# The Kinematic Analysis of a Wind Turbine Climbing Robot Mechanism
## 1 Introduction  
The emergence of renewable energy is evident through the utilization of wind energy towards achieving a clean energy transformation. The world will become renewable-driven as new clean technology continues to be a core element of a strategy to revitalize the global economy. The demand change continues with an unprecedented shift that confronts some critical tasks to achieve wind turbine lifetime objectives while reducing the cost of inspections and maintenance because of various conditions such events of grease, hydraulic oil, flying planktons, extreme temperatures, wind speed variances, moistness, dust, radiation, lightning, saltiness and successive storms of rain, hail, snow, and sand [1]. Such events can create physical defects of the wind turbine that is difficult to detect in the early stage and can have a substantial effect on its performance efficiency over time. Detecting the wind turbine physical defects, corrosion, cracks, rust, loose bolts, material degradation, and faults are of great importance to improve the service life of wind turbines for long term operation [2,3]. Figure 1 shows the influence of various wind turbines' physical problems susceptible to environmental conditions and other factors. The enormous wind energy growth offers opportunities for academe and industry to do scientific discipline, research innovation, and technological developments on wind turbine application robots to perform specific tasks. Such specific purpose and diverse application tasks are cleaning, painting, welding, repairing, material handling, object manipulation, inspection, diagnosis, and maintenance. The emergence of robots in wind turbine plays an important role in diverse applications that meets the need for demand and reduce maintenance cost. A climbing robot is a robotic system that is equipped with an appropriate locomotion and adhesion mechanism for adapting to the given environmental requirements [4]. A great number of studies have been devoted to wind turbine application with its various types of experimental prototypes and products have been proposed. For example, as shown in Table 1 the first model is the development of a \"ring\" climbing robot with a payload capability allowing it to climb around the cylindrical tower. The prototype has three modules that are completely identical and can be easily joined together to climb on any circumferential tube. The wheels depend on spring forces to grip around and climb on the tower. The innovation of the robot is that its adhesive forces are provided entirely by springs rather than conventional adhesion methods (such as vacuum suction, magnetic force, and dry adhesions) [5]; its drawback is that this type of locomotion needs an additional mechanism to turn the wheels at a certain angle to do the different movement states. The second model consists of a magnetic climbing robot for the inspection and maintenance of a wind power tower that utilizes four common kinds of strong magnetic units as one of the key components that adheres the robot to the tower. The robot is a track-based locomotion that has two modules connected with joints, and each module contains two tracks where steel segmented magnets are integrated. There are six magnetic units in one row-track that keep in contact with the tower surface as a plane [6]; its drawback is that this type of locomotion cannot directly change its own movement states. The third model is the two feet climbing robot on the rotor blade of the wind turbine. Its climbing technique is a modular approach that has two feet and three degrees of freedom, and each foot has three vacuum suckers installed in the vertex of the triangle to keep the robot in contact with the rotor blade. The robot can climb with a swing-around gait since the mechanical structure consists of a foot module and body module [7]; its drawback is that this type of locomotion does not an easily execute various types of movement states due to its periodic gait patterns and adaptive gaits.