Reliable fastening and unfastening of bolts and screws within a fusion environment are crucial for maintaining components in fusion machines such as tokamaks or stellarators. Due to the hazardous conditions created by fusion reactions, these tasks must be executed remotely. Force torque sensing is an essential tool for remote maintenance applications, enabling interaction with the machine’s environment. RACE aims to demonstrate the use of this technology and commissioned M5tec to design and implement this remote handling project.

As a tier 1 provider on UKAEA’s Engineering Design Services Framework, M5tec was assigned the task of developing a design to demonstrate the operability of force torque sensors and grippers. A robot cell was designed that includes an interface frame and a KUKA KR60 industrial robot, onto which the force torque sensor and gripper were mounted. The interface frame features a modular design consisting of a structural frame, bolt pick-up station, clearance hole assembly, and nut retention assembly. Furthermore, the cell incorporated additional lighting and an ultra-high-definition camera to document the operations.

To showcase the feasibility of using a force torque sensor for bolting operations, the robot, sensor, and gripper were programmed to retrieve a bolt from the bolt supply station and insert it into a vertical clearance hole on the top of the interface frame. The pre-programmed path of the robot was deliberately misaligned so that the bolt made contact with the face plate surrounding the clearance hole instead of aligning with it. This prompted the sensor feedback to halt the bolt’s advancement and initiate a hole search program. The hole search program moved the bolt in a spiral pattern with a pecking motion until the bolt successfully advanced past the face plate and located the clearance hole.

Once at the full depth of the clearance hole, the robot began to rotate to initiate the threading operation. The torque feedback from the sensor was used to monitor any cross threading and ensure the bolt was inserted correctly and to the required torque. This procedure was then repeated in a horizontal orientation, demonstrating that the system can insert bolts into clearance holes and thread them into nuts in both the vertical and horizontal orientations.

The following services were provided by M5tec:

• Collaborating with UKAEA on the specification and design of the robot cell, offering guidance to reach a suitable solution.
• Design and build of the interface frame and ancillary components
• Design and build of the robot cell including safety system
• Successful integration of the UKAEA-issued components (force torque sensor and gripper).
• Programming the robot, sensor and gripper to perform the bolt insertion operations
• Bringing on third party robotic experts in the delivery of the project, further upskilling the supply chain of UK remote handling technology providers.

The key outcomes of the project include:

• Construction of a robot cell with custom made demonstration hardware for threading M30 bolts into a test workpiece.
• A successful demonstration of the robot force torque sensing techniques to insert the bolts in two orientations.
• Strengthening of partnership between M5tec and UKAEA/RACE.
• The generation of a detailed technical report documenting all findings with video evidence of the trails and demonstrations.

M5tec’s expertise in remote handling and robotics was pivotal in the successful completion of this project. Leveraging our extensive knowledge and experience, we designed and executed the entire project within an impressive timeframe of just five months. Our team demonstrated exceptional skills in integrating advanced force torque sensors and grippers with the KUKA KR60 industrial robot, ensuring precise and reliable operations. The seamless collaboration with UKAEA and the incorporation of third-party robotic experts further underscored our commitment to delivering innovative and high-quality solutions. This project not only highlights M5tec’s technical expertise but also our ability to manage complex engineering challenges efficiently and effectively.