Automatic guide method for vehicles

• US 5,672,947 A
• Filed: 09/15/1995
• Issued: 09/30/1997
• Est. Priority Date: 09/15/1995
• Status: Expired due to Term

• Current Assignee: Yazaki Industrial Chemical Co., Ltd. (Yazaki Corporation)
• Original Assignee: Yazaki Industrial Chemical Co., Ltd. (Yazaki Corporation)
• Inventors: Otake, Hiromi, Hisada, Yukio, Ike, Tadashi, Sugiyama, Motohiro
• Primary Examiner(s): Masih, Karen
• Application Number:
  US08/529,094
• Time in Patent Office: 746 Days
• Field of Search: 318/587, 318/580, 364/443, 364/447, 364/424.01
• US Class Current: 318/587
• CPC Class Codes: G05D 1/0263 using magnetic strips

Abstract

The automatic guide method for vehicles relates to an automatic guide method for the operation of unmanned vehicles which, guided along guide paths preset on the floor in factories and warehouses, etc., carry and handle various loads in a fully automated fashion, and more particularly to an automatic guide method which has a course-search function and function to prevent straying such that a vehicle which is positioned at the start of an operation with its magnetic sensor off the guide path within certain limits or which strays off course abruptly for some reason during ordinary operation, is restored to the guide path by searching and finding the magnetic tape.

Claims

1. An automatic guide method for a vehicle having:

a driving wheel,

a magnetic sensor that detects a magnetic field generated by a guide path which is made of magnetic tape and which is placed on a floor along a running course of said vehicle,

driving means, operatively connected with said driving wheel, for moving said vehicle, and

a steering means controlled by a control device that processes signals detected by said sensor, for steering said vehicle, comprising the steps of;

turning said sensor, on commencement of vehicle operation, right and left and searching for the guide path with said vehicle at a standstill;

turning said vehicle, if the guide path cannot be found, constantly in a first direction while moving said vehicle at a predetermined low speed to search for the guide path for a first predetermined time, and, if the guide path is still not found,

turning said vehicle while moving at the predetermined low speed, constantly in a second direction opposite to the first direction for a second predetermined time which is essentially twice as long as the first predetermined time;

accelerating said vehicle, if the guide path is found, along the guide path to a predetermined normal speed in order to resume a normal operation; and

halting said vehicle if the guide path is not found during the first and second preset times.

2. An automatic guide method for a vehicle having:

a driving wheel,

a magnetic sensor that detects a magnetic field generated by a guide path which is made of magnetic tape and which is placed on a floor along a running course of said vehicle,

driving means operatively connected with said driving wheel for moving said vehicle, and

steering means controlled by a control device that processes signals detected by said magnetic sensor, comprising the steps of;

reducing the speed of said vehicle, if said vehicle strays off course and deviates from the guide path during operation, to a predetermined low speed;

determining a direction in which said vehicle has deviated from the guide path;

turning said steering means in a direction opposite to the direction of the deviation;

searching for the guide path for a preset period of time, and if said vehicle is restored to the guide path, accelerating said vehicle to a normal speed in order to resume normal operation; and

terminating the operation of said vehicle if the guide path cannot be located within said preset time.

3. An automatic guide method for a vehicle which includes:

a driving and steering unit which has;

a driving means for driving a driving wheel of said vehicle, and

a steering means for steering said driving wheel, and

a trolley having a chassis which has wheels at the four corners thereof,

said driving means being controlled by a control device that processes signals from a sensor that detects the magnetic field generated by a guide path formed with magnetic tape, said driving and steering unit being attached to the under surface of the chassis, comprising the step of;

controlling said steering means, at the start of operation, to turn said magnetic sensor right and left in unison with the driving wheel when searching for the guide path.

4. An automatic guide method for a vehicle which includes:

a chassis forming part of said vehicle,

two driving wheels, one provided on either side of said chassis,

a sensor, provided at the front portion of said chassis, for detecting a magnetic field generated by a magnetic guide tape placed on a surface along which said vehicle travels,

two driving means one provided for each of said driving wheels, said driving means being controlled by control devices that process signals detected by said sensor, and

steering means that differentially drives said two driving wheels through said driving means that are controlled by said control device, comprising the step of;

turning said chassis right and left, at the start of operation, by controlling said steering means to turn said magnetic sensors right and left by differentially driving said two driving wheels.

5. A method of automatically guiding a vehicle comprising the steps of:

using a sensor to detect a predetermined guide which is laid along a running course of the vehicle;

locating the predetermined guide by;

moving the sensor back and forth from left to right while the vehicle has no forward motion;

turning the vehicle, if the guide is not found by moving the sensor back and forth from left to right, constantly in a first direction while moving the vehicle at a predetermined low speed to search for the guide for a first predetermined time, and, if the guide is still not found,

turning the vehicle, while moving at the predetermined low speed, constantly in a second direction opposite to the first direction for a second predetermined time which is essentially twice as long as the first predetermined time; and

halting the vehicle if the guide path is not found during the first and second preset times.

6. A method of automatically guiding a vehicle comprising the steps of:

using a sensor to sense a predetermined guide structure which is laid along a path the vehicle is required to traverse;

reducing vehicle speed to a predetermined low speed, if the vehicle strays off course and deviates from the predetermined guide structure by an amount wherein the sensor can no longer detect the predetermined guide structure;

determining a direction in which the vehicle deviated from the guide path;

turning the vehicle in a direction opposite to the direction of the deviation;

executing a search for a preset period of time; and

stopping the vehicle if the guide path cannot be located within the preset time.

7. A method of controlling an automatic vehicle comprising the steps of:

controlling a vehicle by turning the vehicle, left and right while the vehicle is not moving forward, in a manner which moves a sensor, located at the front of the vehicle, left and right in search of a guide which marks a path the vehicle is to follow;

controlling the vehicle, in the event that the guide is not detected by the sensor, to move forward at a predetermined low speed while turning the vehicle constantly to one of left and right for a first predetermined time;

controlling the vehicle, in the event that the guide is still not detected by the sensor, to move forward at a predetermined low speed while turning the vehicle constantly to the other of left and right for a second predetermined time which is approximately twice as long as the first predetermined period of time; and

stopping the vehicle in the event that the guide is not detected by the sensor in either of the first and second predetermined periods of time.

8. A method of controlling an automatic vehicle which includes:

a chassis,

two driving wheels operatively mounted on said chassis,

a sensor disposed at a front portion of the chassis, said sensor detecting a guide provided along a path the vehicle travels, and

steering means for differentially driving the two driving wheels, comprising the step of;

turning the chassis, if said sensor does not detect the guide at the start of operation, back and forth from left to right with essentially no forward motion of the vehicle, by controlling the steering means to differentially drive the two driving wheels in a manner which sweeps the magnetic sensor right and left in search of the guide.

9. A method as set forth in claim 8, further comprising the steps of:

moving the vehicle forward at a predetermined low speed if the guide has not been detected by said sensor during the turning of the chassis left and right with no forward motion;

turning the vehicle continuously in one the left and right directions for a predetermined period of time, and, if the said sensor does not detect the guide within the predetermined time,

turning the vehicle continuously to the other of the left and right for a second predetermined time which is longer than the first predetermined period of time; and

stopping the vehicle if the guide is not found during the second predetermined period of time.