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Automated Guided Vehicle Optimal Control Problem. Preliminary Research. Reijer Idema. Automated Guided Vehicle Optimal Control Problem. Supervisors: prof.dr.ir. P. Wesseling dr.ir. Kees Vuik ir. Patrick H.F. Segeren dr.ir. Ren é Jager. FROG Navigation Systems. FROG Navigation Systems
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Automated Guided VehicleOptimal Control Problem Preliminary Research Reijer Idema
Automated Guided Vehicle Optimal Control Problem Supervisors: prof.dr.ir.P.Wesseling dr.ir.KeesVuik ir.Patrick H.F. Segeren dr.ir.René Jager
FROG Navigation Systems FROG Navigation Systems www.frog.nl • AGV : Automated Guided Vehicle • industrial transport • public transport • entertainment • FROG : Free Ranging On Grid • grid of magnets
Problem Formulation (Textual) Suppose an AGV has to perform an action in the world. Find the best control input for the AGV to achieve the action.
Example Problem 1/3 Vehicle model: • point mass • throttle on/off • instant steering • orientation = path direction Vehicle task: • hallway (2D) • collect at A • deliver at B
Example Problem 2/3 Internal state space: • throttle: • steering wheel: • collect/deliver:N/A External state space: • position: • orientation: • velocity: • collect/deliver: N/A
Example Problem 3/3 Task: • begin position/orientation • end position/orientation Internal Constraints: • [no jumping] • [no sharp corners] External Constraints: • keep clear of obstacles
Tools Path description: • NURBS curves Solver Algorithm: • Local search methods
NURBS Curves NURBS: Non-Uniform Rational B-Spline: • parametric curve: C(u) = (x(u),y(u)) • piecewise rational function
Knot Vector Properties Knot vector: U = {u0,…,um} • knot multiplicity k • non-periodic: u0 = … = up = a um-p = … = um = b consequence: C(u0)=P0, C(um)=Pn
Basis Function Properties Basis function: Ni,p(u;U) • depends only on degree p and knot vector U • local support property: • partition of unity • non-negativity • polynomial on each knot span • C on the interior of a knot span • Cp-k at a knot with multiplicity k
B-Spline Properties B-Spline: C(u;P,U) • piecewise polynomial • C on the interior of a knot span • Cp-k at a knot with multiplicity k • local modification scheme moving Pi modifies C(u) only on [ui,ui+p+1) • strong convex hull property
NURBS Properties NURBS: C(u;P,U,W) • piecewise rational • C on the interior of a knot span • Cp-k at a knot with multiplicity k • local modification scheme moving Pi or changing wi modifies C(u) only on [ui,ui+p+1) • strong convex hull property
Homogeneous Representation A rational curves of dimension d can be represented by a non-rational curve of dimension d+1 using homogeneous coordinates.
B-Spline Operations 1/2 • knot insertion and knot refinement • knot removal • degree elevation • degree reduction • point inversion and point projection • reparameterization • conversion to and from piecewise power basis form
B-Spline Operations 2/2 • control point and weight modification relatively easy calculations • high level shaping tools warping, flattening, bending and constraint based curve shaping • curve fitting interpolation and approximation
Research Planning 1/3 Task: • path from A to B Vehicle model: • point mass • 2D work area • orientation = path direction • disconnect velocity Extensions: • vehicle body • higher dimensions (crabbing, etc.)
Research Planning 2/3 Internal constraints: • general description • constraint preserving operations External constraints: • hull curve • collision free path
Research Planning 3/3 Cost and heuristics: • cost function time, energy consumption • heuristics straight, circular corner Solver algorithm: • highly constructive • local search
Q & A ?