Autonomous mobile robot

• US 10,124,490 B2
• Filed: 08/31/2016
• Issued: 11/13/2018
• Est. Priority Date: 01/10/2014
• Status: Active Grant

• Current Assignee: iRobot Corporation
• Original Assignee: iRobot Corporation
• Inventors: Schnittman, Mark, Bushman, Thomas W.
• Primary Examiner(s): Tran, Dalena
• Application Number:
  US15/252,355
• Publication Number:
  US 20170080570A1
• Time in Patent Office: 804 Days
• Field of Search: 700245, 700250, 700253, 700258, 901 1, 901 46, 901 47, 701 23, 701 25, 701 28, 701532, 31856812, 31856816, 318584-586
• CPC Class Codes: B25J 9/1694 characterised by use of sensors other than normal servo-feedback from position, speed or acceleration sensors, perception control, multi-sensor controlled systems, sensor fusion
• CPC Class Codes: G05D 1/0227 using mechanical sensing means, e.g. for sensing treated area
• CPC Class Codes: G05D 1/027 comprising intertial navigation means, e.g. azimuth detector inertial navigation G01C21/16; inertial navigation combined with non-inertial navigation instruments G01C21/165
• 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
• CPC Class Codes: Y10S 901/01 Mobile robot
• CPC Class Codes: Y10S 901/46 Sensing device
• CPC Class Codes: Y10S 901/49 Protective device

Abstract

An autonomous mobile robot includes a robot body, a drive system, a sensor system, and a controller. The drive system supports the robot body and maneuvers the robot over a floor surface. The sensor system includes an inertial measurement unit for measuring a pose of the robot and issues a sensor signal including data having information regarding a pose of the robot. The controller communicates with the drive and sensor systems and executes a behavior system. The behavior system receives the sensor signal from the sensor system and executes a behavior. The behavior system executes an anti-stasis behavior in response to sensor signals indicating that the robot is constrained to evaluate a state of constraint. In addition, the behavior system executes an anti-tilt behavior in response to sensor signals indicating that the robot is tilted with respect to a direction of gravity to evaluate a state of tilt.

Claims

1. An autonomous mobile robot comprising:

a drive system configured to maneuver the robot over a floor surface;

a sensor system comprising wheel encoders and an inertial measurement unit configured to measure a pose of the robot, the sensor system configured to issue signals indicative of the pose of the robot; and

a controller in communication with the drive system and the sensor system,

wherein the controller is configured to control the drive system to execute an anti-stasis behavior in response to at least one signal from the sensor system indicating that the robot is constrained, and

wherein the controller is configured to control the drive system to execute an anti-tilt behavior in response to at least one signal from the inertial measurement unit of the sensor system indicating that the robot is tilted with respect to a direction of gravity.

2. The robot of claim 1, wherein the drive system is configured to evaluate a state of constraint by executing a first wiggle command having a first wiggle angle, the first wiggle command comprising drive commands to drive in alternating left and right drive directions angled with respect to each other by the first wiggle angle.

3. The robot of claim 2, wherein when the controller receives at least one signal from the inertial measurement unit or at least one of the wheel encoders indicating that the robot is not exhibiting wiggle drive motions as commanded, the robot is configured to execute a second wiggle command having a second wiggle angle greater than the first wiggle angle.

4. The robot of claim 3, wherein the controller is configured to issue an anti-stasis command to the drive system when signals of the inertial measurement unit and/or at least one of the wheel encoders are not within an allowable tolerance for indicating robot movement.

5. The robot of claim 1, wherein a state of constraint comprises the robot entering or being in a wedged position with respect to an object.

6. The robot of claim 5, wherein the at least one signal from the sensor system comprises:

a bump signal indicating contact of the robot with the object; and

a wheel drop signal indicating movement of a wheel of the drive system away from the robot body.

7. The robot of claim 1, wherein the anti-stasis behavior comprises execution of a drive command that backs the robot away from an impediment or turns the robot away from a side of the robot experiencing constraint.

8. The robot of claim 7, wherein the anti-stasis behavior further comprises execution of a drive command that drives the robot in an arcuate trajectory.

9. The robot of claim 1, wherein the controller is configured to control the drive system to execute the anti-tilt behavior when the robot is tilted with respect to the direction of gravity for at least a threshold period of time.

10. The robot of claim 9, wherein the anti-tilt behavior comprises execution of a reverse drive command when the robot is pitched up with respect to the direction of gravity and a forward drive direction, and comprises execution of a forward drive command when the robot is pitched down with respect to the direction of gravity and the forward drive direction.

11. The robot of claim 1, wherein the controller is configured to control the drive system to execute the anti-tilt behavior when the robot is tilted with respect to the direction of gravity at an angle greater than a threshold angle.

12. The robot of claim 11, wherein the anti-tilt behavior comprises execution of a reverse drive command when the robot is pitched up with respect to the direction of gravity and a forward drive direction, and comprises execution of a forward command when the robot is pitched down with respect to the direction of gravity and the forward drive direction.

13. The robot of claim 1, wherein the sensor system further comprises a plurality of mechanical switches disposed on a bottom surface of the robot forward of a driven wheel of the drive system, each of the mechanical switches configured to be activated when an obstacle contacts the mechanical switch.

14. The robot of claim 13, wherein the controller is configured to control the drive system to execute the anti-stasis behavior when the mechanical switches are activated.

15. The robot of claim 14, further comprising a cleaning system for cleaning or treating the floor surface, wherein the cleaning system comprises a driven roller brush and a side brush.

16. The robot of claim 15, wherein the controller is configured to control the drive system to execute an anti-ingestion behavior when the mechanical switches are activated and the sensor system detects motion, the anti-ingestion behavior comprising issuance of a cleaning stop command for stopping a cleaning behavior and issuance of a wiggle command having a wiggle angle, the wiggle command comprising drive commands to drive in alternating left and right drive directions angled with respect to each other by the wiggle angle.

17. The robot of claim 16, wherein the controller is configured to control the drive system to execute a wheel jam behavior when the controller receives a signal from the sensor system indicating that the wheels of the robot are stalling at a stalling rate less than a stalling threshold rate, the wheel jam behavior causing issuance of the wiggle command for releasing a stalled wheel of the robot.

18. The robot of claim 17, further comprising a driven roller brush extending parallel to a transverse axis X and configured to contact a floor surface, the driven roller brush being configured to rotate in a first direction about the X axis, wherein the anti-ingestion behavior comprises biasing of the roller brush to passively rotate in a second direction opposite the first direction.

19. An autonomous mobile robot, comprising:

a drive system that drives right and left drive wheels and is configured to maneuver the robot over a floor surface;

a sensor system comprising an inertial measurement unit configured to measure a pose of the robot; and

a controller in communication with the drive system and the sensor system,

wherein the controller controls the drive system to execute an anti-tilt behavior in response to at least one signal from the inertial measurement unit of the sensor system indicating that the robot is tilted with respect to a direction of gravity.

20. The robot of claim 19, wherein the anti-tilt behavior comprises execution of a reverse drive command when the robot is pitched up with respect to the direction of gravity and a forward drive direction, and comprises execution of a forward drive command when the robot is pitched down with respect to the direction of gravity and the forward drive direction.

21. The robot of claim 19, wherein the controller is configured to control the drive system to execute the anti-tilt behavior when the robot is tilted with respect to the direction of gravity at an angle greater than a threshold angle.

22. The robot of claim 19, wherein the sensor system further comprises a plurality of mechanical switches disposed on a bottom surface of the robot forward of driven wheels of the drive system, each of the mechanical switches configured to be activated when an obstacle contacts the mechanical switch.

23. The robot of claim 22, wherein the controller is configured to control the drive system to execute an anti-ingestion behavior when the mechanical switches are activated and the sensor system detects motion, the anti-ingestion behavior comprising issuance of a cleaning stop command for stopping a cleaning behavior and issuance of a wiggle command, the wiggle command comprising drive commands to drive in alternating left and right drive directions.

24. The robot of claim 23, further comprising a driven roller brush extending parallel to a transverse axis X and configured to contact a floor surface, the driven roller brush being configured to rotate in a first direction about the X axis, wherein the anti-ingestion behavior comprises biasing of the roller brush to passively rotate in a second direction opposite the first direction.