Assembly Planning System Research Articles

Автоматизоване планування послідовності складання

Modern industrial production requires the improvement of assembly processes, and thus increase the level of automated intelligent sequence planning. Therefore, researches in the field of automation of the sequence of assembly of products in industries are relevant at this time. In today's world there is a need to develop complex, accurate products. Problems are created in industries due to the reduction of the life cycle of products. There is a need to study the problem of assembly planning to achieve the goal of practical implementation and standardization of assembly plans. Creating graphs of the addition process is one of the problems. The assembly planning system can reduce human intervention in the process and reduce computational effort. The finished assembly contains many components that can be assembled using many sequences. A review of the methods from the literature showed that although these methods increase the automation level, they still cannot be applied to actual production because they do not take into account the experience and knowledge that can play a major role in planning and are of great value. Assembly planning, relationship charts, priority charts. Improving the assembly planning system to create a communication schedule and an assembly priority schedule was proposed. The advanced system will be used to generate possible assembly sequences with subassembly identification. A system has been developed to create alternative possible assembly sequences that can be used by component part / product designers in the early stages. A system capable of generating assembly sequences for simultaneous assembly of multiple parts has been proposed. Conclusions and work results can be applied used and improved for more productive product development by designers in the early stages and faster assembly of products in enterprises. The paper did not consider practical limitations (gravity) and irreversible assembly operations, such as permanent fastening, welding etc. Кey words: assembly, blocking graph, relation graph, sequence

CAD와 BOM 통합 데이터베이스 기반 로봇 조립 계획 시스템 아키텍처 개발

This study proposes a system architecture based on integrated Computer-Aided Design (CAD) and Bill of Material (BOM) databases for a robot assembly planning system. The architecture consists of CAD, Product Data Management (PDM) and robot assembly planning applications based on CAD, BOM and robot databases. It manages shape and product structure data from 3D CAD files as data objects in CAD and BOM databases, and stores general robot assembly planning data from robot teaching results as robot path objects in the robot database. Robot engineers create robot assembly plans using a process BOM that incorporates data from the CAD, BOM and robot databases. Throughout the generation of robot assembly plans, the architecture uses the shape data of participating parts in CAD database to automatically calculate the positions of robot end-effectors. This paper describes the implementation of applications and databases in the architecture using FreeCAD, MariaDB and Apache Tomcat Web application server. It also outlines cases of experimental robot assembly planning using the implemented planning systems and robot arms at laboratory level.

Agile Montage*/Agile assembly – Assembly planning and assembly system as integral elements of factory planning

Produzierende Unternehmen intensivieren aufgrund zunehmend volatiler Kundenbedürfnisse die Anwendung agiler Produktentwicklungsansätze. Ziel des Beitrags ist die Einführung eines Konzepts zur Befähigung dieser dynamischen Produktentwicklung in der Montage. Der integrative Lösungsansatz basiert auf der wirtschaftlichen Optimierung des Agilitätsgrades von Montagesystemen sowie dem selektiven Einsatz agiler Methoden in der traditionell plangetriebenen Montageplanung als Teil der Fabrikplanung.   To meet more volatile customer needs, manufacturing companies increasingly make use of agile product development approaches. This article aims to introduce a concept to enable for dynamic product development in assembly. This integrative solution approach is based on the economic optimization of the degree of agility of assembly systems and on the selective use of agile methods in traditional, plan-driven assembly planning as part of factory planning.

Optimum Assembly Sequence Planning System Using Discrete Artificial Bee Colony Algorithm

Assembly refers both to the process of combining parts to create a structure and to the product resulting therefrom. The complexity of this process increases with the number of pieces in the assembly. This paper presents the assembly planning system design (APSD) program, a computer program developed based on a matrix-based approach and the discrete artificial bee colony (DABC) algorithm, which determines the optimum assembly sequence among numerous feasible assembly sequences (FAS). Specifically, the assembly sequences of three-dimensional (3D) parts prepared in the computer-aided design (CAD) software AutoCAD are first coded using the matrix-based methodology and the resulting FAS are assessed and the optimum assembly sequence is selected according to the assembly time optimisation criterion using DABC. The results of comparison of the performance of the proposed method with other methods proposed in the literature verify its superiority in finding the sequence with the lowest overall time. Further, examination of the results of application of APSD to assemblies consisting of parts in different numbers and shapes shows that it can select the optimum sequence from among hundreds of FAS.

Hierarchical exploded view generation based on recursive assembly sequence planning

A method for automatic generation of hierarchical exploded view for complex products based on recursive search of multi-level assembly sequences is proposed. Two interference detection methods based on extruding bounding face and feature face are presented to narrow the detection range and quickly acquire the extended interference matrix, which is used to solve the problem that some components have to be assembled in oblique directions. The method of assembly reconstruction is developed to define a subassembly and edit an assembly tree. The method of merging interference matrix is proposed to flexibly generate hierarchical assembly relation matrices and avoid repetitive interference detection. The whole assembly sequence planning task is subdivided into the subtasks of the customized levels so that the complexity of a large-scale sequence planning is reduced. The multi-rule screening algorithm is applied to each subtask, where interference matrix-based geometric feasibility is taken as the precondition and parallelism, continuity, stability, and directionality as the screening criterions to circularly construct a satisfactory sequence. The recursive explosion algorithm iterates depth-first search for hierarchical assembly sequences and calculates the accumulative bounding box of the exploded components to decide the position of the exploding component. The generated exploded view is uniform in interval, compact in structure and clearly hierarchical, based on which hierarchical assembly trace lines and explosion simulation can be easily implemented. An assembly planning system “AutoAssem” is developed on UG NX, and a gear reducer and the big parts of a car are taken as examples to verify the effectiveness of the methods.

Integrated assembly and motion planning using regrasp graphs.

This paper presents an integrated assembly and motion planning system to recursively find the assembly sequence and motions to assemble two objects with the help of a horizontal surface as the supporting fixture. The system is implemented in both assembly level and motion level. In the assembly level, the system checks all combinations of the assembly sequences and gets a set of candidates. Then, for each candidate assembly sequence, the system incrementally builds regrasp graphs and performs recursive search to find a pick-and-place motion in the motion level to manipulate the base object as well as to assemble the other object to the base. The system integrates the candidate assembly sequences computed in the assembly level incrementally and recursively with graph searching and motion planning in the motion level and plans the assembly sequences and motions integratedly for assembly tasks. Both simulation and real-world experiments are performed to demonstrate the efficacy of the integrated planning system.

Integration of CAD models with product assembly planning in a Web-based 3D visualized environment

Product assembly planning plays an important role in the product life cycle management. Product assembly planning consists of the product representation, assembly sequence generation, and the sequence optimization. An efficient assembly planning depends on the integration of CAD models with product assembly analysis. However, existing product modeling systems are separated from the product assembly planning. 3D CAD models cannot be directly used by most of the product assembly planning systems. The data extraction from CAD models becomes a critical process in the integrated product development system. This paper presents an integration method of CAD models with product assembly planning. Product data are extracted from product CAD-VRML models and stored in MySQL database. The extracted data are regrouped for product assembly reasoning and 3D visualization. The 3D animation is developed to visually validate the generated assembly plan. The product assembly process is simulated by manipulating the geometry using VRML external authoring interface.

조선 산업에서 프로세스 마이닝을 이용한 블록 조립 프로세스의 계획 및 실적 비교 분석

This paper proposes a method to compare planned processes with actual processes of bock assembly operations in shipbuilding industry. Process models can be discovered using the process mining techniques both for planned and actual log data. The comparison between planned and actual process is focused in this paper. The analysis procedure consists of five steps : 1) data pre-processing, 2) definition of analysis level, 3) clustering of assembly bocks, 4) discovery of process model per cluster, and 5) comparison between planned and actual processes per cluster. In step 5, it is proposed to compare those processes by the several perspectives such as process model, task, process instance and fitness. For each perspective, we also defined comparison factors. Especially, in the fitness perspective, cross fitness is proposed and analyzed by the quantity of fitness between the discovered process model by own data and the other data(for example, the fitness of planned model to actual data, and the fitness of actual model to planned data). The effectiveness of the proposed methods was verified in a case study using planned data of block assembly planning system (BAPS) and actual data generated from block assembly monitoring system (BAMS) of a top ranked shipbuilding company in Korea.

Assembly planning and evaluation in an augmented reality environment

Assembly planning is very critical in the product design process. Previously, computer-assisted assembly planning is mostly conducted in either an automated or interactive manner. Automated approaches can only be applied to products with simple component configurations, whereas extensive user input in the tedious form of answering questions is required for interactive approaches. Both kinds of approaches do not address issues related to human factors and ergonomics, which cannot be ignored in assembly planning especially in manual assembly. Using augmented reality technologies, an intuitive and efficient approach is proposed for manual assembly planning and evaluation by combining the potential strengths of the two kinds of approach. An AR-assisted assembly planning and evaluation system has been developed to implement the proposed methodology with the use of a 3D bare-hand interaction (3DBHI) tool. After loading all the parts of an assembly into the proposed system, assembly modelling is first completed through assembly geometrical constraint recognition and assembly location refinement with the use of the proposed 3DBHI tool. By analysing the disassembly process, precedence constraints are captured and used to search for feasible assembly sequences from all possible sequences, which are generated using an existing method. Finally, practical or good sequences are selected from the feasible sequences by exploiting an assembly index based on objective evaluation. A case study is conducted to demonstrate the application of the methodology and system.

Assembly Sequence Planning Based on Max-Min Ant Colony System

An assembly sequence planning (ASP) method that combined the advantages of ant colony system (ACS) and Max-Min ant system (MMAS) is proposed. To identify the best sequence easily, five optimization criterions are automatically quantified, including reorientation, parallelism, continuity, stability and auxiliary stroke, and then integrated into the multi-objective heuristic and fitness functions of ant colony optimization (ACO). To improve the search capability for the global-best sequence, several measures are presented from aspects of determining number of ant, max-min pheromone limits, performance appraisal for initial components allocation and the group method for same components. The ASP algorithm based on Max-Min ant colony system (MMACS) is proposed. An assembly planning system AutoAssem is developed based on Siemens NX platform, and the actual effectiveness of each optimization measure is testified through case study of a valve.

A max–min ant colony system for assembly sequence planning

An improved ant colony optimization (ACO)-based assembly sequence planning (ASP) method for complex products that combines the advantages of ant colony system (ACS) and max–min ant system (MMAS) and integrates some optimization measures is proposed. The optimization criteria, assembly information models, and components number in case study that reported in the literatures of ACO-based ASP during the past 10 years are reviewed and compared. To reduce tedious manual input of parameters and identify the best sequence easily, the optimization criteria such as directionality, parallelism, continuity, stability, and auxiliary stroke are automatically quantified and integrated into the multi-objective heuristic and fitness functions. On the precondition of geometric feasibility based on interference matrix, several strategies of ACS and MMAS are combined in a max–min ant colony system (MMACS) to improve the convergence speed and sequence quality. Several optimization measures are integrated into the system, among which the performance appraisal method transfers the computing resource from the worst ant to the better one, and the group method makes up the deficiency of solely depending on heuristic searching for all parallel parts in each group. An assembly planning system “AutoAssem” is developed based on Siemens NX, and the effectiveness of each optimization measure is testified through case study. Compared with the methods of priority rules screening, genetic algorithm, and particle swarm optimization, MMACS is verified to have superiority in efficiency and sequence performance.

AutoAssem: An Automated Assembly Planning System for Complex Products

To automate assembly planning for complex products such as aircraft components, an assembly planning and simulation system called AutoAssem has been developed. In this paper, its system architecture is presented; the main components and the key technologies in each component are discussed. The core functions of the system that have been focused include Digital Assembly Modeling, Assembly Sequence Planning (ASP), Path Planning, Visualization, and Simulation. In contrast to existing assembly planning systems, one of the novelties of the system is it allows the assembly plans be automatically generated from a CAD assembly model with minimal manual interventions. Within the system, new methodologies have been developed to: (i) create Assembly Relationship Matrices; (ii) plan assembly sequences; (iii) generate assembly paths; and (iv) visualize and simulate assembly plans. To illustrate the application of the system, the assembly of a worm gear reducer is used as an example throughout this paper for demonstration purpose. AutoAssem has been successfully applied to virtual assembly design for various complex products so far.

Key Performance Indicators for the Impact of Cognitive Assembly Planning on Ramp-Up Process

Within the ramp-up phase of highly automated assembly systems, the planning effort forms a large part of production costs. Due to shortening product lifecycles, changing customer demands, and therefore an increasing number of ramp-up processes, these costs even rise. So assembly systems should reduce these efforts and simultaneously be flexible for quick adaption to changes in products and their variants. A cognitive interaction system in the field of assembly planning systems is developed within the Cluster of Excellence “Integrative production technology for high-wage countries” at RWTH Aachen University which integrates several cognitive capabilities according to human cognition. This approach combines the advantages of automation with the flexibility of humans. In this paper the main principles of the system's core component—the cognitive control unit—are presented to underline its advantages with respect to traditional assembly systems. Based on this, the actual innovation of this paper is the development of key performance indicators. These refer to the ramp-up process as a main objective of such a system is to minimize the planning effort during ramp-up. The KPIs are also designed to show the impact on the main idea of the Cluster of Excellence in resolving the so-called Polylemma of Production.

Human knowledge acquisition from 3D interaction in virtual environments

Recently, virtual environment (VE) based design and planning, which is a kind of interaction intensive computing, has shown great potential. Most users of such systems are specialists or technicians and their 3D interactions with the system embed a great deal of knowledge and skills. Thus, how to integrate human knowledge and skills into VE is a great challenge to researchers in the human computer interaction field. This paper proposes a method for acquiring user knowledge from VE. The main ideas and work include, abstracting the interactive process and formalizing the interactive semantics, as well as providing a semantic model of an interactive information repository, from which user interactive processes can be retrieved and all kinds of application logics can be established. A virtual assembly planning system is introduced as an example of a practical application of this method. Experiments show that the related models can well capture user knowledge and retrieve the interaction process.

Method for Determination of Geometric Dismountability Based on Extended Interference Matrix

Geometric dismountability(GD) of component is the premise for assembly sequence planning based on "acquire assembly by disassembly",while interference matrix is an essential assembly relation model for determination of GD.To solve the problem of GD determination in the directions not parallel to the standard orthogonal coordinate axes,extended interference matrix(EIM) is proposed,whose structure is extended to directions of local coordinate axes of each component.To facilitate analysis of GD of component with multidirectional disassembly path,turning interference matrix(TIM) is proposed,whose structure is compact enough to describe the complete interference information from the turning point.Several methods for generating EIM and TIM rapidly and automatically are presented,including precise stepping-detection,coarse detection and accelerating detection based on bounding-box.The method for refraining static hard-interference automatically is also studied.A more comprehensive algorithm for determining GD based on EIM and TIM is then presented.An assembly planning system "AutoAssem" is developed based on UG NX platform,with the examples illustrating the effectiveness of each interference detection measures.EIM and TIM are testified to enrich the variety and variability of disassembly directions,which provide GD determination for complex production with great commonality,and provide subsequent sequence planning algorithms with effective foundation.

Automatic generation of robot and manual assembly plans using octrees

PurposeThis paper aims to investigate automatic assembly planning for robot and manual assembly.Design/methodology/approachThe octree decomposition technique is applied to approximate a computer‐aided design model with an octree representation which is then used to generate robot and manual assembly plans. An assembly planning system able to generate assembly plans was developed to build these prototype models.FindingsOctree decomposition is an effective assembly planning tool. Assembly plans can automatically be generated for robot and manual assembly using octree models.Research limitations/implicationsOne disadvantage of the octree decomposition technique is that it approximates a part model with cubes instead of using the actual model. This limits its use and applications when complex assemblies must be planned, but in the context of prototyping can allow a rough component to be formed which can later be finished by hand.Practical implicationsAssembly plans can be generated using octree decomposition, however, new algorithms must be developed to overcome its limitations.Originality/valueThis paper has proved that the octree decomposition technique is an effective assembly planning tool. As a result, an assembly planning system has been developed. Assembly plans for automatic and manual assembly can be generated automatically by the proposed system, which is a novelty since there are no fully automatic assembly planning systems for manual assembly reported in the literature.

Assembly planning based on semantic modeling approach

There are still some challenges for the research of assembly planning. One of the reasons is the weakness in effective description of assembly knowledge and information. An assembly semantic modeling approach is presented. Product (assembly) information is described by a three-level semantic abstraction (Concept/Function Level, Structure Level and Part/Feature Level). Semantic object is an abstract description of special product information, in particularly, for assembly relevant information in this proposed study. And by a multi-mapping mechanism supported by Semantic Interpreter and Semantic Dictionary, these objects could retrieve relevant technologic information, e.g. assembly design intention, basic function, assembly hierarchical structure, assembly relations and assembly knowledge, etc., from resource bank. Based on this approach, an interactive assembly planning system is developed. Product semantic information model could offer much useful information for designer to finish the assembly (process) design and make determination in that process. Therefore, complex and low efficient computation in the design (or planning) process could be avoided.

Optimising assembly planning based on virtual reality and bionic algorithm

Virtual assembly, as a typical application of Virtual Reality (VR), provides an efficient tool to optimise assembly planning and evaluation. In this paper, a VR-based Assembly Planning and Training System (VR-APTS) is introduced. Using a Computer-Aided Design (CAD) assembly model as input, the system can output one or several good assembly sequences with the application of an intelligent bionic algorithm. Key techniques in the development of VR-APTS are discussed. A novel information decomposition and transformation method is put forward to transform data from CAD to VR, and a geometric constraint-based virtual environment is set up to support interactive assembly planning and evaluation. First, an initial optimal assembly sequence is generated by virtual disassembly and ant colony optimisation algorithm. Then, this initial sequence is evaluated by virtual assembly simulation, a more practical and optimal assembly sequence is replaned. This is an iterative process until the best assembly sequence is obtained. An application case is studied to demonstrate the basic advantages of the system for assembly planning and training.

A pragmatic system to support interactive assembly planning and training in an immersive virtual environment (I-VAPTS)

Assembly planning for complex products is a difficult task requiring both intensive knowledge and experience. Computer aided assembly planning (CAAP) systems have been the subject of considerable research in recent years without achieving a wide application in manufacturing industry. In this paper an alternative approach to the generation of an optimal assembly planning scheme is presented based on the adoption of immersive virtual reality. A product is assembled from CAD models by providing a CAD interface to transfer assembly constraint information from the CAD system to a virtual environment. In the virtual environment an efficient dynamic recognition and management method based on surface geometry is employed, and a process-oriented assembly task model is established to support interactive assembly planning and evaluation. The system is implemented using an object oriented methodology, and has been successfully applied to train and guide the assembly workers in a pump assembly process.

An automated system for the assembly of octree models

This paper presents a novel approach for rapid prototyping based on the octree decomposition of 3D geometric models. The proposed method, referred as OcBlox, integrates an octree modeller, an assembly planning system, and a robotic assembly cell into an integrated system that builds approximate prototypes directly from 3D model data. Given an exact 3D model this system generates an octree decomposition of it, which approximates the shape cubic units referred as “Blox”. These cuboid units are automatically assembled to obtain an approximate physical prototype. This paper details the algorithms used to generate the octree's assembly sequence and demonstrates the feasibility of the OcBlox approach by describing a single resolution example of a prototype built with this automated system. An analysis of the potential of the approach to decrease the manufacturing time of physical components is detailed. Finally, the potential of OcBlox to support complex overhanging geometry is discussed.