Investigation of the impact of various robot properties on a twin Robot-CT system

Robot-CT is drawing great attention for its potential to support highly flexible scan trajectories and various scan modes with a single system. However, the quality of CT reconstruction largely depends on accurate knowledge of the scan geometry, i.e. position and orientation of the source and the detector. This imposes major challenges on current serial industrial robots. In order to realistically assess the impact of various robot characteristics on the Robot-CT reconstruction quality and to facilitate the development of a dedicated calibration method, this paper elaborates on a set of simulations based on the performance evaluation of an ABB industrial robot. Simulation results reveal that: (a) synchronous error motions of the twin robots can partially compensate for the robot errors; (b) offline calibration is a possible way to implement high accuracy Robot-CT due to the excellent repeatability of current industrial robots; (c) both robot positioning and orientation errors need to be compensated for to get a high quality reconstruction; (d) compensating for only the relative error cannot improve the final reconstruction quality: absolute positioning and orientation errors need to be measured and compensated for. External sensors or radiograph based absolute geometry calibration are needed to improve the reconstruction quality.