The control problem of trajectory based path following for passenger vehicles is studied. Comprehensive nonlinear vehicle model is utilized for simulation vehicle response during various maneuvers in MATLAB/Simulink. ...The control problem of trajectory based path following for passenger vehicles is studied. Comprehensive nonlinear vehicle model is utilized for simulation vehicle response during various maneuvers in MATLAB/Simulink. In order to follow desired path, a driver model is developed to enhance closed loop driver/vehicle model. Then, linear quadratic regulator(LQR) controller is developed which regulates direct yaw moment and corrective steering angle on wheels. Particle swam optimization(PSO) method is utilized to optimize the LQR controller for various dynamic conditions. Simulation results indicate that, over various maneuvers, side slip angle and lateral acceleration can be reduced by 10% and 15%, respectively, which sustain the vehicle stable. Also, anti-lock brake system is designed for longitudinal dynamics of vehicle to achieve desired slip during braking and accelerating. Proposed comprehensive controller demonstrates that vehicle steerability can increase by about 15% during severe braking by preventing wheel from locking and reducing stopping distance.展开更多
A stochastic optimal control strategy for a slightly sagged cable using support motion in the cable axial direction is proposed. The nonlinear equation of cable motion in plane is derived and reduced to the equations ...A stochastic optimal control strategy for a slightly sagged cable using support motion in the cable axial direction is proposed. The nonlinear equation of cable motion in plane is derived and reduced to the equations for the first two modes of cable vibration by using the Galerkin method. The partially averaged Ito equation for controlled system energy is further derived by applying the stochastic averaging method for quasi-non-integrable Hamiltonian systems. The dynamical programming equation for the controlled system energy with a performance index is established by applying the stochastic dynamical programming principle and a stochastic optimal control law is obtained through solving the dynamical programming equation. A bilinear controller by using the direct method of Lyapunov is introduced. The comparison between the two controllers shows that the proposed stochastic optimal control strategy is superior to the bilinear control strategy in terms of higher control effectiveness and efficiency.展开更多
The biggest challenge in using CRISPR technologies,which limits their widespread application in medicine,is off-target effects.These effects could,in principle,be minimized by ensuring that CRISPR is activated primari...The biggest challenge in using CRISPR technologies,which limits their widespread application in medicine,is off-target effects.These effects could,in principle,be minimized by ensuring that CRISPR is activated primarily in the targeted cells,thereby reducing the likelihood of unintended genetic modifications in non-target tissues.Therefore,the development of a light activatable CRISPR approach to dynamically control gene activation in both space and time would be highly beneficial.A drawback is that the overwhelming majority of recently introduced light activatable CRISPR systems require UV or blue light exposure,severely limiting the penetration depth of light in tissue at which CRISPR can be activated,and,in the case of UV light,raising safety concerns.A small number of systems that activate CRISPR using longer wavelengths are hindered by either slow light activation or issues related to toxicity and biocompatibility of the proposed techniques in humans.To address this,we developed a split-Cas9/dCas9 system in which activation is achieved through a near-infrared photocleavable dimerization complex.This photoactivation method can be safely used in humans in vivo,easily adapted to different split-Cas9/dCas9 systems,and enables rapid,spatially precise light activation across various cell types.展开更多
文摘The control problem of trajectory based path following for passenger vehicles is studied. Comprehensive nonlinear vehicle model is utilized for simulation vehicle response during various maneuvers in MATLAB/Simulink. In order to follow desired path, a driver model is developed to enhance closed loop driver/vehicle model. Then, linear quadratic regulator(LQR) controller is developed which regulates direct yaw moment and corrective steering angle on wheels. Particle swam optimization(PSO) method is utilized to optimize the LQR controller for various dynamic conditions. Simulation results indicate that, over various maneuvers, side slip angle and lateral acceleration can be reduced by 10% and 15%, respectively, which sustain the vehicle stable. Also, anti-lock brake system is designed for longitudinal dynamics of vehicle to achieve desired slip during braking and accelerating. Proposed comprehensive controller demonstrates that vehicle steerability can increase by about 15% during severe braking by preventing wheel from locking and reducing stopping distance.
基金supported by the National Natural Science Foundation of China (11072212,10932009)the Zhejiang Natural Science Foundation of China (7080070)
文摘A stochastic optimal control strategy for a slightly sagged cable using support motion in the cable axial direction is proposed. The nonlinear equation of cable motion in plane is derived and reduced to the equations for the first two modes of cable vibration by using the Galerkin method. The partially averaged Ito equation for controlled system energy is further derived by applying the stochastic averaging method for quasi-non-integrable Hamiltonian systems. The dynamical programming equation for the controlled system energy with a performance index is established by applying the stochastic dynamical programming principle and a stochastic optimal control law is obtained through solving the dynamical programming equation. A bilinear controller by using the direct method of Lyapunov is introduced. The comparison between the two controllers shows that the proposed stochastic optimal control strategy is superior to the bilinear control strategy in terms of higher control effectiveness and efficiency.
基金supported by US National Science Foundation grants EFRI 1830878,CBET 1948722,CBET 2220273,and CBET 2325317US National Institutes of Health grants R01 EB025173,R01 CA228029,R01 CA293050,R01 GM143749,and R21 AG085089.
文摘The biggest challenge in using CRISPR technologies,which limits their widespread application in medicine,is off-target effects.These effects could,in principle,be minimized by ensuring that CRISPR is activated primarily in the targeted cells,thereby reducing the likelihood of unintended genetic modifications in non-target tissues.Therefore,the development of a light activatable CRISPR approach to dynamically control gene activation in both space and time would be highly beneficial.A drawback is that the overwhelming majority of recently introduced light activatable CRISPR systems require UV or blue light exposure,severely limiting the penetration depth of light in tissue at which CRISPR can be activated,and,in the case of UV light,raising safety concerns.A small number of systems that activate CRISPR using longer wavelengths are hindered by either slow light activation or issues related to toxicity and biocompatibility of the proposed techniques in humans.To address this,we developed a split-Cas9/dCas9 system in which activation is achieved through a near-infrared photocleavable dimerization complex.This photoactivation method can be safely used in humans in vivo,easily adapted to different split-Cas9/dCas9 systems,and enables rapid,spatially precise light activation across various cell types.
