Miaobo Dong

Modeling and Control of the Yaw Channel of a UAV Helicopter

We present in this paper the modeling and flight-control-system design for the yaw channel of an unmanned-aerial-vehicle (UAV) helicopter using a newly developed composite nonlinear feedback (CNF)-control technique. The CNF-control method has been proven to be capable of yielding a fast transient response with no or very minimal overshoot in tracking a specific target. From the actual flight tests on our UAV helicopter, it has been found that the commonly used yaw dynamical model for the UAV helicopter proposed in the literature is very rough and inaccurate, which might cause the helicopter to shake severely in certain flight conditions. This motivates us to first obtain a more accurate model for the yaw channel of our UAV helicopter. The CNF-control method is then utilized to design an efficient control law, which gives excellent overall performance. In particular, our design has achieved a Level 1 performance according to the standards set for military rotorcraft. The results are verified through actual flight tests.

Brief paper: Design and implementation of an autonomous flight control law for a UAV helicopter

In this paper, we present the design and implementation of an autonomous flight control law for a small-scale unmanned aerial vehicle (UAV) helicopter. The approach is decentralized in nature by incorporating a newly developed nonlinear control technique, namely the composite nonlinear feedback control, together with dynamic inversion. The overall control law consists of three hierarchical layers, namely, the kernel control, command generator and flight scheduling, and is implemented and verified in flight tests on the actual UAV helicopter. The flight test results demonstrate that the UAV helicopter is capable of carrying out complicated flight missions autonomously.

Modeling and Control System Design for a UAV Helicopter

We present in this paper a linearized hovering model of a UAV helicopter obtained using the in-flight data generated through a perturbation method. The UAV helicopter is constructed from a radio-controlled helicopter by integrating an onboard system, which includes a data processing unit, a data acquisition system, a wireless communications and all necessary sensors. A flight control law is then designed using a newly developed nonlinear control technique, i.e. the composite nonlinear feedback control. Actual flight testing shows that the design is successful

Development of a Real-time Onboard and Ground Station Software System for a UAV Helicopter

We report in this paper the development of a real-time software system for an unmanned aerial vehicle (UAV) helicopter, which consists of an embedded computer onboard and a ground station served by a laptop. The software system for the onboard computer performs multiple tasks including data acquisition and measurement, servo driving, automatic flight control implementation, communications and data logging. The system for the ground station gives a flexible graphical interface monitoring the real-time status of the UAV helicopter. We present the frameworks and structures of the onboard and ground station systems. The onboard system employs a framework of multiple task threads with each thread being assigned to perform a specific task. Management and time scheduling for task threads together with the detailed implementation of automatic flight control laws are the main focuses of the onboard software system. A behavior-based architecture is designed to address task scheduling and event disposal for automatic control. A hierarchical and componential structure is developed to integrate multiple control laws and perform various helicopter behaviors. The ground station software system employs a two-layer framework, i.e., data transferring in background and data visualization in foreground.A variety of views are developed to display in-flight data received from the UAV helicopter in different forms including a 3D monitoring panel, which displays real-time data in 3D on the ground station.

Development of an Unmanned Coaxial Rotorcraft for the DARPA UAVForge Challenge

In this paper, we present a comprehensive design for a fully functional unmanned rotorcraft system: GremLion. GremLion is a new smallscale unmanned aerial vehicle (UAV) concept using two contra-rotating rotors and one cyclic swash-plate. It can fit within a rucksack and be easily carried by a single person. GremLion is developed with all necessary avionics and a ground control station. It has been employed to participate in the 2012 UAVForge competition. The proposed design of GremLion consists of hardware construction, software development, dynamics modeling and flight control design, as well as mission algorithm investigation. A novel computer-aided technique is presented to optimize the hardware construction of GremLion to realize robust and efficient flight behavior. Based on the above hardware platform, a real-time flight control software and a ground control station (GCS) software have been developed to achieve the onboard processing capability and the ground monitoring capability respectively. A GremLion mathematical model has been derived for hover and near hover flight conditions and identified from experimental data collected in flight tests. We have combined H1 technique, a robust and perfect tracking (RPT) approach, and custom-defined flight scheduling to design a comprehensive nonlinear flight control law for GremLion and successfully realized the automatic control which includes take-off, hovering, and a variety of essential flight motions. In addition, advanced mission algorithms have been presented in the paper, including obstacle detection and avoidance, as well as target following. Both ground and flight experiments of the complete system have been conducted including autonomous hovering, waypoint flight, etc. The test results have been presented in this paper to verify the proposed design methodology.

Design and implementation of a hardware-in-the-loop simulation system for small-scale UAV helicopters

We present in the paper the design of a hardware-in-the-loop simulation framework and its actual implementation on our custom constructed unmanned-aerial-vehicle (UAV) helicopter systems. Real-time hardware-in-the-loop simulation is one of the most effective methods for the verification of the overall control performance and safety of the UAVs before conducting actual flight tests. In our proposed framework, four modules, which include onboard hardware, flight control, ground station and software, are integrated together to realize the hardware-in-the-loop simulation. This design is successfully utilized for simulating several flight tests including basic flight motions, full-envelope flight and multiple UAV formation flight. Results obtained show that the constructed hardware-in-the-loop simulation system is highly effective and useful.

Comprehensive Modeling and Control of the Yaw Dynamics of a UAV Helicopter

The modeling of yaw dynamics of a UAV helicopter is focused on together with its control system design. From the flight tests on our actual UAV helicopter, it has been found that the yaw dynamical model for the UAV helicopter proposed in the literatures is very rough and inaccurate, which might cause the helicopter to shake severely in certain flight conditions. A complete examination is carried out to identify a perfect model of the yaw channel in the UAV helicopter. It would be found that the assumption in the old model is not appropriate. Some advanced control schemes will then be adopted to solve the shaking problem observed in the yaw channel.

Design and implementation of a nonlinear flight control law for the yaw channel of a UAV helicopter

We present in this paper a flight control system design for the yaw channel of a UAV helicopter using a newly developed composite nonlinear feedback (CNF) control technique. From the actual flight tests on our UAV helicopter, it has been found that the commonly used yaw dynamical model for the UAV helicopter proposed in the literatures is very rough and inaccurate. This motivates us to first obtain a comprehensive model for the yaw channel of our UAV helicopter. The CNF control method is then utilized to design an efficient control law, which gives excellent overall performance. In particular, our design has achieved a level 1 performance according to the standards set for military rotorcraft. The results are verified through actual flight tests.

A comprehensive software system architecture for unmanned aerial vehicles

We present in this paper a comprehensive software system architecture for unmanned aerial vehicles. More specifically, a top-down divide and conquer method is utilized in developing the logical representation of the overall system, with standard professional approaches, such as data flow diagram and task structure diagram. The overall system consisting of two unmanned vehicles and a ground control system is demonstrated with both hardware-in-the-loop simulation and practical formation flight tests. We should note that the same architecture can be adopted in other forms of unmanned systems including unmanned ground vehicles and underwater vehicles.

Development of an Unconventional Unmanned Coaxial Rotorcraft: GremLion

In this paper, we present an unmanned system design methodology for a fully functional unmanned rotorcraft system: GremLion, developed with all necessary avionics and a ground control station. It has been employed to participate in the 2012 UAVForge competition. The proposed design methodology consists of hardware construction, software development, dynamic modeling and flight control, as well as mission algorithms. The test results have been presented in this paper to verify the proposed design methodology.