Development of a compact solar array drive assembly based on ultrasonic motor for deep space micro-nano satellites

With the diversification and multifunctionality of space missions, micro-nano satellites need to carry more payloads in deep space orbits with harsh lighting conditions. Traditional built-in batteries and fixed deployable solar wings offer limited energy, making it difficult to meet these demands. Although solar wing drive mechanisms powered by stepper motors and harmonic reducers improve power output, their large size, weight, and complexity render them unsuitable for micro-nano satellites. This paper presents a solar array drive assembly driven by an ultrasonic motor, designed for micro-nano satellites operating in the halo orbit at the Lagrange L2 point of the Earth-Moon system. This design addresses the need for miniaturization and lightweight construction while enhancing energy supply. Key components, including the yaw axis pointing mechanism, solar panel assembly, angular displacement detection, energy transmission system, and ultrasonic motor, are optimized for size and weight reduction. To identify the optimal energy-saving drive method, a dynamic model of the SADA system is established, and a novel low-power driving method for the ultrasonic motor-driven solar wing is proposed. A prototype with a volume of less than 0.5U and a mass under 0.2 kg was fabricated. Experimental results show that the output torque of the ultrasonic motor exceeds 0.0581 N m, with the number of driving signal cycles n positively correlated with the total rotation angle θ of the solar wing. When n = 1000 and the interval time Tm = 1.35 h, the mechanism achieves its lowest energy consumption cost, allowing the solar wing to operate at 12.1° per day, saving over 23.8 % of energy compared to continuous drive methods.