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Ivancevic_Applied-Diff-Geom

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<strong>Applied</strong> Bundle <strong>Geom</strong>etry 577autonomous equations˙q i = ∂H 0∂p iṗ i = F i − ∂H 0∂q i+ ∂R∂p i, (i = 1, . . . , N) (4.68)+ ∂R∂q i , (4.69)q i (0) = q i 0, p i (0) = p 0 i , (4.70)including contravariant equation (4.68) – the velocity vector–field, and covariantequation (4.69) – the force 1−form, together with initial joint anglesq i 0 and momenta p 0 i . Here the physical Hamiltonian function H 0 : T ∗ M →R represents the total biodynamical energy function, in local canonical coordinatesq i , p i ∈ U p on T ∗ M given byH 0 (q, p) = 1 2 gij p i p j + V (q),where g ij = g ij (q, m) denotes the contravariant material metric tensor.Now, the control Hamiltonian function H γ : T ∗ M → R of FC is in localcanonical coordinates on T ∗ M defined by [Nijmeijer and van der Schaft(1990)]H γ (q, p, u) = H 0 (q, p) − q i u i , (i = 1, . . . , N) (4.71)where u i = u i (t, q, p) are feedback–control 1−forms, representing the spinalFC–level u−corrections to the covariant torques F i = F i (t, q, p).Using δ−Hamiltonian biodynamical system (4.68–4.70) and the controlHamiltonian function (4.71), control γ δ −Hamiltonian FC–system can bedefined as˙q i = ∂H γ(q, p, u) ∂R(q, p)+ ,∂p i ∂p iṗ i = F i − ∂H γ(q, p, u)∂q i +∂R(q, p)∂q i ,o i = − ∂H γ(q, p, u)∂u i, (i = 1, . . . , N)q i (0) = q i 0, p i (0) = p 0 i ,where o i = o i (t) represent FC natural outputs which can be different fromcommonly used joint angles.If nominal reference outputs o i R = oi R (t) are known, the simple PDstiffness–servo [Whitney (1987)] could be formulated, via error function

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