In this spring, the worst drought to hit China's northern wheat-growing belt in half a century. How to make proper
decision to fight drought is a vital problem to Chinese government. Of course, this is a complicated problem for many
factors involved. But for surveyor, we must provide the drought area, different drought levels and position information
quickly. Real Time Kinematic (RTK) satellite navigation is a technique used in land survey and in hydrographic survey
based on the use of carrier phase measurements of the GPS, GLONASS and/or Galileo signals where a single reference
station provides the real-time corrections of even to a centimetre level of accuracy. In this paper, we discuss the
application of GPS technology in fighting drought. Firstly, we introduce the RTK technology and its applications in
other field. Secondly, according to the requirement of fighting drought, we give the scheme of how to get the information
of drought area, different drought levels rapidly. Thirdly, we discuss the technology of real-time positioning to artificial
rainfall using aeroplane.
Along with the rapid development of modern space science, it is becoming a hot topic to use network spacecrafts for
deep space detection or earth observation. And that autonomous relative navigation is one of key technologies for
network spacecraft system. In this paper, we now propose a new autonomous relative navigation algorithm for network
spacecraft system with quaternion. In this abstract, we just add some pertinent remarks to listing the main work of this
paper: (1) a 3-D line and its transformation can be described by using dual quaternion finely. Moreover, the algorithm
with dual quaternion is used to calculate both relative position and attitude organically. So in the first topic section, how
to depict a 3-D line and its transformation with dual quaternion will be introduced; (2) in second topic section, the
thought of how to select the state valuable will be expatiated here firstly, and then we built the state equation state
equation according to Clohessy-Wiltshire (C-W) equation and quaternion differential equation; (3) in this paper, the state
valuable and the observation valuable are inconsistent for the observation unit is feature line. So how to build the
relationship between the state valuable and the observation valuable is very important. Here through the observation
transition matrix, we build the observation equation according to con-line equation of vision navigation; (4) finally, we
give an example about network spacecraft system. The simulation results show that proposed algorithm is valid for
network spacecraft system.
It is a valid way to implement some difficult space operations by distributed spacecraft system. Relative Positioning and
posing is one of key technologies for distributed spacecraft system. A special algebra of Rodrigues parameters is defined
for better description of attitude motion and coordinate transformation. In this paper, on the basis of the theories of
Rodrigues parameters, Extended Kalman Filtering (EKF) and the attitude dynamics of spacecraft, a relative positioning
and posing algorithm for distributed spacecraft system based-on Rodrigues parameters is proposed. Firstly, state equation
is built according to C-W equation and Rodrigues parameters differential equation. Secondly, observation equation is
built according to con-line equation of vision navigation. Finally, some simulations are done in order to demonstrate this
algorithm. The simulation results show that proposed algorithm is valid for distributed spacecraft system.
Celestial Navigation System (CNS), Inertial Navigation System (INS), Global Navigation Satellite System (GNSS), such
as GPS, GLONASS, GALILEO and Compass etc, and the integrations of them are some methods of autonomous
navigation for space. But these methods must be depended on the high speed links of the communications network.
Moreover, the precision of CNS is always worse, and can not meet the rigorous requirement of the space activities. INS
can not be used for long-term space navigation applications for its errors being accumulated. High accuracy can be met
by Carrier Differential Global Positioning System (CDGPS), but it is difficult to calculate the ambiguities of CDGPS.
Fortunately, autonomous relative navigation based on machine vision is a direction all over the world currently, and is
very suitable for autonomous spacecraft navigation because it has some advantages, such as low-cost, high precision,
autonomous ability, easy practicality etc. In this paper, on the basis of the attitude dynamics of spacecrafts and the theory
of machine vision, an autonomous relative navigation algorithm for spacecrafts based on dual quaternion and EKF is
proposed. The basis transform unit of this algorithm is feature line. Moreover, this algorithm is used to calculate both
relative position and attitude organically, and the disadvantages of those algorithms, in which, relative position and
attitude must be deal with separately, are overcome. Finally, the simulations show that this algorithm is an accurate valid
method for space navigation applications.