We evaluated the ability of GPS collars in eastern Hokkaido during August and September, 2000. We placed the collars in a range of three types of environment (i.e., Open-flat, Covered-flat, and ...Covered-steep) and compared the GPS location. Rate of success in getting positions were 97%, 45%, and 57%, respectively, in the collar made by Televilt, and 100%, 97%, and 94% in Lotek. Vegetation cover decreased the success of location attempts. Rate of 3-dimensional positions were 55%, 36%, and 18% in Televilt, 97%, 47%, and 66% in Lotek, affected by vegetation cover and topography. Positional error (mean±SD) were 48±32m in Televilt, and 35±30m, Lotek. There were no differences among the three environment. We placed a GPS collar on a free-ranging Hokkaido sika deer (Cervus nippon yesoensis) in Shiranuka Hills, Hokkaido, in March, 1999 and its recorded 39locations, 5% of attempt, after 1year. Animal-tracking by GPS is developing now and expected to be refined in its rate of success in locating positions and occurrences in positional error.
U radu se daju rezultati pojednostavljenja Douglas-Peuckerovim algoritmom linija s fiksnim točkama (točkama koje ne smiju biti uklonjene). Ispitivanja su provedena kako na linijama koje su prvo ...razlomljene na segmente od jedne do druge fiksne točke pa potom svaki taj segment posebno pojednostavljen, tako i na cijelim (nerazlomljenim) linijama s fiksnim točkama.
This paper presents a method of determining the statistical positional accuracy of a moving object being tracked by any 2D (but particularly radiolocation) positioning system without requiring a more ...accurate reference system. Commonly for testing performance only static positional errors are measured, but typically for radiolocation systems the positional performance is significantly different for moving objects compared with stationary objects. When only the overall statistical performance is required, the paper describes a measurement technique based on determining 1D cross-track errors from a nominal path, and then using this data set to determine the overall 2D positional error statistics. Comparison with simulated data shows that the method has good accuracy. The method is also tested with vehicle tracking in a city and people tracking within a building. For the indoor case, static and dynamic measurements allowed the degrading effect of body-worn devices due to signal blockage to be determined. Error modeling is also performed and a Rayleigh-Gamma model is proposed to describe the radial positional errors. It is shown that this model has a good match with both indoor and outdoor field measurements.
This paper presents an enhanced least-squares positioning algorithm for locating and tracking within indoor environments where multipath and nonline-of-sight propagation conditions predominate. The ...ranging errors are modeled as a zero-mean random component plus a bias component that is assumed to be a linear function of the range. Through minimizing the mean-square error of the position estimation, an expression for the optimal estimate of the bias parameter is obtained. Both range and pseudo-range-based positioning are considered. Simulations and experimentation are conducted which show that a significant accuracy gain can be achieved for range-based positioning using the enhanced least-squares algorithm. It is also observed that the pseudo-range-based least-squares algorithm is little affected by the choice of the bias parameter. The results demonstrate that the experimental 5.8-GHz ISM band positioning system can achieve positional accuracy of around half a meter when using the proposed algorithm.
Hole positional accuracy, which is important in drilling operations with automated machine tools, e.g. NC machining-centers, is examined by a special runout device. Positional deviation of a drilled ...hole from the spindle rotating axis is mostly determined at the beginning of penetration. This deviation is caused by the deflection of tool rotating axis around a certain point on chisel edge. The experimental results indicate the drill overhang length has a significant influence on the hole positional accuracy. A fine feed in start of drilling and a spiral type of drill point grinding are effective to reduce such deviation. Stub tooling system, which gives a strong bending rigidity of tool, is a desirable technique to improve the positional accuracy in drilling operations.
The primary objective of any navigation system is to provide accurate user position. Navigation with Indian Constellation (NavIC) is an emerging regional satellite navigation system being developed ...by ISRO, India. The positional accuracy of the NavIC depends upon various parameters based on the application. Doppler shift is one among those parameters which plays an important role in finding the user position in dynamic conditions. The effect of the Doppler shift is more in high dynamic applications like missiles launching, air navigation due to high relative velocity between receiver and satellite. In this Paper, an efficient algorithm is developed to estimate the Doppler positioning using least squares method in static and various dynamic conditions. For this, the experimental data acquired from Indian Regional Navigation Satellite System (IRNSS)-GPS receiver located at low latitude station (Hyderabad: 17.39˚N, 78.31˚E) is used. A trajectory path has been simulated to estimate the user position and its accuracy measures in low and high dynamic conditions. It is noticed that, Doppler shift vary ±1KHz for geosynchronous satellites in static conditions, whereas it is ±40KHz in high dynamics. It is observed the position error is high in high dynamics as compared with low dynamics because of the higher Doppler shifts.
PDF
