Airborne wind energy systems—tethered rigid wings that generate power during controlled flight—have long struggled with complex flight control requirements. Researchers have now demonstrated a simpler control approach that addresses a major barrier to commercialization: managing stable circular flight during the power-generation phase of operation.
The breakthrough lies in a novel feedback architecture that tracks roll angle relative to a reference frame that moves with the aircraft, effectively reducing what would normally be a multi-degree-of-freedom control problem into a single-degree-of-freedom challenge. This simplification allows the system to work reliably using only proportional-integral regulators—standard control components already familiar to power plant operators and engineers.
Unlike prior control designs that require operators to pre-program exact flight paths, this system maintains stability through a more flexible approach to navigation. In its basic form, the controller uses only aileron movements and requires no pitot-tube airspeed measurement, though adding additional control surfaces and sensors improves power generation efficiency.
Testing conducted on a six-degree-of-freedom simulation model—incorporating flexible tether dynamics, realistic aerodynamics, and variable wind conditions—confirmed the approach works reliably. The research team then developed three extensions to the core control law: first, an angle-of-attack stabilization feature that increases power output during reel-out; second, an automatic radius adjustment system that synchronizes multiple kites in farm configurations while maintaining safe separation distances; and third, a capability for figure-of-eight flight patterns.
The proportional-integral architecture's simplicity makes implementation straightforward, positioning it as an ideal baseline system for benchmarking more advanced control strategies. For the airborne wind energy sector, this represents meaningful progress toward economically viable multi-unit installations. By reducing control complexity without sacrificing performance or safety, the approach brings commercial-scale airborne wind systems closer to reality.
