Orienting polyhedral parts by pushing

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

A model for adapting 3D graphics based on scalable coding, real-time simplification and remote rendering

Most current multiplayer 3D games can only be played on dedicated platforms, requiring specifically designed content and communication over a predefined network. To overcome these limitations, the OLGA (On-Line GAming) consortium has devised a framework to develop distributive, multiplayer 3D games. Scalability at the level of content, platforms and networks is exploited to achieve the best trade-offs between complexity and quality

Geometric design of part feeders

This thesis presents solutions for problems derived from industrial assembly and robotic manipulation. The basic tasks in a factory are manufacturing the parts, and combining them into the desired product. In automating these tasks, we want to use robot manipulators that require little or no human intervention. We explore devices that deliver parts in a uniform orientation to robots. Such a device is called a partfeeder. Part feeders are used to improve the efficiency in an industrial assembly line: robots to which the parts are fed in a uniform orientation can easily process these parts without having to sense their initial orientations. In practice, the problem of part feeding is usually solved using trial-and-error approaches which are time consuming and error prone. We show how to systematically design part feeders using techniques from computational geometry. We consider four different feeders. The first feeder consists of a sequence of fences which are mounted across a conveyor belt. The fences brush the part as it travels down the belt thus reorienting it. The second feeder is a pulling finger which applies a sequence of pull operations that reorients flat parts with elevated edges. The third feeder deals with three-dimensional parts. It is a sequence of (tilted) plates with fences which reorients a three-dimensional polyhedral part as it travels down the plates. The fourth feeder in this thesis is the vibratory bowl feeder. This thesis gives insight into the geometrical nature of part feeding problems. The results have implications for practical design of part feeding devices, and experimental results can be used as input for future research in geometric feeding

Pin Design for Part Feeding = Dept. of Industrial Eng.

Abstract-- We consider a sensorless approach to feeding parts on a conveyor belt using pins (rigid barriers) to topple parts into desired orientations. Given the n-sided 2D convex projection of an extruded polygonal part, its center of mass (COM), and coefficients of friction, we develop an O(n 2) algorithm to compute the toppling graph, a new data struc-ture that represents the mechanics of toppling including rolling and jamming. The top-pling graph can be used to identify critical pin heights that permit toppling. We compare pin heights predicted by the graph with physical experiments, and give a complete O(n 3n) algorithm for designing pin sequences

Dynamic Motion Planning in Low Obstacle Density Environments

A fundamental task for an autonomous robot is to plan its own motions. Exact approaches to the solution of this motion planning problem suffer from high worst-case running times. The weak and realistic low obstacle density (L.O.D.) assumption results in linear complexity in the number of obstacles of the free space [11]. In this paper we address the dynamic version of the motion planning problem in which a robot moves among moving polygonal obstacles. The obstacles are assumed to move along constant complexity polylines, and to respect the low density property at any given time. We will show that in this situation a cell decomposition of the free space of size O(n 2 ff(n) log 2 n) can be computed in O(n 2 ff(n) log 2 n) time. The dynamic motion planning problem is then solved in O(n 2 ff(n) log 3 n) time. We also show that these results are close to optimal. Keywords: Motion planning, low obstacle density, moving obstacles, cell decomposition. 1 Introduction Robot motion..

OLGA: On-Line GAming over Heterogeneous Platforms Thanks to Standard Scalable Content

Most current multi-player 3D games can only be played on a single dedicated platform such as PCs, video-consoles, or (very recently) cell-phones, requiring specifically designed content and inter-terminal communication over a predefined network. To overcome these limitations, the OLGA (On-Line GAming) consortium has devised a framework to develop real distributive, multi-player 3D games where scalability at the level of content, platforms and networks is exploited to achieve the best complexity vs. quality and load-balancing trade-offs given the distributive resources available over the end-to-end delivery chain. Additionally, standardized content representation and compression formats (XML, MPEG-4, JPEG 2000) are used in OLGA’s framework, enabling easy deployment over existing infrastructure, while keeping hooks to well-established practices in the game industry

Computing Fence Designs for Orienting Parts

A common task in automated manufacturing processes is to orient parts prior to assembly. We consider sensorless orientation of a polygonal part by a sequence of fences. We show that any polygonal part can be oriented by a sequence of fences placed along a conveyor belt, thereby settling a conjecture by Wiegley et al. [17], and present the first polynomial-time algorithm to compute the shortest such sequence. The algorithm is easy to implement and runs in time O(n 3 log n), where n is the number of vertices of the part. 1 Introduction Many automated manufacturing processes require parts to be oriented prior to assembly. A part feeder takes in a stream of identical parts in arbitrary orientations and outputs them in a uniform orientation. Part feeders often use data obtained from some kind of sensing device to accomplish their task. We consider the problem of sensorless orientation of parts, in which the initial pose of the part is assumed to be unknown. In sensorless manipulati..