Randomized Nonlinear MPC for Uncertain Control-Affine Systems with Bounded Closed-Loop Constraint Violations

2014 ◽  
Vol 47 (3) ◽  
pp. 1649-1654 ◽  
Author(s):  
Xiaojing Zhang ◽  
Sergio Grammatico ◽  
Kostas Margellos ◽  
Paul Goulart ◽  
John Lygeros
2009 ◽  
Vol 1 (3) ◽  
Author(s):  
Chunshi Feng ◽  
Shuang Cong ◽  
Weiwei Shang

In this paper, the kinematic calibration of a planar two-degree-of-freedom redundantly actuated parallel manipulator is studied without any assumption on parameters. A cost function based on closed-loop constraint equations is first formulated. Using plane geometry theory, we analyze the pose transformations that bring infinite solutions and present a kinematic calibration integrated of closed-loop and open-loop methods. In the integrated method, the closed-loop calibration solves all the solutions that fit the constraint equations, and the open-loop calibration guarantees the uniqueness of the solution. In the experiments, differential evolution is applied to compute the solution set, for its advantages in computing multi-optima. Experimental results show that all the parameters involved are calibrated with high accuracy.


Author(s):  
Latchezar L. Ganovski ◽  
Paul Fisette ◽  
Jean-Claude Samin

Abstract The modeling and control of redundantly actuated closed-loop mechanical systems is considered in the present work an illustrated with a planar four-bar mechanism and a 3-D parallel manipulator. A specific trajectory involving singular configurations is generated and then followed using the overactuation. To generate the trajectory, four-degree polynomial functions are considered. The loop constraint equations are solved by means of the Newton-Raphson numerical algorithm. In order to describe the dynamics of the systems, the Lagrange multiplier technique is used. The multipliers are eliminated via the coordinate partitioning method. To overcome the underdetermined state of the system induced by the overactuation, additional equations that represent a specific condition for smoothly passing through the singularities are applied. Further, to control the redundantly actuated mechanisms a feed-forward controller is chosen. The robustness of the controller is investigated through several cases of simulation including random noise applied to the controller input and instantaneous loading.


Author(s):  
A. Doris ◽  
N. van de Wouw ◽  
W. P. M. H. Heemels ◽  
H. Nijmeijer

We consider the disturbance attenuation problem for a class of continuous piecewise affine systems. Hereto, observer-based output-feedback controllers are proposed that render the closed-loop system uniformly convergent. The convergence property ensures, first, stability and, second, the existence of a unique, bounded, globally asymptotically stable steady-state solution for each bounded disturbance. The latter property is key in uniquely specifying closed-loop performance in terms of disturbance attenuation. Because of its importance in engineering practice, the class of harmonic disturbances is studied in particular and performance measures for this class of disturbances are proposed based on so-called generalized frequency response functions for convergent systems. Additionally, the derived control strategy is extended by including conditions that guarantee the satisfaction of a bound on the control input. The effectiveness of the proposed control design strategy is illustrated by the application of the results to an experimental benchmark system being a piecewise affine beam system.


1961 ◽  
Vol 41 (3) ◽  
pp. 245-250 ◽  
Author(s):  
George H. Bornside ◽  
Isidore Cohn
Keyword(s):  

2012 ◽  
Vol 220 (1) ◽  
pp. 3-9 ◽  
Author(s):  
Sandra Sülzenbrück

For the effective use of modern tools, the inherent visuo-motor transformation needs to be mastered. The successful adjustment to and learning of these transformations crucially depends on practice conditions, particularly on the type of visual feedback during practice. Here, a review about empirical research exploring the influence of continuous and terminal visual feedback during practice on the mastery of visuo-motor transformations is provided. Two studies investigating the impact of the type of visual feedback on either direction-dependent visuo-motor gains or the complex visuo-motor transformation of a virtual two-sided lever are presented in more detail. The findings of these studies indicate that the continuous availability of visual feedback supports performance when closed-loop control is possible, but impairs performance when visual input is no longer available. Different approaches to explain these performance differences due to the type of visual feedback during practice are considered. For example, these differences could reflect a process of re-optimization of motor planning in a novel environment or represent effects of the specificity of practice. Furthermore, differences in the allocation of attention during movements with terminal and continuous visual feedback could account for the observed differences.


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