Morlock, MerlinMerlinMorlockMeyer, Niklas JoachimNiklas JoachimMeyerPick, Marc-AndréMarc-AndréPickSeifried, RobertRobertSeifried2021-01-082021-01-082021-04Mechanism and Machine Theory (158): 104220 (2021-04)http://hdl.handle.net/11420/8349Real-time end-effector trajectory tracking is applied to a newly developed parallel robotic system with two highly flexible links. In contrast to previous works, which are typically based on offline precalculations or rigid model inversion, a dynamic flexible multibody model is inverted online. As the underactuated system is non-minimum phase, the inverse model needs to be rendered stable for real-time integration. Therefore, three approaches are developed for the considered robot. Firstly, output redefinition is applied by directly weighting the elastic deformations and rotations of the links. Secondly, a small counter weight is attached at an advantageous location on the robot having only a minor influence on the eigenfrequencies. Lastly, the rotational degree of freedom of the end-effector is used to stabilize the internal dynamics of the inverse model with a small motion of a rotary motor. The concepts and real-time applicability are validated within experiments which extends the related literature being highly based on theoretical investigations. The experimental end-effector tracking performance based on the three minimum phase approaches is close to the desired trajectory and clearly outperforms classical rigid body inversion.en0094-114X2021Flexible linksInternal dynamicsModel inversionParallel robotReal-time controlUnderactuated robotJournal Article10.1016/j.mechmachtheory.2020.104220Other