Fazhi He

A method and tool for human-human interaction and instant collaboration in CSCW-based CAD

From human-computer interaction to human-human interaction and from information sharing to instant collaboration are major advances from traditional standalone and distributed CAD to collaborative CAD. This paper explores model, method and tool to achieve this goal. A human-centered collaborative design model to support human-human interaction is presented. A method to transparently add aware capabilities to single-user CAD applications is outlined. Based on the method, an instant collaboration tool is implemented to support human-human interaction in collaborative design process. The collaboration tool involved some core collaborative issues such as agent structure, communication, group awareness, consistency maintenance and collaborative tasks. We also test the method in a 3D collaborative tool for heterogeneous CAD applications.

A method for topological entity correspondence in a replicated collaborative CAD system

In order to utilize the potential advantages of replicated collaborative CAD system to support natural, free, fast and less-constrained multi-user human-to-human interaction, a local-locking mechanism, which can provide fast modeling response, is adopted as concurrency control mechanism for a replicated on-line collaborative CAD system. A human-human interactive modeling is achieved by immediate local execution of modeling operations and exchange of modeling operations across all collaborative sites real-time. In particular, an approach to achieve topological entity correspondence across collaborative sites during modeling procedure, which is critical to guarantee the correctness and consistency of collaborative modeling result, is proposed. A prototype system based on the ACIS geometric modeling kernel is implemented to verify availability of the proposed solution.

A hybrid optimization approach for sustainable process planning and scheduling

Process planning and scheduling are important stages in manufacturing, and good strategies can significantly improve the energy performance of manufacturing to achieve sustainability. In this paper, an innovative optimization approach has been developed to facilitate sustainable process planning and scheduling. In the approach, honeybee mating and annealing processes are simulated to optimize multi-objectives including energy consumption, makespan, and the balanced machine utilization. Experiments on practical cases show that the optimization results from this approach are promising in comparison with those from a genetic algorithm, a honeybee mating optimization algorithm, ant colony optimization, and a simulated annealing algorithm, respectively.

Encryption based partial sharing of CAD models

Model security for collaborative product development ina networked environment (or called networked manufacturing, grid manufacturing, and cloud manufacturing) is an important and also challenging research issue. An encryption based partial sharing approach for CAD models has been developed and presented in this paper. First, a random invertible decimal matrix to support the encryption approach is proposed, with which parts of a CAD model can be selected flexibly by the model owner for encrypting by different keys; Second, in order to guarantee the security, a dual-key mode and a key based authorization mechanism are proposed. Based on the model, different levels of security are achieved based on different key spaces, and the key based authorization mechanism is used for the model owner to control the partial access of the CAD model flexibly.

Using procedure recovery approach to exchange feature-based data among heterogeneous CAD systems

Data exchange is one of key issues in collaborative design. The purpose of feature-based data exchange is that the target model is editable after being exchanged. This is the reason why nowadays feature-based data exchanges become the research focus beyond the traditional geometry-based data exchange. This paper presents a two-stage mechanism to recover a complete modeling process of a parametric CAD mode in source systems. Therefore, what we exchange is the procedure of modeling steps. In target systems, we use the exchanged procedure to simulate a real human to reconstruct the parametric CAD mode in any heterogeneous CAD systems. The proposed method has been tested with case studies among typical CAD systems, such as SolidWorks, UG, Pro/E and Catia.

A Direct Feature Retrieval and Reuse Method for Heterogeneous Collaborative CAD Systems

Nowadays a lot of enterprises develop the products collaboratively using heterogeneous CAD systems. Feature based data exchange and interoperation among heterogeneous CAD systems are very important in pervasive computing environments. The key techniques in feature based data exchange are feature retrieval (extraction) and feature reuse (reconstruction). This paper presents a direct approach for feature retrieval and feature reconstruction. At first, most of feature information is directly retrieved by first retrieval mechanism in source systems. Then, the secondary retrieval mechanism acquires related information which can not be retrieved in first retrieval. At last the feature model is reconstructed one by one accurately in target systems by the model reconstruction mechanism.

A road map on human-human interaction and fine-function collaboration in collaborative integrated design environments

From human-computer interaction to human-human interaction and from information sharing to function collaborative are major advances from traditional single-user design to collaborative design. This work presents a road map to achieve this goal with computer-aided tools. The models, methods and techniques in developing collaborative tools for collaborative integrated design environment are discussed in details. The proposed ideas have been implemented in an aware collaborative tool to support transparent CAx/DFx systems.

An multiuser Undo/Redo method for replicated collaborative modeling systems

Undo/Redo can help rolling the whole system back to some previous state. However, many group Undo/Redo researches are based on co-edit system of text object. This paper firstly addresses the Undo/Redo in 3D collaborative solid modeling system. After analysis of the existing Undo/Redo method, this article proposed a multiuser Undo/Redo method in replicated collaborative modeling system. The implementation of the Undo/Redo operation in both local site and remote site is described in detail respectively. In our method, the users intention can be preserved. The preservation is based on dependency relationship among users at different sites. The proposed approach has been tested in a prototype system with case study.

A Transformation-Based Method for Name Converge in Quiescent Context of Replicated Solid Modeling Systems

Name converge is the footstone of converge problem in replicated collaborative solid modeling (CSM). In order to explore name converge in quiescent context, both collaboration status and solid status in replicated CSM are analyzed. Based on the analysis, a details roadmap for name consistency is presented. As part of details roadmap, a name converge method is proposed. The method transforms definition (local) name of a topological entity into execution (remote) name of the entity. The transformation rules utilize both context conditions for transformation and topological position in split faces

Using a middleware agent to bridge standalone CAD systems for distributed and collaborative applications

A method to bridge standalone CAD systems is presented. The method uses a middleware agent to wrap the standalone CAD systems. Both inside and outside encapsulations are constructed inside the agent. The online bridge has been initially implemented to integrate commercial CAD systems for distributed and collaborative applications.