TRAJECTORY PLANNING METHOD, TRAJECTORY PLANNING SYSTEM AND TRAJECTORY PLANNING AND CONTROL SYSTEM

• US 20120277907A1
• Filed: 04/25/2012
• Published: 11/01/2012
• Est. Priority Date: 04/28/2011
• Status: Active Grant

• Current Assignee: Honda Motor Co., Ltd. (Honda Motor Company), Waseda University (Waseda University Educational Association)
• Original Assignee: Honda Motor Co., Ltd. (Honda Motor Company), Waseda University (Waseda University Educational Association)
• Inventors: KIM, Chyon Hae, SUGANO, Shigeki, YAMAZAKI, Shota
• Granted Patent: US 8,825,207 B2
• Time in Patent Office: Days
• US Class Current: 700/245
• CPC Class Codes: B25J 9/1664 characterised by motion, path, trajectory planning
• CPC Class Codes: G05B 2219/40448 Preprocess nodes with arm configurations, c-space and planning by connecting nodes
• CPC Class Codes: G05B 2219/40465 Criteria is lowest cost function, minimum work path

Abstract

A trajectory planning method according to the present invention is one for obtaining a trajectory for controlling a state of an object toward a goal state by a trajectory planning system. The method includes the steps of dividing, by a cell generating section for dividing a state space of the object into cells, the state space into cells in such a way that approximation error due to discretization is minimized for a predetermined number of cells; generating, by a search tree generating section, a search tree which corresponds to state transition of the object in such a way that each cell does not contain more than one of nodes of branches of the search tree; and determining, by a trajectory generating section, a path from the current state to the goal state of the object using the search tree.

Claims

1. A trajectory planning method for obtaining a trajectory for controlling a state of an object toward a goal state by a trajectory planning system, the method comprising the steps of:

dividing, by a cell generating section for dividing a state space of the object into cells, the state space into cells in such a way that approximation error due to discretization is minimized for a predetermined number of cells;

generating, by a search tree generating section, a search tree which corresponds to state transition of the object in such a way that each cell does not contain more than one of nodes of branches of the search tree, the nodes corresponding to states of the object; and

determining, by a trajectory generating section, a path from the current state to the goal state of the object using the search tree.

2. A trajectory planning method according to claim 1, wherein in the step of dividing the phase space into cells, an approximation error of a cell is represented as an average of a distance between a state to which any point in the cell transfers when an input is given and a state to which the center of the cell transfers when the input is given and the approximation error due to discretization is minimized by minimizing a sum of approximation errors of the cells in the phase space.

3. A trajectory planning method according to claim 1 or 2, wherein the step of dividing the phase space into cells includes a step of dividing the phase space into uniform basic cells, a step of dividing all the basic cells in such a direction as minimizes the approximation error of the cell, and a step of dividing and merging cells repeatedly to reduce a sum of approximation errors of the cells.

4. A trajectory planning system for obtaining a trajectory for controlling a state of an object toward a goal state, comprising:

a cell generating section for dividing a state space of the object into cells in such a way that approximation error due to discretization is minimized;

a search tree generating section for generating a search tree which corresponds to state transition of the object in such a way that each cell does not contain more than one of nodes of branches of the search tree, the nodes corresponding to states of the object; and

a trajectory generating section for determining a path from the current state to the goal state of the object using the search tree.

5. A trajectory planning and control system comprising the trajectory planning system according to claim 4 and a trajectory control section for realizing a trajectory determined by the trajectory planning system.