Parameter Sensitivity Analysis for Design and Control of Tendon Transmissions.
01/1995; pp.241-252 In proceeding of: Experimental Robotics IV, The 4th International Symposium, Stanford, California, USA, June 30 - July 2, 1995
Article: Analysis and optimization of tendinous actuation for biomorphically designed robotic systems[show abstract] [hide abstract]
ABSTRACT: We present a general framework for modeling a class of mechanical systems for robotic manipulation, con-sisting of articulated limbs with redundant tendinous actu-ation and unilateral constraints. Such systems, that include biomorphically designed devices, are regarded as a collec-tion of rigid bodies, interacting through connections that model both joints and contacts with virtual springs. Meth-ods previously developed for the analysis of force distribu-tion in multiple whole-limb manipulation are generalized to this broader class of mechanisms, and are shown to provide a basis for the control of co–contraction and internal forces that guarantee proper operation of the system. In particu-lar, in the presence of constraints such as those due to lim-ited friction between surfaces or object fragility, the choice of tendon tensions is crucial to the success of manipulation. An algorithm is described that allows to evaluate efficiently set–points for the control of tendon actuators that "opti-mally" (in a sense to be described) comply with the given constraints.01/2000; 18.
Article: Control/structure optimization approach for minimum-time reconfiguration of tensegrity systems[show abstract] [hide abstract]
ABSTRACT: For a new class of tendon-driven robotic systems that is generalized to include tensegrity structures, this paper focuses on a method to jointly optimize the control law and the structural complexity for a given point-to-point maneuvering task. By fixing external geometry, the number of identical stages within the domain is varied until a minimal mass design is achieved. For the deployment phase, a new method is introduced which determines the tendon force inputs from a set of admissible, non-saturating inputs, that will reconfigure each kinematically invertible unit along its own path in minimum time. The approach utilizes the existence conditions and solution of a linear algebra problem that describe how the set of admissible tendon forces is mapped onto the set of path-dependent torques. Since this mapping is not one-to-one, free parameters in the control law always exist. An infinity-norm minimization with respect to these free parameters is responsible for saturation avoidance. In addition to the required time to deploy, the expended control energy during the post-movement phase is also minimized with respect to the total number of stages. Conditions under which these independent minimizations yield the same robot illustrate the importance of considering control/structure interaction within this new robotics paradigm.
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