System and method for robot safety and collision avoidance

1. A robot safety system comprising:

a robot having a plurality of mobile components, each instrumented with a plurality of proximity sensors adapted to develop a respective intrusion detection zone substantially surrounding said mobile component, each sensor adapted to detect an intrusion into a respective portion of the zone;

a model of at least one predefined robot application comprising, for each of the intrusion detection zones, a set of accepted intrusions during each of a plurality of predefined time intervals comprising the application;

a controller adapted to:

control the robot to execute the application;

during each time interval of the application, monitor for detected intrusions into each of the intrusion detection zones; and

trigger an interrupt of the application in response to a detected intrusion into any one of said intrusion detection zones not in the set of accepted intrusions for said one intrusion detection zone for the respective time interval.

2. A method for operating a robot having a plurality of mobile components, the method comprising the steps of:

during a first time period:

instrumenting a robot with a plurality of proximity sensors so as to develop a respective intrusion zone substantially surrounding each of the mobile components of the robot, each sensor adapted to detect an intrusion into a respective portion of the zone; and

modeling at least one predefined robot application to develop, for each of the intrusion detection zones, a set of accepted intrusions during each of a plurality of predefined time intervals comprising the application;

during a second time period:

executing the application;

during each time interval of the application, monitoring for detected intrusions into each of the intrusion detection zones; and

triggering an interrupt of the application in response to a detected intrusion into any one of said intrusion detection zones not in the set of accepted intrusions for said one intrusion detection zone for the respective time interval.

3. A robot safety system comprising:

a robot having a plurality of mobile components, each instrumented with a plurality of sensors so as to develop a respective intrusion zone substantially surrounding said mobile component, each sensor adapted to develop a respective sensor signal;

a model of at least one predefined robot operation comprising a set of expected sensor signals for each sensor at each of a plurality of predefined time intervals comprising the operation;

a controller adapted to:

control the robot to execute the operation;

at each of the predefined time intervals, correlate the sensor signal developed by each of the sensors during the operation to the respective expected sensor signal; and

signaling an exception if the developed sensor signal and the expected sensor signal do not correlate.

4. The method of claim 3 , wherein the modeling is further characterized as comprising:

a model of robot components, workcell equipment and operators comprising a set of expected sensor signals for each sensor at predefined time intervals in an operation of the robot due to intrusions of other robot components, workcell equipment and operators.

5. The method of claim 3 , further comprising the step of:

in response to a signaled exception indicative of an unexpected intrusion of an object, determining a corrective action so as to avoid undesired collision with the intruding object.

6. A method for operating a robot, comprising the steps of:

instrumenting a robot with a plurality of sensors so as to develop an intrusion zone surrounding each of a plurality of mobile components of the robot, each sensor adapted to develop a respective sensor signal;

modeling at least one predefined robot operation to develop an expected sensor signal for each sensor at each of a plurality of predefined time intervals comprising the operation;

executing the operation;

at each of the predefined time intervals, correlating the sensor signal developed by each of the sensors during the operation to the respective expected sensor signal; and

signaling an exception if the developed sensor signal and the expected sensor signal do not correlate.

7. The method of claim 6 , wherein the modeling step is further characterized as comprising:

modeling robot components, workcell equipment and operators to determine expected sensor signals for each sensor at predefined time intervals in an operation of the robot due to intrusions of other robot components, workcell equipment and operators.

8. The method of claim 6 , further comprising the step of:

in response to a signaled exception indicative of an unexpected intrusion of an object, determining a corrective action so as to avoid undesired collision with the intruding object.

9. The method of claim 8 , further comprising the step of:

determining a distance between the intruding object and a nearest movable component of the robot; and

determining a rate of change of the determined distance.

10. The method of claim 6 , wherein the modeling step is further characterized as comprising:

modeling robot components to develop a time based map of the signal developed by each sensor during each time interval of the operation.

11. A method for improved safety of industrial robots by avoiding undesired collisions, comprising:

instrumenting a robot with a plurality of sensors to create an intrusion zone around each of a plurality of movable components of the robot, each sensor adapted to develop a sensor signal during an operation of the robot;

modeling each robot component to determine expected sensor signals for each sensor at predefined time intervals in the operation of the robot due to intrusions of other robot components; and

during each time interval of the operation of the robot:

correlating each developed sensor signal to the respective expected sensor signal; and

signaling an exception in response to a non-correlation.

12. The method of claim 11 , further comprising the step of:

modeling movements of workcell equipment and operators to determine expected sensor signals due to intrusions of the workcell equipment and operators.

13. The method of claim 11 , further comprising the step of:

in response to a signaled exception indicative of an unexpected intrusion of an object, determining a corrective action so as to avoid undesired collision with the intruding object.

14. The method of claim 13 , further comprising the step of:

determining a distance between the intruding object and a nearest movable component of the robot; and

determining a rate of change of the determined distance.

15. The method of claim 11 , wherein the modeling step is further characterized as comprising:

modeling robot components, workcell equipment and operators to determine expected sensor signals for each sensor at predefined time intervals in an operation of the robot due to intrusions of other robot components, workcell equipment and operators.

16. The method of claim 11 , wherein the modeling step is further characterized as comprising:

modeling robot components to develop a time based map of the signal developed by each sensor during each time interval of the operation.

17. The method of claim 11 , wherein each sensor is adapted to detect proximity of objects.