Francesco Sansone

2D Close-Range Navigation Sensor for Miniature Cooperative Spacecraft

This paper presents the 2D close-range navigation sensor for cooperative spacecraft developed in the framework of the experiment ARCADE. The sensor exploits an infrared LED transmitter mounted on the target, and two photodiode receivers mounted on the chaser. Laboratory tests were performed to assess the sensor performance and range of application. The accuracies of estimates were, on average, 1.9 mm for distance and 1.0 deg for yaw angle, in ranges of [0.20, 0.42] m and [-40, 40] deg, respectively.

Design of an innovative Dielectric Elastomer actuator for space applications

The capability of Dielectric Elastomers to show large deformations under high voltage loads has been deeply investigated to develop a number of actuators concepts. From a space systems point of view, the advantages introduced by this class of smart materials are considerable and include high conversion efficiency, distributed actuation, self-sensing capability, light weight and low cost. This paper focuses on the design of a solid-state actuator capable of high positioning resolution. The use of Electroactive Polymers makes this device interesting for space mechanisms applications, such as antenna and sensor pointing, solar array orientation, attitude control, adaptive structures and robotic manipulators. In particular, such actuation suffers neither wear, nor fatigue issues and shows highly damped vibrations, thus requiring no maintenance and transferring low disturbance to the surrounding structures. The main weakness of this actuator is the relatively low force/torque values available. The proposed geometry allows two rotational degrees of freedom, and simulations are performed to measure the expected instant angular deflection at zero load and the stall torque of the actuator under a given high voltage load. Several geometric parameters are varied and their influence on the device behaviour is studied. Simplified relations are extrapolated from the numerical results and represent useful predicting tools for design purposes. Beside the expected static performances, the dynamic behaviour of the device is also assessed and the input/output transfer function is estimated. Finally, a prototype design for laboratory tests is presented; the experimental activity aims to validate the preliminary results obtained by numerical analysis.