demos/RigidBodyPlanningWithODESolverAndControls.py
00001 #!/usr/bin/env python
00002 
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00036 
00037 # Author: Mark Moll
00038 
00039 from math import sin, cos, tan
00040 from functools import partial
00041 try:
00042     from ompl import base as ob
00043     from ompl import control as oc
00044     from ompl import geometric as og
00045 except:
00046     # if the ompl module is not in the PYTHONPATH assume it is installed in a
00047     # subdirectory of the parent directory called "py-bindings."
00048     from os.path import abspath, dirname, join
00049     import sys
00050     sys.path.insert(0, join(dirname(dirname(abspath(__file__))),'py-bindings'))
00051     from ompl import base as ob
00052     from ompl import control as oc
00053     from ompl import geometric as og
00054 
00055 def kinematicCarODE(q, u, qdot):
00056     theta = q[2];
00057     carLength = 0.2;
00058     qdot[0] = u[0] * cos(theta)
00059     qdot[1] = u[0] * sin(theta)
00060     qdot[2] = u[0] * tan(u[1]) / carLength
00061 
00062 
00063 def isStateValid(spaceInformation, state):
00064     # perform collision checking or check if other constraints are
00065     # satisfied
00066     return spaceInformation.satisfiesBounds(state)
00067 
00068 def plan():
00069     # construct the state space we are planning in
00070     space = ob.SE2StateSpace()
00071 
00072     # set the bounds for the R^2 part of SE(2)
00073     bounds = ob.RealVectorBounds(2)
00074     bounds.setLow(-1)
00075     bounds.setHigh(1)
00076     space.setBounds(bounds)
00077 
00078     # create a control space
00079     cspace = oc.RealVectorControlSpace(space, 2)
00080 
00081     # set the bounds for the control space
00082     cbounds = ob.RealVectorBounds(2)
00083     cbounds.setLow(-.3)
00084     cbounds.setHigh(.3)
00085     cspace.setBounds(cbounds)
00086 
00087     # define a simple setup class
00088     ss = oc.SimpleSetup(cspace)
00089     validityChecker = ob.StateValidityCheckerFn(partial(isStateValid, ss.getSpaceInformation()))
00090     ss.setStateValidityChecker(validityChecker)
00091     ode = oc.ODE(kinematicCarODE)
00092     odeSolver = oc.ODEBasicSolver(ss.getSpaceInformation(), ode)
00093     propagator = oc.ODESolver.getStatePropagator(odeSolver)
00094     ss.setStatePropagator(propagator)
00095 
00096     # create a start state
00097     start = ob.State(space)
00098     start().setX(-0.5);
00099     start().setY(0.0);
00100     start().setYaw(0.0);
00101 
00102     # create a goal state
00103     goal = ob.State(space);
00104     goal().setX(0.0);
00105     goal().setY(0.5);
00106     goal().setYaw(0.0);
00107 
00108     # set the start and goal states
00109     ss.setStartAndGoalStates(start, goal, 0.05)
00110 
00111     # attempt to solve the problem
00112     solved = ss.solve(120.0)
00113 
00114     if solved:
00115         # print the path to screen
00116         print("Found solution:\n%s" % ss.getSolutionPath().asGeometric().printAsMatrix())
00117 
00118 if __name__ == "__main__":
00119     plan()
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