Abstract
To solve structures of biomacromolecules is important for structure-based drug design as well as understanding of various biological processes. X-ray crystallography is one of the most popular methods for structure analysis of protein in atomic resolution. Sample exchange robots have been developed and implemented to protein crystallography beamlines in Photon Factory, KEK, for higher efficient experiments, remote-controlled experiments, and fully-automated experiments. In this paper, we proposed using a force and torque sensor installed at the sample exchange robot for stable operation. The sensor records various parameters of the robots' status when the tongs access sample cassettes in a liquid nitrogen Dewar. Distorted load distribution is caused by inclination of the cassette, miscalculation of the center of the cassette, mis-setting of the robot parameters, and other causes. In order to assure stable operation, the robots are appropriately re-calibrated according to the load distribution information.
