Autonomous robot

Abstract

A method for communication between a charging station and a robot, via a pair of power lines coupled between a power supply in the charging station and a battery in the robot. In operation, the power supply is sequentially switched between a first voltage level and a second voltage level in accordance with a predetermined signal pattern. The voltage level on the power lines in the robot is monitored and correlated with a specific command to be executed by the robot.

1 . A method for communication between a charging station and a robot, via at least one pair of power lines coupled between a power supply in the charging station and a battery in the robot, the method comprising: sequentially switching the power supply between a first voltage level and a second voltage level in accordance with a predetermined signal pattern; and monitoring the voltage level on the power lines in the robot; wherein the signal pattern monitored by the robot is correlated with a specific command to be executed by the robot. 
     
     
         2 . The method of  claim 1 , wherein the command executed by the robot is selected from the group consisting of commands for activating a specific perimeter loop controlling the robot, commands for controlling a signal level on the perimeter loop, commands for indicating a battery type in the robot, commands for indicating the voltage of the battery in the robot, and commands for controlling an electronic irrigation system. 
     
     
         3 . The method of  claim 1 , wherein the power supply is switched in an ON and OFF sequence by a switch in the charging station to establish the signal pattern, and wherein the robot determines the signal pattern by monitoring the ON and OFF sequence. 
     
     
         4 . The method of  claim 1 , wherein the signal pattern is established by the robot by switching the power received on the power lines by the robot in an ON and OFF sequence by a switch in the robot, and wherein the charging station determines the signal pattern by monitoring the ON and OFF sequence via detection of respective voltage levels on the power lines, and wherein the signal pattern is correlated with the specific command to be executed by the charging station. 
     
     
         5 . The method of  claim 1 , wherein bidirectional communication is effected between the robot and the charging station by performing additional steps comprising: establishing a second signal pattern by switching the power received on the power lines by the robot in an ON and OFF sequence by a switch in the robot, wherein the charging station determines the second signal pattern by monitoring the ON and OFF sequence via detection of respective voltage levels on the power lines, and correlating the sequence with the specific command to be executed by the charging station. 
     
     
         6 . The method of  claim 5 , wherein the electrical current level, in lieu of the voltage level, on the power lines, is monitored to determine the signal pattern in the robot and the second signal pattern in the charging station. 
     
     
         7 . A method for scanning, by a robot, a work area to be covered by the robot, wherein the robot travels inside the work area in successive paths, each initiated when the robot changes direction, the method comprising: scanning the work area using a first scanning pattern; monitoring the length of each of the paths traveled by the robot; switching from the first scanning mode to a second scanning pattern when an obstacle is encountered on a minimum number of consecutive said paths each having a length between a first threshold distance and a longer, second threshold distance; and switching back to the first scanning pattern when the length of one of the paths has increased to more than the second threshold distance. 
     
     
         8 . The method of  claim 7 , wherein the first scanning pattern comprises the robot traveling in a random walk pattern, and wherein the second scanning pattern comprises the robot traveling in a pattern comprising alternating pairs of essentially parallel paths, wherein a first one of the paths in each of the alternating pairs is oriented at an angle between approximately 120 and 240 degrees from the angle of the immediately previous one of the paths. 
     
     
         9 . The method of  claim 7 , wherein, if a predetermined number of consecutive paths traveled by the robot are each shorter than the first threshold distance, determining that the robot has reached a corner, in response to which the robot performs a maneuver to exit from the corner. 
     
     
         10 . The method of  claim 7 , wherein the robot changes direction in the first scanning mode and in the second scanning mode when a work area boundary is encountered and when an obstacle is encountered. 
     
     
         11 . The method of  claim 7 , wherein the minimum number of consecutive paths is at least two. 
     
     
         12 . A method for maneuvering a robot to extricate a robot from a problem area comprising: saving the heading of the robot as heading H 1 , when the robot encounters a first obstacle; performing an in-place turn in a first direction; saving the heading of the robot as heading H 2 , when the robot encounters a second obstacle; performing a turn in the reverse direction of the first turn substantially toward the bisector of the sector bounded by headings H 1  and H 2 ; and continuing operation with a forward leg to move between the first obstacle and the second obstacle, in a heading whose angular direction is substantially equal to the bisected angle H 1 -H 2 . 
     
     
         13 . The method of  claim 12 , wherein the first obstacle and the second obstacle are selected from a combination of obstacles consisting of two solid obstacles, and one solid obstacle and a perimeter boundary wire. 
     
     
         14 . A method for maneuvering a robot to extricate a robot from within a problem area bounded partially by an obstacle comprising: (a) traversing a straight leg until an obstacle is encountered; (b) performing a turn in a first direction; (c) continuing a straight leg traverse; (d) determining whether the robot is still inside the problem area; and (e) repeating steps (a) and (b) until the robot is no longer inside the problem area. 
     
     
         15 . The method of  claim 14 , wherein the turn has an angular value of between approximately 10 and 30 degrees. 
     
     
         16 . The method of  claim 14 , wherein the step of determining whether the robot is still inside the problem area is performed by observing that a straight leg traversed by the robot is longer than a predetermined value.