Sensor fusion of acceleration sensor and air pressure sensor information to estimate elevator floor level and position

A method of monitoring a conveyance apparatus within a conveyance system including: detecting a first atmospheric air pressure within the conveyance system proximate the conveyance apparatus; detecting a second atmospheric air pressure within the conveyance system proximate the conveyance apparatus; determining a change in atmospheric air pressure proximate the conveyance apparatus in response to the first atmospheric air pressure and the second atmospheric air pressure within the conveyance system; and determining at least one of a location of the conveyance apparatus and a direction of motion of the conveyance apparatus within the conveyance system in response to at least the first atmospheric air pressure and the second atmospheric air pressure.

BACKGROUND

The embodiments herein relate to the field of conveyance systems, and specifically to a method and apparatus for monitoring a position of a conveyance apparatus of a conveyance system.

A position of a conveyance apparatus within a conveyance systems, such as, for example, elevator systems, escalator systems, and moving walkways is often difficult to determine.

BRIEF SUMMARY

According to an embodiment, a method of monitoring a conveyance apparatus within a conveyance system is provided. The method including: detecting a first atmospheric air pressure within the conveyance system proximate the conveyance apparatus; detecting a second atmospheric air pressure within the conveyance system proximate the conveyance apparatus; determining a change in atmospheric air pressure proximate the conveyance apparatus in response to the first atmospheric air pressure and the second atmospheric air pressure within the conveyance system; and determining at least one of a location of the conveyance apparatus and a direction of motion of the conveyance apparatus within the conveyance system in response to at least the first atmospheric air pressure and the second atmospheric air pressure.

In addition to one or more of the features described herein, or as an alternative, further embodiments may include: detecting an acceleration in response to the change in atmospheric air pressure proximate the conveyance apparatus.

In addition to one or more of the features described herein, or as an alternative, further embodiments may include that prior to determining the method further includes: detecting local weather conditions; and adjusting the first atmospheric air pressure and the second atmospheric air pressure in response to the local weather conditions.

In addition to one or more of the features described herein, or as an alternative, further embodiments may include that confirming that conveyance apparatus is in motion in response to the acceleration.

In addition to one or more of the features described herein, or as an alternative, further embodiments may include that the acceleration of the conveyance apparatus is movement of the conveyance apparatus in a direction about parallel to a direction of travel of the conveyance apparatus.

In addition to one or more of the features described herein, or as an alternative, further embodiments may include that the acceleration is detected in a direction about perpendicular to a direction of travel of the conveyance apparatus.

In addition to one or more of the features described herein, or as an alternative, further embodiments may include that the conveyance system is an elevator system and the conveyance apparatus is an elevator car.

According a sensing apparatus for monitoring a conveyance apparatus within a conveyance system is provided. The sensing apparatus including: a processor; and a memory including computer-executable instructions that, when executed by the processor, cause the processor to perform operations, the operations including: detecting a first atmospheric air pressure within the conveyance system proximate the conveyance apparatus; detecting a second atmospheric air pressure within the conveyance system proximate the conveyance apparatus; determining a change in atmospheric air pressure proximate the conveyance apparatus in response to the first atmospheric air pressure and the second atmospheric air pressure within the conveyance system; and determining at least one of a location of the conveyance apparatus and a direction of motion of the conveyance apparatus within the conveyance system in response to at least the first atmospheric air pressure and the second atmospheric air pressure.

In addition to one or more of the features described herein, or as an alternative, further embodiments may include that the operations further include: detecting an acceleration in response to the change in atmospheric air pressure proximate the conveyance apparatus.

In addition to one or more of the features described herein, or as an alternative, further embodiments may include that prior to determining the operations further includes: detecting local weather conditions; and adjusting the first atmospheric air pressure and the second atmospheric air pressure in response to the local weather conditions.

In addition to one or more of the features described herein, or as an alternative, further embodiments may include that the operations further include: confirming that conveyance apparatus is in motion in response to the acceleration.

In addition to one or more of the features described herein, or as an alternative, further embodiments may include that the acceleration of the conveyance apparatus is movement of the conveyance apparatus in a direction about parallel to a direction of travel of the conveyance apparatus.

In addition to one or more of the features described herein, or as an alternative, further embodiments may include that the acceleration is detected in a direction about perpendicular to a direction of travel of the conveyance apparatus.

In addition to one or more of the features described herein, or as an alternative, further embodiments may include that the conveyance system is an elevator system and the conveyance apparatus is an elevator car.

According to another embodiment, a computer program product tangibly embodied on a computer readable medium is provided. The computer program product including instructions that, when executed by a processor, cause the processor to perform operations including: detecting a first atmospheric air pressure within the conveyance system proximate the conveyance apparatus; detecting a second atmospheric air pressure within the conveyance system proximate the conveyance apparatus; determining a change in atmospheric air pressure proximate the conveyance apparatus in response to the first atmospheric air pressure and the second atmospheric air pressure within the conveyance system; and determining at least one of a location of the conveyance apparatus and a direction of motion of the conveyance apparatus within the conveyance system in response to at least the first atmospheric air pressure and the second atmospheric air pressure.

In addition to one or more of the features described herein, or as an alternative, further embodiments may include that the operations further include: detecting an acceleration in response to the change in atmospheric air pressure proximate the conveyance apparatus.

In addition to one or more of the features described herein, or as an alternative, further embodiments may include that prior to determining the operations further includes: detecting local weather conditions; and adjusting the first atmospheric air pressure and the second atmospheric air pressure in response to the local weather conditions.

In addition to one or more of the features described herein, or as an alternative, further embodiments may include that the operations further include: confirming that conveyance apparatus is in motion in response to the acceleration.

In addition to one or more of the features described herein, or as an alternative, further embodiments may include that the acceleration of the conveyance apparatus is movement of the conveyance apparatus in a direction about parallel to a direction of travel of the conveyance apparatus.

In addition to one or more of the features described herein, or as an alternative, further embodiments may include that the acceleration is detected in a direction about perpendicular to a direction of travel of the conveyance apparatus.

Technical effects of embodiments of the present disclosure include determining a location and/or direction of motion of a conveyance apparatus within a conveyance system in response to the atmospheric pressure within the conveyance system.

DETAILED DESCRIPTION

Conveyance systems, such as, for example, elevator systems, escalator systems, and moving walkways may require periodic monitoring to perform diagnostics using a variety of sensors. The sensors may be one way sensing apparatus that only communicate data rather than receiving data, thus saving power. Such sensing apparatus may require a location/position of the conveyance system to supplement detected data and must detect the location of the conveyance system by itself and embodiments disclosed herein seek to address this issue.

The tension member107engages the machine111, which is part of an overhead structure of the elevator system101. The machine111is configured to control movement between the elevator car103and the counterweight105. The position reference system113may be mounted on a fixed part at the top of the elevator shaft117, such as on a support or guide rail, and may be configured to provide position signals related to a position of the elevator car103within the elevator shaft117. In other embodiments, the position reference system113may be directly mounted to a moving component of the machine111, or may be located in other positions and/or configurations as known in the art. The position reference system113can be any device or mechanism for monitoring a position of an elevator car and/or counter weight, as known in the art. For example, without limitation, the position reference system113can be an encoder, sensor, or other system and can include velocity sensing, absolute position sensing, etc., as will be appreciated by those of skill in the art.

The controller115is located, as shown, in a controller room121of the elevator shaft117and is configured to control the operation of the elevator system101, and particularly the elevator car103. For example, the controller115may provide drive signals to the machine111to control the acceleration, deceleration, leveling, stopping, etc. of the elevator car103. The controller115may also be configured to receive position signals from the position reference system113or any other desired position reference device. When moving up or down within the elevator shaft117along guide rail109, the elevator car103may stop at one or more landings125as controlled by the controller115. Although shown in a controller room121, those of skill in the art will appreciate that the controller115can be located and/or configured in other locations or positions within the elevator system101. In one embodiment, the controller may be located remotely or in the cloud.

The machine111may include a motor or similar driving mechanism. In accordance with embodiments of the disclosure, the machine111is configured to include an electrically driven motor. The power supply for the motor may be any power source, including a power grid, which, in combination with other components, is supplied to the motor. The machine111may include a traction sheave that imparts force to tension member107to move the elevator car103within elevator shaft117.

Although shown and described with a roping system including tension member107, elevator systems that employ other methods and mechanisms of moving an elevator car within an elevator shaft may employ embodiments of the present disclosure. For example, embodiments may be employed in ropeless elevator systems using a linear motor to impart motion to an elevator car. Embodiments may also be employed in ropeless elevator systems using a hydraulic lift to impart motion to an elevator car.FIG. 1is merely a non-limiting example presented for illustrative and explanatory purposes.

In other embodiments, the system comprises a conveyance system that moves passengers between floors and/or along a single floor. Such conveyance systems may include escalators, people movers, etc. Accordingly, embodiments described herein are not limited to elevator systems, such as that shown inFIG. 1. In one example, embodiments disclosed herein may be applicable conveyance systems such as an elevator system101and a conveyance apparatus of the conveyance system such as an elevator car103of the elevator system101. In another example, embodiments disclosed herein may be applicable conveyance systems such as an escalator system and a conveyance apparatus of the conveyance system such as a moving stair of the escalator system.

Referring now toFIG. 2, with continued referenced toFIG. 1, a view of a sensor system200including a sensing apparatus210is illustrated, according to an embodiment of the present disclosure. The sensing apparatus210is configured to detect sensor data202of the elevator car103and transmit the sensor data202to a remote device280. Sensor data202may include but is not limited to pressure data314, vibratory signatures (i.e., vibrations over a period of time) or accelerations312and derivatives or integrals of accelerations312of the elevator car103, such as, for example, distance, velocity, jerk, jounce, snap . . . etc. Sensor data202may also include light, sound, humidity, and temperature, or any other desired data parameter. The pressure data314may include atmospheric air pressure within the elevator shaft117. It should be appreciated that, although particular systems are separately defined in the schematic block diagrams, each or any of the systems may be otherwise combined or separated via hardware and/or software. For example, the sensing apparatus210may be a single sensor or may be multiple separate sensors that are interconnected.

In an embodiment, the sensing apparatus210is configured to transmit sensor data202that is raw and unprocessed to the controller115of the elevator system101for processing. In another embodiment, the sensing apparatus210is configured to process the sensor data202prior to transmitting the sensor data202to the controller115. In another embodiment, the sensing apparatus210is configured to transmit sensor data202that is raw and unprocessed to a remote system280for processing. In yet another embodiment, the sensing apparatus210is configured to process the sensor data202prior to transmitting the sensor data202to the remote device280.

The processing of the sensor data202may reveal data, such as, for example, a number of elevator door openings/closings, elevator door time, vibrations, vibratory signatures, a number of elevator rides, elevator ride performance, elevator flight time, probable car position (e.g. elevation, floor number), releveling events, rollbacks, elevator car103x, y acceleration at a position: (i.e., rail topology), elevator car103x, y vibration signatures at a position: (i.e., rail topology), door performance at a landing number, nudging event, vandalism events, emergency stops, etc.

The remote device280may be a computing device, such as, for example, a desktop or cloud computer. The remote device280may also be a mobile computing device that is typically carried by a person, such as, for example a smartphone, PDA, smartwatch, tablet, laptop, etc. The remote device280may also be two separate devices that are synced together, such as, for example, a cellular phone and a desktop computer synced over an internet connection. The remote device280may also be a cloud computing network.

The sensing apparatus210is configured to transmit the sensor data202to the controller115or the remote device280via short-range wireless protocols203and/or long-range wireless protocols204. Short-range wireless protocols203may include but are not limited to Bluetooth, Wi-Fi, HaLow (801.11ah), zWave, Zigbee, or Wireless M-Bus. Using short-range wireless protocols203, the sensing apparatus210is configured to transmit the sensor data202to directly to the controller115or to a local gateway device240and the local gateway device240is configured to transmit the sensor data202to the remote device280through a network250or to the controller115. The network250may be a computing network, such as, for example, a cloud computing network, cellular network, or any other computing network known to one of skill in the art. Using long-range wireless protocols204, the sensing apparatus210is configured to transmit the sensor data202to the remote device280through a network250. Long-range wireless protocols204may include but are not limited to cellular, satellite, LTE (NB-IoT, CAT M1), LoRa, Satellite, Ingenu, or SigFox.

The sensing apparatus210may be configured to detect sensor data202including acceleration in any number of directions. In an embodiment, the sensing apparatus may detect sensor data202including accelerations312along three axis, an X axis, a Y axis, and a Z axis, as show in inFIG. 2. The X axis may be perpendicular to the doors104of the elevator car103, as shown inFIG. 2. The Y axis may be parallel to the doors104of the elevator car103, as shown inFIG. 2. The Z axis may be aligned vertically parallel with the elevator shaft117and pull of gravity, as shown inFIG. 2. Vibratory signatures may be generated along the X-axis and the Y-axis as the elevator car103moves along the Z-axis.

FIG. 3shows a possible installation location of the sensing apparatus210within the elevator system101. The sensing apparatus210may include a magnet (not show) to removably attach to the elevator car103. In the illustrated embodiment shown inFIG. 3, the sensing apparatus210may be installed on the door hanger104aand/or the door104of the elevator system101. It is understood that the sensing apparatus210may also be installed in other locations other than the door hanger104aand the door104of the elevator system101. It is also understood that multiple sensing apparatus210are illustrated inFIG. 3to show various locations of the sensing apparatus210and the embodiments disclosed herein may include one or more sensing apparatus210. In another embodiment, the sensing apparatus210may be attached to a door header104eof a door104of the elevator car103. In another embodiment, the sensing apparatus210may be located on a door header104eproximate a top portion104fof the elevator car103. In another embodiment, the sensing apparatus210is installed elsewhere on the elevator car103, such as, for example, directly on the door104.

As shown inFIG. 3, the sensing apparatus201may be located on the elevator car103in the selected areas106, as shown inFIG. 3. The doors104are operably connected to the door header104ethrough a door hanger104alocated proximate a top portion104bof the door104. The door hanger104aincludes guide wheels104cthat allow the door104to slide open and close along a guide rail104don the door header104e. Advantageously, the door hanger104ais an easy to access area to attach the sensing apparatus210because the door hanger104ais accessible when the elevator car103is at landing125and the elevator door104is open. Thus, installation of the sensing apparatus210is possible without taking special measures to take control over the elevator car103. For example, the additional safety of an emergency door stop to hold the elevator door104open is not necessary as door104opening at landing125is a normal operation mode. The door hanger104aalso provides ample clearance for the sensing apparatus210during operation of the elevator car103, such as, for example, door104opening and closing. Due to the mounting location of the sensing apparatus210on the door hanger104a, the sensing apparatus210may detect open and close motions (i.e., acceleration) of the door104of the elevator car103and a door at the landing125. Additionally mounting the sensing apparatus210on the hanger104aallows for recording of a ride quality of the elevator car103.

FIG. 4illustrates a block diagram of the sensing apparatus210of the sensing system ofFIGS. 2 and 3. It should be appreciated that, although particular systems are separately defined in the schematic block diagram ofFIG. 4, each or any of the systems may be otherwise combined or separated via hardware and/or software. As shown inFIG. 4, the sensing apparatus210may include a controller212, a plurality of sensors217in communication with the controller212, a communication module220in communication with the controller212, and a power source222electrically connected to the controller212.

The plurality of sensors217includes an inertial measurement unit (IMU) sensor218configured to detect sensor data202including accelerations312of the sensing apparatus210and the elevator car103when the sensing apparatus210is attached to the elevator car103. The IMU sensor218may be a sensor, such as, for example, an accelerometer, a gyroscope, or a similar sensor known to one of skill in the art. The accelerations312detected by the IMU sensor218may include accelerations312as well as derivatives or integrals of accelerations, such as, for example, velocity, jerk, jounce, snap . . . etc. The IMU sensor218is in communication with the controller212of the sensing apparatus210.

The plurality of sensors217includes a pressure sensor228is configured to detect sensor data202including pressure data314, such as, for example, atmospheric air pressure within the elevator shaft117. The pressure sensor228may be a pressure altimeter or barometric altimeter in two non-limiting examples. The pressure sensor228is in communication with the controller212.

The plurality of sensors217may also include additional sensors including but not limited to a light sensor226, a pressure sensor228, a microphone230, a humidity sensor232, and a temperature sensor234. The light sensor226is configured to detect sensor data202including light exposure. The light sensor226is in communication with the controller212. The microphone230is configured to detect sensor data202including audible sound and sound levels. The microphone230is in communication with the controller212. The humidity sensor232is configured to detect sensor data202including humidity levels. The humidity sensor232is in communication with the controller212. The temperature sensor234is configured to detect sensor data202including temperature levels. The temperature sensor234is in communication with the controller212.

The controller212of the sensing apparatus210includes a processor214and an associated memory216comprising computer-executable instructions that, when executed by the processor214, cause the processor214to perform various operations, such as, for example, processing the sensor data202collected by the IMU sensor218, the light sensor226, the pressure sensor228, the microphone230, the humidity sensor232, and the temperature sensor234. In an embodiment, the controller212may process the accelerations312and/or the pressure data314in order to determine a probable location of the elevator car103, discussed further below. The processor214may be but is not limited to a single-processor or multi-processor system of any of a wide array of possible architectures, including field programmable gate array (FPGA), central processing unit (CPU), application specific integrated circuits (ASIC), digital signal processor (DSP) or graphics processing unit (GPU) hardware arranged homogenously or heterogeneously. The memory216may be a storage device, such as, for example, a random access memory (RAM), read only memory (ROM), or other electronic, optical, magnetic or any other computer readable medium.

The power source222of the sensing apparatus210is configured to store and supply electrical power to the sensing apparatus210. The power source222may include an energy storage system, such as, for example, a battery system, capacitor, or other energy storage system known to one of skill in the art. The power source222may also generate electrical power for the sensing apparatus210. The power source222may also include an energy generation or electricity harvesting system, such as, for example synchronous generator, induction generator, or other type of electrical generator known to one of skill in the art.

The sensing apparatus210includes a communication module220configured to allow the controller212of the sensing apparatus210to communicate with the remote device280or controller115through at least one of short-range wireless protocols203and long-range wireless protocols204. The communication module220may be configured to communicate with the remote device280using short-range wireless protocols203, such as, for example, Bluetooth, Wi-Fi, HaLow (801.11ah), Wireless M-Bus, zWave, Zigbee, or other short-range wireless protocol known to one of skill in the art. Using short-range wireless protocols203, the communication module220is configured to transmit the sensor data202to a local gateway device240and the local gateway device240is configured to transmit the sensor data to a remote device280through a network250, as described above. The communication module220may be configured to communicate with the remote device280using long-range wireless protocols204, such as for example, cellular, LTE (NB-IoT, CAT M1), LoRa, Ingenu, SigFox, Satellite, or other long-range wireless protocol known to one of skill in the art. Using long-range wireless protocols204, the communication module220is configured to transmit the sensor data202to a remote device280through a network250. In an embodiment, the short-range wireless protocol203is sub GHz Wireless M-Bus. In another embodiment, the long-range wireless protocol is Sigfox. In another embodiment, the long-range wireless protocol is LTE NB-IoT or CAT M1 with 2G fallback.

The sensing apparatus210includes a location determination module330configured to determine a location (i.e., position) of the elevator car103within the elevator shaft117. The location of the elevator car103may be fixed locations along the elevator shaft117, such as for example, the landings125of the elevator shaft117. The locations may be equidistantly spaced apart along the elevator shaft117or intermittently spaced apart along the elevator shaft117.

The location determination module330may utilize various approaches to determine a location of the elevator car103within the elevator shaft117. The location determination module330may be configured to determine a location of the elevator car103within the elevator shaft117using at least one of a pressure location determination module310and an acceleration location determination module320.

The acceleration location determination module320is configured to determine a distance traveled of the elevator car103within the elevator shaft117in response to the acceleration of the elevator car103detected along the Y axis. The sensing apparatus210may detect an acceleration along the Y axis shown at322and may integrate the acceleration to get a velocity of the elevator car103at324. At326, the sensing apparatus210may also integrate the velocity of the elevator car103to determine a distance traveled by the elevator car103within the elevator shaft117during the acceleration312detected at322. The direction of travel of the elevator car103may also be determined in response to the acceleration312detected. The location determination module330may then determine the location of the elevator car103within the elevator shaft117in response to a probable starting location and a distance traveled away from that probable starting location. The probable starting location may be based upon tracking the past operation and/or movement of the elevator car103.

The pressure location determination module310is configured to detect an atmospheric air pressure within the elevator shaft117when the elevator car103is in motion and/or stationary using the pressure sensor228. The pressure detected by the pressure sensor228may be associated with a location (e.g., height, elevation) within the elevator shaft117through either a look up table or a calculation of altitude using the barometric pressure change in two non-limiting embodiments. The direction of travel of the elevator car103may also be determined in response to the change in pressure detected via the pressure data314. The pressure sensor228may need to periodically detect a baseline pressure to account for changes in atmospheric pressure due to local weather conditions. For example, this baseline pressure may need to be detected daily, hourly, or weekly in non-limiting embodiments. The acceleration is elevator car103may also need to be detected to know when the elevator car103is stationary and when the elevator car103is stationary the sensing apparatus210may need to be offset to compensate the sensor drift and environment drift.

In one embodiment, the pressure location determination module310may be used to verify and/or modify a location of the elevator car102within the elevator shaft117determined by the acceleration location determination module320. In another embodiment, the acceleration location determination module320may be used to verify and/or modify a location of the elevator car102within the elevator shaft117determined by the pressure location determination module310. In another embodiment, the pressure location determination module310may be prompted to determine a location of the elevator car103within the elevator shaft117in response to an acceleration detected by the IMU sensor218.

Referring now toFIG. 5, while referencing components ofFIGS. 1-4.FIG. 5shows a flow chart of a method500of monitoring a location of a conveyance apparatus within a conveyance system, in accordance with an embodiment of the disclosure. In an embodiment, the conveyance system is an elevator system101and the conveyance apparatus is an elevator car103.

At block504, a first atmospheric air pressure is detected within the conveyance system proximate the conveyance apparatus. At block506, a second atmospheric air pressure is detected within the conveyance system proximate the conveyance apparatus. As discussed above, the atmospheric air pressure (e.g., the first atmospheric air pressure and the second atmospheric air pressure) may be detected by the pressure sensor228may be associated with a location (e.g., height) within the elevator shaft117through either a look up table or a calculation of altitude using the barometric pressure change in two non-limiting embodiments. In another embodiment, the pressure sensor228may need to periodically detect a baseline pressure to account for changes in atmospheric pressure due to local weather conditions or sensor drift. For example, this baseline pressure may need to be detected daily, hourly, or weekly in non-limiting embodiments.

At block508, a change in atmospheric air pressure proximate the conveyance apparatus is determined in response to the first atmospheric air pressure and the second atmospheric air pressure within the conveyance system.

At block510, at least one of a location of the conveyance apparatus and a direction of motion of the conveyance apparatus within the conveyance system is determined in response to at least the first atmospheric air pressure and the second atmospheric air pressure.

The method500may also include that an acceleration is detected in response to the change in atmospheric air pressure proximate the conveyance apparatus. The detected acceleration may be used to determine that the elevator car103is in motion. In one embodiment, the atmospheric air pressure (e.g., the first atmospheric air pressure and the second atmospheric air pressure) may be detected prior to detecting the acceleration of the conveyance apparatus and then the acceleration of the conveyance apparatus may be detected in response to the change in atmospheric pressure. In another embodiment, the acceleration may be detected first and then the atmospheric air pressure (e.g., the first atmospheric air pressure and the second atmospheric air pressure) may be detected in response to the detection of an acceleration.

The acceleration of the conveyance apparatus may be movement of the conveyance apparatus in a direction about parallel to a direction of travel of the conveyance apparatus. For example, the acceleration of the conveyance apparatus may be that the elevator car103is moving through the elevator shaft117. The acceleration is detected in a direction about perpendicular to a direction of travel of the conveyance apparatus. In another embodiment, the acceleration detected may be an acceleration of the conveyance apparatus away from a stationary position. For example, the acceleration of the conveyance apparatus may be that the elevator car103is accelerating from a velocity of zero to a velocity greater than zero. In another embodiment, the acceleration detected is a deceleration of the conveyance apparatus to a stationary position. For example, the acceleration of the conveyance apparatus may be that the elevator car103is decelerating from a velocity greater than to a velocity of zero. In another embodiment, the acceleration detected in is a movement of a door104of the elevator car103. Advantageously, by only detecting the atmospheric air pressure when an acceleration is detected then the atmospheric air pressure is not being detected continuously, which conserves electrical energy of the sensing apparatus210.

The method500may further include that prior to determining the method further comprises: detecting local weather conditions; and adjusting the first atmospheric air pressure and the second atmospheric air pressure in response to the local weather conditions.

While the above description has described the flow process ofFIG. 5in a particular order, it should be appreciated that unless otherwise specifically required in the attached claims that the ordering of the steps may be varied.

The term “about” is intended to include the degree of error associated with measurement of the particular quantity and/or manufacturing tolerances based upon the equipment available at the time of filing the application.