## 1 Introduction  
The scope of the current paper is to apply advanced CAD (computer-aided design) knowledge within dedicated modules, using specific tools for simulation and calculus oriented on workspace capabilities and other aspects related to the robots having PKM (parallel kinematics machines) structures. Modern manufacturing systems, in means of structures, are designed with the aim of changing their usage domain using interchangeable end effectors. Ref. [1] underlines that before implantation, all aspects regarding processes or product validation undergo tests through simulations using digital manufacturing. In many industrial applications where robotic structures are involved, characteristics regarding the ability to change position and orientation with a high precision ability are a fundamental requisite. It is known that all these robotic tasks are performed with a limitation in terms of the range of rotation or even the workspace volume [2]. Adequate element meets the requirements by simply making precise movements within their range of six degrees of freedom. For the first time, as it is presented in the literature, these parallel kinematics machines were used in the aircraft industry in the tires test [3; 4; 5; 6]. In terms of the practical applications within different industries where implemented parallel robotic architectures can be found, the following tools can be underlined: parallel machine tools [7], vibration simulators with six DOF (degrees of freedom) [8] and/or motion simulators [9].  
One of the key challenges within these novel PKM structures are related to their capabilities regarding the workspace. Workspace analysis of a parallel kinematic machine (PKM) using tools from a CAD optimization software offers the possibility to identify the movements, volume, and trajectories. It also indicates if there are any problems due to kinematics that need to be calculated or identified, regarding the parallel robots' structures that focus on inverse or forward kinematics [6]. In the article, the relations between the robot workspace and the design parameters are demonstrated, a method that can be applied for other parallel structures as well. The method is useful for robot designers in the optimization of parallel robots with regard to the workspace by using CAD tools. Previous research in the field refers of the usage of CAD tools only for visual representation and not for optimizing the workspace [10], while this study and test results show that CAD tools are suitable for analyzing and optimizing the robot workspace of the 6 DOF parallel robots, due to its easiness in application and fast implementation time.  
The present work is focused on the functional design of a parallel kinematic machine (PKM) with six degrees of freedom (DOF). We studied and presented the aspects regarding the workspace determination via CAD techniques as well as numerical techniques.  
The present study deals with the aspects mentioned above and starts with the theoretical side that is realized in the digital CAD space, before moving to the validation area by comparison with the analytical calculation level. The motivation for this research was to develop a novel PKM structure that has six DOF capable of adapting to different types of assembly process in a manufacturing plant.