Robotic guarded motion system and method
View Patent ↗A robot platform includes perceptors, locomotors, and a system controller. The system controller executes instructions for repeating, on each iteration through an event timing loop, the acts of defining an event horizon, detecting a range to obstacles around the robot, and testing for an event horizon intrusion. Defining the event horizon includes determining a distance from the robot that is proportional to a current velocity of the robot and testing for the event horizon intrusion includes determining if any range to the obstacles is within the event horizon. Finally, on each iteration through the event timing loop, the method includes reducing the current velocity of the robot in proportion to a loop period of the event timing loop if the event horizon intrusion occurs.
1. A method for controlling motion of a robot, comprising:
repeating on each iteration through an event timing loop, the acts of:
defining an event horizon comprising a distance from the robot that is proportional to a current velocity of the robot;
detecting a range to obstacles around the robot;
testing for an event horizon intrusion by determining if any range to the obstacles is within the event horizon; and
reducing the current velocity of the robot in proportion to a loop period of the event timing loop if the event horizon intrusion occurs.
2. The method of claim 1 , wherein reducing the current velocity comprises reducing a current translational velocity and reducing a current rotational velocity.
3. The method of claim 1 , wherein repeating on each iteration through the event timing loop is performed at least for each of the directions of forward, left, right and back relative to a current pose of the robot.
4. The method of claim 1 , wherein repeating on each iteration through the event timing loop further comprises the acts of:
testing sensory signals indicating that the robot has contacted an obstacle and if contact is detected, then:
modifying a direction of motion for the robot to be in an opposite direction from the contacted obstacle;
modifying the current velocity for the robot to be a fractional portion of a predetermined maximum velocity; and
foregoing the acts of testing for the event horizon intrusion, and reducing the current velocity.
5. The method of claim 1 , wherein repeating on each iteration through the event timing loop further comprises the acts of:
testing for a resistance to motion in a current direction and if the resistance is detected, then:
halting motion in the current direction; and
foregoing the acts of testing for the event horizon intrusion, and reducing the current velocity.
6. The method of claim 5 , wherein testing for a resistance to motion comprises the detection of resistance by:
testing that locomotor acceleration is substantially near zero;
testing that locomotor force is greater than zero; and
testing that inertial acceleration of the robot is below a predefined inertial threshold.
7. The method of claim 1 , wherein repeating on each iteration through an event timing loop further comprises the acts of:
defining a danger zone comprising a predetermined distance from the robot;
after the act of reducing the current velocity, testing for a danger zone intrusion by determining if any range to the obstacles is within the danger zone; and
stopping motion in a current direction if the danger zone intrusion occurs.
8. The method of claim 1 , wherein the loop period is adjusted based on a current work load of a system controller on the robot.
9. A computer readable medium having computer instructions thereon, which when executed on a system controller provide a method for controlling motion of a robot, the computer instructions comprising instructions for:
repeating on each iteration through an event timing loop, the acts of:
defining an event horizon comprising a distance from the robot that is proportional to a current velocity of the robot;
detecting a range to obstacles around the robot;
testing for an event horizon intrusion by determining if any range to the obstacles is within the event horizon; and
reducing the current velocity of the robot in proportion to a loop period of the event timing loop if the event horizon intrusion occurs.
10. The computer readable medium of claim 9 , wherein reducing the current velocity comprises reducing a current translational velocity and reducing a current rotational velocity.
11. The computer readable medium of claim 9 , wherein repeating on each iteration through the event timing loop is performed at least for each of the directions of forward, left, right and back relative to a current pose of the robot.
12. The computer readable medium of claim 9 , wherein repeating on each iteration through the event timing loop further comprises the acts of:
testing sensory signals indicating that the robot has contacted an obstacle and if contact is detected, then:
modifying a direction of motion for the robot to be in an opposite direction from the contacted obstacle;
modifying the current velocity of the robot to be a fractional portion of a predetermined maximum velocity; and
foregoing the acts of testing for the event horizon intrusion, and reducing the current velocity.
13. The computer readable medium of claim 9 , wherein repeating on each iteration through the event timing loop further comprises the acts of:
testing for a resistance to motion in a current direction and if the resistance is detected, then:
halting motion in the current direction; and
foregoing the acts of testing for the event horizon intrusion, and reducing the current velocity.
14. The computer readable medium of claim 13 , wherein testing for a resistance to motion comprises the detection of resistance by:
testing that locomotor acceleration is substantially near zero;
testing that locomotor force is greater than zero; and
testing that inertial acceleration of the robot is below a predefined inertial threshold.
15. The computer readable medium of claim 9 , wherein repeating on each iteration through an event timing loop further comprises the acts of:
defining a danger zone comprising a predetermined distance from the robot;
after the act of reducing the current velocity, testing for a danger zone intrusion by determining if any range to the obstacles is within the danger zone; and
stopping motion in a current direction if the danger zone intrusion occurs.
16. The computer readable medium of claim 9 , wherein the loop period is adjusted based on a current work load of a system controller on the robot.
17. A robot platform, comprising:
at least one perceptor configured for perceiving environmental variables of interest;
at least one locomotor configured for providing mobility to the robot platform;
a system controller configured for executing computer instructions configured for controlling motion of a robot, the computer instructions comprising instructions for:
repeating on each iteration through an event timing loop, the acts of:
defining an event horizon comprising a distance from the robot that is proportional to a current velocity of the robot;
detecting a range to obstacles around the robot;
testing for an event horizon intrusion by determining if any range to the obstacles is within the event horizon; and
reducing the current velocity of the robot in proportion to a loop period of the event timing loop if the event horizon intrusion occurs.
18. The robot platform of claim 17 , wherein reducing the current velocity comprises reducing a current translational velocity and reducing a current rotational velocity.
19. The robot platform of claim 17 , wherein repeating on each iteration through the event timing loop is performed at least for each of the directions of forward, left, right and back relative to a current pose of the robot.
20. The robot platform of claim 17 , wherein repeating on each iteration through the event timing loop further comprises the acts of:
testing sensory signals indicating that the robot has contacted an obstacle and if contact is detected, then:
modifying a direction of motion for the robot to be in an opposite direction from the contacted obstacle;
modifying the current velocity for the robot to be a fractional portion of a predetermined maximum velocity; and
foregoing the acts of testing for the event horizon intrusion, and reducing the current velocity.
21. The robot platform of claim 17 , wherein repeating on each iteration through the event timing loop further comprises the acts of:
testing for a resistance to motion in a current direction and if the resistance is detected, then:
halting motion in the current direction; and
foregoing the acts of testing for the event horizon intrusion, and reducing the current velocity.
22. The robot platform of claim 21 , wherein testing for a resistance to motion comprises the detection of resistance by:
testing that locomotor acceleration is substantially near zero;
testing that locomotor force is greater than zero; and
testing that inertial acceleration of the robot is below a predefined inertial threshold.
23. The robot platform of claim 17 , wherein repeating on each iteration through an event timing loop further comprises the acts of:
defining a danger zone comprising a predetermined distance from the robot;
after the act of reducing the current velocity, testing for a danger zone intrusion by determining if any range to the obstacles is within the danger zone; and
stopping motion in the current direction if the danger zone intrusion occurs.
24. The robot platform of claim 17 , wherein the loop period is adjusted based on a current work load of the system controller.