A new force calculation algorithm for tendon-based parallel manipulators

Abstract

Completely and redundantly restraint tendon-based Stewart platforms demand for an appropriate distribution of tendon forces to control the platform on a given trajectory. Thus, position control has to be extended by a tendon force controller which generates continuous and feasible force values. The computation of such force distributions can be formulated as a constrained optimization problem. Solving the problem is numerically expensive and requires an algorithm which is capable to be integrated into a realtime environment. In this paper, a new algorithm for tendon force distribution calculations capable for usage on a realtime system is proposed.

On the control of the KNTU CDRPM: A cable driven redundant parallel manipulator

“…The second equality constraint assures that the joint space forces, τ are the right projection of the cartesian force F. Other optimization techniques can be used to find the actuator forces projected from, F which can minimize a user defined cost function [6]. The block diagram of IDC in the workspace coordinate is given in figure 3.…”

“…In this case m = n +2 cables are used in order to move the redundant actuated endeffector in an n-dimensional space. Redundancy resolution is needed to assure tension force existence along each cable, however, this is usually computationally expensive [6]. The control algorithms developed for serial counterparts to parallel manipulators with redundant actuation in [7].…”

Wire Robot Suspension Systems for Wind Tunnels

“…Note, that this implementation cannot be used for realtime control since the worst-case run-time in each control cycle cannot be guaranteed a priori. Several approaches are known to handle this problem (Borgstrom et al, 2009;Bruckmann, Mikelsons, Brandt, Hiller & Schramm, 2008a;Bruckmann et al, 2007b;Bruckmann, Pott, Franitza & Hiller, 2006;Ebert-Uphoff & Voglewede, 2004;Fattah & Agrawal, 2005;Oh & Agrawal, 2005;Verhoeven, 2004). In this application, a force minimizing algorithm for realtime force distribution will be implemented, using a geometric approach (Bruckmann, 2010;Bruckmann et al, 2009;Mikelsons et al, 2008).…”

Integrated controller for an over-constrained cable driven parallel manipulator: KNTU CDRPM

“…Other optimization techniques can be used to find the actuator forces projected from, F which can minimize another user defined cost function [8].…”

“…In this case m = n + 2 cables are proposed to be used in order to dextrously move the redundant actuated end-effector in an n-dimensional space [7]. Redundancy resolution is needed to assure tension force along each cable, however, this is usually computationally expensive [8]. The KNTU CDRPM uses a novel design to achieve high stiffness, accurate positioning for high-speed maneuvers.…”