A wrench-sensitive touch pad based on a parallel structure

Trabajo presentado al ICRA 2008 celebrado en Pasadena (USA) del 19 al 23 de mayo.Many different robotic in-parallel structures have been conceived as six-component force sensors. In general, they perform well for most applications but, when accuracy is a must, two main limitations arise. First, in most designs, the legs are connected to the base and the platform through ball-and-socket joints. Although the dry friction in each of these joints can be individually neglected, the integrated effect of twelve such elements becomes noticeable. Second, dynamical measurements might not be very accurate because the natural resonance frequency of the used structures is quite low even for relatively small dimensions. This dynamical response can be obviously modified with a proper mechanical design, but this increases the complexity of the sensor. This paper discusses the design and implementation of a touch pad based on a 6-axis force sensor and shows how the above limitations degrade its behavior. Moreover, it is shown how using a tensegrity structure both problems could be alleviated because ball-and- socket joints can be substituted by point contacts and the resonance frequency of the structure can be controlled by adjusting the static tensions of the tendons.This work was supported by projects: 'Analysis and motion planning of complex robotic systems' (4802), 'Plataforma torsométrica basada en estructuras de tensigridad' (3707), 'Estació de muntatge universal' (I-00907). This work has been partially supported by the Spanish Ministry of Education and Science through the I+D project DPI2007-60858, by the XARTAP network of the Catalan Government, and by the Spanish I3 project with reference 2006-5-01-077.Peer Reviewe

eDIM: further development of the method to assess the ease of disassembly and reassembly of products: Application to notebook computers

The goal of this research is to further develop the eDIM method based on a new application to some exemplary laptops, also referred to as notebooks, which is a product group that is under review for the Eco-design Directive. This study aims at evaluating the applicability of the eDIM method as a standardised method for the assessment of the ability to access or non-destructively remove and reassemble certain components/assemblies from products. The scope of this study is limited to non-destructive, also refered to as reversible, disassembly and reassembly for the purpose of repair, remanufacture and reuse. In addition, the method has been further revised to address comments received from different stakeholders on the technical report outlining the eDIM method and during the presentation of the “Study for a method to assess the ease of disassembly of electrical and electronic equipment”. All comments received, which will be addressed in the presented study, relate to the following main topics: - Applicability of the eDIM method to a broader range of products including small, portable electronics. - Applicability of the eDIM method for other types of connectors, such as glues requiring wedge/pry and peel actions to be released - Applicability of the eDIM method for partial disassembly, different levels of disassembly, reassembly and how to deal with the allocation of the (re)disassembly time for components that need to be disassembled sequentially. - Applicability of the eDIM method to identify potential improvements for product’s designs.JRC.D.3-Land Resource

An optically actuated surface scanning probe

We demonstrate the use of an extended, optically trapped probe that is capable of imaging surface topography with nanometre precision, whilst applying ultra-low, femto-Newton sized forces. This degree of precision and sensitivity is acquired through three distinct strategies. First, the probe itself is shaped in such a way as to soften the trap along the sensing axis and stiffen it in transverse directions. Next, these characteristics are enhanced by selectively position clamping independent motions of the probe. Finally, force clamping is used to refine the surface contact response. Detailed analyses are presented for each of these mechanisms. To test our sensor, we scan it laterally over a calibration sample consisting of a series of graduated steps, and demonstrate a height resolution of ∼ 11 nm. Using equipartition theory, we estimate that an average force of only ∼ 140 fN is exerted on the sample during the scan, making this technique ideal for the investigation of delicate biological samples

Index to 1981 NASA Tech Briefs, volume 6, numbers 1-4

Short announcements of new technology derived from the R&D activities of NASA are presented. These briefs emphasize information considered likely to be transferrable across industrial, regional, or disciplinary lines and are issued to encourage commercial application. This index for 1981 Tech Briefs contains abstracts and four indexes: subject, personal author, originating center, and Tech Brief Number. The following areas are covered: electronic components and circuits, electronic systems, physical sciences, materials, life sciences, mechanics, machinery, fabrication technology, and mathematics and information sciences

Dexterous grippers: between simple industrial grippers and complex robotic hands

This thesis addresses the issue of introducing dexterity, namely the ability to manipulate objects in hand, into simple mechanical grippers. Among the many possibilities to give dexterity to a gripping device we opted to intervene at the finger-pad surface since it is the part of the end effector directly in contact with the object to be manipulated. The first contribution is the development of an under-actuated gripper with Active Surfaces on the inner side of the fingers which allow to in-hand manipulate the grasped objects. The gripper, named Velvet Fingers, was designed from the theoretical concepts, manufactured, assembled and then turned into an applicative scenario. A second main contribution of this thesis, carried out in collaboration with AASS Research Center, of the University of \"Orebro (Sweden), is a grasp execution routine using the Active Surfaces of the Velvet Fingers to achieve a robust power grasp starting from an initial fingertip grasp. This routine is very useful and effective in cluttered environment where an initial fingertip grasp is much more likely to be feasible than a bulky power grasp. The third main contribution is the development of a small gripper for small household objects such as cans, small bottles, little boxes, tennis balls etc. This gripper, named Velvet-II, is able to perform in-hand manipulation tasks, to elicit information from the grasped object, namely the contact point location and the components of the grasping forces and to detect incipient slippage between the gripper and the object. Within a collaboration with AASS Research Center the gripper has been employed on a robotic platform for autonomous picking and palletizing

Exploring the Multi-touch Interaction Design Space for 3D Virtual Objects to Support Procedural Training Tasks

Multi-touch interaction has the potential to be an important input method for realistic training in 3D environments. However, multi-touch interaction has not been explored much in 3D tasks, especially when trying to leverage realistic, real-world interaction paradigms. A systematic inquiry into what realistic gestures look like for 3D environments is required to understand how users translate real-world motions to multi-touch motions. Once those gestures are defined, it is important to see how we can leverage those gestures to enhance training tasks. In order to explore the interaction design space for 3D virtual objects, we began by conducting our first study exploring user-defined gestures. From this work we identified a taxonomy and design guidelines for 3D multi-touch gestures and how perspective view plays a role in the chosen gesture. We also identified a desire to use pressure on capacitive touch screens. Since the best way to implement pressure still required some investigation, our second study evaluated two different pressure estimation techniques in two different scenarios. Once we had a taxonomy of gestures we wanted to examine whether implementing these realistic multi-touch interactions in a training environment provided training benefits. Our third study compared multi-touch interaction to standard 2D mouse interaction and to actual physical training and found that multi-touch interaction performed better than 2D mouse and as well as physical training. This study showed us that multi-touch training using a realistic gesture set can perform as well as training on the actual apparatus. One limitation of the first training study was that the user had constrained perspective to allow for us to focus on isolating the gestures. Since users can change their perspective in a real life training scenario and therefore gain spatial knowledge of components, we wanted to see if allowing users to alter their perspective helped or hindered training. Our final study compared training with Unconstrained multi-touch interaction, Constrained multi-touch interaction, or training on the actual physical apparatus. Results show that the Unconstrained multi-touch interaction and the Physical groups had significantly better performance scores than the Constrained multi-touch interaction group, with no significant difference between the Unconstrained multi-touch and Physical groups. Our results demonstrate that allowing users more freedom to manipulate objects as they would in the real world benefits training. In addition to the research already performed, we propose several avenues for future research into the interaction design space for 3D virtual objects that we believe will be of value to researchers and designers of 3D multi-touch training environments

Objekt-Manipulation und Steuerung der Greifkraft durch Verwendung von Taktilen Sensoren

This dissertation describes a new type of tactile sensor and an improved version of the dynamic tactile sensing approach that can provide a regularly updated and accurate estimate of minimum applied forces for use in the control of gripper manipulation. The pre-slip sensing algorithm is proposed and implemented into two-finger robot gripper. An algorithm that can discriminate between types of contact surface and recognize objects at the contact stage is also proposed. A technique for recognizing objects using tactile sensor arrays, and a method based on the quadric surface parameter for classifying grasped objects is described. Tactile arrays can recognize surface types on contact, making it possible for a tactile system to recognize translation, rotation, and scaling of an object independently.Diese Dissertation beschreibt eine neue Art von taktilen Sensoren und einen verbesserten Ansatz zur dynamischen Erfassung von taktilen daten, der in regelmäßigen Zeitabständen eine genaue Bewertung der minimalen Greifkraft liefert, die zur Steuerung des Greifers nötig ist. Ein Berechnungsverfahren zur Voraussage des Schlupfs, das in einen Zwei-Finger-Greifarm eines Roboters eingebaut wurde, wird vorgestellt. Auch ein Algorithmus zur Unterscheidung von verschiedenen Oberflächenarten und zur Erkennung von Objektformen bei der Berührung wird vorgestellt. Ein Verfahren zur Objekterkennung mit Hilfe einer Matrix aus taktilen Sensoren und eine Methode zur Klassifikation ergriffener Objekte, basierend auf den Daten einer rechteckigen Oberfläche, werden beschrieben. Mit Hilfe dieser Matrix können unter schiedliche Arten von Oberflächen bei Berührung erkannt werden, was es für das Tastsystem möglich macht, Verschiebung, Drehung und Größe eines Objektes unabhängig voneinander zu erkennen

Grasping complex casting shapes with an underactuated parallel jaw gripper on an industrial robot

Steel foundries are in great need of automation as current operations involve many hazardous manual tasks. Automating foundry operations is very challenging due to the variety of tasks that must be performed on physical objects that vary significantly in size, shape, and weight. This thesis focuses on robotically automating the material handling operation in the foundry by designing an underactuated parallel jaw robotic gripper that can handle a variety of foundry products regardless of their shape. This design is driven by a linear underactuated system composed of a series of coupled hydraulic pistons that enable the gripper to securely grasp objects by conforming to their shape. In the course of evaluating this problem, two main contributions have emerged: (i) A method is presented that uses physics-based simulations to optimize the design of the underactuated parallel jaw gripper for grasping a variety of steel foundry operations. (ii) The resultant design is then validated on a physical industrial robot to show that the underactuated parallel jaw gripper is 30% more effective at grasping typical casting shapes when compared with the standard parallel jaw gripper and 280% better than a similar underactuated robot gripper using revolute fingers

Robot skill learning through human demonstration and interaction

Nowadays robots are increasingly involved in more complex and less structured tasks. Therefore, it is highly desirable to develop new approaches to fast robot skill acquisition. This research is aimed to develop an overall framework for robot skill learning through human demonstration and interaction. Through low-level demonstration and interaction with humans, the robot can learn basic skills. These basic skills are treated as primitive actions. In high-level learning, the complex skills demonstrated by the human can be automatically translated into skill scripts which are executed by the robot. This dissertation summarizes my major research activities in robot skill learning. First, a framework for Programming by Demonstration (PbD) with reinforcement learning for human-robot collaborative manipulation tasks is described. With this framework, the robot can learn low level skills such as collaborating with a human to lift a table successfully and efficiently. Second, to develop a high-level skill acquisition system, we explore the use of a 3D sensor to recognize human actions. A Kinect based action recognition system is implemented which considers both object/action dependencies and the sequential constraints. Third, we extend the action recognition framework by fusing information from multimodal sensors which can recognize fine assembly actions. Fourth, a Portable Assembly Demonstration (PAD) system is built which can automatically generate skill scripts from human demonstration. The skill script includes the object type, the tool, the action used, and the assembly state. Finally, the generated skill scripts are implemented by a dual-arm robot. The proposed framework was experimentally evaluated