The asymptotic stabilization problem for a class of nonlinear under-actuated systems is studied and solved. Its solution, together with the back-stepping and the forwarding control design methods, is exploited in the control of the nonlinear lateral dynamics of a vehicle. Even though the theoretical studies of the lateral control of autonomous vehicles are traditionally applied to lane keeping cases, the results can be applied to broader range of areas, such as lane changing cases. The comparison between the performances of the closed-loop systems with the given controller and a typical human driver is given and demonstrates the speediness and the effectiveness of the feedback controller.
Chemical investigation of the twigs of Cryptocarya impressinervia yielded 23 known compounds including 8 lignans, 3 phenylpropionates, 1 xanthone, 3 flavonoids, 1 phenylpropanoid, 1 substitued phenol, 1 triterpenoid, 3 sterols and 2 aliphatic compounds. All the compounds was isolated from C. impressinervia for the first time. 9,9'-O-Di-feruloyl-(-)-secoisolariciresinol (1) displayed significant cytotoxic activities on five human cancer cell lines (HL-60, SMMC-7721, A-549, MCF-7 and SW-480), with IC 50 values of 3.58, 4.55, 6.39, 5.09 and 4.80 μM, respectively. Rhusemialin A (2) showed significant activity against HL-60 with IC 50 of 3.69 μM. Dihydrosinapyl ferulate (3) displayed moderate cytotoxic activities against five tested human cancer cell lines.To the best of our knowledge, this is the first report on the constituents of C. impressinervia and cytotoxic activities of compounds 1-3 on the tested cancer cell lines.
A fixed-time trajectory tracking control method for uncertain robotic manipulators with input saturation based on reinforcement learning (RL) is studied. The designed reinforcement learning control algorithm is implemented by radial basis function (RBF) neural network, in which the actor neural network is used to generate the control strategy and the critic neural network is used to evaluate the execution cost. A new non-singular fast terminal sliding mode technique is used to ensure the convergence of tracking error in fixed time, and the upper bound of convergence time is estimated. To solve the saturation problem of an actuator, a nonlinear anti-windup compensator is designed to compensate for the saturation effect of the joint torque actuator in real time. Finally, the stability of the closed-loop system based on Lyapunov candidate is analyzed, and the timing convergence of the closed-loop system is proved. Simulation and experimental results show the effectiveness and superiority of the proposed control law.
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