Package org.orekit.utils

Class FieldAngularCoordinates<T extends CalculusFieldElement<T>>

    • Constructor Detail

      • FieldAngularCoordinates

        public FieldAngularCoordinates​(FieldRotation<T> rotation,
                               FieldVector3D<T> rotationRate)
        Builds a rotation/rotation rate pair.
        Parameters:
        rotation - rotation
        rotationRate - rotation rate Ω (rad/s)

      • FieldAngularCoordinates

        public FieldAngularCoordinates​(FieldRotation<T> rotation,
                               FieldVector3D<T> rotationRate,
                               FieldVector3D<T> rotationAcceleration)
        Builds a rotation / rotation rate / rotation acceleration triplet.
        Parameters:
        rotation - i.e. the orientation of the vehicle
        rotationRate - rotation rate Ω, i.e. the spin vector (rad/s)
        rotationAcceleration - angular acceleration vector dΩ/dt (rad/s²)

      • FieldAngularCoordinates

        public FieldAngularCoordinates​(FieldPVCoordinates<T> u1,
                               FieldPVCoordinates<T> u2,
                               FieldPVCoordinates<T> v1,
                               FieldPVCoordinates<T> v2,
                               double tolerance)
        Build the rotation that transforms a pair of pv coordinates into another one.

        WARNING! This method requires much more stringent assumptions on its parameters than the similar constructor from the FieldRotation class. As far as the FieldRotation constructor is concerned, the v₂ vector from the second pair can be slightly misaligned. The FieldRotation constructor will compensate for this misalignment and create a rotation that ensure v₁ = r(u₁) and v₂ ∈ plane (r(u₁), r(u₂)). THIS IS NOT TRUE ANYMORE IN THIS CLASS! As derivatives are involved and must be preserved, this constructor works only if the two pairs are fully consistent, i.e. if a rotation exists that fulfill all the requirements: v₁ = r(u₁), v₂ = r(u₂), dv₁/dt = dr(u₁)/dt, dv₂/dt = dr(u₂)/dt, d²v₁/dt² = d²r(u₁)/dt², d²v₂/dt² = d²r(u₂)/dt².

        Parameters:
        u1 - first vector of the origin pair
        u2 - second vector of the origin pair
        v1 - desired image of u1 by the rotation
        v2 - desired image of u2 by the rotation
        tolerance - relative tolerance factor used to check singularities

      • FieldAngularCoordinates

        public FieldAngularCoordinates​(Field<T> field,
                               AngularCoordinates ang)
        Builds a FieldAngularCoordinates from a field and a regular AngularCoordinates.
        Parameters:
        field - field for the components
        ang - AngularCoordinates to convert

      • FieldAngularCoordinates

        public FieldAngularCoordinates​(FieldRotation<U> r)
        Builds a FieldAngularCoordinates from a FieldRotation<FieldDerivativeStructure>.

        The rotation components must have time as their only derivation parameter and have consistent derivation orders.

        Type Parameters:
        U - type of the derivative
        Parameters:
        r - rotation with time-derivatives embedded within the coordinates
        Since:
        9.2

    • Method Detail

      • getIdentity

        public static <T extends CalculusFieldElement<T>> FieldAngularCoordinates<T> getIdentity​(Field<T> field)
        Fixed orientation parallel with reference frame (identity rotation, zero rotation rate and acceleration).
        Type Parameters:
        T - the type of the field elements
        Parameters:
        field - field for the components
        Returns:
        a new fixed orientation parallel with reference frame

      • estimateRate

        public static <T extends CalculusFieldElement<T>> FieldVector3D<T> estimateRate​(FieldRotation<T> start,
                                                                                FieldRotation<T> end,
                                                                                double dt)
        Estimate rotation rate between two orientations.

        Estimation is based on a simple fixed rate rotation during the time interval between the two orientations.

        Type Parameters:
        T - the type of the field elements
        Parameters:
        start - start orientation
        end - end orientation
        dt - time elapsed between the dates of the two orientations
        Returns:
        rotation rate allowing to go from start to end orientations

      • estimateRate

        public static <T extends CalculusFieldElement<T>> FieldVector3D<T> estimateRate​(FieldRotation<T> start,
                                                                                FieldRotation<T> end,
                                                                                T dt)
        Estimate rotation rate between two orientations.

        Estimation is based on a simple fixed rate rotation during the time interval between the two orientations.

        Type Parameters:
        T - the type of the field elements
        Parameters:
        start - start orientation
        end - end orientation
        dt - time elapsed between the dates of the two orientations
        Returns:
        rotation rate allowing to go from start to end orientations

      • revert

        public FieldAngularCoordinates<T> revert()
        Revert a rotation / rotation rate / rotation acceleration triplet.

        Build a triplet which reverse the effect of another triplet.

        Returns:
        a new triplet whose effect is the reverse of the effect of the instance

      • rotationShiftedBy

        public FieldRotation<T> rotationShiftedBy​(T dt)
        Get a time-shifted rotation. Same as shiftedBy(double) except only the shifted rotation is computed.

        The state can be slightly shifted to close dates. This shift is based on an approximate solution of the fixed acceleration motion. It is not intended as a replacement for proper attitude propagation but should be sufficient for either small time shifts or coarse accuracy.

        Parameters:
        dt - time shift in seconds
        Returns:
        a new state, shifted with respect to the instance (which is immutable)
        Since:
        11.2
        See Also:
        shiftedBy(CalculusFieldElement)

      • shiftedBy

        public FieldAngularCoordinates<T> shiftedBy​(double dt)
        Get a time-shifted state.

        The state can be slightly shifted to close dates. This shift is based on a simple quadratic model. It is not intended as a replacement for proper attitude propagation but should be sufficient for either small time shifts or coarse accuracy.

        Specified by:
        shiftedBy in interface TimeShiftable<T extends CalculusFieldElement<T>>
        Parameters:
        dt - time shift in seconds
        Returns:
        a new state, shifted with respect to the instance (which is immutable)

      • shiftedBy

        public FieldAngularCoordinates<T> shiftedBy​(T dt)
        Get a time-shifted state.

        The state can be slightly shifted to close dates. This shift is based on a simple quadratic model. It is not intended as a replacement for proper attitude propagation but should be sufficient for either small time shifts or coarse accuracy.

        Specified by:
        shiftedBy in interface FieldTimeShiftable<FieldAngularCoordinates<T extends CalculusFieldElement<T>>,​T extends CalculusFieldElement<T>>
        Parameters:
        dt - time shift in seconds
        Returns:
        a new state, shifted with respect to the instance (which is immutable)

      • getRotation

        public FieldRotation<T> getRotation()
        Get the rotation.
        Returns:
        the rotation.

      • getRotationRate

        public FieldVector3D<T> getRotationRate()
        Get the rotation rate.
        Returns:
        the rotation rate vector (rad/s).

      • getRotationAcceleration

        public FieldVector3D<T> getRotationAcceleration()
        Get the rotation acceleration.
        Returns:
        the rotation acceleration vector dΩ/dt (rad/s²).

      • addOffset

        public FieldAngularCoordinates<T> addOffset​(FieldAngularCoordinates<T> offset)
        Add an offset from the instance.

        We consider here that the offset rotation is applied first and the instance is applied afterward. Note that angular coordinates do not commute under this operation, i.e. a.addOffset(b) and b.addOffset(a) lead to different results in most cases.

        The two methods addOffset and subtractOffset are designed so that round trip applications are possible. This means that both ac1.subtractOffset(ac2).addOffset(ac2) and ac1.addOffset(ac2).subtractOffset(ac2) return angular coordinates equal to ac1.

        Parameters:
        offset - offset to subtract
        Returns:
        new instance, with offset subtracted
        See Also:
        subtractOffset(FieldAngularCoordinates)

      • subtractOffset

        public FieldAngularCoordinates<T> subtractOffset​(FieldAngularCoordinates<T> offset)
        Subtract an offset from the instance.

        We consider here that the offset Rotation is applied first and the instance is applied afterward. Note that angular coordinates do not commute under this operation, i.e. a.subtractOffset(b) and b.subtractOffset(a) lead to different results in most cases.

        The two methods addOffset and subtractOffset are designed so that round trip applications are possible. This means that both ac1.subtractOffset(ac2).addOffset(ac2) and ac1.addOffset(ac2).subtractOffset(ac2) return angular coordinates equal to ac1.

        Parameters:
        offset - offset to subtract
        Returns:
        new instance, with offset subtracted
        See Also:
        addOffset(FieldAngularCoordinates)

      • toAngularCoordinates

        public AngularCoordinates toAngularCoordinates()
        Convert to a regular angular coordinates.
        Returns:
        a regular angular coordinates

      • applyTo

        public FieldPVCoordinates<T> applyTo​(PVCoordinates pv)
        Apply the rotation to a pv coordinates.
        Parameters:
        pv - vector to apply the rotation to
        Returns:
        a new pv coordinates which is the image of pv by the rotation

      • applyTo

        public FieldPVCoordinates<T> applyTo​(FieldPVCoordinates<T> pv)
        Apply the rotation to a pv coordinates.
        Parameters:
        pv - vector to apply the rotation to
        Returns:
        a new pv coordinates which is the image of pv by the rotation
        Since:
        9.0

      • getModifiedRodrigues

        public T[][] getModifiedRodrigues​(double sign)
        Convert rotation, rate and acceleration to modified Rodrigues vector and derivatives.

        The modified Rodrigues vector is tan(θ/4) u where θ and u are the rotation angle and axis respectively.

        Parameters:
        sign - multiplicative sign for quaternion components
        Returns:
        modified Rodrigues vector and derivatives (vector on row 0, first derivative on row 1, second derivative on row 2)
        Since:
        9.0
        See Also:
        createFromModifiedRodrigues(CalculusFieldElement[][])

      • createFromModifiedRodrigues

        public static <T extends CalculusFieldElement<T>> FieldAngularCoordinates<T> createFromModifiedRodrigues​(T[][] r)
        Convert a modified Rodrigues vector and derivatives to angular coordinates.
        Type Parameters:
        T - the type of the field elements
        Parameters:
        r - modified Rodrigues vector (with first and second times derivatives)
        Returns:
        angular coordinates
        Since:
        9.0
        See Also:
        getModifiedRodrigues(double)