*5.1. Material and Method*

The picking experiment was conducted on 6 July 2022. The end-effector was mounted at the end of the arm based on the cartesian coordinate system. The maximum axial velocity at the manipulator's end is set to 0.8 m/s. Guided by ZED 2 (STEREOLABS, England) binocular stereo camera, the end-effector was sent to the position where it could pick the target fruit. Then, the end-effector worked and picked the fruit. In the harvesting experiment, the Arduino Due controller was used to realize the two-stage and two-index harvesting strategy.

A total of 72 cherry tomatoes were tested to verify the harvesting performance of the end-effector. There are two damage types to cherry tomatoes. (1) The skin of the cherry tomato is damaged, and the internal tissues are exposed. Then, the fruit develops mold or decay. (2) The cherry tomatoes skin is not damaged, but its cells are damaged. In this case, an enzymatic reaction occurs. The color of the pressed area darkens. When the tomato cells breathe faster, the tomatoes' water will be lost, leading to atrophy. Thus, picking success rate, the average picking time, the picking damage rate, the browning rate, and the wrinkling rate were used as measures of rapid and undamaged picking. The definitions are as follows:

$$T = \frac{\sum\_{1}^{h} T\_0 - T\_1}{h} \tag{21}$$

$$S = \frac{r}{h} \times 100\% \tag{22}$$

$$D = \frac{f}{h} \times 100\% \tag{23}$$

$$B\_t = \frac{p}{r-f} \times 100\% \tag{24}$$

$$C\_t = \frac{q}{r-f} \times 100\% \tag{25}$$

where *T* is the average time of picking, s; *T*<sup>0</sup> is the beginning time of picking, s; *T* is the time of unloading, s; *S* is the success rate,%; *r* is the number of fruits picked successfully; *h* is the total number of fruits; *D* is the damage rate, %, the damaged fruit was clipped by the end-effector; *f* is the damaged number; *Bd* is the browning rate, %; *p* is the browning number; *Cd* was the wrinkling rate, %; *q* was the wrinkling number; and *t* is the hours after picking, *t* = 24 h, 48 h, 72 h, respectively. The picked tomatoes were stored at an average temperature of 28 ◦C. Browning and wrinkling tomatoes were recorded. The picking experiment is shown in Figure 15.

**Figure 15.** Experiment of cherry tomatoes picking: (**a**) The system of picking robot; (**b**) Gripper picking.
