High Efficient Dynamics Calculation Approach for Computed-Force Control of Robots with Parallel Structures

Practical Model-based and Robust Control of Parallel Manipulators Using Passivity and Sliding Mode Theory

“…This is due to the fact, that we consciously limited the switching control to the friction model. The related part A f is very simple to obtain by 36 additions and 54 multiplications (Abdellatif et al, 2005). Extending the switching control to the rigidbody part is not very efficient, since the rigid-body model requires about twenty times more computational effort.…”

“…The core of the scheme consists in the feedforward compensation of the inverse dynamics. Such type of compensation is preferable then the feedback one, since the latter requires the measurement or at least the precise knowledge of the endeffector's pose, translational and angular velocities, which is not easy to manage without additional and expensive sensors (Abdellatif and Heimann, 2007;Abdellatif et al, 2005;Burdet et al, 2000;Kim et al, 2005;Wang and Ghorbel, 2006). The feedback controllers of the single actuators are kept linear and simple to avoid additional computational effort.…”

“…As it has been derived and deeply discussed in former publications (see e.g. (Abdellatif and Heimann, 2007;Abdellatif et al, 2005)) the dynamics model used for the feedforward controller u C contains 24 minimal parameters. The rigid body model part corresponds to a set of www.intechopen.com 10 minimal parameters p. As given by the modeling approach (33), the friction of each of the 6 actuators j is modeled by a dry friction coefficient f 1 j and a viscous dumping coefficient f 2 j .…”

“…The experimental comparison focuses on the two proposed schemes: the passivity based approach presented in section 3, which is denoted in the following by (P-FF) and the scheme with additional Sliding mode control (P-SM). Additionally, both proposed schemes are compared to the classic feedforward computed-force technique (CF-FF), that consists in forwarding the dynamic model by keeping the actuators controlled by standard PID (or PD) controllers (see Abdellatif et al (2005)). The common control parameters for P-FF and P-SM are set equal for a meaningful comparison.…”

Singularity-Free Dynamics Modeling and Control of Parallel Manipulators with Actuation Redundancy

“…The basis for model-based control are the motion equations governing the PKM dynamics. Aiming on an efficient formulation applicable in real-time, the motion equations are commonly derived in terms of a minimum number of generalized coordinates that constitute a (local) parameterization of the configuration space Abdellatif et al (2005); Cheng et al (2003); Müller (2005); Nakamura & Ghodoussi (1989); Yi et al (1989). A well-known problem of this formulation is that these minimal coordinates are usually not valid on all of the configuration space, and configurations where the coordinates become invalid are called parameterization singularities.…”