TAM Encoder Software

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Description

The purpose of this module is to act as an interface between a three-axis Magnetometer (TAM) sensor module and the flight software layer. A TAM will measure the local magnetic field in the local sensor frame $\mathcal{L}$, which may have some orientation relative to the body frame $\mathcal{B}$.

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Example Use Cases

• Get local magnetic field in the body frame: In reality, sensors are only able to measure the local orientation of fields in their frame (they have no knowledge of parent frames). This module transforms between the sensor frame and the body frame.

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Module Implementation

Given the DCM $[BL]$, which describes the rotation from $B\to L$, this module computes the body frame magnetic field ${}^{\mathcal{B}}\mathbf{B}$ as:

$${}^{\mathcal{B}}\mathbf{B}=[BL{]}^{\mathcal{L}}\mathbf{B}$$

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Assumptions/Limitations

• By default, $[BL]$ must be set by the user. This is to allow for improper configurations between the physical TAM orientation and the flight software’s knowledge of its orientation. Note that the TAM, and all physical objects, track their orientation relative to the root object (e.g. spacecraft ). This can be accessed by calling the DCM_LB method, which is equivalent to $[LB]$. To input the rotation, simply input $[LB{]}^T$ → DCM_LB.Transpose