  The paper proposes a novel calibration approach for the Orthoglide-type
mechanisms based on observations of the manipulator leg parallelism during
motions between the prespecified test postures. It employs a low-cost measuring
system composed of standard comparator indicators attached to the universal
magnetic stands. They are sequentially used for measuring the deviation of the
relevant leg location while the manipulator moves the TCP along the Cartesian
axes. Using the measured differences, the developed algorithm estimates the
joint offsets that are treated as the most essential parameters to be adjusted.
The sensitivity of the measurement methods and the calibration accuracy are
also studied. Experimental results are presented that demonstrate validity of
the proposed calibration technique.
