Obstacle following sensor scheme for a mobile robot
A robot obstacle detection system including a robot housing which navigates with respect to a surface and a sensor subsystem aimed at the surface for detecting the surface. The sensor subsystem includes an emitter which emits a signal having a field of emission and a photon detector having a field of view which intersects the field of emission at a region. The subsystem detects the presence of an object proximate the mobile robot and determines a value of a signal corresponding to the object. It compares the value to a predetermined value, moves the mobile robot in response to the comparison, and updates the predetermined value upon the occurrence of an event.
1. A robot comprising:
a drive system configured to maneuver the robot across a floor surface, the drive system comprising a first wheel and a second wheel;
cliff sensors housed in a forward portion of the robot, each cliff sensor aimed at the floor surface;
a vacuum inlet disposed on a bottom side of the robot;
a first side brush rotatably mounted in the forward portion of the robot, the first side brush configured to direct debris from the floor surface towards the vacuum inlet; and
a second side brush rotatably mounted in the forward portion of the robot, the second side brush configured to direct debris from the floor surface towards the vacuum inlet;
wherein the first side brush and the second side brush are each mounted at approximately equal distances from the vacuum inlet and forward of the vacuum inlet;
wherein the first wheel of the drive system is disposed aft of the first side brush on a first side of the vacuum inlet; and
wherein the second wheel of the drive system is disposed aft of the second side brush on a second side of the vacuum inlet.
2. The robot of claim 1 , wherein the first side brush includes bristles extending from a hub.
3. The robot of claim 2 , wherein the hub is a first hub, and the second side brush includes bristles extending from a second hub.
4. The robot of claim 3 , wherein the bristles of the first side brush are configured to contact the first wheel of the drive system when the first side brush rotates and wherein the bristles of the second side brush are configured to contact the second wheel of the drive system when the second side brush rotates.
5. The robot of claim 3 , wherein the bristles of the first side brush and the bristles of the second side brush are configured to extend past an outer edge of the robot.
6. The robot of claim 3 , wherein the bristles of the first side brush and the bristles of the second side brush are configured to pass underneath a portion of a bump sensor on the robot.
7. The robot of claim 3 , wherein the bristles of the first side brush and the bristles of the second side brush are configured to pass beneath a portion of the vacuum inlet.
8. The robot of claim 1 , wherein the first side brush includes three arms spaced at approximately 120 degree angles from one another.
9. The robot of claim 8 , wherein the second side brush includes three arms spaced at approximately 120 degree angles from one another.
10. The robot of claim 1 , further comprising a caster wheel that is disposed between the first side brush and the second side brush and forward of the vacuum inlet.
11. The robot of claim 1 , further comprising a bump sensor supported on the forward portion of the robot and responsive to a collision of the robot with an obstacle, wherein the robot is configured to maneuver via the drive system in response to detecting a bump signal from the bump sensor, and wherein the cliff sensors are disposed less than five centimeters from the bump sensor.
12. The robot of claim 11 , wherein the bump sensor comprises at least two portions, wherein the robot turns at least a minimum angle in a counter-clockwise rotation in response to detecting the bump signal, and wherein a value of the minimum angle is based on which portion, of the at least two portions of the bump sensor, sends the bump signal.
13. The robot of claim 1 , further comprising a main brush that is rotatably attached to the robot, the main brush configured to sweep debris from the floor surface towards the vacuum inlet.
14. The robot of claim 1 , wherein the robot is circular in shape, and wherein the forward portion defines an arcuate forward edge.
15. The robot of claim 1 , further comprising a debris bin disposed aft of the vacuum inlet and the drive system.
16. The robot of claim 1 , wherein one or more of the cliff sensors comprise an infrared emitter and an infrared detector, and wherein the infrared emitter and the infrared detector are angled relative to the floor surface.
17. The robot of claim 16 , wherein the infrared emitter is configured to modulate an infrared signal.
18. The robot of claim 1 , further comprising a wall sensor, wherein the robot is configured to turn away from a wall in response to detecting the wall with the wall sensor, and wherein the robot is further configured to turn back toward the wall about a turn radius in response to the wall sensor no longer detecting the wall.
19. The robot of claim 18 , wherein the robot is configured to decrease a value of the turn radius while turning back toward the wall, the value of the turn radius being decreased relative to an initial value of the turn radius.
20. The robot of claim 18 , wherein the robot is configured to determine that the wall includes a corner based on a signal from the wall sensor, and wherein the robot is configured to navigate around the corner in response to the detecting.