# Design and Experiment of a Novel Facade Cleaning Robot with a Biped Mechanism
## 1 Introduction
developed a climbing cleaning robot hanging down from a crane. They prototyped the robot and demonstrated its effectiveness via experiments in real conditions [29]. The methods of the literature are effective and valid, as shown by the experimental results. Even though numerous studies in the literature have demonstrated the use of glass facade cleaning robots, conventional platforms experience a system failure with respect to area coverage, which degrades their full efficiency. One major factor in glass facade structures that affects the performances of facade cleaning systems is the frames that connect the two glass panels. These frames generally act as a barrier for glass facade cleaning robots to cross over from one glass panel to another, which leads to a performance degradation in terms of area coverage. One viable approach to overcome these difficulties in facade structures is to develop a facade cleaning system with a biped mechanism that can overcome these obstacles. In the field of robotics, there have been several biped robots that have been reported in the literature for different application scenarios. [PERSON] et al. [30] proposed a novel biped walking machine for domestic service purpose. The proposed robot was designed as an experimental system for studying biped locomotion based on torque-controlled joints, and the experimental results were discussed by utilizing the scheme. In another work, [PERSON] developed a low-cost educational system to study and control a biped robot in real time [31]. The proposed system used MATLAB for visualization control. Arduino was used as a low-level controller to manage the walking gaits of the biped robot. [PERSON] and [PERSON] developed a novel biped robot to obtain patient data from a Japanese patient office [32]. This particular study applied a three S-Curve model to analyze the acquired data. In addition, the analyzed information was used to foresee the development trend in the field of biped robot walking. Biped robots have been proposed for wall climbing and inspection purposes. The authors in Reference [33] proposed Climbot, which was developed based on the climbing patterns of leech worms. The presented robot was developed under a biped concept with five degrees of freedom and two special grippers as end effectors. Similarly, an urban reconnaissance climbing biped robot is presented in Reference [34]. The developed robot was under-actuated and made smaller in order to access confined spaces. The study discusses the evaluation process of the robot's performance while navigating on inclined surfaces. In spite of the fact that numerous studies in the literature address biped robotics, they are largely limited to inspections and rescue applications. In addition, none of the previous work in biped robotics targets glass facade cleaning, which presents significant opportunities for research and development. Our ultimate goal is to develop a glass facade cleaning robot using a biped mechanism capable of crossover from one glass panel to another without any difficulties, with an objective of maximizing its coverage area. In order to attain a working robotic system that can achieve a superior area coverage performance, we adopted a parallel linkage mechanism for the developed platform. The major challenges encountered during the development of our facade cleaning robot were its parallel linkage mechanism design, the assimilation of cleaning modules, and the translation of the theoretical design into a physical prototype. This paper summarizes all these aspects and concludes with experimental results that validate its ability to move from one glass pane to another. This paper is organized as follows. The design and development of the biped facade cleaning robot satisfying the basis strategy is described in Section 2. Section 3 describes the design of the control system to locomote the developed biped robot on the glass surface. It is verified in Section 4 that the developed robot is capable of moving on the glass surface by utilizing the designed trajectory generator.