Assembly planning and evaluation in an augmented reality environment

Abstract

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. IntroductionAs the competition of the manufacturing industry is increasing throughout the world, many companies tend to improve product quality, reduce product development cost and shorten time of design-to-assembly for new products. Assembly processes constitute a majority of the cost of a product (Boothroyd and Dewhurst 1989). In the assembly planning process, assembly sequences which are the backbone of assembly plans are generated and assembly operations which describe how different parts will be assembled together are formalised. Production efficiency will be improved and a large amount of cost will be reduced if a product is assembled according to a well-planned assembly sequence.Traditionally, assembly sequence planning has been conducted by either product designers or production engineers manually using either 2D drawings or physical prototypes of the product based on their intuition and experience. Nowadays, since products have become increasingly complex and the number of components has increased exponentially, manual assembly sequence planning has become impractical. In addition, physical prototyping is time-consuming and expensive for users to verify the ease of assembly. Moreover, additional cost will be incurred if there is any design change of certain components of the product. The rapid development of computer science and technology provides an alternative to solve this issue. In order to ease assembly sequence planning, research efforts have been made ...

Augmented reality technology in the manufacturing industry: A review of the last decade

“…This is consonant with the fact that HMD instructions are more effective than paper instructions (Tang et al, 2003) and that the use of mobile devices decreases the risk of errors in assembly operations. Bare-hand solutions instead have been primarily adopted in the (augmented) Tablets, smartphone or other mobile devices 1 2 3 2 3 2 3 8 7 6 1 0 4 51 assembly process, probably because assembly is a manual process where ergonomic issues cannot be ignored (Azuma, 1997;Wang, Ng, Ong and Nee, 2013). Tracking systems for AR can be classified into two main categories, namely "marker-based tracking" and "marker-less tracking (Ababsa et al, 2010).…”

“…From this list it can be seen that some keywords (e.g., "tracking" or "interaction") falling under the category of well-established research topics actually describe very general concepts or common technical problem when developing AR solutions; therefore, they are likely to be mentioned with a higher frequency by researchers. The use of AR for assembly is primarily motivated by the fact that, on the one hand, assembly processes constitute a significant portion of the cost of a product Wang, Ng, Ong and Nee, 2013) and that, on the other one, this cost can be dramatically reduced if a product is assembled according to a well-planned assembly sequence. AR is therefore used to this end, in the attempt to automate the process and enhance its efficiency.…”

A systematic review of Augmented Reality content-related techniques for knowledge transfer in maintenance applications

“…Within 'design' operations, one of the most relevant fields is the design, planning and simulation of assembly procedures. Different papers have shown different Authoring tools for automatically creating assembly procedures based on real and virtual components [60,61]. Based on visualising assembly procedures, user-virtual components-interaction capabilities have been included in following works, in order to enhance design and planning effectiveness.…”

“…That is the case of Wang, Ong and Nee [62]; they proposed a bare-hand interface to contextualise the manipulation of virtual components. Moreover, they extended their own work with Interaction-Analysis methods to evaluate the status of assembly situations based on user interaction and provide more accurate assembly simulations [63,64]. Additionally, other design applications have been proposed in the context of 'small' assets.…”

On Pose Estimation in Room-Scaled Environments

“…• support in everyday professions such as archaeology [29,105], engineering, architecture and construction [66,79,98,132], and medicin and rehabilitation [61,65,92];…”