PARAMETER-IDENTIFICATION OF A SEMIFLEXIBLE KINEMATIC MODEL FOR SERIALMANIPULATORS

Structural and control flexibilities affect the absolute precision of serial manipulators. A semi-flexible kinematic model is developed, to improve the absolute static precision. It expands the solid body model by incorporating a spring effect for each joint and a beam effect for each link. The identifiability of the added parameters and the effect of measurement noise are explored on a R4 robot. It requires efforts and pose errors to be known in the tool frame only. Simulation results show that identification of some of the parameters is sensitive to me asurement noise on forces and pose. In fact, joint flexibility displac ement and beam flexion that occur in the same plane are difficult to d issociate in noisy condition. However, a subset of the original parame ters can be defined leading to a model that can be more accurately ide ntified when measurement noise is present. In simulation, precompensat ion is used in an inverse semi-flexible model that results in a 98% de crease of pose error compared to the rigid body inverse geometric mode l.