Qingbo Geng

Vision based ground target tracking for rotor UAV

This paper studies an efficient ground target tracking algorithm for rotor Unmanned Aerial Vehicle (UAV) to overcome the contradiction among the target tracking rapidity, precision and robustness for aerial vehicle. Firstly, Scale Invariant Feature Transform (SIFT) algorithm, which has a better robust performance during rotation, scaling and changes of illumination, is utilized to extract and match the feature points in order to realize target recognition and positioning. Secondly, using top-down tracking method, Kalman filter is combined to estimate the target position in the next frame and search target in the predicted area, it can avoid blind matching, improve tracking rapidity and reduce the ratio of losing target. Finally, an experimental platform of rotor UAV visual tracking is set up and the ground target tracking algorithm is tested. The experiment results show that the algorithm can achieve ground target tracking effectively and has good real-time performance and robustness.

Modeling and control for longitudinal attitude of a twin-rotor tail-sitter unmanned aerial vehicle

In this paper, the modeling and model reference adaptive control (MRAC) for longitudinal attitude of a twin-rotor tail-sitter unmanned aerial vehicle (UAV), which is highly unstable during flight, are presented. First, the attitude dynamic models are established. Linearized model for longitudinal attitude in vertical flight mode is given that is used in later derivation of controller as well as for testing the algorithms in simulation. Then, a control law based on the MRAC technique is utilized to stabilize the longitudinal attitude control system with uncertainty. Simulation results show that the MRAC of pitch angle has good trajectory tracking and the designed control law has strong adaptive ability and anti-jamming ability.

Design of control system for an unmanned semi-submersible vehicle

Given the fact that ocean is vast and its condition is always changing, it is difficult to collect meteorological and oceanographic data. In this paper, a semi-submersible un-manned surface vehicle is introduced to decrease the difficulties. The hardware and software design of the USV, which is a rigid hull with tow screw propellers, is discussed at the beginning. Then, the mathematics model and control algorithm related to path following control of the USV are presented. Finally, several experiments are conducted to verify the feasibility and control performance of the unmanned vehicle.

An active disturbance rejection controller design and parameter tuning for helicopter with slung-load

The ability of a helicopter to carry externally slung loads makes it very versatile for many civil and military operations. For Helicopter slung-load system in the presence of strong disturbances and complex effects from its load, an Active Disturbance Rejection Control method(ADRC) will be applied to helicopter slung-load system and its parameter tuning based on genetic algorithm(GA) will be proposed in this paper. An extended state observer(ESO) of ADRC can estimate the impact from parametric uncertainties and disturbances from externally load, realize online compensations and other uncertainties in the helicopter dynamics can be rejected by active disturbance rejection control to achieve small tracking error. Finally, simulation results show that the proposed ADRC Control method obtains desirable transient performance and robustness for dynamics of helicopter with slung-load.

Design of σ-mod CMRAC algorithm for fixed-wing UAV9

In this paper, we present a new model reference adaptive control (MRAC) for flight control system of unmanned aerial vehicle (UAV) with uncertainties. The beginning of new algorithm design is combining direct MRAC with indirect adaptive control, which is called composite model reference adaptive control (CMRAC). In the indirect part, we use a reverse filter to filter the system input. Then, we employ σ-modification to improve robustness of the flight control system. CMRAC with this kind of modification results in better tracking performance in the presence of parameter uncertainties and rapidly changing command input. Stability of the closed-loop system is formally proven by using Lyapunov theory. The effectiveness of the proposed algorithm is also illustrated through some simulations about the longitudinal dynamics of UAV.

New composite MRAC with modification for fixed-wing UAV

In this paper, we present a new model reference adaptive control (MRAC) for flight control of fixed-wing unmanned aerial vehicle (UAV) with uncertainties and disturbance. The beginning of new algorithm design is combining direct MRAC with indirect adaptive control, which is called composite MRAC (CMRAC). In the aspect of direct MRAC, we substitute a Luenberger-like reference model for a typical one, namely adding an error feedback term. In the indirect part, we use a reverse filter to filter the system input. This kind of combination results in smooth transient performance and extremely small tracking error. In addition, we design adaptive laws with σ-modification to improve robustness in the presence of disturbances. Stability of the closed-loop system is formally proven by using Lyapunov theory. The effectiveness of the proposed algorithm is also illustrated through some simulations about the longitudinal dynamics of UAV.

Switching Control System Based on Robust Model Reference Adaptive Control

For conventional adaptive control, time-varying parametric uncertainty and unmodeled dynamics are ticklish problems, which will lead to undesirable performance or even instability and nonrobust behavior, respectively. In this study, a class of discrete-time switched systems with unmodeled dynamics is taken into consideration. Moreover, nonlinear systems are here supposed to be approximated with the class of switched systems considered in this paper, and thereby switching control design is investigated for both switched systems and nonlinear systems to assure stability and performance. For robustness against unmodeled dynamics and uncertainty, robust model reference adaptive control (RMRAC) law is developed as the basis of controller design for each individual subsystem in the switched systems or nonlinear systems. Meanwhile, two different switching laws are presented for switched systems and nonlinear systems, respectively. Thereby, the authors incorporate the corresponding switching law into the RMRAC law to construct two schemes of switching control respectively for the two kinds of controlled systems. Both closed-loop analyses and simulation examples are provided to illustrate the validity of the two proposed switching control schemes. Furthermore, as to the proposed scheme for nonlinear systems, its potential for practical application is demonstrated through simulations of longitudinal control for F-16 aircraft.

High performance L 1 adaptive control design for longitudinal dynamics of fixed-wing UAV

For longitudinal dynamics of Fixed-wing Unmanned Aerial Vehicle (UAV) with strong disturbance and parameter uncertainty, a new High Performance L1 Adaptive Control (HPL1AC) method is proposed in this paper. HPL1AC is based on combination of Ackermann Pole Assignment Controller (APAC) and L1 adaptive controller, where APAC is utilized to stabilize the closed-loop system and L1 adaptive controller is adopted to guarantee control performance in the presence of parameter uncertainty. It is worth mentioning that BGF (Bounded-Gain Forgetting) estimator is introduced to realize time-varying adaption for adaptive gain matrix. Finally, simulation results show that the proposed HPL1AC algorithm obtains desirable transient performance and robustness for shot period dynamics of F-16 UAV.

Composite μ-mod model reference adaptive control with input constraints

Based on the widely used model reference adaptive control (MRAC), a new controller is proposed to tackle a class of single-input(SI) systems in the presence of matched uncertainties and input constraints. The core idea is to substitute conventional simple direct adaptive control for composite model adaptive control (CMRAC). The main control structure that results in tractable responsibility is discussed in tail, in which the performance is adaptive to address the constraints of input in addition to retaining the usual transient properties and dynamic stability. To this end, a typical positive μ-mod method is developed on the basis of CMRAC frame to aim at a correct control. The formulated method supplies a convenient and intuitive interpretation to solve the control design problem, meanwhile utilizing the basic MRAC ideas. Moreover, Simulation is conducted to evaluate the control performance of longitudinal dynamics of an aerial vehicle.

On control design for a class of parametric uncertain nonlinear systems

In this paper, a class of nonlinear systems with parametric uncertainties in the control inputs are taken into consideration and several control design approaches are investigated and compared by simulation studies. As for nonlinearity, one popular method is gain-scheduling, of which the main idea is to linearize the system at many operation points and then adopt linear control design. However, it could not achieve good performance in the presence of uncertainties. Augmenting the gain-scheduling controller with adaptive control law may improve the closed-loop dynamics, but another disadvantage is the large quantities of data processing in advance resulting from linearization which would be impossibly addressed once we take the gain-scheduling as control strategy. Therefore, nonlinear control technique of less dependence on the mathematical model is our best choice. ADRC (active disturbance rejection control) benefits from its ESO (extended state observer) to cope with the disturbance and uncertainties. Moreover, the nonlinear feedback control based on ESO upgrades the performance of the closed-loop system. Simulations are conducted to validate the effectiveness of ADRC, and comparison is carried out to figure out advantages and disadvantages for each control law.