Digital twins provide a powerful tool for testing and maintaining products and processes in several application fields, including manufacturing, smart cities, healthcare, and agriculture, aiming to optimize operational efficiency, resource usage, and planning accuracy. Research presented in this paper deals with the development of the digital version of off-road vehicles. Two different robot simulation frameworks are investigated. The first one is based on Gazebo, an open-source 3D robotics simulator, to test and validate the algorithms developed in the ROS framework; the second one adopts the vehicle mechanical assembly in MSC Adams, a multibody modeling software used to study the dynamics of complex mechanical systems. Both models are developed for a tracked robot that uses an innovative articulated passive suspension system on either side that allows each ground wheel to move independently with respect to the vehicle body, providing remarkable adaptability to irregular terrain. In addition, a Gazebo model is developed for a four-wheel drive/steering robot, including robot sensors such as GNSS, IMU, and visual sensors and a model of a typical agricultural environment (i.e., a vineyard). The paper presents the details of model design and implementation while investigating the best choice in developing the digital twin of off-road vehicles operating in the field. Additionally, an agricultural scenario has been selected as a use case to facilitate the evaluation of the analyzed frameworks. Our findings demonstrate that the Gazebo framework could serve as a suitable robot simulation framework for creating digital twins of vehicles, provided it incorporates real-time sensor measurements designed for identifying soil-wheel interaction dynamics. In contrast, the multibody model provides a higher-fidelity dynamic model, including track-terrain interaction. Despite its advantages, this model has substantially higher computational costs, which limits its applicability to real-time simulations, making it less feasible for practical use in the field.

The Power-Split Continuously Variable Transmission is one of the most promising architectures for Hybrid Electric Vehicles. These systems have been introduced to improve vehicle global efficiency since they can maximize the efficiency in varying operating conditions. During the design stage, the availability of modeling tools would play a key role in achieving optimal design and control of these architectures. In this work, a compound power split device that combines an electric Continuously Variable Transmission with two planetary gear trains is analyzed. A comprehensive model is derived that allows the different power flow configurations to be evaluated given the properties of the single subcomponents of the system. The efficiency of the powertrain can be derived as well, and a numerical example is provided. The architecture studied has an efficiency that can be higher than that obtained using one single eCVT for most of the global transmission ratio range, showing that this solution could be suitable as a part of a more complex compound transmission that engages in a specific speed range.