217 research outputs found

    Orienting polyhedral parts by pushing

    Get PDF
    A common task in automated manufacturing processes is to orient parts prior to assembly. We consider sensorless orientation of an asymmetric polyhedral part by a sequence of push actions, and show that is it possible to move any such part from an unknown initial orientation into a known final orientation if these actions are performed by a jaw consisting of two orthogonal planes. We also show how to compute an orienting sequence of push actions.We propose a three-dimensional generalization of conveyor belts with fences consisting of a sequence of tilted plates with curved tips; each of the plates contains a sequence of fences. We show that it is possible to compute a set-up of plates and fences for any given asymmetric polyhedral part such that the part gets oriented on its descent along plates and fences

    Teleoperation in the Presence of Communication Delays

    Get PDF
    Modern industrial processes, public service needs, and research interests have established a clear need to perform work remotely [12][4]. Teleoperators were developed with the advent of nuclear industry in the mid 1940\u27s and have been since used extensively to perform work in hazardous environments (nuclear, chemical), undersea (resource exploration, waste management, pollution monitoring), and in the outer space (sample acquisition, satellite deployment/repair). Sophisticated systems have been designed and built to meet these needs, providing the human operator with high bandwidth and high fidelity visual and kinesthetic feedback information about the task in progress [22] [32] [16] [6]

    A two-phase gripper to reorient and grasp

    Get PDF
    This paper introduces the design of novel two-phase fingers to passively reorient objects while picking them up. Two-phase refers to a change in the finger-object contact geometry, from a free spinning point contact to a firm multipoint contact, as the gripping force increases. We exploit the two phases to passively reorient prismatic objects from a horizontal resting pose to an upright secure grasp. This problem is particularly relevant to industrial assembly applications where parts often are presented lying on trays or conveyor belts and need to be assembled vertically. Each two-phase finger is composed of a small hard contact point attached to an elastic strip mounted over a V-groove cavity. When grasped between two parallel fingers with low gripping force, the object pivots about the axis between the contact points on the strips, and aligns upright with gravity. A subsequent increase in the gripping force makes the elastic strips recede into the cavities letting the part seat in the V-grooves to secure the grasp. The design is compatible with any type of parallel-jaw gripper, and can be reconfigured to specific objects by changing the geometry of the cavity. The two-phase gripper provides robots with the capability to accurately position and manipulate parts, reducing the need for dedicated part feeders or time-demanding regrasp procedures.National Science Foundation (U.S.). National Robotics Initiative (NSF-IIS-1427050

    Model Based Teleoperation to Eliminate Feedback Delay NSF Grant BCS89-01352 First Report

    Get PDF
    We are conducting research in the area of teleoperation with feedback delay. Delay occurs with earth-based teleoperation in space and with surface-based teleoperation with untethered submersibles when acoustic communication links are involved. the delay in obtaining position and force feedback from remote slave arms makes teleoperation extremely difficult. We are proposing a novel combination of graphics and manipulator programming to solve the problem by interfacing a teleoperator master arm to a graphics based simulator of the remote environment coupled with a robot manipulator at the remote, delayed site. the operator\u27s actions will be monitored to provide both kinesthetic and visual feedback and to generate symbolic motion commands to the remote slave. the slave robot will then execute these symbolic commands delayed in time. While much of a task will proceed error free, when an error does occur the slave system will transmit data back to the master and the master environment will be reset to the error state

    Master index of Volumes 21–30

    Get PDF

    Design, Performance Prediction and Validation of a Seed Orienting Corn Planter

    Get PDF
    Investigations into active control of corn canopy architecture through manipulation of seed orientation at planting have shown that specific seed orientations produce highly aligned leaf azimuths. Data obtained from hand planted field trials with across-row oriented leaves show that such canopies intercept more light and ultimately produce higher yields. This study was conducted to investigate the feasibility of mechanized seed orientation through the concept of part orientation by pushing. 3D-scans of 15 "medium flat" kernels of the hybrids DKC-6342, DKC-6346, P0902HR and P1162HR have been computationally analyzed to determine stable seed orientations when subjected to pushing. These predicted results were compared to data obtained in bench tests. The concept was then refined and integrated into a prototype planter based on a standard off-the-shelf row unit. The prototype was first tested in a soil bin at laboratory conditions and then in the field. Because field tests do not allow measurement of seed orientations directly greenhouse studies of the relationship between seed orientation and seed leaf azimuth distributions were conducted to assess the feasibility of an indirect post-emergence performance measure. The computational model was able to predict seed orientation by pushing very accurately. The analysis and subsequent bench unit and prototype tests revealed that orientation performance is dependent on seed shape with the kernels of DKC-6342 being the most and those of P1162HR the least suitable. Soil bin and field data confirmed that at least parity between seed and ground velocity must be achieved in order to maintain orientation during transition from the orientation mechanism to the ground. The greenhouse studies led to the conclusion that seed-to-leaf azimuth distributions can be described by von Mises models. Due to the specific design of the orienter, the shape of the kernels, and the observed seed-to-leaf azimuth properties the measureable seed leaf azimuth distribution in the field is expected to be a von Mises mixture containing four modes. The complexity of such a mixture inhibits the accurate, indirect determination of seed orientation performance in the field.Biosystems & Agricultural Engineerin

    From 3D Models to 3D Prints: an Overview of the Processing Pipeline

    Get PDF
    Due to the wide diffusion of 3D printing technologies, geometric algorithms for Additive Manufacturing are being invented at an impressive speed. Each single step, in particular along the Process Planning pipeline, can now count on dozens of methods that prepare the 3D model for fabrication, while analysing and optimizing geometry and machine instructions for various objectives. This report provides a classification of this huge state of the art, and elicits the relation between each single algorithm and a list of desirable objectives during Process Planning. The objectives themselves are listed and discussed, along with possible needs for tradeoffs. Additive Manufacturing technologies are broadly categorized to explicitly relate classes of devices and supported features. Finally, this report offers an analysis of the state of the art while discussing open and challenging problems from both an academic and an industrial perspective.Comment: European Union (EU); Horizon 2020; H2020-FoF-2015; RIA - Research and Innovation action; Grant agreement N. 68044
    • …
    corecore