提出采用一种3层改进型快速BP神经网络(Modified fast BP neural network,MFBPNN)求解一个5自由度多关节机器人逆向运动学问题。使用正向运动学计算获得的样本向量进行离线学习,然后充分利用人工神经网络的泛化特性,实现了机器人末端作用器位姿到各个关节转角变量之间的非线性映射。仿真结果表明,采用MFBPNN算法以后,绝对误差不超过0.005°,计算精度和处理速度能够满足机器人实时控制的要求,并且可以应用于机器人路径规划控制场合。 相似文献
In the present analysis, the mass spectrometer data from the ISS-b satellite, available in the form of contour plots at an average height of 1100 km for every alternate hour, is used. This analysis showed some interesting results in terms of the diurnal variation of the transition heights; at times dominance of He+ over the other ions, and the seasonal variations of different constituents. In the development of ion composition models, it is suggested that this type of result should be taken into consideration. 相似文献
Significant progress has been achieved in India in demonstrating the utility of remote sensing data for various oceanographic applications during the last one decade. Among these, techniques have been developed for retrieval of ocean surface waves, winds, wave forecast model, internal waves, sea surface temperature and chlorophyll pigments. Encouraged from these results as well as for meeting the specific and increasing data requirements on an assured basis by oceanographers, India is making concerted efforts for developing and launching state-of-the-art indigenous satellites for ocean applications in the coming years.
The first in the series of ocean satellites planned for launch is Oceansat-1 (IRS-P4) by early 1999. Oceansat-1 carries on-board an Ocean Colour Monitor (OCM) and a Multi-frequency Scanning Microwave Radiometer (MSMR). OCM will have 8 narrow spectral bands operating in visible and near- infrared bands (402–885 nm) with a spatial resolution of 360 m and swath of 1420 km. The MSMR with its all weather capability is configured to have measurements at 4 frequencies viz., 6.6, 10.65, 18 & 21 GHz in dual polarisation mode with a spatial resolution of 120, 80, 40 & 40 km, respectively with an overall swath of 1360 km. The Oceansat-1 with repetitivity of once in two days will provide global data for retrieval of various oceanographic and meteorological parameters such as chlorophyll (primary productivity), sea surface temperature and wind speed, besides a host of other parameters of relevance to meteorology.
A full fledged satellite for ocean applications known as Oceansat-2 (IRS-P7) is also planned for launch during 2002. This satellite with payload mix of microwave (Scatterometer, Altimeter & Passive Microwave Radiometer), Thermal (TIR) and Optical (OCM) sensors, will provide greater in-sight into the global understanding of ocean dynamics/resources. This mission is expected to provide a complete set of oceanographic measurements, which are useful for providing operational oceanographic services.
Efforts are also on towards development of missions having multi-frequency, multipolarisation and multi-look angle microwave payloads including Synthetic Aperture Radar (SAR) and advanced millimeter wave sounders, besides development of imaging spectrometers by 2005.
A well-knit plan has been initiated in India for utilisation of planned Oceansat data. Important efforts initiated in this direction include SATellite Coastal and Oceanographic Research and Ocean Information Services, which are being carried out on an integrated basis aiming at providing services to the down stream users. The paper highlights these efforts in India towards providing an operational ocean information services in the coming years. 相似文献
The Indian sector encompasses the equatorial and low latitude regions where the ionosphere is highly dynamic and is characterized by the equatorial ionization anomaly (EIA) resulting in large latitudinal electron density gradients causing errors and uncertainties in the estimation of range delays in satellite based navigation systems. The diurnal and seasonal variations of standard deviations in the TEC data measured during the low sunspot period 2004–2005 at 10 different Indian stations located from equator to the anomaly crest region and beyond are examined and presented. The day-to-day variability in TEC is found to be lowest at the equatorial station and increases with latitude up to the crest region of EIA and decreases beyond. 相似文献
It is shown that the optimal guidance problem can be handled as a Bolza-type problem which can be solved by straightforward calculation. The solution proves to be different from that given by Yang, et al. (1989) and is verified to be a minimum performance index solution. Also presented is an alternate unified approach to the solution of the nonlinear system of differential equation of the generalized proportional navigation law discussed earlier by Yang, et al. This unified equation has been solved for all the different cases of proportional navigation for which closed-form solutions have been published by earlier authors 相似文献