Cable tension monitor

1. A sensor apparatus for a movable barrier system including a rotatable drum and an elongate member that winds up on and pays out from an external surface of the rotatable drum, the sensor apparatus comprising:

a sensor including a sensing portion having a first shape wherein the sensing portion is configured to be positioned at the rotatable drum, the sensing portion shapeable to a different, second shape that complements the external surface of the rotatable drum after positioning the sensing portion at the rotatable drum, the sensing portion in the second shape thereof spaced radially from the external surface of the rotatable drum;

the sensing portion configured to sense a first radial distance between the elongate member and the sensing portion with the sensing portion having the second shape; and

a controller operably connected to the sensing portion, the controller configured to detect the elongate member moving radially closer to the sensing portion upon the sensing portion sensing the elongate member at a shorter, second radial distance from the sensing portion without the elongate member contacting the sensing portion,

the controller further configured to effect at least one of a stoppage of the rotatable drum and a reversal of rotational direction of the rotatable drum in response to the controller detecting the elongate member moving radially closer to the sensing portion.

2. The sensor apparatus of claim 1 , wherein the sensing portion is spaced apart from a receiving region of the external surface of the rotatable drum by a distance greater than a diameter of the elongate member.

3. The sensor apparatus of claim 1 ,

wherein the elongate member is between the sensing portion and the external surface of the rotatable drum with the first radial distance between the sensing portion and the elongate member, the elongate member is in contact with the external surface of the rotatable drum, and the elongate member is not in contact with the sensing portion.

4. The sensor apparatus of claim 1 ,

wherein the elongate member is between the sensing portion and the external surface of the rotatable drum with the second radial distance between the sensing portion and the elongate member, the elongate member is not in contact with the external surface of the rotatable drum, and the elongate member is not in contact with the sensing portion.

5. The sensor apparatus of claim 1 , further comprising a signal generator configured to generate a signal in response to the controller detecting the elongate member moving radially closer to the sensing portion.

6. The sensor apparatus of claim 1 , further comprising a signal transmitter configured to transmit a signal in response to the controller detecting the elongate member moving radially closer to the sensing portion.

7. The sensor apparatus of claim 1 , wherein the sensing portion is shapeable by hand.

8. The sensor apparatus of claim 1 , wherein the sensing portion includes a plurality of sensing regions along a central longitudinal axis of the sensing portion, the sensing portion configured to detect the elongate member moving radially closer to at least one sensing portion of the plurality of sensing regions.

9. The sensor apparatus of claim 8 , wherein the plurality of sensing regions comprises a first sensing region and a second sensing region, the first sensing region angularly offset with respect to the second sensing region.

10. The sensor apparatus of claim 1 , further comprising a second sensing portion configured to sense a radial distance between the elongate member and the second sensing portion.

11. The sensor apparatus of claim 10 , wherein the second sensing portion is spaced about an axis of rotation of the rotatable drum from the sensing portion.

12. The sensor apparatus of claim 1 , wherein the sensing portion includes a device selected from the group consisting of a capacitive sensor, an optical interrupter, an inductive sensor, and combinations thereof.

13. A movable barrier system comprising:

a movable barrier operator configured to move a movable barrier in a first direction and a second direction;

an elongate member capable of being connected to the movable barrier;

a rotatable drum rotatable about an axis and having an external surface configured to receive the elongate member thereon, the external surface extending about the rotatable axis and having a predetermined width along the axis;

the elongate member configured to wind up on and pay out from the external surface of the rotatable drum to at least support corresponding movement of the movable barrier; and

a sensor apparatus comprising a sensing portion configured to extend across the external surface of the rotatable drum, the sensing portion configured to sense a first radial distance between the elongate member and the sensing portion at a plurality of sensing regions along a central longitudinal axis of the sensing portion, wherein the sensing portion includes a capacitive sensor, an inductive sensor, or a combination thereof, wherein the sensing portion is shapeable to complement the external surface of the rotatable drum and be radially spaced therefrom; and

a controller connected to the sensing portion, the controller configured to receive information from the sensing portion to detect the elongate member moving radially closer to any of the sensing regions along the width of the external surface of the rotatable drum upon the sensing portion sensing the elongate member at a shorter, second radial distance from the sensing portion, the controller configured to detect the elongate member moving radially closer to the sensing portion without the elongate member contacting the sensing portion,

wherein the controller is further configured to effect, by the movable barrier operator, at least one of a stoppage of rotation of the rotatable drum and a reversal of rotational direction of the rotatable drum in response to the elongate member moving radially closer relative to the sensing portion according to the information received from the sensing portion.

14. The movable barrier system of claim 13 , wherein the movable barrier operator is configured to effect the stoppage of rotation of the rotatable drum to stop movement of the movable barrier in the first direction in response to the elongate member moving radially closer to the sensing portion without the elongate member contacting the sensing portion.

15. The movable barrier system of claim 13 , wherein the movable barrier operator is configured to effect the reversal of rotational direction of the rotatable drum to move the movable barrier in the second direction in response to the elongate member moving radially closer to the sensing portion without the elongate member contacting the sensing portion.

16. The movable barrier system of claim 13 wherein the rotatable drum includes a conical portion having the external surface thereon.

17. The movable barrier system of claim 13 wherein the sensing portion is configured to extend substantially an entire width of the external surface of the rotatable drum.

18. The movable barrier system of claim 13 wherein the sensing portion is configured to have a first shape that permits the sensing portion to be positioned at the rotatable drum, the sensing portion shapeable to a different, second shape that complements the external surface of the rotatable drum.

19. A method comprising:

sensing, by a sensor, a first spaced apart radial proximity of an elongate member connected to a rotatable drum relative to a shapeable sensing portion of the sensor, the shapeable sensing portion having a first shape wherein the shapeable sensing portion is configured to be positioned at the rotatable drum, the shapeable sensing portion shapeable to a different, second shape that complements an external surface of the rotatable drum after positioning the shapeable sensing portion at the rotatable drum, the sensing portion in the second shape spaced radially from the rotatable drum;

sensing, by the sensor, a second spaced apart radial proximity of the elongate member relative to the shapeable sensing portion in the second shape, the second spaced apart radial proximity less than the first spaced apart radial proximity;

in response to sensing the second spaced apart radial proximity less than the first spaced apart radial proximity, determining the elongate member moving radially closer to the shapeable sensing portion of the sensor; and

transmitting a signal to effect at least one of a stoppage of the rotatable drum and a reversal of rotational direction of the rotatable drum in response to determining the elongate member moving radially closer to the shapeable sensing portion.

20. The method of claim 19 further comprising sensing by the sensor a third spaced apart radial proximity of the elongate member relative to a second shapeable sensing portion of the sensor.

21. The method of claim 20 further comprising:

sensing by the sensor a fourth spaced apart radial proximity of the elongate member relative to the second shapeable sensing portion, the fourth spaced apart radial proximity of the elongate member relative to the second shapeable sensing portion different than the third spaced apart radial proximity;

in response to sensing the fourth spaced apart radial proximity different than the second spaced apart radial proximity, determining the elongate member moving radially closer to the second shapeable sensing portion; and

transmitting a second signal to effect at least one of a stoppage of the rotatable drum and the reversal of the rotational direction of the rotatable drum in response to determining the elongate member moving radially closer to the second shapeable sensing portion.

22. The method of claim 19 wherein the shapeable sensing portion complements a cylindrical portion or a frustoconical portion of the rotatable drum including the external surface thereon.