Walking control method for automatic working vehicle

• US 5,083,629 A
• Filed: 03/12/1990
• Issued: 01/28/1992
• Est. Priority Date: 03/12/1990
• Status: Expired due to Fees

• Current Assignee: Industrial Technology Research Institute
• Original Assignee: Industrial Technology Research Institute
• Inventors: Chang, Chih-Li
• Primary Examiner(s): Kashnikow, Andres
• Assistant Examiner(s): Culbreth, Eric
• Application Number:
  US07/492,096
• Time in Patent Office: 687 Days
• Field of Search: 180/167, 180/168, 180/169, 180/612, 318/587, 56/10.2
• US Class Current: 180/168
• CPC Class Codes: A01D 2101/00 Lawn-mowers
• CPC Class Codes: A01D 34/008 for automated or remotely controlled operation
• CPC Class Codes: G05D 1/0265 using buried wires
• 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

Abstract

An automatic working machine which moves forward and turns back with a pre-determined shifted displacement to perform a task in a back and forth manner. The machine comprises sensors for detecting the boundaries of a defined area. The machine moves forward until the sensors detect a boundary or until a specific distance has been traveled, then the machine turns and proceeds forward in the opposite direction. The machine continues to perform in the specific back and forth motion until the task is completed.

Claims

1. An automatic working machine capable of moving in a back and forth manner with reference to guide lines defining a finite area, said machine comprising:

a machine body having front, rear, left and right sides;

two independent driving wheels and at least a caster wheel for supporting and allowing movement of said machine body, one of said independent driving wheels being mounted on said left side and the other one of said independent driving wheels being mounted on said right side, each of said independent driving wheels being capable of rotating at continuously varying speeds in at least one of a forward and reverse direction to drive said machine body to move straight and to turn;

guide line sensors mounted on said front of side to sense a position of lateral guide lines and to determine a moving direction of said machine body, said guide line sensors including left nd right sensors mounted on said left and right sides, respectively, of said machine body for sensing said guide line respectively and for enabling said wheel driver unit to determine an angle between a forward direction of said machine body and said guide line so as to control said machine to turn back;

a two wheel driver unit for driving said two driving wheels to move said machine body, said two wheel driver unit comprising means for controlling said machine body by setting said two independent driving wheels at different speeds to turn back said machine body in accordance with the following conditions;

(1) said machine body stops moving straight when said two guide line sensors sense the position of said guide line, the moving direction of said machine body and the direction perpendicular to said guide line forming an angle θ

, said angle θ

is defined by the formula;

space="preserve" listing-type="equation">θ

=+tan.sup.-1 (d/L), for -π

/2<

θ

<

π

/2

wherein a distance d is a difference between the distances traveled by said sensors in said moving direction of said machine body and a distance L is a mounting distance between said sensors and if a direction of the sensor that laterally senses said guide line is the same as a direction of shifted displacement of said machine body then θ

is positive, otherwise θ

is negative; and

(2) said two driving wheels move at different speeds, turning said machine body, and one of said two wheels moves around a radius ##EQU4## for a given distance "X", while the other one of said two wheels moves around a radius W+S for a given distance "Y", and after said machine body turns back so that said front of said machine body is perpendicular to said guide line, and a geometric center of said machine body shifts a predetermined displacement S thereof, and said machine body moves forward continuously, and if a distance between said two driving wheels is W, the distances "X" and "Y" can be obtained by;

space="preserve" listing-type="equation">X=|((±

π

+θ

)/2) (W-S)|

space="preserve" listing-type="equation">Y=|((±

π

+θ

)/2) (W-S)|

in which θ

being the angle in step (1), and if said machine body turns counter-clockwise, said π

is prefixed with "-";

otherwise, said π

is prefixed with "+"; and

two odometers providing feedback from said driving wheels to said two wheel driving unit for measuring rpm and mileage of said two driving wheels, the movement of said machine body including straight and turning movement, said straight movement being generally perpendicular to said guide line, and said turning movement varying the speed of said two independent driving wheels to reverse a direction of said machine body and shifting said machine body said pre-determined displacement.

2. An automatic working machine as claimed in claim 1, further comprising means for controlling said machine body to move straightly forward wherein said wheel driver unit counts a mileage of said left and right driving wheels respectively and minimizes the difference of said mileage to zero.

3. An automatic working machine as claimed in claim 2, where said wheel driver unit generates a motion instruction, whereby said machine body turns back after moving a present distance straightly forward so as to have said machine body turn reversely and shift a pre-determined displacement S;

and said two driving wheels move at different speeds respectively so as to have said machine body turn, i.e., one of said driving wheels moves a distance "X" around a radius, ##EQU5## while the other wheel moving a distance "Y" around a radius ##EQU6## said distance "X" and "Y" are obtained by;

space="preserve" listing-type="equation">X=±

π

/2 |W-S|

space="preserve" listing-type="equation">Y=±

π

/2 (W+S).

4. An automatic working machine capable of moving in a back and forth manner with reference to guide lines defining a finite area, said machine comprising:

a machine body having front, rear, left and right sides;

two independent driving wheels and at least a caster wheel for supporting and allowing movement of said machine body, one of said independent driving wheels being mounted on said left side and the other one of said independent driving wheels being mounted on said right side of said machine body, each of said independent driving wheels being capable of rotating at continuously varying speeds in at least one of a forward and reverse direction to drive said machine body to move straight and to turn;

guide line sensors mounted on said front side to sense a position of lateral guide lines and to determine a moving direction of said machine body, said guide line sensors including left and right sensors mounted on said left and right sides, respectively, of said machine body for sensing said guide line respectively and for enabling said wheel driver unit to determine an angle between a forward direction of said machine body and said guide line so as to control said machine to turn back;

a two wheel driver unit for driving said two driving wheels to move said machine body, said two wheel driver unit further comprising means for controlling said machine to turn backwards in accordance with the following conditions;

(1) after said machine moves straight forward for said two guide line sensors to detect said guide line, the following situations occur;

when said two guide line sensors are located at the same side of said lateral guide line, and have detected signals of the same strength, said driver unit drives said two independent driving wheels to move at different speeds turning said machine body backwards;

then a signal strength detected by said two guide line sensors is different for each sensor and said signal strength detected becomes equal again when said machine body has turned reversely and shifted a pre-determined displacement S; and

(2) when said two guide line sensors detect two signals respectively different in strength, said driver unit drives said two independent driving wheels to move at different speeds turning said machine body backwards, and one of said two driving wheels turns around a radius ##EQU7## W being a distance between said two driving wheels, until a signal strength detected by said two guide line sensors becomes equal at each sensor, wherein the direction of said machine body is perpendicular to said guide line, and said machine body is shifted a predetermined displacement S; and

two odometers providing feedback from said driving wheels to said two wheel driving unit for measuring rpm and mileage of said two driving wheels, the movement of said machine body including straight and turning movement, said straight movement being generally perpendicular to said guide line, and said turning movement varying the speed of said two independent driving wheels to reverse a direction of said machine body and shifting said machine body said pre-determined displacement.