The dynamic nearest neighbor policy for the multi-vehicle pick-up and delivery problem

In this paper, a dynamic nearest neighbor (DNN) policy is proposed for operating a fleet of vehicles to serve customers, who place calls in a Euclidean service area according to a Poisson process. Each vehicle serves one customer at a time, who has a distinct origin and destination independently and uniformly distributed within the service area. The new DNN policy is a refined version of the nearest neighbor (NN) policy that is well known to perform sub-optimally when the frequency of customer requests is high. The DNN policy maintains geographically closest customer-to-vehicle assignments, due to its ability to divert/re-assign vehicles that may be already en-route to pick up other customers, when another vehicle becomes available or a new customer call arrives. Two other pertinent issues addressed include: the pro-active deployment of the vehicles by anticipating in which regions of the service area future calls are more likely to arise; and, imposition of limits to avoid prohibitively long customer wait times. The paper also presents accurate approximations for all the policies compared. Extensive simulations, some of which are included herein, clearly show the DNN policy to be tangibly superior to the first-comefirst-served (FCFS) and NN policies

WORKSPACE-BASED ARCHITECTURE SELECTION OF A 3-DEGREE- OF-FREEDOM PLANAR PARALLEL MANIPULATOR

ABSTRACT This paper presents the workspace-based architecture selection process and singularity analysis of a high-speed, high-precision three degree-of-freedom (3-DOF) planar parallel manipulator for wirebonding and electronic-component placement applications. A novel concept of manipulator "effective base area" is utilized for selecting the optimal architecture amongst the possible six well-known configurations. Dexterity regions, based on the manipulator requirements, within the reachable workspace have been identified for the selected architecture. Singular configurations of the optimal 3-PRR architecture have also been examined within the reachable workspace. Simulation results for both workspace and singularity analyses are also presented

A Methodology for Multi-Camera Surface-Shape Estimation of Deformable Unknown Objects

A novel methodology is proposed herein to estimate the three-dimensional (3D) surface shape of unknown, markerless deforming objects through a modular multi-camera vision system. The methodology is a generalized formal approach to shape estimation for a priori unknown objects. Accurate shape estimation is accomplished through a robust, adaptive particle filtering process. The estimation process yields a set of surface meshes representing the expected deformation of the target object. The methodology is based on the use of a multi-camera system, with a variable number of cameras, and range of object motions. The numerous simulations and experiments presented herein demonstrate the proposed methodology’s ability to accurately estimate the surface deformation of unknown objects, as well as its robustness to object loss under self-occlusion, and varying motion dynamics

Discrete Event And Hybrid Systems In Robotics And Automation

Discrete Event and Hybrid Systems modeling has been used extensively in automation, robotics, and manufacturing appilications. Different frameworks for dynamic supervisory controllers are used in flexible manufacturing systems (FMS) and automated processes. This article presents an overview of some existing strategies that are used to control systems in real-time based on sensory data.http://ieeexplore.ieee.org.libproxy.bridgeport.edu:9000/stamp/stamp.jsp?tp=&arnumber=59164

Hay Azulay A Multi-Tier Design Methodology for Reconfigurable Milling Machines

Reconfigurable Machine Tools (RMTs) have been developed in response to agile flexible manufacturing demands. Current design methodologies for RMTs support modular reconfigurability in which a machine configuration is assembled for a given part. In this paper, on the other hand, reconfigurability relies on redundancy, namely, a desired RMT configuration is obtained through topological reconfiguration by locking/unlocking degrees-of-freedom (dof). Thus, in order to design a Redundant Reconfigurable Machine Tool (RRMT) with all of its dof already included, a new multi-tier optimization based design methodology was developed. The design is formulated for the efficient selection of the best architecture from a set of serial/parallel/hybrid solutions, while considering the redundant reconfigurability effect on performance. The viability of the methodology is demonstrated herein via a design test case of a Parallel Kinematic Mechanism (PKM)-based Redundant Reconfigurable meso-Milling Machine Tool (RRmMT) that can attain high stiffness at the high feed-rate required in meso-milling