Machine configuration and method for steering a vehicle away from a wall

• US 4,986,378 A
• Filed: 03/06/1989
• Issued: 01/22/1991
• Est. Priority Date: 03/06/1989
• Status: Expired due to Term

• Current Assignee: Tennant Company
• Original Assignee: Tennant Company
• Inventors: Kasper, Joseph G.
• Primary Examiner(s): Marmor, Charles A.
• Assistant Examiner(s): Johnson, Brian L.
• Application Number:
  US07/319,355
• Time in Patent Office: 687 Days
• Field of Search: 180/168, 180/6.5, 180/6.66, 180/216, 180/167, 180/6.48, 180/6.64, 180/65.1, 364/424.02
• US Class Current: 180/6.48
• CPC Class Codes: A47L 11/4061 Steering means; Means for avoiding obstacles; Details related to the place where the driver is accommodated
• CPC Class Codes: B62D 1/24 not vehicle-mounted
• CPC Class Codes: B62D 11/02 by differentially driving ground-engaging elements on opposite vehicle sides

Abstract

A machine configuration which permits readily maneuvering a vehicle away from a wall or line of objects that the vehicle has been traveling close to, or closely following the walls around an inside corner. The vehicle has a frame carrying two rear drive wheels and one or more front caster wheels. The drive wheels are individually driven by separate motors. The drive wheels are inset from the sides of the machine so that turning maneuvers can be made adjacent a wall without the wheels contacting the wall. The rear frame or structure of the machine is disposed within an envelope defined such that turning maneuvers adjacent a wall unit will not bring the rear structure into contact with the wall. With the steering geometry and frame construction set up in this manner, the vehicle can be turned away from the wall by operating the drive motors at differential rates, and no part of the vehicle will touch the wall. The vehicle can also follow closely along an inside corner of two walls.

Claims

1. In a vehicle of the type having a frame defining a longitudinal axis and including first and second side members connected by front and rear members, first and second drive wheels mounted on the frame near the rear member, the rotational axes of the first and second drive wheels being fixed in perpendicular relation to said longitudinal axis, at least one forward wheel mounted on the frame near the front member, first and second drive means individually driving the first and second drive wheels respectively, an improved method of maneuvering the vehicle away from a wall without hitting the wall when the vehicle is initially traveling parallel to the wall and as close as possible to the wall, comprising the steps of:

(a) locating the first and second drive wheels such that each has an inset line at least as long as the long radius of the drive wheel from the center of which the inset line is measured;

(b) disposing the rear member of the frame within an envelope defined by a first arc described by swinging a radius equal to the inset line of the first drive wheel outwardly and rearwardly about a vertical axis through the center of said first drive wheel, by a second arc described by swinging a radius equal to the inset line of the second drive wheel outwardly and rearwardly about a vertical axis through the center of said second drive wheel, and by a rear vertical plane tangent to the two arcs; and

(c) turning the vehicle away from the wall about a fixed pivot point by operating the first and second drive means at differential rates for the duration of the turn.

2. The method of claim 1 further characterized in that the drive means of the drive wheel initially nearest the wall is operated at a higher rate than the other drive means.

3. The method of claim 1 further characterized in that the drive means of the drive wheel initially farthest from the wall is stopped while the other drive means continues to operate.

4. The method of claim 1 further characterized in that the drive means of the drive wheel initially farthest from the wall is operated in reverse and the other drive means continues to operate in a forward direction.

5. The method of claim 1 further characterized in that the drive means of the drive wheel initially farthest from the wall is operated in reverse and the other drive means is stopped.

6. The method of claim 1 further characterized in that the first and second drive means are operated at constant rates for the duration of the turn.

7. The method of claim 1 wherein the wall is characterized by a line of objects.

8. In an automated, unmanned floor maintenance machine of the type having a frame defining a longitudinal axis and including first and second side members connected by front and rear members, first and second drive wheels mounted on the frame near the rear member, the rotational axes of the first and second drive wheels being fixed in perpendicular relation to said longitudinal axis, at least one forward wheel mounted on the frame near the front member, first and second drive means individually driving the first and second drive wheels respectively, an improved method of maneuvering the machine away from a wall without hitting the wall when the machine is initially traveling parallel to the wall and as close as possible to the wall, comprising the steps of:

(a) locating the first and second drive wheels such that each has an inset line at least as long as the long radius of the drive wheel from the center of which the inset line is measured;

(b) disposing the rear member of the frame within an envelope defined by a first arc described by swinging a radius equal to the inset line of the first drive wheel outwardly and rearwardly about a vertical axis through the center of said first drive wheel, by a second arc described by swinging a radius equal to the inset line of the second drive wheel outwardly and rearwardly about a vertical axis through the center of said second drive wheel, and by a rear vertical plane tangent to the two arcs; and

(c) turning the machine away from the wall about a fixed pivot point by operating the first and second drive means at differential rates for the duration of the turn.

9. The method of claim 8 further characterized in that the drive means of the drive wheel initially nearest the wall is operated at a higher rate than the other drive means.

10. The method of claim 8 further characterized in that the drive means of the drive wheel initially farthest from the wall is stopped while the other drive means continues to operate.

11. The method of claim 8 further characterized in that the drive means of the drive wheel initially farthest from the wall is operated in reverse and the other drive means continues to operate in a forward direction.

12. The method of claim 8 further characterized in that the drive means of the drive wheel initially farthest from the wall is operated in reverse and the other drive means is stopped.

13. The method of claim 8 further characterized in that the first and second drive means are operated at constant rates for the duration of the turn.

14. The method of claim 8 wherein the wall is characterized by a line of objects.

15. In an automated, unmanned floor maintenance machine of the type having a frame defining a longitudinal axis and including first and second side members connected by front and rear members, first and second drive wheels mounted on the frame near the rear member, the rotational axes of the first and second drive wheels being fixed in perpendicular relation to said longitudinal axis, at least one forward wheel mounted on the frame near the front member, first and second drive means individually driving the first and second drive wheels respectively, and means for performing floor maintenance, an improved method of maneuvering the machine without a portion of the frame hitting a wall so as to maintain a floor in a corner of a walled area having a first wall and a second wall intersecting with the first wall, comprising the steps of:

(a) locating the first and second drive wheels such that each has an inset line at least as long as the long radius of the drive wheel from the center of which the inset line is measured;

(b) disposing the rear member of the frame within an envelope defined by a first arc described by swinging a radius equal to the inset line of the first drive wheel outwardly and rearwardly about a vertical axis through the center of said first drive wheel, by a second arc described by swinging a radius equal to the inset line of the second drive wheel outwardly and rearwardly about a vertical axis through the center of said second drive wheel, and by a rear vertical plane tangent to the two arcs;

(c) operating the machine parallel and adjacent to the first wall and moving it toward the intersection of the first and second walls until the foremost portion of the machine in the direction of movement is adjacent to the second wall;

(d) thereafter turning the machine away from the first wall by rotating the drive wheel farthest from the first wall in reverse while preventing rotation of the drive wheel nearest to the first wall; and

(e) thereafter maneuvering the machine to position it adjacent to the first and second walls, with its longitudinal axis parallel to the second wall, the machine being headed away from the intersection of the first and second walls.

16. A vehicle capable of maneuvering away from a wall without hitting the wall when the vehicle is initially traveling parallel to the wall and as close as possible to the wall, comprising:

a frame defining a longitudinal axis and including first and second side members connected by front and rear members;

first and second drive wheels mounted on the frame near the rear member, the rotational axes of the first and second drive wheels being fixed in perpendicular relation to said longitudinal axis, the first and second drive wheels being positioned such that each has an inset line at least as long as the long radius of the drive wheel from the center of which the inset line is measured;

at least one forward caster wheel mounted on the frame near the front member;

first and second drive means individually driving the first and second drive wheels respectively;

the rear member of the frame being disposed within an envelope defined by a first arc described by swinging a radius equal to the inset line of the first drive wheel outwardly and rearwardly about a vertical axis through the center of said first drive wheel, by a second arc described by swinging a radius equal to the inset line of the second drive wheel outwardly and rearwardly about a vertical axis through the center of said second drive wheel, and by a rear vertical plane tangent to the two arcs.

17. An automated, unmanned floor maintenance machine capable of maneuvering away from a wall without hitting the wall when the vehicle is initially traveling parallel to the wall and as close as possible to the wall, comprising:

a frame defining a longitudinal axis and including first and second side members connected by front and rear members;

first and second drive wheels mounted on the frame near the rear member, the rotational axes of the first and second drive wheels being fixed in perpendicular relation to said longitudinal axis, the first and second drive wheels being positioned such that each has an inset line at least as long as the long radius of the drive wheel from the center of which the inset line is measured;

at least one forward caster wheel mounted on the frame near the front member;

first and second drive means individually driving the first and second drive wheels respectively;

means for performing floor maintenance mounted on the frame;

the rear member of the frame being disposed within an envelope defined by a first arc described by swinging a radius equal to the inset line of the first drive wheel outwardly and rearwardly about a vertical axis through the center of said first drive wheel, by a second arc described by swinging a radius equal to the inset line of the second drive wheel outwardly and rearwardly about a vertical axis through the center of said second drive wheel, and by a rear vertical plane tangent to the two arcs.