Design and Analysis of a 6-DoF Compliant Vibration Isolator for Small Satellite Optical Payloads Considering Ball-Joint Effects

Received: 16 January 2026 | Revised: 6 February 2026, 19 February 2026, 26 February 2026, and 28 February 2026 | Accepted: 2 March 2026 | Online: 6 June 2026

Corresponding author: Ngoc Pham Van Bach

Abstract

The performance of optical payloads on satellites is dependent on the mechanical stability of the satellite structure. Although spatial, spectral, temporal, and radiometric resolutions are commonly used to characterize image quality, these indicators do not adequately capture image degradation caused by micro-vibrations originating from satellite subsystems, such as driven motors, reaction wheels, control moment gyroscopes, cryo-coolers, and solar panel drive mechanisms, or structural resonances. In high-resolution optical payloads, low-frequency vibrations can induce image blur, pointing errors, and long-term structural fatigue, thereby reducing mission effectiveness. This study presents the design and analysis of a six-Degrees of Freedom (6-DoF) passive vibration isolation mechanism intended for optical payload stabilization of satellite platforms. The proposed device is based on a parallel compliant architecture derived from the Stewart-Gough platform with a specially shaped leg and ball joint. The kinematic behavior of the platform was first examined through Jacobian formulation and singularity analysis to ensure stable operation within the intended workspace. Based on this analysis, a compliant mechanism employing S-shaped flexible legs combined with spherical ball joints was developed to provide effective vibration attenuation while preserving high stiffness in non-motion directions. Dynamic simulations were conducted under harmonic base excitations with frequencies ranging from 5 to 25 Hz, representative of typical micro-vibration sources in satellite systems. The results demonstrate that the proposed isolator provides effective vibration attenuation in the low- and mid-frequency bands, with isolation efficiencies increasing from approximately 5% at 5 Hz to about 56% at 20 Hz. At the upper limit of the investigated frequency range (25 Hz), a marked reduction in isolation efficiency was observed, indicating a degradation of isolation performance near this frequency. Nevertheless, the isolator maintained positive isolation behavior throughout the investigated range without exhibiting amplification effects. Comparative studies with alternative leg geometries further demonstrated the superiority of the proposed configuration in terms of isolation efficiency and dynamic stability. These results indicate that the proposed 6-DOF passive compliant mechanism is well-designed for enhancing the image quality and structural integrity of optical payloads in high-resolution remote sensing satellites.