LINE-OF-SIGHT BASED 3D LOCALIZATION OF PARALLEL KINEMATIC MECHANISMS

Autonomous robots (manipulators or vehicles) may accumulate significant errors during their long-range motion to a desired position and orientation (pose). These errors, however, can be compensated for by subsequent local, short-range corrective actions to within random noise levels of the system. This paper presents a generic localization method for high-precision parallel kinematic mechanisms (PKMs) in order to allow them to accurately achieve their desired poses. The proposed method employs a novel non-contact spatial sensing technique combined with an iterative pose-correction procedure. The proposed sensing technique is based on the use of multiple spatial lines-of-sights (LOSs) emanating from a single source and 'hitting' a planar position sensitive detector (PSD) placed on the PKM's platform. Using the positional feedback provided by the PSD, the instantaneous actual pose of the platform is accurately estimated. A pose-correction method is subsequently invoked to iteratively guide the platform to its desired location within noise levels. Extensive simulations were carried out to illustrate the effectiveness of the proposed localization method for a spatial PKM being developed in our laboratory.