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Robotics, Volume 9, Issue 3 (September 2020) – 26 articles

Cover Story (view full-size image): SVGS (Smartphone Video Guidance Sensor) is a vision-based embedded sensor, developed at NASA Marshall Space Flight Center using an Android-based smartphone, that enables proximity operations and formation flight in small satellite platforms. SVGS determines the relative position and orientation of a moving target relative to a coordinate system attached to the camera, by capturing an image of a set of illuminated points mounted on the target in a known geometric pattern. In the picture, SVGS is used as the real-time position and attitude sensor to control two RINGS (Resonant Inductive Near-field Generation Systems) ground units in a formation maneuver. Besides spacecraft guidance and control, SVGS can be used as a relative position and attitude sensor in a variety of robotic proximity operations such as docking, landing, and cooperative maneuvers. View this paper.
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Article
Research on Trajectory Tracking and Obstacle Avoidance of Nonholonomic Mobile Robots in a Dynamic Environment
Robotics 2020, 9(3), 74; https://doi.org/10.3390/robotics9030074 - 18 Sep 2020
Cited by 1 | Viewed by 1104
Abstract
This paper presents an obstacle-avoidance trajectory tracking method based on a nonlinear model prediction, with a dynamic environment considered in the trajectory tracking of nonholonomic mobile robots for obstacle avoidance. In this method, collision avoidance is embedded into the trajectory tracking control problem [...] Read more.
This paper presents an obstacle-avoidance trajectory tracking method based on a nonlinear model prediction, with a dynamic environment considered in the trajectory tracking of nonholonomic mobile robots for obstacle avoidance. In this method, collision avoidance is embedded into the trajectory tracking control problem as a nonlinear constraint of the position state, which changes with time to solve the obstacle-avoidance problem in dynamic environments. The CasADi toolkit was used in MATLAB to generate a real-time, efficient C++ code with inequality constraints to avoid collisions. Trajectory tracking and obstacle avoidance in dynamic and static environments are trialed using MATLAB and CasADi simulations, and the effectiveness of the proposed control algorithm is verified. Full article
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Article
Human Robot Hand Interaction with Plastic Deformation Control
Robotics 2020, 9(3), 73; https://doi.org/10.3390/robotics9030073 - 16 Sep 2020
Viewed by 1068
Abstract
In recent years, force control has become more important due to the physical interaction of robots with humans and applications of robots to complex environments. Impedance control is widely used in force control; however, it cannot reproduce the behavior of plastic deformation because [...] Read more.
In recent years, force control has become more important due to the physical interaction of robots with humans and applications of robots to complex environments. Impedance control is widely used in force control; however, it cannot reproduce the behavior of plastic deformation because it returns to the initial position when the force is removed, similar to elastic deformation. On the other hand, Senoo et al. have proposed plastic deformation control based on the Maxwell model. However, because plastic deformation control is model-based, it is subject to the modeling and parameter errors of the controlled system. A robot hand is relatively small and lightweight; because it uses a gearbox with a high reduction ratio for its joints, it is significantly affected by friction and tends to deviate strongly from the desired motion. Therefore, in this study, a method that is robust against modeling and parameter errors is proposed by feeding back the error from the desired trajectory with the inner position loop. Then, the effectiveness of the proposed method is shown through simulations and experiments using an actual robotic system. Full article
(This article belongs to the Section Intelligent Robots and Mechatronics)
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Article
Teachers’ Opinions towards Educational Robotics for Special Needs Students: An Exploratory Italian Study
Robotics 2020, 9(3), 72; https://doi.org/10.3390/robotics9030072 - 16 Sep 2020
Cited by 3 | Viewed by 1336
Abstract
Research reveals that robotics can be a valuable tool for school students with special needs (SNs). However, to our knowledge, empirical studies on teachers’ attitudes towards educational robotics for SNs students have been very limited and, in general, do not account for the [...] Read more.
Research reveals that robotics can be a valuable tool for school students with special needs (SNs). However, to our knowledge, empirical studies on teachers’ attitudes towards educational robotics for SNs students have been very limited and, in general, do not account for the great variability in the existent difficulties of school-aged children. Our aim is to fill this research gap. This post-test empirical study assessed Italian pre-service and in-service learning support teachers’ attitudes towards the application of Educational Robotics—ER with their students with SNs at the end of a 12-h training course. The results generally showed that most teachers perceived ER as a powerful tool for children with numerous SNs, particularly for Attention Deficit Hyperactivity Disorder—ADHD, Autism Spectrum Disorder—ASD, and Dyspraxia. Looking at the differences depending on the school level, kindergarten teachers perceived that ER is mostly helpful for ASD, ADHD, Down Syndrome—DS as well as with psychological or emotional distress or the needs of foreign students. For primary school teachers, ER was mostly helpful with ADHD, Dyspraxia and ASD. For both junior secondary school teachers and high school teachers, ER was mostly helpful with ASD, Dyspraxia, and ADHD. Full article
(This article belongs to the Special Issue Advances and Challenges in Educational Robotics)
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Communication
Computational Design Thinking and Physical Computing: Preliminary Observations of a Pilot Study
Robotics 2020, 9(3), 71; https://doi.org/10.3390/robotics9030071 - 10 Sep 2020
Viewed by 1192
Abstract
Today’s technological development inevitably defies educational approaches in terms of future demand for skills to be imparted. Among other skills, the capacity to operate and communicate effectively within multidisciplinary realms is duly considered as the fundamental one. Educational robotics (ER) and STEM do [...] Read more.
Today’s technological development inevitably defies educational approaches in terms of future demand for skills to be imparted. Among other skills, the capacity to operate and communicate effectively within multidisciplinary realms is duly considered as the fundamental one. Educational robotics (ER) and STEM do constitute a suitable framework for the development of these specific skills. Moreover, competences such as computational (CT) and design thinking (DT) have already been nominated as necessary to adapt to the future and relevant for innovation. The years of independent development and evidence of practical implementation justify the maturity of the related methodological approaches and emerging gradual shift towards their combination. In this regard, the actual work presents a pilot experience of the combined application of computational design thinking and educational robotics in the case of a 9-to-11-year-old target audience. The approach utilizes a novel platform developed under the project Coding4Girls combining design thinking and game-based learning and introduces physical computing through consecutive assembling and programming an IR-controlled robot-car. The core of the learning path consists in the development of primary programming skills and their gradual transfer into the physical realm. The method, as the study demonstrates, is capable of helping keep students both motivated and result-oriented throughout the duration of the course. Full article
(This article belongs to the Special Issue Advances and Challenges in Educational Robotics)
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Article
Proximity Operations and Three Degree-of-Freedom Maneuvers Using the Smartphone Video Guidance Sensor
Robotics 2020, 9(3), 70; https://doi.org/10.3390/robotics9030070 - 10 Sep 2020
Viewed by 1095
Abstract
This paper presents the first demonstration of NASA’s Smartphone Video Guidance Sensor (SVGS) as real-time position and attitude estimator for proximity and formation maneuvers. An optimal linear quadratic Gaussian controller was used, combining a linear quadratic regulator and a Kalman filter. The system [...] Read more.
This paper presents the first demonstration of NASA’s Smartphone Video Guidance Sensor (SVGS) as real-time position and attitude estimator for proximity and formation maneuvers. An optimal linear quadratic Gaussian controller was used, combining a linear quadratic regulator and a Kalman filter. The system was demonstrated controlling the 3-degree of freedom planar motion of the RINGS ground units (Resonant Inductive Near-field Generation Systems). A state-space model of the system’s 3-DOF motion dynamics was derived, and model parameters extracted using a system identification technique. The system’s motion control performance is experimentally demonstrated in both tracking and formation maneuvers. The results highlight the capabilities and performance of the Smartphone Video Guidance Sensor (SVGS) as a vision-based real-time position and attitude sensor for motion control, formation flight and proximity operations. A leader-follower formation maneuver approach is demonstrated, as well as position hold and path following. Full article
(This article belongs to the Section Aerospace Robotics and Autonomous Systems)
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Article
FloorVLoc: A Modular Approach to Floorplan Monocular Localization
Robotics 2020, 9(3), 69; https://doi.org/10.3390/robotics9030069 - 10 Sep 2020
Cited by 1 | Viewed by 1100
Abstract
Intelligent vehicles for search and rescue, whose mission is assisting emergency personnel by visually exploring an unfamiliar building, require accurate localization. With GPS not available, and approaches relying on new infrastructure installation, artificial landmarks, or pre-constructed dense 3D maps not feasible, the question [...] Read more.
Intelligent vehicles for search and rescue, whose mission is assisting emergency personnel by visually exploring an unfamiliar building, require accurate localization. With GPS not available, and approaches relying on new infrastructure installation, artificial landmarks, or pre-constructed dense 3D maps not feasible, the question is whether there is an approach which can combine ubiquitous prior map information with a monocular camera for accurate positioning. Enter FloorVLoc—Floorplan Vision Vehicle Localization. We provide a means to integrate a monocular camera with a floorplan in a unified and modular fashion so that any monocular visual Simultaneous Localization and Mapping (SLAM) system can be seamlessly incorporated for global positioning. Using a floorplan is especially beneficial since walls are geometrically stable, the memory footprint is low, and prior map information is kept at a minimum. Furthermore, our theoretical analysis of the visual features associated with the walls shows how drift is corrected. To see this approach in action, we developed two full global positioning systems based on the core methodology introduced, operating in both Monte Carlo Localization and linear optimization frameworks. Experimental evaluation of the systems in simulation and a challenging real-world environment demonstrates that FloorVLoc performs with an average error of 0.06 m across 80 m in real-time. Full article
(This article belongs to the Special Issue Feature Papers 2020)
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Article
Adaptive Kinematic Modelling for Multiobjective Control of a Redundant Surgical Robotic Tool
Robotics 2020, 9(3), 68; https://doi.org/10.3390/robotics9030068 - 31 Aug 2020
Cited by 3 | Viewed by 1674
Abstract
Accurate kinematic models are essential for effective control of surgical robots. For tendon driven robots, which are common for minimally invasive surgery, the high nonlinearities in the transmission make modelling complex. Machine learning techniques are a preferred approach to tackle this problem. However, [...] Read more.
Accurate kinematic models are essential for effective control of surgical robots. For tendon driven robots, which are common for minimally invasive surgery, the high nonlinearities in the transmission make modelling complex. Machine learning techniques are a preferred approach to tackle this problem. However, surgical environments are rarely structured, due to organs being very soft and deformable, and unpredictable, for instance, because of fluids in the system, wear and break of the tendons that lead to changes of the system’s behaviour. Therefore, the model needs to quickly adapt. In this work, we propose a method to learn the kinematic model of a redundant surgical robot and control it to perform surgical tasks both autonomously and in teleoperation. The approach employs Feedforward Artificial Neural Networks (ANN) for building the kinematic model of the robot offline, and an online adaptive strategy in order to allow the system to conform to the changing environment. To prove the capabilities of the method, a comparison with a simple feedback controller for autonomous tracking is carried out. Simulation results show that the proposed method is capable of achieving very small tracking errors, even when unpredicted changes in the system occur, such as broken joints. The method proved effective also in guaranteeing accurate tracking in teleoperation. Full article
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Article
Displacement Analysis and Design of a (2–RRU)–URR Parallel Mechanism Performing 2R1T Output Motion for Thumb Rehabilitation
Robotics 2020, 9(3), 67; https://doi.org/10.3390/robotics9030067 - 28 Aug 2020
Cited by 1 | Viewed by 1094
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)
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Article
Integrity Analysis for GPS-Based Navigation of UAVs in Urban Environment
Robotics 2020, 9(3), 66; https://doi.org/10.3390/robotics9030066 - 25 Aug 2020
Cited by 4 | Viewed by 1544
Abstract
The increasing use of Unmanned Aerial Vehicles (UAVs) in safety-critical missions in both civilian and military areas demands accurate and reliable navigation, where one of the key sources of navigation information is presented by Global Navigation Satellite Systems (GNSS). In challenging conditions, for [...] Read more.
The increasing use of Unmanned Aerial Vehicles (UAVs) in safety-critical missions in both civilian and military areas demands accurate and reliable navigation, where one of the key sources of navigation information is presented by Global Navigation Satellite Systems (GNSS). In challenging conditions, for example, in urban areas, the accuracy of GNSS-based navigation may degrade significantly due to user-satellite geometry and obscuration issues without being noticed by the user. Therefore, considering the essentially dynamic rate of change in this type of environment, integrity monitoring is of critical importance for understanding the level of trust we have in positioning and timing data. In this paper, the dilution of precision (DOP) coefficients under nominal and challenging conditions were investigated for the purpose of integrity monitoring in urban environments. By analyzing positioning information in a simulated urban environment using a software-based GNSS receiver, the integrity monitoring approach based on joint consideration of GNSS observables and environmental parameters has been proposed. It was shown that DOP coefficients, when considered together with a number of visible satellites and cut-off elevations specific to the urban environment carry valuable integrity information that is difficult to get using existing integrity monitoring approaches. This has allowed generating indirect integrity measures based on cut-off elevation and satellite visibility that can be used for UAV path planning and guidance in urban environments. Full article
(This article belongs to the Special Issue Navigation and Control of UAVs)
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Article
Workspace and Stiffness Analysis of 3D Printing Cable-Driven Parallel Robot with a Retractable Beam-Type End-Effector
Robotics 2020, 9(3), 65; https://doi.org/10.3390/robotics9030065 - 24 Aug 2020
Cited by 2 | Viewed by 1525
Abstract
3D printing is a widely used technology that has been recently applied in construction to reduce construction time significantly. A large 3D printer often uses a traditional Cartesian robot with inherent problems, such as position errors and printing nozzle vibrations, due to the [...] Read more.
3D printing is a widely used technology that has been recently applied in construction to reduce construction time significantly. A large 3D printer often uses a traditional Cartesian robot with inherent problems, such as position errors and printing nozzle vibrations, due to the long, heavy horizontal beam carrying it and a large amount of power required to actuate the heavy beam. A cable-driven parallel robot (CDPR) can be a good alternative system to reduce the vibrations and necessary power because the robot’s lightweight cables can manipulate the printing nozzle. However, a large 3D printing CDPR should be carefully designed to maximize the workspace and avoid cable interference. It also needs to be stiff enough to reject disturbances from the environment properly. A CDPR with a retractable beam-type end-effector with cables through the guide pulleys in a single plane is suggested for avoiding cable interference while maximizing the workspace. The effects of using the retractable end-effector on the workspace were analyzed relative to the cable connection points’ location changes. Static stiffness analysis was conducted to examine the natural frequencies, and the geometric parameters of the end-effector were adjusted to improve the lowest natural frequencies. Simulation results show that a retractable beam-type end-effector can effectively expand the wrench-feasible workspace. Full article
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Article
Classifying Intelligence in Machines: A Taxonomy of Intelligent Control
Robotics 2020, 9(3), 64; https://doi.org/10.3390/robotics9030064 - 21 Aug 2020
Viewed by 1435
Abstract
The quest to create machines that can solve problems as humans do leads us to intelligent control. This field encompasses control systems that can adapt to changes and learn to improve their actions—traits typically associated with human intelligence. In this work we seek [...] Read more.
The quest to create machines that can solve problems as humans do leads us to intelligent control. This field encompasses control systems that can adapt to changes and learn to improve their actions—traits typically associated with human intelligence. In this work we seek to determine how intelligent these classes of control systems are by quantifying their level of adaptability and learning. First we describe the stages of development towards intelligent control and present a definition based on literature. Based on the key elements of this definition, we propose a novel taxonomy of intelligent control methods, which assesses the extent to which they handle uncertainties in three areas: the environment, the controller, and the goals. This taxonomy is applicable to a variety of robotic and other autonomous systems, which we demonstrate through several examples of intelligent control methods and their classifications. Looking at the spread of classifications based on this taxonomy can help researchers identify where control systems can be made more intelligent. Full article
(This article belongs to the Section Industrial Robots & Automation)
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Article
Deep Learning-Based Object Classification and Position Estimation Pipeline for Potential Use in Robotized Pick-and-Place Operations
Robotics 2020, 9(3), 63; https://doi.org/10.3390/robotics9030063 - 18 Aug 2020
Cited by 1 | Viewed by 1467
Abstract
Accurate object classification and position estimation is a crucial part of executing autonomous pick-and-place operations by a robot and can be realized using RGB-D sensors becoming increasingly available for use in industrial applications. In this paper, we present a novel unified framework for [...] Read more.
Accurate object classification and position estimation is a crucial part of executing autonomous pick-and-place operations by a robot and can be realized using RGB-D sensors becoming increasingly available for use in industrial applications. In this paper, we present a novel unified framework for object detection and classification using a combination of point cloud processing and deep learning techniques. The proposed model uses two streams that recognize objects on RGB and depth data separately and combines the two in later stages to classify objects. Experimental evaluation of the proposed model including classification accuracy compared with previous works demonstrates its effectiveness and efficiency, making the model suitable for real-time applications. In particular, the experiments performed on the Washington RGB-D object dataset show that the proposed framework has 97.5% and 95% fewer parameters compared to the previous state-of-the-art multimodel neural networks Fus-CNN, CNN Features and VGG3D, respectively, with the cost of approximately 5% drop in classification accuracy. Moreover, the inference of the proposed framework takes 66.11%, 32.65%, and 28.77% less time on GPU and 86.91%, 51.12%, and 50.15% less time on CPU in comparison to VGG3D, Fus-CNN, and CNN Features. The potential applicability of the developed object classification and position estimation framework was then demonstrated on an experimental robot-manipulation setup realizing a simplified object pick-and-place scenario. In approximately 95% of test trials, the system was able to accurately position the robot over the detected objects of interest in an automatic mode, ensuring stable cyclic execution with no time delays. Full article
(This article belongs to the Special Issue Robotics and AI)
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Article
Forward Kinematic Model Resolution of a Special Spherical Parallel Manipulator: Comparison and Real-Time Validation
Robotics 2020, 9(3), 62; https://doi.org/10.3390/robotics9030062 - 06 Aug 2020
Cited by 1 | Viewed by 1420
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)
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Article
Globally Optimal Inverse Kinematics Method for a Redundant Robot Manipulator with Linear and Nonlinear Constraints
Robotics 2020, 9(3), 61; https://doi.org/10.3390/robotics9030061 - 31 Jul 2020
Cited by 6 | Viewed by 1821
Abstract
This paper presents a novel inverse kinematics global method for a redundant robot manipulator performing a tracking maneuver. The proposed method, based on the choice of appropriate initial joint trajectories that satisfy the kinematic constraints to be used as inputs for a multi-start [...] Read more.
This paper presents a novel inverse kinematics global method for a redundant robot manipulator performing a tracking maneuver. The proposed method, based on the choice of appropriate initial joint trajectories that satisfy the kinematic constraints to be used as inputs for a multi-start optimization algorithm, allows for the optimization of different integral cost functions, such as kinetic energy and joint torques norm, and can provide solutions with a variety of constraints, both linear and nonlinear. Furthermore, it is suitable for multi-objective optimization, and it is able to find multiple optima with minimal input from the user, and to solve cyclic trajectories. Problems with a high number of parameters have been addressed providing a sequential version of the method based on successive stages of interpolation. The results of simulations with a three-Degrees-of-Freedom (DOF) redundant manipulator have been compared with a solution available in the literature based on the calculus of variations, thus leading to the validation of the method. Moreover, the effectiveness of the presented method has been shown when used to solve problems with constraints on joint displacement, velocity, torque, and power. Full article
(This article belongs to the Special Issue Advances in Italian Robotics II)
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Article
A Novel 3-URU Architecture with Actuators on the Base: Kinematics and Singularity Analysis
Robotics 2020, 9(3), 60; https://doi.org/10.3390/robotics9030060 - 31 Jul 2020
Cited by 1 | Viewed by 1545
Abstract
Translational parallel manipulators (TPMs) with DELTA-like architectures are the most known and affirmed ones, even though many other TPM architectures have been proposed and studied in the literature. In a recent patent application, this author has presented a TPM with three equal limbs [...] Read more.
Translational parallel manipulators (TPMs) with DELTA-like architectures are the most known and affirmed ones, even though many other TPM architectures have been proposed and studied in the literature. In a recent patent application, this author has presented a TPM with three equal limbs of Universal-Revolute-Universal (URU) type, with only one actuated joint per limb, which has overall size and characteristics similar to DELTA robots. The presented translational 3-URU architecture is different from other 3-URUs, proposed in the literature, since it has the actuators on the frame (base) even though the actuated joints are not on the base, and it features a particular geometry. Choosing the geometry and the actuated joints highly affects 3-URU’s behavior. Moreover, putting the actuators on the base allows a substantial reduction of the mobile masses, thus promising good dynamic performances, and makes the remaining part of the limb a simple chain constituted by only passive R-pairs. The paper addresses the kinematics and the singularity analysis of this novel TPM and proves the effectiveness of the new design choices. The results presented here form the technical basis for the above-mentioned patent application. Full article
(This article belongs to the Special Issue Kinematics and Robot Design III, KaRD2020)
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Article
Adaptive Interval Type-2 Fuzzy Logic Control of a Three Degree-of-Freedom Helicopter
Robotics 2020, 9(3), 59; https://doi.org/10.3390/robotics9030059 - 30 Jul 2020
Viewed by 1563
Abstract
This paper combines interval type-2 fuzzy logic with adaptive control theory for the control of a three degree-of-freedom (DOF) helicopter. This strategy yields robustness to various kinds of uncertainties and guaranteed stability of the closed-loop control system. Thus, precise trajectory tracking is maintained [...] Read more.
This paper combines interval type-2 fuzzy logic with adaptive control theory for the control of a three degree-of-freedom (DOF) helicopter. This strategy yields robustness to various kinds of uncertainties and guaranteed stability of the closed-loop control system. Thus, precise trajectory tracking is maintained under various operational conditions with the presence of various types of uncertainties. Unlike other controllers, the proposed controller approximates the helicopter’s inverse dynamic model and assumes no a priori knowledge of the helicopter’s dynamics or parameters. The proposed controller is applied to a 3-DOF helicopter model and compared against three other controllers, i.e., PID control, adaptive control, and adaptive sliding-mode control. Numerical results show its high performance and robustness under the presence of uncertainties. To better assess the performance of the control system, two quantitative tracking performance metrics are introduced, i.e., the integral of the tracking errors and the integral of the control signals. Comparative numerical results reveal the superiority of the proposed method by achieving the highest tracking accuracy with the lowest control effort. Full article
(This article belongs to the Special Issue Robotics: Intelligent Control Theory)
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Article
Robotic Detection and Grasp of Maize and Sorghum: Stem Measurement with Contact
Robotics 2020, 9(3), 58; https://doi.org/10.3390/robotics9030058 - 28 Jul 2020
Cited by 1 | Viewed by 2055
Abstract
Frequent measurements of the plant phenotypes make it possible to monitor plant status during the growing season. Stem diameter is an important proxy for overall plant biomass and health. However, the manual measurement of stem diameter in plants is time consuming, error prone, [...] Read more.
Frequent measurements of the plant phenotypes make it possible to monitor plant status during the growing season. Stem diameter is an important proxy for overall plant biomass and health. However, the manual measurement of stem diameter in plants is time consuming, error prone, and laborious. The use of agricultural robots to automatically collect plant phenotypic data for trait measurements can overcome many of the drawbacks of manual phenotyping. The objective of this research was to develop a robotic system that can automatically detect and grasp the stem, and measure its diameter of maize and sorghum plants. The robotic system comprises of a four degree of freedom robotic manipulator, a time-of-flight camera for vision system, and a linear potentiometer sensor to measure the stem diameter. Deep learning and conventional image processing were used to detect stem in images and find grasping point of stem, respectively. An experiment was conducted in a greenhouse using maize and sorghum plants to evaluate the performance of the robotic system. The system demonstrated successful grasping of stem and a high correlation between manual and robotic measurements of diameter depicting its ability to be used as a prototype to integrate other sensors to measure different physiological and chemical attributes of the stem. Full article
(This article belongs to the Section Agricultural and Field Robotics)
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Communication
Is Artificial Man Still Far Away: Anthropomimetic Robots Versus Robomimetic Humans
Robotics 2020, 9(3), 57; https://doi.org/10.3390/robotics9030057 - 24 Jul 2020
Cited by 1 | Viewed by 2141
Abstract
The article presents a viewpoint on the current status and limitations of humanoid robotics and possible future progress. It may be seen as a continuation of the article “How far away is artificial man?” published in 2001 by a group of authors, among [...] Read more.
The article presents a viewpoint on the current status and limitations of humanoid robotics and possible future progress. It may be seen as a continuation of the article “How far away is artificial man?” published in 2001 by a group of authors, among them the author of the present text, in IEEE Robotics &Automation Magazine (IEEE RAM). The previous article defined three key aspects of advanced humanoids, namely human-like shape and motion, intelligence, and communication. The current article discusses the situation 18 years later and takes note of the trend towards biologically inspired solutions to technical problems. It might appear to put forward controversial ideas, but the author believes they are realistic observations and constitute a frank presentation of apparent tendencies. The author argues that the crucial breakthrough towards an “artificial man” has not yet been made, as formidable challenges remain and cannot be overcome easily in the near future. On the other hand, the question arises: After unsuccessful attempts to solve robotic problems by designing technical systems that increasingly imitate humans, can we finally drop out of engineering and completely turn to biology and look for solutions there? This controversial idea means artificial creation and mass production of human beings that behave like robots, i.e., robomimetic humans. The article is a brief reality check of this concept. Full article
(This article belongs to the Special Issue Feature Papers 2020)
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Article
Comparison of Three Off-the-Shelf Visual Odometry Systems
Robotics 2020, 9(3), 56; https://doi.org/10.3390/robotics9030056 - 21 Jul 2020
Cited by 3 | Viewed by 2429
Abstract
Positioning is an essential aspect of robot navigation, and visual odometry an important technique for continuous updating the internal information about robot position, especially indoors without GPS (Global Positioning System). Visual odometry is using one or more cameras to find visual clues and [...] Read more.
Positioning is an essential aspect of robot navigation, and visual odometry an important technique for continuous updating the internal information about robot position, especially indoors without GPS (Global Positioning System). Visual odometry is using one or more cameras to find visual clues and estimate robot movements in 3D relatively. Recent progress has been made, especially with fully integrated systems such as the RealSense T265 from Intel, which is the focus of this article. We compare between each other three visual odometry systems (and one wheel odometry, as a known baseline), on a ground robot. We do so in eight scenarios, varying the speed, the number of visual features, and with or without humans walking in the field of view. We continuously measure the position error in translation and rotation thanks to a ground truth positioning system. Our result shows that all odometry systems are challenged, but in different ways. The RealSense T265 and the ZED Mini have comparable performance, better than our baseline ORB-SLAM2 (mono-lens without inertial measurement unit (IMU)) but not excellent. In conclusion, a single odometry system might still not be sufficient, so using multiple instances and sensor fusion approaches are necessary while waiting for additional research and further improved products. Full article
(This article belongs to the Section Sensors and Control in Robotics)
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Review
Possible Life Saver: A Review on Human Fall Detection Technology
Robotics 2020, 9(3), 55; https://doi.org/10.3390/robotics9030055 - 19 Jul 2020
Cited by 7 | Viewed by 2263
Abstract
Among humans, falls are a serious health problem causing severe injuries and even death for the elderly population. Besides, falls are also a major safety threat to bikers, skiers, construction workers, and others. Fortunately, with the advancements of technologies, the number of proposed [...] Read more.
Among humans, falls are a serious health problem causing severe injuries and even death for the elderly population. Besides, falls are also a major safety threat to bikers, skiers, construction workers, and others. Fortunately, with the advancements of technologies, the number of proposed fall detection systems and devices has increased dramatically and some of them are already in the market. Fall detection devices/systems can be categorized based on their architectures as wearable devices, ambient systems, image processing-based systems, and hybrid systems, which employ a combination of two or more of these methodologies. In this review paper, a comparison is made among these major fall detection systems, devices, and algorithms in terms of their proposed approaches and measure of performance. Issues with the current systems such as lack of portability and reliability are presented as well. Development trends such as the use of smartphones, machine learning, and EEG are recognized. Challenges with privacy issues, limited real fall data, and ergonomic design deficiency are also discussed. Full article
(This article belongs to the Special Issue Intelligent Medical Robotics)
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Article
Probabilistic Allocation of Specialized Robots on Targets Detected Using Deep Learning Networks
Robotics 2020, 9(3), 54; https://doi.org/10.3390/robotics9030054 - 16 Jul 2020
Viewed by 1673
Abstract
Task allocation for specialized unmanned robotic agents is addressed in this paper. Based on the assumptions that each individual robotic agent possesses specialized capabilities and that targets representing the tasks to be performed in the surrounding environment impose specific requirements, the proposed approach [...] Read more.
Task allocation for specialized unmanned robotic agents is addressed in this paper. Based on the assumptions that each individual robotic agent possesses specialized capabilities and that targets representing the tasks to be performed in the surrounding environment impose specific requirements, the proposed approach computes task-agent fitting probabilities to efficiently match the available robotic agents with the detected targets. The framework is supported by a deep learning method with an object instance segmentation capability, Mask R-CNN, that is adapted to provide target object recognition and localization estimates from vision sensors mounted on the robotic agents. Experimental validation, for indoor search-and-rescue (SAR) scenarios, is conducted and results demonstrate the reliability and efficiency of the proposed approach. Full article
(This article belongs to the Special Issue Robotics and Automation Engineering)
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Article
Synthesis and Analysis of a Novel Linkage Mechanism with the Helical Motion of the End-Effector
Robotics 2020, 9(3), 53; https://doi.org/10.3390/robotics9030053 - 08 Jul 2020
Viewed by 2249
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)
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Article
Finite Element Modeling in the Design Process of 3D Printed Pneumatic Soft Actuators and Sensors
Robotics 2020, 9(3), 52; https://doi.org/10.3390/robotics9030052 - 07 Jul 2020
Cited by 6 | Viewed by 3086
Abstract
The modeling of soft structures, actuators, and sensors is challenging, primarily due to the high nonlinearities involved in such soft robotic systems. Finite element modeling (FEM) is an effective technique to represent soft and deformable robotic systems containing geometric nonlinearities due to large [...] Read more.
The modeling of soft structures, actuators, and sensors is challenging, primarily due to the high nonlinearities involved in such soft robotic systems. Finite element modeling (FEM) is an effective technique to represent soft and deformable robotic systems containing geometric nonlinearities due to large mechanical deformations, material nonlinearities due to the inherent nonlinear behavior of the materials (i.e., stress-strain behavior) involved in such systems, and contact nonlinearities due to the surfaces that come into contact upon deformation. Prior to the fabrication of such soft robotic systems, FEM can be used to predict their behavior efficiently and accurately under various inputs and optimize their performance and topology to meet certain design and performance requirements. In this article, we present the implementation of FEM in the design process of directly three-dimensional (3D) printed pneumatic soft actuators and sensors to accurately predict their behavior and optimize their performance and topology. We present numerical and experimental results to show that this approach is very effective to rapidly and efficiently design the soft actuators and sensors to meet certain design requirements and to save time, modeling, design, and fabrication resources. Full article
(This article belongs to the Special Issue Feature Papers 2020)
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Article
Least Squares Optimization: From Theory to Practice
Robotics 2020, 9(3), 51; https://doi.org/10.3390/robotics9030051 - 01 Jul 2020
Cited by 3 | Viewed by 2574
Abstract
Nowadays, Nonlinear Least-Squares embodies the foundation of many Robotics and Computer Vision systems. The research community deeply investigated this topic in the last few years, and this resulted in the development of several open-source solvers to approach constantly increasing classes of problems. In [...] Read more.
Nowadays, Nonlinear Least-Squares embodies the foundation of many Robotics and Computer Vision systems. The research community deeply investigated this topic in the last few years, and this resulted in the development of several open-source solvers to approach constantly increasing classes of problems. In this work, we propose a unified methodology to design and develop efficient Least-Squares Optimization algorithms, focusing on the structures and patterns of each specific domain. Furthermore, we present a novel open-source optimization system that addresses problems transparently with a different structure and designed to be easy to extend. The system is written in modern C++ and runs efficiently on embedded systemsWe validated our approach by conducting comparative experiments on several problems using standard datasets. The results show that our system achieves state-of-the-art performances in all tested scenarios. Full article
(This article belongs to the Section Industrial Robots & Automation)
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Article
Kineto-Elasto-Static Design of Underactuated Chopstick-Type Gripper Mechanism for Meal-Assistance Robot
Robotics 2020, 9(3), 50; https://doi.org/10.3390/robotics9030050 - 30 Jun 2020
Viewed by 2159
Abstract
Our research aims at developing a meal-assistance robot with vision system and multi-gripper that enables frail elderly to live more independently. This paper presents a development of a chopstick-type gripper for a meal-assistance robot, which is capable of adapting its shape and contact [...] Read more.
Our research aims at developing a meal-assistance robot with vision system and multi-gripper that enables frail elderly to live more independently. This paper presents a development of a chopstick-type gripper for a meal-assistance robot, which is capable of adapting its shape and contact force with the target food according to the size and the stiffness. By solely using position control of the driving motor, the above feature is enabled without relying on force sensors. The gripper was designed based on the concept of planar 2-DOF under-actuated mechanism composed of a pair of four-bar chains having a torsion spring at one of the passive joints. To clarify the gripping motion and relationship among the contact force, food’s size and stiffness, and gripping position, kineto-elasto-static analysis of the mechanism was carried out. It was found from the result of the analysis that the mechanism was able to change its gripping force according to the contact position with the target object, and this mechanical characteristic was utilized in its grasp planning in which the position for the gripping the object was determined to realize a simple control system, and sensitivity of the contact force due to the error of the stiffness value was revealed. Using a three-dimensional (3D) printed prototype, an experiment to measure the gripping force by changing the contact position was conducted to validate the mechanism feature that can change its gripping force according to the size and the stiffness and the contact force from the analysis results. Finally, the gripper prototype was implemented to a 6-DOF robotic arm and an experiment to grasp real food was carried out to demonstrate the feasibility of the proposed grasp planning. Full article
(This article belongs to the Special Issue Kinematics and Robot Design III, KaRD2020)
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Article
Model-Free Optimized Tracking Control Heuristic
Robotics 2020, 9(3), 49; https://doi.org/10.3390/robotics9030049 - 29 Jun 2020
Cited by 1 | Viewed by 1872
Abstract
Many tracking control solutions proposed in the literature rely on various forms of tracking error signals at the expense of possibly overlooking other dynamic criteria, such as optimizing the control effort, overshoot, and settling time, for example. In this article, a model-free control [...] Read more.
Many tracking control solutions proposed in the literature rely on various forms of tracking error signals at the expense of possibly overlooking other dynamic criteria, such as optimizing the control effort, overshoot, and settling time, for example. In this article, a model-free control architectural framework is presented to track reference signals while optimizing other criteria as per the designer’s preference. The control architecture is model-free in the sense that the plant’s dynamics do not have to be known in advance. To this end, we propose and compare four tracking control algorithms which synergistically integrate a few machine learning tools to compromise between tracking a reference signal and optimizing a user-defined dynamic cost function. This is accomplished via two orchestrated control loops, one for tracking and one for optimization. Two control algorithms are designed and compared for the tracking loop. The first is based on reinforcement learning while the second is based on nonlinear threshold accepting technique. The optimization control loop is implemented using an artificial neural network. Each controller is trained offline before being integrated in the aggregate control system. Simulation results of three scenarios with various complexities demonstrated the effectiveness of the proposed control schemes in forcing the tracking error to converge while minimizing a pre-defined system-wide objective function. Full article
(This article belongs to the Special Issue Reinforcement Learning for Robotics Applications)
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