Researchers and practitioners have attempted to solve problem of robot control by using of well-proved product models. Existing product modeling methods offer quasi integration because appropriate integrated robot process model is not available. The authors propose a modeling of the robot system that has the capability of integrated description of product, robot and robot process. Advanced concepts as feature and associativity definitions together with task oriented robot process gained an extended application in the proposed model. This paper presents the new modeling for integrated application of part, assembly and robot process models at robot assembly of mechanical products. The main purpose of this integration is product model driven definition of robot assembly trajectories. The main contribution is an attempt to define shapes and part positions for robot assembly by using of form features instead of geometric elements. Form feature model objects carry intent of engineers for technical content of modeled environment. The paper introduces actual issues of robot assembly and outlines the concept of the authors for product model driven modeling of robot assembly. Information for assembly in feature based product model and robot process model features are explained. Following this, an extended feature concept for modeling of robot system is discussed. Finally, integrated model of robot assembly system and role of form features in it are concluded.