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Thesis - Leigh Moody.pdf - Bad Request - Cranfield University

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Appendix C / Axis Transforms<br />

_ _<br />

16.4 Transformation Between Co-ordinate Systems<br />

16.4.1 Co-ordinate Systems<br />

Three types of co-ordinates are defined for dealing with the position of<br />

points in E 3 with respect to a frame: Rectangular, Spherical Polar and UVR.<br />

Using generic co-ordinates for specifying algorithms is permissible<br />

providing that they have been previously defined using the full notation and<br />

their scope is clearly identified. Cartesian, Spherical Polar and Radar UVR<br />

co-ordinate systems are denoted by (C), (S) and (R) respectively.<br />

16.4.2 Cartesian (Rectangular) Co-ordinates<br />

The position of (p) in Rectangular co-ordinates with respect to frame (A)<br />

located at (a),<br />

XA YA ZA<br />

( x , y , z ) ≡ ( P , P , P )<br />

16-7<br />

a,<br />

b<br />

a,<br />

b<br />

a,<br />

b<br />

Equation 16.4-1<br />

The position of a point in E 3 is only equal to Rectangular co-ordinates since<br />

these are measured in a direction coincident with the unit vectors defining<br />

the frame. Rectangular co-ordinates form a vector in its strictest sense,<br />

whereas all other co-ordinates are defined in terms of ordered sets (triplets<br />

in E 3 ).<br />

16.4.3 Spherical Polar Co-ordinates<br />

If frame (B) located at point (p) is rotated through Euler YP angles such that<br />

X B passes through point (p) the polar co-ordinates with respect to frame (A),<br />

⎛<br />

⎜<br />

⎝<br />

P<br />

A<br />

b<br />

• P<br />

A<br />

b<br />

B B<br />

( P , Θ , Ψ )<br />

,<br />

a,<br />

b<br />

− tan<br />

−1<br />

A<br />

⎛ P<br />

⎜<br />

⎝ P<br />

ZA<br />

b<br />

hA<br />

b<br />

⎞<br />

⎟<br />

⎠<br />

A<br />

,<br />

: =<br />

tan<br />

−1<br />

⎛ P<br />

⎜<br />

⎝ P<br />

YA<br />

b<br />

XA<br />

b<br />

⎞ ⎞<br />

⎟ ⎟<br />

⎟ ⎟<br />

⎠ ⎠<br />

Equation 16.4-2<br />

The inverse transformation from Spherical Polar to Cartesian co-ordinates,<br />

A<br />

b<br />

( ) T<br />

B B<br />

B B<br />

B<br />

P ⋅ cΨ<br />

⋅ cΘ<br />

, P ⋅ sΨ<br />

⋅ cΘ<br />

, − P ⋅ s<br />

P : =<br />

Θ<br />

a,<br />

b<br />

16.4.4 UVR Co-ordinates<br />

A<br />

A<br />

a,<br />

b<br />

A<br />

A<br />

a,<br />

b<br />

A<br />

Equation 16.4-3<br />

The relationship between the position of point (p) in UVR and Rectangular<br />

co-ordinates is,

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