Sliding mode speed auto-regulation technique for robotic tracking

FABRICIO GARELLI; LUIS GRACIA; ANTONIO SALA; PEDRO ALBERTOS

ROBOTICS AND AUTONOMOUS SYSTEMS

ELSEVIER SCIENCE BV

Año: 2011 vol. 59 p. 519 - 529

0921-8890

In advanced industry manufacturing involving robotic operations, the requiredtasks can be frequently formulated in terms of a path or trajectory tracking. In thispaper, an approach based on sliding mode conditioning of a trajectory parametriza-tion is proposed to achieve the greatest tracking speed which is compatible withthe robot input constraints (joint speeds). Some distinctive features of the proposalare that: (1) it is completely independent of the robot parameters, and it does notrequire a-priori knowledge of the desired path either, (2) it avoids on-line computa-tions necessary for conventional analytical methodologies, and (3) it can be easilyadded as a supervisory block to pre-existing trajectory tracking schemes. A sufficientcondition (lower bound on desired tracking speed) for the sliding mode regulation tobe activated is derived, while a chattering amplitude estimation is obtained in termsof the sampling time and a tunable first-order filter bandwidth. The algorithm isevaluated on the freely accesible 6R robot model PUMA-560, for which a trajectorypassing through a wrist singularity is considered to show the effectiveness of theproposal under hard tracking conditions.