# Progress in Construction Robot Path-Planning Algorithms: Review
## 1 Introduction  
The data indicate that the aging population in China significantly impacts the age distribution of construction workers. As workers grow older, many find themselves unable to perform high-intensity physical tasks. This prevalent aging trend in the workforce results in a depletion of human resources and intensifies labor shortages within the industry [1]. In response to the challenges faced by traditional construction practices and to align with contemporary trends, the Ministry of Housing and Urban-Rural Development (Beijing, China), along with other relevant agencies, has advocated for the enhanced utilization of construction robots. This initiative aims to foster the intelligent advancement of the construction sector and facilitate its transformation and upgrading [2]. Currently, robotic technologies find extensive applications across various engineering disciplines, including coal mining [3, 4, 5], agriculture [6, 7], healthcare [8], military [9], and autonomous driving [10]. With the rise of intelligent construction technologies, the integration of construction robots has emerged as a promising avenue for the sector's evolution. Intelligent construction seeks to achieve automation, intelligence, and digitization in production and constructionprocesses, necessitating the use of integrated intelligent equipment such as robots. In recent years, mechanized and automated construction models have been progressively adopted in the industry, leading to the development and deployment of specialized construction robots. These robots are defined as machines capable of executing construction tasks either autonomously or semi-autonomously, following pre-defined programming. By addressing labor shortages, construction robots not only enhance operational efficiency but also improve the quality of work within the construction industry [11; 12]. Compared to industrial robots, the history of construction robots is relatively short. The development of construction robots originated in Japan in the 1970s. In 1982, a fire-resistant material spraying robot (Shimizu Corporation, Tokyo, Japan) developed by the Japanese Shimizu Corporation (Tokyo, Japan) was successfully used on a construction site, marking the world's first construction robot to be successfully applied. From the 1980s to the 1990s, with the development of robotic technology and increased investment from the United States, Europe, and others, the types of construction robots began to diversify and evolve towards automation and intelligence. In the 21 st century, the scope of work for construction robots has expanded, gradually moving from traditional construction and construction fields towards demolition, building maintenance, and other areas. After 2010, the development and application of technologies such as artificial intelligence, machine vision, and 3D printing significantly advanced the field of construction robotics. This progress led to the emergence of new types of construction robots capable of autonomous navigation, decision-making, and precise construction tasks--for example, the exterior wall cleaning robot called GEKKO (GEKKO GmbH, Ostfildern, Germany) by the (Ostfildern, Germany). The development and application of these construction robots have made it possible for humans to be relieved from hard and dangerous construction work. Figure 1 shows the development process of construction robots. Construction robots are divided into two categories: construction robots in the field of civil engineering (CRCE) and construction robots in the field of building construction (CRBE). The primary difference between the two lies in their construction scenarios. CRCE is mainly used for infrastructure projects, such as roads, bridges, tunnels, and dams. In contrast, CRBE is applied to housing construction, including residential buildings, office buildings, and commercial complexes. CRCE typically handles large-scale operations, such as earthmoving, foundation treatment, concrete pouring, and steel structure installation.