Method and apparatus for controlling automated guided vehicle

• US 5,002,145 A
• Filed: 01/26/1989
• Issued: 03/26/1991
• Est. Priority Date: 01/29/1988
• Status: Expired due to Fees

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Tsukagoshi, Tsuneo, Wakaumi, Hiroo
• Primary Examiner(s): Marmor, Charles A.
• Assistant Examiner(s): CAMBY, RICHARD M
• Application Number:
  US07/303,169
• Time in Patent Office: 789 Days
• Field of Search: 180/167, 180/168, 180/169, 340/935, 340/933, 340/994, 901/1, 901/46, 901/47, 364/513
• US Class Current: 180/168
• CPC Class Codes: B62D 1/28 non-mechanical , e.g. following a line or other known markers

Abstract

In a method of controlling travel of an automated guided vehicle, the automated guided vehicle is guided to travel along a guide marker arranged in a lattice form when the automated guided vehicle goes straight, and, when it turns, curve travel by autonomous control from a starting lattice point to a target lattice point.

Claims

1. A method of controlling travel of an automated guided vehicle, comprising the steps of:

guiding said automated guided vehicle along a guide marker arranged in a lattice form when said automated guided vehicle goes straight;

when said automated guided vehicle turns, causing it to perform an autonomous travel along a curved path from one lattice point to another lattice point;

providing, in said autonomous travel, necessary deviation angles to left and right wheels of said automated guided vehicle at the one lattice point;

monitoring numbers of rotations of said left and right wheels during the autonomous travel in order to measure a travel distance of said automated guided vehicle;

comparing the travel distance with a value corresponding to a length of the curved path; and

nullifying the deviation angles of said left and right wheels when the travel distance coincides with the value in order to cause said automated guided vehicle to go straight by a guiding step.

2. A method of controlling travel of an automated guided vehicle, comprising the steps of:

guiding said automated guided vehicle along a guide marker arranged in a lattice form when said automated guided vehicle goes straight;

when said automated vehicle turns, causing it to perform an autonomous travel along a curved path from one lattice point to another lattice point;

detecting an obstacle in front of said automated guided vehicle by first sensor means attached to said automated guided vehicle, the step of detecting the obstacle including the step of comparing a time difference T_X of obstacle detection signals obtained from two front sensors which are included in said first sensor means and having different detection distances with a reference value T_R and, when T_X is smaller than T_R, identifying the detected obstacle as an emergency obstacle and when T_X is equal to or larger than T_R, identifying the detected obstacle as an existing obstacle; and

causing said automated guided vehicle to perform a mode of travel comprising a combination of guide-controlled and autonomous travels while maintaining a distance to the obstacle by using second sensor means attached to said automated guided vehicle.

3. An apparatus for controlling travel of an automated guided vehicle which performs a guided travel along a guide marker formed in a lattice form and an autonomous travel on a curved path from one lattice point to another lattice point, comprising:

two front sensors attached to a front portion of said automated guided vehicle and having different detection distances; and

a controller, provided to said automated guided vehicle, for obtaining a time difference T_X between obstacle detection signals from said two front detectors, for comparing the time difference T_X with a prestored reference value T_R, for, when T_X <

T_R, recognizing the obstacle as an emergency obstacle, and when T_X ≧

T_R, recognizing the obstacle as an existing obstacle, and for supplying data corresponding to a travel mode constituted by a combination of the guided travel and the autonomous travel according to a detected case to a wheel drive system of said automated guided vehicle.

4. An apparatus according to claim 3, further comprising left and right sensors for detecting obstacles on left side and right side of said automated guided vehicle, respectively.