Browsing Department of Mathematics and Statistics: Dr. Andrew D. Lewis by Author "Lewis, Andrew D."
Now showing items 2133 of 33

Lifting distributions to tangent and jet bundles
Lewis, Andrew D. (1998)We provide two natural ways to lift a distribution from a manifold to its tangent bundle, and show that they agree if and only if the original distribution is integrable. The case when the manifold is the total space ... 
The linearisation of a simple mechanical control system
Bullo, Francesco; Lewis, Andrew D. (2002)A geometric interpretation is given for the linearisation of a mechanical control system with a kinetic minus potential energy Lagrangian. 
Loworder controllability and kinematic reductions for affine connection control systems
Bullo, Francesco; Lewis, Andrew D. (2002)Controllability and kinematic modeling notions are investigated for a class of mechanical control systems. First, loworder controllability results are given for a class of mechanical control systems. Second, a ... 
Nonholonomic mechanics and locomotion: the snakeboard example
Lewis, Andrew D.; Ostrowski, James P.; Burdick, Joel W.; Murray, Richard M. (IEEE, 1994)Analysis and simulations are performed for a simplified model of a commercially available variant on the skateboard, known as the Snakeboard.1 Although the model exhibits basic gait patterns seen in a large number of ... 
On the homogeneity of the affine connection model for mechanical control systems
Bullo, Francesco; Lewis, Andrew D. (IEEE, 2000)This work presents a review of a number of control results for mechanical systems. The key technical results derive mainly from the homogeneity properties of affine connection models for a large class of mechanical systems. ... 
Optimal control for a simplified hovercraft model
Coombs, A. Theo; Lewis, Andrew D. (2000)Timeoptimal and forceoptimal extremals are investigated for a planar rigid body with a single variable direction thruster. A complete and explicit characterisation of the singular extremals is possible for this problem. 
Reduction, linearization, and stability of relative equilibria for mechanical systems on Riemannian manifolds
Bullo, Francesco; Lewis, Andrew D. (2004)Consider a Riemannian manifold equipped with an infinitesimal isometry. For this setup, a unified treatment is provided, solely in the language of Riemannian geometry, of techniques in reduction, linearization, and stability ... 
Rigid body mechanics in Galilean spacetimes
bhand, Ajit; Lewis, Andrew D. (2004)An observerindependent formulation of rigid body dynamics is provided in the general setting of a Galilean spacetime. The equations governing the motion of a rigid body undergoing a rigid motion in a Galilean spacetime ... 
Simple mechanical control systems with constraints
Lewis, Andrew D. (IEEE, 2000)We apply some recently developed control theoretic techniques to the analysis of a class of mechanical systems with constraints. Certain simple aspects of the theory of affine connections play an important part in our ... 
Towards F=ma in a general setting for Lagrangian mechanics
Lewis, Andrew D. (1998)By using a suitably general definition of a force, one may geometrically cast the EulerLagrange equations in a ``force balance'' form. The key ingredient in such a construction is the EulerLagrange 2force which is a ... 
Variational principles for constrained systems: theory and experiment
Lewis, Andrew D.; Murray, Richard M. (1994)In this paper we present two methods, the nonholonomic method and the vakonomic method, for deriving equations of motion for a mechanical system with constraints. The resulting equations are compared. Results are also ... 
Vectorvalued quadratic forms in control theory
Bullo, Francesco; Cortes, Jorge; Lewis, Andrew D.; Martinez, Sonia (2002) 
What is the characteristic polynomial of a signal flow graph?
Lewis, Andrew D. (2002)