Multiobjective Optimization of 6-DOF Parallel Manipulator for Desired Total Orientation Workspace

A desired total orientation workspace for a parallel manipulator is usually an essential requirement in a practical application. At present, for the multiobjective optimization method of 6-DOF parallel manipulator for desired total orientation workspace, it is needed to predefine maximal and minimal lengths of the legs to serve as the constraint, and then the numerical method is used to solve the length of the legs and judge whether the solved maximal and minimal leg lengths meet the constraint. Predefining maximal and minimal length of the legs limits of the optimal range, the numerical method has heavy calculation burden and low calculating accuracy. In this paper, a hybrid method for solving the maximal and minimal lengths of the legs of 6-DOF parallel manipulator with desired total orientation workspace is proposed, and the actuator stroke length is calculated according to the maximal and minimal leg lengths. By judging whether the actuator stroke length can be solved to serve as the constraint, without the predefined maximal and minimal leg lengths to serve as the constraint, the optimal range is enlarged. Aiming at the physical size of the parallel manipulator and the proposed desired workspace condition index (DWCI), the optimization of the geometric parameters of the parallel manipulator is conducted based on the multiobjective optimization algorithm (NSGA-II), which is subject to the actuator stroke length. Stewart platform is set as the example; the geometric parameters of the platform whose workspace contains the desired total orientation workspace are optimized and the hybrid method is proved to be more accurate and efficient compared to the traditional numerical method. This method provides the optimization guidance for engineering designers to design the parallel manipulator for desired total orientation workspace

Developing an information exchange scheme concerning value for money assessment in Public-Private Partnerships

Value for money (VFM) as the procurement justification assessment approach in Public-Private Partnerships (PPP) essentially justify the overall project feasibility in both qualitative and quantitative ways. However, the performance measurement in VFM still lacks automation and information exchange schema. Concerning the project management domain within the Architectural–Engineering–Construction/Facility Management (AEC/FM) sectors, Building Information Modelling (BIM) is emerging as a potential solution for owners to automate the process of value for money assessment. Based on the published performance structure in PPP procurement, This paper develops a novel schema to formalize the information exchange needed to support data extraction and performance measurement. The schema was achieved by referencing the standardised Information Delivery Manual (IDM), which specifies the required information exchanges. This proposed method facilitates the automatic VFM assessment thus benefit the PPP procurement. Software development and case study model are presented towards the validation of the schema and methods employed