Changle Xiang

Comprehensive nonlinear modeling and simulation analysis of a tandem ducted fan aircraft

Force and torque generation mechanisms for an unconventional tandem ducted fan aircraft are investigated. Numerical techniques are implemented to obtain quasi-steady thrust, numerical integration of nonlinear equations of motion and trim iteration process, respectively. The comprehensive nonlinear model is derived and simplified to linear approximations at different flight conditions for stability and input-output controllability analysis. Specifically, modal analysis is performed for the vehicle at hover and forward flight. Quantitative input-output controllability analysis is then applied to our plant to find out the fundamental controller-independent limitations and capture what performance can be expected.

Design of hierarchical motion stabilizing controller of tracked mobile robot in three dimensional space

In this paper, stabilizing control of tracked mobile robot in 3-D space was presented. Firstly, models of major modules of TMR were established. Next, to reveal the mechanism of disturbances applied on TMR, two kinds of representative disturbances (slope and general disturbances in yaw motion) were discussed in depth. Consequently, an attempting PID method was employed to compensate the impacts of disturbances and simulation results proved the validity for disturbance incited by slope force, but revealed the lack for general disturbance on yaw motion. Finally, a hierarchical fuzzy controller combined with PID controller was pro posed. In lower level, there were two PID controllers t o compensate the disturbance of slope force, and on top level, the fuzzy logic controller was employed to correct the yaw motion error based on the differences between the model and the real TMR, which was able to guide the TMR maintain on the stable state. Simulation results demonstrated the excellent effectiveness of the newly designed controller.

Modeling and modal responses analysis of an unmanned small-scaled gyroplane

This paper presents aerodynamic analysis of an unmanned small-scaled gyroplane with a rotor having cyclic pitch system. A comprehensive nonlinear model is derived for it which involves force and moment generation mechanism for the flying vehicle. The nonlinear model is linearized with approximations and deduced on a prescribed flight condition. Our gyroplane dynamic modal response is further reconfigured and reveal its differences associations among helicopters and classic autogiros. A study is performed to investigate the effect of forward flight speed and center of gravity (CG) placement on modal response. The results suggest an appropriate CG location to reduce instability.

Structured robust control-loop design with input saturations for tandem ducted fan vehicle

We propose the structured two-loop flight control system of a novel tandem ducted fan vehicle for near hover flight in consideration of actuator saturations on its dynamics. The prescribed controller architecture consists of static output feedback inner loop and four PI outer loop, which is a desirable and intuitive structure for practical implementation. The effect of a limited control activity on the control performance cannot be disregarded since it may lead to performance degradation or even instability. Moreover, at times, the input effort commanded by the control law is approaching the saturation levels in maneuvering flight or in the presence of wind gust disturbances. Therefore, a static anti-windup compensator is employed to preserve the closed-loop stability and performance. Both the feedback controller and the anti-windup compensator are computed simultaneously using recently available nonsmooth optimization techniques. Simulations using both a linearized model and a full nonlinear model of the vehicle under strong wind disturbances are presented to demonstrate its performance.

Modeling and simulation analysis of an unmanned tandem ducted fan vehicle with tilting system

Comprehensive study on control stability analysis before controller design is an indispensable important step for any flight system. In this paper, frequency modal responses and relative input-output controllability are analyzed quantitatively to provide valid instruction for structure improvement. In this project, tilting electric ducted fan (EDF) system is devised for an unmanned tandem ducted fan vehicle to improve the stability and controllability over wind disturbances. Forces and moments of the vehicle are investigated by comprehensive nonlinear modeling. Static thrust experiment has been done for more accurate parameters. Different reference speed of EDFs is considered and studied to evaluate the controllability of different channels.

Analysis of Characteristics for Mode Switch of Dual-Mode Electro-Mechanical Transmission (EMT)

Along with the development of hybrid electric vehicle, dual-mode electro-mechanical transmission (EMT) as an innovative power-split transmission technology, is widely applied in heavy-load vehicles. In this paper, a dynamic model for a dual-mode EMT based hybrid electric vehicle is developed which consists of two electrically variable transmission (EVT) modes and provides a platform for performance analysis of vehicle components including electro- mechanical characteristics analysis. Due to drive condition of the powertrain system, the electro- mechanical characteristics of mode switch is evaluated by a simulation model which is designed based on MATLAB/Simulink, and the simulation results are comparatively analyzed. It is expected that the research contents of this paper can be served effectively as a basis for future research in the field of EMT.

Research on Dynamic Coupled Characteristics of A Tracked Vehicle Gearbox

A tracked vehicle gearbox is divided into two subsystems-housing and gear train. Dynamic behaviors of the two subsystems are coupled practically. And the coupled characteristics describe the integrative dynamic behaviors of gearbox. This study proposes a coupled simulation model to investigate the interrelationship between dynamics of two subsystems. Multi-source excitations are numerically calculated to provide boundary conditions. The flexibility of transmission shafts and housing is mathematically described based on mode superposition. The coupled dynamic characteristics are analyzed with dynamics simulation computation. The flexibility of housing is one of the main causes to induce the fluctuation of dynamic responses of transmission shafts. The experimental results show that the proposed method is accurate through comparison of simulation results and test data.

Model predictive control-based controller design for a power-split hybrid electric vehicle

In order to meet the real-time optimal control requirements of a dual-mode power-split hybrid electric vehicle, a system predictive control strategy is studied in this paper. In order to deal with the contradiction between engine optimal fuel economy and the minimum range of battery SOC effectively, a control strategy used one dimensional search method for Multi-objective optimization control is proposed based on the analysis of structural characteristics of the power-split hybrid power system. This paper uses the improved fuel economy as the main target, the characteristic parameters of system in the future are predicted, and the speed and torque of the motor are adjusted with respect to the predictive results. An on-line optimization approach is applied to the real-time control, and the typical driving cycle is simulated by Matlab/Simulink. The simulation results show that the effects of the energy management strategy based on predictive control model are considerable, and this can realize the optimization of the engine operating point and improve the vehicles fuel economy.

Dynamic Characteristics of Vehicular Planetary Gears Influenced by Engine Excitation and Backlash Based on Nonlinear Torsional Vibration Model

Multiple gear ratios in automatic transmission are achievable with multi-stage planetary gears, where there are both the loaded planetary gear and the idle planetary gear under some gear ratios operation. Due to the change of road conditions, engine runs with different rotational speed and torque, which brings an external fluctuation excitation to the automatic transmission planetary gear set. In addition, the gear backlash becomes larger with the wear increasing during the running. Both engine excitation and gear backlash are important factors that not only influence the vibration characteristic and meshing state of the loaded planetary gear but also those of the idle planetary gear. The objective of this paper was to investigate the change of meshing force state of loaded planetary gear and idle planetary gear influenced by the different backlash and the engine excitation based on a nonlinear torsional vibration model.

Multi-Body Dynamics Simulation of A Tracked Vehicle Power Train in Consideration of Multi-Source Excitations

This study proposed a new efficient method to investigate tracked vehicle gear transmission system dynamics applying Finite element theory and multi-body dynamics. Torsional excitation was simulated based on an engine dynamic model by considering flexibility of crankshaft, maximum fire pressure and variable inertia. Gear mesh stiffness coefficient, mesh error excitation, bearing dynamic stiffness coefficient and damping coefficient were numerically calculated. The virtual prototype model of power train system including all aforementioned excitations was constructed. Dynamic responses of transmission shaft working with multi-source excitations were analyzed. The impact of each excitation source was discussed.