###### Abstract
A two-footed climbing robot that uses vacuum suckers was used to adhere to the rotor blade or to the tower [20], the Lego-based robot for the inspection of wind turbine parts with diagonal ropes and rubber bands was employed for the connection to the tower [21], and the climbing ring robot for offshore wind turbines can climb around cylindrical towers [23]. After reviewing the wind-turbine-climbing robot with its two important mechanisms, the functionality of its locomotion and adhesion, this study proposed four rubber wheels that perform locomotion and a winding mechanism that provides enough adhesion to the wind turbine tower. \begin{table}
\begin{tabular}{c c c} \hline \hline
**WT Physical Defects** & **Description** & **References** \\ \hline Corrosion & A different characteristics attack by a high or unwanted levels of humidity inside and outside the wind turbine system. & [7] \\ Cracks & It is due to extreme loads on the tower, improper manufacturing, poor material and structural design and excessive environmental factors. & [8; 9] \\ Paint peel-off & The paint peel-off caused by the elements of wind, raindrops, airborne sand, temperature changes, and acidy from bug carcass. & [11] \\ Material Degradation & Internal interfaces in the composite material components that are potential weak links; with their greater exposure to higher levels of moisture and salt. & [13] \\ Lightning Strike & It is due to tall structures that are attractive to lightning, especially when located in flat planes. & [14] \\ Other surface defects & This is caused by erosion (rain erosion, sand, and hail), or small object impacts. & [12] \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Types of physical defects occurring in the structure of wind turbine. The paper aims to develop a wind-turbine-tower-climbing robot with a high payload capacity to install additional equipment and to withstand the impact of wind disturbances. The locomotion mechanism is a wheel-based method for a quicker and more robust climb. The four rubber wheels create enough friction as it rolls over the tower's surface, preventing it from slipping. By combining rubber wheels as its locomotion mechanism and a winding mechanism through a Bowden cable force, one can maintain its position on the tower surface without it slipping to the tower base and increase the contact on the tower surface to achieve a high payload capacity. Concerning the robot carrying load capability, an additional component in the body frame through the aid of the caster wheel was added to optimize its stability for carrying ancillary equipment to perform specific application tasks of wind turbine parts and wind disturbances. With these goals, the carrying load was roughly more than 50% of the robot's weight that was protected from breaking or slipping. This climbing robot can perform a straight up-down movement on the tower surface. The other unique characteristic of the proposed design was that it can achieve wind gust disturbance's ability and innovative structure to estimate the robot position in the manner to maximize its capacity for climbing, which were the main drawbacks of the existing climbing robots. This paper was organized as follows: Section 2 presents a description of the wind-turbine-tower-climbing robot, kinematic and dynamic equation of motion, control system and experimental set-up. Section 3 was devoted to the experimental results performed of the various speeds and subject to payload capacity and the indoor testing conditions, and Section 4 provided the conclusions and future works.