2.4.1. Vertical Transportation of Grape Cluster

Three different grape clusters were used as an experimental material because the study's aim was to analyze the vibration mechanism of the hanging grape cluster in different zones of vertical transportation, which was difficult to do using real grape clusters. For understanding the berry drop mechanism of grape clusters due to vibration, an actuator is moved linearly on the rails of the lead screw lathe according to the input speed and acceleration excitations from the PLC (programmable logic control), as shown in Table 1. A vertical start and stop transportation test setup of grape clusters was constructed, as shown below in Figure 4a. Due to the actuator movement, the excitations are transferred from the gripper towards the berries through the main rachis, and the hanging grape cluster starts to vibrate. The magnitude of the cluster's vibration during vertical transportation is determined from the force sensor signals. The excitation displacement or stroke length was adjusted to 0.8 m from the start to the stop point [62]. Additionally, the vibration characteristics of the grape clusters during the different phases of vertical transportation were analyzed.


**Table 1.** Different excitation treatments applied to the actuator for the transportation of grape clusters.

**Note:** A duty cycle is the time taken by the actuator to complete one stroke (stroke/time) from the start to stop positions.

**Figure 4.** Vertical start and stop transportation placing cycle: (**a**) vertical transportation; (**b**) placing view.
