Patent Application
20060113936
1. Technical Field
The present invention relates generally to a method and apparatus for retracting an awning, and more particularly to retracting an awning in response to detecting a wind speed persisting over a predetermined time period, or a wind speed exceeding a maximum threshold or a predetermined combination thereof.
2. Background Art
Awnings are used to provide shade from the sun in a variety of settings. Recreational vehicles may have retractable awnings providing a relaxing setting for people when the vehicle is parked, for example. However, excessive weather conditions, such as high wind velocities, can damage such awning if they are not retracted to be protected from the weather conditions. It is to automatically protect such awnings in excessive weather conditions that the present invention has been developed.
One embodiment of the invention takes the form of an apparatus for retracting an awning in response to a wind speed. In the present embodiment, the retraction of the awning occurs under either of two conditions: first, when an average wind speed exceeds a first target value (a “sustained wind speed”) for a predetermined time period; and second, when a wind speed exceeds a second target value (a “peak wind speed”), regardless of the time during which the wind speed exceeds the peak wind speed. It should be noted that an alternative embodiment may require a wind speed to constantly exceed the sustained wind speed during the aforementioned time period to retract the awning. Yet another embodiment may require the wind speed to exceed the sustained wind speed a certain number of times during the time period to retract the awning.
Generally, the present embodiment takes the form of an apparatus attached to an outer edge of an awning. The embodiment typically includes a piezoelectric element, such as a piezoelectric film, which is at least partially exposed to atmosphere. The piezoelectric element is fixed at one end (typically the end opposite that exposed to atmosphere), permitting the element to oscillate as wind blows across the element. A tube or other guide structure may channel wind to the piezoelectric element and also reduce any crosswind.
Acceleration of the piezoelectric element generates an electrical signal. The signal's amplitude varies with the acceleration of the piezoelectric element, as known in the art. That is, the signal measures acceleration of the piezoelectric element, rather than velocity of the element. The signal typically serves as an input to a motor control device. The motor control device may condition the signal (for example, by subjecting the signal to one or more filters, converting the signal from analog to digital, amplifying the signal, and so forth) and actuate the motor when the signal exceeds certain parameters, as discussed above. The motor control device may include a signal conditioning circuit and a microcontroller, among other elements.
The present invention also embraces a method for retracting an awning. The invention generates a first signal corresponding to an awning acceleration, and in response to generating the signal, retracts the awning. Additional features and advantages of the present invention will become apparent upon reading the detailed description, below.
A reversible motor (not shown) is generally also attached to the awning 10, usually within or adjacent to the roll bar 50. The motor operates to extend and retract the awning 10 in a manner known to those skilled in the art by rotating the roll base in one direction or the other.
In alternate embodiments, the casing 100 may be open at one end to permit wind to enter the casing. In such an embodiment, the wind may act directly on the piezoelectric sensor 90, and the open portion of the casing may extend through the housing 80 or roll bar 50.
The piezoelectric sensor 90, shown to best effect in
The piezoelectric sensor 90 is generally electrically connected to a motor controller (not shown). The present embodiment 70 uses a standard telephone cord 130 to connect the sensor 90 to the motor controller, although alternative connections may be used in different embodiments. For example, alternative embodiments might employ a single- or multi-strand conductor terminating in a cable prong, RCA jack, coaxial input, and so forth. Other embodiments may wirelessly couple the sensor 90 and motor controller, for example, by means of a radiofrequency (RF) or infrared transmitter.
The motor controller generally activates and/or deactivates the previously-mentioned motor, which in turn is operative to retract (and, in some embodiments, extend) the awning 10. The motor controller activates the motor in response to an input signal. Parameters for activating the motor are described in more detail below with respect to
In the present embodiment, the signal does not pass from the sensor 90 directly to the motor controller. Instead, the signal is first typically conditioned by a conditioning circuit, and also converted from an analog to a digital signal by a microcontroller. The microcontroller may also perform the duties of the conditioning circuit, such as filtering the input signal. The microcontroller (or a separate circuit) may also amplify the signal or process it in manners not further described herein. The operation of the conditioning circuit and/or microcontroller is discussed in more detail with respect to the flowchart of
Returning to
The present embodiment 70 may be configured to actuate the motor when certain, user-specified, conditions are met. For example, the embodiment may retract an awning 20 only when wind speed (as extrapolated from the force exerted on an awning by the wind, or “wind force”) exceeds a user-chosen constant. The embodiment may include multiple such constants, generally corresponding to “high,” “medium,” and “low” wind speeds. The embodiment 70 may similarly be configured to extend the awning 10 when wind speed drops below the user-chosen constant, or after a certain time has passed.
The user may configure the embodiment 70 and choose from among the various parameters through use of the control panel 140 depicted in
It should be noted, with respect to the present embodiment, the chosen level of acceleration is actually an average acceleration, and must be experienced for a minimum duration before the awning 10 is withdrawn. Thus, references to the acceleration required for retracting an awning 10 are meant to include a time-averaged acceleration. Further, in the present embodiment the averaged acceleration of the awning must exceed the average acceleration chosen by the user for at least two seconds before the awning will retract. Having a minimum duration minimizes the likelihood that the awning may retract accidentally, or when a single gust of wind impacts the awning. Alternate embodiments may have a greater or lesser minimum duration.
Additionally, since the awning 10 may be damaged by a single severe gust, the present embodiment may retract the awning when the awning experiences a sufficiently high acceleration, regardless of the duration of the acceleration. Thus, the present embodiment typically includes a maximum acceleration parameter. When the input signal generated by the sensor 90 exceeds this parameter, even briefly, the awning is retracted. Although the present embodiment does not permit a user to alter the maximum acceleration parameter, alternative embodiments may.
Returning to the discussion of the control panel 140,
As known to those skilled in the art, piezoelectric sensors 90 generally produce an electrical signal varying directly with acceleration of the sensor, rather than with motion (velocity) of the sensor. Thus, the input signal generated by the piezoelectric sensor as the awning 10 and casing 100 move corresponds to the acceleration of the awning, rather than the awning's velocity. Thus, as wind impacts the awning 10, the sensor 90 tracks the acceleration of the awning, not its actual motion. Nonetheless, the awning must move to accelerate; acceleration is the first derivative of velocity. Thus, the piezoelectric sensor's 90 signal may be extrapolated to indicate a motion. For example, converting the amplitude of the input signal generated by the sensor 90 to a frequency would yield a signal whose frequency increases as the awning acceleration increases, and decreases as the awning acceleration decreases. Thus, the frequency of the converted input signal (referred to herein as the “control signal”) is zero when the awning is stationary, and increases with increased motion and acceleration.
The exemplary method of operation begins with operation 600, in which the awning's acceleration due to wind impact is measured. As wind impacts the awning 10, the awning generally shakes up and down, moving in a direction perpendicular to the awning's longitudinal axis. Since the piezoelectric sensor 90 is attached to the awning and is generally coplanar with the awning, the awning's motion is transferred to the sensor. Acceleration of the sensor creates the aforementioned electrical input signal. Thus, the piezoelectric sensor 90 measures the awning's acceleration in operation 600 and creates a corresponding input signal having both a frequency and amplitude. For reference, the frequency of the input signal indicates the duration of the awning's acceleration, while the input signal's amplitude indicates how rapidly the awning 10 accelerates either upward or downward due to the impact of wind thereon. In other words, the input signal's frequency may be thought of as measuring the sustained wind force, while the input signal's amplitude indicates the maximum wind force operating on the awning.
Once the awning's acceleration is measured by the piezoelectric sensor 90 and a corresponding input signal generated, the input signal may be subjected to one or more filters and/or signal processing operations. These signal processing operations are set forth generally as operations 605-615. It should be noted operations 605-615 may occur in different orders than set forth herein.
In operation 605, the input signal is filtered to eliminate peak values of the signal above a certain threshold. Typically, this occurs by subjecting the input signal to a low-pass filter. The low-pass filter clips any portion of the signal above a certain frequency. Thus, high-frequency portions of the input signal/waveform will be filtered out in operation 605.
Since the piezoelectric sensor 90 is cantilevered within the casing 100, which in turn is mounted to the awning 10, the sensor may occasionally experience vibration not experienced by the awning. Given the relative difference between sensor 90 and awning 10 sizes and masses, the sensor may be more sensitive to smaller forces acting on the awning/casing structure than is the awning. Further, if the casing 100 is not securely fastened to the awning, the casing (and enclosed sensor) may sway or “bobble.” Thus, the sensor may generate an input signal falsely indicating the awning is accelerating or moving, when in fact only the sensor is accelerating. Since the awning at least partially braces the casing and sensor, the swing of the sensor is relatively small if the awning does not also move. This typically results in very quick, sharp acceleration and deceleration of the sensor, which in turn creates a high-frequency input signal. Thus, subjecting the signal to a properly-tuned low-pass filter eliminates the relatively high frequencies of the input signal corresponding to motion of the piezoelectric sensor independent from awning motion.
Similarly, the piezoelectric sensor 90 may be subjected to relatively slow, gentle forces that may move the sensor but not the awning 10. As with the more abrupt, relatively weak forces just described, such gentle forces may cause the sensor 90 to falsely register awning motion when, in fact, only the casing 100 and/or sensor moves. This may occur, for example, when gentle gusts of wind act on an improperly- or poorly-mounted casing.
In order to prevent such forces from creating a false positive for the present embodiment 70, inaccurately indicating awning motion that does not occur, the input signal may be further processed. Specifically, the input signal may pass through a high-pass filter in operation 610, which removes low-frequency segments of the input signal that may be generated by the aforementioned gentle forces. Thus, as with the low-pass filter, the high-pass filter may prevent a false positive from being generated by motion of the sensor independent of awning motion.
In operation 615, the input signal may be amplified. In the present embodiment, the input signal is amplified with a gain of 8.0, but alternate embodiments may subject the input signal to amplification with a different gain.
It should also be noted that the input signal may be conditioned to remove direct current (DC) components from the signal. This may be performed, for example, by passing the signal through an appropriately-configured high-pass filter in addition to the high-pass filter discussed with respect to operation 605. Removing DC components from the input signal is entirely optional, but may enhance performance of the embodiment.
The signal may also be converted from an analog signal to a digital signal in operation 620. Generally, the aforementioned microcontroller accepts a digital input, which necessitates this analog-to-digital conversion. Alternative embodiments may employ elements, controllers, and/or circuitry that operate solely with analog inputs. Such embodiments may omit operation 620 without impact.
In operation 625, the input signal is converted by the present embodiment to a control signal. Essentially, the input signal's frequency is converted to an amplitude, typically by the aforementioned microcontroller. Some embodiments may employ an analog or digital frequency-to-amplitude converter, rather than a microcontroller. The conversion from frequency to amplitude is undertaken to ensure compatibility with currently-existing motor controllers. Many motor controllers, for example, are configured to accept an input/control signal from an anemometer. Typically, anemometers measure wind velocity, and output a signal having an amplitude varying directly with wind speed. Thus, converting the frequency of the present embodiment's input signal to an amplitude may permit backwards compatibility. Alternative embodiments may omit such compatibility and perform operations 630-655 based on the frequency of the input signal generated in step 600.
Still with respect to
Generally, the present embodiment retracts the awning 10 under two conditions: first, when the awning experiences sufficiently abrupt motion that the awning may be damaged, regardless of the duration of the motion; and second, when the awning experiences sufficient motion across a set period of time. Operations 635 and 640 in the present flowchart correspond to these two criteria for retracting the awning.
In operation 635, the embodiment determines whether the control signal's frequency exceeds a maximum peak frequency. The peak frequency corresponds to the abrupt motion, and is generally not adjusted by a user via the control panel. If so, the awning is retracted in operation 645.
Otherwise, operation 640 is accessed and the embodiment determines whether the frequency of the control signal exceeds the maximum frequency chosen by the user from the aforementioned control panel. As previously mentioned with respect to
Presuming the control signal exceeds this maximum frequency, the awning is retracted in operation 645. Otherwise, the measuring, sampling, and detection procedure begins again from operation 600.
As discussed above with respect to operation 630, if the awning 10 is retracted operation 650 is accessed. In operation 650, the embodiment (typically via the microcontroller) determines whether the control signal's frequency is below a minimum frequency. If so, the wind speed has dropped below the threshold at which the awning may experience damage, and the awning may be safely extended in operation 655. Otherwise, the monitoring process begins again with operation 600.
It should be noted operations 630, 650, and 655 are entirely optional, and many embodiments may lack such operations. Some embodiments may monitor wind speed/awning acceleration only for the purposes of retracting the awning 10 to prevent damage, and leave extending the awning to the user. Yet other embodiments may employ operations 630, 650, and 655, but only if the embodiment previously retracted the awning. This may prevent the embodiment from abruptly extending the awning 10 when a user would prefer the awning in a retracted state.
Additionally, changing the location of the piezoelectric sensor 90 may prove advantageous in embodiments employing operations 630, 650, and 655. For example, properly weighting the casing 100 and attaching the casing to an independent arm or structure that remains extended even while the awning 20 is retracted may permit the piezoelectric sensor 90 to more accurately measure wind force while the awning 10 is extended, since the sensor would still be exposed to wind even when the awning is withdrawn. Alternately, the embodiment (possibly through operation of the microcontroller) may be configured to further condition the signal to take into account the retraction of the awning and the shielding effect this gives the sensor 90. For example, the control or input signals' gains may be increased further if the casing remains affixed to the awning rail and retracts with the awning, so that minor fluctuations in awning acceleration may be more accurately tracked. This, in turn, may provide more reliable data regarding wind speed and whether the awning may be extended.
Turning now to
The present circuit 230 performs multiple operations on the input signal. The circuit includes an amplifier 240, which amplifies the input signal's amplitude. In one version of the present embodiment, the amplifier has a gain of 8.0, meaning the signal's amplitude after passing through the amplifier is eight times its input amplitude. Alternative embodiments may vary the gain of the amplifier 240. The circuit also includes at least one lowpass filter 250, which prevents portions of the signal above a certain frequency from passing. Similarly, the circuit includes a highpass filter 260, preventing segments of the input filter below a certain cutoff frequency from passing. It should be noted the operations of the lowpass and highpass filters may be combined and replaced by a bandpass filter.
The conditioning circuit also includes an element 270 designed to remove any direct current (DC) waveform from the input signal. Finally, the circuit may include an analog-to-digital converter (not shown) to transform the analog input signal into a digital signal which may, for example, prove advantageous if a microcontroller or other digital processor interacts with the signal. Although the present embodiment subjects the input signal to the highpass filter 260, DC removal filter 270, lowpass filter 250, and amplifier 240, in that order, alternate embodiments may vary the order of circuit elements.
Alternate embodiments of the conditioning circuit 230 may omit one or more of the aforementioned circuit elements. For example, the embodiment 280 shown in
It should be understood the present invention has been described with particular reference to exemplary embodiments and processes. Such embodiments and processes are intended to be exemplary, rather than limiting. Accordingly, the proper scope of the invention is defined by the appended claims.
