Abhishek Kumar, N. Viswanatha, M. V. Ramakrishna, and N. C. Bhat
ABSTRACT: This mechanism, also referred as Dual Gimbal Antenna (DGA) mechanism, is essentially a two axis rotary drive actuator mechanism which rotates an antenna about two orthogonal axes. The mechanism drives the antenna onboard a satellite to track the desired ground station in real time as the satellite is maneuvered. The need to slew the DGA during imagery collection which requires satellite jitter to be < 3 x 10e-4 deg./sec. has led to challenging requirements for the mechanism design. The mechanism mainly consists of mechanical housing, bearing assembly, brushless DC torque motor, multi-speed Resolver, cable twist capsule assembly and non-contact type RF Rotary joint for RF transmission. A Shape Memory Alloy (SMA) based Pin-puller is also developed for locking the drive actuators during launch and release of the same in orbit. The mechanism has been designed, qualified, flown and successfully operating onboard Cartosat-2 satellite. This paper gives the overall description, design and test results of the mechanism.
KEYWORDS: Gimbal, Resolver, Pin-puller, Flexi-print cable, Shape Memory Alloy
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