System and method for path planning

• US 8,024,069 B2
• Filed: 01/28/2009
• Issued: 09/20/2011
• Est. Priority Date: 01/28/2009
• Status: Active Grant

• Current Assignee: Intelligent Platforms, LLC (Emerson Electric Company)
• Original Assignee: GE Intelligent Platforms Incorporated (Emerson Electric Company)
• Inventors: Morrison, William Lindsay, Miller, Daniel H.
• Primary Examiner(s): BARNES-BULLOCK, CRYSTAL JOY
• Application Number:
  US12/361,170
• Publication Number:
  US 20100191351A1
• Time in Patent Office: 965 Days
• Field of Search: 700/56, 700 61- 64, 700/245, 700/246, 700/250, 700253-255, 701/2, 701/23, 701/25, 701/26, 701200-202, 701/204, 701/207, 701/209, 701/210, 701/300, 701/301, 702/127, 702/150, 318/162, 318/163, 318/560, 318/561, 318/567, 318/568.11, 318/568.12, 318/575, 318/580, 342/350, 342/352, 342/357.2, 342/357.39, 342/357.4, 342/357.42, 345/418, 345/473, 345/474
• US Class Current: 700/253
• CPC Class Codes: B65C 9/40 Controls; Safety devices
• CPC Class Codes: G05B 19/18 Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to execute positioning, movement or co-ordinated operations by means of programme data in numerical form G05B19/418 takes precedence
• CPC Class Codes: G05B 2219/25473 Compensation variable cycle time, synchronized processes
• CPC Class Codes: G05B 2219/42186 Master slave, motion proportional to axis
• CPC Class Codes: G05B 2219/42188 Slave controlled as function of reference and actual position and derived speed of master

Abstract

A method for mapping a motion of a first object within a first motion path defined by a path planner based on a second motion path of a second object. The method includes creating the first motion path for the first object using the path planner, initializing a start position of the first object within the first motion path, determining a value for an initial condition for each segment of a plurality of segments in the first motion path created by the path planner, and calculating an elapsed time between a current sample call time to the path planner and a last sample call time to the path planner. If the calculated elapsed time is one of greater than and less than a sample period, a current location of the second object in the second motion path is determined utilizing the calculated elapsed time, an expired time within a first segment of the plurality if segments between a start time of the first segment and the current sample call time is calculated, and an output command is generated from the path planner. Execution of the generated output command alters the first motion path.

Claims

1. A method for mapping a motion of a first object within a first motion path defined by a path planner based on a second motion path of a second object, the method comprising:

creating the first motion path for the first object using the path planner;

initializing a start position of the first object within the first motion path;

determining a value for an initial condition for each segment of a plurality of segments in the first motion path created by the path planner;

calculating an elapsed time between a current sample call time to the path planner and a last sample call time to the path planner;

if the calculated elapsed time is one of greater than and less than a sample period, determine a current location of the second object in the second motion path utilizing the calculated elapsed time;

calculating an expired time within a first segment of the plurality of segments between a start time of the first segment and the current sample call time; and

generating an output command from the path planner, the execution of the generated output command altering the first motion path.

2. A method in accordance with claim 1, wherein the initial condition comprises one of the following:

a jerk constrained motion, a calculated value for position, a velocity, and an acceleration value at switching points.

3. A method in accordance with claim 1, wherein the expired time is a time passed an initial set time for each segment.

4. A method in accordance with claim 3, wherein the start time is set by the path planner.

5. A method in accordance with claim 1, wherein the output command includes a command for one of the following:

a position, a velocity, an acceleration, and a jerk.

6. A system for mapping continuous time kinematic motion equations into a discrete time domain, the system comprising:

a memory area for storing path planner information including an initial time a first motion path was planned and an initial condition for each segment of a plurality of segments in the first motion path, the plurality of segments defined by discontinuities introduced by the continuous time kinematic motion equations; and

a processor programmed to;

create the first motion path for a first object using the path planner based on a second motion path of a second object;

initialize a start position of the first object within the first motion path;

determine a value for an initial condition for each segment created by the path planner;

calculate an elapsed time between a current sample call time to the path planner and a last sample call time to the path planner;

if the calculated elapsed time is one of greater than and less than a sample period, determine a current location of the second object in the second motion path utilizing the calculated elapsed time;

calculate an expired time within a first segment of the plurality of segments between a start time of the first segment and the current sample call time; and

generate an output command from the path planner, the execution of the generated output command altering the first motion path.

7. A system in accordance with claim 6, wherein the processor is further programmed to access a calculated value for an initial condition for each segment stored in the memory area.

8. A system in accordance with claim 6, wherein the processor is further programmed to access the initial time the path was planned.

9. A system in accordance with claim 6, wherein the initial condition is one of the following:

a jerk constrained motion, a calculated value for a position, a calculated value for a velocity, and an acceleration value.

10. A system in accordance with claim 6, wherein the expired time within the first segment is a time passed an initial set time for the first segment.

11. A system in accordance with claim 10, wherein the initial set time is set by the path planner.

12. A system in accordance with claim 6, wherein the output command is a command for one of the following:

a position, a velocity, an acceleration, and a jerk.

13. A computer readable medium storing a program instructing a computer to perform a method for mapping continuous time kinematic motion equations into a discrete time domain, the instructions comprising:

creating a first motion path for a first object using a path planner;

initializing a start position of the first object within the first motion path;

determining a value for an initial condition for each segment of a plurality of segments in the first motion path created by the path planner;

calculating an elapsed time between a current sample call time to the path planner and a last sample call time to the path planner;

if the calculated elapsed time is one of greater than and less than a sample period, determining a current location of a second object in a second motion path utilizing the calculated elapsed time;

calculating an expired time within a first segment of the plurality of segments between a start time of the first segment and the current sample call time; and

generating an output command from the path planner, the execution of the generated output command altering the first motion path.

14. A computer readable medium in accordance with claim 13, wherein the initial condition is one of the following:

a jerk constrained motion, a calculated value for a position, a velocity, and an acceleration value at a switching point.

15. A computer readable medium in accordance with claim 13, wherein the time that has expired within the plurality of segments is a time passed an initial set time for each segment.

16. A computer readable medium in accordance with claim 15, wherein the initial set time for each segment is set by the path planner.

17. A computer readable medium in accordance with claim 13, wherein the output command includes a command for one of the following:

a position, a velocity, an acceleration, and a jerk.