Universal Robotic Gripper based on the Jamming of Granular Material

Gripping and holding of objects are key tasks for robotic manipulators. The development of universal grippers able to pick up unfamiliar objects of widely varying shape and surface properties remains, however, challenging. Most current designs are based on the multi-fingered hand, but this approach introduces hardware and software complexities. These include large numbers of controllable joints, the need for force sensing if objects are to be handled securely without crushing them, and the computational overhead to decide how much stress each finger should apply and where. Here we demonstrate a completely different approach to a universal gripper. Individual fingers are replaced by a single mass of granular material that, when pressed onto a target object, flows around it and conforms to its shape. Upon application of a vacuum the granular material contracts and hardens quickly to pinch and hold the object without requiring sensory feedback. We find that volume changes of less than 0.5% suffice to grip objects reliably and hold them with forces exceeding many times their weight. We show that the operating principle is the ability of granular materials to transition between an unjammed, deformable state and a jammed state with solid-like rigidity. We delineate three separate mechanisms, friction, suction and interlocking, that contribute to the gripping force. Using a simple model we relate each of them to the mechanical strength of the jammed state. This opens up new possibilities for the design of simple, yet highly adaptive systems that excel at fast gripping of complex objects.Comment: 10 pages, 7 figure

S:t Sigfrids granne : en begravningsplats för alla

This paper is about cemetaries in a multireligious society. The aim of the work is to compare the physical expressions of different religions burial traditions, in order to plan a multireligious cemetary in Borås. I´ve studied the five worldreligions, Judaism, Chritstianity, Islam, Buddhism and Hinduism. I´ve also written about the Humanism, a nonreligious organization, and funerals without any religious connection. Litterature studies gave basic knowledge about the religions beliefs, and interviews with a person from each group deepend the knowledge, mainly regarding the burial traditions. Interviews with landscape architects gave information about the most important aspects of the architecture of cemetaries. By visting cemetaries, I compared the information I gained through litterature and interviews with reality. The visits also gave inspiration for my own planning of the cemetary in Borås. There are many similarities among the burial traditions in Judaism, Christanity and Islam. The burial place has greater importance to them than to the Indian religions. In Buddhism and Hinduism they belive in reincarnation and therefore the grave and burial ground is not very important. The architecture of the cemetary is not as full of symbols as I expected it to be. The most important is the border to the surroundings and the entrance. When going through the entrance to the cemetary, the visitor should get a feeling of stepping in to another world. On the cemetary the graves are central and it is important to plan with respect for the people visiting a grave. During the work I´ve come to the conclusion that it is possible for different religions to share the same burial ground, as long as each religion has it´s own small area. One reason for this is that some religions celebrate ceremonies on the cemetary and this is easier if the graves are placed close to each other. Another reason is that recognizing symbols and words on neighbouring graves gives a feeling of security and confidence when visting a grave. In Borås there is a need for places to bury people who are not christian and there are plans to establish a new cemetary. I havn´t had a formal comission in Borås, but I´ve used the site of their new cemetary as a basis for my work. My idea for the new cemetary in Borås is a place full of light and flowers. The place is dominated of birchtrees (Betula pubescens). Between the trees are glades where the graves are placed. Each religious or nonreligious group has there own glade, with wellknown traditions and symbols. At the same time they are able to see and feel a connection to people in other parts of the cemetary. The different areas are not decided in advance for a specific religion, but are planned in detail when they´re taken in use.Det här arbetet handlar om begravningsplatser i ett multireligiöst samhälle. Arbetet syftar till att jämföra de fysiska uttrycken för olika religioners begravningstraditioner och utifrån detta planera en begravningsplats som kan passa alla. Ett område i Borås, i anslutning till S:t Sigfrids griftegård är utgångspunkt i gestaltningsarbetet. Jag har valt att studera och i gestaltningen ta hänsyn till de fem världsreligionerna, judendom, kristendom, islam, hinduism och buddhism. Utöver de religiösa grupperna behandlade jag begravning utan religiös anknytning och tog i det sammanhanget upp humanisterna (tidigare human-etiska förbundet). Litteraturstudier gav baskunskap om religionerna och intervjuer med en representant från varje grupp fördjupade kunskapen, främst i avseende på begravning och begravningsplatsen. Intervjuer med landskapsarkitekter ökade min kunskap om begravningsplatsens arkitektur. Genom studiebesök jämförde jag det jag lärt mig med hur det ser ut i verkligheten. Studiebesöken gav också inspiration inför mitt eget gestaltningsarbete. Det fi nns tydliga likheter i begravningstraditioner mellan de tre abrahamitiska religionerna, judendom, kristendom och islam. Det är också bland dessa som begravningsplatsen har störst betydelse och funktion för de efterlevande. I de indiska religionerna, buddhism och hinduism, tror man på reinkarnation och därför spelar platsen man begravs på mindre roll. Begravningsplatsens arkitektur är inte så full av symbolik som jag hade väntat mig. Viktigast är platsens avgränsning mot omvärlden och att man får en känsla av att träda in i en annan värld. På begravningsplatsen är det gravarna som står i centrum och möblerar rummet. Det är viktigt att planera med respekt och vördnad för de anhöriga som besöker en grav. Under arbetets gång framkom att man överlag kan tänka sig att dela begravningsplats med andra religioner, men det fi nns en efterfrågan på egna kvarter. Det skapar en känsla av trygghet att känna igen sig i symboler på omgivande gravar. Vissa grupper håller ceremonier på begravningsplatsen och detta underlättas om gravarna ligger samlat. I Borås har man önskemål om fl er gravplatser för människor med olika religionstillhörighet och det fi nns ett område avsatt för att anlägga en ny begravningsplats. Jag har inte haft ett formellt uppdrag i Borås men jag har haft detta område som utgångspunkt i mitt gestaltningsarbete. I Borås skapar jag en ljus plats som domineras av glasbjörk. Mellan träden öppnar sig gläntor som är gravkvarteren. Besökarna ser från sitt eget kvarter till nästa och får en känsla av gemenskap samtidigt som platsen för den egna graven känns hemvan och tryggt Kvarteren är inte i förväg bestämda för en viss religion. De tas i bruk efter hand och planeras i detalj efter de behov och önskemål som gruppen som ska nyttja dem har

Dynamometer power output measurements of piezoelectric actuators

Abstract — Piezoelectric bending actuators are an attractive option for driving microrobots due to their light weight, scalability, ease of integration and high bandwidth. However, the only existing energy or power output measurements for piezoelectric bending actuators have been extrapolated from DC values or unloaded AC values and are most likely overestimates. For microrobot applications such as flapping flight, accurate measures of power density are critical. In this work, to properly measure the energy output of a 10mg piezoelectric actuator, a custom dynamometer is designed and constructed to directly measure the power output at various frequencies and conditions. The dynamometer can simulate a pure resistive load at resonant frequencies from 1 to 100Hz. Due to low internal damping and fracture limits, actuators cannot be run in the matched condition at high fields (> 1 V/µm). Using the device, energy output per cycle at 1.6 V/µm was measured to be a maximum of 19.1 µJ/cycle (232 µm amplitude, 30Hz), giving a delivered energy density per cycle of 1.89J/kg. Internal actuator damping was measured at 1 V/µm to account for an energy loss of only 0.21µJ per cycle (232 µm amplitude, 30Hz). I

JSEL: Jamming Skin Enabled Locomotion

Abstract—A soft, mobile, morphing robot is a desirable platform for traversing rough terrain and navigating into small holes. In this work, a new paradigm in soft robots is presented that utilizes jamming of a granular medium. The concept of activators (as opposed to actuators) is presented to jam and unjam cells that then modulate the direction and amount of work done by a single central actuator. A prototype jamming soft robot utilizing JSEL (Jamming Skin Enabled Locomotion) with external power and control is discussed and both morphing results and mobility (rolling) results are presented. Future directions for the design of a soft, hole traversing robot are discussed, as is the role and promises of jamming as an enabling technology for soft robotics. I

Characterization of the micromechanical flying insect by optical sensing

Abstract — In the following work, we develop a characterization method using miniature fiberoptic position sensors for the Micromechanical Flying Insect (MFI) 1, a centimeter sized micro aerial vehicle being developed at the University of California, Berkeley. Sensing the state of a structure of this scale is challenging due to limited sensor technology and difficulty in constraining the structure. We developed a unique fiberoptic reflection position sensor and associated circuitry that yields a high resolution (approximately 5 µm of linear motion), appropriate scale, and real time method for sensing the state of the MFI. Also included is the development of a clamping technique for the 2 wing, 4 degree of freedom MFI designed to expose actuator surfaces to be sensed while properly grounding the MFI without introducing added compliance or stiffness to the airframe. We include characterization data for a 2 DOF (flapping and rotation for one wing) wing structure, a clamped 4 DOF motor core of theMFI,andonesideofanentire4DOFMFI