A finite element approach to the position problems in open-loop variable geometry trusses

The present paper looks at some kinematic and static-equilibrium problems t hat arise with variable-geometry trusses (VGTs). The first part of the pape r looks at the use of active controls in the correction of static deformati ons, the second part at the position problems. The separation between defor mable- and rigid-body displacements makes it possible to consider separatel y the corrections in each component of the structure. VGTs are considered a s open-loop linkages with redundant rigid-body degrees of freedom. Owing to this redundancy, possible solutions to the inverse problem are in general infinite, for which reason it is necessary to use some optimization criteri a. To tackle the problem an optimization procedure with constraints is deve loped for the purpose of minimizing the displacements of the actuators. Sui table use of the constraints allows us to solve the direct position problem using the same optimization procedure. (C) 2000 Elsevier Science B.V. All rights reserved.