**9. Conclusions**

The proposed controller exhibited an acceptable performance even in the presence of parametric uncertainties and noisy measurements. The hybrid structure allows for dealing with the WRBD represented by two link robot manipulators alternating between their first and last links as a reference for its working space. This result constitutes one of the first ADRC approaches dealing at the same time with hybrid systems with restricted variables. A barrier technique imposed angular restrictions in the robotic device avoiding any damage to its physical structure. Moreover, the H-ADRC controller reduces the steady state error compared with classical output feedback structures like state-feedback (PD form) and extended state state feedback (PID structure).

**Author Contributions:** Conceptualization: I.S., D.C.-O. and I.C.; Methodology: V.L.-O. and A.G.; Software: A.G. and M.M.-S.; Validation: V.L.-O., A.G. and M.M.-S.; Formal analysis, I.S. and D.C.-O.; Investigation: V.L.-O. and D.C.-O.; Resources: I.S. and I.C.; Data curation: V.L.-O. and M.M.-S.; Writing—original draft preparation: V.L.-O. and I.S.; writing—review and editing: I.S. and I.C.; supervision: I.C.; project administration: I.S., D.C.-O. and I.C.; Funding acquisition: I.S., D.C.-O. and I.C. All authors have read and agreed to the published version of the manuscript.

**Acknowledgments:** The authors acknowledge the support and funding offered by the National Polytechnique Institute via the Grants labeled SIP-2019-5253, SIP-2019-5253 and SIP-2019-6849 .

**Conflicts of Interest:** Authors declare not any personal interest that may be perceived as inappropriately influencing the representation or interpretation of reported research results.
