Design gene based secure mechanism for collaborative product development

Abstract

In collaborative product development, a CAD model needs to be effectively shared among partners to facilitate co-design. In the meantime, it is essential to preserve the intellectual property information (design knowledge) of the shared CAD. To resolve the above dilemma, this paper presents a novel approach to share CAD models to support collaboration, as well as conserving confidential design knowledge in the models. The motivation of the approach is to develop collaborative mechanisms pertaining to an innovative concept of design genes, which imitate biological genes that are responsible for the heritable characteristics of an organism during evolving. The approach consists of the following steps. Firstly, design genes are defined to represent the design knowledge in CAD models. Secondly, a filter is introduced to retrieve design genes from the CAD model flexibly. An encryption algorithm is then designed to encrypt the design genes, and ensure the geometrical validity of the model to support effective collaboration. Finally, case studies are used to validate the developed approach. The complexity of the case studies can demonstrate that the approach is applicable to real-world application scenarios.

Introduction

The 80% product design is based on the former designed CAD models, and the value of the reused CAD models is their inner solidified design knowledge which is the confidential information and the essence of design ability. Facilitated by the state-of-the-art ICT technologies, collaborative product development via the internet has become widely carried out in design companies. A group of designers who are geometrically dispersed are able to work on the same CAD models jointly [1]. On the other hand, as co-designers could be from different organisations, when a model is shared for collaboration, the confidential design knowledge might be inappropriately obtained or misused [2], [3], [4], so that it is challenging to effectively preserve the intellectual property information (confidential design knowledge) of co-designed models [5], [6].

In the collaborative environment, the confidential design knowledge might face two risks: (1) It would be intercepted in the storage and transmission process; (2) It would be leaked when the CAD model is shared and interoperated by the collaborators. For the research of CAD model security, developed approaches include watermarking, access control, data encryption and so on [7], [8]. These approaches are mechanisms for CAD model protection as a whole, while ineffective to protect non-disclosed IP information (design knowledge) when the model is shared. As Fig. 1, in the collaborating process, all the design information CAD model 1 is protected in the storage and transmission, but the confidential design knowledge is open to the collaborator2 in sharing and would be reused by the collaborator2.

In order to protect the design knowledge during the sharing and interoperation of CAD models, three key problems should to be solved:

• What is the design knowledge to be protected. The design knowledge is a kind of solidified design experience accumulated year by year, which has high reuse value. And the design knowledge should has a stable structure with complete design semantics and clear design intent (including both the internal structure of features and the topological structure among features), and the stable structure will influence and guide the future evolution direction of design, which is not possessed by a single design feature.

• How to identify the design knowledge in shared CAD model, which is hidden in CAD model and hard to be identified. The identification of design knowledge is different from the feature recognition: First the identification of design knowledge is aim to find a group features with a stable structure from a feature based CAD model for reuse and protection, but the feature recognition is aim to recreate a feature in a geometric CAD model for parametric edit; Second, the design knowledge comes from the initial designer, but the recognized features would not be consistent with the design history.

• How to protect the design knowledge during the sharing and interoperation of CAD models, as the CAD models are complicated and most of the CAD systems are constrained systems, and any change would lead to failure CAD models easily. As thus, the traditional encrypting method just treat the CAD model as a whole file, which cannot support the free sharing and interoperation when the CAD model is encrypted. In order to support the free sharing and interoperation, the encryption method for local design knowledge is necessary.

To address the challenge of secure sharing of CAD models in collaborative design, this paper mimics the concept of biological gene to define the design knowledge in CAD models as Design Gene (DG). Refer to the isolation mechanism, an innovative approach for DG based secure sharing of CAD models is presented (as Fig. 2). Before a CAD model is shared to collaborators, DGs in the model corresponding to the related design knowledge are identified and encrypted. Meanwhile, the CAD model still parametrically represented to be shared flexibly. The innovations and distinguishing characteristics of the approach include:

• An innovative concept of Design Gene (DG) for a CAD model is defined. DG, which represents the design knowledge in the model, is defined as a protected unit in the model. Meanwhile, the representation schema of DG is defined. A data structure representing DGs and a Filter extracting DGs from the CAD model are developed. An extracted DG includes the topology of a group features, the feature types and the inner sketch topologies of the features.

• An encryption algorithm for DGs is introduced. The DGs in a collaborative CAD model will be encrypted parametrically and geometrically. The confidential information of the DGs are protected and the collaborative CAD model is still kept parametrical to be shared and interoperated flexible.