scholarly journals ACT/FHS System Identification Including Rotor and Engine Dynamics

2019 ◽  
Vol 64 (2) ◽  
pp. 1-12
Author(s):  
Susanne Seher-Weiß
Keyword(s):  
Control System ◽  
System Identification ◽  
Flight Control ◽  
The Body ◽  
Likelihood Method ◽  
Flight Control System ◽  
Transmission Zeros ◽  
Model Following ◽  
Systems Models ◽  
German Aerospace

At the German Aerospace Center (DLR) Institute of Flight Systems, models of the Active Control Technology/Flying Helicopter Simulator (ACT/FHS), an EC135 with a fly-by-wire/light flight control system, are needed for control law development and simulation. Thus, models are sought that cover the whole flight envelope and are valid over a broad range of frequencies. Furthermore, if the models are to be used in the feedforward loop of the model following the control system, they have to be invertible and thus should not have any positive transmission zeros. For rotor flapping, the explicit formulation with flapping angles was modified slightly to avoid positive transmission zeros. For the regressive lead–lag, a simple model formulation was found that needs only one dipole with two states. The engine dynamics were first modeled separately and then coupled to the body/rotor model. The final integrated model has 17 states and yields a good match for frequencies up to 30 rad/s. All system identification was performed using the maximum likelihood method in the frequency domain.

System identification and robust attitude control of an unmanned helicopter using novel low-cost flight control system

2019 ◽  
Vol 234 (5) ◽  
pp. 634-645
Author(s):  
Mohammad Hossein Khalesi ◽  
Hassan Salarieh ◽  
Mahmoud Saadat Foumani
Keyword(s):  
Control System ◽  
Robust Control ◽  
System Identification ◽  
Flight Control ◽  
Low Cost ◽  
Superior Performance ◽  
Raspberry Pi ◽  
Unmanned Helicopter ◽  
Flight Control System ◽  
Robust Control System

In recent years, unmanned aerial systems have attracted great attention due to the electronic systems technology advancements. Among these vehicles, unmanned helicopters are more important because of their special abilities and superior performance. The complex nonlinear dynamic system (caused by main rotor flapping dynamics coupled with the rigid body rotational motion) and considerable effects of ambient disturbance make their utilization hard in actual missions. Attitude dynamics have the main role in helicopter stabilization, so implementing proper control system for attitude is an important issue for unmanned helicopter hovering and trajectory tracking performance. Besides this, experimental utilization of low-cost flight control system for unmanned helicopters is still a challenging task. In this article, dynamic modeling, system identification, and robust control system implementation of roll and pitch dynamics of an unmanned helicopter is performed. A TRex-600E radio-controlled helicopter is equipped with a novel low-cost flight control system designed and constructed based on Raspberry Pi Linux-based microcomputer. Using Raspberry Pi makes this platform simpler to utilize and more time and cost-effective than similar platforms used before. The experiments are performed on a 5-degree-of-freedom testbed. The robust control system is designed based on [Formula: see text] method and is evaluated in real flight tests. The experiment results show that the proposed platform has the ability to successfully control the roll and pitch dynamics of the unmanned helicopter.

scholarly journals Real-Time Visual Feedback Control of Multi-Camera UAV

2021 ◽  
Vol 33 (2) ◽  
pp. 263-273
Author(s):  
Dongqing He ◽  
◽  
Hsiu-Min Chuang ◽  
Jinyu Chen ◽  
Jinwei Li ◽  
...  
Keyword(s):  
Control System ◽  
Obstacle Avoidance ◽  
Global Positioning System ◽  
Flight Control ◽  
Visual Servoing ◽  
Visual Recognition ◽  
The Body ◽  
Flight Control System ◽  
Global Positioning ◽  
Visual Feedback Control

Recently, flight control of unmanned aerial vehicles (UAVs) in non-global positioning system (GPS) environments has become increasingly important. In such an environment, visual sensors are important, and their main roles are self-localization and obstacle avoidance. In this paper, the concept of a multi-camera UAV system with multiple cameras attached to the body is proposed to realize high-precision omnidirectional visual recognition, self-localization, and obstacle avoidance simultaneously, and a two-camera UAV is developed as a prototype. The proposed flight control system can switch between visual servoing (VS) for collision avoidance and visual odometry (VO) for self-localization. The feasibility of the proposed control system was verified by conducting flight experiments with the insertion of obstacles.

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