## 5 Prototype and Experiments  
### Prototype Building and Performance Testing  
As shown in Figure 9, the prototype used in this experiment was composed mainly of a CDFM, an automatic spray-control system, and a tracked mobile platform. The main technical parameters of the prototype are shown in Table 3.  
Figure 9: The prototype of the CDTSR. The radius of the tubular unit was 40 mm and the distance from the adjacent end plate was 32 mm. Based on the established kinematics equation, the reachable space of the robot was obtained by using the Monte Carlo point method, as shown in Figure 10. From a fixed base, the reachable workspace was semispherical. The deformation of the cable will affect the accuracy of the manipulator, thus 304 stainless steel cable with better rigidity and flexibility was chosen. The spring was composed of carbon steel while the tubular unit was composed of resin and created via 3D printing. The control box required a sufficient strength and a light weight, so we choose aluminum to manufacture the control box. The repeated location accuracy measured by using the dial gauge was 0.532. To test the flexibility of the CDFM, a branch obstacle avoidance experiment was designed. The CDFM needed to circumvent the branches and enter into the tree canopy to achieve target spraying. The reachable space and position of the manipulator to the model tree are shown in Figure 11a; the size of the model tree is shown in Figure 11b. The 3D model of the model tree was established by using a Ready Scan B11 3D scanner and placing the model tree and the manipulator under the same coordinate system. According to the coordinate position of the obstacles, the motor rotation angle was obtained by using the established kinematics model. Through programming of the upper machine, the motion trajectory of the manipulator was determined. Then the manipulator could avoid obstacles according to predetermined trajectory. The sensor and camera could also be installed to realize automatic \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Components** & **Parameters** & **Values** & **Name** & **Model** & **Company (Country)** \\ \hline \multirow{9}{*}{Cable-driven flexible manipulator} & Distance & & & & Wenzhou Pufeide \\  & between adjacent & 40 mm & Stepper motors & 86 BYG250D-14 & Electric Co., LTD. \\  & end plate & & & & (Wenzhou, China) \\  & Radius of & & & & Wenzhou Pufeide \\  & tubular unit & 32 mm & Microstep & MA860H & Electric Co., LTD. \\  & tubular unit & & & & (Wenzhou, China) \\  & & & & & Dongguan QiSuo \\  & Length of & & & battery & & (Dongguan, China) \\  & Number of & & & & STMicroelectronic \\  & tubular units & & & & (Geneva, Switzerland) \\  & Dimension of & & & & & Jiangsu Langshan \\  & control box & \(350\times 350\times 350\) mm & Cable & \(1\times 7\) & Write Pope Co., LTD. \\  & envelope & & & & (Nantong, China) \\ \hline \multirow{9}{*}{Automatic spray-control system} & Maximum & & & Lithium & DC-12V & Dongguan QiSuo \\  & pesticide load & & battery & & & Electronics Co., LTD. \\  & & & & & (Dongguan, China) \\  & & & & & & (Dongguan, China) \\  & & & & & Taizhou Sprayer Plant \\  & Diaphrag & 60 W & Diaphrag & FD-G4000Z & Protection Machinery \\  & pump power & & & pimp & Co., LTD. (Taizhou, China) \\ \hline \multirow{9}{*}{Tracked mobile platform} & Boundary & & & & Beijing Times \\  & dimension & & & & Chaoqun Electric \\  & & & & motor & Technology Co., LTD. \\  & & & & & (Beijing, China) \\  & & & & & (Beijing, China) \\  & & & & & (Beijing, China) \\  & & & & & (Beijing, China) \\  & & & & & (Dongguan, China) \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Main technical parameters of the CDTSR. obstacle avoidance. However, a method to achieve a more effective automatic obstacle avoidance remains to be explored.