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 mobile robot comprising:
a drive mechanism that both drives the robot forward in a drive direction and turns the robot to change the drive direction;
a sensor responsive to proximity of objects near a lateral side of the robot; and
a drive controller that controls the drive mechanism to drive the robot to follow a sensed object proximate the lateral side of the robot, the drive controller configured to monitor the sensor to detect when a followed object is no longer proximate the lateral side of the robot, to initiate a turn of the robot toward the lateral side in accordance with a turning radius in response to detecting that the followed object is no longer proximate the lateral side, and then to progressively decrease the turning radius of the robot over time while driving the robot forward, thereby causing the robot to progressively turn more sharply until the robot encounters a change in sensory input,
wherein the controller is configured to stop turning the robot if the robot reaches a predetermined maximum turn angle while monitoring the sensor, and to then move the robot forward along the drive direction.
2. The mobile robot of claim 1 , wherein the controller is configured to stop decreasing the turning radius if the robot bumps an object.
3. The mobile robot of claim 1 , wherein the sensor is a reflection detector, and wherein the controller detects that the followed object is no longer proximate the lateral side upon a transition from a reflection state to a non-reflection state of the sensor.
4. The mobile robot of claim 1 , wherein the controller is configured to stop decreasing the turning radius of the robot if the sensor detects an object on the lateral side.
5. The mobile robot of claim 1 , further comprising a floor cleaner disposed on the lateral side of the robot.
6. The mobile robot of claim 5 , wherein the floor cleaner includes a side brush extending beyond a lateral extent of a housing of the robot, the side brush driven to sweep debris from a floor surface beyond the lateral extent of the housing, for collection by the robot.
7. The mobile robot of claim 1 , wherein
the sensor is responsive to proximity of a room wall; and
the controller is configured to
drive the robot to follow a proximate wall on the lateral side of the robot by changing a turning radius to maintain a continuous detection of the wall by the sensor,
monitor the sensor to detect when the wall is no longer proximate the lateral side of the robot, and
in response to detecting that the wall is no longer proximate the lateral side, turning the robot toward the lateral side while decreasing the turning radius of the robot.
8. The mobile robot of claim 7 , wherein the controller is configured to, in response to the robot bumping into an object while following a wall,
turn the robot through a first angle, then monitor the sensor for wall detection while continuing to turn the robot, and then,
in response to wall detection and a subsequent cessation of wall detection, stop turning the robot.
9. The mobile robot of claim 8 , further comprising a bump sensor, and wherein the first angle is determined according to an angle at which the bump sensor indicates a bump.
10. A mobile robot, comprising:
a drive mechanism that both drives the robot forward across a floor in a drive direction and turns the robot to change the drive direction;
a sensor responsive to proximity of an object to be followed on a lateral side of the robot;
a floor area cleaner disposed on the lateral side of the robot; and
a drive controller that controls the drive mechanism to turn the robot to follow the object on the lateral side of the robot, by changing a robot turning radius to maintain continuous detection of the object by the sensor, including turning the robot toward the lateral side while progressively decreasing the robot turning radius in response to cessation of detection of the object proximate the lateral side.
11. The mobile robot of claim 10 , wherein the controller sets an initial turning radius and steadily decreases the turning radius until the robot bumps against an object.
12. The mobile robot of claim 10 , wherein the controller controls the drive mechanism to follow a path having a turning radius proportional to an angle of turn.
13. The mobile robot of claim 10 , wherein the sensor is a reflection detector, and wherein the controller determines cessation of detection of the object upon the sensor transitioning from a reflection state to a non-reflection state.
14. The mobile robot of claim 10 , wherein the controller decreases the robot turning radius until the sensor detects an object on the lateral side.
15. The mobile robot of claim 10 , wherein the floor area cleaner comprises a side brush extending beyond a lateral extent of a housing of the robot, the side brush driven to sweep debris from a floor surface beyond the lateral extent of housing for collection by the robot.
16. The mobile robot of claim 10 , wherein the sensor is responsive to proximity of a room wall, and wherein the controller drives the robot to follow a proximate wall on the lateral side of the robot by changing a turning radius to maintain continuous detection of the wall by the sensor, including turning the robot toward the lateral side while decreasing the turning radius of the robot in response to cessation of detection of the wall proximate the lateral side.
17. A mobile robot comprising:
a robot housing;
a drive mechanism that both drives the robot housing forward in a drive direction and turns the robot housing to change the drive direction;
a bump sensor responsive to the robot bumping into an object in the drive direction;
a proximity sensor responsive to proximity of a wall to be followed on a lateral side of the robot housing;
a side brush extending beyond a lateral extent of the housing, the side brush driven to sweep debris from a floor surface beyond the lateral extent of the housing, for collection by the robot; and
a drive controller that controls the drive mechanism to follow the wall on the lateral side of the robot, the drive controller configured to monitor the sensor to detect when the wall is no longer proximate the lateral side of the robot, in response to detecting that the wall is no longer proximate the lateral side, initiate a turn of the robot toward the lateral side in accordance with a turning radius in response to detecting that the followed wall is no longer proximate the lateral side, and then progressively decrease the turning radius of the robot over time while driving the robot forward, thereby causing the robot to progressively turn more sharply until one of the sensors detects a wall on the lateral side,
wherein the controller is configured to stop turning the robot if the robot reaches a predetermined maximum turn angle while monitoring the sensor, and to then move the robot housing forward along the drive direction.