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Motion Planning. 154 slides. What is the motion planning problem? What is the fundamental question in motion planning problem? What is the basic problem formulation? Configuration Space. Formalism for Configuration Space. What is a Path? Extensions to the Basic Motion Planning Probem
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154 slides • What is the motion planning problem? • What is the fundamental question in motion planning problem? • What is the basic problem formulation? • Configuration Space. • Formalism for Configuration Space. • What is a Path? • Extensions to the Basic Motion Planning Probem • Examples of Applications of Motion Planning • Examples of Practical Algorithms: Bug 2. • Examples : Probabilistic Roadmaps.
Motion Planning for a Humanoid Robot with Many Degrees of Freedom in real world environment
Goal of Motion Planning • Compute motion strategies, e.g.: • geometric paths • time-parameterized trajectories • sequence of sensor-based motion commands • To achieve high-level goals,e.g.: • go to A without colliding with obstacles • assemble product P • build map of environment E • find object O
Fundamental Question Are two given points connected by a path? Valid region Forbidden region
E.g.: ▪Collision with obstacle ▪Lack of visibility of an object ▪Lack of stability Fundamental Question Are two given points connected by a path? Valid region Forbidden region
What is the formulation of the basic problem of path finding ?
Basic Problem of Path planning • Statement:Compute a collision-free path for a rigid or articulated object (the robot) among static obstacles • Inputs: • Geometry of robot and obstacles • Kinematics of robot (degrees of freedom) • Initial and goal robot configurations (placements) • Output: • Continuous sequence of collision-free robot configurations connecting the initial and goal configurations
Piano-mover problem Examples with Rigid Object Ladder problem
Compare! Valid region Forbidden region
Tool: Configuration Space • Problems: • Geometric complexity • Space dimensionality
Example of simple configuration space for a robot with 2DOF in planar space
In presence of obstacles, where the robot can actually move?
Robot that can translate and rotate in 2D space gives another dimension to the problem
C-obstacle in Three-Dimensional Space This is twisted
x Can we stay in 2D?
What is a Path? Path is a very general concept considered from the point of view of computational geometry, time and search
Configuration Space qn q=(q1,…,qn) q3 q1 q2 In real problems configuration space is highly dimensional
Definition of Robot Configuration • A robot configuration is a specification of the positions of all robot points relative to a fixed coordinate system • Usually a configuration is expressed as a “vector” of position/orientation parameters
Rigid Robot Example • 3-parameter representation: q = (x,y,q) • In a 3-D workspace q would be of the form (x,y,z,a,b,g) workspace robot reference direction q y reference point x Like you need six-dimensional space to describe the airplane in the air