Apparatus and method for measurement of position and velocity

• US 5,779,241 A
• Filed: 06/02/1995
• Issued: 07/14/1998
• Est. Priority Date: 06/02/1995
• Status: Expired due to Fees

• Current Assignee: Minnesota Technology Transfer, Inc.
• Original Assignee: Minnesota Technology Transfer, Inc.
• Inventors: D'Costa, Joseph F., Rodgers, Timothy A., Erdman, Arthur G.
• Primary Examiner(s): Harrison, Jessica
• Application Number:
  US08/460,117
• Time in Patent Office: 1,138 Days
• Field of Search: 273/348, 273/371, 273/374, 273/394, 273/410, 273/26 A, 273/55 A, 273/55 B, 473/190, 473/191, 473/192, 473/194, 473/197, 463/53
• US Class Current: 273/371
• CPC Class Codes: A63B 2024/0037 on a target surface or at impact on the ground
• CPC Class Codes: A63B 2024/0043 Systems for locating the point of impact on a specific surface
• CPC Class Codes: A63B 2063/001 Targets or goals with ball-returning means
• CPC Class Codes: A63B 2102/02 Tennis
• CPC Class Codes: A63B 2102/18 Baseball, rounders or similar games
• CPC Class Codes: A63B 2102/182 Softball
• CPC Class Codes: A63B 2102/24 Ice hockey
• CPC Class Codes: A63B 2102/32 Golf
• CPC Class Codes: A63B 2220/30 Speed
• CPC Class Codes: A63B 2220/51 Force
• CPC Class Codes: A63B 2220/53 Force of an impact, e.g. blow or punch
• CPC Class Codes: A63B 2220/80 Special sensors, transducers or devices therefor
• CPC Class Codes: A63B 2243/0025 Football American football A63B2243/007
• CPC Class Codes: A63B 24/0021 Tracking a path or terminating locations
• CPC Class Codes: A63B 63/00 Targets or goals for ball games golf cups A63B57/40
• CPC Class Codes: A63B 69/0002 for baseball
• CPC Class Codes: A63B 69/002 for football American-football dummies A63B69/34
• CPC Class Codes: A63B 69/0026 for ice-hockey
• CPC Class Codes: A63B 69/3658 Means associated with the ball for indicating or measuring, e.g. speed, direction
• CPC Class Codes: A63B 69/38 for tennis A63B61/006, A63B69/0073 and A63B69/0097 take precedence
• CPC Class Codes: G01P 3/52 : by measuring amplitude of generated current or voltage
• CPC Class Codes: G01P 3/665 : for projectile velocity measurements

Abstract

A sensor for locating the position of and measuring the velocity of an impacting object. The sensor employs a net attached at each edge to sensor modules mounted on a frame. Each sensor module includes an output drum, a take up drum, a spring and a motor. The net is attached to the sensor modules by cords wound on a spring loaded output drum. The drum is coaxial with a motor that generates a voltage proportional to the angular velocity of the drum. The diode isolated motor partially dissipates the energy of impact to heat on the return stroke in response to the restorative force of the spring. An object impacting a net draws the cord from the output drum, generating a voltage from an attached motor. A maximum voltage or an integrated voltage generated by the motors determines the velocity of impact. Each particular net has an associated set of axes. A pair of motors, their position known relative to the frame, are placed along these axes attached to one or more strings by a cord. The position of impact is determined by the motors generating the largest voltage. Alternatively, the impact position may be determined by the two pairs of sensors generating the highest voltage, where the sensor pair is connected to the same string. A take up drum and a spring bias the system toward a rest position, returning the object to a predetermined area.

Claims

1. An apparatus for determining position and velocity of an object at impact, comprising:

(a) a frame having a plurality of sensor mounts and an outer edge;

(b) a plurality of sensor modules wherein one of the plurality of sensor mounts attaches a corresponding sensor module to the outer edge of the frame;

(c) a means for capturing an object wherein the means for capturing an object is located within the frame and attached to the plurality of sensor modules by a plurality of cords;

(d) a plurality of stops wherein one of the plurality of stops is attached to a corresponding one of the plurality of cords, wherein the plurality of stops provide a resting position for the apparatus at a predetermined point; and

(e) a controller attached to receive electronic signals from the plurality of sensor modules, wherein the controller determines at least one kinematic parameter.

2. The apparatus of claim 1, further comprising a backing mounted behind the means for capturing an object at a predetermined position to prevent overextension of the plurality of cords.

3. The apparatus of claim 1, further comprising a plurality of diode means wherein each one of the plurality of diode means is connected to one of the plurality of sensor modules for damping out a signal generated by the connected sensor module during return of the apparatus to resting position.

4. The apparatus of claim 1, wherein the controller determines velocity at impact using a peak voltage value.

5. The apparatus of claim 1, wherein the controller determines velocity at impact using a total voltage value.

6. The apparatus of claim 1, wherein the controller determines a location of impact using a location of a sensor module generating a highest voltage along a predetermined axis.

7. The apparatus of claim 1, wherein the controller determines a location of impact using a location of a pair of sensor modules generating a highest voltage along a predetermined axis.

8. The apparatus of claim 1, wherein the controller computes statistical, graphical and analytical information.

9. The apparatus of claim 1, further including a display unit connected to receive display data from the controller.

10. The apparatus of claim 9, wherein the display unit may display analytical, statistical or graphical information.

11. The apparatus of claim 1, wherein the apparatus returns an object impacting the apparatus to a predetermined location.

12. The apparatus of claim 1 further comprising a second means for capturing an object mounted behind the means for capturing an object.

13. The apparatus of claim 12 wherein the second means for capturing an object provides trajectory information.

14. The apparatus of claim 1 wherein the means for capturing an object comprises a net.

15. The apparatus of claim 14 wherein predetermined strings of the net are attached to one of the plurality of cords.

16. The apparatus of claim 1 wherein at least one of the plurality of sensor modules comprises:

a) an output drum rotatably attached to a sensor module and having an upper spindle, a lower spindle and an axis;

b) a take up drum attached to the lower spindle by a spring attached at a first end to the lower spindle and having a second end wound around the take up drum, wherein the spring biases the output drum to a rest state; and

c) a means for generating a voltage having a shaft, wherein the shaft is attached to the axis of the output drum, and the means for generating a voltage generates a voltage signal proportional to a rate of rotation.

17. The apparatus of claim 16, wherein the spring comprises a constant force spring.

18. The apparatus of claim 1, wherein the frame comprises a rectangle.

19. The apparatus of claim 18, wherein the plurality of sensor modules are attached to two perpendicular sides of the outer edge of the frame.

20. The apparatus of claim 1, wherein the frame comprises a circle.

21. The apparatus of claim 1, wherein the means for capturing an object is substantially dome shaped.

22. The apparatus of claim 1, further comprising a means for receiving an object from the means for capturing an object.

23. The apparatus of claim 1, wherein the plurality of sensor modules have a modular design for easy replacement.

24. The apparatus of claim 1 wherein at least one of the plurality of sensor modules further comprises a motor.

25. The apparatus of claim 1, wherein the controller computes a shape signature produced by an impact on the means for capturing an object to determine trajectory.

26. The apparatus of claim 1 wherein the controller comprises a digital computer.

27. The apparatus of claim 1 wherein at least one of the plurality of sensor modules further comprises a linear displacement transducer.

28. The apparatus of claim 1 wherein at least one of the plurality of sensor modules further comprises an optical encoder.

29. An apparatus for determining position and velocity of an object at impact, comprising:

a) a frame having a plurality of holes and an outer edge;

b) a plurality of sensor modules attached to the outer edge of the frame;

c) a plurality of output drums, wherein at least one of the plurality of output drums is rotatably attached to a sensor module and having an upper spindle, a lower spindle and an axis;

d) a plurality of take up drums, wherein at least one of the plurality of take up drums is attached to the lower spindle by a spring attached at a first end to the lower spindle and having a second end wound around the at least one of the plurality of take up drums, wherein the spring biases the at least one of the plurality of output drums to a rest state;

e) a means for generating a voltage having a shaft, wherein the shaft is attached to the axis of the at least one of the plurality of output drums, and the means for generating a voltage generates a voltage signal proportional to a rate of rotation;

f) means for capturing an object wherein the means for capturing an object is located within the frame and attached to the plurality of output drums by a plurality of cords, wherein each end of each of the plurality of cords passes through one of the plurality of holes and is wound around the at least one output drum; and

g) a controller attached to receive voltage signals from the plurality of sensor units, whereby the controller determines a position and a velocity of impact using the voltage signals.

30. The apparatus of claim 29, wherein a stop attaches to each of the plurality of cords and provides a resting position for the apparatus at a predetermined point.

31. The apparatus of claim 29, further comprising a backing mounted behind the means for capturing an object at a predetermined position to prevent overextension of the plurality of cords.

32. The apparatus of claim 29, further comprising a diode means for damping out a signal generated by the means for generating a voltage during return of the apparatus to resting position.

33. The apparatus of claim 29, wherein the controller determines velocity at impact using a peak voltage value.

34. The apparatus of claim 29, wherein the controller determines velocity at impact using a total voltage value.

35. The apparatus of claim 29, wherein the controller determines a location of impact using a location of a sensor module generating a highest voltage along a predetermined axis.

36. The apparatus of claim 29, wherein the controller determines a location of impact using a location of a pair of sensor modules generating a highest voltage along a predetermined axis.

37. The apparatus of claim 29, wherein the controller computes statistical, graphical and analytical information.

38. The apparatus of claim 29, further including a display unit connected to receive display data from the controller.

39. The apparatus of claim 38, wherein the display unit may display analytical, statistical or graphical information.

40. The apparatus of claim 29, wherein the apparatus returns an object impacting the apparatus to a predetermined location.

41. The apparatus of claim 29 further comprising a second means for capturing an object mounted behind the means for capturing an object.

42. The apparatus of claim 41 wherein the second means for capturing an object provides trajectory information.

43. The apparatus of claim 29 wherein the means for capturing an object comprises a net.

44. The apparatus of claim 43 wherein predetermined strings of the net are attached to one of the plurality of cords.

45. The apparatus of claim 29, wherein the spring comprises a constant force spring.

46. The apparatus of claim 29, wherein the frame comprises a rectangle.

47. The apparatus of claim 46, wherein the plurality of sensor modules are attached to two perpendicular sides of the outer edge of the frame.

48. The apparatus of claim 29, wherein the frame comprises a circle.

49. The apparatus of claim 29, wherein the means for capturing an object is substantially dome shaped.

50. The apparatus of claim 29, further comprising a means for receiving an object from the means for capturing an object.

51. The apparatus of claim 29, wherein the plurality of sensor modules have a modular design for easy replacement.

52. The apparatus of claim 29, wherein the means for generating a voltage comprises a motor.

53. The apparatus of claim 29, wherein the means for generating a voltage comprises an optical encoder for generating a voltage proportional to rotation of the shaft.

54. The apparatus of claim 29, wherein the controller computes a shape signature produced by an impact on the means for capturing an object to determine trajectory.

55. A method for determining position and velocity of impact comprising the steps of:

a) providing a target unit having a net;

b) providing a plurality of sensors disposed along a predetermined set of axis, each of the plurality of sensors extendably attached to the net by a cord;

c) generating a plurality of voltage signals from the plurality of sensors, wherein each one of the plurality of sensors generates a voltage signal proportional to a force directed against a portion of the net attached to a respective one of the plurality of sensors; and

d) determining a velocity and a location from the plurality of sensors.

56. The method of claim 55 further including the step of displaying the velocity and location on a display unit.

57. The method of claim 55 further including the step of providing analytical or statistical information on more than one impact.

58. The method of claim 55 wherein a user may select a mode of operation to choose what analytical or statistical information may be provided.

59. A apparatus for determining position and velocity of an object at impact, comprising:

a) a frame having a plurality of holes and an outer edge;

b) a plurality of sensor modules attached to the outer edge of the frame;

c) a plurality of voltage generators having an axis, wherein one of the plurality of voltage generators is located within each of the plurality of sensor modules, and each of the plurality of voltage generators generates a voltage in proportion to rotation of the axis; and

d) means for capturing an object wherein the means for capturing an object is located within the frame and attached to the plurality of sensor modules by a plurality of cords, wherein each end of each of the plurality of cords passes through one of the plurality of holes and is wound around the axis to cause rotation of the axis when capturing an object.

60. The apparatus of claim 59 further comprising a controller attached to receive voltage signals from the plurality of sensor units, whereby the controller determines a position and a velocity of impact using the voltage signals.

61. The apparatus of claim 60 wherein the controller further comprises a microprocessor.

62. The apparatus of claim 60 further comprising an LED array connected to the controller, wherein the LED array receives a display input from the controller and displays analytical, statistical or graphical information.

63. The apparatus of claim 59 further comprising a plurality of sample and hold circuits each connected to a respective one of the plurality of voltage generators to receive and capture a peak voltage.