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4 pages, 182 KiB

Open AccessEditorial

Robotics and Vibration Mechanics

by Alessandro Gasparetto, Lorenzo Scalera and Ilaria Palomba

Appl. Sci. 2022, 12(19), 9478; https://doi.org/10.3390/app12199478 - 21 Sep 2022

Viewed by 1420

Abstract

Robotics and vibration mechanics are among the main research areas in mechanical engineering [...] Full article

(This article belongs to the Special Issue Robotics and Vibration Mechanics)

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14 pages, 4348 KiB

Open AccessArticle

Torque Reduction of a Reconfigurable Spherical Parallel Mechanism Based on Craniotomy Experimental Data

by Terence Essomba, Juan Sandoval, Med Amine Laribi, Chieh-Tsai Wu, Cyril Breque, Saïd Zeghloul and Jean-pierre Richer

Appl. Sci. 2021, 11(14), 6534; https://doi.org/10.3390/app11146534 - 16 Jul 2021

Cited by 4 | Viewed by 2421

Abstract

This paper deals with a robotic manipulator dedicated to craniotomy with a remote center of motion based on a Spherical Parallel Manipulator (SPM) architecture. The SPM is proposed to handle the drilling tool through the requested craniotomy Degrees of Freedom (DoF) with two [...] Read more.

This paper deals with a robotic manipulator dedicated to craniotomy with a remote center of motion based on a Spherical Parallel Manipulator (SPM) architecture. The SPM is proposed to handle the drilling tool through the requested craniotomy Degrees of Freedom (DoF) with two rotations. The proposed architecture allows one degree of redundancy according to the total DoF. Thus, a first contribution of this work focuses on the experimental analysis of craniotomy surgery tasks. Secondly, its behavior is improved, taking advantage of the redundancy of the SPM using the spinning motion as a reconfiguration variable. The spinning angle modulation allows the reconfigurable manipulator to minimize its motor torques. A series of motion capture and force experimentations is performed for the analysis of the kinematic and force interaction characterizing Burr hole craniotomy procedures. Experimentations were carried out by a neurosurgeon on a human cadaver, ensuring highly realistic conditions. Full article

(This article belongs to the Special Issue Robotics and Vibration Mechanics)

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27 pages, 10885 KiB

Open AccessArticle

The Theoretical Study of an Interconnected Suspension System for a Formula Student Car

by Andrei-Cristian Pridie and Csaba Antonya

Appl. Sci. 2021, 11(12), 5507; https://doi.org/10.3390/app11125507 - 14 Jun 2021

Cited by 6 | Viewed by 4888

Abstract

When it comes to racing applications, the primary engineering goal is to increase the performance envelope of the vehicle for a given set of tires. To achieve this goal, it is necessary to maximize the normal loads on the wheels while at the [...] Read more.

When it comes to racing applications, the primary engineering goal is to increase the performance envelope of the vehicle for a given set of tires. To achieve this goal, it is necessary to maximize the normal loads on the wheels while at the same time minimizing the tire load variation. The purpose of this paper is to present a mathematical model for a Formula Student car in order to study if performance gains are achieved by replacing the traditional passive suspension with a hydraulically interconnected suspension system. To have a complete picture of the advantages and disadvantages of each system, two vibrating models with 7 degrees of freedom were created in order to simulate the motion response of a Formula Student car to realistic excitations. Two particular interpretations of the results were chosen as important performance indicators. The first one is given by the pitch stability of the chassis relative to the road, which can be linked with a decrease in downforce load variation. The second one is the ability of the wheel to follow the road profile as closely as possible, which can be directly correlated with the amount of mechanical grip of the vehicle. The simulation results indicate that the hydraulically interconnected suspension system offers better results for both proposed cases but at the expense of the roll stability of the vehicle. Full article

(This article belongs to the Special Issue Robotics and Vibration Mechanics)

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20 pages, 5185 KiB

Open AccessFeature PaperArticle

Vibration-Based Locomotion of an Amphibious Robot

by Silvio Cocuzza, Alberto Doria and Murat Reis

Appl. Sci. 2021, 11(5), 2212; https://doi.org/10.3390/app11052212 - 3 Mar 2021

Cited by 13 | Viewed by 3390

Abstract

In this research, an innovative robot is presented that can move both on land and water thanks to a vibration-based locomotion mechanism. The robot consists of a U-shaped beam made of spring steel, two low-density feet that allow it to stand on the [...] Read more.

In this research, an innovative robot is presented that can move both on land and water thanks to a vibration-based locomotion mechanism. The robot consists of a U-shaped beam made of spring steel, two low-density feet that allow it to stand on the water surface without sinking, and a micro-DC motor with eccentric mass, which excites vibrations. The robot exhibits stable terrestrial and aquatic locomotion based on the synchronization between body vibrations and the centrifugal force due to the eccentric mass. On the one hand, in aquatic locomotion, the robot advances thanks to floating oscillations and the asymmetric shape of the floating feet. On the other hand, the terrestrial locomotion, which has already been demonstrated for a similar robot, exploits the modes of vibration of the elastic beam. In this study, the effect of different excitation frequencies on the locomotion speed in water is examined by means of experimental tests and a numerical model. A good agreement between experimental and numerical results is found. The maximum locomotion speed takes place when the floating modes of vibration are excited. Full article

(This article belongs to the Special Issue Robotics and Vibration Mechanics)

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14 pages, 554 KiB

Open AccessArticle

Nonlinear Control of Multibody Flexible Mechanisms: A Model-Free Approach

by Paolo Boscariol, Lorenzo Scalera and Alessandro Gasparetto

Appl. Sci. 2021, 11(3), 1082; https://doi.org/10.3390/app11031082 - 25 Jan 2021

Cited by 15 | Viewed by 1948

Abstract

In this paper a novel nonlinear controller for position and vibration control of flexible-link mechanisms is introduced. The proposed control strategy is model-free and does not require the measurement of the elastic deformation of the mechanism, since the control relies only on the [...] Read more.

In this paper a novel nonlinear controller for position and vibration control of flexible-link mechanisms is introduced. The proposed control strategy is model-free and does not require the measurement of the elastic deformation of the mechanism, since the control relies only on the knowledge of the angular position of the actuator and on its time derivative, which can be measured simply with a quadrature encoder. The conditions for the closed-loop stability are evaluated using Lyapunov theory. The performance of the proposed technique is evaluated on a four-bar flexible-link mechanism. Superior vibration damping and more accurate trajectory tracking is obtained in comparison with a PD controller and a fractional order controller, which relies on the same set of measurement as the proposed nonlinear controller. Full article

(This article belongs to the Special Issue Robotics and Vibration Mechanics)

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22 pages, 2262 KiB

Open AccessArticle

Effect of End-Effector Compliance on Collisions in Robotic Teleoperation

by Domenico Tommasino, Giulio Cipriani, Alberto Doria and Giulio Rosati

Appl. Sci. 2020, 10(24), 9077; https://doi.org/10.3390/app10249077 - 18 Dec 2020

Cited by 7 | Viewed by 2302

Abstract

In robotic teleoperation, hard impacts between a tool and the manipulated object may impair the success of a task. In order to develop a robotic system that is able to minimize the final velocity of an object after impact, a comprehensive approach is [...] Read more.

In robotic teleoperation, hard impacts between a tool and the manipulated object may impair the success of a task. In order to develop a robotic system that is able to minimize the final velocity of an object after impact, a comprehensive approach is adopted in this work, and the effect on the impact of the parameters of the tool and of the robot is studied. Mass, contact stiffness and damping, robot compliance and control and tool compliance are taken into account. A mathematical model including the tool and the robot moving along the approach direction shows that, in most conditions, robot compliance is not enough to mitigate the impact. A mechanical decoupling between the inertia of the tool and the inertia of the robot is needed. An elastic system based on a bi-stable mechanism is developed and its validity is shown by means of numerical simulations. Full article

(This article belongs to the Special Issue Robotics and Vibration Mechanics)

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24 pages, 10087 KiB

Open AccessArticle

Influence of the Approach Direction on the Repeatability of an Industrial Robot

by Michal Vocetka, Róbert Huňady, Martin Hagara, Zdenko Bobovský, Tomáš Kot and Václav Krys

Appl. Sci. 2020, 10(23), 8714; https://doi.org/10.3390/app10238714 - 5 Dec 2020

Cited by 19 | Viewed by 2904

Abstract

The article aims to prove the hypothesis, that an approach direction influences repeatability at target point of a trajectory. Unlike most researches that deal with absolute accuracy, this paper is focused on determining the achievable repeatability and the influence of the direction of [...] Read more.

The article aims to prove the hypothesis, that an approach direction influences repeatability at target point of a trajectory. Unlike most researches that deal with absolute accuracy, this paper is focused on determining the achievable repeatability and the influence of the direction of approach on it. To prove the hypothesis, several measurements are performed under different conditions, on industrial robot ABB IRB1200. To verify and confirm the result obtained from the resolvers located on the individual axes of the robot, the measurements are replicated using high-speed digital image correlation cameras. Using an external measuring device, the real repeatability of the robot endpoint is determined. The measurement proved the correctness of the hypothesis, i.e., the dependence of the approach direction on repeatability was proved. Furthermore, real deviations were measured and the extent of this influence on the robot repeatability was determined. Full article

(This article belongs to the Special Issue Robotics and Vibration Mechanics)

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26 pages, 7348 KiB

Open AccessArticle

Modeling, Simulation, and Vision-/MPC-Based Control of a PowerCube Serial Robot

by Jörg Fehr, Patrick Schmid, Georg Schneider and Peter Eberhard

Appl. Sci. 2020, 10(20), 7270; https://doi.org/10.3390/app10207270 - 17 Oct 2020

Cited by 7 | Viewed by 4788

Abstract

A model predictive control (MPC) scheme for a Schunk PowerCube robot is derived in a structured step-by-step procedure. Neweul-M² provides the necessary nonlinear model in symbolical and numerical form. To handle the heavy online computational burden concerning the derived nonlinear model, a [...] Read more.

A model predictive control (MPC) scheme for a Schunk PowerCube robot is derived in a structured step-by-step procedure. Neweul-M² provides the necessary nonlinear model in symbolical and numerical form. To handle the heavy online computational burden concerning the derived nonlinear model, a linear time-varying MPC scheme is developed based on linearizing the nonlinear system concerning the desired trajectory and the a priori known corresponding feed-forward controller. Camera-based systems allow sensing of the robot on the one hand and monitoring the environments on the other hand. Therefore, a vision-based MPC is realized to show the effects of vision-based control feedback on control performance. A semi-automatic trajectory planning is used to perform two meaningful experimental studies in which the advantages and restrictions of the proposed (vision-based) linear time-varying MPC scheme are pointed out. Everything is implemented on a slim, low-cost control system with a standard laptop PC. Full article

(This article belongs to the Special Issue Robotics and Vibration Mechanics)

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18 pages, 1326 KiB

Open AccessArticle

A Multicriteria Motion Planning Approach for Combining Smoothness and Speed in Collaborative Assembly Systems

by Rafael A. Rojas, Erich Wehrle and Renato Vidoni

Appl. Sci. 2020, 10(15), 5086; https://doi.org/10.3390/app10155086 - 24 Jul 2020

Cited by 22 | Viewed by 2779

Abstract

Human–robot interaction is an important aspect of Industry 4.0, and the extended use of robotics in industrial environments will not be possible without enabling them to safely interact with humans. This imposes relevant constraints in the qualitative characterization of the motions of robots [...] Read more.

Human–robot interaction is an important aspect of Industry 4.0, and the extended use of robotics in industrial environments will not be possible without enabling them to safely interact with humans. This imposes relevant constraints in the qualitative characterization of the motions of robots when sharing their workspace with humans. In this paper, we address the trade-off between two such constraints, namely the smoothness, which is related to the cognitive stress that a person undergoes when interacting with a robot, and the speed, which is related to normative safety requirements. Given an execution time, such an approach will allow us to plan safe trajectories without neglecting cognitive ergonomics and production efficiency aspects. We first present the methodology able to express the balance between these qualities in the form of a composite objective function. Thanks to the variational formalism, we identify the related set of optimal trajectories with respect to the given criterion and give a suitable parametrization to them. Then, we are able to formulate the safety requirements in terms of a reparametrization of the motion. Finally, numerical and experimental results are provided. This allows the identification of the preferable sets of the possible motions that satisfy the operator’s psychological well-being and the assembly process performance by complying with the safety requirements in terms of mechanical risk prevention. Full article

(This article belongs to the Special Issue Robotics and Vibration Mechanics)

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28 pages, 3897 KiB

Open AccessArticle

Multibody Dynamics of Nonsymmetric Planar 3PRR Parallel Manipulator with Fully Flexible Links

by Abdur Rosyid and Bashar El-Khasawneh

Appl. Sci. 2020, 10(14), 4816; https://doi.org/10.3390/app10144816 - 13 Jul 2020

Cited by 10 | Viewed by 2952

Abstract

This paper presents the implementation of the floating frame of reference formulation to model the flexible multibody dynamics of a nonsymmetric planar 3PRR parallel manipulator. All of the links, including the moving platform, of the manipulator under study are assumed flexible whereas the [...] Read more.

This paper presents the implementation of the floating frame of reference formulation to model the flexible multibody dynamics of a nonsymmetric planar 3PRR parallel manipulator. All of the links, including the moving platform, of the manipulator under study are assumed flexible whereas the joints are assumed rigid. Using the Euler-Bernoulli beam, the flexibility of the links is modeled by using the Rayleigh-Ritz and finite element approximations. In both approximations, fixed-free boundary conditions are applied to the elastic coordinates of the links. These boundary conditions enable the evaluation of the elastic displacement at a link tip coincident with the end-effector of the manipulator which is of interest in the high precision robotics application. Both the approximations were compared by applying two different types of loads to the manipulator. It is shown that the elastic displacements obtained by using both the approximations have an agreement with a slight difference in the magnitude. In addition, the sensitivity analysis shows that the rigidity of the manipulator is much affected by the in-plane depth of the manipulator links’ cross section. Full article

(This article belongs to the Special Issue Robotics and Vibration Mechanics)

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