Learning feedforward controller for a mobile robot vehicle

This paper describes the design and realisation of an on-line learning posetracking controller for a three-wheeled mobile robot vehicle. The controller consists of two components. The first is a constant-gain feedback component, designed on the basis of a second-order model. The second is a learning feedforward component, containing a single-layer neural network, that generates a control contribution on the basis of the desired trajectory of the vehicle. The neural network uses B-spline basis functions, enabling a computationally fast implementation and fast learning. The resulting control system is able to correct for errors due to parameter mismatches and classes of structural errors in the model used for the controller design. After sufficient learning, an existing static gain controller designed on the basis of an extensive model has been outperformed in terms of tracking accuracy

Supplementation with engineered Lactococcus lactis improves the folate status in deficient rats

Objective: The aim of this study was to establish the bioavailability of different folates produced by engineered Lactococcus lactis strains using a rodent depletion-repletion bioassay. Methods: Rats were fed a folate-deficient diet, which produces a reversible subclinical folate deficiency, supplemented with different L lactis cultures that were added as the only source of folate. Three bacterial strains that overexpressed the folC, folKE, or folC + KE genes were used. These strains produce folates with different poly glutamyl tail lengths. The growth response of the rats and the concentration of folates in different organs and blood samples were monitored. Results: The folate produced by the engineered strains was able to compensate the folate depletion in the diet and showed similar bioavailability compared with commercial folic acid that is normally used for food fortification. Folate concentrations in organ and blood samples increased significantly in animals that received the folate-producing strains compared with those that did not receive bacterial supplementation. Hematologic studies also showed that administration of the L towns strains was able to revert a partial megaloblastic anemia caused by folate deficiency. No significant differences were observed in the bioavailability of folates containing different glutamyl tail lengths. Conclusion: To our knowledge, this is the first study that demonstrated that folates produced by engineered lactic acid bacteria represent a bioavailable source of this essential vitamin. (C) 2010 Elsevier Inc. All rights reserved