Robotic vehicle with deduced reckoning positioning system

• US 6,046,565 A
• Filed: 06/19/1998
• Issued: 04/04/2000
• Est. Priority Date: 06/19/1998
• Status: Expired due to Term

• Current Assignee: St Engineering Aethon Incorporated
• Original Assignee: Aethon, Inc.
• Inventors: Thorne, Henry F.
• Primary Examiner(s): Nappi, Robert E.
• Assistant Examiner(s): Duda, Rina I.
• Application Number:
  US09/100,910
• Time in Patent Office: 655 Days
• Field of Search: 318/568.11, 318/568.12, 318/568.14, 318/580, 318/587, 318/52, 901/1, 180/197, 701/2, 701/26, 701/23, 701/41, 701/82, 701/210, D12/134, D12/135, D21/578
• US Class Current: 318/587
• CPC Class Codes: B25J 5/007 mounted on wheels
• 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

A robotic vehicle includes two independent axially colinear wheels, wherein the wheels form the only contact with the floor when the robotic vehicle is at rest. A robot body is mounted between the wheels, and a ded-reckoning positioning system is mounted on the robot body. Each wheel includes a series of circumferentially spaced points forming the surface contact of said wheel with the floor. A graphical user interface is provided for manipulating the robotic vehicle. A robot attaching harness is on the robot body for coupling auxiliary equipment to the robotic vehicle. The ded-reckoning positioning system updates the relative position and orientation of the robotic vehicle through measurement of wheel rotation, and calculates an amount of slip for each wheel.

Claims

1. A robotic vehicle comprising:

two independent axially co-linear wheels, wherein said wheels form the only contact with the floor when said robotic vehicle is at rest;

a robot body mounted between said wheels wherein a center of mass of said robot body at rest is vertically aligned with said wheel axes; and

a positioning system mounted on said robot body.

2. The robotic vehicle of claim 1 wherein each said wheel includes a series of circumferentially spaced points forming the surface contact of said wheel with the floor.

3. The robotic vehicle of claim 2 wherein said points of each said wheel are spaced from each other between 0.05 and 0.2 times a diameter of said wheel and wherein a thickness of each said point is less than about 0.375 inches.

4. The robotic vehicle of claim 2 wherein said points of each said wheel are coated with a material having a relatively high coefficient of friction.

5. The robotic vehicle of claim 1 further including a robot attaching harness on said robot body for coupling auxiliary equipment to said robotic vehicle, said attaching harness attached to said robot body at a midpoint between said wheels.

6. The robotic vehicle of claim 5 wherein said attaching harness is rotatable about a vertical axis which intersects the axis of said wheels at a midpoint between said wheels.

7. The robotic vehicle of claim 1 wherein said positioning system is a ded-reckoning positioning system which includes means for measuring wheel rotation and automatically updates the relative position and orientation of the robotic vehicle through measurement of wheel rotation.

8. The robotic vehicle of claim 7 wherein said means for measuring wheel rotation includes and least one encoder for each said wheel.

9. The robotic vehicle of claim 7 wherein said ded-reckoning positioning system updates the position and orientation of said robotic vehicle to a new position (X2, Y2, A2) from an original position (X1, Y1, A1)according to the following:

space="preserve" listing-type="equation">A2=A1+((dWB-dWA)/L)

space="preserve" listing-type="equation">X2=X1+((dWA+dWB)*COS (A)/2)

space="preserve" listing-type="equation">Y2=Y1+((dWA+dWB)*SIN (A)/2);

wherein X and Y refer to a Cartesian position of said robotic vehicle in a reference plane, A is an angle of orientation of said robotic vehicle with respect to a Y axis, dWA and dWB are amounts of respective wheel travel, and L is an axle length between said pair of wheels.

10. The robotic vehicle of claim 7 wherein said ded-reckoning positioning system calculates an amount of slip for each said wheel.

11. The robotic vehicle of claim 10 further including an independent motor attached to said robot body, each said motor for driving one said wheel.

12. The robotic vehicle of claim 11 wherein said amount of slip for each said wheel is calculated as a function of velocity of said wheel, acceleration of said wheel, current applied to said wheel motor and voltage applied to said wheel motor.

13. The robotic vehicle of claim 11 wherein said amount of slip for each said wheel is calculated as a linear function of current applied to said wheel motor.

14. The robotic vehicle of claim 1 wherein said Positioning system is a ded-reckoning positioning system which includes means for calibrating an absolute position of said robotic vehicle relative to a fixed reference marker to eliminate accumulated error in a calculated position of said robotic vehicle.

15. The robotic vehicle of claim 14 wherein means for calibration is adapted to calibrate said position of said robotic vehicle relative to the fixed reference marker which includes two mutually perpendicular calibration surfaces.

16. The robotic vehicle of claim 1 further including a graphical user interface for manipulating said robotic vehicle.

17. The robotic vehicle of claim 16 wherein said graphical user interface includes a top view of a room containing said robotic vehicle and an icon of the respective position and orientation of said robotic vehicle within the room.

18. The robotic vehicle of claim 17 wherein a vector established from said icon in said graphical user interface is used to control torque applied to each respective wheel of said robotic vehicle.

19. A wheel for a robotic vehicle wherein said wheel includes a series of circumferentially spaced points forming the surface contact of said wheel with the floor, wherein the thickness of each said point is less than about 0.375 inches.

20. The wheel for a robotic vehicle of claim 19 wherein said points of each said wheel are coated with a material having a relatively high coefficient of friction, and said points of said wheel are spaced from each other between 0.05 and 0.2 times a diameter of said wheel.

23. The wheel for a robotic vehicle of claim 19 wherein a gap is positioned between adjacent points which defines an area at least 0.25 inches by 0.25 inches.

24. The wheel for a robotic vehicle of claim 19 wherein the outer 0.25 inches of the diameter of the wheel has a thickness of less than about 0.375 inches.

21. A robotic vehicle comprising:

at least two independent axially colinear wheels;

a robot body mounted between said wheels, wherein a center of mass of said robot body is aligned vertically below an axle line of both axles of said two wheels; and

a robot attaching harness on said robot body for coupling auxiliary equipment to said robotic vehicle, said attaching harness attached to said robot body at a midpoint between said wheels.

22. The robotic vehicle of claim 21 wherein said attaching harness is rotatable about a vertical axis which intersects the axis of said wheels at a midpoint between said wheels.

25. A ded-reckoning positioning system for a robotic vehicle, said ded-reckoning positioning system comprising a means for measuring robotic vehicle wheel rotation, wherein said ded-reckoning positioning system automatically updates the relative position and orientation of the robotic vehicle through measurement of wheel rotation, and wherein said ded-reckoning positioning system calculates an amount of slip for each wheel of the robotic vehicle, wherein said amount of slip for each wheel is calculated as a function of velocity of the wheel, acceleration of the wheel, current applied to the wheel motor and voltage applied to the wheel motor.

26. The ded-reckoning positioning system for a robotic vehicle of claim 25 wherein said amount of slip for each robotic wheel is calculated as a linear function of current applied to a wheel motor.

27. The ded-reckoning positioning system for a robotic vehicle of claim 25 wherein said ded-reckoning positioning system includes means for calibrating an absolute position of the robotic vehicle relative to a fixed reference marker to eliminate accumulated error in a calculated position of the robotic vehicle.

28. The ded-reckoning positioning system for a robotic vehicle of claim 27 wherein means for calibration is adapted to calibrate said position of the robotic vehicle relative to the fixed reference marker which includes two mutually perpendicular calibration surfaces.

29. A graphical user interface for manipulating a robotic vehicle, said graphical user interface comprising a top view of a room containing the robotic vehicle and an icon of the respective position and orientation of the robotic vehicle within the room, wherein a vector established from said icon in said graphical user interface is used to control each respective wheel of the robotic vehicle to move the robotic vehicle in the direction of said vector.