Authors:
Ronald G.K.M. Aarts
1
;
Ben J.B. Jonker
1
and
Rob R. Waiboer
2
Affiliations:
1
University of Twente, Netherlands
;
2
Netherlands Institute for Metals Research, Netherlands
Keyword(s):
Realistic closed-loop trajectory simulation, Industrial robot, Perturbation method, Friction modelling.
Related
Ontology
Subjects/Areas/Topics:
Informatics in Control, Automation and Robotics
;
Modeling, Simulation and Architectures
;
Robotics and Automation
Abstract:
This paper presents a realistic dynamic simulation of the closed-loop tip motion of a rigid-link manipulator with joint friction. The results from two simulation techniques are compared with experimental results. A six-axis industrial Stäubli robot is modelled. The LuGre friction model is used to account both for the sliding and pre-sliding regime. The manipulation task implies transferring a laser spot along a straight line with a trapezoidal velocity profile. Firstly, a non-linear finite element method is used to formulate the dynamic equations of the manipulator mechanism. In a closed-loop simulation the driving torques are generated by the control system. The computed trajectory tracking errors agree well with the experimental results. Unfortunately, the simulation is very time-consuming due to the small time step of the discrete-time controller. Secondly, a perturbation method has been applied. In this method the perturbed motion of the manipulator is modelled as a first-order p
erturbation of the nominal manipulator motion. Friction torques at the actuator joints are introduced at the stage of perturbed dynamics. A substantial reduction of the computer time is achieved without loss of accuracy.
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