Rain Sensing Windshield Wiper Controls
Whether you are driving in rain, snow or your windshield just got soaked by that semi truck that passed you, the Rain Tracker automatically senses the water on the windshield, and activates the wipers at just the right speed. When the weather is clear, the Rain Tracker keeps the wipers off, ready for the next raindrop or snowflake. Your wiper blades last longer, and gone is that annoying "dry wipe smear." Get the convenience and safety of automatic windshield wipers for your car truck or van!
Think of the Rain Tracker as cruise control for your wipers. The Rain Tracker senses water hitting your windshield and runs the wipers at just the right speed. You never have to reach for the knob to adjust for changing conditions. Once you get used to this feature, you will never want to be without it.
The new 2009 RT-50A offers even better rain sensing performance than our previous model RT-50. Further, our new rain sensor is compatible with thick windshields, such as those found on some RV's and heavy trucks, and includes available headlamp control relay output and CAM feedback input.
- Exceptional rain sensing performance. Detects all kinds of precipitation- rain, mist, snow, or sleet.
- Get the same convenient feature found on millions of modern cars.
- One model fits most cars, trucks, and vans. Compatible with over 5000 different vehicles.
- Perfect for original equipment, chassis-builder, RV, or other volume applications.
- Manual wiper control is not affected.
- Full range for operation from off through intermittent, slow, and fast speeds.
- Installs easily -- control module ties into the existing wiper system with just a few wires.
- Tiny rain sensor (1.75"x1.75", 45mmx45mm) on inside surface of windshield.
Remarkable. Better performance at a lower cost.
The Rain Tracker control module works in parallel with the existing wiper system. Manual modes are not affected, which means you don't give up any features. For most installations, the Rain Tracker ties into a few wires coming off the wiper switch. We provide detailed wiring diagrams for over 5000 different vehicles.
A dash-mounted switch activates the Rain Tracker. Simply leave the switch off when it is not raining, or when cleaning the windshield or going through a car wash.
How Rain Tracker Works
All optical rain sensors used in cars and trucks use the same underlying principle. They bounce beams of light through the windshield, and look for disturbances in the beams caused by raindrops. Typically, a rain sensor will have an emitter that emits pulses of light, coupled into the windshield with a lens.
The beams travel through the windshield at about 45°. The beams are infrared thus invisible to humans. The beams are totally internally reflected by the outside surface of the windshield, so they bounce back into the sensor. A detector picks up the beams and measures them.
If rain drops are present on the outside surface of the windshield, some of the beams escape. This reduces the intensity of the beams. The detector senses this, and circuitry measures the reduction in intensity and figures out that it must be raining. The rest of the control system then runs the wipers.
It's Not Really That Simple
That's the idea in theory. To make a real rain sensor that works really well is complicated. The first problem is ambient light from the sun. The sun is hitting the windshield at about a thousand watts of intensity per square meter. The emitters are putting out a few thousandths of a watt. How does the detector know the difference between the light from the emitter and the light from the sun?
To start with, the Rain Tracker picks out only the color of light that is used by the emitters. That is, it uses optical filtering. That's a start (the easy part, actually), but the energy from the sun is broadband, and will have plenty of energy at whatever detector color you choose, including infrared. And to make matters worse, some very smart people at the windshield companies are working diligently to make their products pass as little infrared energy as possible. So, Rain Tracker uses clever circuit techniques that are able to tell the difference between the pulses from the emitter and sharp shadows cast by telephone poles.
Clever optics and clever circuits are still not enough. Sensing sub-millimeter drops in the harsh automotive environment is a truly formidable engineering problem. The Rain Tracker also uses Digital Signal Processing to be able to sense amazingly tiny drops (a fifth of a millimeter in diameter!) even in the presence of strong ambient light. Truly amazing is that the Rain Tracker can sense these drops even when deployed on high performance solar-absorbing glass -- when roughly 1% of the infrared energy makes its way through the round-trip of the windshield.
But it is not enough to just accurately sense rain. Where the system to simply "run the wipers when hit", the control would be subjectively erratic. If the control were to average out the hits over a long period of time, it would appear subjectively sluggish. The Rain Tracker control module uses a patented technique that is designed to mimic human perception, and actuate the wipers just as a driver would. The result is both smooth and responsive.
The Rain Tracker packs an amazing amount of technology into a tiny package. The sensor snaps into a coupler that bonds permanently to the windshield. Field service is greatly simplified: if the windshield should break, the sensor can be put on a new windshield with a new coupler. The simple, one-piece, single material design discourages the formation of air-bubbles.
The Rain Tracker sensor communicates with the vehicle wiper system using a simple three-wire interface, consisting of ground, digital signal, and power.
Rain Tracker RT-50A
Hands-free wipers for almost any vehicle
- Even better rain sensing performance than our previous model RT-50
- Compatible with thick windshields, such as those found on some RV's and heavy trucks
- Light Sensing, Headlamp control output (please see below paragraph)
- Rain-sensing wiper control system controls wipers off through steady high speed in most applications.
- An inconspicuous switch activates or deactivates the system
- The Rain Tracker operates in parallel with the existing wiper system
- Works with the most new digitally controlled (CAN bus) wiper systems
- Proven reliable optical infrared sensing technology
- Unconditionally Guaranteed. Three year warranty.
Headlamp Control Relay Output
Rain Tracker RT-40A
The RT-50A includes a headlamp control relay output that can be used to control the vehicle headlamps. The lights come on when it is raining, or when it is dark. We developed a smart headlamp control algorithm that does and excellent job of turning on the lights just when you would-- a lot like the rain sensor that turns on the wipers just when you would. The lights come on rapidly in a tunnel, yet do not make annoying rapid on/off changes. The performance of our headlamp control system exceeded that of the original-equipment system we benchmarked.
Now the catch: wiring the vehicle for headlamp control is trickier than controlling the wipers. It often involves external relays. So, while we emphasize how straightforward the wiper control wiring is, we make no such claims for the headlamp control. We provide the feature more for the for the professional installer, the OE / Chassis builder applications (e.g. RV's), and the advanced DIY. We advise against its deployment for most non-professionals. We do not offer any technical support or design assistance for the headlamp control feature. The headlamp control works great, but you are on your own to use it.
CAM Feedback Input
Many newer vehicles send digital data from the wiper switch to control the windshield wipers, so you cannot tap into the wiper system coming from the switch. In most of these cases, you can tie into the wiper motor windings at the motor, and use the CAM feedback input of the RT-50A to insure that the wipers properly return home at the end of each cycle.
Same great rain sensing performance through steady slow speed
The RT-40A controls the wipers from off through steady slow -- it will not automatically run the wipers at high speed. There is no headlamp control output. It also does not work with the new digital wiper systems that may need a CAM feedback signal. Use the RT-50A for those applications.
What about car washes?
Turn the Rain Tracker OFF before cleaning the windshield, servicing the wipers, or entering a car wash.
What if a bug hits my windshield?
If you leave your Rain Tracker in rain sensing mode all of the time, once in awhile a bug will hit your windshield right at the sensor. This will trigger the wipers. It can be months between such times. Still, we recommend that drivers leave the Rain Tracker off on dry days, to prevent any unexpected wipes.
Will snow trigger the Rain Tracker?
The Rain Tracker sensor will detect wet snow that sticks to the windshield, and run the wipers appropriately. Cold, dry snow will blow off the windshield without sticking to it. This does not need to be cleared, and will not trigger the sensor.
Will the Rain Tracker automatically run my washer motor?
No. The washer is left under manual control.
What about road spray?
The Rain Tracker will sense road spray, just as it senses a light mist. The sensor does not, however, have any way of knowing how dirty the water is. If you are getting a lot of muddy road spray, you may want to turn the sensitivity down to keep the Rain Tracker from wiping too much and smearing the windshield. With the RT-50A, your intermittent wipers still work, too.
What if my windshield breaks?
The sensor snaps into a coupler that bonds permanently to your windshield. If your windshield should break, you can put the sensor on a new windshield with a new coupler.
Is the Rain Tracker hard to install?
No. An experienced Do-It-Yourselfer or your favorite qualified service technician will find installing the Rain Tracker a straightforward task. See pictures from a typical installation get an idea of what is involved.
This sounds like a great idea. Why aren't rain sensors commonplace?
Actually, they are. About 9% of all new vehicles sold worldwide in 2002 have rain sensing wipers. Shouldn't you be enjoying the safety of hands-free wipers?