In-situ repetitive calibration of microscopic probes maneuvered by holonomic inchworm robot for flexible microscopic operations

In this paper, we describe design and experimental results of repetitive calibration of an holonomic inchworm robot based on an inverse trajectory analysis of a tip of a probe for microscopic operations. The mobile robot has two U-shaped electromagnets and four piezoelectric actuators (PAs) for obtaining 3-degrees-of-freedom (3DoF) motion on well-polished ferromagnetic surfaces. We have proposed the kinematic model to get relationship among four input voltages to PAs and three displacements of the robot at a half step. We have also solved the inverse trajectory analysis of the probe to convert the motion errors of the probe into those of the robot. Moreover, we have proposed repetitive calibration formulas to calibrate 3DoF motion of the probe under a microscope simultaneously. In experiments, we have checked that the proposed formulas are surely working for decreasing the motion errors at straight motion although rotation around the tip is hard to calibrate because of its posture measuring error of an image processor. We discuss compact and flexible microscopic operations.