Editorial

3 pages, 158 KiB

Open AccessEditorial

by Marco Ceccarelli and Alessandro Gasparetto

Robotics 2019, 8(2), 30; https://doi.org/10.3390/robotics8020030 - 19 Apr 2019

Cited by 1 | Viewed by 5916

MEDER 2018, the IFToMM International Symposium on Mechanism Design for Robotics, was the fourth event of a series that was started in 2010 as a specific conference activity on mechanisms for robots [...] Full article

(This article belongs to the Special Issue Mechanism Design for Robotics)

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11 pages, 5656 KiB

Open AccessArticle

On the Design of a Safe Human-Friendly Teleoperated System for Doppler Sonography

by Juan Sebastián Sandoval Arévalo, Med Amine Laribi, Saïd Zeghloul and Marc Arsicault

Robotics 2019, 8(2), 29; https://doi.org/10.3390/robotics8020029 - 15 Apr 2019

Cited by 11 | Viewed by 6944

Abstract

Variable stiffness actuators are employed to improve the safety features of robots that share a common workspace with humans. In this paper, a study of a joint variable stiffness device developed by PPRIME Institute—called V2SOM— for implementation in the joints of a multi-DoF [...] Read more.

Variable stiffness actuators are employed to improve the safety features of robots that share a common workspace with humans. In this paper, a study of a joint variable stiffness device developed by PPRIME Institute—called V2SOM— for implementation in the joints of a multi-DoF robot is presented. A comparison of the interaction forces produced by a rigid body robot and a flexible robot using the V2SOM is provided through a dynamic simulator of a 7-DoF robot. As an example of potential applications, robot-assisted Doppler echography is proposed, which mainly focuses on guaranteeing patient safety when the robot holding the ultrasound probe comes into contact with the patient. For this purpose, an evaluation of both joint and Cartesian control approaches is provided. The simulation results allow us to corroborate the effectiveness of the V2SOM device to guarantee human safety when it is implemented in a multi-DoF robot. Full article

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16 pages, 1878 KiB

Open AccessArticle

A Toolbox for the Analysis of the Grasp Stability of Underactuated Fingers

by Giovanni Antonio Zappatore, Giulio Reina and Arcangelo Messina

Robotics 2019, 8(2), 26; https://doi.org/10.3390/robotics8020026 - 06 Apr 2019

Cited by 6 | Viewed by 5602

Abstract

In the design of humanoid robotic hands, it is important to evaluate the grasp stability, especially when the concept of underactuation is involved. The use of a number of degrees of actuation lower than the degrees of freedom has shown some advantages compared [...] Read more.

In the design of humanoid robotic hands, it is important to evaluate the grasp stability, especially when the concept of underactuation is involved. The use of a number of degrees of actuation lower than the degrees of freedom has shown some advantages compared to conventional solutions in terms of adaptivity, compactness, ease of control, and cost-effectiveness. However, limited attention has been devoted to the analysis of grasp performance. Some specific issues that need to be further investigated are, for example, the impact of the geometry of the fingers and the objects to be grasped and the value of the driving mechanical torques applied to the phalanges. This research proposes a software toolbox that is aimed to support a user towards an optimal design of underactuated fingers that satisfies stable and efficient grasp constraints. Full article

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15 pages, 7652 KiB

Open AccessEditor’s ChoiceArticle

V2SOM: A Novel Safety Mechanism Dedicated to a Cobot’s Rotary Joints

by Younsse Ayoubi, Med Amine Laribi, Said Zeghloul and Marc Arsicault

Robotics 2019, 8(1), 18; https://doi.org/10.3390/robotics8010018 - 06 Mar 2019

Cited by 9 | Viewed by 6303

Abstract

Unlike “classical” industrial robots, collaborative robots, known as cobots, implement a compliant behavior. Cobots ensure a safe force control in a physical interaction scenario within unknown environments. In this paper, we propose to make serial robots intrinsically compliant to guarantee safe physical human–robot [...] Read more.

Unlike “classical” industrial robots, collaborative robots, known as cobots, implement a compliant behavior. Cobots ensure a safe force control in a physical interaction scenario within unknown environments. In this paper, we propose to make serial robots intrinsically compliant to guarantee safe physical human–robot interaction (pHRI), via our novel designed device called V2SOM, which stands for Variable Stiffness Safety-Oriented Mechanism. As its name indicates, V2SOM aims at making physical human–robot interaction safe, thanks to its two basic functioning modes—high stiffness mode and low stiffness mode. The first mode is employed for normal operational routines. In contrast, the low stiffness mode is suitable for the safe absorption of any potential blunt shock with a human. The transition between the two modes is continuous to maintain a good control of the V2SOM-based cobot in the case of a fast collision. V2SOM presents a high inertia decoupling capacity which is a necessary condition for safe pHRI without compromising the robot’s dynamic performances. Two safety criteria of pHRI were considered for performance evaluations, namely, the impact force (ImpF) criterion and the head injury criterion (HIC) for, respectively, the external and internal damage evaluation during blunt shocks. Full article

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12 pages, 3107 KiB

Open AccessArticle

Cable Failure Operation Strategy for a Rehabilitation Cable-Driven Robot

by Giovanni Boschetti, Giuseppe Carbone and Chiara Passarini

Robotics 2019, 8(1), 17; https://doi.org/10.3390/robotics8010017 - 06 Mar 2019

Cited by 25 | Viewed by 6573

Abstract

Cable-Driven Parallel Robots (CDPR) have attracted significant research interest for applications ranging from cable-suspended camera applications to rehabilitation and home assistance devices. Most of the intended applications of CDPR involve direct interaction with humans where safety is a key issue. Accordingly, this paper [...] Read more.

Cable-Driven Parallel Robots (CDPR) have attracted significant research interest for applications ranging from cable-suspended camera applications to rehabilitation and home assistance devices. Most of the intended applications of CDPR involve direct interaction with humans where safety is a key issue. Accordingly, this paper addresses the safety of CDPRs in proposing a strategy to minimize the consequences of cable failures. The proposed strategy consists of detecting a cable failure and avoiding any consequent motion of the end-effector. This is obtained by generating a wrench that is opposite to the direction of the ongoing motion so that the end-effector can reach a safe position. A general formulation is outlined as well as a specific case study referring to the LAWEX (LARM Wire-driven EXercising device), which has been designed within the AGEWELL project for limb rehabilitation. Real-time calculation is carried out for identifying feasible cable tensions, which generate a motion that provides the desired braking force. Simulations are carried out to prove the feasibility and effectiveness of the strategy outlined here in cases of cable failure. Full article

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14 pages, 528 KiB

Open AccessEditor’s ChoiceArticle

Trajectory Design for Energy Savings in Redundant Robotic Cells

by Paolo Boscariol and Dario Richiedei

Robotics 2019, 8(1), 15; https://doi.org/10.3390/robotics8010015 - 20 Feb 2019

Cited by 15 | Viewed by 6398

Abstract

This work explores the possibility of exploiting kinematic redundancy as a tool to enhance the energetic performance of a robotic cell. The test case under consideration comprises a three-degree-of-freedom Selective Compliance Assembly Robot Arm (SCARA) robot and an additional linear unit that is [...] Read more.

This work explores the possibility of exploiting kinematic redundancy as a tool to enhance the energetic performance of a robotic cell. The test case under consideration comprises a three-degree-of-freedom Selective Compliance Assembly Robot Arm (SCARA) robot and an additional linear unit that is used to move the workpiece during a pick and place operation. The trajectory design is based on a spline interpolation of a sequence of via-points: The corresponding motion of the joints is used to evaluate, through the use of an inverse dynamic model, the actuators effort and the associated power consumption by the robot and by the linear unit. Numerical results confirm that the suggested method can improve both the execution time and the overall energetic efficiency of the cell. Full article

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17 pages, 2717 KiB

Open AccessArticle

Singularity Avoidance Control of a Non-Holonomic Mobile Manipulator for Intuitive Hand Guidance

by Matthias Weyrer, Mathias Brandstötter and Manfred Husty

Robotics 2019, 8(1), 14; https://doi.org/10.3390/robotics8010014 - 19 Feb 2019

Cited by 20 | Viewed by 9242

Abstract

Mobile manipulators are robot systems capable of combining logistics and manipulation tasks. They thus fulfill an important prerequisite for the integration into flexible manufacturing systems. Another essential feature required for modern production facilities is a user-friendly and intuitive human-machine interaction. In this work [...] Read more.

Mobile manipulators are robot systems capable of combining logistics and manipulation tasks. They thus fulfill an important prerequisite for the integration into flexible manufacturing systems. Another essential feature required for modern production facilities is a user-friendly and intuitive human-machine interaction. In this work the goal of code-less programming is addressed and an intuitive and safe approach to physically interact with such robot systems is derived. We present a natural approach for hand guiding a sensitive mobile manipulator in task space using a force torque sensor that is mount close to the end effector. The proposed control structure is capable of handling the kinematic redundancies of the system and avoid singular arm configurations by means of haptic feedback to the user. A detailed analysis of all possible singularities of the UR robot family is given and the functionality of the controller design is shown with laboratory experiments on our mobile manipulator. Full article

(This article belongs to the Special Issue Mechanism Design for Robotics)

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12 pages, 5889 KiB

Open AccessArticle

Use of McKibben Muscle in a Haptic Interface

by Walter Franco, Daniela Maffiodo, Carlo De Benedictis and Carlo Ferraresi

Robotics 2019, 8(1), 13; https://doi.org/10.3390/robotics8010013 - 18 Feb 2019

Cited by 9 | Viewed by 5352

Abstract

One of the most relevant issues in the development of a haptic interface is the choice of the actuators that are devoted to generating the reflection forces. This work has been particularly focused on the employment of the McKibben muscle to this aim. [...] Read more.

One of the most relevant issues in the development of a haptic interface is the choice of the actuators that are devoted to generating the reflection forces. This work has been particularly focused on the employment of the McKibben muscle to this aim. A prototype of one finger has been realized that is intended to be part of a haptic glove, and is based on an articulated mechanism driven by a McKibben muscle. A dynamic model of the finger has been created and validated; then, it has been used to define the control algorithm of the device. Experimental tests highlighted the static and dynamic effectiveness of the device and proved that a McKibben muscle can be appropriately used in such an application. Full article

(This article belongs to the Special Issue Mechanism Design for Robotics)

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18 pages, 10394 KiB

Open AccessArticle

Development of a Novel SMA-Driven Compliant Rotary Actuator Based on a Double Helical Structure

by Rasheed Kittinanthapanya, Yusuke Sugahara, Daisuke Matsuura and Yukio Takeda

Robotics 2019, 8(1), 12; https://doi.org/10.3390/robotics8010012 - 18 Feb 2019

Cited by 4 | Viewed by 6578

Abstract

This paper proposes a new shape memory alloy (SMA)-driven compliant rotary actuator that can perform both passive and self-actuated motions. This SMA actuator is suitable as a redundant actuation part in a parallel robot joint to assist with singularity postures where the robot [...] Read more.

This paper proposes a new shape memory alloy (SMA)-driven compliant rotary actuator that can perform both passive and self-actuated motions. This SMA actuator is suitable as a redundant actuation part in a parallel robot joint to assist with singularity postures where the robot might lose the ability to maintain the position and orientation of the end effector. The double helical compliant joint (DHCJ) was chosen as a candidate mechanism; it can act in soft compliance with linear characteristics and a wide range of motion. The experimental results validated that the proposed model can be used to simulate the DHCJ behavior. The use of this mechanism exhibits advantages such as one-axis rotational motion, linear behavior even for a compliant mechanism, stiffness in the other axes of motion, and compact size. SMA leaves (strips) were used as actuation parts, and a single SMA leaf was tested before combining with the double helical frame as an SMA actuator. The prototype was fabricated, and necessary parameters such as deflection angle, temperature, torque, and stress–strain were collected to define the model for a controller. This actuator is controlled by a feedforward controller and provides rotational motion for both forward and reverse sides with a maximal range of 40 degrees. Full article

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16 pages, 3645 KiB

Open AccessArticle

A Comparison of Robot Wrist Implementations for the iCub Humanoid ^†

by Divya Shah, Yuanqing Wu, Alessandro Scalzo, Giorgio Metta and Alberto Parmiggiani

Robotics 2019, 8(1), 11; https://doi.org/10.3390/robotics8010011 - 17 Feb 2019

Cited by 21 | Viewed by 18158

Abstract

This article provides a detailed comparative analysis of five orientational, two degrees of freedom (DOF) mechanisms whose envisioned application is the wrist of the iCub humanoid robot. Firstly, the current iCub mk.2 wrist implementation is presented, and the desired design objectives are proposed. [...] Read more.

This article provides a detailed comparative analysis of five orientational, two degrees of freedom (DOF) mechanisms whose envisioned application is the wrist of the iCub humanoid robot. Firstly, the current iCub mk.2 wrist implementation is presented, and the desired design objectives are proposed. Prominent architectures from literature such as the spherical five-bar linkage and spherical six-bar linkage, the OmniWrist-III and the Quaternion joint mechanisms are modeled and analyzed for the said application. Finally, a detailed comparison of their workspace features is presented. The Quaternion joint mechanism emerges as a promising candidate from this study. Full article

(This article belongs to the Special Issue Mechanism Design for Robotics)

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16 pages, 13321 KiB

Open AccessEditor’s ChoiceArticle

Non-Photorealistic Rendering Techniques for Artistic Robotic Painting

by Lorenzo Scalera, Stefano Seriani, Alessandro Gasparetto and Paolo Gallina

Robotics 2019, 8(1), 10; https://doi.org/10.3390/robotics8010010 - 11 Feb 2019

Cited by 25 | Viewed by 9722

Abstract

In this paper, we present non-photorealistic rendering techniques that are applied together with a painting robot to realize artworks with original styles. Our robotic painting system is called Busker Robot and it has been considered of interest in recent art fairs and international [...] Read more.

In this paper, we present non-photorealistic rendering techniques that are applied together with a painting robot to realize artworks with original styles. Our robotic painting system is called Busker Robot and it has been considered of interest in recent art fairs and international exhibitions. It consists of a six degree-of-freedom collaborative robot and a series of image processing and path planning algorithms. In particular, here, two different rendering techniques are presented and a description of the experimental set-up is carried out. Finally, the experimental results are discussed by analyzing the elements that can account for the aesthetic appreciation of the artworks. Full article

(This article belongs to the Special Issue Mechanism Design for Robotics)

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14 pages, 5553 KiB

Open AccessArticle

Design and Experiments of a Novel Humanoid Robot with Parallel Architectures

by Matteo Russo, Daniele Cafolla and Marco Ceccarelli

Robotics 2018, 7(4), 79; https://doi.org/10.3390/robotics7040079 - 04 Dec 2018

Cited by 26 | Viewed by 8045

Abstract

In this paper, the mechanical design of the LARMbot 2, a low-cost user-oriented humanoid robot was presented. LARMbot 2 is characterized by parallel architectures for both the torso and legs. The proposed design was presented with the kinematics of its main parts—legs, torso, [...] Read more.

In this paper, the mechanical design of the LARMbot 2, a low-cost user-oriented humanoid robot was presented. LARMbot 2 is characterized by parallel architectures for both the torso and legs. The proposed design was presented with the kinematics of its main parts—legs, torso, arms—and then compared to its previous version, which was characterized by a different leg mechanism, to highlight the advantages of the latest design. A prototype was then presented, with constructive details of its subsystems and its technical specifications. To characterize the performance of the proposed robot, experimental results were presented for both the walking and weight-lifting operations. Full article

(This article belongs to the Special Issue Mechanism Design for Robotics)

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19 pages, 2198 KiB

Open AccessArticle

Locomotion of a Cylindrical Rolling Robot with a Shape Changing Outer Surface

by Michael G. Puopolo, Jamey D. Jacob and Emilio Gabino

Robotics 2018, 7(3), 52; https://doi.org/10.3390/robotics7030052 - 10 Sep 2018

Cited by 4 | Viewed by 5508

Abstract

A cylindrical rolling robot is developed that generates roll torque by changing the shape of its flexible, elliptical outer surface whenever one of four elliptical axes rotates past an inclination called trigger angle. The robot is equipped with a sensing/control system by which [...] Read more.

A cylindrical rolling robot is developed that generates roll torque by changing the shape of its flexible, elliptical outer surface whenever one of four elliptical axes rotates past an inclination called trigger angle. The robot is equipped with a sensing/control system by which it measures angular position and angular velocity, and computes error with respect to a desired step angular velocity profile. When shape change is triggered, the newly assumed shape of the outer surface is determined according to the computed error. A series of trial rolls is conducted using various trigger angles, and energy consumed by the actuation motor per unit roll distance is measured. Results show that, for each of three desired velocity profiles investigated, there exists a range of trigger angles that results in relatively low energy consumption per unit roll distance, and when the robot operates within this optimal trigger angle range, it undergoes minimal actuation burdening and inadvertent braking, both of which are inherent to the mechanics of rolling robots that use shape change to generate roll torque. A mathematical model of motion is developed and applied in a simulation program that can be used to predict and further understand behavior of the robot. Full article

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17 pages, 4066 KiB

Open AccessArticle

Stability and Gait Planning of 3-UPU Hexapod Walking Robot

by Ruiqin Li, Hongwei Meng, Shaoping Bai, Yinyin Yao and Jianwei Zhang

Robotics 2018, 7(3), 48; https://doi.org/10.3390/robotics7030048 - 31 Aug 2018

Cited by 10 | Viewed by 7886

Abstract

The paper presents an innovative hexapod walking robot built with 3-UPU parallel mechanism. In the robot, the parallel mechanism is used as both an actuator to generate walking and also a connecting body to connect two groups of three legs, thus enabling the [...] Read more.

The paper presents an innovative hexapod walking robot built with 3-UPU parallel mechanism. In the robot, the parallel mechanism is used as both an actuator to generate walking and also a connecting body to connect two groups of three legs, thus enabling the robot to walk with simple gait by very few motors. In this paper, forward and inverse kinematics solutions are obtained. The workspace of the parallel mechanism is analyzed using limit boundary search method. The walking stability of the robot is analyzed, which yields the robot’s maximum step length. The gait planning of the hexapod walking robot is studied for walking on both flat and uneven terrains. The new robot, combining the advantages of parallel robot and walking robot, has a large carrying capacity, strong passing ability, flexible turning ability, and simple gait control for its deployment for uneven terrains. Full article

(This article belongs to the Special Issue Mechanism Design for Robotics)

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