Development of a multiaxial force sensor for docking systems characterization

This thesis presents the development of a multi-axial force sensor (MAFS) designed specifically for docking systems. Docking between two satellites occurs when the probe of the chaser satellite connects with the drogue of the target satellite. In order to better understand this dynamic process, it is crucial to measure the forces exchanged between the probe and drogue during impact. The MAFS developed in this research is capable of measuring dynamic loads in two directions and at an appropriate sampling rate, providing valuable insights on the impact dynamics. The construction of the MAFS involves the use of 3D printed joints, milled plates, and four load cells. Two load cells are responsible for measuring frontal loads, while the remaining two measure lateral loads. The output signals from the load cells are amplified and acquired through an analog-to-digital converter. To establish the relationship between force and voltage, each load cell undergoes individual calibration using known weights, employing a linear model. Static tests are carried out in the frontal and lateral directions to verify the accuracy of the MAFS. The dynamic behavior of the MAFS is validated through a series of drop tests utilizing a pulley and drop weight setup, confirming the impulse momentum equivalence. For the dynamic tests, a high precision and high frequency motion capture system provides the positional data. Eventually, to test docking loads, the MAFS is mounted to the edge of a low-friction table, which replicates the low gravity conditions of satellite docking. Acting as the target, the MAFS interacts with a small satellite with gas cushions that floats on the table, serving as the chaser. The probe mounted on the MAFS collides with the drogue on the chaser, and the resulting loads are measured.