Research

22 pages, 24007 KiB

Open AccessArticle

A Study on the Relationship between the Design of Aerotrain and Its Stability Based on a Three-Dimensional Dynamic Model

by Quang Huan Luong, Jeremy Jong, Yusuke Sugahara, Daisuke Matsuura and Yukio Takeda

Robotics 2020, 9(4), 96; https://doi.org/10.3390/robotics9040096 - 19 Nov 2020

Viewed by 3305

Abstract

A new generation electric high-speed train called Aerotrain has levitation wings and levitates under Wing-in-Ground (WIG) effect along a U-shaped guideway. The previous study found that lacking knowledge of the design makes the prototype unable to regain stability when losing control. In this [...] Read more.

A new generation electric high-speed train called Aerotrain has levitation wings and levitates under Wing-in-Ground (WIG) effect along a U-shaped guideway. The previous study found that lacking knowledge of the design makes the prototype unable to regain stability when losing control. In this paper, the nonlinear three-dimensional dynamic model of the Aerotrain based on the rigid body model has been developed to investigate the relationship between the vehicle body design and its stability. Based on the dynamic model, this paper considered an Aerotrain with a horizontal tail and a vertical tail. To evaluate the stability, the location and area of these tails were parameterized. The effects of these parameters on the longitudinal and directional stability have been investigated to show that: the horizontal tail gives its best performance if the tail area is a function of the tail location; the larger vertical tail area and (or) the farther vertical tail location will give better directional stability. As for the lateral stability, a dihedral front levitation wing design was investigated. This design did not show its effectiveness, therefore a control system is needed. The obtained results are useful for the optimization studies on Aerotrain design as well as developing experimental prototypes. Full article

(This article belongs to the Special Issue Theory and Practice on Robotics and Mechatronics)

► Show Figures

Figure 1

16 pages, 6845 KiB

Open AccessArticle

Parallel Architectures for Humanoid Robots

by Marco Ceccarelli, Matteo Russo and Cuauhtemoc Morales-Cruz

Robotics 2020, 9(4), 75; https://doi.org/10.3390/robotics9040075 - 23 Sep 2020

Cited by 20 | Viewed by 5936

Abstract

The structure of humanoid robots can be inspired to human anatomy and operation with open challenges in mechanical performance that can be achieved by using parallel kinematic mechanisms. Parallel mechanisms can be identified in human anatomy with operations that can be used for [...] Read more.

The structure of humanoid robots can be inspired to human anatomy and operation with open challenges in mechanical performance that can be achieved by using parallel kinematic mechanisms. Parallel mechanisms can be identified in human anatomy with operations that can be used for designing parallel mechanisms in the structure of humanoid robots. Design issues are outlined as requirements and performance for parallel mechanisms in humanoid structures. The example of LARMbot humanoid design is presented as from direct authors’ experience to show an example of the feasibility and efficiency of using parallel mechanisms in humanoid structures. This work is an extension of a paper presented at ISRM 2019 conference (International Symposium on Robotics and Mechatronics). Full article

(This article belongs to the Special Issue Theory and Practice on Robotics and Mechatronics)

► Show Figures

Figure 1

23 pages, 20950 KiB

Open AccessArticle

Displacement Analysis and Design of a (2–RRU)–URR Parallel Mechanism Performing 2R1T Output Motion for Thumb Rehabilitation

by Woo-hyeok Choi and Yukio Takeda

Robotics 2020, 9(3), 67; https://doi.org/10.3390/robotics9030067 - 28 Aug 2020

Cited by 3 | Viewed by 3964

Abstract

The thumb assists other fingers, and any damage in its functionality prevents the human hand from performing dexterous functions. In this paper, the kinematic design of the (2–RRU)–URR parallel mechanism as the application of the thumb rehabilitation device is proposed. This mechanism is [...] Read more.

The thumb assists other fingers, and any damage in its functionality prevents the human hand from performing dexterous functions. In this paper, the kinematic design of the (2–RRU)–URR parallel mechanism as the application of the thumb rehabilitation device is proposed. This mechanism is an over-constrained mechanism capable of achieving the required mobility with fewer joints. Three degrees of freedom exist—two rotational and one translational mobility—that are related to each thumb movement: adduction–abduction and flexion–extension. Considering the narrow space of the hand, actuators are designed to divide its placement into the surface of the palm. To avoid the collisions between the device and the hand, an offset was adopted. The displacement analysis problem is solved by dividing it into two parts: the planar motion generator (PMG) and orientation generator (OG), according to each functional motion, and the corresponding equations and procedures are presented. To clarify the basic characteristics of this mechanism, the reachable workspace of the PMG and rotational ability and sensitivity of the OG is demonstrated numerically. Because a large input torque difference is dangerous in the rehabilitation mechanism, the effective workspace is determined according to the magnitude of the input torque differences and compared with the measured thumb movements. Full article

(This article belongs to the Special Issue Theory and Practice on Robotics and Mechatronics)

► Show Figures

Figure 1

16 pages, 1448 KiB

Open AccessArticle

Forward Kinematic Model Resolution of a Special Spherical Parallel Manipulator: Comparison and Real-Time Validation

by Houssem Saafi, Med Amine Laribi and Said Zeghloul

Robotics 2020, 9(3), 62; https://doi.org/10.3390/robotics9030062 - 06 Aug 2020

Cited by 12 | Viewed by 4027

Abstract

This paper deals with a special architecture of Spherical Parallel Manipulators (SPMs) designed to be a haptic device for a medical tele-operation system. This architecture is obtained by replacing the kinematic of one leg of a classical 3-RRR SPM (R for revolute joint). [...] Read more.

This paper deals with a special architecture of Spherical Parallel Manipulators (SPMs) designed to be a haptic device for a medical tele-operation system. This architecture is obtained by replacing the kinematic of one leg of a classical 3-RRR SPM (R for revolute joint). The Forward Kinematic Model (FKM) is particularly addressed to allow the new master device to control the motion of a slave surgical robot. For this purpose, three methods are presented to solve the FKM and compared based on the criterion of time consuming and accuracy. For each method, namely, classic FKM, Improved method and serial FKM, the resolution procedure is detailed and the experimental validation is presented. After comparison, the serial approach involving the use of three sensors located on one leg of the master device is revealed as the most suitable. Experimental validation of the real-time motion control is successfully performed using the serial FKM. Full article

(This article belongs to the Special Issue Theory and Practice on Robotics and Mechatronics)

► Show Figures

Figure 1

14 pages, 12486 KiB

Open AccessArticle

Synthesis and Analysis of a Novel Linkage Mechanism with the Helical Motion of the End-Effector

by Alexey Fomin, Daniil Petelin and Andreas Jahr

Robotics 2020, 9(3), 53; https://doi.org/10.3390/robotics9030053 - 08 Jul 2020

Cited by 2 | Viewed by 6074

Abstract

The proposed study is focused on the development of a novel modification of the slider-crank mechanism, the kinematic scheme of which is organized by coupling planar and spatial (screw) kinematic chains. The structure of this mechanism provides the end-effector with a cyclic movement [...] Read more.

The proposed study is focused on the development of a novel modification of the slider-crank mechanism, the kinematic scheme of which is organized by coupling planar and spatial (screw) kinematic chains. The structure of this mechanism provides the end-effector with a cyclic movement along a helicoidal trajectory, while all other links have planar motions. A kinematic analysis of the synthesized mechanism is discussed in this study. The motion variables of the end-effector at different pitches in the screw joints are determined analytically and numerically. Based on the mechanism’s kinematic scheme, its assembling computer-aided design (CAD) model has been created, in accordance with which a physical prototype has been built. A functional performance of the prototype is studied by comparing the displacements of its end-effector with analogical displacements of the CAD model. The question of the technological application of the developed mechanism for spring winding and various objects’ screwing has been considered in this study. Full article

(This article belongs to the Special Issue Theory and Practice on Robotics and Mechatronics)

► Show Figures

Figure 1

12 pages, 868 KiB

Open AccessArticle

Real-Time Cable Force Calculation beyond the Wrench-Feasible Workspace

by Roland Boumann and Tobias Bruckmann

Robotics 2020, 9(2), 41; https://doi.org/10.3390/robotics9020041 - 27 May 2020

Cited by 6 | Viewed by 4172

Abstract

Under special circumstances, a cable-driven parallel robot (CDPR) may leave its wrench-feasible-workspace. Standard approaches for the computation of set-point cable forces are likely to fail in this case. The novel nearest corner method for calculating appropriate cable forces when the CDPR is outside [...] Read more.

Under special circumstances, a cable-driven parallel robot (CDPR) may leave its wrench-feasible-workspace. Standard approaches for the computation of set-point cable forces are likely to fail in this case. The novel nearest corner method for calculating appropriate cable forces when the CDPR is outside of its wrench-feasible-workspace was introduced in former work of the authors. The obtained cable force distributions aim at continuity and generate wrenches close to the desired values. The method employs geometrical operations in the cable force space and promises real-time usability because of its non-iterative structure. In a simplified simulation, a cable break scenario was used to carry out more detailed testing of the method regarding different parameters, a higher number of cables, and the numerical efficiency. A brief discussion about the continuity of the method when entering the wrench-feasible-workspace is presented. Full article

(This article belongs to the Special Issue Theory and Practice on Robotics and Mechatronics)

► Show Figures

Figure 1

26 pages, 6208 KiB

Open AccessArticle

A Note on Equivalent Linkages of Direct-Contact Mechanisms

by Wen-Tung Chang and Dung-Yan Yang

Robotics 2020, 9(2), 38; https://doi.org/10.3390/robotics9020038 - 20 May 2020

Cited by 3 | Viewed by 7048

Abstract

In this paper, the inequivalence of the direct-contact mechanisms and their equivalent four-bar linkages in jerk analysis is discussed. Kinematic analyses for three classical types of direct-contact mechanisms consisting of: (a) higher pairs with permanently invariant curvature centers, (b) higher pairs with suddenly [...] Read more.

In this paper, the inequivalence of the direct-contact mechanisms and their equivalent four-bar linkages in jerk analysis is discussed. Kinematic analyses for three classical types of direct-contact mechanisms consisting of: (a) higher pairs with permanently invariant curvature centers, (b) higher pairs with suddenly changed curvature, and (c) higher pairs with continuously varying curvature are performed, respectively, through their representative case studies. The analyzed results show that the equivalent four-bar linkage cannot give a correct value of jerk for most situations in the three case studies. Subsequently, the concept of “equivalent six-bar linkage” for direct-contact mechanisms is proposed in order to discuss the infeasibility of the equivalent four-bar linkage for jerk analysis. It is found that the suddenly changed or continuously varying curvature of the higher pairs is not considered in sudden or continuous link-length variations of the equivalent four-bar linkage, which further leads to inconsistency between the angular accelerations of the coupler and the contact normal, and finally results in the infeasibility of the equivalent four-bar linkage for jerk analysis of most direct-contact mechanisms. It is also found that the concept of equivalent six-bar linkage could be applied to evaluate more higher-order time derivatives for most direct-contact mechanisms. The presented case studies and discussion can give demonstrations for understanding the inequivalence of the direct-contact mechanisms and their equivalent four-bar linkages in the aspect of jerk analysis. Full article

(This article belongs to the Special Issue Theory and Practice on Robotics and Mechatronics)

► Show Figures

Figure 1

20 pages, 3124 KiB

Open AccessArticle

Developing Emotion-Aware Human–Robot Dialogues for Domain-Specific and Goal-Oriented Tasks

by Jhih-Yuan Huang, Wei-Po Lee, Chen-Chia Chen and Bu-Wei Dong

Robotics 2020, 9(2), 31; https://doi.org/10.3390/robotics9020031 - 07 May 2020

Cited by 8 | Viewed by 5060

Abstract

Developing dialogue services for robots has been promoted nowadays for providing natural human–robot interactions to enhance user experiences. In this study, we adopted a service-oriented framework to develop emotion-aware dialogues for service robots. Considering the importance of the contexts and contents of dialogues [...] Read more.

Developing dialogue services for robots has been promoted nowadays for providing natural human–robot interactions to enhance user experiences. In this study, we adopted a service-oriented framework to develop emotion-aware dialogues for service robots. Considering the importance of the contexts and contents of dialogues in delivering robot services, our framework employed deep learning methods to develop emotion classifiers and two types of dialogue models of dialogue services. In the first type of dialogue service, the robot works as a consultant, able to provide domain-specific knowledge to users. We trained different neural models for mapping questions and answering sentences, tracking the human emotion during the human–robot dialogue, and using the emotion information to decide the responses. In the second type of dialogue service, the robot continuously asks the user questions related to a task with a specific goal, tracks the user’s intention through the interactions and provides suggestions accordingly. A series of experiments and performance comparisons were conducted to evaluate the major components of the presented framework and the results showed the promise of our approach. Full article

(This article belongs to the Special Issue Theory and Practice on Robotics and Mechatronics)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Theory and Practice on Robotics and Mechatronics

Share This Special Issue

Special Issue Editors

Special Issue Information

Keywords

Published Papers (8 papers)

Research

Further Information

Guidelines

MDPI Initiatives

Follow MDPI