Elasto-geometrical modelling of closed-loop industrial robots used for machining applications

Abstract

This paper presents the elasto-geometrical modelling of an industrial robot manipulator whose structure includes a closed-loop mechanism. This modelling is done for sensitivity studies and calibration purposes since the robot is involved in machining operations that require a high level of quasi static positioning accuracy. The kinematics of the machine is described first then the systematic approach that is proposed to calculate the elastic modelling of its architecture is presented. Simulations and experiments are presented next in order to evaluate the limitations and benefits of the proposed modelling approach.

A Systematic Procedure for the Elastodynamic Modeling and Identification of Robot Manipulators

“…Consequently shearing action can be neglected and the Euler-Bernoulli type beams can be used assuming small deformations. Thus, one can use the same segmentation as implemented in static cases presented in [32]- [34]. A body Ci is segmented into ni beam elements Bi,j and 2ni node elements.…”

A Process/Machine coupling approach: Application to Robotized Incremental Sheet Forming

“…To overcome the difficulties related to the previous approaches, one solution is based on realistic parametric models of machines and robots to predict the elastic deformations. The methodologies proposed in the literature are based either on lumped-parameter model in Dumas et al [2011] or more realistic Finite Element models as in Marie and Maurine [2008]. Since outputs of these models are TCP pose errors, the term elasto-geometrical model is used.…”

An improved kinematic model for calibration of serial robots having closed-chain mechanisms

“…[8]. To begin with, simulated dimensional and angular errors in the range of ±4 × 10 −3 m and ±4 × 10 −3 rad were added to the nominal robot parameters.…”

“…Email: m.h.to@cranfield.ac.uk chains, i.e., the parallelogram mechanism ( Fig. A similar approach was proposed in the work of Marie et.al., 8 where the solution was further differentiated to obtain the loops' error model. When errors in the closed-loop actuating elements are considered in kinematic calibration of these robots, parameter redundancies are unavoidable due to the closure constraints imposed by the loops, and hence, the modeling conventions for open-loop structures introduced earlier cannot be employed directly.…”

“…To continue using them, it is required to resolve the constraint equations explicitly and merge the result with the existing manipulator's global model. [8] 7 considered a degenerated parallelogram, a planar four-bar linkage, of which the position constraints were mathematically solved for its passive joint angles with respect to actuated joint angles and actual link lengths.…”