The calibration of redundant robots poses challenges to the roboticist
that are not present in the calibration of their nonredundant counterparts.
A motivation for this project is space applications, mainly in light of
the imminent commissioning of the International Space Station. In these
applications, the robot must be calibrated without external sensors, for
a fixed base is not readily available. One basic item to identify in the
context of robot calibration is the offsets in the joint-angle dials, whose
zero does not always coincide with its nominal location. However, when
attempting to identify the joint offsets with the aid of the own robot
encoders, using self-motions, it turns out that, upon fixing the end-effector
(EE) to the robot base, the offsets of the end joints cannot be identified.
A set of measurements is needed in a different EE pose--position and orientation.
We have established identifiable conditions and developed an identification
algorithm that has undergone satisfactory tests in a dual-arm robotic workcell
that is under development, as outlined in this same issue.
Graphics rendering of REDIESTRO 1