Stanford School of Engineering & Doerr School of Sustainability
ENGINEERING Civil & Environmental Engineering
Center for Integrated Facility Engineering

Report "Obayashi Automated Crane"

Introduction to the robot and the construction project

Obayashi is a leading general contractor in Japan. The Autonomous Crane (Fig.1.) is the latest technological development in Obayashi’s automation efforts. The motivations for this robotic technology are to: 

  • contribute to the development of a fully automated job site with information transfer between different systems and machines on and off-site,  
  • alleviate labor shortages, by reducing the need for human labor on the job,
  • make the crane operator’s role more attractive to younger workers,
  • increase crane efficiency,
  • and provide safety benefits to crane labor crews. 

The autonomous crane is used in the Kawakami Dam Construction Work project located in Iga City, Mie Prefecture, Japan (Fig.2.). This project spans from September 2017 to March 2023. and involves the construction of a 310 million cubic meter capacity heavy concrete dam, Obayashi Corporation, Sato Kogyo, and JDC Corporation are collaborating on this project. 

Fig.1. Obayashi Autonomous Crane
Fig.1. Obayashi Autonomous Crane
Fig.2. Location of the Kawakami Dam project
Fig.2. Location of the Kawakami Dam project

POP analysis

  • Product: Few modifications have been made to the mechanics of the crane, including LiDAR sensors, AI Autonomous System, and a suspended load direction control device called Skyjuster, so the robot has the same mechanical constraints (mobility, transport radius, lifting speed, etc.) as the manually-controlled crane.
  • Organization: For the manually controlled system, three organizations communicate for each lifting operation. The sub-contractor in charge of load lifting (e.g. the concrete sub-contractor) has to coordinate with the crane operator (also sub-contracted) and Obayashi, the General Contractor, for each operation. With the autonomous crane, Obayashi trained internal staff to take up the crane operator role. Hence, the number of organizations would decrease from 3 to 2 per lifting operation. 
  • Process: For the manual process, the ground crew needs to communicate with the crane operator through hand signals and voice signals to adjust the position of the load, which is also the most time-consuming part of the entire process. In contrast, the autonomous cranes could simplify this part of the work for crane operators with the Skyjuster technology that ensures the precision of the ​​suspended load direction control device.

 

SQSC analysis

  • Safety: By using the robot, we estimated a 100% reduction in “struck by crane” incidents due to the AI + LIDAR system. Furthermore, the crane operator works remotely and can take breaks while the crane conducts a lifting operation.
  • Quality: The automated crane has a precision of 0.1 degrees in rotation by using sensors installed. A skilled and experienced crane operator could achieve similar accuracy through joystick manipulation. 
  • Schedule: Though the robot needs 1 hour/month increase in BIM coordination meetings, it saves time by improving movement and winding efficiency. Also, the operator was confident in remotely monitoring more than one crane at the same time. Overall, it could achieve ~10% decrease in total crane work time, and ~50% decrease in crane monitor hours.
  • Cost: From a project perspective, through the use of robots, the increased efficiency of movement and winding, and the fact that operators can monitor multiple cranes simultaneously could reduce labor costs for crane operators while providing opportunities for operators to increase their income. Meanwhile, as it reduced the settlement cost due to crane-related death, although the upfront cost and monthly service cost exist, using the robot could help to save total cost by ~23%. 

 

Conclusion

In light of safety and labor challenges, the autonomous crane is a robot that adds value to the job site. We recommend the use of the Obayashi Automated Crane for this construction project for applications such as Structural Steel Beam Installation, Precast Concrete Installation, and General Lifting and Rigging Activities. The researchers  identified future work needed to generalize the solution. 

  • The robotic crane needs additional trials on more diverse types of projects to understand the full extent of the robot's benefits and feasible applications, in industries including manufacturing, warehouses, and shipyards.
  • The technology should also be deployed to retrofit a wider array of cranes.
  • Finally, more testing and investment in unstructured applications like concrete pouring is necessary to observe whether the same time savings are seen in more structured applications, such as steel beams.