Trajectory Tracking under Input Constraints

George J. Pappas, Graduate Student
Datta N. Godbole, Postdoctoral Researcher
John Lygeros, Postdoctoral Researcher

(Professor S. Shankar Sastry)

This work is motivated by the successful application of feedback linearization techniques to flight control problems. If the aircraft encounters severe disturbances, the actuators might saturate requiring on-line replanning of the reference trajectory.

In [1], we analyzed the effect of input saturation on feedback linearization and in designing controllers for stabilization and tracking. We calculate the regions of attraction of the controllers based on feedback linearization and characterize the space of feasible trajectories.

During trajectory tracking, demanding reference trajectories may result in actuator saturation. In [2], an algorithm is proposed where input saturation may be avoided by reparameterizing the reference trajectory on a slower time scale.

[1]

George J. Pappas, John Lygeros and Datta N. Godbole "Stabilization and Tracking of Feedback Linearizable Systems under Input Constraints", In proceedings of the 34th Conference in Decision and Control, New Orleans, December 1995.

[2]

George J. Pappas "Avoiding saturation by trajectory reparameterization", In proceedings of the 35th Conference in Decision and Control, Kobe, Japan, December 1996.