This paper proposes a cooperative game-based actuator fault-tolerant control strategy for a four-wheel independent drive electric vehicle with an active front steering system. For achieving fault-tolerant control and targets cooperation, a two-dimensional game strategy is proposed to balance the stability and economy. The first-dimensional game is utilized to determine the dominant control target of the actuator, then the second-dimensional game is employed to assign the fault-tolerant control task for the remaining healthy actuators. The two dimensions are integrated based on the linear quadratic differential game theory, and a hybrid weighted Pareto frontier is thus established. A Shapley value based weight calculation method is proposed to obtain a set of fair and unique weights according to the importance of each player, which makes the solution of the optimal control problem more easily obtained. The effectiveness and real-time performance of the control strategy are tested under different scenarios. The simulation results demonstrate that the proposed strategy can balance the stability and economy well, outperforms the traditional method in terms of target tracking performance. For special case, the response of the yaw rate could be improved up to 39.83% comparing to that of the linear quadratic regulator method.
Hydrogenobyrinic acid, a modified tetrapyrrole composed
of eight
five-carbon compounds, is a key intermediate and central framework
of vitamin B12. Synthesis of hydrogenobyrinic acid requires
eight S-adenosyl-methionine working as the methyl
group donor catalyzed by 12 enzymes including six methyltransferases,
causing the great shortage of S-adenosyl-methionine
and accumulation of S-adenosyl-homocysteine, which
is uneconomic and unsustainable for the cascade reaction. Here, we
report a cell-free synthetic system for producing hydrogenobyrinic
acid by integrating 12 enzymes using 5-aminolevulininate as a substrate
and develop a novel S-adenosyl-methionine regeneration
system to steadily supply S-adenosyl-methionine and
avoid the accumulated inhibition of S-adenosyl-homocysteine
by consuming a cheaper substrate (l-methionine and polyphosphate).
By combination of the reaction system optimization and S-adenosyl-methionine regeneration, the titer of hydrogenobyrinic
acid was improved from 0.61 to 29.39 mg/L in a 12 h reaction period,
representing an increase of 48.18-fold, raising an efficient and rapidly
evolutional alternative method to produce high-value-added compounds
and intermediate products.
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