System and method for jerk limited trajectory planning for a path planner

• US 7,919,940 B2
• Filed: 10/21/2007
• Issued: 04/05/2011
• Est. Priority Date: 10/21/2007
• 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): Ro; Bentsu
• Application Number:
  US11/875,913
• Publication Number:
  US 20090102411A1
• Time in Patent Office: 1,262 Days
• Field of Search: 318162-164, 318/560, 318/565, 318/626, 318/636, 318/652, 318569-573, 388/904
• US Class Current: 318/163
• CPC Class Codes: G05B 19/19 characterised by positioning or contouring control systems, e.g. to control position from one programmed point to another or to control movement along a programmed continuous path
• CPC Class Codes: G05B 19/416 characterised by control of velocity, acceleration or deceleration G05B19/19 takes precedence
• CPC Class Codes: G05B 2219/41408 Control of jerk, change of acceleration
• CPC Class Codes: G05B 2219/43168 Motion profile planning for point to point control
• CPC Class Codes: Y10S 388/904 Stored velocity profile

Abstract

A system for generating a motion profile in real time includes a processor. The processor breaks a move into a first phase and a second phase. The first phase includes commanding the move toward a constant velocity segment, and the second phase includes monitoring the first phase to determine when during a move in progress it is necessary to implement a jerk value required to successfully reach end conditions. The processor also transmits command signals based upon the motion profile and calculates the point at which the second phase must take control of the move in progress to reach a target position. The system further includes at least one input/output module that receives command signals. A method for generating a motion profile in real time is also presented.

Claims

1. A system for generating a motion profile in real time, the system comprising a processor, the processor configured to:

break a move into a first phase and a second phase, the first phase comprising commanding the move toward a constant velocity segment, and the second phase comprising monitoring the first phase to determine when during a move in progress it is necessary to implement a jerk value required to successfully reach end conditions;

calculate a jerk value required to successfully reach the end conditions for a current sample period (J_n);

calculate a jerk value required to successfully reach the end conditions for a next sample period (J_n+1); and

compare the calculated jerk value required for the current sample period (J_n) and the calculated jerk value required for the next sample period (J_n+1) to a commanded jerk value (J_c).

2. The system of claim 1, the processor further configured to:

implement the jerk value required to successfully reach the end conditions at a point at which the second phase takes control of the move in progress,

wherein the point at which the second phase takes control of the move in progress can occur any time after the first phase begins.

3. The system of claim 1, the processor further configured to:

split processing of first phase calculations and second phase calculations across sample periods.

4. The system of claim 1, the processor further configured to:

generate the motion profile without violating programmed limit values, the motion profile exhibiting a shortest-time path to reach a target position, wherein the jerk value required to successfully reach the end conditions is implemented on a sample period.

5. The system of claim 4, the processor further configured to:

abort the move in progress upon receiving at least one user-specified new move command value, wherein the at least one new move command value docs not violate the programmed limit values; and

continue the move implementing the at least one new command value.

6. The system of claim 4, the processor further configured to:

generate a warning upon receiving at least one user-specified new move command value, wherein the at least one new move command value violates the programmed limit values; and

continue the move in progress using existing command values.

7. The system of claim 1, the processor further configured to:

determine a number of discrete time segments required to complete the move,

wherein the motion profile comprises a plurality of discrete time segments between an initial position and a target position.

8. The system of claim 7, wherein:

a point at which the second phase takes control of the move in progress begins concurrently with one of the plurality of discrete time segments.

9. The system of claim 1, the processor further configured to:

apply correct signs to input command values, wherein input command values for jerk, velocity, acceleration, and deceleration arc user-specified as absolute values.

10. The system of claim 1, the processor further configured to:

implement the jerk value required to successfully reach the end conditions at a point at which the second phase takes control of the move in progress,

wherein the point at which the second phase takes control occurs when the commanded jerk value (J_c) is between the calculated jerk value for the current sample period (J_n) and the calculated jerk value for the next sample period (J_n+1).

11. The system of claim 10, wherein the jerk value required to successfully reach the end conditions is implemented at a time (n) of the current sample period.

12. The system of claim 1, the processor further configured to:

implement the calculated jerk value for the current sample period (J_n) at a point at which the second phase takes control of the move in progress,

wherein the point at which the second phase takes control occurs at a time (n) of the current sample period when the commanded jerk value (J_c) is between the calculated jerk value for the current sample period (J_n) and the calculated jerk value for the next sample period (J_n+1).

13. A system for generating a motion profile in real time, the system comprising:

at least one input/output module configured to receive command signals; and

a processor, the processor configured to;

transmit the command signals based upon the motion profile;

break a move into a first phase and a second phase;

calculate a point at which the second phase must take control of a move in progress in order to reach a target position;

calculate a jerk value required to successfully reach end conditions for a current sample period (J_n);

calculate a jerk value required to successfully reach the end conditions for a next sample period (J_n+1); and

compare the calculated jerk value required for the current sample period (J_n) and the calculated jerk value required for the next sample period (J_n+1) to a commanded jerk value (J_c).

14. The system of claim 13, wherein:

the point at which the second phase must take control of the move in progress occurs on a sample period, and

wherein the point at which the second phase must take control of the move in progress can occur any time after the first phase begins.

15. The system of claim 13, the processor further configured to:

implement a jerk value required to successfully reach end conditions at the point at which the second phase must take control of the move in progress.

16. A method for generating a motion profile in real time, the method comprising:

breaking a move into a first phase and a second phase;

commanding the move toward a constant velocity segment during the first phase;

monitoring the first phase to determine when during a move in progress it is necessary to implement a jerk value required to successfully reach end conditions;

calculating a jerk value required to successfully reach the end conditions for a current sample period (J_n);

calculating a jerk value required to successfully reach the end conditions for a next sample period (J_n+1); and

comparing the calculated jerk value required for the current sample period (J_n) and the calculated jerk value required for the next sample period (J_n+1) to a commanded jerk value (J_c).

17. The method of claim 16, further comprising:

implementing the jerk value required to successfully reach the end conditions at a point at which the second phase takes control of the move in progress,

wherein the point at which the second phase takes control of the move in progress can occur any time after the first phase begins.

18. The method of claim 16, further comprising:

generating the motion profile without exceeding programmed limit values, the motion profile exhibiting a shortest-time path to reach a target position, wherein the jerk value required to successfully reach the end conditions is implemented on a sample period.

19. The method of claim 16, further comprising:

implementing the a jerk value required to successfully reach the end conditions at a point at which the second phase takes control of the move in progress,

wherein the point at which the second phase takes control occurs when the commanded jerk value (J_c) is between the calculated jerk value for the current sample period (J_n) and the calculated jerk value for the next sample period (J_n+1).

20. The method of claim 16, further comprising:

implementing the calculated jerk value for the current sample period (J_n) at a point at which the second phase takes control of the move in progress,

wherein the point at which the second phase takes control occurs at a time (n) of the current sample period when the commanded jerk value (J_c)is between the calculated jerk value for the current sample period (J_n)the calculated jerk value for the next sample period (J_n+1).