An organic light emitting display apparatus that has high (or improved) contrast and/or impact resistance. The organic light emitting display apparatus includes: a substrate; an organic light emitting device on the substrate to display an image; a sealing member on the organic light emitting device; a semitransparent film on a surface of the sealing member facing away from the organic light emitting device to transmit a portion of external light and to reflect another portion of the external light; a passivation film on the semitransparent film to protect the semitransparent film; and a transmissive black layer between the sealing member and the organic light emitting device to increase contrast, wherein the semitransparent film has a refractive index greater than that of the passivation film.

Organic light emitting display apparatus

We present a novel, deeply embedded robotics middleware and programming environment. It uses a multithreaded, publish-subscribe design pattern and provides a Unix-like software interface for micro controller applications. We improve over the state of the art in deeply embedded open source systems by providing a modular and standards-oriented platform. Our system architecture is centered around a publish-subscribe object request broker on top of a POSIX application programming interface. This allows to reuse common Unix knowledge and experience, including a bash-like shell. We demonstrate with a vertical takeoff and landing (VTOL) use case that the system modularity is well suited for novel and experimental vehicle platforms. We also show how the system architecture allows a direct interface to ROS and to run individual processes either as native ROS nodes on Linux or nodes on the micro controller, maximizing interoperability. Our microcontroller-based execution environment has substantially lower latency and better hardware connectivity than a typical Robotics Linux system and is therefore well suited for fast, high rate control tasks.

/pdf/px4-a-node-based-multithreaded-open-source-robotics-50m35kksn5.pdf

PX4: A node-based multithreaded open source robotics framework for deeply embedded platforms

This study gives the mathematic model of a quadrotor unmanned aerial vehicle (UAV) and then proposes a robust nonlinear controller which combines the sliding-mode control technique and the backstepping control technique. To achieve Cartesian position trajectory tracking capability, the construction of the controller can be divided into two stages: a regular SMC controller for attitude subsystem (inner loop) is first developed to guarantee fast convergence rapidity of Euler angles and the backstepping technique is applied to the position loop until desired attitudes are obtained and then the ultimate control laws. The stability of the closed-loop system is guaranteed by stabilizing each of the subsystems step by step and the robustness of the controller against model uncertainty and external disturbances is investigated. In addition, an adaptive observer-based fault estimation scheme is also considered for taking off mode. Simulations are conducted to demonstrate the effectiveness of the designed robust nonlinear controller and the fault estimation scheme.

Robust Backstepping Sliding-Mode Control and Observer-Based Fault Estimation for a Quadrotor UAV

We describe a prototype 75 g micro quadrotor with onboard attitude estimation and control that operates autonomously with an external localization system The motivation for designing quadrotors at this scale comes from two observations First, the agility of the robot increases with a reduction in size, a fact that is supported by experimental results in this paper Second, smaller robots are able to operate in tight formations in constrained, indoor environments We describe the hardware and software used to operate the vehicle as well our dynamic model We also discuss the aerodynamics of vertical flight and the contribution of ground effect to the vehicle performance Finally, we discuss architecture and algorithms to coordinate a team of these quadrotors, and provide experimental results for a team of 20 micro quadrotors

/pdf/towards-a-swarm-of-agile-micro-quadrotors-2fehv2bsdt.pdf

Towards a swarm of agile micro quadrotors

A liquid crystal display device and a method of manufacturing the same. The liquid crystal display device includes a plurality of pixel cells on a substrate and a common voltage line. The common voltage line provides a common voltage to the pixel cells, and includes first to third s interconnection patterns which are sequentially stacked over the substrate. Each of the pixel cells includes a storage capacitor which includes a lower electrode, and an upper electrode over the lower electrode. The second interconnection pattern includes the same material as a material of the upper electrode, and is formed in the same process as a process of the upper electrode.

Liquid crystal display device and method of manufacturing the same

This paper presents two types of nonlinear controllers for an autonomous quadrotor helicopter. One type, a feedback linearization controller involves high-order derivative terms and turns out to be quite sensitive to sensor noise as well as modeling uncertainty. The second type involves a new approach to an adaptive sliding mode controller using input augmentation in order to account for the underactuated property of the helicopter, sensor noise, and uncertainty without using control inputs of large magnitude. The sliding mode controller performs very well under noisy conditions, and adaptation can effectively estimate uncertainty such as ground effects.

Feedback linearization vs. adaptive sliding mode control for a quadrotor helicopter

This article presents a survey on publicly available open-source projects (OSPs) on quadrotor unmanned aerial vehicles (UAVs). Recently, there has been increasing interest in quadrotor UAVs. Exciting videos have been published on the Internet by many research groups and have attracted much attention from the public [1][7]. Relatively simple structures of quadrotors has promoted interest from academia, UAV industries, and radio-control (RC) hobbyists alike. Unlike conventional helicopters, swashplates, which are prone to failure without constant maintenance, are not required. Furthermore, the diameter of individual rotors can be reduced as a result of the presence of four actuators [8].

Build Your Own Quadrotor: Open-Source Projects on Unmanned Aerial Vehicles

In this paper we describe a vision-based algorithm to control a vertical-takeoff-and-landing unmanned aerial vehicle while tracking and landing on a moving platform. Specifically, we use image-based visual servoing (IBVS) to track the platform in two-dimensional image space and generate a velocity reference command used as the input to an adaptive sliding mode controller. Compared with other vision-based control algorithms that reconstruct a full three-dimensional representation of the target, which requires precise depth estimation, IBVS is computationally cheaper since it is less sensitive to the depth estimation allowing for a faster method to obtain this estimate. To enhance velocity tracking of the sliding mode controller, an adaptive rule is described to account for the ground effect experienced during the maneuver. Finally, the IBVS algorithm integrated with the adaptive sliding mode controller for tracking and landing is validated in an experimental setup using a quadrotor.

Autonomous landing of a VTOL UAV on a moving platform using image-based visual servoing

Nonlinear PID control systems for a quadrotor UAV are proposed to follow an attitude tracking command and a position tracking command. The control systems are developed directly on the special Euclidean group to avoid singularities of minimal attitude representations or ambiguity of quaternions. A new form of integral control terms is proposed to guarantee almost global asymptotic stability when there exist uncertainties in the quadrotor dynamics. A rigorous mathematical proof is given. Numerical example illustrating a complex maneuver, and a preliminary experimental result are provided.

/pdf/geometric-nonlinear-pid-control-of-a-quadrotor-uav-on-se-3-1ac9brn334.pdf

Geometric nonlinear PID control of a quadrotor UAV on SE(3)

A Liquid Crystal Display (LCD) device and a method of manufacturing the same are provided. The liquid crystal molecules are inclined and rearranged in a radial shape by patterning upper and lower electrodes across and apart from each other on dummy pixels disposed on a black matrix formed in a non-display area of an LCD device and applying an electric field to a liquid crystal layer via the upper and lower electrodes. Thus, ion impurities in the non-display area can be prevented from dispersing to a display area, thereby improving edge part stains of the LCD device. The LCD device includes a first substrate including first pixel electrodes of the dummy pixels; a second substrate facing the first substrate and including first common electrodes formed across and apart from the first pixel electrodes; and a liquid crystal layer disposed between the first substrate and the second substrate, and having liquid crystal molecules rearranged by an electric field applied via the first pixel electrodes and the first common electrodes.

Daewon Lee

Papers

Feedback linearization vs. adaptive sliding mode control for a quadrotor helicopter

Build Your Own Quadrotor: Open-Source Projects on Unmanned Aerial Vehicles

Autonomous landing of a VTOL UAV on a moving platform using image-based visual servoing

Geometric nonlinear PID control of a quadrotor UAV on SE(3)

Liquid crystal display device and method of manufacturing the same