GRAVITY–OPERATED IMPACT FEEDER DYNAMICS

This paper deals with the dynamics of rigid body that collide with a rigid surface; such motion with impact of bodies takes place in the gravity operated impact feeders. Feeders are mechanisms of the single- peace feeding for the forced moving of the oriented workpieces. In this work the vertical gravity-impact feeder for moving of the prismatic or plane details is presented. The parts move on inclined guiding plates, free fall and collide with the down plates, the impact phenomena may be used both for decreasing of velocity and for the orientation of the tracking workpieces (lateral reversing). System of equations of plane motion of detail, including stages of sliding on the slope guideway, free flight, impact and motion to the next guideway, are written down. System of equations is solved numerically with help of MathCAD program

Novi mehanizam za pasivno-dinamičnu manipulaciju objektom duž zakrivljenog puta

Object manipulation is a basic task in robotics and automation. Active manipulation by grasp is conventional approach in object manipulation. However, in many cases, grasp-less manipulation can be beneficial in terms of cost, minimalism and extension of workspace. On the other hand passive mechanisms are advantageous from the energy saving viewpoint. In this paper we combine these ideas to develop a dynamic passive object manipulation mechanism to achieve manipulation in more than one dimension and simultaneously change position and orientation of the object. In developed mechanism the manipulation platform is a simple inclined surface. The object is composed of two wheels with different radiuses and an axle connecting the wheels to each other. The object moves passively along a circular path on the platform. Kinematic equations of the motion are devised, dynamic analyses are performed and no-slippage conditions are extracted. Modelling in CATIA and simulations in MSC.ADAMS are performed and experimental set up is built to verify the analysis.Manipulacija objektom je osnovni zadatak u robotici i automatici.Aktivna manipulacija hvatom predstavlja konvencionalan prostup manipulaciji objektom. Ipak, u mnogim slučajevima, manipulacija objektom bez hvata može biti korisna u smislu troškova, minimalizma i proširenja radnom prostora.S druge strane, pasivni mehanizmi posjeduju prednosti iz perspektive uštede energije. U ovom radu mi kombiniramo ove ideje kako bismo razvili dinamično-pasivni mehanizam za manipulaciju objektom u svrhu postizanja manipulacije u više od jedne dimenzije i simultano mijenjali poziciju i orijentaciju objekta. U razvijenom mehanizmu platforma za manipulaciju sastoji se od jednostavne nagnute plohe. Objekt se sastoji od dvaju kotača različitih radijusa i jedne osi koja spaja kotače. Objekt se kreće pasivno duž zakrivljenog puta na platformi.Postaljene su jednadžbe kinematike gibanja, te je analizirana dinamika, dok je klizanje zanemareno. U svrhu verifikacije analize izrađen je model eksperimentalnog postava u CATIA-i te su provedene simulacije korištenjem MSC.ADAMS alata

Particle Computation: Complexity, Algorithms, and Logic

We investigate algorithmic control of a large swarm of mobile particles (such as robots, sensors, or building material) that move in a 2D workspace using a global input signal (such as gravity or a magnetic field). We show that a maze of obstacles to the environment can be used to create complex systems. We provide a wide range of results for a wide range of questions. These can be subdivided into external algorithmic problems, in which particle configurations serve as input for computations that are performed elsewhere, and internal logic problems, in which the particle configurations themselves are used for carrying out computations. For external algorithms, we give both negative and positive results. If we are given a set of stationary obstacles, we prove that it is NP-hard to decide whether a given initial configuration of unit-sized particles can be transformed into a desired target configuration. Moreover, we show that finding a control sequence of minimum length is PSPACE-complete. We also work on the inverse problem, providing constructive algorithms to design workspaces that efficiently implement arbitrary permutations between different configurations. For internal logic, we investigate how arbitrary computations can be implemented. We demonstrate how to encode dual-rail logic to build a universal logic gate that concurrently evaluates and, nand, nor, and or operations. Using many of these gates and appropriate interconnects, we can evaluate any logical expression. However, we establish that simulating the full range of complex interactions present in arbitrary digital circuits encounters a fundamental difficulty: a fan-out gate cannot be generated. We resolve this missing component with the help of 2x1 particles, which can create fan-out gates that produce multiple copies of the inputs. Using these gates we provide rules for replicating arbitrary digital circuits.Comment: 27 pages, 19 figures, full version that combines three previous conference article

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

Algorithms for Robot Coverage Under Movement and Sensing Constraints

This thesis explores the problem of generating coverage paths—that is, paths that pass within some sensor footprint of every point in an environment—for mobile robots. It both considers models for which navigation is a solved problem but motions are constrained, as well for models in which navigation must be considered along with coverage planning because of the robot’s unreliable sensing and movements. The motion constraint we adopt for the former is a common constraint, that of a Dubins vehicle. We extend previous work that solves this coverage problem as a traveling salesman problem (TSP) by introducing a practical heuristic algorithm to reduce runtime while maintaining near-optimal path length. Furthermore, we show that generating an optimal coverage path is NP-hard by reducing from the Exact Cover problem, which provides justification for our algorithm’s conversion of Dubins coverage instances to TSP instances. Extensive experiments demonstrate that the algorithm does indeed produce path lengths comparable to optimal in significantly less time. In the second model, we consider the problem of coverage planning for a particular type of very simple mobile robot. The robot must be able to translate in a commanded direction (specified in a global reference frame), with bounded error on the motion direction, until reaching the environment boundary. The objective, for a given environment map, is to generate a sequence of motions that is guaranteed to cover as large a portion of that environment as possible, in spite of the severe limits on the robot’s sensing and actuation abilities. We show how to model the knowledge available to this kind of robot about its own position within the environment, show how to compute the region whose coverage can be guaranteed for a given plan, and characterize regions whose coverage cannot be guaranteed by any plan. We also describe an algorithm that generates coverage plans for this robot, based on a search across a specially-constructed graph. Simulation results demonstrate the effectiveness of the approach

Parts Feeding on a Conveyor with a One Joint Robot

. This paper explores a method of manipulating a planar rigid part on a conveyor belt using a robot with just one joint. This approach has the potential of offering a simple and flexible method for feeding parts in industrial automation applications. In this paper we develop a model of this system and of a variation which requires no sensing. We have been able to characterize these systems and to prove that they can serve as parts feeding devices for planar polygonal parts. We present the planners for these systems and describe our implementations. Key Words. Robotics, Manipulation, Mechanics, Planning, Minimalism, Automation, Manufacturing, Parts feeding. 1. Introduction. The most straightforward approach to planar manipulation is to use a rigid grasp and a robot with at least three joints, corresponding to the three motion freedoms of a planar rigid part, but three joints are not really necessary to manipulate a part in the plane. In this paper we achieve effective control of all t..

Parts Feeding on a Conveyor with a One Joint Robot

This paper explores a method of manipulating a planar rigid part on a conveyor belt using a robot with just one joint. This approach has the potential of offering a simple and flexible method for feeding parts in industrial automation applications. In this paper we develop a model of this system and of a variation which requires no sensing. We have been able to characterize these systems and to prove that they can serve as parts feeding devices for planar polygonal parts. We present the planners for these systems and describe our implementations