1. Field of the Invention
The present invention relates to the field of automatic gates. More specifically, the invention relates to methods and devices for controlling the operation of moveable barriers. The invention relates to apparatus for detecting objects or obstructions in the pathways of moveable barriers.
2. Background Art
Moveable barrier operators are automated systems which are utilized to move a barrier or gate between a fully open position and a fully closed position. Some examples of moveable barriers are sliding gates, swing gates, barrier arms and overhead doors. A typical moveable barrier operator consists of a motor coupled to a drive train attached to the moveable barrier to move the barrier between fully open and fully closed positions.
Such powered moveable barrier operators are controlled by various inputs to carry out an open, close or stop command. Inputs usually consist of wired contact switches, wireless receiver units along with their respective transmitters or a combination of both.
Obstructions may exist or enter the pathway of the moveable barrier. Previous systems have incorporated obstruction detection to allow the moveable barrier operator to sense when an object or obstruction has been encountered and to stop or reverse the direction of movement once the moveable barrier operator has determined that an object or obstruction has been encountered. Such systems typically detect obstructions by measuring barrier speed, measuring motor current or monitoring a safety switch input from an external contact detection device such as a Miller edge strip or an external non-contact device such as a photoelectric beam. Other prior art systems have used capacitive sensors or loop detectors as obstruction detectors.
A Miller edge strip relies on physical contact with the sensor. The photoelectric beam, though a non-contact system, has a limited field of detection. Safety loop systems are widely used, but they only detect vehicles. They cannot detect non-ferrous objects such as humans, pets or composite bicycles. Previous capacitive sensor systems use a reference member or sensing member coupled such that the reference member is maintained at a fixed distance from the sensing element. All of the prior art systems mentioned above have serious limitations as to their efficiency and overall safety. By way of example, contact sensors or photoelectric beams could result in inadvertent injury or damage despite the attempt to avoid such results.
A system and method for the determination of an object or obstruction in the pathway of a moveable barrier should also avoid false detection of objects or obstructions. In the preferred embodiment hereof an array of sensor elements is positioned on the edge of a moveable barrier and the output of each sensor element is measured. A sensor circuit coupled to the sensor elements determines whether an object or obstruction is in the pathway of the moveable barrier by comparing the relative measurements of the sensor elements. This system and method is relatively inexpensive and can be implemented on conventional movable barrier systems.
In one embodiment of the invention, an array of sensors is positioned on the leading edge of a moveable barrier. The output of each sensor is measured and the reading of each sensor is compared to the readings of the other sensors. If one or more sensor readings are substantially different than the rest of the readings, it can be inferred that an obstruction or object exists in the pathway of the moveable barrier. If all of the measured sensor readings are substantially similar, it can be determined that there is no object or obstruction in the pathway of the moveable barrier even as the moveable barrier approaches its endpoint where a pillar or fence post may exist. If it is determined that an object or obstruction exists in the pathway of the moveable barrier, the sensor controller can then signal the moveable barrier controller to either stop or reverse the direction of the moveable barrier prior to coming in contact with the obstruction or object in the pathway of the moveable barrier.
The moveable barrier may be any type of moveable barrier, including for example, a barrier arm, an overhead door, a swing gate, or a sliding gate.
Thus, in the present invention, a system and method are provided where a measurement made by each sensor of a plurality of sensors is compared to the other sensors to determine if an object or obstruction exists in the pathway of a moveable barrier. A substantially different reading from one or more sensors is an indication of an object or obstruction in the pathway of the moveable barrier. However a substantially similar reading from all sensors is indicative of the absence of an object or obstruction in the pathway of the moveable barrier.
The aforementioned objects and advantages of the present invention, as well as additional objects and advantages thereof, will be more fully understood herein after as a result of a detailed description of a preferred embodiment when taken in conjunction with the following drawings in which:
Those skilled in the art will appreciate that the elements in the figures are illustrated for simplicity and clarity and are not necessarily drawn to scale.
For illustrative purposes, the following description refers to a moveable barrier that is a swing gate. However, it will be understood by those skilled in the art that the moveable barrier can be any type of barrier such as a sliding gate or a barrier arm or any other type of moveable barrier.
Referring now to
The swing gate 12 has a sensor array system 22 mounted to the leading edge of the swing gate. The sensor array system 22 can be mounted to the swing gate to form either a vertical array 24 or a horizontal array 26 to provide the best object or obstruction detection according to the individual swing gate system installation.
Examples of a sliding gate is shown in
Referring now to
The sensor array 34 detects changes in capacitance and is read by controller 32. If the detected changes occur such that on object or obstruction in the pathway of the swing gate is detected, the controller 32 signals the swing gate operator either through the connecting wires or alternatively through the wireless transceiver. The swing gate operator may then stop or reverse the direction of the swing gate.
In the preferred embodiment of the present invention, a plurality of sensors form a distributed array which monitor the entire length of the gate. The gate is enabled if and only if all of the sensors detect the same status. If all of the sensors “see” a target, it is assumed that they have detected a fixed non-interfering target structure such as a wall or tree in the distance that would not constitute an obstruction to movement of the gate. Of course, if all of the sensors do not sense a target, there is no obstruction that could interfere with the gate. On the other hand, if only one or more of the sensors “sees” a target, but not all of them, then it is more likely to be an actual obstruction such as a car or a person.
While there has been illustrated and described a particular embodiment of the present invention, it will be appreciated that changes and modifications will occur to those skilled in the art and that such changes and modifications may be made to the illustrated embodiments without departing from the spirit of the present invention.