Showing papers in "IEEE Robotics & Automation Magazine in 2014"

Vision-Controlled Micro Flying Robots: From System Design to Autonomous Navigation and Mapping in GPS-Denied Environments

Abstract: Autonomous microhelicopters will soon play a major role in tasks like search and rescue, environment monitoring, security surveillance, and inspection. If they are further realized in small scale, they can also be used in narrow outdoor and indoor environments and represent only a limited risk for people. However, for such operations, navigating based only on global positioning system (GPS) information is not sufficient. Fully autonomous operation in cities or other dense environments requires microhelicopters to fly at low altitudes, where GPS signals are often shadowed, or indoors and to actively explore unknown environments while avoiding collisions and creating maps. This involves a number of challenges on all levels of helicopter design, perception, actuation, control, and navigation, which still have to be solved. The Swarm of Micro Flying Robots (SFLY) project was a European Union-funded project with the goal of creating a swarm of vision-controlled microaerial vehicles (MAVs) capable of autonomous navigation, three-dimensional (3-D) mapping, and optimal surveillance coverage in GPS-denied environments. The SFLY MAVs do not rely on remote control, radio beacons, or motion-capture systems but can fly all by themselves using only a single onboard camera and an inertial measurement unit (IMU). This article describes the technical challenges that have been faced and the results achieved from hardware design and embedded programming to vision-based navigation and mapping, with an overview of how all the modules work and how they have been integrated into the final system. Code, data sets, and videos are publicly available to the robotics community. Experimental results demonstrating three MAVs navigating autonomously in an unknown GPS-denied environment and performing 3-D mapping and optimal surveillance coverage are presented.

Stronger, Smarter, Softer: Next-Generation Wearable Robots

Abstract: Exosuits show much promise as a method for augmenting the body with lightweight, portable, and compliant wearable systems. We envision that such systems can be further refined so that they can be sufficiently low profile to fit under a wearer's existing clothing. Our focus is on creating an assistive device that provides a fraction of the nominal biological torques and does not provide external load transfer. In early work, we showed that the system can substantially maintain normal biomechanics and positively affect a wearer's metabolic rate. Many basic fundamental research and development challenges remain in actuator development, textile innovation, soft sensor development, human-machine interface (control), biomechanics, and physiology, which provides fertile ground for academic research in many disciplines. While we have focused on gait assistance thus far, numerous other applications are possible, including rehabilitation, upper body support, and assistance for other motions. We look forward to a future where wearable robots provide benefits for people across many areas of our society.

A Robotic Leg Prosthesis: Design, Control, and Implementation

Abstract: This article describes the design and control of a powered knee and ankle prosthesis for transfemoral amputees. Following a description of the design hardware, a hybrid control approach that provides coordination for level walking is described. The hybrid control approach combines a piecewise-passive impedance-based component during the stance phase of gait with a high impedance trajectory-tracking component during the terminal stance and swing. To validate the design, the controller was implemented on the powered prosthesis prototype, and its ability to provide level walking functionality was evaluated on three transfemoral amputee subjects. The data presented from these experimental trials indicate that the prosthesis and control approach reproduce knee and ankle joint kinematic and kinetic features that are highly representative of corresponding healthy joint biomechanics.

The Feel of MEMS Barometers: Inexpensive and Easily Customized Tactile Array Sensors

Abstract: This article presents a new approach to the construction of tactile array sensors based on barometric pressure sensor chips and standard printed circuit boards (PCBs). The chips include tightly integrated instrumentation amplifiers, analog-to-digital converters, pressure and temperature sensors, and control circuitry that provides excellent signal quality over standard digital bus interfaces. The resulting array electronics can be easily encapsulated with soft polymers to provide robust and compliant grasping surfaces for specific hand designs. The use of standard commercial off-the-shelf technologies means that only basic electrical and mechanical skills are required to build effective tactile sensors for new applications. The performance evaluation of prototype arrays demonstrates excellent linearity (typically <;1%) and low noise (<;0.01 N). External addressing circuitry allows multiple sensors to communicate on the same bus at more than 100 Hz per sensor element. Sensors can be mounted with as close as 3#5-mm spacing, and spatial impulse response tests show that linear solid-mechanics-based signal processing is feasible. This approach promises to make sensitive, robust, and inexpensive tactile sensing available for a wide range of robotics and human-interface applications.

Developing an Aerial Manipulator Prototype: Physical Interaction with the Environment

Abstract: This article focuses on the design, modeling, and control of an aerial manipulator prototype, i.e., an innovative configuration consisting of a miniature quadrotor helicopter endowed with a robotic manipulator. The overall system is designed to accomplish operations that require physical interaction with the surrounding environment while remaining airborne. To investigate the dynamical model of the aerial manipulator, a simple planar benchmark is used to analyze the interactions between the quadrotor, the robotic manipulator, and the environment. A control strategy for the planar system is designed to guarantee robustness in the presence or absence of contacts. Experiments on a real setup validate the control in the two different scenarios in which the aerial manipulator is either freely flying or physically interacting with the environment.

The Safety of Domestic Robotics: A Survey of Various Safety-Related Publications

Abstract: Different branches of technology are striving to come up with new advancements that will enhance civilization and ultimately improve the quality of life. In the robotics community, strides have been made to bring the use of personal robots in office and home environments on the horizon. Safety is one of the critical issues that must be guaranteed for the successful acceptance, deployment, and utilization of domestic robots. Unlike the barrier-based operational safety guarantee that is widely used in industrial robotics, safety in domestic robotics deals with a number of issues, such as intrinsic safety, collision avoidance, human detection, and advanced control techniques. In the last decade, a number of researchers have presented their works that highlighted the issue of safety in a specific part of the complete domestic robotics system. This article presents a general survey of various safety-related publications that focus on safety criteria and metrics, mechanical design and actuation, and controller design.

The Body Extender: A Full-Body Exoskeleton for the Transport and Handling of Heavy Loads

Abstract: This article introduces and describes an electrically powered full-body (FB) exoskeleton, called the body extender (BE), intended as a research platform for the study of the transport and handling of heavy loads up to 50 kg, with one hand at worst-load conditions (WLCs). The machine features a 22-degrees-of-freedom (DoF) quasi-anthropomorphic kinematic scheme and a modular hardware/software architecture that made it possible to manage the complexity of the system design. Besides providing a context and some general guidelines, which have driven the design of the BE, this article presents the hardware and software developments that have been achieved and implemented in the machine. The experimental results are shown that prove the functionalities of the BE in common operating conditions such as walking, squatting, and handling loads. The one-of-a-kind system demonstrates, in relevant laboratory settings, the feasibility of a complex, electrically powered full-body exoskeleton with such a target payload.

Model-Predictive Motion Planning: Several Key Developments for Autonomous Mobile Robots

Abstract: A necessary attribute of a mobile robot planning algorithm is the ability to accurately predict the consequences of robot actions to make informed decisions about where and how to drive. It is also important that such methods are efficient, as onboard computational resources are typically limited and fast planning rates are often required. In this article, we present several practical mobile robot motion planning algorithms for local and global search, developed with a common underlying trajectory generation framework for use in model-predictive control. These techniques all center on the idea of generating informed, feasible graphs at scales and resolutions that respect computational and temporal constraints of the application. Connectivity in these graphs is provided by a trajectory generator that searches in a parameterized space of robot inputs subject to an arbitrary predictive motion model. Local search graphs connect the currently observed state-to-states at or near the planning or perception horizon. Global search graphs repeatedly expand a precomputed trajectory library in a uniformly distributed state lattice to form a recombinant search space that respects differential constraints. In this article, we discuss the trajectory generation algorithm, methods for online or offline calibration of predictive motion models, sampling strategies for local search graphs that exploit global guidance and environmental information for real-time obstacle avoidance and navigation, and methods for efficient design of global search graphs with attention to optimality, feasibility, and computational complexity of heuristic search. The model-invariant nature of our approach to local and global motions planning has enabled a rapid and successful application of these techniques to a variety of platforms. Throughout the article, we also review experiments performed on planetary rovers, field robots, mobile manipulators, and autonomous automobiles and discuss future directions of the article.

XPED2: A Passive Exoskeleton with Artificial Tendons

Abstract: Wearable exoskeletons might reduce human effort during walking. However, many of the current exoskeletons rely on heavy actuators and/or external power supplies; this has a negative impact on their efficiency and operation range. As an alternative, (quasi)passive exoskeletons have been developed. One of the proposed passive exoskeleton concepts is the exotendon concept of van den Bogert [1]. In this concept, long elastic cables span multiple joints. The cables can temporarily store and transfer energy between joints. In simulation, the average absolute joint torque can be reduced by 71%. The simulations are based on the hypotheses 1) that the exoskeleton does not influence the joint angles and 2) the total joint torques and a reduction in the human joint torques results in a reduction in the metabolic cost of walking. The goal of this article is to experimentally evaluate the exotendon concept and test the hypotheses underlying it. We implemented the exotendon concept in a lightweight exoskeleton. Experimental results show that the exotendons indeed reduced the average absolute joint torques. However, the exotendons also influenced the joint kinematics, and the metabolic cost of walking did not decrease. Therefore, the underlying assumptions of the exotendon concept are invalid. We also found that, in practice, the amount of support given by the exotendons is limited to about 35% of the theoretical optimal support. For higher levels of support, the motion is hindered and the support is experienced as uncomfortable by the users of the exoskeleton.

SLAM Gets a PHD: New Concepts in Map Estimation

Abstract: Having been referred to as the Holy Grail of autonomous robotics research, simultaneous localization and mapping (SLAM) lies at the core of most the autonomous robotic applications [1]. This article explains the recent advances in the representations of robotic sensor measurements and the map itself as well as their consequences on the robustness of SLAM. Fundamentally, the concept of a set-based measurement and map state representation allows all of the measurement information, spatial and detection, to be incorporated into joint Bayesian SLAM frameworks. Modeling measurements and the map state as random finite sets (RFSs) rather than the traditionally adopted random vectors is not merely a triviality of notation. It will be demonstrated that a set-based framework circumvents the necessity for any fragile data association and map management heuristics, which are necessary in vectorbased solutions.

Speed-Adaptation Mechanism: Robotic Prostheses Can Actively Regulate Joint Torque

Abstract: By 2050, an estimated 1.5 million people in the United States will be living with a major lower-limb amputation [1], a condition that causes severe disability, particularly for persons with transfemoral (above-knee) amputations. These individuals expend up to twice the metabolic effort to walk at half the speed [2] of able-bodied persons, and they experience a higher risk of falls and secondary pathological conditions, such as osteoarthritis, back pain, and depression [3].

FILOSE for Svenning: A Flow Sensing Bioinspired Robot

Abstract: The trend of biomimetic underwater robots has emerged as a search for an alternative to traditional propeller-driven underwater vehicles. The drive of this trend, as in any other areas of bioinspired and biomimetic robotics, is the belief that exploiting solutions that evolution has already optimized leads to more advanced technologies and devices. In underwater robotics, bioinspired design is expected to offer more energy-efficient, highly maneuverable, agile, robust, and stable underwater robots. The 30,000 fish species have inspired roboticists to mimic tuna [1], rays [2], boxfish [3], eels [4], and others. The development of the first commercialized fish robot Ghostswimmer by Boston Engineering and the development of fish robots for field trials with specific applications in mind (http://www.roboshoal. com) mark a new degree of maturity of this engineering discipline after decades of laboratory trials.

Group Mapping: A Topological Approach to Map Merging for Multiple Robots

Abstract: Simultaneous localization and mapping (SLAM) is required for mobile robots to be able to explore a prior unknown space without a global positioning reference. Multiple robots can achieve exploration tasks more quickly but with added complexity. A useful representation of the map for SLAM purposes is as an occupancy grid map. In the most general case of multiple-robot SLAM, occupancy grid maps from multiple agents must be merged in real time without any prior knowledge of their relative transformation. In addition, the probabilistic information of the maps must be accounted for and fused accordingly. In this article, the generalized Voronoi diagram (GVD) is extended to encapsulate the probabilistic information encoded in the occupancy grid map. The new construct called the probabilistic GVD (PGVD) operates directly on occupancy grid maps and is used to determine the relative transformation between maps and fuse them. This approach has three major benefits over past methods: 1) it is effective at finding relative transformations quickly and reliably, 2) the uncertainty associated with transformations used to fuse the maps is accounted for, and 3) the parts of the maps that are more certain are preferentially used in the merging process because of the probabilistic nature of the PGVD.

Adaptable Robot Formation Control: Adaptive and Predictive Formation Control of Autonomous Vehicles

Abstract: The ability to use cooperative small vehicles is of interest in many applications. From material transportation to farming operations, the use of small machines achieving small tasks, but able to work together to complete larger tasks, permits us to rely on a unique kind of vehicle. To be efficient, such a point of view requires the vehicles to be, at least partially, autonomous and their motion must be accurately coordinated for the tasks to be properly achieved. This article proposes a control framework dedicated to the accurate control of a fleet of mobile robots operating in formation. Decentralized control relying on interrobot communication has been favored. To ensure a high relative positioning, adaptive and predictive control techniques are considered, allowing us to account for the influence of several phenomena (such as dynamic perturbations or bad grip conditions) depreciating the relevance of classical approaches based on ideal robots and ideal contact conditions assumptions.

Bilateral Robot Teleoperation: A Wearable Arm Exoskeleton Featuring an Intuitive User Interface

Abstract: Teleoperation systems are used when human planning and decision-making capabilities are needed during robotic remote operations. To execute meaningful tasks remotely, the operator has to be able to simultaneously control multiple degrees of freedom (DoFs) of the slave robot and efficiently receive information from the remote site. In these cases, haptic feedback has been shown to improve the operator's task execution performance [1].

CYBERLEGs: A user-oriented robotic transfemoral prosthesis with whole-body awareness control

Abstract: Restoring the mobility of transfemoral dysvascular amputees is essential to their rehabilitation process. Impeding the restoration of mobility, exhaustion is often the cause of noneffective deambulation of elderly lowerlimb amputees using a prosthesis as they use more energy for locomotion than younger amputees do. This article presents finite-state control of a novel powered prosthesis prototype for transfemoral amputees based on whole-body awareness. Intention detection was implemented through a noninvasive, distributed wireless wearable sensory system. The cybernetic lower-limb cognitive orthoprosthesis (CYBERLEGs) system was evaluated in a study involving three amputees. The subjects were able to walk with the prosthesis without training, showing accurate performance of the intention detection. The functionality of the CYBERLEGs approach was confirmed by gait pattern analysis and intention detection statistics.

Optical Tweezers: Autonomous Robots for the Manipulation of Biological Cells

Abstract: Optical tweezers (OTs) are a popular tool for manipulating biological objects, especially cells [1], [2]. Using a tightly focused laser beam, they exert sufficient forces to tweeze, i.e., hold (trap) and move, freely diffusing cells in the vicinity of the beam focus. The beam can be focused at any point in the workspace, which is typically a liquid-filled glass slide. The trapped cell can, thus, be translated and rotated (transported) in three dimensions by changing the beam focus position. OTs provide certain advantages over other cell-manipulation techniques. They are able to manipulate cells with a greater degree of precision as compared with microfluidic flow. Significant contact forces are not exerted on the cells, unlike in mechanical manipulation, thereby avoiding damages due to contact friction or surface chemistry. The cells are also easily released at the end of the manipulation by simply switching off the laser beam. Hence, OTs have been extensively used for mechanical characterization of cells by measuring their viscoelastic properties to distinguish between normal and diseased cells [3]. They have also been used for separating cells of different types [4] and investigating the response of cells to external stimuli [5]. However, manual or teleoperated control of the laser beam has limited their applicability for multicellular studies.

The CUIK Suite: Analyzing the Motion Closed-Chain Multibody Systems

Abstract: Many situations in robotics require the analysis of the motions of complex multibody systems. These are sets of articulated bodies arising in a variety of devices, including parallel manipulators, multifingered hands, or reconfigurable mechanisms, but they appear in other domains too as mechanical models of molecular compounds or nanostructures. Closed kinematic chains arise frequently in such systems, either due to their morphology or due to geometric or contact constraints to fulfill during operation, giving rise to configuration spaces of an intricate structure. Despite appearing very often in practice, there is a lack of general software tools to analyze and represent such configuration spaces. Existing packages are oriented either to open-chain systems or to specific robot types, which hinders the analysis and development of innovative manipulators. This article describes the CUIK suite, a software toolbox for the kinematic analysis of general multibody systems. The implemented tools can isolate the valid configurations, determine the motion range of the whole multibody system or of some of its parts, detect singular configurations leading to control or dexterity issues, or find collision- and singularity-free paths between configurations. The toolbox has applications in robot design and programming and is the result of several years of research and development within the Kinematics and Robot Design group at IRI, Barcelona. It is available under GPLv3 license from http://www.iri.upc.edu/cuik.

Robomorphism: A Nonanthropomorphic Wearable Robot

Abstract: This article describes a novel wearable robot (WR) intended to assist hip and knee flexion/ extension through series elastic actuators (SEAs) A nonanthropomorphic (NA) design was pursued to improve ergonomics while optimizing dynamic properties through a smart distribution of swinging masses Once the anthropomorphism constraint is relaxed, the number of possible architectures becomes very high, and a methodology must be defined to point out the best options To this purpose, a design methodology, which includes a novel approach to kinematic synthesis, topology selection, and morphological optimization, is also presented The advantages offered by the novel architecture are demonstrated both theoretically and experimentally In particular, the results show a low reflected inertia on the user's body, a high backdrivability, and an intrinsic tolerance to misalignments Such advantages make the proposed robot a promising platform for the development of assistive and rehabilitation systems

Detecting Unfocused Raindrops: In-Vehicle Multipurpose Cameras

Abstract: Advanced driver assistance systems (ADASs) based on video cameras are becoming pervasive in today's automotive industry. However, while most of these systems perform nicely in clear weather conditions, their performances fail drastically in adverse weather and particularly in the rain. We present two novel approaches that aim to detect unfocused raindrops on a car windshield using only images from an in-vehicle camera. Based on the photometric properties of raindrops, the algorithms rely on image processing techniques to highlight them. The results will be used to improve ADAS behavior under rainy conditions. Both approaches are compared with each other and the techniques from the literature.

RFS Collaborative Multivehicle SLAM: SLAM in Dynamic High-Clutter Environments

Abstract: Recently, we proposed a novel solution to the collaborative multivehicle simultaneous localization and mapping (CMSLAM) problem by extending the random finite set (RFS) SLAM filter framework using recently developed multisensor information fusion techniques in the finite set statistics. We modeled the measurements and the landmark map as RFSs, and a joint posterior consisting of the landmark map and the vehicle trajectories was propagated in time to solve the CMSLAM problem. The proposed solution is based on the Rao?Blackwellized particle filter-based vehicle trajectories posterior estimation and the probability hypothesis density (PHD) filter-based landmark map posterior estimation. In this article, we evaluate the performance of this solution under dynamic high-clutter environmental conditions using a series of simulations and an actual experiment.

SLAM with SC-PHD Filters: An Underwater Vehicle Application

Abstract: The random finite-set formulation for multiobject estimation provides a means of estimating the number of objects in cluttered environments with missed detections within a unified probabilistic framework. This methodology is now becoming the dominant mathematical framework within the sensor fusion community for developing multiple-target tracking algorithms. These techniques are also gaining traction in the field of feature-based simultaneous localization and mapping (SLAM) for mobile robotics. Here, we present one such instance of this approach with an underwater vehicle using a hierarchical multiobject estimation method for estimating both landmarks and vehicle position.

Random Set Methods: Estimation of Multiple Extended Objects

Abstract: Random set-based methods have provided a rigorous Bayesian framework and have been used extensively in the last decade for point object estimation. In this article, we emphasize that the same methodology offers an equally powerful approach to estimation of so-called extended objects, i.e., objects that result in multiple detections on the sensor side. Building upon the analogy between Bayesian state estimation of a single object and random finite set (RFS) estimation for multiple objects, we give a tutorial on random set methods with an emphasis on multiple-extended-object estimation. The capabilities are illustrated on a simple yet insightful real-life example with laser range data containing several occlusions.

A Robust Motion Detection Technique for Dynamic Environment Monitoring: A Framework for Grid-Based Monitoring of the Dynamic Environment

Abstract: The Bayesian occupancy filter (BOF) provides a framework for grid-based monitoring of the dynamic environment It allows us to estimate dynamic grids, containing both information of occupancy and velocity Clustering such grids then provides detection of the objects in the observed scene

Fostering Progress in Performance Evaluation and Benchmarking of Robotic and Automation Systems [TC Spotlight]

Abstract: We have shared benchmarks for many engineering systems and products in the market that can be used to compare solutions and systems. We can compare cars in terms of maximum speed, acceleration, and maximum torque; computers in terms of flops, random access memory, and hard disk capacity; and smartphones in terms of battery life and screen dimensions. We also have shared usability metrics based on human factors, which are used to compare the ease of use of different software interfaces. When we come to the evaluation and the comparison of how intelligent, robust, adaptive, and antifragile the behaviors of robots are in performing a given set of tasks, such as daily life activities with daily life objects such as in a kitchen or a hospital room, we are in trouble.

GNSS Autonomous Localization: NLOS Satellite Detection Based on 3-D Maps

Abstract: One of the main drawbacks of global navigation satellite systems (GNSSs) in urban environments is that signals may arrive at the receiver antenna only in nonline-of-sight (NLOS) conditions, leading to biased pseudorange estimates when they are taken for granted by the receiver and, eventually, wrong positioning. This article presents a study on the benefits of using three-dimensional (3-D) maps of cities to decide whether the GNSS signal coming from each tracked satellite is reliable. Based on this principle, two different 3-D maps and two methodologies are presented and compared. The results show the benefits of this approach.

Survey of Geodetic Mapping Methods: Geodetic Approaches to Mapping and the Relationship to Graph-Based SLAM

Abstract: The ability to simultaneously localize a robot and build a map of the environment is central to most robotics applications, and the problem is often referred to as simultaneous localization and mapping (SLAM). Robotics researchers have proposed a large variety of solutions allowing robots to build maps and use them for navigation. In addition, the geodetic community has addressed large-scale map building for centuries, computing maps that span across continents. These large-scale mapping processes had to deal with several challenges that are similar to those of the robotics community. In this article, we explain key geodetic map building methods that we believe are relevant for robot mapping. We also aim at providing a geodetic perspective on current state-of-the-art SLAM methods and identifying similarities both in terms of challenges faced and the solutions proposed by both communities. The central goal of this article is to connect both fields and enable future synergies between them.

Smart Building Technology [TC Spotlight]

Abstract: Buildings contribute to a significant amount of the total energy consumption in many developed and developing countries. For example, on an annual basis, buildings consume ~40% of the energy and 70% of the electricity in the United States. In China, the energy consumption of buildings has risen from 10 to 25% of the overall energy consumption of the country since 1978 and is predicted to increase by 35% every year in the coming years.

Patient-Tailored Assistance: A New Concept of Assistive Robotic Device That Adapts to Individual Users

Abstract: This article presents the development of a new concept for an assistive robotic device that can help people as needed, considering their residual physical and cognitive abilities, and, at the same time, increase their cognitive and physical abilities in activities of daily living (ADLs), such as drinking, cooking, eating, personal hygiene, and grooming.

Playing Fetch with Your Robot: The Ability of Robots to Locate and Interact with Objects

Abstract: The task addressed in this article is the localization of an unknown number of targets using a mobile robot equipped with a visual sensor. The estimation of the number of targets and their locations is done using a recursive Bayesian filter over random finite sets (RFSs), and the position of the robot is assumed to be known. We present a computationally tractable control law whereby the robot follows the gradient of mutual information between target locations and detections. The method is verified through real-world experimental trials, reliably detecting multiple targets and ignoring clutter obstacles.