Development and Testing of the Flight Control System for a Tethered Wing

Feasibility Investigation of Attitude Control with Shape Memory Alloy Actuator on a Tethered Wing

“…A research team at the Toyota Research Institute of North America (TRINA) is investigating the feasibility of a high altitude aerial platform called "Mothership" [1]. This visionary air vehicle, essentially a large-scale kite made of an advanced inflatable structure, can offer unparalleled endurance and station keeping capabilities [2][3][4][5] that will make it suitable for missions such as large-scale airborne wind energy (AWE) harvesting [2], real-time atmospheric data acquisition and broadcasting, high-speed communication relays and disaster relief (Figure 1). The platform may serve as an incubator of various new technologies, encompassing novel actuators, sensors and lightweight structures.…”

“…Though they minimize drag by eliminating sudden flow separation along the airfoil camber, these hinge-line-free configurations require additional airfoil structures embedded in the wing section, which is difficult to achieve in an inflatable structure. Instead, we successfully installed servo motors onto the fabric envelope of a small-scale inflatable kite and demonstrated fly-by-wire control for stability augmentation and cross wind flight [3,4], utilizing concepts inspired by bird feathers [9]. However, mounting a rigid actuator becomes increasingly challenging as the kite size and required control power grow.…”

“…Such attributes are often computed in normalized metrics as shown in Figure 2, which allows a fair comparison independent of the application scale. [3,4] is compared with other actuators. The servo specs are from Pololu Robotics and Electronics [17].…”

“…The work density in the figure is defined as the ratio of the work done by the actuator and the actuator mass. Figure 2 also includes a high-frequency RC servo that we utilized to deflect control surfaces for a kite in previous research [3,4]. According to Figure 2, the piezoelectric actuator, dielectric elastomer actuator (DEA) and shape memory alloy (SMA) actuator appear to be good candidates to replace the RC servo.…”