The performance of the developed platform was validated by sliding indentation and uniaxial tissue indentation measurements on silicone phantoms, porcine organs and human prostates. The results show that the platform can perform effective measurements of soft tissue mechanical properties and help surgeons to identify embedded tumours.

The goal of this paper is to introduce scaffolded DNA origami as a viable approach to the design of nanoscale mechanisms and machines. Resembling concepts of links and joints in macro scale mechanisms and machines, we propose the concept of

DNA Origami Mechanisms and Machines (DOMM)

that are comprised of multiple links connected by joints. Realization of nanoscale machines would pave the way for novel devices and processes with potential to revolutionize medicine, manufacturing, and environmental sensing. The realization of nanoscale machines and robots will enable scientists to manipulate and assemble nano objects in a more precise, efficient and convenient way at the molecular scale. For example, DNA nanomachinery could potentially be used for nano manufacturing, molecular transport in bioreactors, targeting cancer cells for drug delivery, or even repairing damaged tissue. As a proof of concept, we build a nanoscale spatial Bennett 4-bar mechanism that can be completely folded and unfolded with a specified kinematic motion path. The links comprise a 16 double stranded DNA (dsDNA) helices bundled in a 4 by 4 square cross-section yielding a high mechanical stiffness. The joints (in this case hinges) are designed using single strand DNA (ssDNA) connections between the links. This DOMM was designed within caDNAno, a recently developed computer-aided DNA origami design software, and then fabricated via a molecular self-assembly process. The resulting structure was imaged by transmission electron microscopy to identify structural conformations. Our results show that the designed DNA origami Bennett mechanism closely follows the kinematics of their rigid body counterparts. This research has the potential of opening a new era of design, analysis and manufacture of nanomechanisms, nanomachines and nanorobots.

This paper presents an application of the virtual prototyping on the reconfigurable mechanisms and in particular, in this study, is shown a multibody origami carton folding model. The aim of this work is to reproduce via numerical model the D-RAPS reconfigurable multifinger robot that is in use for this kind of application. Thanks to the trajectory matching, the authors reach model validation only by comparing analytical and numerical results. In addition, this model permits to investigate the carton folding deeper than via experimental tests. In fact, as example, the contact forces between the mechanism finger and carton panel are computed.

Unstructured environments are challenging for conventional robots, and modular self-reconfigurable robots (MSRs) can be deployed to overcome this challenge. The goal of the current work was to develop a flexible, cost effective multi-module robot system capable of self-reconfiguration and achieving various gaits in unstructured environments. This paper discusses the communication aspects of the Modular Robot for Exploration and Discovery (ModRED) robot system from a hardware perspective. To ensure enhanced flexibility and local autonomy as well as better reconfiguration, each robot module is built with four independent degrees of freedom, and a novel docking interface provides interconnection of modules. The prototyping effort is described with emphasis on the implementation of inter-module communication. The electronic hardware layout and control system are described, and the communication system is outlined. Finally, some preliminary testing of the developed prototype is presented.

Reconfigurable robot is a mechatronic device that can change its own shape. Such robots are not only designed to perform a specific task but also to execute multiple tasks by changing their shape and size. In order to change their own shape, reconfigurable robots are built from multiple identical modules that can rearrange themselves to form a large variety of structures. Based on module specifications, the potential ability of the complete robot is determined. Further, module specifications in turn determine the functional reconfiguration of these robots which increases the adaptability against the change of environment. Hence, accurate movements of module are needed, but this may be extremely difficult due to the errors inherent within the control system. In this paper, structures and characteristics in self-reconfigurable robots towards change in environment are investigated. A comprehensive survey of available literature is done to identify key challenges and opportunities in this area.

The locomotion of multi-legged robots has some characters similar to metamorphic mechanisms. Assuming the constraints of the feet on the ground with hinges, the supporting legs and the hexapod body are taken as a parallel mechanism, and each transporting leg is regarded as a usual serial manipulator. In different period there may been different equivalent mechanisms of multi-legged robot. The locomotion of hexapod robot can be considered as a series of varying hybrid serial-parallel mechanisms. Four typical 3 + 3 gaits of a radial symmetrical six-legged robot are studied in this paper based on metamorphic theory. A new static stability workspace is proposed to establish the static stability of four gaits, and a new method to calculate the stride length of multi-legged robots is present by analyzing the relationship between the workspaces of two adjacent equivalent parallel mechanisms in one gait cycle.

A method of automatic dynamics generation for modular robots is presented on modular level. The robot’s link parameters are got from the modules’ parameters and the Assemble Incidence Matrix (AIM) describing the module types, assembled orientations and sequence of a given robot configuration. Adjoint matrices are adopted to describe the forward mapping of velocities, accelerations from frames on the (

i

−1) link to that of the

i

th link, as well as the dual adjoint matrices are taken to describe the backward mapping of moments and forces between frames on the

i

and the (

i

−1)th links. A mathematically consistent recursive approach for dynamics of modular robot is got from the Newton–Euler formula in Lie Group form.

Modular robot technology is of great significance for developing service robots and promoting its industrialization. This paper presents a kind of modular robot architecture which is composed of the Robot Operating System (ROS), standard bus and modular functional components with standard interfaces. The robot has advantages of openness, compatibility, separated function of hardware and software. With this robot, the paper presents the challenges for developing modular robots and explores the uniform software platform for developing modular robots with ROS and integration technology. With this development, this paper presents a way for integrating the functional components of software and hardware into various robots.

This paper introduces a Chinese massage robot metamorphic end-effector composed by parallel and serial mechanism, the numbers of whose driving elements, driven elements and kinematic pairs are variable, which can work in four different ways of Chinese medical massage techniques. In this paper, the principles of motions, mechanism composition, motion characteristics, metamorphic methods and configuration variable changes of four common massage techniques are analyzed. This metamorphic end-effector has been used in a National High Technology Research and Development Supported Program in China.

This paper proposes a skating locomotion mode of a novel quadruped robot with extendable body and passive wheels. The kinematic model and skating principle have been analyzed according to the character of the robot’s special structure. The gaits of straight skating and steering skating are discussed in detail. Lastly, we make some simulations to verify the skating principle and the kinematic analysis above.

Combining the modularization and reconfigurable ideas, a quadruped/biped reconfigurable walking robot with parallel leg mechanism is presented. According to design requirements, structural parameters of quadruped/biped walking robot are determined and numeric area of them and the relationship between them are analyzed. The requirements of walking velocity and bearing capacity of quadruped/biped walking robot are taken as measurable indexes to analyze the dexterousness, global minimum velocity index and bearing capacity index, and obtain the optimum numeric area of every parameter, which lay the theoretical foundation for manufacturing of prototype.

In this paper we propose a new iterative algorithm for effective contact information identification, allowing a fingertip equipped with 6-axis force/torque sensor to accurately estimate contact information, including the contact location on the fingertip, the direction and the magnitude of the friction and normal forces, the local torque generated at the surface. The proposed algorithm is highly computational efficient and achieves an update rate of 833 Hz. The accuracy of the proposed algorithm has been validated experimentally. The results show that the algorithm provides precise estimation for all the identified contact properties.

Handling of objects with irregular shapes and that of flexible/soft objects by ordinary robot grippers is difficult. It is required that various objects with different shapes or sizes could be grasped and manipulated by one robot hand mechanism for the sake of factory automation and labour saving. Dexterous grippers will be the appropriate solution to such problems. Corresponding to such needs, we have developed an articulated mechanical hand with five fingers and 25 degrees-of-freedom which has an improved grasp capability. Since the developed hand is possible to envelope and grasp an object mechanically, it can be used easily and widely in the factory and for medical rehabilitation purpose. This work presents the conceptual design and the kinematic analysis of such a hand.

Human beings have flexible arms and legs that can ensure them conduct various challenging operations to work out daily requirements. Therefore, Humanoid mechanism design become hot research areas recently. To mimic the skeleton structure and driving scheme of a human arm, a 7-DOF cable-driven mechanism is determined to develop. Cable-driven mechanism allows actuators don’t have to be placed on joints that makes it possesses several advantages such as low weight, high dexterity, and large reachable workspace compared with traditional configurations. The forward and inverse displacement analysis issues are conducted. In this paper, dynamic analysis of the cable-driven humanoid arm (CDHA) is conducted based on Lagrange’s method. The dynamic model is established by making use of twist-product-of-exponential formula and the cable tension distribution analysis is also addressed. At last, both the dynamic model and the algorithm are validated through several simulations in MATLAB.

The collection of waste can be improved by adopting new methods of monitoring and new strategies for economic and efficient service. Over the past 200 years there have been no particular developments. Today you can reconfigure the systems for collecting, with the methods of robotic autonomous systems. It uses sensors to monitor the containers. Wireless communications and Internet are adopted to control the collection process. Statistical evaluations are performed to optimize the costs. Green waste Project strongly has reconfigured the process of waste collecting, with technical advantages and economic improvements.

This paper presents a decentralized controller based on third-order extended state observers (ESO) for reconfigurable manipulator with interconnection terms. Coupling interconnection terms of the joints and modeling uncertainties are estimated and compensated real-timely by using third-order ESO. Using particle swarm optimization (PSO), the parameters of ESO were adaptively adjusted. The controller is applied to the trajectory tracking control of 4-DOF reconfigurable manipulator. Simulation results show the effectiveness of the proposed method in treatment of the interconnection terms.

A decentralized control scheme based on a combined backstepping terminal sliding mode algorithm for reconfigurable manipulators is proposed. Based on Lyapunov stability theory, backstepping technique and terminal sliding mode are utilized in the first and second order of the subsystem respectively, the unknown terms and interconnection term are approximated or compensated by neural networks whose weights are updated with adaptive laws. For the serious chatter of the controller with the linear sliding mode, the terminal sliding mode replaced the linear sliding mode. In contrast, the method improves the convergence rate and the tracking accuracy, the control signal is smoother. Finally, the simulation results show the effectiveness of proposed scheme for different configurations with no need to modify any parameters.

This paper investigates the possibility of converting grasped objects from precision grasps to power grasps using a variable transmission ratio for an underactuated finger. Reconfiguration happens when the precision grasp converts to a power grasp, because the number of contact points changes which changes the topology of the grasp. To this effect, a variable radius pulley was designed. A simulation study is presented to analyse grasping behaviour and a potential energy method is used to predict the equilibrium positions of finger and object. With this method stable and unstable equilibrium positions are determined. This is followed by an experiment to verify the theory. This paper is a first step in dextrous manipulation with large movements of objects using underactuated fingers.

In this paper, an analysis of a master-slave control by force feedback based virtual impedance controller with time delay is conducted. Especially, the relationship between time delay and transparency is focused on. The proposed method consists of force feedback based virtual impedance controller of master manipulator and perfect tracking position controller of slave manipulator. From the controller analysis, it is confirmed that the relationship of “Reproducibility” and “Operationality” is simple in the proposed method and this makes clear parameter design of the controller as compared with conventional method. This is one of the remarkable points. Moreover, the proposed controller can be flexibly applied to many kinds of time-delayed teleoperation systems because models of a slave robot and communication time delay are not required. The validity of proposed controller is verified by some simulations.

Friction in tendon based robot hands has been an unavoidable problem. With introduction of more dexterous and metamorphic hands this intrinsically non-linear and highly time-varying force has become an obstacle to achieve high performances and required accuracy which the robot designers are aiming for. This paper proposes a method to tackle the problem by measuring friction and applying it in a feed forward loop. The novelty of the method is in the possibility to perform the task automatically and on a regular basis to compensate the time varying phenomenon.

Cable-driven manipulators are traditionally designed for general performance objectives, such as maximisation of workspace. To take advantage of the reconfigurability of cable-driven mechanisms, the optimisation of cable-configurations for specific tasks is presented. Specifically, two types of task specific objectives are explored, the minimisation of cable forces over a desired trajectory and the maximisation of workspace about a desired pose. The formulation and incorporation to the optimisation problem for both task specific objectives are presented. Illustrated using a 3-DoF manipulator example, the results clearly demonstrated the advantages of optimising cable configurations for specific tasks. The potential ease of relocation in cable attachments makes task dependent reconfiguration feasible.

Motion coordination is one of the key technologies that affect the stability and efficiency of robot. Animals’ motion must have the advantages reserved from long time’s evolution, which offers good prototypes for the control of robot. In this paper, the locomotion of quadruped animal,

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, was observed when trotting on the level, and the trajectories of feet relative to the hip on the same side were analyzed. Results showed that the speed of feet on stance phase relative to the hips were the same, feet accomplished the change of moving direction and speed during transition process between stance and swing phases. This approach was simulated in a robot mode and used in trajectory plan of a quadruped sprawling robot.

This paper describes the organization and teaching methodologies for mechanics and robotics related subjects in the European Erasmus Mundus master programmes EMARO (European master in Advanced Robotics), and VIBOT (master courses in VIsion & roBOTics). The structure of these masters is overviewed, the experience in designing and managing them is outlined and we point out the common effort for a global reach of these programmes and to build a transnational teaching architecture.

A concept of building a deployable mast using the Bennett linkage as the basic bay is proposed in this paper. The deployable mast is assembled by placing in series a number of modular bays constructed using the Bennett linkages. It has one degree of mobility. Geometrical analysis of the deployable mast has been conducted to determine the deployment length and cross section of the mast. The effects of the Bennett linkage parameters on the overall dimension of the mast are considered. The results show that the concept is valid and can be easily tailored to suit practical requirements.

Chu State repeating crossbow is a reconfigurable mechanism which was found in the tomb and dated back to the fourth century BC in ancient China. Since crossbows have diversified types and were widely used in ancient China after the Spring and Autumn Period (770-476 BC), Chu State repeating crossbow should have many designs in different eras and regions. The aim of this work is to synthesize mechanism structures of Chu State repeating crossbow. Based on the analyses of crossbows, the structural characteristics and design constraints of this device are concluded. Then, according to the concepts of generalization and specialization subject to the concluded design constraints, seven feasible structures of mechanism that meet the technological standards of the subject’s time period are reconstructed.

This paper investigates the duality of the five Platonic polyhedrons via the ray and axis coordinates of Line geometry. Then, based on the five Platonic polyhedrons, regular deployable polyhedral mechanisms are constructed by implanting the plane-symmetric eight-bar linkages into the edges, faces and vertices of the polyhedrons. Due to the duality of the five regular Platonic polyhedrons, it is revealed in this paper that the dual regular deployable polyhedral mechanisms constructed based on the dual Platonic polyhedrons are isomorphic and the isomorphism of the dual regular deployable polyhedral mechanisms is then for the first time presented via topology graphs and their corresponding adjacency matrices.

Deployable structures are widely used in a variety of space spacecrafts and planetary detectors. Under the size and cost limitations of space transportation system, deployable structure usually requires large contraction ratio and high reliability, therefore, development of deployable structures faces a series of theoretical and technical challenges. Space inflatable structure is a key area in space mechanism’s research. Compared to mechanically deployable structures, space inflatable structures have several unique advantages such as much lighter weight, higher packaging efficiency, lower life-cycle costs, simpler design with fewer parts, and higher deployment reliability. Inflatable structures with its irreplaceable advantages had attracted a lot of attentions during the past decades. This paper presents of a brief review of inflatable deployment space structures with stresses on their recent development and applications.

In this paper, a novel form of general line-symmetric Bricard linkage (GLSBL) that can be deployed onto arbitrary non-equilateral triangular profile and can be folded onto a bundle compact form with all the six links being parallel and contact to each other is presented. The mobility and detailed kinematic of the mechanism is studied. Using the novel GLSBL, a tripod mechanism using two similar deployable special form Bricard linkages as its bases connecting to three limbs is proposed. The tripod mechanism can be deployed onto triangular prism profile and can also be folded onto a bundle compact form so that it can be used as the basic building modules for the construction of large deployable trussed surface structures. Using this module, the deployable structure that can be deployed onto a spherical surface is presented.

A color-flipping ball can be considered as a kind of spatial mechanism. In this paper, the geometric characteristics and combined patterns of the color-flipping ball are presented. The equivalent schematics of the color-flipping ball both in its initial state and its flip state are illustrated. The relationships between the rotational angle and the scaling triangle are analyzed. From the scaling range equation, the velocity and acceleration of the motion are analyzed, and the corresponding kinematic curves are obtained using Matlab. The combined analysis of the basic element extracted from this mechanism is conducted. At last based on the result, an example is presented to show the application of the mechanism.

This paper investigates the foldability and the forward kinematics of the 3US parallel mechanisms. Based on the opportune arrangements of the Hooke joints axes, two foldable configurations with anticlockwise folding and clockwise deploying motion are presented. The forward kinematics of two configurations are analyzed which lead to the position expressions of the platform center and the orientation of the platform. The displacement expressions of two configurations are further compared. Moreover, the foldable configurations with clockwise folding and anticlockwise deploying motion are indicated to derive by mirroring the revolution axes of the Hooke joints associated with the base in each limb.

This paper proposes a reconfigurable lift mechanism which is composed of many planar revolute jointed linkages. Theoretically all of these linkages could be compacted to one line and then be further folded to a bundle. When working, the bundle first spreads out to a line and then connects two ends of the line to form a triangular closed loop so that the loop could ultimately deploy to act as a lift mechanism. Therefore, this kind of reconfigurable lift mechanism is portable and will be particularly used in some situations. The reconfigurable unit is first synthesized from the mobility requirement and the release of rigid joint constraint of the strengthened triangular frame is discussed to prove the possibility of completely folding after utilization for the whole mechanism. Prototype test shows that this kind of reconfigurable mechanism has very good stiffness and strength while keeping the portable characteristics.

The clearance appears in crankshaft pin and connecting rod bushing by manufacturing tolerance or wear of components is the most important factor that influences the dynamic performance and reliability of reciprocating pumps. In this paper, a parametric dynamic model of the crank-connecting rod mechanism of reciprocating pumps considering the crankshaft–bushing clearance is proposed based on the multibody dynamics theory. By simulation, the dynamic response of the mechanism with and without clearance is obtained and discussed. It is observed that the free flight motion between the pin and bushing occurs followed by the impact and rebound phenomenon when the mechanism moves from discharging period into sucking period. The simulation result of the joint force can be used for the strength and stiffness checking of the crankshaft.

Variable impedance actuators guarantee control performance for robots and robotic peripherals that are inherently safe to humans in their environment especially in cooperative tasks involving human-robot interaction. This paper presents a concept of variable impedance actuator using a combination of fluid and gas to realize the adaptation of the impedance. For this actuator, the ranges of variation of the impedance are studied with different initial conditions and positions of the piston in the actuator; The dynamic response characteristic is analyzed in presence of a variable external load. A method of control of the actuator is proposed and the performance shown while performing a testing cycle.

In order to overcome the shortcomings of existing cutting methods, H-beam cutting system was developed. This system which based on three-dimensional Pro/E model is three-cutting-torch H-beam robot cutting machine, it can realize the position control and the motion control of some auxiliary operations. This paper mainly describes system’s architecture, control method and key technologies used in this system. VBAPI, one of the redeveloping methods, is used in the model-driven technology and method of minimum delay-time is used in the path planning. The experiment results in practice show that: This system has well operability and applicability and can significantly improve the efficiency and quality of H-beam cutting.

Introducing the history of automatic cartoner from seventies in our country; Introducing the typical box-taking mechanism of automatic cartoner. Analyzing the principle and advantages of mechanisms and proposing the future development trend of automatic cartoning machine. There is a small gap between our country and foreign country in high-level automatic cartoning machine, some machines have achieved the synchronization with the world’s latest technology, but there are still gaps with foreign advanced level in the whole aspects of automatic cartoning machine.

Conventionally, industrial robots manipulate their end effector in a pre defined workspace. Structures are made rigid to cater the pay load requirements. Navigation of these arm inspired robots in cluttered environment pose a challenging task, hence the focus on the continuum robots becomes a cynosure. This precisely defines the requirement of a redundant manipulator where in the controllable degrees of freedom is more than the total degree of freedom in the work space. Present work is focused on design of one such manipulator that can function in a hassle milieu. This serial manipulator briefly named as multilink spatial hyper redundant robot comprises of sixteen links and fifteen joints. With each joint providing a prescribed degree of freedom a thirty degree of freedom is realized on the system. The degree of freedom of the system is precisely controlled using ropes which are driven by a rotary actuator. Kinematic approach to the configuration is proposed. A prototype of this robot was developed for analyzing the functionality and for future study.