Navigation system and process for guiding unmanned industrial trucks without guide wire

• US 5,219,036 A
• Filed: 07/22/1992
• Issued: 06/15/1993
• Est. Priority Date: 04/05/1989
• Status: Expired due to Fees

• Current Assignee: Wagner Fordertechnik GmbH
• Original Assignee: Wagner Fordertechnik GmbH
• Inventors: Sommer, Gerhard, Schwager, Jurgen, Dongus, Michael
• Primary Examiner(s): Camby, Richard M.
• Application Number:
  US07/918,666
• Time in Patent Office: 328 Days
• Field of Search: 180/167, 180/168, 180/169, 318/587, 318/586, 364/424, 364/425, 364/424.01, 364/424.02, 356/1, 356/4, 356/141, 356/152
• US Class Current: 180/168
• 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 1/0261 using magnetic plots

Abstract

A navigation system for guiding unmanned vehicles with any desired wheel configuration without guide wire for free movement on paths and along curves along a virtual reference path having at least one straight and/or curved section. Discrete elements are floor-installed which are in operative connection with a vehicle internal path control device via the vehicle'"'"'s internal sensory analysis system for correcting the course of the industrial truck. The discrete elements are arranged at spaced locations exclusively along the area of the reference path forming a linear formation chain as navigation reference points P. The distance between the reference points P are either regular or irregular and may be relatively great distances equal to a multiple of the wheel base of the vehicle. The on-board sensory analysis system exclusively determines the distances and measures the distance between the longitudinal axis of the industrial truck and the navigation reference point P.

Claims

1. A navigation method for a self-guiding vehicle, the method comprising the steps of:

providing a navigation reference point;

determining a reference path having said navigation reference point;

storing said reference path and a position of said navigation reference point in the self-guiding vehicle;

transforming said stored reference path into nominal control values S_nominal and α

_nominal ;

moving the self-guiding vehicle in response to said nominal control value S_nominal ;

setting a steering angle of the self-guiding vehicle in response to said nominal control value α

_nominal ;

measuring actual movement S_actual of the self-guiding vehicle

measuring an actual steering angle α

_actual of the self-guiding vehicle;

measuring a deviation between said navigation reference point and the self-guiding vehicle as the self-guiding passes said navigation reference point;

determining if the self-guiding vehicle is away from said reference path;

calculating a correction path to lead the self-guiding vehicle to said reference path if the self-guiding vehicle is away from said reference path, said measured actual movement, said measured actual steering angle and said measured deviation being used for said calculating of said correction path;

transforming said correction path into updated nominal control values S_nominal and α

_nominal ;

moving the self-guiding vehicle in response to said updated nominal control value S_nominal ;

setting a steering angle of the self-guiding vehicle in response to said updated nominal control value α

_nominal in order for the self-guiding to navigate.

2. A navigation method according to claim 1, further comprising the steps of:

providing another navigation reference point positioned in said reference path;

storing a position of said another navigation reference point in the self-guiding vehicle;

measuring another deviation between said another navigation reference point and the self-guiding vehicles as the self-guiding passes said another navigation reference point;

calculating an absolute regular position of the self-guiding vehicle from said measured deviation and said another measured deviation; and

said another measured deviation and said absolute angular position of the self-guiding vehicle for said calculating of said correction path.

3. A navigation method according to claim 1, wherein:

said measuring of said deviation is between a substantially center of said navigation reference point and a substantially longitudinal axis of the self-guiding vehicle.

4. A navigation method according to claim 1, further comprising the steps of:

providing an external computer;

transforming said reference path into space coordinates with said external computer; and

downloading said navigation reference point and said transformed reference path into the self-guiding vehicle.

5. A navigation method according to claim 1, further comprising the steps of:

p1 providing a plurality of navigation reference points positioned in said reference path;

storing positions of said plurality of navigation reference points in the self-guiding vehicle;

measuring a deviation between each of said plurality of navigation reference points and the self-guiding vehicle as the self-guiding passes each of said plurality of navigation reference points;

calculating an absolute angular position of the self-guiding vehicle at each of said plurality of navigation reference points, said calculating of said absolute angular position using said measured deviation of a present navigation reference point and a measured deviation of a previous navigation reference point; and

using said absolute angular position of the self-guiding vehicle, said measured deviation of said present navigation reference point and said measured deviation of said previous navigation reference point for said calculating of said correction path, and said correction leading to a subsequent navigation reference point.

6. A navigation method according to claim 5, further comprising the steps of:

spacing said plurality of navigation reference points at one of regular and/or irregular distances apart.

7. A navigation method according to claim 5, further comprising the steps of:

presetting at each of said plurality of navigation reference points a safety section S_max representing one of a time and/or distance within which a subsequent navigation reference point must be detected; and

stopping the self-guiding vehicle if said subsequent navigation reference point is not detected within said safety section S_max.

8. A navigation method according to claim 5, further comprising the steps of:

transforming said reference path and said position of said plurality of navigation reference points into a set of geometric data in a spatially fixed system of coordinates x, y;

providing additional feedback into a space control loop substantially simultaneously with said moving of the self-guiding vehicle in response to said nominal control value S_nominal and said setting of said steering angle of the self-guiding vehicle in response to said nominal control value α

_nominal, said providing of said additional feedback being performed by transforming said measured actual movement and said measured actual steering angle into space coordinates x, y and absolute angular position γ

, and controlling one of said movement and/or said steering angle in dependence upon said space coordinates; and

continuously repeating said calculating of said correction path and providing feedback during further travel of the self-guiding vehicle.

9. A navigation method according to claim 8, further comprising the steps of:

continuously calculating space coordinates x'"'"', y'"'"', γ

'"'"', of the self-guiding vehicle from said S_actual and α

_actual during said moving of the self-guiding vehicle from a present navigation reference point to a subsequent navigation reference point.