Dong-Wan Yoo

Dynamic modeling and control system design for Tri-Rotor UAV

In this paper, design, dynamics and control allocation of Tri-Rotor UAV are introduced. Tri-Rotor UAV has three rotor axes that are equidistant from its center of gravity. There are two designs of Tri-Rotor introduced in this paper. Single Tri-Rotor UAV has a servo-motor that has been installed on one of the three rotors, which enables a rapid control on its motion and its various attitude changes; unlike a Quad-Rotor UAV, which only depends on rpm of four rotors to control. The other design is called Coaxial Tri-Rotor UAV, which has two rotors installed on each rotor axis. Since Tri-Rotor type UAV has the yawing problem induced from an unpaired rotors reaction torque, it is required to derive accurate dynamics and design control logics for both Single and Coaxial Tri-Rotors. For that reason, control strategy for each Tri-Rotor type is proposed and nonlinear simulations of altitude, Euler angles, and angular velocity responses have been done by using classical PID controller. Simulation results show that the proposed control strategies are appropriate for the control of Single and Coaxial Tri-Rotor UAV.

Dynamic Modeling and Stabilization Techniques for Tri-Rotor Unmanned Aerial Vehicles

The design, dynamics, and control allocation of tri-rotor unmanned aerial vehicles (UAVs) are introduced in this paper. A trirotor UAV has three rotor axes that are equidistant from its center of gravity. Two designs of tri-rotor UAV are introduced in this paper. The single tri-rotor UAV has a servo-motor that is installed on one of the three rotors, which enables rapid control of its motion and its various attitude changes–unlike a quad-rotor UAV that depends only on the angular velocities of four rotors for control. The other design is called ‘coaxial tri-rotor UAV,’ which has two rotors installed on each rotor axis. Since the tri-rotor type of UAV has the yawing problem induced from an unpaired rotor’s reaction torque, it is necessary to derive accurate dynamic and design control logic for both single and coaxial tri-rotors. For that reason, a control strategy is proposed for each type of trirotor, and nonlinear simulations of the altitude, Euler angle, and angular velocity responses are conducted by using a classical proportional-integral-derivative controller. Simulation results show that the proposed control strategies are appropriate for the control of single and coaxial tri-rotor UAVs.

Optical Flow Based Collision Avoidance of Multi-Rotor UAVs in Urban Environments

This paper is focused on dynamic modeling and control system design as well as vision based collision avoidance for multi-rotor unmanned aerial vehicles (UAVs). Multi-rotor UAVs are defined as rotary-winged UAVs with multiple rotors. These multi-rotor UAVs can be utilized in various military situations such as surveillance and reconnaissance. They can also be used for obtaining visual information from steep terrains or disaster sites. In this paper, a quad-rotor model is introduced as well as its control system, which is designed based on a proportional-integral-derivative controller and vision-based collision avoidance control system. Additionally, in order for a UAV to navigate safely in areas such as buildings and offices with a number of obstacles, there must be a collision avoidance algorithm installed in the UAV’s hardware, which should include the detection of obstacles, avoidance maneuvering, etc. In this paper, the optical flow method, one of the vision-based collision avoidance techniques, is introduced, and multi-rotor UAV’s collision avoidance simulations are described in various virtual environments in order to demonstrate its avoidance performance.

Differential Game Based Air Combat Maneuver Generation Using Scoring Function Matrix

A differential game theory based approach is used to develop an automated maneuver generation algorithm for Within Visual Range (WVR) air-to-air combat of unmanned combat aerial vehicles (UCAVs). The algorithm follows hierarchical decisionmaking structure and performs scoring function matrix calculation based on differential game theory to find the optimal maneuvers against dynamic and challenging combat situation. The score, implying how much air superiority the UCAV has, is computed from the predicted relative geometry, relative distance and velocity of two aircrafts. Security strategy is applied at the decision-making step. Additionally, a barrier function is implemented to keep the airplanes above the altitude lower bound. To shorten the simulation time to make the algorithm more real-time, a moving horizon method is implemented. An F-16 pseudo 6-DOF model is used for realistic simulation. The combat maneuver generation algorithm is verified through three dimensional simulations.

Study on payload stabilization method with the slung-load transportation system using a quad-rotor

This paper introduces the payload stabilization method for safe payload transportation. We assumed that the vehicle and the payload are connected by wires, which is called the slung-load system. For the slung-load system, the wire generates various constraint forces between the vehicle and the payload. Various types of slung-load systems can be defined by various numbers of vehicles and payloads, but in this research, we used the slung-load system that is composed of only one vehicle and one payload. To model the slung-load system, we applied the Udwadia-Kalaba equation (UKE) to account for the slung-load system with various constraint forces. To transport the payload safely to destination point from the starting point, we suggest the payload stabilization method that modifies the structure of position controller of a quad-rotor. Controller gain design processes are also performed. Lastly, using the derived system model based on the UKE, simulation and flight tests are performed to demonstrate the performance of the payload stabilization method we suggested. Additionally, a particular unmanned aerial vehicle of quad-rotor is chosen as the main platforms of the entire system due to its advantages such as simple control logic implementation and maintainability.

ATTITUDE CONTROL SYSTEM DESIGN FOR AGGRESSIVE MANEUVER OF A QUAD-ROTOR UAV

This paper addresses the methodologies of attitude control system design and aggressive maneuver for a Quad-rotor UAV. For this purpose, first of all, Quad-rotor UAV’s dynamic model is derived, and it was used for designing an attitude controller of the Quad-rotor UAV. Attitude controllers are designed by two different methods. One is open-loop control system design and the other one is closed-loop control system design. Performances of both controllers are tested by 6-DOF simulation assuming that using the motion capture system on indoor flight test. Closed-loop control system is designed by conventional PID control method. In case of the open-loop control system, control inputs are calculated by quad-rotor dynamic model and thrust system model that are identified by thrust test. 6-DOF simulation environment was constructed in order to verify the performances of attitude controllers. We assume that flight tests are performed with motion capture system in an indoor facility. Therefore, 6-DOF simulation environment considers the indoor motion capture system. In addition, we present a methodology for an aggressive maneuver; especially flip maneuver method that is applied from the designed controllers in previous researches.

Conceptual Design of a Multi-Rotor Unmanned Aerial Vehicle based on an Axiomatic Design

This paper presents the conceptual design of a multi-rotor unmanned aerial vehicle (UAV) based on an axiomatic design. In most aerial vehicle design approaches, design configurations are affected by past and current design tendencies as well as an engineer’s preferences. In order to design a systematic design framework and provide fruitful design configurations for a new type of rotorcraft, the axiomatic design theory is applied to the conceptual design process. Axiomatic design is a design methodology of a system that uses two design axioms by applying matrix methods to systematically analyze the transformation of customer needs into functional requirements (FRs), design parameters (DPs), and process variables. This paper deals with two conceptual rotary wing UAV designs, and the evaluations of tri-rotor and quad-rotor UAVs with proposed axiomatic approach. In this design methodology, design configurations are mainly affected by the selection of FRs, constraints, and DPs.

MODELING OF THE COOPERATIVE SLUNG-LOAD TRANSPORTATION SYSTEM WITH MULTIPLE QUAD-ROTOR UNMANNED AERIAL VEHICLES

This research concerns the modeling of the cooperative transportation system using multiple quad-rotor UAVs. Due to the advantages of the quad-rotor UAVs, such as the capability of hovering and the simpler control logic implementation, they are selected as the main platforms for the transportation system. This paper first describes the modeling and control strategies of the quad-rotor UAVs in order to give a brief explanation of the main platform. Among the existing methodologies on the UAV cooperative transportation, the technique used in this research to model the system is the slung-load system using Udwadia-Kalaba equation (UKE). UKE is applied in order to deal with various constraint forces existing in the system, since the slung-load system is equipped with a number of inelastic cables to carry a payload. Since the modeling of movements of the cable is also important when the constrained forces are not present, the logic of tightening and slackening of the wires is also included in the system model. Stability analysis and controller design of such model are also performed. Finally, with the finally derived system model based on UKE, a number of numerical simulations are carried out in order to verify the slung-load transportation system model.

Distributed Task Assignment Algorithm for SEAD Mission of Heterogeneous UAVs Based on CBBA Algorithm

This paper presents a distributed task assignment algorithm for the suppression of enemy air defense (SEAD) mission of heterogeneous UAVs, based on the consensus-based bundle algorithm (CBBA). SEAD mission can be modeled as a task assignment problem of multiple UAVs performing multiple air defense targets, and UAVs performing SEAD mission consist of the weasel for destruction of enemy`s air defense system and the striker for the battle damage assessment (BDA) or other tasks. In this paper, a distributed task assignment algorithm considering path-planning in presence of terrain obstacle is developed for heterogeneous UAVs, and then it is applied to SEAD mission. Through numerical simulations the performance and the applicability of the proposed method are tested.