An efficient dynamic modeling methodology for general type of hybrid robotic systems

In this paper, we deal with the kinematic and dynamic modeling of hybrid robotic systems that are constructed by combination of parallel and serial modules or series of parallel modules. Up to now, open-tree structure has been generally employed for dynamic modeling of hybrid robotic systems. However, it requires not only expensive computation as the complexity of the system increases, but also must perform dynamic modeling for the whole manipulator again even if the partial portion of the robot structure is changed. Therefore, we propose an efficient dynamic modeling methodology for hybrid robotic systems. In the proposed method, initially the local dynamics of each of modules are obtained with respect to its independent joint coordinates and then the dynamics of the hybrid robot is calculated utilizing the concept of virtual joints that are attached to the base of each module of interest The virtual joints are assigned to have the appropriate number of DOFs in the operational space to represent the motion of all the proximal modules from the module of interest to the ground. For general multiple module-based hybrid robots, a recursive dynamic formulation of the proposed method is derived and the usefulness of the method is verified by comparing the computational efficiency of both the proposed method and the existing method.