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Publications (126)
In design matters, mechanisms with deformable elements are a step behind those with rigid bars, particularly if dimensional synthesis is considered a fundamental part of mechanism design. For the purposes of this work, a hybrid rigid–flexible four-bar mechanism has been chosen, the input bar being a continuum tendon of constant curvature. The coupl...
Translational Parallel Manipulators proved to be effective mechanisms in different application fields, from industries to haptic devices. The introduction of intrinsic flexibility within these mechanisms looks promising at increasing the safety of robots that are adopted in collaborative work-spaces. This paper focuses on the analysis of different...
This paper proposes a general formulation intended for dimensional synthesis of kinematic chains based on the derivation of kinematic constraint equations in their matrix form and their subsequent assembly in a system of linear equations. In this way, the proposed formulation allows to calculate in a simple way the partial derivatives of the nodal...
A parallel continuum manipulator (PCM) is a mechanism of closed-loop morphology with flexible elements such that their deformation contributes to its mobility. Flexible hexapods are six-degrees-of-freedom (DoF) fully parallel continuum mechanisms already presented in the literature. Devices of reduced mobility, i.e., lower mobility than six DoF, ha...
For chapter 15 In the original version of the book, the following correction has been updated: In Chapter 15, one of the author’s names has been changed from “Edoardo Id” to “Edoardo Idà”. The book and the chapter have been updated with the change.
This paper presents a general formulation intended for path generation synthesis based on the derivation of kinematic constraint equations in their matrix form and their subsequent assembly in a system of linear equations. The procedure enables obtaining in a simple way the partial derivatives of the nodal coordinates of a mechanism with respect to...
One of the first rehabilitation exercises in a hemiplegic patient is the recovery of the trunk balance, as a previous stage for the gait training. In this paper, a solution to assist this task with a robotic device is proposed and discussed. It is based on a compliant parallel kinematics manipulator of 4 degrees of freedom, 3 rotations and a transl...
This paper presents the design and testing of two haptic devices, based on reconfigurable 2R joints: an active 2R spherical mechanism-based joint and a differential gear-based joint. Based on our previous works, in which the design and kinematic analysis of both reconfigurable joints were developed, the experimental setup and the various tasks inte...
Compliant mechanisms are widely used for instrumentation and measuring devices for their precision and high bandwidth. In this paper, the mechatronic model of a compliant 3PRS parallel manipulator is developed, integrating the inverse and direct kinematics, the inverse dynamic problem of the manipulator and the dynamics of the actuators and the con...
The objective of the present work is to improve a device for rehabilitating the trunk balance and motion of patients who have suffered a stroke. The device is based on a parallel continuum manipulator coupled to a standing frame, where a wearable jacket is actuated by four flexible limbs connected to rotary motors. It has been designed to perform b...
Hybrid rigid–flexible mechanisms are a type of compliant mechanism that combines rigid and flexible elements, being that their mobility is due to rigid-body joints and the relative flexibility of bendable rods. Two of the modeling methods of flexible rods are the Cosserat rod model and its simplification, the Kirchhoff rod model. Both of them prese...
The objective of the present work is to develop a device for training the trunk balance and motion during the early stage of rehabilitation of patients who have suffered a stroke. It is coupled to a standing frame and is based on a parallel continuum manipulator where a wearable jacket is moved by four flexible limbs actuated by rotary motors, achi...
Parallel Continuum Mechanisms are closed-loop mechanical systems formed by flexible rods connected to a rigid end-effector and actuated from the base attachments of such rods. It was shown in previous works that they have analogous kinematic features to rigid-link parallel mechanisms. Position analysis is a force equilibrium problem with a multipli...
In our previous study, we developed an extendable arm inspired by the origami spring composed of rigid components, which performs largely tilting configurations in a space. However, this extendable arm had a problem in its static performance under external load. It is related to the shape of and the mass distribution in the mechanism. This paper pr...
The consequence of the population aging in last decades has been an increase of age-related disorders, such as multiple sclerosis, Parkinson’s disease, spinal cord injury or central nervous diseases, causing a deficiency in mobility and thus affecting the quality of life of adults [1, 2].
Kinematics position problems in planar parallel continuum mechanisms, whose elements are elastic rods undergoing nonlinear large deformations, are ruled by a system of nonlinear differential equations. Under some conditions, those rods can be modelled as Kirchhoff rods whose equations can be solved using elliptic integrals. The resolution has to be...
One of the main advantages of parallel manipulators over serial manipulators is their capacity to achieve faster and more precise movements, which is why they are used in many industrial applications. A parallel manipulator is formed by two or more parallel sets of rigid elements connected in series, and the corresponding actuators. Nevertheless, a...
Parallel continuum mechanisms are closed, kinematic, chained compliant mechanisms that are mobile due to flexible and slender elements. Large deformations and the force-moment equilibrium require a more complex modeling of the kinematic analysis than in their rigid-link counterparts. Although real-time solutions to the position problem using numeri...
Parallel Continuum Mechanisms are manipulators whose end-effector is connected with several compliant legs. Continuum manipulators of such kind have been considered historically serial devices because most of them have a long slender form. Nevertheless, these architectures contain aspects resembling their rigid-link parallel analogs. In this paper,...
Parallel Continuum Manipulators are parallel mechanisms which movement is due to the deformation of some of their elements, usually flexible rods. Provided that rods are straight in their stress-free reference state and that the movement of the mechanism is within a plane, elliptic integral solution can be used in order to get the deformation of ea...
In this paper, the authors present the CIRUS robot. This automatic system uses a combination of pulse-echo and pitch and catch ultrasonic strategies for the inspection of the welded area of mooring chain links in an automatic way. The robot is divided in three parts: global positioning subsystem, local positioning subsystem and inspection subsystem...
It is important for the mechatronic design of robotic systems to rely on accurate models. To that end, system identification methods are a convenient tool to obtain the values of the unknown dynamic parameters which play a key role. In this paper, it is investigated the application of the principle of energy equivalence to easily obtain a suitable...
This paper presents the multi-objective optimization of a three-degree-of-freedom parallel manipulator. First, the geometry of the mechanism is described and its kinematic and static performance is characterized with closed-form expressions of workspace volume and force efficiency. These indices are used as objective functions of the optimization,...
Parallel manipulators, especially those with outputs as a translation and two rotations (1T2R), are being increasingly studied. The 3PRS mechanism is a very typical example of this category, but it has peculiar kinematic characteristics caused by parasitic motions and by low orientation capability. To overcome these problems, new mechanisms are bei...
Welding flaw detection is a key step in manufacturing many components. In offshore chains, every link is manufactured from a steel bar that is bent and the ends joined by flash butt welding. Ultrasonic inspection of the welded area is required for classification. Defects, if any, are parallel to the welded area, which do not favour detection by man...
In this paper, a parallel mechanism with 3-UPR architecture for a robotic leg application is analyzed for design purposes. The proposed morphology is characterized by the convergence of the three chains to a single point of the moving platform. First, the mechanism is described and its inverse and forward kinematic problems are solved analytically....
This paper deals with the design of a robotic device for limb exercising. The attached problem is outlined to identify the main limb exercising features as referring to upper limbs and cable driven robotic solutions. A novel design solution is proposed as consisting in a portable low-cost user-friendly cable driven manipulator. Numerical models and...
In the field of parallel kinematics few designs use highly deformable elements to obtain the end effector movement. Most compliant mechanisms rely on notches or shape changes to simulate a standard kinematic joint. In this work a kinematic model of a simple parallel continuum mechanism that combines a deformable element and cable is presented. The...
The objective of this work is to develop a manipulator of 5 degrees of freedom for micromilling. It consists of a XY stage under a 3PRS compliant parallel mechanism, obtaining the advantages of the compliant joints as are higher repetitiveness, smoother motion and a higher bandwidth, due to the high precision demanded from the process, under 0.1 μm...
Continuum Parallel Robots are mechanical devices with closed loops where kinematic pairs have been eliminated and motion is obtained by large deformations of certain elements. Most compliant mechanisms use notches in thick elements to produce the effect of kinematic pairs. A few are designed so that slender elements can deform and produce the desir...
Abstract In this paper, a procedure for the kinematic design of a 3-PRS compliant parallel manipulator of 3 degree of freedom is proposed. First, under the assumption of small displacements, the solid body kinematics of the 3-PRS has been studied, performing a comprehensive analysis of the inverse and forward kinematic problem, and calculating the...
In this work a mechatronic model was developed for a parallel Multi-Axial Simulation Table (MAST) mechanism. The dynamics of the mechanism was obtained using the principle of energy equivalence and Boltzmann–Hamel equations. In this way, the procedure to obtain the explicit dynamic equations is simplified and has the advantage of being systematic....
In this paper, the interaction between the dynamics of the routing process and the vibration behavior of the ARABA I lightweight machine is presented. Firstly, the dynamics of the routing is evaluated by the critical depth of cut of the lobes diagrams of the process. Secondly, the structural dynamics of the machine is analyzed by means of its exper...
In this paper, a design methodology intended for the so-called cuspidal parallel manipulators is presented. The methodology is valid for three-degree-of-freedom planar or spatial parallel manipulators. The paper explains step-by-step a process to take advantage of a parallel manipulator that owns the cuspidality property, and thus, it can perform n...
In this paper, authors show the results of performance simulation of a 3PRS lower-mobility parallel manipulator actuated by electronic devices. The simulation includes a mechatronic model of the actuators, the dynamic response of the mechanism found using the Boltzmann-Hamel equations, and a model of the control. The dynamics of the actuators is mo...
The present work deals with the development of a hybrid manipulator of 5 degrees of freedom for milling moulds for microlenses. The manipulator is based on a XY stage under a 3PRS compliant parallel mechanism. The mechanism takes advantage of the compliant joints to achieve higher repetitiveness, smoother motion and a higher bandwidth, due to the h...
Multi-level manipulators are those mechanisms in which two or more levels, that define the main chain of the manipulator, are joined in parallel to each other. Besides, each level is linked to the base in parallel by some limbs. Based on the idea of multi-level manipulators and using the concept of plain leg surfaces, the synthesis of partially dec...
Explicit Dynamic equations are needed for simulation and control in the field of Mechatronics. Several classical methods are available to get Dynamic equations. Regarding those methods that aim exclusively at the equations relating applied torques and motion generated, i.e. avoiding any calculus of joint wrenches, Analytical mechanics offers severa...
Reconfigurable parallel manipulators combine the properties of parallel manipulators with high flexibility. However, the workspace of parallel manipulators is, compared to serial manipulators, relatively small and hence the optimization of the useful workspace is an important design factor. Different efficient algorithms for calculating the workspa...
In this paper, a mechatronic model of a planar parallel manipulator is developed and experimentally validated. The model considers the dynamics of the actuators, as well as the PID control algorithm with position, velocity and current cascaded loops and their timing. As our main contributions, the dynamics of the manipulator have been solved using...
Flexure stages are widely used in the field of micro and nanopositioning because of their repeatability and precision, which is due to the lack of joints that induces uncertainty. In the present Twork, a XY flexure stage has been analyzed and redesigned to reduce the axis cross-coupling, which is due to a parasitic motion in the amplification stage...
Protein simulation remains as one of the most difficult task for biologists, physicists or engineers. The huge computational requirements of the protein models makes it difficult to obtain simulations of big conformational changes on protein structure. Side chain modelization is a critical step when obtaining the protein structure model. The time s...
Parallel manipulators, compared to serial manipulators, have some interesting properties, such as high stiffness, low inertia, high velocity, good accuracy and large payload capacity. Thus, parallel manipulators, especially the ones with one translation and two rotations as outputs (1T2R), are being increasingly studied. The 3PRS mechanism is a ver...
The aim of this work is to approach the difficulties students usually encounter when facing up to kinematic analysis of mechanisms. A deep understanding of the kinematic analysis is necessary to go a step further into design and synthesis of mechanisms. We can conclude from experience that supporting and complementing the theoretical lectures with...
Educational software for the kinematic analysis of planar and spatial mechanisms is presented in this article. This general-purpose kinematic software has been developed as a complement to Machine Theory lectures. The different modules integrated in the software compute and analyse various kinematic entities, which enable an advanced student to inv...
Solar trackers are devices that improve the efficiency of photovoltaic collectors increasing the area exposed to direct radiation of the sun. The main drawback of these kinds of devices is that they have to consume certain energy in order to move the collectors following the sun trajectory. This work presents the detailed design of a mechanism with...
The aim of the present work is to present a fast identification method to estimate the inertial and friction parameters of a rigid body dynamic model of an electromechanical actuator. These are the dominant effects that determine the dynamics of machines and although the inertia is easily predictable, the friction can only be accurately known perfo...
In this work, a comparative study of the energy needed to run a 3-degree of freedom (DOF) parallel manipulator (PKM) for two different configurations of the inputs and two different transformation matrices for a concrete trajectory is presented. The 3-PRS is a PKM of low mobility, i.e., it has less than 6-DOF and when the main motion takes place, u...
This paper is focused on the type synthesis of four degrees-of-freedom fully-parallel manipulators for Schonflies or SCARA motion. The approach chosen isbased on the Theory of Groups of Displacements, which provides a simple and intuitive tool to define any architecture of parallel manipulator that can perform a prescribed motion, even though eithe...
The instantaneous motion capability of the end-effector of a manipulator is readily described by the type of screwsystem spanned. Such systems are classified by finding their principal screws. The analytical determination of such a base has been researched in the past using different techniques. The contribution of this paper is that the procedure...
Max Kohl Company, in Chemnitz (Germany), was a manufacturer of educational mechanisms that were distributed all around the world. In the early twentieth century, the University of Salamanca (USAL) bought some of them for the Engineering School of B́ejar. Now, this collection of mechanisms is being restored by a group of professors of the Engineerin...
The aim of this paper is to describe a general methodology for enlarging the workspace within which a parallel manipulator can move in a controllable way. The basis for obtaining this consists in superimposing all the singularity-free regions associated with the various different robot working modes. These can be connected because such transitions...
Two of the main sources of position error in parallel manipulators are clearances at joints and elastic deformations of the links. The former are usually necessary in order to produce a smooth movement between the pin and the hub of a joint. The latter are unavoidable and they tend to be greater in manipulators designed for pick-and-place tasks due...
In this paper, we present the static and dynamic structural characterisation of a low-mobility parallel kinematic manipulator, involving analysis of its stiffness and vibrational dynamic behaviour. The study starts by building numerical models of the behaviour of the manipulator to be compared to experimental measurements from a prototype. For the...
Protein motion simulation is still a troublesome problem yet to be solved, especially due to its high computational requirements. The procedure presented in this paper makes use of the proteins’ real degrees of freedom (DOFs). The procedure makes no use of any intermediate energy minimization processes that may alter the motion path or result in ve...
The instantaneous motion capability of a link of a mechanism, specifically the end-effector of a manipulator, is readily described by the type of screw system spanned. Such systems are classified by finding their principal screws, i.e. a basis of the motion space. The analytical determination of such a base has been researched in the past using dif...
Solar tracking devices try to increase the area exposed to direct radiation of the sun. The main drawback of these kind of devices is the energy consumed when following the sun. This work presents the design of a mechanism able to accurately follow the sun motion minimizing the energy consumption during its operation. The objective is achieved by m...
The object of this article is to obtain in a systematic form all the families of parallel manipulators with 3 degrees of freedom considering solely fully parallel manipulators whose legs are structurally identical. The motion pattern of the end-effector that should be taken into account are: 3T, 2T1R, 1T2R and 3R, where T and R refer to the charact...
The aim of this paper is to describe a general and systematic methodology to make controllable transitions between different solutions of the direct kinematic problem (DKP) from the joint space. This work is focused on parallel manipulators and the goal is the usage of just the input variables domain. This way, such transitions can be made controll...
Purpose
The purpose of this paper is to present a step‐by‐step methodology for the design of parallel kinematic machines (PKMs), from the initial stages of the conceptual definition of a new machine to an optimum design fulfilling the complete set of design requirements.
Design/methodology/approach
The methodology includes consideration of the kin...
The accuracy of parallel manipulators is linked to their stiffness and this has been shown to be configuration dependent. Indeed, certain types of singular configurations are usually avoided because of the associated loss of stiffness. These undesirable singularities are direct singularities, in which actuators cannot balance external loads. By con...
This paper deals with the static characterisation of a parallel manipulator for routing processes. Since accuracy and surface finishing are critical in all machining processes, the performance of a parallel machine is analysed in this paper in terms of these parameters. Using a previously developed static analysis methodology, the stiffness of the...
In this paper, the analytic 3-R$\underline{\hbox{P}}$ R platform studied by Wenger and Chablat in 2009 will be analyzed regarding its cuspidality condition. Many investigations have paid great attention to the cuspidality phenomena that arise for some designs of the 3-R $\underline{\hbox{P}}$R parallel manipulator. Nevertheless, most of them focus...
In this paper, a study of the capabilities of a parallel manipulator with four degrees of freedom for machining application is presented. Specifically, routing tasks will be considered. To carry out this study, a process model that allows the dynamic behaviour of robot based on the phenomenon of chatter to be considered is used. The model takes int...
The interest in using mobile robots in education has increased over the last two decades, as it is a multidisciplinary exercise in which the student needs to apply different subjects related to robotics, control engineering, software engineering, and electronics. In this chapter, the design and development of a mobile robot focused on the assistanc...
This paper presents a new symmetric parallel Schonflies-motion generator. The design is an evolution of a previous robot with linear inputs. The complete kinematic analysis of the 4-degree-of-freedom (dof) parallel manipulator is presented. The degrees of freedom are obtained from the Group Theory, the direct and inverse position problems are solve...
Clearances at joints produce a loss of accuracy when positioning a mechanism. The end-effector pose error due to clearances depends on the mechanism configuration, the magnitude of the clearance itself and applied external wrenches. Sudden changes which occur in the actual posture of the mechanism owing to a change of contact mode at joints can be...
In mechanism design and in the particular case of the parallel manipulator, most optimization problems involve simultaneously optimizing more than one objective function. In this paper, a method to identify Pareto-optimal solutions for the design of low-mobility parallel manipulators is presented. A 4-degree-of-freedom symmetric parallel manipulato...
In the design of parallel manipulators, a major problem is their reduced operational workspace. This is mainly due to the existence of a complex singularity locus within the workspace. The singularity-free workspace therefore corresponds to only a fraction of the potential workspace, and dimensioning the manipulator is intended to optimize such sin...
Clearances at joints and deformability of links produce a loss of accuracy when positioning a mechanism. End-effector pose error depends on the mechanism configuration, the applied external wrenches, the nature and magnitude of clearances and the rigidity of the mechanical components. Clearance magnitudes and elastic deformations are much smaller t...
In this paper a general methodology for obtaining static stiffness maps in lower mobility parallel manipulators is proposed. The main objective is to define a set of guidelines, which allow the experimental work to be optimized and computational time to be reduced. First, a two-degree-of-freedom (DOF) mechanism will be used for methodology validati...
In this paper, the authors present a general methodology for computing the configuration space for three-degree-of-freedom parallel manipulators so that the relation between input and output variables can be easily assessed. Making use of an entity called the reduced configuration space, all solutions of the direct kinematic problem in parallel man...
When a parallel manipulator is intended to became a parallel kinematic machine, practical tools for the end user should be provided. In this paper some guidelines for the definition of the structural analysis procedure are proposed. These rules provide the designer with the information to define some useful and simple maps. These maps include the i...
Purpose
The purpose of this paper is to provide a general approach to compute, determine, and characterize the connectivity of the end‐effector of a robotic manipulator of arbitrary architecture, in any of the postures that it can reach.
Design/methodology/approach
The types of motion of this link, i.e. translational, screw motions, combinations t...
It is known that cuspidality phenomenon appears in some parallel manipulators, called cuspidal manipulators, being able to perform non-singular transitions
between different assembly modes. In this paper, the authors will present a methodology for obtaining the locus of cusp points
in the joint space, which will be applied to generic 3-RPR planar p...
This chapter has described and illustrated the strategy of obtaining enlarged workspaces connecting all working modes and keeping one of the parallel manipulator assembly modes. It has been used a procedure which is able to obtain all the singularity-free regions of the
The optimal design of a Low-Mobility Parallel Manipulator with Schönflies motion is the subject of this paper. First, a general
description of the manipulator is presented. Next, the discretized volume workspace is obtained making use of various circular
trajectories. Further, the volume variation with dimensional parameters is purposed for optimal...
In this paper, the authors will show a methodology for computing the configuration space with one constant input, basing on
the principles of the discretization methods. Taking chance of an entity called the reduced configuration space, the Direct
Kinematic Problem will be solved. Moreover, this entity allows the transition between different soluti...
The nonlinearity of the position equations of most parallel manipulators is one of the main disadvantages for the industrial application of this kind of mechanisms. In this paper, a systematic procedure for the type synthesis of lower mobility platforms, characterized by partially decoupled equation sets in their position problem, is presented. The...
It is known that there are parallel manipulators that can perform nonsingular transitions between different assembly modes. In particular, 3-degree-of-freedom (DOF) manipulators have received primary attention related to this phenomenon. In this paper, the conditions for the existence of special points in the projection of the direct-kinematic-prob...
The multiobjective optimal design of a four-degree-of-freedom symmetric parallel manipulator is the subject of this paper. The design has rotary actuators and generates SCARA motion. Kinematic functions are implemented and used in a multiobjective optimization. First, the manipulator description is made, and kinematic problems are solved. Then the...
A comprehensive dynamics analysis of a four degrees-of-freedom Schönflies parallel manipulator with parallelogram joints is presented. First, the manipulator kinematics and workspace analysis is performed. Then, the dynamics model is calculated using the Lagrangian formulation. The existence of parallelograms in the structure of the manipulator int...
The aim of this paper is to describe a general methodology to obtain the entire set of positions that a parallel manipulator can reach and the workspace regions where the robot is controllable. The workspace is computed using a hybrid analytical-discrete procedure. Next the singularity maps are traced by carrying out a kinematic analysis of the pos...
This paper looks at the “five-axis machines” for machining operations. These machines have five (or six at maximum) degrees of freedom (dof). The output motion must have at least three translational and two rotational dof. This output motion pattern can be obtained with different structural topologies: serial, parallel, hybrid and with serial and/o...
The multiobjective optimization of a four-degree-of-freedom symmetric parallel manipulator for Schönflies-motion generation is the subject of this paper. First, the inverse positioning problem is discussed, along with its velocity analysis. The workspace is then analyzed, thereby deriving a closed-form expression of the workspace volume, which depe...
In this paper, the authors will show a method to visualize the configuration space so that the relation between input and
output variables can be easily assessed. Making use of concepts such as the configuration space with constant input, it will
be possible to obtain all the Direct Kinematic Problem solutions in parallel manipulators, and analyse...