## 1 Introduction
Two-way communication between the two models was established using named pipe technology. The proposed approach is applied using the example of the mobile robot FESTO Robotino [59]. The basic premise is to provide a connection between the developed virtual model and its dynamic model, created using another software package [60]. FESTO Robotino is complex enough to be chosen as a representative example. It is characterized by excellent maneuverability, which is achieved using three omnidirectional wheels. As such, it is the subject of many analyses [61; 62; 63; 64; 65; 66; 67; 68]. Generally, the design and development of omnidirectional wheels have also received a good deal of scholarly attention [69; 70; 71; 72]. The dynamic models for various mobile robots were developed several decades ago, but, due to the complexity of omnidirectional wheels [63; 64; 65; 66; 67], the attention of researchers around the world is still focused on dynamic modeling and the design of an appropriate control algorithm for the navigation of mobile robots that are equipped with such wheels [73; 74; 75]. In our study, we analyzed the lateral rolling of the rollers that comprise the wheels. A dynamic model, based on the concept of the component model approach, was created using the bond graph technique in BondSim [60; 76]. The virtual 3D model of Robotino presented here was developed using an XML approach in the BondSim3 DVisual application. The methodology for the development of the virtual model presented here is an updated, modified version of the method presented in [77]. The proposed markup language is a simplification of the general XML scheme found elsewhere [58], and it serves as a replacement of a C-type language introduced in BondSim3 DVisual [60]. The proposed version was designed for the 3D geometric modeling of articulated bodies, such as robots, multi-finger robot hands, mobile robots, multi-leg platforms, cranes, and similar objects. Using a DOM (document object model)-like approach, an XML document can be represented as a tree of elements. Thus, the structure of the 3D geometric model of an articulated mechanism can be represented as a tree of constitutive elements and attributes in the computer memory. The virtual 3D model is generated from an XML tree using the powerful VTK library [78; 79; 80]. Between these two processes--the virtual, which works in the BondSim3 DVisual environment, and the dynamic simulation, which runs in the background of BondSim--there exists a two-way communication based on named pipe techniques. After validation in a virtual environment, the proposed algorithms can be applied to a real robot. Verification of the robot's behavior in a virtual scene reduces the need for extensive experimental work with real robots. FESTO implements a similar idea for Robotino using two software packages: RobotinoView for driving Robotino and RobotinoSim to visualize a workplace using Robotino [81; 82]. The approach presented here is more general and refers to the development of dynamic and virtual 3D models for any articulated mechanism, not only Robotino. Such models can exchange information with each other in planned future research on real physical systems according to the concept of digital twins. The rest of this article is organized as follows. The methodology for developing a virtual 3D model of an articulated mechanism is described in Section 2. The dynamic model of Robotino, developed using bond graphs, is presented in Section 3. The simulation results are presented in Section 4. Finally, we offer some concluding considerations and propose directions for future work.