On Selecting and Scheduling Assembly Plans Using Constraint Programming

This work presents the application of Constraint Programming to the problem of selecting and sequencing assembly operations. The set of all feasible assembly plans for a single product is represented using an And/Or graph. This representation embodies some of the constraints involved in the planning problem, such as precedence of tasks, and the constraints due to the completion of a correct assembly plan. The work is focused on the selection of tasks and their optimal ordering, taking into account their execution in a generic multi-robot system. In order to include all different constraints of the problem, the And/Or graph representation is extended, so that links between nodes corresponding to assembly tasks are added, taking into account the resource constraints. The resultant problem is mapped to a Constraint Satisfaction Problem (CSP), and is solved using Constraint Programming, a powerful programming paradigm that is increasingly used to model and solve many hard real-life problems

A Pomset-Based Model for Estimating Workcells' Setups in Assembly Sequence Planning

This paper presents a model based on pomsets (partially ordered multisets) for estimating the minimum number of setups in the workcells in Assembly Sequence Planning. This problem is focused through the minimization of the makespan (total assembly time) in a multirobot system. The planning model considers, apart from the durations and resources needed for the assembly tasks, the delays due to the setups in the workcells. An A* algorithm is used to meet the optimal solution. It uses the And/Or graph for the product to assemble, that corresponds to a compressed representation of all feasible assembly plans. Two basic admissible heuristic functions can be defined from relaxed models of the problem, considering the precedence constraints and the use of resources separately. The pomset-based model presented in this paper takes into account the precedence constraints in order to obtain a better estimation for the second heuristic function, so that the performance of the algorithm could be improved

Обзор детекторов гамма-излучения для контроля положения ствола горизонтальной скважины

Представлен обзор детекторов гамма-излучения и принципы их работы. Приведены основные характеристики счетчиков гамма-излучения. Отмечены основные достоинства и недостатки данных устройств. Выбран детектор для регистрации гамма-излучения в процессе горизонтального бурения нефтяных и газовых скважин

Formulation and Search of Assembly Sequence Design Spaces for Efficient Use of Assembly Plant Resources for New Products

Efficient procedures for generation of feasible assembly sequences and effective utilization of available assembly plant resources can greatly reduce the development time and cost of platforms for new product family members. This article presents a method to generate feasible assembly sequences and an approach to select an assembly process that reduces the existing plant modification cost. Assembly sequence design space is combinatorial in nature. Mathematical models to solve the effects of constraints on these spaces and algorithms to efficiently enumerate feasible spaces are explored in this research. Algorithms to search the feasible space to identify assembly process that can reduce the modification cost of the existing assembly plant can help increase utilization of existing resources. A software application that implements the method and algorithms has been developed. The algorithms use the concept of recursive partitioning of set of components to generate assembly sequence space. The assembly processes are then evaluated to determine the process that maximizes resource utilization for new platforms. The application of the proposed approach is demonstrated using automotive underbody front structure family.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline