Pivot-Only Azimuthal Control and Attitude Estimation of Balloon-borne Payloads

TL;DR

The paper tackles high-rate azimuthal pointing for balloon-borne payloads with pivot-only actuation by coupling a bias-aware MEKF for attitude estimation with a PI yaw-rate controller. It shows that a simplified rigid-body model can capture the dominant dynamics, enabling stable, high-rate tracking without a reaction wheel. Numerical simulations demonstrate robust MEKF performance and controlled yaw dynamics under flight-like disturbances, while preliminary experiments validate pivot-only control in hardware. The results suggest a viable, lighter control architecture for fast sky-scanning missions, with future work focused on onboard MEKF implementation and integration with additional subsystems.

Abstract

This paper presents an attitude estimation and yaw-rate control framework for balloon-borne payloads using pivot-only actuation, motivated by the Taurus experiment. Taurus is a long-duration balloon instrument designed for rapid azimuthal scanning at approximately 30 deg/s using a motorized pivot at the flight-train connection, without a reaction wheel. We model the gondola as a rigid body subject to realistic disturbances and sensing limitations, and implement a Multiplicative Extended Kalman Filter (MEKF) that estimates attitude and gyroscope bias by fusing inertial and vector-camera measurements. A simple PI controller uses the estimated states to regulate yaw rate. Numerical simulations incorporating representative disturbance and measurement noise levels are used to evaluate closed-loop control performance and MEKF behavior under flight-like conditions. Experimental tests on the Taurus gondola validate the pivot-only approach, demonstrating stable high-rate tracking under realistic hardware constraints. The close agreement between simulation and experiment indicates that the simplified rigid-body model captures the dominant dynamics relevant for controller design and integrated estimation-and-control development.

Figures (6)

• Figure 1: a) CAD model of the Taurus gondola with cross-sectional view of the instrument. b) A cross-sectional view of the pivot and universal joint assembly, with Parker K178200-8Y1-CE frameless servo motor in purple. c) Simulated normalized sky coverage of Taurus in equatorial coordinates for a late-March launch and one month of nightly observations, with the orange band indicating the Galactic plane and gray regions corresponding to unobserved areas Adler2024May2024.
• Figure 2: Representative free-body diagram of the empty Taurus gondola with reference frames and external torque at the pivot (left), and simulated free-response dynamics from an initial $2^\circ$ tilt from the vertical axis with $\boldsymbol{\omega}_0 = [-0.5,\ \ 0.5,\ -10.0]^{\mathsf{T}} \ ^\circ/\mathrm{s}$ (right).
• Figure 3: One realization of simulated yaw-rate tracking (top) and corresponding control torque (bottom) for low-noise case.
• Figure 4: Attitude and bias estimation errors for the MEKF simulation with low-noise parameters.
• Figure 5: Experimental setup of the suspended Taurus gondola in the StarSpec Technologies facilities (left), and representative low-pass–filtered gyroscope angular-rate measurements illustrating free-response motion following an initial impulse (right).