Velocity Accumulation Tracking Software

SWITCH TO API

Description

The purpose of this module is to provide a first-order measurement of net $\Delta v$ that has occurred during a user-specified time period based on accelerometer measurements. It is intended to interface with an Accelerometer model as part of a translational determination software chain.

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Example Use Cases

• Measure accumulated $\Delta v$: This software provides a mechanism to measure reading from an accelerometer to compute accumulated $\Delta v$ generated from propulsion-type systems. These measurements can then be used to validate other behavior (e.g. turning off a propulsion system, confirming a maneuver) without accessing physics-based data (e.g. the spacecraft body state message, which also contains this information but is not accessible in reality).

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Module Implementation

The primary purpose of this module is to compute the accumulated change in spacecraft velocity over a measurement period, which is the time between resets of this software. To achieve this, the module receives and stores time-stamped packets from an attached accelerometer, where the accumulated $\Delta v$ is,

$$\Delta v=\sum _{i=1}^N{a}_i\Delta t$$

where $N$ is the number of stored packets and $a_i$ is the body frame $\mathcal{B}$ acceleration as measured by the IMU accelerometer module and $\Delta t=t_i-t_{n-1}$.

NOTE

$\Delta t$ is not the simulation timestep, as the module may be called at asynchronously relative to the dynamic simulation step.

To avoid growing computational expense as the number of IMU packets grows, the packets are ordered from newest to oldest, and only packets with time tags that satisfy $t_i>t_{n-1}$ are processed.

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Assumptions/Limitations

• The module assumes that all accelerometer measurements are provided in the body frame $\mathcal{B}$.