• As technology transfer projects with Keyang Electric Machinary, we worked on three sequential projects related to nutrunners as below:

1) Non-impact type nutrunner: in order to avoid applying a brute-force algorithm, which generates a high reaction torque, we developed the turbo-tight algorithm that can significantly reduce the reaction torque applied to a worker's wrist. First, the required energy for tightening a nut is estimated with a nut-bolt friction model, and second, a well-tuned disturbance observer was applied to respond various unknown factors. The final product was supplied to the largest domestic factory.

2) Impact type nutrunner: in order to cope with the highly unpredictable behavior, the overall impact mechanism and electromagnetic system were reconstructed by iteratively matching the actual tightening results and our lumped simulation model. The heuristic control interface was developed and embedded to ease the effort of tuning its performance by the workers.

3) Nutrunner designing tool: as a development tool and educational program for the corporate's workers, we developed a SIMULINK/MATLAB based simulation program that shows the tightening results of a virtual nutrunner built with given parameters.

• I managed the overall project, especially focusing on realizing, embedding, and tuning the developed algorithm.