Path correction method for a self-contained unmanned vehicle

• US 4,939,650 A
• Filed: 06/14/1988
• Issued: 07/03/1990
• Est. Priority Date: 06/14/1988
• Status: Expired due to Fees

• Current Assignee: Shinko Electric Industries Company Limited (Fujitsu Limited)
• Original Assignee: Shinko Electric Industries Company Limited (Fujitsu Limited)
• Inventors: Nishikawa, Yuji
• Primary Examiner(s): Black, Thomas G.
• Application Number:
  US07/206,371
• Time in Patent Office: 749 Days
• Field of Search: 364/424.02, 364/424.01, 364/443, 364/449, 364/559, 180/167-169
• US Class Current: 701/26
• CPC Class Codes: G05D 1/0255 using acoustic signals, e.g. ultra-sonic singals sonar systems designed for anti-collision purposes G01S15/93
• CPC Class Codes: G05D 1/0272 comprising means for registering the travel distance, e.g. revolutions of wheels measuring distance traversed on the ground by vehicles, e.g. using odometers G01C22/00
• CPC Class Codes: G05D 1/0274 using mapping information stored in a memory device navigation using map-matching G01C21/30

Abstract

A method for controlling a robotic vehicle as the robotic is traversed from an origination node to a destination node is disclosed. An optimal nodal path is determined from the origination node to the destination node. A deviation distance is calculated from the actual location of the robotic vehicle to the optimal nodal path. This deviation distance is compared with the specified distance. If the deviation distance exceeds the specified distance, a determination is made as to whether correction of the travel path of the robotic vehicle by a combination of curves method would result in the robotic vehicle returning to the optimal path beyond a node to be traversed next. Correction of the travel path is effected by the combination of curves method if correction by such a method would result in the robotic vehicle returning to the optimal nodal path prior to the node to be traversed next. On the other hand, correction of the travel path is effected by a side-step movement method if correction of the travel path by the combination of curves method would result in the robotic vehicle returning to the optimal nodal path beyond the node to be traversed next.

Claims

1. A method for controlling a robotic vehicle as the robotic vehicle is traversed from an origination node to a destination node, said method comprising the steps of:

(a) determining an optimal nodal path from the origination node to the destination node, the optimal nodal path being defined by a plurality of nodes, each of the plurality nodes representing a target location at which the robotic vehicle is to be traversed;

(b) determining an actual location of the robotic vehicle as the robotic vehicle is traversed from node to node;

(c) determining a deviation distance of the robotic vehicle, the deviation distance being a distance from the actual location of the robotic vehicle to the optimal nodal path;

(d) comparing the deviation distance with a specified distance; and

, when the deviation distance exceeds the specified distance,

(e) determining whether correction of a travel path of the robotic vehicle by a combination of curves method would result in the robotic vehicle returning to the optimal nodal path beyond a node to be traversed next;

(f) correcting the travel path of the robotic vehicle by a combination of curves method if correction of the travel path by the combination of curves method would result in the robotic vehicle returning to the optimal nodal path prior to a node to be traversed next;

(g) correcting the travel path of the robotic vehicle by a side-step movement method if correction of the travel path by the combination of curves method would result in the robotic vehicle returning to the optimal nodal path beyond the node to be traversed next;

wherein the combination of curves method includes traversing the robotic vehicle in rectilinear and curvature motions to the optimal nodal path, and wherein the side-step movement method includes traversing the robotic vehicle directly to the optimal nodal path.

2. A method as recited in claim 1, wherein said step (e) comprises the step of:

determining a first distance from a first point on the optimal nodal path at which the robotic vehicle deviates from the optimal nodal path to the node to be traversed next;

determining a second distance from the first point on the optimal nodal path at which the robotic vehicle deviates from the optimal nodal path to a second point on the optimal nodal path at which the robotic vehicle would return to the optimal nodal path if the combination of curves method was used to correct the travel path;

comparing the first and second distances;

wherein step (f) is effected if the first distance is greater than the second distance, and wherein step (g) is effected if the second distance is greater than the first distance.

3. A method for controlling a robotic vehicle as the robotic vehicle is traversed from an origination node to a destination node, said method comprising the steps of:

(a) determining an optimal nodal path from the origination node to the destination node, the optimal nodal path being defined by a plurality of nodes, each of the plurality of nodes representing a target location at which the robotic vehicle is to be traversed;

(b) determining an actual location of the robotic vehicle as the robotic vehicle is traversed from node to node;

(c) determining a deviation distance of the robotic vehicle, the deviation distance being a distance from the actual location of the robotic vehicle to the optimal nodal path;

(d) comparing the deviation distance with a specified distance; and

, when the deviation distance exceeds the specified distance,

(e) determining whether correction of a travel path of the robotic vehicle by a combination of curves method would result in the robotic vehicle returning to the optimal nodal path beyond a node to be traversed next;

(f) correcting the travel path of the robotic vehicle by a combination of curves method if correction of the travel path by the combination of curves method would result in the robotic vehicle returning to the optimal nodal path prior to a node to be traversed next;

(g) correcting the travel path of the robotic vehicle by a side-step movement method of correction if the travel path by the combination of curves method would result in the robotic vehicle returning to the optimal nodal path beyond the node to be traversed next;

wherein the combination of curves method includes traversing the robotic vehicle along a first curve in a first curvature direction until one half of the specified distance extending from the optimal nodal path is traversed, and traversing the robotic along a second curve in a second curvature direction opposite the first curvature direction from a point at which the robotic vehicle deviates from the optimal nodal path by one half the specified distance to a point at which the robotic vehicle returns to the optimal nodal path, and

wherein the side-step movement method includes stopping the robotic vehicle and then traversing the robotic vehicle directly to the optimal nodal path.

4. A method as recited in claim 3, wherein said step (e) comprises the steps of:

determining a first distance from a first point on the optimal nodal path at which the robotic vehicle deviates from the optimal nodal path to the node to be traversed next;

determining a second distance from the first point on the optimal nodal path at which the robotic vehicle deviates from the optimal nodal path to a second point on the optimal nodal path at which the robotic vehicle would return to the optimal nodal path if the combination of curves method was used to correct the travel path;

comparing the first and second distances,

where step (f) is effected if the first distance is greater than the second distance, and wherein step (g) is effected if the second distance is greater than the first distance.