Onboard CCD Camera Research Articles

Nanosatellite optical downlink experiment: design, simulation, and prototyping

The nanosatellite optical downlink experiment (NODE) implements a free-space optical communications (lasercom) capability on a CubeSat platform that can support low earth orbit (LEO) to ground downlink rates>10 Mbps. A primary goal of NODE is to leverage commercially available technologies to provide a scalable and cost-effective alternative to radio-frequency-based communications. The NODE transmitter uses a 200-mW 1550-nm master-oscillator power-amplifier design using power-efficient M-ary pulse position modulation. To facilitate pointing the 0.12-deg downlink beam, NODE augments spacecraft body pointing with a microelectromechanical fast steering mirror (FSM) and uses an 850-nm uplink beacon to an onboard CCD camera. The 30-cm aperture ground telescope uses an infrared camera and FSM for tracking to an avalanche photodiode detector-based receiver. Here, we describe our approach to transition prototype transmitter and receiver designs to a full end-to-end CubeSat-scale system. This includes link budget refinement, drive electronics miniaturization, packaging reduction, improvements to pointing and attitude estimation, implementation of modulation, coding, and interleaving, and ground station receiver design. We capture trades and technology development needs and outline plans for integrated system ground testing.

Development of low-noise high-speed analog ASIC for X-ray CCD cameras and wide-band X-ray imaging sensors

We report on the development and performance evaluation of the mixed-signal Application Specific Integrated Circuit (ASIC) developed for the signal processing of onboard X-ray CCD cameras and various types of X-ray imaging sensors in astrophysics. The quick and low-noise readout is essential for the pile-up free imaging spectroscopy with a future X-ray telescope. Our goal is the readout noise of 5e−r.m.s. at the pixel rate of 1Mpix/s that is about 10times faster than those of the currently working detectors. We successfully developed a low-noise ASIC as the front-end electronics of the Soft X-ray Imager onboard Hitomi that was launched on February 17, 2016. However, it has two analog-to-digital converters per chain due to the limited processing speed and hence we need to correct the difference of gain to obtain the X-ray spectra. Furthermore, its input equivalent noise performance is not satisfactory (>100μV) at the pixel rate higher than 500kpix/s. Then we upgrade the design of the ASIC with the fourth-order ΔΣ modulators to enhance its inherent noise-shaping performance. Its performance is measured using pseudo CCD signals with variable processing speed. Although its input equivalent noise is comparable with the conventional one, the integrated non-linearity (0.1%) improves to about the half of that of the conventional one. The radiation tolerance is also measured with regard to the total ionizing dose effect and the single event latch-up using protons and Xenon, respectively. The former experiment shows that all of the performances does not change after imposing the dose corresponding to 590years in a low earth orbit. We also put the upper limit on the frequency of the latch-up to be once per 48years.

Eye Gesture Analysis with Head Movement for Advanced Driver Assistance Systems

Road traffic accidents are a major cause of death worldwide. In an attempt to reduce accidents, some research efforts have focused on creating Advanced Driver Assistance Systems (ADAS) able to detect vehicle, driver and environmental conditions and to use this information to identify cues for potential accidents. This paper presents continued work on a novel Non-intrusive Intelligent Driver Assistance and Safety System (Ni-DASS) for assessing driver point of regard within vehicles. It uses an onboard CCD camera to observe the driver’s face. A template matching approach is used to compare the driver’s eye-gaze pattern with a set of eye-gesture templates of the driver looking at different focal points within the vehicle. The windscreen is divided into cells and comparison of the driver’s eye-gaze pattern with templates of a driver’s eyes looking at each cell is used to determine the driver’s point of regard on the windscreen. Results indicate that the proposed technique could be useful in situations where low resolution estimates of driver point of regard are adequate. For instance, To allow ADAS systems to alert the driver if he/she has positively failed to observe a hazard.

Overall scheme and on-orbit images of Chang’E-2 lunar satellite CCD stereo camera

The goals of engineering and scientific missions for Chang’E-2 lunar satellite require high detection sensitivity and large imaging dynamic range for the onboard CCD cameras. The TDI CCD image sensor was adopted for the two linear CCD stereo cameras for the first time in the lunar reconnaissance of the world. The design argumentation is described in this paper. The analysis shows that the imagers meet the mission requirements. The satellite was launched on 1 October 2010 at zero window. The cameras obtained images of 7 m resolution on the 100 km orbit for the first time on 24 October 2010, and operated once again on 27 October 2010 to take stereo images of the Sinus Iridum with the resolution better than 1.5 m. On the near-moon-arc of 15 km×100 km elliptical orbit, the images are very clear and rich of grey scales, indicating successful completion of the Chang’E-2 engineering mission. At the present the cameras are acquiring the full lunar surface stereo images with 7 m resolution on the 100 km circular orbit to complete their scientific mission.

Vision-based control for rigid body stabilization

This paper addresses the problem of stabilizing to a desired equilibrium point an eye-in-hand system, which consists of a single camera mounted on a rigid body free to move on SE ( 3 ) . It is assumed that there is a collection of landmarks fixed in the environment and that the image coordinates of those landmarks are provided to the system by an on-board CCD camera. The proposed method addresses not only the problem of stabilization but also that of maintaining feature visibility along the system’s trajectory. The resulting solution consists of a feedback control law based on the current and desired image coordinates and reconstructed attitude and depth ratio information, which guarantees that (i) the desired equilibrium point is an almost global attractor; (ii) a set of necessary conditions for feature visibility holds throughout the system’s trajectories; and (iii) the image of a predefined feature point is kept inside the camera’s field of view.

Reconstruction of 3D contour with an active laser-vision robotic system

This paper presents a 3D contour reconstruction approach employing a wheeled mobile robot equipped with an active laser-vision system. With observation from an onboard CCD camera, a laser line projector fixed-mounted below the camera is used for detecting the bottom shape of an object while an actively-controlled upper laser line projector is utilized for 3D contour reconstruction. The mobile robot is driven to move around the object by a visual servoing and localization technique while the 3D contour of the object is being reconstructed based on the 2D image of the projected laser line. Asymptotical convergence of the closed-loop system has been established. The proposed algorithm also has been used experimentally with a Dr Robot X80sv mobile robot upgraded with the low-cost active laser-vision system, thereby demonstrating effective real-time performance. This seemingly novel laser-vision robotic system can be applied further in unknown environments for obstacle avoidance and guidance control tasks. Copyright © 2011 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society

多重構造ニュラルネットワークを用いた車載センサ情報統合に基づく車種認識

An algorithm of vehicle type recognition integrating on-board sensor information is proposed. This method, compensates for apparent size differences due to the objective distances of on-board sensors, the distance and intensity detected by a scanning laser radar, and the images input from an on-board CCD camera. A frame recognition which consists of a multiplex structured neural network using the three kinds of adjusted data is performed, then the results are integrated to improve the accuracy of the recognition of each object. Experiments using road images captured while driving and the sensing data show that this method is effective : average recognition rates were above 96.1% for various road environments.

Microarcsecond astrometry with Gaia: the solar system, the Galaxy and beyond

Gaia is an all-sky, high precision astrometric and photometric satellite of the European Space Agency (ESA) due for launch in 2010. Its primary mission is to study the composition, formation and evolution of our Galaxy. Over the course of its five-year mission, Gaia will measure parallaxes and proper motions of every object in the sky brighter than visual magnitude 20, amounting to a billion stars, galaxies, quasars and solar system objects. It will achieve an astrometric accuracy of 10 17. To characterize the objects (which are detected in real time, thus dispensing with the need for an input catalogue), each object is observed in 15 medium and broad photometric bands with an onboard CCD camera. With these capabilities, Gaia will make significant advances in a wide range of astrophysical topics. In addition to producing a detailed kinematical map of stellar populations across our Galaxy, Gaia will also study stellar structure and evolution, discover and characterise thousands of exoplanetary systems (extending down to about ten Earth masses for the nearest systems) and make accurate tests of General Relativity on large scales, to mention just some areas. I give an overview of the mission, its operating principles and its expected scientific contributions. For the latter I provide a quick look in five areas on increasing scale size in the universe: the solar system, exosolar planets, stellar clusters and associations, Galactic structure and extragalactic astronomy.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Fuzzy Lane-Track Control for the Automatic Guidance of an Automotive Vehicle

A Fuzzy Lane-track Controller called RPV is presented in this paper. Putting the emphasis as much on safety as on driving comfort, the aim of this study was the design of a driver assistance that would ensure a guidance function along a “virtual rail”, while any time allowing the driver to take over the controls. A fuzzy controller was designed and embedded on a Renault Safrane to perform the lateral control of the vehicle.An on-board CCD camera and image processing software and a gyroscope deliver the necessary information to the controller (lateral displacement, lateral speed, yaw rate). From these data, the fuzzy controller outputs a value of torque variation, which is applied to the steering column by means of a coaxial electric motor.Full-size field experiment yield encouraging results: on one hand, the lane-track controller induces a nonoscillating, smooth and comfortable trajectory in situations where the driver does not steer the test vehicle (hands free); on the other hand, RPV generates a noticeable feeling of confidence and assistance when the driver keeps his hands on the steering wheel.

Multi-modal human-robot interface for interaction with a remotely operating mobile service robot

This paper discusses requirements for information exchange between a human operator and a semi-autonomous service robot operating in a remote indoor environment. The resulting multimodal HuMan-Robot Interface (MRI) allows specification of various types of robot activities by use of an advanced system for natural spoken user-independent speech understanding and flexible robot command generation. Visual screen-based monitoring and support of complex operations is achieved by means of an animated three-dimensional environmental model augmented by the image of an onboard CCD camera. Typical features of the MRI are demonstrated through experiments performed with the mobile manipulator ROMAN.