Guidance system

About: Guidance system is a research topic. Over the lifetime, 4282 publications have been published within this topic receiving 45964 citations.

Evaluation of the use of low-cost GPS receivers in the autonomous guidance of agricultural tractors.

Abstract: This paper evaluates the use of low-cost global positioning system (GPS) receivers in the autonomous guidance of agricultural tractors. An autonomous guidance system was installed in a 6400 John Deere agricultural tractor. A lowcost GPS receiver was used as positioning sensor. Three different control laws were implemented in order to evaluate the autonomous guidance of the tractor with the low-cost receiver. The guidance was experimentally tested with the tracking of straight trajectories and with the step response. The total guidance error was obtained from the receiver accuracy and from the guidance error. For the evaluation of the receiver’s accuracy, positioning data from several lowcost receivers were recorded and analyzed. For the evaluation of the guidance error, tests were performed with each control law at three different speeds. The conclusions obtained were that relative accuracy of low-cost receivers decreases with the time; that for an interval lower than 15 min, the error usually remains below 1 m; that all the control laws have a similar behavior and it is conditioned by the control law adjustment; that automatic guidance with lowcost receivers is possible with speeds that went up to 9 km h–1; and finally, that the total error in the guidance is mainly determined by the receiver’s accuracy.

Mapping 3D guidance performance using approximate optimal cost-to-go function

Abstract: Being able to define and measure the performance of guidance systems is fundamental to their proper development. This task is particularly challenging for unmanned aerial vehicles operating in complex spatial environment like cities or mountains, both of which are operational theaters of predilection. Previous research mainly focuses on relative performance metrics. This paper, introduces a framework to derive absolute metrics. The approach is based on the idea that many guidance problems have a meaningful formulation as an optimal control problem. Hence the idea is that absolute performance metrics can be based on an approximation of the optimal control problem. In the following we approximate the vehicle dynamics using motion primitives. The choice of motion primitives is based on an analysis of the vehicle flight performance based on experimental data. As performance metric, we use the approximate cost-to-go maps and associated optimal states computed via dynamic programming for a cell-based world representation. The cost-to-go map, which can be computed for any environment described by Digital Terrain Elevation Data (DTED), provides a comprehensive insight into the interrelation of space, optimal behavior, as driven by a user specified performance index. The only limitation in the choice of performance index is that it should be a function of attributes of the finite state motion primitives. The paper illustrates the method applied to an unmanned R-MAX helicopter (10ft rotor diameter) operating in the down town of San Francisco. Three performance indexes are analyzed: time, energy and length.

In-Flight Assessment of a Pursuit Guidance Display Format for Manually Flown Precision Instrument Approaches

Abstract: In-flight evaluations of a pursuit guidance display system for manually flown precision instrument approaches were performed. The guidance system was integrated into the RASCAL JUH-60A Black Hawk helicopter. The applicability of the pursuit guidance disp1aFs to the operation of Runway Independent Aircraft (RIA) is made evident because the displays allow the pilot to fly a complex, multi-segment, descending, decelerating approach trajectory. The complex trajectory chosen for this in-flight assessment began from a downwind abeam position at 110 knots and was hand-flown to a 50 ft decision altitude at 40 knots using a rate-command/attitude-hold plus turn-coordination control system. The elements of the pursuit guidance format displayed on a 10-inch liquid crystal display (LCD) flat panel consisted of a flightpath vector and a "leader" aircraft as the pursuit guidance element. Approach guidance was based primarily on carrier-phase differential Global Positioning System (GPS) navigation, and secondarily on both medium accuracy inertial navigation unit states and air data computer states. Required Navigation Performance (RNP) concepts were applied to the construction of display elements such as lateral/vertical deviation indicators and a tunnel that indicated to the pilot, in real-time, the performance with respect to RNP error bounds. The results of the flight evaluations of the guidance display show that precise path control for operating within tight RNP boundaries (RNP 0.007NM/24ft for initial approach, RNP 0.008NM/19ft for intermediate approach, and RNP 0.002NM/9ft for final approach) is attainable with minimal to moderate pilot workload.

Guidance system and navigation method

Abstract: The invention relates to a navigation method for a pedestrian zone in public buildings, building complexes and traffic zones that comprise a plurality of destinations interlinked by traffic routes According to said method, continuous optical guidance lines are disposed along the traffic routes These guidance lines are associated with a destination, terminate at the associated destination and can be easily distinguished The guidance lines are provided with unambiguous optical direction-indicating features that point into the direction of the destination associated therewith The guidance lines are particularly remote-controlled and combined from partially selectively activated display devices Remote control is especially carried out by a control center via a network to which the controllers controlling the display devices are connected Information terminals are provided at well accessible locations and users can be identified and user data accessed at these terminals, especially in combination with an information system that outputs user-specific information at selected locations of the buildings, traffic routes and destinations Users can be identified by means of electronic data carriers such as transponders that can be contactlessly queried

Vision‐based obstacle detection for rotorcraft flight

Abstract: An obstacle detection approach to rotorcraft flight is described which is based on feature tracking and recursive range estimation. Flight characteristics are taken into account. A range map derived on the basis of this approach provides an advisory display to the pilot and can serve as input to an automatic obstacle-avoidance guidance system. A NASA CH-47 Chinook helicopter was used to develop an image and rotorcraft flight data base for verification of obstacle detection concepts. The performance of the passive range estimation algorithms is demonstrated using both laboratory image and flight image data.