ADAPTIVE FUZZY‐BASED MIXED H2/H∞ TRACKING CONTROL DESIGN IN UNCERTAIN ROBOTIC SYSTEMS

In this study, an adaptive fuzzy‐based mixed H₂/H_∞ tracking control design is developed in robotic systems under unknown or uncertain plant parameters and external disturbances. The mixed H₂/H_∞ control design has the advantage of both H₂ optimal control performance and H_∞ robust control performance and the fuzzy adaptive control scheme is used to compensate for the plant uncertainties. By virtue of the skew‐symmetric property in the robotic systems and adequate choice of state variable transformation, sufficient conditions are developed for the adaptive fuzzy‐based mixed H₂/H_∞ tracking control problems in terms of a pair of coupled algebraic equations instead of a pair of coupled differential equations. The proposed methods are simple and the coupled algebraic equations can be solved analytically. Simulation results indicate that the desired performance of the proposed adaptive fuzzy‐based mixed H₂/H_∞ tracking control schemes for the uncertain robotic systems can be achieved.     

Metabolism of glucose during ripening of detached tomato fruit

Detached tomato fruit at four stages of ripeness were injected with D-[U-¹⁴C]-glucose. After 72 h the overall metabolism of the labelled glucose and the production of ¹⁴CO₂ were greatest in red fruit and least in over-ripe fruit. Labelled carbon was incorporated into the neutral, basic and acidic fractions of fruit at all stages of ripeness. Labelling of free fructose occurred; this was most marked in mature green and green/yellow fruit and declined during subsequent ripening. Incorporation of ¹⁴C into sucrose was observed, and this increased with ripening although there was a decrease in total (free and combined) fructose labelling. The results suggest that the sucrose synthesis takes place through the action of sucrose phosphate synthetase rather than sucrose synthetase.