Method and system for continuous motion digital probe routing

• US 6,052,628 A
• Filed: 05/28/1998
• Issued: 04/18/2000
• Est. Priority Date: 08/08/1997
• Status: Expired due to Term

• Current Assignee: Hurco Companies, Inc.
• Original Assignee: Cimplus, Inc.
• Inventors: Hong, Jaiwei
• Primary Examiner(s): Grant, William
• Assistant Examiner(s): RAPP, CHAD
• Application Number:
  US09/109,972
• Time in Patent Office: 691 Days
• Field of Search: 395/500.13, 395/500.14, 395/500.15, 700/56, 700/61, 700/63, 700/64, 700/161, 700/188, 700/195, 700/160, 700/163, 702/94, 702/95, 702/167, 702/168
• US Class Current: 700/195
• CPC Class Codes: G05B 19/41 characterised by interpolation, e.g. the computation of intermediate points between programmed end points to define the path to be followed and the rate of travel along that path G05B19/25, G05B19/31, G05B19/37, G05B19/39, G05B19/40 take precedence
• CPC Class Codes: G05B 2219/34146 Helical, spiral interpolation
• CPC Class Codes: G05B 2219/37198 Machine as measuring station, use tool or probe, in process incycle
• CPC Class Codes: G05B 2219/50137 Contact in probe, touch probe to detect contact, touch trigger
• CPC Class Codes: Y02P 90/02 Total factory control, e.g. smart factories, flexible manufacturing systems [FMS] or integrated manufacturing systems [IMS]

Abstract

A method and system for routing a digital probe which signals either a triggered or non-triggered state to continuously scan a part surface without having to return to a rest position each time the probe is triggered. The probe is carried by manufacturing equipment capable of moving in response to control signals and providing manufacturing equipment feedback signals indicating the current position of the probe. Continuous movement of the digital probe is achieved by testing the probe to determine if it is triggered or not at a series of closely spaced time intervals, and rotating a move vector (corresponding to desired probe velocity) in each computation cycle to alter the probe trajectory as a function of the operating state of the probe and its position during the previous computation cycle. These techniques allow relatively inexpensive digital probing systems to gather data at speeds comparable to those of much more expensive analog systems. Various computation algorithms for altering the move vector are possible, including increasing or decreasing one component of the move vector by a constant value depending on whether the probe is triggered or not. Another algorithm generates a spiral path around the position of the probe at the previous transition between the triggered and untriggered operating state.

Claims

1. A method of routing a digital probe around the surface of an object, the probe being capable of signaling a triggered operating state when it is within a predetermined distance from the surface of the object and a non-triggered operating state otherwise, the probe being mounted on a machine which is capable of responding to control signals to produce relative movement between the probe and the object, the method comprising the steps of:

(1) detecting the operating state of the probe;

(2) generating a control signal to vary the movement of the probe relative to the object based on the operating state of the probe;

(a) the control signal being such that the probe will be in continuous motion relative to the object even when the probe is in its triggered operating state;

(b) the control signal further being such that the motion of the probe will be in a direction which (i) will cause it to be triggered if it is in the untriggered state, and (ii) which will cause it to return to the untriggered state if it is in the triggered state; and

(3) moving the probe relative to the object according to the control signal.

2. A method according to claim 1 in which the control signal is generated to define the desired velocity of the probe.

3. A method according to claim 1, in which the machine is capable of signalling the position of the probe relative to the object;

and further including the steps of;

(1) detecting the position of the probe relative to the object;

(2) generating the control signal such that it is dependent on the position of the probe relative to the object as well as on the operating state of the probe.

4. A method according to claim 3, further including the steps of:

(1) detecting a change in the operating state of the probe;

(2) identifying the position of probe at each change of the operating state of the probe as a data point.

5. A method according to claim 1, further including the steps of:

(1) establishing a plane which intersects the object as an instantaneous probing plane;

(2) generating the control signal such that

(a) the movement of the probe will be substantially exclusively in the probing plane and

(b) further such that the motion of the probe

(i) will be predominantly in a first angular direction relative to a vector normal to the probing plane if the probe is in its non-triggered state; and

(ii) predominantly in the opposite angular direction relative to the vector normal to the probing plane if the probe is in its triggered state.

6. A method according to claim 5 in which

(1) the direction of the motion of the probe is counter-clockwise relative to the line normal to the probing plane when the probe is in its non-triggered state, and

(2) clockwise relative to the line normal to the probing plane when the probe is in its triggered state.

7. A method according to claim 5 in which the control signal is generated to define the desired velocity of the probe in the plane.

8. A method according to claim 1 in which the probe is triggered by contact with the surface of the object, and further including the step of:

(1) limiting further motion of the probe to a predetermined safe distance if the probe is triggered.

9. A method of routing a digital probe around the surface of an object, the probe being capable of signaling a triggered operating state when it is within a predetermined distance from the object surface and a non-triggered operating state otherwise, the probe being mounted on a machine which is capable of responding to control signals to produce relative movement between the probe and the object, and further capable of signalling the position of the probe relative to the object;

the method comprising the steps of;

(1) detecting the non-triggered or triggered operating state of the probe at a succession of computation times;

(2) detecting the position of the probe relative to the object at each computation time;

(3) generating a control signal at each computation time to vary the movement of the probe relative to the object based on the position of the probe relative to the object at the computation time and on the operating state of the probe at that computation time;

(4) the control signal further being such that

(a) the probe will be in continuous motion relative to the object even when the probe is in its triggered operating state, and

(b) such that the motion of the probe will tend to be in a direction

(i) which will cause the probe to be triggered if it was in the untriggered state at the computation time, and

(ii) which will cause it to return to the untriggered state if it was triggered at the computation time; and

(5) moving the probe relative to the object according to the control signal generated at one computation time during the interval until the next computation time.

10. A method according to claim 9 in which the control signal is generated to define the desired velocity of the probe.

11. A method according to claim 9, further including the steps of:

(1) establishing a plane which intersects the object as an instantaneous probing plane;

(2) generating the control signal such that the movement of the probe will be in the probing plane and

(3) further such that the motion of the probe

(a) will be predominantly in a first angular direction relative to a vector normal to the probing plane if the probe is in its non-triggered state at the computation time, and

(b) predominantly in the opposite angular direction relative to the vector normal to the probing plane if the probe is in its triggered state at the computation time.

12. A method according to claim 11 in which

(1) the change of direction of the motion of the probe is counter-clockwise relative to the line normal to the probing plane when the probe is in its non-triggered state, and

(2) clockwise relative to the line normal to the probing plane when the probe is in its triggered state.

13. A method according to claim 11, further comprising the steps of:

(1) comparing the operating state of the probe at successive computation times; and

(2) identifying the position of the probe at a particular computation time as a data point only if there has been an change of the probe'"'"'s operating state since the previous computation time.

14. A method according to claim 13, further comprising a step of:

(1) recording the series of data points obtained as a representation of the surface of the object.

15. A method according to claim 13, in which the step of generating the control signals comprises the additional step of:

(1) utilizing the previously identified data point and the instantaneous position of the probe at a particular computation time to define the trajectory of the probe until the next computation time.

16. A method according to claim 15 further including, after at least one computation time, the step of:

(1) selecting a new instantaneous probing plane.

17. A method according to claim 9 in which the probe is triggered by contact with the surface of the object, and further including the step of:

(1) limiting additional motion of the probe to a predetermined safe distance, if the probe is triggered.

18. A method according to claim 9 further comprising the steps of:

(1) comparing the operating state of the probe at successive computation times; and

(2) identifying the position of the probe at a particular computation time as a data point only if there has been an change of the operating state of the probe since the previous computation time.

19. A method according to claim 18 further comprising a step of:

(1) recording the series of data points obtained as a representation of the surface of the object.

20. A method according to claim 18 in which the step of generating the control signals comprises the additional step of:

(1) utilizing the previously identified data point and the instantaneous position of the probe at a particular computation time to define the trajectory of the probe until the next computation time.

21. A method according to claim 18, in which:

(1) the control signal is such that it tends to cause the probe to move in a spiral path around the previously identified data point.

22. A method according to claim 9, in which the step of generating the control signal further includes the steps of:

(1) generating a first component in a direction which causes the probe to be triggered and having a magnitude equal to a first constant value, and

(2) generating a second component in a direction orthogonal to the direction of the first component, the second component

(a) having a magnitude equal to a second constant value when the probe is triggered at a particular computation time, and

(b) a magnitude equal to the negative value of the second constant when the probe is untriggered at a particular computation time.

23. A method according to claim 9, in which the step of generating the control signal further includes the steps of:

(1) generating a first component in a direction which causes the probe to be triggered, and having a magnitude equal to a first constant value,

(2) generating a second component in a direction orthogonal to the direction of the first component,

(3) increasing the magnitude of the second component by a second constant value when the probe is triggered at a particular computation time, and

(4) decreasing the magnitude of the second component by the negative value of the second constant when the probe is untriggered at a particular computation time.

24. A method according to claim 18 in which the step of generating control signals further comprises the step of:

(1) determining the difference between the position of the probe at a particular computation time and the position of the previous data point, and, if the difference exceeds a predetermined safe value,

(a) preventing the difference from increasing further, thereby keeping the probe within a safe operating range.

25. A method according to claim 9 in which the probe is triggered by contact with the surface of the object, and further including the step of:

(1) permitting the motion of the probe to continue by only a predetermined additional distance, after the probe is triggered.

26. A method according to claim 9 further including, before initiating a succession of computation times, the step of:

(1) moving the probe toward the object until it is triggered, and thereafter, initiating the first computation time.

27. A method according to claim 26 in which:

(1) the step of moving the probe toward the object until it is triggered is performed by manually manipulating controls for the machine.

28. Apparatus for routing a digital probe around the surface of an object, the probe being capable of signaling a triggered operating state when it is within a predetermined distance from the surface of the object and a non-triggered operating state otherwise, the probe being mounted on a machine which is capable of responding to control signals to produce relative movement between the probe and the object, the apparatus comprising:

(1) means for detecting the operating state of the probe;

(2) means responsive to the operating state of the probe for generating a control signal to move the probe relative to the object continuously, irrespective of the operating state of the probe;

(3) the control signal generating means including;

(a) means responsive to the probe being in the untriggered state to generate a control signal which will cause the probe to be triggered, and

(b) means responsive to the probe being in the triggered state to generate a control signal which will cause the probe to be returned to the untriggered state; and

(4) means for coupling the control signal to the machine.

29. Apparatus according to claim 28, in which the machine is capable of generating signals representing the position of the probe relative to the part;

and in which the control signal generating means includes;

(1) means responsive to the probe position signals for generating a component of the control signal which is dependent on the position of the probe relative to the object.

30. Apparatus for according to claim 28 in which the control signal is representative of the desired velocity of the probe.

31. Apparatus for according to claim 28, further including:

(1) means for establishing a plane which intersects the object as an instantaneous probing plane; and

in which

(2) the control signal generating means includes;

(a) means for generating a first control signal for moving the probe substantially exclusively in the probing plane and predominantly in a first angular direction relative to a vector normal to the probing plane if the probe is in its non-triggered state;

(b) means for generating a second control signal for moving the probe substantially exclusively in the probing plane and predominantly in the opposite angular direction relative to the vector normal to the probing plane if the probe is in its triggered state.

32. Apparatus for according to claim 31 in which:

(1) the first direction is counter-clockwise relative to the line normal to the probing plane and in which;

(2) the second direction is clockwise relative to the line normal to the probing plane.

33. Apparatus for according to claim 32 in which:

(1) the first and second control signals represent the desired velocity of the probe in the probing plane.

34. Apparatus for routing a digital probe around the surface of an object, the probe being capable of signaling a triggered operating state when it is within a predetermined distance from the object surface and a non-triggered operating state otherwise, the probe being mounted on a machine which is capable of responding to control signals to produce relative movement between the probe and the object, and further capable of signalling the position of the probe relative to the object;

the apparatus comprising;

(1) means for detecting the operating state of the probe at a succession of computation times;

(2) means for detecting the position of the probe relative to the object at each computation time;

(3) means responsive to the operating state of the probe and the position of the probe for generating a control signal to maintain the probe constantly in motion irrespective of the operating state of the probe;

(a) the control signal generating means further including;

(i) means responsive to the probe being in its untriggered state at a particular computation time to generate a control signal which will tend to cause the probe to be triggered, and

(ii) means responsive to the probe being in the triggered state at the computation time, to generate a control signal which will tend to cause the probe to return to the untriggered state; and

(4) means for coupling the control signals to the machine.

35. Apparatus for according to claim 34 in which the control signal generating means includes means to generate the control signal to be representative of the desired velocity of the probe.

36. Apparatus according to claim 34, further including:

(1) means for establishing a plane which intersects the object as an instantaneous probing plane; and

in which

(2) the control signal generating means includes;

(a) means for generating a first control signal

(i) for moving the probe substantially exclusively in the probing plane and

(ii) predominantly in a first angular direction relative to a vector normal to the probing plane if the probe is in its non-triggered state at a particular computation time; and

(b) means for generating a second control signal

(i) for moving the probe substantially exclusively in the probing plane and

(ii) predominantly in the opposite angular direction relative to the vector normal to the probing plane if the probe is in its triggered state at the particular computation time.

37. Apparatus according to claim 36 in which:

(a) the first direction is counter-clockwise relative to the line normal to the probing plane, and in which

(b) the second direction is clockwise relative to the line normal to the probing plane when the probe.

38. Apparatus according to claim 36, further comprising:

(1) means for comparing the operating state of the probe at successive computation times; and

(2) means for identifying the position of the probe at a particular computation time as a data point only if there has been an change of the probe'"'"'s operating state since the previous computation time.

39. Apparatus according to claim 38, further comprising:

(1) means for recording the series of data points obtained as a representation of the surface of the object.

40. Apparatus for according to claim 38, in which the control signal generating means includes:

(1) means responsive to the previously identified data point and the instantaneous position of the probe at a particular computation time to define the trajectory of the probe until the next computation time.

41. Apparatus according to claim 36 further including means for selecting a new instantaneous probing plane.

42. Apparatus according to claim 34 further comprising:

(1) means for comparing the operating state of the probe at successive computation times; and

(2) means for identifying the position of the probe at a particular computation time as a data point only if there has been an change of the probe'"'"'s operating state since the previous computation time.

43. Apparatus according to claim 42 further comprising:

(1) means for recording the series of data points obtained as a representation of the surface of the object.

44. Apparatus according to claim 42 in which the control signal generating means includes means responsive to the previously identified data point and the instantaneous position of the probe at a particular computation time to define the trajectory of the probe until the next computation time.

45. Apparatus according to claim 42, in which the control signal generating means includes means to generate the control signal such that it tends to cause the probe to move in a spiral path around the previously identified data point.

46. Apparatus according to claim 42 in which the control signal generating means further comprises:

(1) means for determining the difference between the position of the probe at a particular computation time and the position of the last data point, and

(2) means responsive to the difference exceeding a predetermined safe value, for modifying the first control signal component to prevent the difference from increasing further, thereby keeping the probe within its safe operating range.

47. Apparatus according to claim 34 further including:

(1) means for moving the probe toward the object until it is triggered, and

(2) means for initiating a first computation time occurs once the probe has been triggered.

48. Apparatus according to claim 47 in which the means for moving the probe toward the object until it is triggered is a manual input device for the machine.

49. Apparatus according to claim 34 in which the control signal generating means includes:

(1) means for generating a first control signal component

(a) to move the probe in a direction which will cause it to be triggered and

(b) having a magnitude equal to a first constant value, and

(2) means for generating a second control signal component to move the probe in a direction which is orthogonal to the first control signal component;

the means for generating the second control signal component including;

(a) means for generating a signal which is equal in magnitude to a second constant value when the probe is triggered at a particular computation time, and

(b) equal to the negative value of the second constant when the probe is untriggered at a particular computation time.

50. Apparatus according to claim 34, in which the means for generating the control signal further includes:

(1) means for generating a first component

(a) for moving the probe in a direction which causes the probe to be triggered, and

(b) having a magnitude equal to a first constant value,

(2) means for generating a second component in a direction orthogonal to the direction of the first component,

(3) means for increasing the magnitude of the second component by a second constant value when the probe is triggered at a particular computation time, and

(4) means for decreasing the magnitude of the second component by the negative value of the second constant when the probe is untriggered at a particular computation time.