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We present design of a compact haptic device in which parallel mechanisms are utilized. The design realizes a large workspace
of orientational motion in a compact volume of the device. The device is a parallel-serial mechanism consisting of a modified
DELTA mechanism for translational motion and a spatial five-bar gimbal mechanism for orientational...
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... overview of the mechanism that we synthesize is shown in Figure 1. Architecture of the mechanism is shown in Figure 2, diagrammatically. ...
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... apply the stiffness model derived in the previous section to the modified DELTA mechanism in order to obtain a compliance matrix for the mechanism. A schematic diagram of this mechanism is shown in Figure 10. This mechanism is made of a base, bearings 0, three arms, bearings 1 and 2, three rod parts, bearings 3 and 4 and a traveling plate. ...
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... connection between the rod part and the arm and between the rod part and the traveling plate is through a pair of bearings as shown in Figure 11. The coefficients of elasticity in the axial and radial directions of this part are obtained as those for a bearing multiplied by two. ...
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... rod part is made of a planar parallel mechanism. This parallel mechanism consists of two parallel rods and the bearings 2 and 3 as shown in Figure 10 (see also Figures 3 and 4). We consider the two rods (Rod L and R) sepa- rately as shown in Figure 13 and calculate the compliance matrix of each rod, first, and then, the compliance matrix of the whole rod system. ...
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... parallel mechanism consists of two parallel rods and the bearings 2 and 3 as shown in Figure 10 (see also Figures 3 and 4). We consider the two rods (Rod L and R) sepa- rately as shown in Figure 13 and calculate the compliance matrix of each rod, first, and then, the compliance matrix of the whole rod system. According to Equation (4), the compliance matrices C eL and C eR for the rods L and R, respectively, shown in Figure 13, are given by Fig. 13. ...
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... consider the two rods (Rod L and R) sepa- rately as shown in Figure 13 and calculate the compliance matrix of each rod, first, and then, the compliance matrix of the whole rod system. According to Equation (4), the compliance matrices C eL and C eR for the rods L and R, respectively, shown in Figure 13, are given by Fig. 13. Modeling of the rod part and ...
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... (see also Figures 3 and 4). We consider the two rods (Rod L and R) sepa- rately as shown in Figure 13 and calculate the compliance matrix of each rod, first, and then, the compliance matrix of the whole rod system. According to Equation (4), the compliance matrices C eL and C eR for the rods L and R, respectively, shown in Figure 13, are given by Fig. 13. Modeling of the rod part ...
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... are undermobility and overmobility singularities [12]. Figure 14 shows the two types of singularity for the modified DELTA mechanism, diagrammatically on a plane. This figure suggests that the case where the base radius R is equal to or larger than the traveling plate radius r be more recommendable than the case where r > R because the former case does not have overmobility singularity in the workspace. ...
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... stiffness at the tip position (point U, see Figure 15) of the modified DELTA mechanism changes largely depending on the traveling plate position. Therefore, it is necessary to design the mechanism taking into consideration the tip stiffness at all points in the workspace. ...
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... changes of the compliance matrix for the tip (point U) under elastic deformation of all the elements together (arms, rods, motor axes, bearings 0, 1, 2, 3, and 4) are shown in Figure 16, where α is the angle between the traveling plate and the rod as has been shown in Figure 15. According to Figure 16, when α increases, each of the elements A, B, C, D and E of Equation (23) changes as follows: ...
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... changes of the compliance matrix for the tip (point U) under elastic deformation of all the elements together (arms, rods, motor axes, bearings 0, 1, 2, 3, and 4) are shown in Figure 16, where α is the angle between the traveling plate and the rod as has been shown in Figure 15. According to Figure 16, when α increases, each of the elements A, B, C, D and E of Equation (23) changes as follows: ...
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... changes of the compliance matrix for the tip (point U) under elastic deformation of all the elements together (arms, rods, motor axes, bearings 0, 1, 2, 3, and 4) are shown in Figure 16, where α is the angle between the traveling plate and the rod as has been shown in Figure 15. According to Figure 16, when α increases, each of the elements A, B, C, D and E of Equation (23) changes as follows: ...
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Citations
... Vulliez et al. [18] introduced Delthaptic, a 6-DOF haptic device based on two Delta robots and used for remote control. Uchiyama et al. [19] considered a similar 6-DOF device with one Delta robot; the device includes a 2-DOF five-bar gimbal mechanism and a 1-DOF rotational module. ...
... (20) and (21), we determine the "worst" end-effector twist or the "worst" external load wrench for each actuated joint and compute the corresponding values of the actuation speed or effort. The results can be compared to those obtained in Eq. (19) for a reference. ...
... Note that the actuation efforts in the first, second, and fourth drives become limited too. To explain such a behavior, consider Eq. (19). According to subsection 5.1, the i-th row j T i of transposed Jacobian matrix J T depends on angle φ y . ...
The research presents a kinematic analysis of a recently proposed Delta-type parallel robot with four degrees of freedom. In contrast to conventional Delta robots, the design of the proposed one allows its output link to rotate about a fixed axis. The article first considers the mobility analysis using screw theory and verifies the motion pattern of the output link. The inverse kinematics follows next and provides the relations used for a subsequent study on workspaces. All performed calculations form a basis for a singularity analysis, which constitutes the largest part of the work. To analyze singular configurations, the paper considers two approaches. The first approach operates with Jacobian matrices; the second one determines closeness to singularities by concerning actuation speeds and efforts. Both methods provide similar results, which confirms the validity of the applied techniques. Next, the paper presents an example of workspace analysis concerning constraints on the actuation efforts. The proposed method gives more accurate results compared with another conventional approach. Finally, the paper considers an example of trajectory planning between two singularity-free areas of the workspace. The developed techniques are used to move between these areas by adjusting the platform orientation.
... Therefore, a serial-parallel mixed type or an overactuated mechanism is typically used to address this problem. [9][10][11][12] Gosselin and Hamel 13 proposed a 3-RRR type spherical parallel mechanism with the advantage of a parallel structure for 3-DOF operation of a single rotation center. Due to the above-mentioned advantages of the mechanism, it was mainly developed as a non-exoskeleton-type desktop HMI. ...
In this study, a wrist human–machine interface with a single internal rotation center, which is efficient in terms of performance, size, and avoidance of kinematic interference, is proposed to realize the 3-degree-of-freedom rotational motion of the human wrist. For this purpose, an over-actuated coaxial spherical parallel mechanism is applied. The over-actuated mechanism is specially considered to improve the force feedback performance and to overcome the workspace limitations caused by the singularity. From a mechanical perspective, two links are coaxially connected to the base, and this rotation axis is designed to coincide with the wrist pronation–supination, which has the largest operating range in wrist motion. A prototype was fabricated and evaluated to validate the proposed mechanism. In addition, a usable design index was proposed for the design that prevents interference with the user in the workspace while minimizing the link inertia to optimize the device. This index is optimized with the general performance indices, that is, condition index and stiffness index. It was verified through simulation that the optimized wrist human–machine interface exhibited higher performance than other similar devices. In addition, range of motion is at least 104.3% than a daily living range of motion of the human wrist, guaranteeing all ranges of motion.
... Jacobian-based stiffness analysis methods have been developed both for serial manipulators [6, 7] and parallel manipulators [8][9][10][11][12]. These stiffness analysis methods have been used for the analysis of a wide range of parallel manipulators, such as machining robots [1, 13, 14], haptic devices [15, 16], and precision manipulators [17, 18]. Several researchers have recognized that loading can have a significant effect on a stiffness analysis [19, 20], which in turn can affect stability [21] and accuracy [22, 23]. ...
The Cartesian stiffness analysis of mechanisms and robotic manipulators is often performed using Jacobian-based stiffness analysis methods. In general it is necessary to consider the effect of loading, which introduces a Jacobian-derivative term. However, early examples of stiffness analyses of parallel manipulators in which the effect of loading was considered resulted in asymmetric stiffness matrices, which go against the definition of stiffness. By replicating those first analyses using an alternative formulation of the stiffness analysis, this paper finds that the earlier observed asymmetry can be explained as a modeling inconsistency. If that inconsistency is corrected, symmetric matrices are obtained, which supports the notion that the Jacobian-derivative term is an integral part of the stiffness analysis of parallel manipulators and mechanisms.
... Therefore, the haptic device has to satisfy several contrasting, not only in terms of human ergonomics and suitable effective (singularity-free) workspace but also in terms of low inertia, low friction, zero or near-zero backlash, high stiffness, stability, etc. For an example of step by step robotic haptic interface design see [Hayward, 1995] [Stocco et al., 2001] [Çavuşoglu et al., 2002b] [Uchiyama et al., 2007]. Moreover, for an overview of the used kinematic structures to realise haptic interfaces [Kim, 2010], for actuation side [Conti and Khatib, 2009], preferred sampling techniques [Shahabi et al., 2001] and for gravity compensation [Checcacci et al., 2002]. ...
This thesis investigates the major factors affecting teleoperation transparency in medical context.A wide state of art survey is carried out and a new point of view to classify haptic teleoperation literature is proposed in order to extract the decisive factors providing a transparent teleoperation.Furthermore, the roles of three aspects have been analysed.First, The role of the applied control architecture.To this aim, the performances of 3-channel teleoperation are analysed and guidelines to select a suitable control architecture for medical applications are proposed.The validation of these guidelines is illustrated through simulations.Second, the effects of motion disturbance in the manipulated environment on telepresence are analysed.Consequently, a new model of such moving environment is proposed and the applicability of the proposed model is shown through interaction port passivity investigation.Third analysed factor is the role of the interaction model accuracy on the transparency of interaction control based haptic teleoperation.This analysis is performed theoretically and experimentally by the design and implementation of Hunt-Crossly in AOB interaction control haptic teleoperation.The results are discussed and the future perspectives are proposed.
... In addition to these three main groups of methods for modeling the stiffness matrix, Uchiyama et al. [27] has derived an analytical model for the stiffness of a compact 6-DOF haptic device based on static elastic deformation of compliance elements. The total stiffness was calculated using the serial to parallel transformation, assuming the platform to be rigid, while modeling the elastic elements as beam elements and considering the radial stiffness of the bearings. ...
... Substituting Eq. (27) into Eq. (31) results in contact stiffness K sp of spherical joint ...
Efficient development and engineering of high performing interactive devices, such as haptic robots for surgical training benefits from model-based and simulation-driven design. The complexity of the design space and the multi-domain and multi-physics character of the behavior of such a product ask for a systematic methodology for creating and validating compact and computationally efficient simulation models to be used in the design process. Modeling the quasi-static stiffness is an important first step before optimizing the mechanical structure, engineering the control system, and performing hardware in the loop tests. The stiffness depends not only on the stiffness of the links, but also on the contact stiffness in each joint. A fine-granular Finite element method (FEM) model, which is the most straightforward approach, cannot, due to the model size and simulation complexity, efficiently be used to address such tasks. In this work, a new methodology for creating an analytical and compact model of the quasi-static stiffness of a haptic device is proposed, which considers the stiffness of actuation systems, flexible links and passive joints. For the modeling of passive joints, a hertzian contact model is introduced for both spherical and universal joints, and a simply supported beam model for universal joints. The validation process is presented as a systematic guideline to evaluate the stiffness parameters both using parametric FEM modeling and physical experiments. Preloading has been used to consider the clearances and possible assembling errors during manufacturing. A modified JP Merlet kinematic structure is used to exemplify the modeling and validation methodology.
... The third of them, the MSA incorporates the main ideas of FEA, but operates with rather large elements and flexible beams to describe the manipulator structure [13]–[16]. Uchiyama [19] has derived an analytical model for the stiffness of a compact 6-DoF Haptic device, which he utilizes the design of a stiff platform for translational motion. The elastic elements were modeled as beam elements and considering the radial stiffness of the bearings. ...
In this work a new methodology is proposed to model the static stiffness of a haptic device. This methodology can be used for other parallel, serial and hybrid manipulators. The stiffness model considers the stiffness of; actuation system; flexible links and passive joints. For the modeling of the passive joints a Hertzian contact model is introduced for both spherical and universal joints and a simply supported beam model for universal joints. For validation of the stiffness model a modified JP Merlet kinematic structure has been used as a test case. A parametric Ansys FEM model was developed for this test case and used to validate the resulting stiffness model. The findings in this paper can provide an additional index to use for multi-objective structural optimization to find an optimum compromise between a lightweight design and the stiffness performance for high precision motion within a larger workspace.
... Masaru Uchiyama et al. developed a new six degree-of-freedom (DoF) haptic interface. In their work [3], they used a novel spatial gimbal five bar mechanism for orientation and delta manipulator for positioning. ...
... In this table; λ is the degree of freedom of an unconstrained rigid body moving in the workspace of the mechanism, B is the number of mobile platforms, j p is the total number of joints on the mobile platforms, c L is the total number of legs of the manipulator, L is the number of independent loops, f T is the sum of mobility of all joints in the structural group. The DoF of the manipulator can be calculated using (1) as M= (1)(2)(3)6+15=3 with the properties provided in Table III. ...
... Forward kinematic solution is presented in(3). ...
Haptics technology has increased the precision and telepresence of the teleoperation and precision of the in-house robotic applications by force and surface information feedback. Force feedback is achieved through sending back the pressure and force information via a haptic device as the information is created or measured at the point of interest. In order to configure such a system, design, analysis and production processes of a haptic device, which is suitable for that specific application, becomes important. Today, haptic devices find use in assistive surgical robotics and most of the teleoperation systems. These devices are also extensively utilized in simulators to train medical and military personnel. The objective of this work is to design a haptic device with a new structure that has the potential to increase the precision of the robotic operation. Thus, literature is reviewed and possible robot manipulator designs are investigated to increase the precision in haptics applications. As a result of the investigations, conceptual designs are developed. Ultimately, final design is selected and produced after it is investigated in computer-aided-design (CAD) environment and its kinematic and structural analyses are carried out.
La téléopération est une composante essentielle de la robotique collaborative, sécurisant l'opérateur sur un poste de contrôle à distance. Dans ce contexte, la conception d'un dispositif haptique polyvalent, interface Homme/machine fidèle et robuste, constitue un challenge majeur.La thèse vise à développer un nouveau dispositif haptique à six degrés de liberté actifs, adapté à différentes applications. La construction du nouveau mécanisme, les choix technologiques de conception et la validation expérimentale du dispositif font l'objet de ce manuscrit.Les travaux s'articulent autour d'une stratégie systématique de conception mécatronique. Après un état de l'art des dispositifs polyvalents existants, les exigences fonctionnelles sont définies en accord avec les performances sensorimotrices humaines. Une phase de conception structurelle mène à l'élaboration d'une architecture originale, couplant deux robots Delta en parallèle à l'effecteur, une poignée sur liaison hélicoïdale. Ce dispositif innovant, le Delthaptic, permet d'atteindre un large espace de travail sans singularité, tout en conservant les avantages des mécanismes parallèles. La structure et l'actionnement du Delthaptic sont ensuite optimisés pour offrir une grande transparence à l'opérateur. Un prototype de l'interface haptique a été fabriqué et ses performances dynamiques ont été identifiées expérimentalement. Le Delthaptic est intégré au sein de la plateforme collaborative multirobot du laboratoire sur différentes applications, validant ainsi son bon fonctionnement et ses aptitudes comme dispositif haptique. Il peut piloter des robots industriels et collaboratifs, ou interagir avec un environnement virtuel en temps réel.
In this paper, a methodology for real time identification of various singularities for various workspace types of parallel robots is proposed. Python 3D simulation software has been developed to position the moving platform of the robot's CAD model through pre-defined rules in order to solve specific problems including singularity identification, obstacle avoidance, and path planning. The system is designed to identify the moving platform's best possible pose. Boolean logic is used to identify valid path trajectory through parametric sweep search method. Joint constraints are checked to validate the platforms' positions using the actuators' stroke length, their angles, and any possible collisions. Solutions for any desired pose, based on line collision and mesh model algorithms, are then found. The path, position and workspace data are verified against a kinematic model of the robot, developed in Solid works and Matlab software tools. The simulation system has been successfully tested using various n-dimensional interpolations based on the given case study.
