detumble

Implementation of detumbling for the Delfi-PQ. Repository aims to perform some sensor fusion using BMX-055. It finally aims to implement the B_dot detumbling algorithm to stabilize the satellite. Some of the code might be inherited from https://github.com/DelfiSpace

Branches to be diverged in future:

1. Accelerometer: tbd - filters cutoff
2. Gyroscope: tbd -
3. Magnetometer: IN PROGRESS: scroll below for status
4. Detumbling: IN PROGRESS: navigate here
5. Sensor fusion: tbd - understand quaternions, explore Kalman filter, sun sensor + magnetometer
6. Magnetorquer: tbd - perform self test closed loop (maybe even the thruster with acc)

current progress:

Interfaced BMX-055's magnetometer successfully with the MSP432-

• initialized in a good enough (alive) mode - 10 repetitions per axis
• factory trim read from flash and used in calibration
• temperature compensation for magnetometer fused with the readings (Outer Space doesn't comply, if Bosch provides temperature scaling, might as well use it)
• random and long expressions from Bosch's sensortec library implemented for magnetometer
• bias compensation done with Android's "draw a figure 8 method". i.e. bias = (min + max)/2
• one of the results illustrated below

Earth's magnetic field with BMX055, Soft and Hard Iron errors visible in plots below (ref: https://www.vectornav.com/support/library/magnetometer)

Muddy parts (not so sure - will reveal vulnerabilities in test)

• signed bit flip behaviour not checked strongly
• not still sure if resolutions and scaling is corresponding to actual uT values
• reset/i2c complications not studied yet
• soft reset yet to be implemented, in case ground station wants to give one more chance to ADCS
• API not coherently check for with MIPS and FLOPS
• possibilities of power saving modes not explored yet
• a strong + lite library far from implemented

repository file structure:

1. detumble_algo_msp: Source files for Hardware In Loop (HIL) tests of detumbling algo on MSP432.
2. detumble_algo_pc: Source files for detumbling algo meant to be compiled on VS/GCC on PC.
3. magnetometer_test: Source files for talking to the BMX using MSP432, (with trimming and temperature compensation)
4. plotters: Python and MATLAB scripts for performing HIL tests, magnetometer calibrations, plotting comparisons between MATLAB, PC and MSP.
5. uartecho_FPU: Parsing floats and interpreting newlines might be different for Windows and Linux. Source files in this folder facilitate early stage debugging before moving to HIL tests.