Inter-relationship between approximate dynamic inversion and MRAC augmented with proportional-integral controller

Approximate Dynamic Inversion (ADI) is basically an approximation of exact dynamic inversionor feedback linearisation, which converts a nonlinear system to an equivalent linear structure.This method can be widely applied for controlling minimum phase, nonaffine-in-control systems.For applying the ADI method, a fast dynamic subsystem for deriving explicit inversion of thenonaffine equation is required. With full state feedback, ADI may be expressed in the same way asa Proportional Integral (PI) controller with only knowledge of the sign of control effectiveness andalso without any approximation. The Model Reference Adaptive Controller (MRAC) augmentedwith the PI method is an adaptive control technique where the PI parameters are updated/tunedas per the control methodology based on the MRAC-Massachusetts Institute of Technology (MIT)rule so that the plant is capable to follow the reference model. The main objective of this paperis to find the relationship between ADI and MRAC augmented with a PI controller.

Fault tolerant control in an unmanned bicycle robot via sliding mode theory

In this work,a new active fault tolerant control(FTC)is developed for an unmanned bicycle robot based on an integration between a sliding mode control(SMC),fault detection(FD),and fault estimation(FE)via a residual signal.A sliding surface in accordance with the fault tolerant sliding mode control(FTSMC)is designed for the bicycle robot to get multiple exciting features such as fast transient response with finite time convergence,small overshoot and quick stabilisation in the presence of an actuator fault.To obtain an effective performance for the FTSMC,a fault estimation system is employed and in order to attain estimation,an extended Kalman filter(EKF)as an estimator and a change detection algorithm called cumulative sum(CUSUM)as a residual evaluation function are developed.The innovative features of the proposed approach,that is FTSMC,are verified when compared with the other up‐to‐date control techniques like fault tolerant model‐based predictive control with feedback linearisation(FTMPC+FBL)and fault tolerant linear quadratic regulator with feedback linearisation(FTLQR+FBL)on an unmanned bicycle robot.

Integrated control of highway traffic flow

Several efforts have been made during recent years on the control of traffic flow using ramp metering,variable speed limit and lane change control.Most of these techniques reported significant traffic mobility improvements in macroscopic simulations,which cannot be confirmed in some microscopic simulation cases.We demonstrate that the lack of travel time improvement is due to the forced lane changes at the bottleneck which introduce a capacity drop.In this paper,a lane change controller is proposed which provides lane change recommendations to avoid the capacity drop.Combined with the lane change control,a feedback linearisation variable speed limit controller which maintains the bottleneck flow at the maximum level and coordinates with ramp metering controllers is proposed.The integrated VSL,RM and LC controller can improve system performance,manage the ramp queues and maintain the fairness between mainline and on-ramp flows.Microscopic simulations show consistent improvements under different scenarios.