DongBin Lee

Output Feedback Tracking Control of an Underactuated Quad-Rotor UAV

This paper proposes a new controller for an underactuated quad-rotor family of small-scale unmanned aerial vehicles (UAVs) using output feedback (OFB). Specifically, an observer is designed to estimate the velocities and an output feedback controller is designed for a nonlinear UAV system in which only position and angles are measurable. The design is performed via a Lyapunov type analysis. A semi- global uniformly ultimate bounded (SGUUB) tracking result is achieved. Simulation results are shown to demonstrate the proposed approach.

Robust tracking control of an underactuated quadrotor aerial-robot based on a parametric uncertain model

In this paper, the tracking control of a underactuated quadrotor aerial vehicle is presented where position and yaw trajectory tracking is achieved using feedback control system. The control design is complicated by considering parametric uncertainty in the dynamic modeling of the quadrotor aerial-robot. Robust control schemes are then designed using a Lyapunov-based approach to compensate for the unknown parameters in each dynamic subsystem model. Lyapunov-type stability analysis suggests a global uniform ultimately bounded (GUUB) tracking result.

Velocity control for a quad-rotor uav fly-by-camera interface

A quad-rotor unmanned aerial vehicle (UAV) and a two-degree-of-freedom (DOF) camera unit are combined to achieve a fully-actuated fly-by-camera positioning system. The flight control interface allows the user to command motions in the camera frame of reference - a natural perspective for surveillance and inspection tasks. A nonlinear velocity controller, derived using Lyapunov stability arguments, produces simultaneous complementary motion of the quad-rotor vehicle and the camera positioning unit. The controller achieves globally uniform ultimate boundedness (GUUB) on all velocity error terms.

Robust output tracking control of a surface vessel

In this paper, tracking control of a three degree- of-freedom marine vessel is examined. The primary motivation for this work is the compensation needed for the added mass common to surface vessels, resulting in an asymmetric inertia matrix. Two control schemes are considered: a full- state feedback controller and an output feedback controller. Numerical simulation results are shown to demonstrate the validity of these proposed controllers.

Control of a remotely operated quadrotor aerial vehicle and camera unit using a fly-the-camera perspective

This paper presents a mission-centric approach to controlling the optical axis of a video camera mounted on a camera manipulator and fixed to a quadrotor remotely operated vehicle. A four-DOF quadrotor, UAV model will be combined with a two-DOF camera kinematic model to create a single system to provide a full six DOF actuation of the camera view. This work proposed exploits that all signals are described in camera frame. The closed-loop controller is designed based on a Lyapunov-type analysis so that the tracking result is shown to produce globally uniformly ultimately bounded (GUUB). Computer simulation results are provided to demonstrate the suggested controller.

Perceptually salient haptic rendering for enhancing kinesthetic perception in virtual environments

Kinesthetic or dynamic touch involves the use of muscle sensitivity to perceive mechanical properties of objects that are gripped in the hand and wielded in space. Many previous studies with real objects have investigated the mechanical properties that underlie human haptic perception. Few virtual environments, however, have systematically incorporated the relevant mechanical parameters underlying kinesthetic perception. In this study, the ability of a haptic device to render kinesthetic information regarding the inertial properties of virtual objects was tested. Results suggest that users were able to perceive length of rendered virtual objects via the haptic device. Further, users can be trained using the haptic device to increase sensitivity to specific mechanical parameters (like inertia) that are perceptually salient in perceiving properties of rendered objects. The primary implication of this finding is that rendering kinesthetic parameters and employing feedback in a systematic manner may increase the realism of virtual environments and also improve haptic perception.

Adaptive output tracking control of a surface vessel

In this paper, the tracking control of a three degree-of-freedom marine vessel is examined. The novelty of this work is the transformation of the asymmetric inertia matrix into a symmetric, positive definite matrix. The asymmetry arises from the added mass common to practical surface vessels and creates a significant challenge for control design. The control design is further complicated by the parametric uncertainties in the dynamic model of the vessel. Two adaptive control schemes with a projection-based adaptation law are proposed: a full-state feedback controller and an output feedback controller. Both controllers are known to yield a uniformly ultimately bounded tracking result in the presence of parametric uncertainty. Numerical simulation results are shown to demonstrate the validity of the proposed controllers.

A Five DOF haptic rendering algorithm using multiple contact points

With the proliferation of haptic devices, there has been significant research toward realistic haptic rendering of virtual environments. Currently, the majority of haptic devices provide only three degrees-of freedom (3 DOF), but 5 and 6 DOF devices are becoming more common. This paper presents a method of using existing 3 DOF rendering techniques to produce forces for a 5 or 6 DOF device when true 6 DOF rendering is unavailable. Point-force 3 DOF rendering that is most commonly used in commercial haptic applications is simple and fast for basic haptic rendering; however, this creates unrealistic haptic effects when an avatar other than a point is considered. As a solution, a 6 DOF force and torque algorithm is presented based on multiple contact points. Using the multi-point torque rendering approach, forces are rendered in three linear dimensions using existing 3 DOF algorithms, and up to three additional torque degrees-of freedom are calculated based on the forces on multiple points. This capability enhances haptic realism without modifying the legacy rendering. Finally, this algorithm is demonstrated using a 5 DOF haptic interface. The results from test observations suggest that the 5 DOF rendering algorithm functions as expected.

Fly-the-Camera Perspective: Control of a Remotely Operated Quadrotor UAV and Camera Unit

This Chapter presents a mission-centric approach to controlling the optical axis of a video camera mounted on a camera positioner and fixed to a quadrotor remotely operated vehicle. The approach considers that for video collection tasks a single operator should be able to operate the system by ”flying-the-camera”; that is, collect video data from the perspective that the operator is looking out of and is the pilot of the camera. This will allow the control of the quadrotor and the camera manipulator to be fused into single robot manipulator control problem where the camera is positioned using the four degree-of-freedom (DOF) quadrotor and the two DOF camera positioner to provide a full six DOF actuation of the camera view. Design of a closed-loop controller to implement this approach is demonstrated using a Lyapunov-type analysis. Computer simulation results are provided to demonstrate the suggested controller. Historically, the primary driver for UAV reconnaissance capabilities has been military applications; however, we appear to be at the juncture where the cost and capabilities of such systems has become attractive in civilian applications. The success of recent UAV systems has raised expectations for an increased rate of technology development in critical factors such as low-cost, reliable sensors, air-frame construction, more robust and lightweight material, higher energy-density battery technologies, and interfaces that require less operator training. One of the essential technologies is the camera positioner, which includes camera, camera base, and multi-axis servo platform. The potential for UAVs with camera positioners has been well established in many applications as diverse as fire fighting, emergency response, military and civilian surveillance, crop monitoring, and geographical registration. Many research and commercial groups have provided convincing demonstrations of the utility of UAVs in these applications. Most of the commercial systems are equipped with camera positioners as standard equipment; however, the use of the camera is not integrated with the control of the UAV. The typical structures of a camera positioner include pan-tilt, tilt-roll, or pan/tilt/roll revolute joints or multi-axis gimbals. When considering the actuator of the camera gimbal, rate-gyros or encoders are used to measure the orientations. If the system is small and lightweight, the actuator dynamics can be discounted or neglected in the control of the UAV. Heavier systems, relative to the UAV, may require that the interaction of the camera