Real-Time minimization of tracking error for aircraft systems
In many cases when an aircraft/spacecraft vehicle encounters a failure (such as a jammed control or loss of a part), there are still enough redundant actuation mechanisms to safely maneuver the vehicle. However, most pilots/autonomous systems are unable to adapt to the altered configuration and learn to control the damaged aircraft in the very short time available for safe operation. Fortunately, the flight computer may have the necessary information as well as bandwidth available to learn the new dynamics and determine mechanisms to control the vehicle quickly. The flight computer needs an intelligent controller that flies the vehicle with the baseline controller during normal conditions, and adapts the design when the vehicle suffers damage. Using information about the vehicle from all the available sensors, the system determines whether the vehicle is damaged. Direct adaptive control (DAC) looks directly at the errors, and updates the control law accordingly. This technology looks not just at the tracking error, but rather its characteristics over time to determine whether the controller needs to be adapted or left alone. This is typically fast and meets the timing considerations for aircraft/spacecraft system implementation.
• Complementary Adaptive/ Baseline Controllers
• Baseline Controller for Nominal Performance
• Adaptive Controller for Off Nominal Performance
• Retrofit possible to any existing control design
• Commercial/military aircraft
• Manned/unmanned land and space vehicles
• Lunar/planetary landers/ orbiters
• Robotic rovers
• Autonomous machines
This technology presents a novel stable discrete-time adaptive law for flight control in a DAC framework. Where errors are not present, the original control design has been tuned for optimal performance. Adaptive control works towards achieving nominal performance whenever the design has modeling uncertainties/errors or when the vehicle suffers substantial flight configuration change. The baseline controller uses dynamic inversion with proportional-integral augmentation. On-line adaptation of this control law is achieved by providing a parameterized augmentation signal to a dynamic inversion block. The parameters of this augmentation signal are updated to achieve the nominal desired error dynamics. Normal aircraft dynamics is modeled, using an original description in which a controller responds to a tracking error to drive the component to a normal reference value according to an asymptote. If the system senses that (1) at least one aircraft component is experiencing an excursion and (2) the return of this component value toward its reference value is not proceeding according to the expected controller characteristics then the neural network (NN) modeling of aircraft operation may be changed. If (1) above is satisfied but the error is returning toward its reference value according to expected controller characteristics, then the NN will continue to perform according to an original description.
This technology has been patented (U.S. Patent 8,285,659). Reference: ARC-16235-1.
Licensing and Partnering Opportunities
NASA’s Technology Transfer Program seeks to transfer this technology out of NASA’s space program to benefit U.S. industry. NASA invites companies to inquire about licensing possibilities for this technology for commercial applications.
For More Information
If you would like more information about this technology, please contact:
Technology Partnerships Division
NASA Ames Research Center