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The IRU-2000 model with discrete output, used for presence detection, has two adjustments, sensitivity and trip distance. They are set via single turn potentiometers. A vehicle presents a good reflective target for the sound wave, and the detection distance is less than four feet. These two factors contribute to good detection conditions limiting the required sensitivity to 50%. A high sensitivity level would leave the sensor susceptible to false triggering if high levels of street noise were present.
The second adjustment is the trip distance. This is set to four feet. This distance allows detection of vehicles that do not pull close to the terminal, yet is not set so far away as to detect vehicles that are not pulling into the wash. The trip distance is set by placing a target at the required distance, turning the potentiometer all the way counter clockwise, then slowly turning the potentiometer clockwise until the detection LED turns on. Once the potentiometers are set, the sensor is placed back in the housing preventing tampering and sealing the unit against the elements.
Sensitivity is the only adjustment for the IRU-2000 sensors with analog output. Like the US-25 discrete output sensor above, the adjustment is set to 50 percent. The 4-20mA output is preset at the factory, scaled with 4mA equal to 1 foot and 20mA equal to 10 feet. The wash controller compensates for temperature change by referencing the known distance between the sensors. |
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Ultrasonic proximity sensors provide a new technology solution to the problem of vehicle detection and profile in the latest automatic car washes. The ultrasonic technology solves many problems associated with older photoelectric and inductive ground loop technologies, by its dependability and intelligence.
As a vehicle approaches the car wash terminal, the system must detect the presence of the vehicle. Upon detection, the terminal activates a voice menu for car wash options, providing instruction and prompting the user to upgrade their wash. Automation Products Group, Inc.'s (APG) US-25 sensor is mounted on the terminal stand providing non-contact detection of vehicles regardless of color or shape.
Inside the wash, the vehicle width and length must be determined in order to maximize the wash performance. In a touchless wash, the spray nozzles have an optimum range where they provide the most effective cleaning. US-25 sensors are mounted on the carriage that supports the wash wand. As the carriage travels the length of the wash bay the sensors measure the distance to the vehicle. This provides the wash controller with both the left/right position of the vehicle as well as its width and length.
APG's IRU-2000 ultrasonic sensors are ideal for this application. There are no floor mounted mechanical devices to install and maintain. There are no lenses to become dirty as with photoelectric sensors, and they are environmentally sealed to withstand the conditions inside the wash.
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| Mounting for Car Wash Applications |
The ideal elevation for mounting the IRU-2000 sensor is 24 inches above the pavement. Through testing, an elevation of 24 inches has proven to be the most reliable for detection of all makes and models of vehicles. The minimum detection range of the sensor is 12 inches. The sensor must be located so a vehicle cannot come closer than this distance or the vehicle may not be detected.
The sensor must be mounted so that it is perpendicular to the vehicle. If the vehicle is aligned at an angle to the sensor the sound will be reflected away, causing the sensor to indicate no vehicle is present. Acceptable alignment is between zero and five degrees off perpendicular.
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