Fengjun Yan

Hybrid Electric Vehicle Model Predictive Control Torque-Split Strategy Incorporating Engine Transient Characteristics

This paper presents a model predictive control (MPC) torque-split strategy that incorporates diesel engine transient characteristics for parallel hybrid electric vehicle (HEV) powertrains. To improve HEV fuel efficiency, torque split between the diesel engine and the electric motor and the decision as to whether the engine should be on or off are important. For HEV applications where the engines experience frequent transient operations, including start-stop, the effect of the engine transient characteristics on the overall HEV powertrain fuel economy becomes more pronounced. In this paper, by incorporating an experimentally validated real-time-capable transient diesel-engine model into the MPC torque-split method, the engine transient characteristics can be well reflected on the HEV powertrain supervisory control decisions. Simulation studies based on an HEV model with actual system parameters and an experimentally validated diesel-engine model indicate that the proposed MPC supervisory strategy considering diesel engine transient characteristics possesses superior equivalent fuel efficiency while maintaining HEV driving performance.

Composite Nonlinear Feedback Control for Path Following of Four-Wheel Independently Actuated Autonomous Ground Vehicles

This paper investigates the path-following control problem for four-wheel independently actuated autonomous ground vehicles through integrated control of active front-wheel steering and direct yaw-moment control. A modified composite nonlinear feedback strategy is proposed to improve the transient performance and eliminate the steady-state errors in path-following control considering the tire force saturations, in the presence of the time-varying road curvature for the desired path. Path following is achieved through vehicle lateral and yaw control, i.e., the lateral velocity and yaw rate are simultaneously controlled to track their respective desired values, where the desired yaw rate is generated according to the path-following demand. CarSim-Simulink joint simulation results indicate that the proposed controller can effectively improve the transient response performance, inhibit the overshoots, and eliminate the steady-state errors in path following within the tire force saturation limits.

Should the Desired Heading in Path Following of Autonomous Vehicles be the Tangent Direction of the Desired Path

The path-following problem for autonomous vehicles is investigated in this paper. The desired vehicle heading is commonly chosen as the tangent direction on the desired path. This paper points out that the traditional definition of the desired heading may deteriorate the path-following performance, particularly when the vehicle is tracking a path with large curvature. That is because the sideslip angle control and the yaw rate control are conflicting in the presence of sliding effects, and the sideslip angle does not equal to zero when the vehicle is tracking a curve path. This paper further provides an amendment to the definition of the desired heading, which realizes a more accurate path-following maneuver. In the controller design phase, backstepping is used to generate the required yaw rate, and an LQR controller is adopted to obtain the optimal active front steering input. The CarSim-Simulink joint simulation verifies the reasonability of the amendment to the desired heading.

Output Constraint Control on Path Following of Four-Wheel Independently Actuated Autonomous Ground Vehicles

The path-following problem for four-wheel independently actuated autonomous ground vehicles is investigated in this paper. A novel output constraint controller is proposed to deal with the lateral offset control in path following and maintain the vehicle lateral stability in the presence of tire sliding effects. The innovations of this work lie in the following two aspects: 1) A novel output constraint control strategy, namely, the hyperbolic projection method, is proposed to strictly bound the lateral offset to prevent the vehicle from transgressing the safety bound in path following; 2) an adaptive and robust linear quadratic regulator controller is adopted to obtain the optimal active front-wheel steering and direct yaw-moment control inputs with vehicle lateral stability consideration and to eliminate the effect of parameter uncertainties. CarSim-Simulink joint simulation results indicate that the proposed controller can compactly bound the lateral offset to avoid transgressing the safe boundary during path following, particularly in extreme driving conditions, in the presence of tire sliding effects and system uncertainties.

Non-equilibrium transient trajectory shaping control via multiple Barrier Lyapunov Functions for a class of nonlinear systems

This paper presents a non-equilibrium transient trajectory shaping (NETTS) control technique based on a set of Barrier Lyapunov Functions for single-input-single-output strict feedback nonlinear systems. The trajectory shapes of the system outputs or tracking errors during the course of convergence to the equilibrium points are important for some physical systems (e.g. some hybrid systems) where reference signals frequently jump. A smooth trajectory shaping control law consisting of a unidirectional switching mechanism and a control signal continuous approximation method is proposed to ascertain that the system tracking error transient trajectory travels within a shaped-boundary while approaching zero. A numerical example is utilized to show the performance of the proposed NETTS control.

Robust

This paper presents a robust H∞ path following control strategy for autonomous ground vehicles with delays and data dropouts. The state measurements and signal transmissions usually suffer from inevitable delays and data packet dropouts, which may degrade the control performance or even deteriorate the system stability. A robust H∞ state-feedback controller is proposed to achieve the path following and vehicle lateral control simultaneously. A generalized delay representation is formulated to include the delays and data dropouts in the measurement and transmission. The uncertainties of the tire cornering stiffnesses and the external disturbances are also considered to enhance the robustness of the proposed controller. Two simulation cases are presented with a high-fidelity and full-car model based on the CarSim-Simulink joint platform, and the results verify the effectiveness and robustness of the proposed control approach.

H_{\infty}

This paper presents a method to control dual loop EGR air-path systems for Diesel engines running advanced combustion modes. Considering the different time scales (fast and slow) dynamics of high pressure loop EGR (HPL-EGR) and low pressure loop EGR (LPL-EGR), a decomposition control method for a singularly perturbed system was utilized to achieve systematic air-path control, including the control of temperature, pressure, and oxygen fraction in intake manifold. Variable geometry turbocharger (VGT) was used to control the pressure before a high-pressure throttle (HP-Throttle) valve to accommodate the constraints of other actuators, such as dual-loop EGR and HP-Throttle. Effectiveness of such a control methodology was shown by simulation results based on a high-fidelity GT-Power Diesel engine model.

Path Following Control for Autonomous Ground Vehicles With Delay and Data Dropout

This article describes the development and experimental validation of a control-oriented, real-time capable, Diesel engine instantaneous fuel consumption and brake torque model under warmed-up conditions with only two inputs: torque request and the engine speed and no other measurements. Such a model, with the capability of reliably and computationally efficiently estimating the aforementioned variables at both steady-state and transient engine-operating conditions, can be utilized in the context of real-time control and optimization of hybrid power train systems. Although Diesel engine dynamics are highly non-linear and very complex, by considering the Diesel engine and its control system, that is, engine control unit together as an entity, it becomes possible to predict the engine instantaneous fuel consumption and torque based on only those two inputs. A synergy between different modelling methodologies including physically based grey-box and data-driven black-box approaches were integrated in the Diesel engine model. The fuelling and torque predictions have been validated by means of experimental data from a medium-duty Diesel engine at both steady-state and transient operations, including engine start-ups and shutdowns.

Control of dual loop EGR air-path systems for advanced combustion diesel engines by a singular perturbation methodology

Abstract The paper presents a vehicle lateral-plane motion stability control approach for four-wheel independently actuated (FWIA) electric ground vehicles considering the tire force saturations. In order to deal with the possible modeling inaccuracies and parametric uncertainties, a linear parameter-varying (LPV) based robust H ∞ controller is designed to yield the desired external yaw moment. The lower-level controller operates the four in-wheel (or hub) motors such as the required control efforts can be satisfied. An analytical method without using the numerical-optimization based control allocation algorithms is given to distribute the higher-level control efforts. The tire force constraints are also explicitly considered in the control allocation design. Simulation results based on a high-fidelity, CarSim, full-vehicle model show the effectiveness of the control approach.

Development and experimental validation of a control-oriented Diesel engine model for fuel consumption and brake torque predictions

This paper investigates the yaw control issue for in-wheel-motor (IWM) electric ground vehicles (EGVs) based on the differential steering in the presence of the complete failure of the active front-wheel steering. Differential steering is an emerging steering mechanism, generated from the differential torque between the left and right wheels in IWM EGVs. In case that the regular steering system is defective, differential steering can be utilized to act as the sole steering power, and thus avoid dangerous consequences for vehicles. For this purpose, a robust H ∞ output-feedback controller based on differential steering is designed to achieve yaw stabilization, considering that the desired steering angle is uncertain and hard to obtain. Parameter uncertainties for the cornering stiffnesses and the external disturbances are considered to make vehicle robust to different driving conditions. CarSim-Simulink joint simulation results based on a high-fidelity and full-car model verify the effectiveness of the proposed controller to guarantee the equal vehicle handling and stability.