**4. Conclusions**

In this paper, our aim was to observe the effect of different speed and acceleration excitations on the berry drop mechanism during the vertical transportation and placing of grape clusters. Force sensor signals and high-speed photography images were used for the verification of the deflection mechanism of the berries under different packaging materials. The following conclusions were drawn from this study:


Thus, research in this paper can act as a guide for the harvest and post-harvest robotic handling of cluster fruits such as grapes, cherries, blueberries, and litchi. The proposed study can be used to realize optimal control of the transportation and placing of the robot. Overall, this study provides technical and theoretical support for the industrial needs of low-loss robotic handling of different fresh-eating cluster fruits that are consumed abundantly. In the future, dynamic impact or collision between grape cluster berries during robotic post-harvest handling will be discussed.

**Author Contributions:** Conceptualization, J.L. and M.F.; methodology, M.F. and J.L.; software, M.F. and G.C.; validation, M.F., J.L., and G.C.; formal analysis, M.F. and J.L.; investigation, M.F., J.L., and I.A.; resources, M.F., J.L., and I.A.; data curation, J.L., M.F., and B.X.; writing—original draft preparation, M.F.; writing—review and editing, M.F., J.L., Z.S., and K.Y.; visualization, Z.S., and I.A.; supervision, J.L.; project administration, J.L.; funding acquisition, J.L. All authors have read and agreed to the published version of the manuscript.

**Funding:** The research was supported by grants from the National Science Foundation of China (Grant No. 31971795) and a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions (No. PAPD-2018-87).

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

**Acknowledgments:** The authors are grateful to the National Science Foundation of China. The first author gives many thanks to the China Scholarship Council (2017GXZ026592) for providing 36 months of scholarship for studying in the People's Republic of China.

**Conflicts of Interest:** The authors declare no conflict of interest.
