Inverse Dynamics of Flexible Manipulators
2010 (English)Report (Other academic)
High performance robot manipulators, in terms of cycle time and accuracy, require well designed control methods, based on accurate dynamic models. Robot manipulators are traditionally described by the ﬂexible joint model or the ﬂexible link model. These models only consider elasticity in the rotational direction. When these models are used for control or simulation, the accuracy can be limited due to the model simpliﬁcations, since a real manipulator has a distributed ﬂexibility inall directions. This work investigates different methods for the inverse dynamics of a more general manipulator model, called the extended ﬂexible joint model. The inverse dynamics solution is needed for feedforward control, which is often used for high-precision robot manipulator control.
The inverse dynamics of the extended ﬂexible joint model can be computed as the solution of a high-index differential algebraic equation (DAE). One method is to solve the discretized DAE using a constant stepsize constant-order backwards differentiation formula (BDF). This work shows that there is only a small difference between solving theoriginal high-index DAE and the index-reduced DAE. It is also concluded that scaling of the algebraic equations and their derivatives is important.
The inverse dynamics can be solved as an initial-value problem if the zero dynamics of the system is stable, i.e., minimum phase. For unstable zero dynamics, an optimization approach based on the discretized DAE is suggested. An optimization method, using a continuous DAE formulation, is also suggested and evaluated. The solvers are illustrated by simulation, using a manipulator with two actuators and ﬁve degrees-of-freedom.
Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2010. , 9 p.
LiTH-ISY-R, ISSN 1400-3902 ; 2939
Manipulator- -Control--Differential algebraic equation--Flexible multibody dynamics--Non-minimum phase--Inverse dynamics
IdentifiersURN: urn:nbn:se:liu:diva-97549ISRN: LiTH-ISY-R-2939OAI: oai:DiVA.org:liu-97549DiVA: diva2:648394
FunderSwedish Research Council