Airbus Defence and Space Sas

Matra Marconi Space France

Centre National Detudes Spatiales

Matra Marconi Space France Sa

Bernard Polle

Johan Montel

Olivier Lambeaux

Benoit Hanin

Renaud Broquet

Philippe Pham

Marcel Billand

A method for estimating the motion of a carrier with respect to an environment in relation to which the carrier is moving. The carrier bearing a navigation sensor and a vision sensor producing images of the environment. In the images acquired by the vision sensor, the characteristic elements of the images representing characteristic elements of the environment are identified. At least one condensed measurement is calculated as a function of characteristic elements of at least two images acquired at different instants. The motion of the carrier by a navigation filter is estimated, as a function of navigation measurements carried out and as a function of the condensed measurement. The condensed measurement is calculated as a function furthermore of a priori estimation of the motion, as provided by the navigation filter.

Method of estimating the motion of a carrier with respect to an environment and calculation device for navigation system

A method for calibrating spatial errors induced by phase biases having a detrimental effect on the measurements of phase differences of radio signals received by three unaligned receiving antennas of a vehicle. An inter-satellite angular deviation of a pair of satellites is estimated in two different ways: on the basis of the respective positions of the vehicle and of the satellites to obtain a theoretical inter-satellite angular deviation; and on the basis of the respective directions of incidence of the satellites relative to the vehicle, which are determined from phase measurements, to obtain an estimated inter-satellite angular deviation. The space errors are estimated on the basis of said theoretical and estimated inter-satellite angular deviations. Also, a method and system for estimating the attitude of a vehicle, in particular a spacecraft.

Method for calibrating spatial errors, and method and system for estimating the attitude of a vehicle

A method of controlling the attitude of a satellite in orbit around a celestial body. The attitude of the satellite being controlled by a momentum storage device and controllable surfaces of the satellite configured to create desaturation torques in the storage device by using solar pressure. The controllable surfaces are arranged on solar panels mobile in rotation around an axis Y. At least one electric thruster configured to control the orbit of the satellite also controls the attitude of the satellite. The orientation of the electric thruster is controlled to activate the electric thruster with a thrust direction deliberately not aligned with a center of mass of the satellite to create desaturation torques in the storage device along axis Y. The controllable surfaces are controlled to create desaturation torques of the storage device in a plane orthogonal to the Y axis.

Method of controlling the attitude of a satellite and an attitude-controlled satellite

A satellite has a platform of elongated shape in a direction parallel to a roll axis of the satellite. A deployable arm is pivotally carried by a longitudinally extending face of the platform. A solar generator is carried at the end of the arm by a first motor for aiming the generator through a range of 360&deg; about a pitch axis orthogonal to the direction of elongation of the platform. A second motor rotates the solar generator through a limited angular range about an axis that is orthogonal to the pitch axis and parallel to the plane of the generator. The arm, when deployed, moves the solar generator away from on a stored position in contact with the platform in a direction of a yaw axis.

Satellite having a solar generator on a deployable arm, and method of bringing such a satellite on station

An earth orbiting satellite is enabled to assume a 'survival mode' of operation in which its x axis is aligned with the sun by observing characteristics of the movement of the frame of the satellite (e.g. its x axis) relative to the sun and performing calculations based on those operations. A more accurate result is achieved if a deliberate offset is introduced between the mean direction of the x axis and the sun's direction. The control arrangement for positioning the x axis with this offset is preferably adaptive, resulting in control of the satellite's thrusters so as to produce oscillation of the x axis in a way which allows suitable measurements to be taken.

Controlling rotation of a spacecraft

The attitude of a satellite placed on a non-heliosynchronous earth orbit in a plane that is inclined relative to the equatorial plane of the earth is controlled for efficient use of solar panels and radiators. The satellite has a structure, solar panels apt to be rotated with respect to the structure rotation and two opposed radiators each fixed on one of two opposed faces of the satellite structure which are orthogonal to the rotation axis. One of the radiators has greater emissivity than the other. A yaw axis bound to the structure satellite and orthogonal to rotation axis is aimed towards the earth. The solar panels of the satellite are maintained in an optimum orientation relative to the sun by rotating them. At least during periods of each year when an angle .beta. between a sun-earth direction and the plane of the satellite orbit lies between two predetermined values, the satellite structure is rotated about the yaw axis to maintain the radiators in a plane parallel to a direction toward the sun so long as the satellite is remote from an orthogonal projection of the sun direction onto the satellite orbit plane. The orientation of the satellite structure is reversed when necessary to ensure that the radiator of higher emissivity is in shadow.

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Saint-Orens, France

Bernard Polle