Although several methods have been used to capture the motion of workers at construction sites to improve productivity or safety during construction projects, collecting data by image analysis and discriminating between motions are time-consuming processes. Therefore, it is difficult to use such methods to detect the motion of several workers or over a long time period. The authors applied an accelerometer to capture motion; this apparatus has been used in the health and medical fields. A small, light accelerometer and a simple discrimination program allowed the authors to determine whether a worker was active or inactive based on a threshold of the sum of the signal amplitude areas. Experimental surveys were conducted at construction sites: first, for setting plasterboards for two detached house construction projects and, second, for setting rebar at a large office building site. The findings of this experimental study are as follows. First, an accelerometer can be used in congested construction sites, and data can be obtained continuously. Second, this simple identification of active/inactive workers allows for the measurement of performance and the detection of problems at construction sites. Third, from the data, the hypothesis regarding workers’ tendencies can be tested, that is, how workers’ skill levels may affect the fluctuation of activity intensity. Therefore, in future studies, by increasing the data on workers, researchers could develop methods to improve the performance of workers.

Major prefabricated housing manufacturers started their business in the 1960s and became world‐class large housing companies. This study clarifies the early stages of development in 9 major prefabricated housing manufacturers based on interviews with their in‐house engineers and architectural designers as well as through the analysis of related documents. Early prefabricated houses were developed intensively by a small number of engineers. Various architectural styles and specialists, including foreign architecture, famous architects and academics, affected some aspects of these developments. Furthermore, each of the early prefabricated houses had many unique building system characteristics. Some of these characteristics were modified in the early stages of development, while others still remain today.

Recently, planar pneumatic actuators, known as pouch motors, have gained attention in the fields of soft robotics and Human-Computer Interaction (HCI). However, achieving complex 3D shapes by pouch motors has been hindered by two challenges: (1) the slow operating speed of customized CNC machines, conventionally used for pouch fabrication and (2) the lack of control over the folding angle of individual pouches. To overcome these limitations, (1’) we introduce the use of a laser cutter to fabricate pouch motors. This approach enhances the fabrication process, enabling faster production of the pouch motors. Additionally, (2’) we propose laser-welding patterns that incorporate small barriers to control the folding angle of each pouch. By manipulating the welding patterns, we achieve nearly linear control over the folding angle of the pouches. In this paper, we present the design and fabrication process of laser-welded planar pneumatic actuators and showcase several design examples.

The purpose of the present study is to grasp the situation of construction sites easily by distinguishing the movements of construction workers at construction sites from the accelerometer data attached to their waists. For the construction manager to accurately perceive the active or inactive state of his workers, their movements were classified into three distinct categories: walking, standing, and sitting. We tracked and observed two rebar workers for 5 days at a large building construction site. Their movements were classified by two-axis plots of (1) the difference between the maximum and minimum absolute values and (2) the value of acceleration at each second, and visualized by a heatmap among others for this trial. The results showed that despite the difficulty in distinguishing rebar work without a total body movement while sitting, the accuracy of discrimination was 60–80% in walking and sitting. From this analysis, we were able to identify repetitive tasks and the differences between morning and afternoon tasks. Furthermore, by applying simple visualization, we could concisely represent changes in work intensity over a relatively long period.