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Robotics, Volume 8, Issue 4 (December 2019)

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Open AccessArticle
“Hmm, Did You Hear What I Just Said?”: Development of a Re-Engagement System for Socially Interactive Robots
Robotics 2019, 8(4), 95; https://doi.org/10.3390/robotics8040095 - 09 Nov 2019
Abstract
Maintaining engagement is challenging in human–human interaction. When disengagements happen, people try to adapt their behavior with an expectation that engagement will be regained. In human–robot interaction, although socially interactive robots are engaging, people can easily drop engagement while interacting with robots. This [...] Read more.
Maintaining engagement is challenging in human–human interaction. When disengagements happen, people try to adapt their behavior with an expectation that engagement will be regained. In human–robot interaction, although socially interactive robots are engaging, people can easily drop engagement while interacting with robots. This paper proposes a multi-layer re-engagement system that applies different strategies through human-like verbal and non-verbal behaviors to regain user engagement, taking into account the user’s attention level and affective states. We conducted a usability test in a robot storytelling scenario to demonstrate technical operation of the system as well as to investigate how people react when interacting with a robot with re-engagement ability. Our usability test results reveal that the system has the potential to maintain a user’s engagement. Our selected users gave positive comments, through open-ended questions, to the robot with this ability. They also rated the robot with the re-engagement ability higher on several dimensions, i.e., animacy, likability, and perceived intelligence. Full article
(This article belongs to the Special Issue Autonomous Mobile Robots in Open World)
Open AccessArticle
Characterization and Lubrication of Tube-Guided Shape-Memory Alloy Actuators for Smart Textiles
Robotics 2019, 8(4), 94; https://doi.org/10.3390/robotics8040094 - 08 Nov 2019
Abstract
Smart textiles are flexible materials with interactive capabilities such as sensing, actuation, and computing, and in recent years have garnered considerable interest. Shape-memory alloy (SMA) wire is a well-suited for smart textiles due to its high strength, small size, and low mass. However, [...] Read more.
Smart textiles are flexible materials with interactive capabilities such as sensing, actuation, and computing, and in recent years have garnered considerable interest. Shape-memory alloy (SMA) wire is a well-suited for smart textiles due to its high strength, small size, and low mass. However, the contraction of SMA wire is low, limiting its usefulness. One solution to increasing net contraction is to use a long SMA wire and guide it inside a tube that is wound back and forth or coiled inside a smart textile. In this article, we characterize the performance of tube-guided SMA wire actuators. We investigate the effect of turn radius and number of loops, showing that the stroke of an SMA-based system can be improved by up to 69.81% using the tube-guided SMA wire actuator concept. Finally, we investigate how tube-guided SMA wire actuators can be lubricated to improve their performance. Coarse graphite powder and tungsten disulfide lubricant both delivered improvements in stroke compared with an unlubricated system. Full article
(This article belongs to the Special Issue Soft Machines: Integrating Sensing, Actuation and Computation)
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Open AccessCorrection
Correction: Bhagat, S.; et al. Deep Reinforcement Learning for Soft, Flexible Robots: Brief Review with Impending Challenges. Robotics 2019, 8, 4
Robotics 2019, 8(4), 93; https://doi.org/10.3390/robotics8040093 - 28 Oct 2019
Abstract
The authors wish to make the following corrections to this paper [1]: In Figure 1 of this paper [...] Full article
Open AccessArticle
Estimating Weight of Unknown Objects Using Active Thermography
Robotics 2019, 8(4), 92; https://doi.org/10.3390/robotics8040092 - 24 Oct 2019
Abstract
Successful manipulation of unknown objects requires an understanding of their physical properties. Infrared thermography has the potential to provide real-time, contactless material characterization for unknown objects. In this paper, we propose an approach that utilizes active thermography and custom multi-channel neural networks to [...] Read more.
Successful manipulation of unknown objects requires an understanding of their physical properties. Infrared thermography has the potential to provide real-time, contactless material characterization for unknown objects. In this paper, we propose an approach that utilizes active thermography and custom multi-channel neural networks to perform classification between samples and regression towards the density property. With the help of an off-the-shelf technology to estimate the volume of the object, the proposed approach is capable of estimating the weight of the unknown object. We show the efficacy of the infrared thermography approach to a set of ten commonly used materials to achieve a 99.1% R 2 -fit for predicted versus actual density values. The system can be used with tele-operated or autonomous robots to optimize grasping techniques for unknown objects without touching them. Full article
(This article belongs to the Section Robotics & Automation)
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Open AccessArticle
Control of the Sit-To-Stand Transfer of a Biped Robotic Device for Postural Rehabilitation
Robotics 2019, 8(4), 91; https://doi.org/10.3390/robotics8040091 - 23 Oct 2019
Abstract
This paper deals with the control of the sit-to-stand transfer of a biped robotic device (either an autonomous biped robot or a haptic assistive exoskeleton for postural rehabilitation). The control has been synthesized, instead of considering the physiology, analyzing the basic laws of [...] Read more.
This paper deals with the control of the sit-to-stand transfer of a biped robotic device (either an autonomous biped robot or a haptic assistive exoskeleton for postural rehabilitation). The control has been synthesized, instead of considering the physiology, analyzing the basic laws of dynamics. The transfer of a human from sitting on a chair to an erect posture is an interesting case study, because it treats biped balance in a two-phase dynamic setting, with an external force disturbance (the chair–pelvis contact) affecting the center of pressure under the feet. At the beginning, a body is sitting, with a fixed pelvis moving with the hips going toward the supporting feet and, contemporaneously, releasing the load from the chair with ankles and knee torques. Then, after lift-off, it reaches and maintains an erect posture. The paper objectives are threefold: identifying the major dynamical determinants of the exercise; sythesizing an automatic control for an autonomous device; proposing an innovative approach for the rehabilitation process with an exoskeleton. For this last objective, the paper extends the idea of the authors of a haptic exoskeleton for rehabilitation. It is driven to control the joints by electromiographical signals from the patient. The two spaces, cartesian (world) and joint, where, respectively, the automatic control and the patient operate, are considered and a technique to blend the two actions is proposed. The exoskeleton is programed to perform the exercise autonomously. Then, during the evolution of the phases of rehabilitation, we postulated to seamlessly move the control from one space (purely autonomous) to another (completely driven by the patient), choosing and keeping the postural tasks and joints (heaps, knees, or ankles) on which to apply each one of the two actions without interaction. Full article
(This article belongs to the Special Issue Advances in Italian Robotics)
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Open AccessArticle
Reliable Real-Time Ball Tracking for Robot Table Tennis
Robotics 2019, 8(4), 90; https://doi.org/10.3390/robotics8040090 - 22 Oct 2019
Abstract
Robot table tennis systems require a vision system that can track the ball position with low latency and high sampling rate. Altering the ball to simplify the tracking using, for instance, infrared coating changes the physics of the ball trajectory. As a result, [...] Read more.
Robot table tennis systems require a vision system that can track the ball position with low latency and high sampling rate. Altering the ball to simplify the tracking using, for instance, infrared coating changes the physics of the ball trajectory. As a result, table tennis systems use custom tracking systems to track the ball based on heuristic algorithms respecting the real-time constrains applied to RGB images captured with a set of cameras. However, these heuristic algorithms often report erroneous ball positions, and the table tennis policies typically need to incorporate additional heuristics to detect and possibly correct outliers. In this paper, we propose a vision system for object detection and tracking that focuses on reliability while providing real-time performance. Our assumption is that by using multiple cameras, we can find and discard the errors obtained in the object detection phase by checking for consistency with the positions reported by other cameras. We provide an open source implementation of the proposed tracking system to simplify future research in robot table tennis or related tracking applications with strong real-time requirements. We evaluate the proposed system thoroughly in simulation and in the real system, outperforming previous work. Furthermore, we show that the accuracy and robustness of the proposed system increases as more cameras are added. Finally, we evaluate the table tennis playing performance of an existing method in the real robot using the proposed vision system. We measure a slight increase in performance compared to a previous vision system even after removing all the heuristics previously present to filter out erroneous ball observations. Full article
(This article belongs to the Section Robotics & Automation)
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Open AccessArticle
Estimation and Closed-Loop Control of COG/ZMP in Biped Devices Blending CoP Measures and Kinematic Information
Robotics 2019, 8(4), 89; https://doi.org/10.3390/robotics8040089 - 22 Oct 2019
Abstract
The zero moment point ( Z M P ) and the linearized inverted pendulum model linking the Z M P to the center of gravity ( C O G ) have an important role in the control of the postural equilibrium (balance) of [...] Read more.
The zero moment point ( Z M P ) and the linearized inverted pendulum model linking the Z M P to the center of gravity ( C O G ) have an important role in the control of the postural equilibrium (balance) of biped robots and lower-limb exoskeletons. A solution for balance real time control, closing the loop from the joint actual values of the C O G and Z M P , has been proposed by Choi. However, this approach cannot be practically implemented: While the Z M P actual value is available from the center of pressure ( C o P ) measured under the feet soles, the C O G is not measurable, but it can only be indirectly assessed from the joint-angle measures, the knowledge of the kinematics, and the usually poorly known weight distribution of the links of the chain. Finally, the possible presence of unknown external disturbance forces and the nonlinear, complex nature of the kinematics perturb the simple relationship between the Z M P and C O G in the linearized model. The aim of this paper is to offer, starting from Choi’s model, a practical implementation of closed-loop balance control fusing C o P and joint-angle measures, eliminating possible inconsistencies. In order to achieve this result, we introduce a model of the linearized inverted pendulum for an extended estimation, not only of C O G and Z M P , but also of external disturbances. This model is then used, instead of Choi’s equations, for estimation and balance control, using H theory. As the C O G information is recovered from the joint-angle measures, the identification of a statistically equivalent serial chain ( S E S C ) linking the C O G to the joint angles is also discussed. Full article
(This article belongs to the Special Issue Advances in Italian Robotics)
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Open AccessReview
Questionnaires to Measure Acceptability of Social Robots: A Critical Review
Robotics 2019, 8(4), 88; https://doi.org/10.3390/robotics8040088 - 21 Oct 2019
Viewed by 76
Abstract
Understanding user perceptions is particularly important in developing social robots, which tend to have a high degree of interaction with humans. However, psychometric measures of robot acceptability have only recently started to become available. The present critical review outlines the psychometrically validated questionnaires [...] Read more.
Understanding user perceptions is particularly important in developing social robots, which tend to have a high degree of interaction with humans. However, psychometric measures of robot acceptability have only recently started to become available. The present critical review outlines the psychometrically validated questionnaires to measure social acceptability factors related to social robots. Using an iterative search strategy, articles were identified that reported on the development of such questionnaires as well as information about their psychometric properties. Six questionnaires were identified that provide researchers with options varying in length, content, and factor structure. Two of these questionnaires inquire about attitudes and anxieties related to robots, while two others capture a larger range of attitudes that extends to positive and neutral aspects as well. One of the questionnaires reviewed here was specific to inquiring about ethical issues related to the use of social robots for therapy with children with autism, and the last one was designed to provide an assessment of expectations of participants prior to interacting with a robot. Overall, the use of robot acceptability measures is still relatively new, and further psychometric work is necessary to provide confidence in the validity and reliability of these scales. Full article
Open AccessFeature PaperArticle
A Helical Microrobot with an Optimized Propeller-Shape for Propulsion in Viscoelastic Biological Media
Robotics 2019, 8(4), 87; https://doi.org/10.3390/robotics8040087 - 15 Oct 2019
Viewed by 123
Abstract
One major challenge for microrobots is to penetrate and effectively move through viscoelastic biological tissues. Most existing microrobots can only propel in viscous liquids. Recent advances demonstrate that sub-micron robots can actively penetrate nanoporous biological tissue, such as the vitreous of the eye. [...] Read more.
One major challenge for microrobots is to penetrate and effectively move through viscoelastic biological tissues. Most existing microrobots can only propel in viscous liquids. Recent advances demonstrate that sub-micron robots can actively penetrate nanoporous biological tissue, such as the vitreous of the eye. However, it is still difficult to propel a micron-sized device through dense biological tissue. Here, we report that a special twisted helical shape together with a high aspect ratio in cross-section permit a microrobot with a diameter of hundreds-of-micrometers to move through mouse liver tissue. The helical microrobot is driven by a rotating magnetic field and localized by ultrasound imaging inside the tissue. The twisted ribbon is made of molybdenum and a sharp tip is chemically etched to generate a higher pressure at the edge of the propeller to break the biopolymeric network of the dense tissue. Full article
(This article belongs to the Section Medical Robotics)
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Open AccessArticle
Dexterous Manipulation of Unknown Objects Using Virtual Contact Points
Robotics 2019, 8(4), 86; https://doi.org/10.3390/robotics8040086 - 12 Oct 2019
Viewed by 122
Abstract
The manipulation of unknown objects is a problem of special interest in robotics since it is not always possible to have exact models of the objects with which the robot interacts. This paper presents a simple strategy to manipulate unknown objects using a [...] Read more.
The manipulation of unknown objects is a problem of special interest in robotics since it is not always possible to have exact models of the objects with which the robot interacts. This paper presents a simple strategy to manipulate unknown objects using a robotic hand equipped with tactile sensors. The hand configurations that allow the rotation of an unknown object are computed using only tactile and kinematic information, obtained during the manipulation process and reasoning about the desired and real positions of the fingertips during the manipulation. This is done taking into account that the desired positions of the fingertips are not physically reachable since they are located in the interior of the manipulated object and therefore they are virtual positions with associated virtual contact points. The proposed approach was satisfactorily validated using three fingers of an anthropomorphic robotic hand (Allegro Hand), with the original fingertips replaced by tactile sensors (WTS-FT). In the experimental validation, several everyday objects with different shapes were successfully manipulated, rotating them without the need of knowing their shape or any other physical property. Full article
(This article belongs to the Special Issue Robotics in Spain 2019)
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Open AccessFeature PaperArticle
Tactile-Driven Grasp Stability and Slip Prediction
Robotics 2019, 8(4), 85; https://doi.org/10.3390/robotics8040085 - 26 Sep 2019
Viewed by 280
Abstract
One of the challenges in robotic grasping tasks is the problem of detecting whether a grip is stable or not. The lack of stability during a manipulation operation usually causes the slippage of the grasped object due to poor contact forces. Frequently, an [...] Read more.
One of the challenges in robotic grasping tasks is the problem of detecting whether a grip is stable or not. The lack of stability during a manipulation operation usually causes the slippage of the grasped object due to poor contact forces. Frequently, an unstable grip can be caused by an inadequate pose of the robotic hand or by insufficient contact pressure, or both. The use of tactile data is essential to check such conditions and, therefore, predict the stability of a grasp. In this work, we present and compare different methodologies based on deep learning in order to represent and process tactile data for both stability and slip prediction. Full article
(This article belongs to the Special Issue Robotics in Spain 2019)
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Open AccessArticle
Design and Preliminary Testing of a Continuum Assistive Robotic Manipulator
Robotics 2019, 8(4), 84; https://doi.org/10.3390/robotics8040084 - 26 Sep 2019
Viewed by 493
Abstract
Background: The application of continuum manipulators as assistive robots is discussed and tested through the use of Bendy ARM, a simple manually teleoperated tendon driven continuum manipulator prototype. Methods: Two rounds of user testing were performed to evaluate the potential of this arm [...] Read more.
Background: The application of continuum manipulators as assistive robots is discussed and tested through the use of Bendy ARM, a simple manually teleoperated tendon driven continuum manipulator prototype. Methods: Two rounds of user testing were performed to evaluate the potential of this arm to aid people living with disabilities in completing activities of daily living. Results: In the first round of user testing, 14 able-bodied subjects successfully completed the prescribed task (pick-and-place) using multiple control schemes after being given a brief introduction and one minute of practice with each scheme. In the second round of user testing, subjects ( n = 3 ) demonstrated between 29.5 and 48.9 percent improvement in completion time across twelve trials of a peg-in-hole task, and between 8.4 and 33.8 percent improvement across six trials of a task involving opening and closing a drawer. Conclusion: Based on these results, it is posited that continuum manipulators merit further consideration as a safer and more cost-effective alternative to existing commercially available assistive robotic manipulators. Full article
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Open AccessTutorial
System-Level Testing and Evaluation Plan for Field Robots: A Tutorial with Test Course Layouts
Robotics 2019, 8(4), 83; https://doi.org/10.3390/robotics8040083 - 22 Sep 2019
Viewed by 393
Abstract
Field robotics is a very important sub-field of robotic systems, focusing on systems which need to navigate in open, unpredictable terrain and perform non-repetitive missions while monitoring and reacting to their surroundings. General testing and validation standards for larger robotic systems, including field [...] Read more.
Field robotics is a very important sub-field of robotic systems, focusing on systems which need to navigate in open, unpredictable terrain and perform non-repetitive missions while monitoring and reacting to their surroundings. General testing and validation standards for larger robotic systems, including field robots, have not been developed yet due to a variety of factors including disagreement over terminology and functional/performance requirements. This tutorial presents a generalized, step-by-step system-level test plan for field robots under manual, semi-autonomous/tele-operated, and autonomous control schemes; this includes a discussion of the requirements and testing parameters, and a set of suggested safety, communications, and behavior evaluation test courses. The testing plan presented here is relevant to both commercial and academic research into field robotics, providing a standardized general testing procedure. Full article
(This article belongs to the Section Agricultural and Field Robotics)
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Open AccessFeature PaperArticle
Online Multi-Objective Model-Independent Adaptive Tracking Mechanism for Dynamical Systems
Robotics 2019, 8(4), 82; https://doi.org/10.3390/robotics8040082 - 22 Sep 2019
Viewed by 273
Abstract
The optimal tracking problem is addressed in the robotics literature by using a variety of robust and adaptive control approaches. However, these schemes are associated with implementation limitations such as applicability in uncertain dynamical environments with complete or partial model-based control structures, complexity [...] Read more.
The optimal tracking problem is addressed in the robotics literature by using a variety of robust and adaptive control approaches. However, these schemes are associated with implementation limitations such as applicability in uncertain dynamical environments with complete or partial model-based control structures, complexity and integrity in discrete-time environments, and scalability in complex coupled dynamical systems. An online adaptive learning mechanism is developed to tackle the above limitations and provide a generalized solution platform for a class of tracking control problems. This scheme minimizes the tracking errors and optimizes the overall dynamical behavior using simultaneous linear feedback control strategies. Reinforcement learning approaches based on value iteration processes are adopted to solve the underlying Bellman optimality equations. The resulting control strategies are updated in real time in an interactive manner without requiring any information about the dynamics of the underlying systems. Means of adaptive critics are employed to approximate the optimal solving value functions and the associated control strategies in real time. The proposed adaptive tracking mechanism is illustrated in simulation to control a flexible wing aircraft under uncertain aerodynamic learning environment. Full article
(This article belongs to the Section Robotics & Automation)
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