Hans-Ullrich Döhler

Simulation of Imaging Radar Using Graphics Hardware Acceleration

Extending previous works by Doehler and Bollmeyer we describe a new implementation of an imaging radar simulator. Our approach is based on using modern computer graphics hardware making heavy use of recent technologies like vertex and fragment shaders. Furthermore, to allow for a nearly realistic image we generate radar shadows implementing shadow map techniques in the programmable graphics hardware. The particular implementation is tailored to imitate millimeter wave (MMW) radar but could be extended for other types of radar systems easily.

A System is More Than the Sum of Its Parts - Conclusion of DLR'S Enhanced Vision Project "ADVISE-PRO"

Within its research project ADVISE-PRO (advanced visual system for situation awareness enhancement-prototype, 2003-2006) that will be presented in this contribution, DLR has combined elements of enhanced vision and synthetic vision to one integrated system to allow all low visibility operations independently from the infrastructure on ground. The core element of this system is the adequate fusion of all information that is available onboard. This fusion process is organized in a hierarchical manner. The most important subsystems are; a) the sensor based navigation which determines the aircrafts position relative to the runway by automatically analyzing sensor data (MMW, IR, radar altimeter) without using neither (D)GPS nor precise knowledge about the airport geometry, b) an integrity monitoring of navigation data and terrain data which verifies onboard navigation data ((D)GPS + INS) with sensor data (MMW-radar, IR-sensor, radar altimeter) and airport/terrain databases, c) an obstacle detection system and finally d) a consistent description of situation and respective HMI for the pilot

Developing an obstacle display for helicopter brownout situations

Project ALLFlight is DLRs initiative to diminish the problem of piloting helicopters in degraded visual conditions. The problem arises whenever dust or snow is stirred up during landing (brownout/whiteout), eectively blocking the crews vision of the landing site. A possible solution comprises the use of sensors that are able to look through the dust cloud. As part of the project display symbologies are being developed to enable the pilot to make use of the rather abstract and noisy sensor data. In a rst stage sensor data from very dierent sensors is fused. This step contains a classication of points into ground points and obstacle points. In a second step the result is augmented with ground data bases and depicted in a synthetic head-down display. Regarding the design, several variations in symbology are considered, including variations in color coding, continuous or non-continuous terrain displays and dierent obstacle representations. In this paper we present the basic techniques used for obstacle and ground separation. We choose a set of possibilities for the pilot display and detail the implementation. Furthermore, we present a pilot study, including human factors assessment with focus on usability and pilot acceptance.

An evaluation environment for a helmet-mounted synthetic degraded visual environment display

Degraded visual environment (DVE) is a term coined for environmental conditions that impair the visual orientation of a helicopter pilot during flight or landing. These conditions include brown-out, but also night, glare, fog and mist, as well as combinations of those. In order to assist pilots under DVE conditions DLR, the German Aerospace Center, initiated project ALLFlight. Using a combination of multi-sensor fusion, specialized symbologies for head-down and helmet-mounted display, and database augmentation the pilot should be enabled to safely operate the helicopter. Based on an earlier implementation of a synthetic head-down display an implementation for a head-tracked, helmet-mounted system is implemented. Since color is presently not an option for head-up displays, alternative symbologies have to be considered, including variations in transparency, density of terrain displays and size and shape variations for obstacle representation. In this paper we present a simulator setup for evaluating the display concepts developed. This includes various simulation stages for visual and sensor input and a flexible simulator cockpit for testing variations of display concepts. We detail the implementation architecture and present first evaluation details from a recent pilot study.

Evaluation of a “Stereo” Radar approach for terrain reconstruction using synthetic data

Enhanced vision systems (EVS) are a possibility to improve the situation awareness of an aircrew during poor visibility conditions. EVS are based on sensor data which might be difficult to interpret especially for radar data. Fast scanning radar systems in the millimeter waveband (35 or 94 GHz) are commonly unable to measure the elevation of a target. Nevertheless these elevation data can sometimes be reconstructed from a series of images or from images taken from different viewpoints or bank angles. In case of forward looking millimeter wave radar it is more promising to use different bank angles. The authors have detailed these ideas using the term ldquoStereo Radarrdquo in previous publications. In this paper we take a closer look at the accuracy and the resolution of the algorithm. For this a series of experiments using synthetic data is performed. Furthermore we show the influence of size, elevation, shape, and different (radar) textures of a target on the reconstructed elevation. Finally some tests are carried out to demonstrate the robustness against different kinds of noise.

Integration of an Exocentric Orthogonal Coplanar 360 Degree Top View in a Head Worn See-Through Display Supporting Obstacle Awareness for Helicopter Operations

The objective was the development of an HMI for helicopter obstacle awareness and warning systems in order to improve the situational and spatial awareness as well as the workload of helicopter pilots. The related work concerning obstacle awareness and warning systems, situational awareness, orthogonal coplanar and perspective representations plus previous work done by DLR was depicted and discussed. The two main aspects of the developed HMI concept were explained, i.e., the combination of the exocentric orthogonal coplanar top view with the egocentric perspective view, and secondly three ways for the integration of the obstacle awareness display inside a head-worn see-through display. The developed HMI concept was applied to two helicopter offshore operations and its specific obstacle situation. The first operation is a hoist operation at the lower access point of an offshore wind turbine. The second regards the landing operation on an offshore platform. From a technical point of view, especially concerning available sensor technologies, helicopter might be fitted with obstacle awareness systems in future. The HMI design is still under investigation in order to support the pilot in a holistic and balanced way.

Review of conformal displays: more than a highway in the sky

Abstract. A head-worn display combined with accurate head-tracking allows one to show synthetically generated symbols in a way that they appear as a part of the real world. Depending on the specific research context, different terms have been used for the ability to show display elements as parts of the outside world. These include contact analog, scene linked, augmented reality, and outside conformal. While the famous highway in the sky was one of the first applications in avionics, over the years more and more conformal counterparts have been devised for aircraft-related instruments. Among them are routing information, navigation aids, specialized landing displays, obstacle warnings, drift indicators, and many more. Conformal displays have been developed for more than 40 years. We present a review of some results, as well as look ahead to research trends for the next years. We suggest that naturalism is not the best choice for the design of conformal displays. Instead, more abstract representations often yield better pilot acceptance.