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Masayoshi Tomizuka - One of the best experts on this subject based on the ideXlab platform.

  • a nonlinear feedback controller for aerial self righting by a tailed robot
    International Conference on Robotics and Automation, 2013
    Co-Authors: Evan Changsiu, Thomas Libby, Matthew Brown, Robert J Full, Masayoshi Tomizuka
    Abstract:

    In this work, we propose a control scheme for attitude control of a falling, two link active tailed robot with only two degrees of freedom of actuation. We derive a simplified expression for the robot's Angular momentum and invert this expression to solve for the shape velocities that drive the body's Angular momentum to a desired value. By choosing a body Angular Velocity Vector parallel to the axis of error rotation, the controller steers the robot towards its desired orientation. The proposed scheme is accomplished through feedback laws as opposed to feedforward trajectory generation, is fairly robust to model uncertainties, and is simple enough to implement on a miniature microcontroller. We verify our approach by implementing the controller on a small (175 g) robot platform, enabling rapid maneuvers approaching the spectacular capability of animals.

Sanjay P. Bhat - One of the best experts on this subject based on the ideXlab platform.

  • Time-Optimal Attitude Reorientation at Constant Angular Velocity Magnitude with Bounded Angular Acceleration
    Proceedings of the 45th IEEE Conference on Decision and Control, 2006
    Co-Authors: Mrityunjay Modgalya, Sanjay P. Bhat
    Abstract:

    This paper considers the problem of steering the orientation of an inertially symmetric rigid body of unit moment of inertia from an initial attitude and nonzero Angular Velocity to a specified terminal attitude in minimum time under an upper limit on the magnitude of Angular acceleration with the magnitude of the Angular Velocity constrained to remain constant. Optimal control theory is used to show that singular optimal arcs are uniform eigenaxis rotations in which the body rotates at a uniform rate about a body-fixed axis, while nonsingular arcs are coning motions in which the body Angular Velocity Vector rotates at a uniform rate about a body-fixed axis. Symmetries of the problem are exploited to further show that every optimal trajectory consists of at most one coning motion followed either by one uniform eigenaxis rotation or several coning motions of equal duration

R.k. Mehra - One of the best experts on this subject based on the ideXlab platform.

  • Spacecraft attitude tracking in the presence of input magnitude constraints
    Proceedings of the 2000 American Control Conference. ACC (IEEE Cat. No.00CH36334), 2000
    Co-Authors: P.o. Arambel, V. Manikonda, R.k. Mehra
    Abstract:

    We introduce a control strategy for tracking any feasible attitude trajectory in the presence of input magnitude constraints. To achieve asymptotic tracking without violating the constraints, the control strategy uses a combination of an exponentially convergent nonlinear controller, a "polhode" controller that exploits the geometry of the reduced dynamics to steer the Angular Velocity Vector and a time-scaling approach for reference trajectory redesign.

Evan Changsiu - One of the best experts on this subject based on the ideXlab platform.

  • a nonlinear feedback controller for aerial self righting by a tailed robot
    International Conference on Robotics and Automation, 2013
    Co-Authors: Evan Changsiu, Thomas Libby, Matthew Brown, Robert J Full, Masayoshi Tomizuka
    Abstract:

    In this work, we propose a control scheme for attitude control of a falling, two link active tailed robot with only two degrees of freedom of actuation. We derive a simplified expression for the robot's Angular momentum and invert this expression to solve for the shape velocities that drive the body's Angular momentum to a desired value. By choosing a body Angular Velocity Vector parallel to the axis of error rotation, the controller steers the robot towards its desired orientation. The proposed scheme is accomplished through feedback laws as opposed to feedforward trajectory generation, is fairly robust to model uncertainties, and is simple enough to implement on a miniature microcontroller. We verify our approach by implementing the controller on a small (175 g) robot platform, enabling rapid maneuvers approaching the spectacular capability of animals.

Rick Salmon - One of the best experts on this subject based on the ideXlab platform.

  • Shallow water equations with a complete Coriolis force and topography
    Physics of Fluids, 2005
    Co-Authors: Paul J. Dellar, Rick Salmon
    Abstract:

    This paper derives a set of two-dimensional equations describing a thin inviscid fluid layer flowing over topography in a frame rotating about an arbitrary axis. These equations retain various terms involving the locally horizontal components of the Angular Velocity Vector that are discarded in the usual shallow water equations. The obliquely rotating shallow water equations are derived both by averaging the three-dimensional equations and from an averaged Lagrangian describing columnar motion using Hamilton’s principle. They share the same conservation properties as the usual shallow water equations, for the same energy and modified forms of the momentum and potential vorticity. They may also be expressed in noncanonical Hamiltonian form using the usual shallow water Hamiltonian and Poisson bracket. The conserved potential vorticity takes the standard shallow water form, but with the vertical component of the rotation Vector replaced by the component locally normal to the surface midway between the upper...