Maneuvering Robotic Vehicles

• US 20080183332A1
• Filed: 08/21/2007
• Published: 07/31/2008
• Est. Priority Date: 10/06/2006
• Status: Active Grant

• Current Assignee: Flir Detection, Inc. (Teledyne Technologies Incorporated)
• Original Assignee: iRobot Corporation
• Inventors: Bassett, Michael, Ohm, Timothy R.
• Granted Patent: US 8,644,991 B2
• Time in Patent Office: Days
• US Class Current: 700/250
• CPC Class Codes: B25J 5/005 mounted on endless tracks or belts
• CPC Class Codes: B62D 55/075 Tracked vehicles for ascending or descending stairs, steep slopes or vertical surfacesmagnetic or pneumatic ground-engaging parts B62D55/265; chairs or multi-track cycles specially adapted for invalids A61G5/00
• CPC Class Codes: G05D 1/0246 using a video camera in combination with image processing means
• CPC Class Codes: Y10S 901/01 Mobile robot

Abstract

Configurations are provided for vehicular robots or other vehicles to provide shifting of their centers of gravity for enhanced obstacle navigation. A robot chassis with pivotable driven flippers has a pivotable neck and sensor head mounted toward the front of the chassis. The neck is pivoted forward to shift he vehicle combined center of gravity (combined CG) forward for various climbing and navigation tasks. The flippers may also be selectively moved to reposition the center of gravity. Various weight distributions allow different CG shifting capabilities.

Claims

1. A robot capable of addressing various obstacles, comprising:

a chassis supporting a skid steered drive and having a leading end, a trailing end, and a chassis center of gravity (chassis CG) therebetween;

a set of driven flippers, each flipper having a pivot end, a distal end, and a flipper center of gravity (flipper CG) therebetween, each flipper being pivotable about a first pivot axis common with a drive axis near the leading end of the chassis;

a neck having a pivot end, a distal end, and a neck center of gravity (neck CG) therebetween, the neck pivotable about a second pivot axis substantially at the leading end of the chassis; and

a sensor head at the distal end of the neck, the head having a pivot end, a distal end, and a head center of gravity (head CG) therebetween, the head pivotable with respect to the neck about a third pivot axis at the distal end of the neck,

the chassis, flippers, neck and head;

(i) having a combined center of gravity (combined CG) disposed in a fore-aft sense between the distal and pivot ends of the flippers when the flippers are in a stowed position with their distal ends between the leading and trailing ends of the chassis, and

(ii) being movable between a first position and a second position to overcome an obstacle.

2. The robot of claim 1, wherein the first position is a stair ascending position in which the head, neck, and flipper CGs are each foreward of the leading end of the chassis such that the combined CG is forward of the chassis CG, and the second position is a stair descending position in which the head and neck CGs are disposed rearward of the leading end and the combined CG, such that the combined CG is rearward of the chassis CG.

3. The robot of claim 1 configured for climbing stairs having a pitch and step span, and wherein:

the chassis includes tracks defining a rearmost main track ground contact point;

each flipper includes a track defining a foremost flipper ground contact point;

the first position is a stable stair ascending position in which the head, neck, and flipper CGs are positioned to shift a vertical projection of the overall CG to at least one step span in front of the rearmost main track ground contact point and at least one step span behind the foremost flipper track ground contact point; and

the second position is an unstable stair ascending position in which the head, neck, and flipper CGs are positioned to shift a vertical projection of the overall CG to outside the stable range.

4. The robot of claim 1, wherein the first position is a crevasse approach position in which the head and neck CGs are aft of the leading end and aft of the combined CG, shifting the combined CG toward the trailing end, and the second position is a crevasse traversing position in which the head, neck, and flipper CGs are each fore of the leading end of the robot, shifting the combined CG toward the leading end.

5. The robot of claim 1, wherein the neck is adapted to carry payloads.

6. The robot of claim 1, wherein the flippers house at least part of a robot energy storage device and have a density higher than an average density of the robot.

7. The robot of claim 1, wherein the neck comprises at least one payload carrying fixture.

8. The robot of claim 1, further comprising a payload deck configured to support a removable cargo;

and a linkage connecting the payload deck to the chassis, the linkage having a first end rotatably connected to the chassis at a first pivot, and a second end rotatably connected to the deck at a second pivot.

9. The robot of claim 1, wherein the flippers are operable to pivot about a front wheel drive axis of the chassis.

10. The robot of claim 1, wherein the sensor head comprises about 15 percent of a total weight of the robot.

11. The robot of claim 1, wherein the neck comprises about 5 percent of a total weight of the robot.

12. The robot of claim 1, wherein the set of flippers is constructed to have a lower density than that of the skid steered drive.

13. The robot of claim 1, further comprising a rear set of flippers.

14. A method of controlling a robot to climb stairs having a first pitch and a first step span, wherein the robot comprises:

a chassis supporting a skid steered drive and having a leading end, a trailing end, and a chassis center of gravity (chassis CG) therebetween;

a set of driven flippers, each flipper having a pivot end, a distal end, and a flipper center of gravity (flipper CG) therebetween, each flipper being pivotable about a first pivot axis common with a drive axis near the leading end of the chassis;

a neck having a pivot end, a distal end, and a neck center of gravity (neck CG) therebetween, the neck pivotable about a second pivot axis substantially at the leading end of the chassis; and

a sensor head at the distal end of the neck, the head having a pivot end, a distal end, and a head center of gravity (head CG) therebetween, the head pivotable with respect to the neck about a third pivot axis at the distal end of the neck,

the chassis, flippers, neck and head;

(i) having a combined center of gravity (combined CG) disposed in a fore-aft sense between the distal and pivot ends of the flippers when the flippers are in a stowed position with their distal ends between the leading and trailing ends of the chassis, and

(ii) being movable between a first position and a second position to overcome an obstacle;

the method comprising directing the robot to;

approach the stairs;

raise flippers to an angle of at least about 30 degrees;

mount a lowermost stair to a first position where the chassis is oriented at approximately the first pitch;

adjust flipper orientation to approximately match the first pitch; and

adjust the position of the overall gravitation center of the robot (robot CG) by moving the neck forward into a stair ascending position.

15. The method of claim 14, wherein the robot has a furthest rear main track ground contact and a front-most front ground contact;

further comprising moving the neck and the head between a stair ascending position in which a vertical projection of the robot CG is located in a stable range at least one step span in front of the furthest rear main track ground contact and at least one step span behind the front most front track ground contact, and at least one alternate position in which the vertical projection of the robot CG is outside of the stable range.

16. A method of controlling a robot to overcome an obstacle, the method comprising directing the robot to perform the following tasks:

approach the obstacle;

raise flippers to an angle to mount the obstacle;

mount the obstacle to a first position where a robot chassis is oriented approximately at the first pitch;

adjust the flippers to shift a robot center of gravity at least laterally toward the obstacle; and

adjust a robot center of gravity (robot CG) by moving a neck forward into an obstacle mounting position.

17. The method of claim 16, wherein the adjusting the robot CG moves the robot CG downward.

18. The method of claim 16, wherein the robot comprises an articulated neck including a sensor head.

19. The method of claim 16, wherein the flippers house at least part of a robot energy storage device and have a density higher than an average density of the robot.

20. The method of claim 16, wherein the robot comprises an articulated neck further including payload-carrying fixtures.