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Ivancevic_Applied-Diff-Geom

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228 <strong>Applied</strong> <strong>Diff</strong>erential <strong>Geom</strong>etry: A Modern Introductionwhere x i , y i is the position of vehicle i and θ i is its orientation, or heading.The associated Lie algebra is se(2), with X i ∈ se(2) represented as⎡ ⎤0 −ω i v iX i = ⎣ ω i 0 0 ⎦ ,0 0 0where v i and ω i represent the translational (linear) and rotational (angular)velocities, respectively.Now, to determine dynamics of the relative configuration of two vehicles,we perform a change (transformation) of coordinates, to place the identityelement of the group SE(2) on vehicle 1. If g rel ∈ SE(2) denotes therelative configuration of vehicle 2 with respect to vehicle 1, theng 2 = g 1 g rel =⇒ g rel = g −11 g 2.<strong>Diff</strong>erentiation with respect to time yields the dynamics of the relativeconfiguration:which expands into:ġ rel = g rel X 2 − X 1 g rel ,ẋ rel = −v 1 + v 2 cos θ rel + ω 1 y rel ,ẏ rel = v 2 sin θ rel − ω 1 x rel ,˙θ rel = ω 2 − ω 1 .3.8.5.2 Two–Vehicles Conflict Resolution ManoeuvresNext, we seek control strategies for each vehicle, which are safe under (possible)uncertainty in the actions of neighbouring vehicle. For this, we expandthe dynamics of two vehicles (3.59),and write it in the matrix form asġ 1 = g 1 X 1 , ġ 2 = g 2 X 2 ,ġ = gX, (3.60)withg =[ ] [ ]g1 0X1 0, X = ,0 g 2 0 X 2

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