Smart Sensors in Late Model Cars
Clusters are now used on a smaller scale for smart sensors. For instance, a typical pressure sensor has a component that sends out varying voltage, depending on the pressure placed on it. Typically, the voltage output is not constant, it can vary with the temperature, and it is a low-level voltage, which means it needs amplification.
Some manufacturers are creating a smart sensors, which is integrated with all the electronics. A microprocessor allows it to read the voltage, calibrates it with temperature-curves, and digitally outputs the pressure onto the communications bus. In this way, the car manufacture doesn’t have to worry about all the intricate details of the sensor and the supplier is just responsible for designing a smart sensors that can provide an accurate reading.
Another benefit of the smart sensor is that the digital signal moving over the communications bus is less vulnerable to electrical noise. An analog voltage traveling through a wire can gather additional voltage as it passes electrical components or even from distant power lines above.
Through multiplexing, communication buses and microprocessors help simplify the wiring. Let’s look into how this works.
Multiplexing is a technique that simplifies the wiring in a vehicle. In older cars, a wire for each switch ran to the device it powered. With so many devices being put into vehicles each year, multiplexing is essential to keep the wiring from going, well, haywire.
In a multiplexed system, a module with at least one microprocessor combines the inputs and outputs for a section of the car. For instance, driver-side doors with a lot of window and lock switches will have a driver-door module. Some cars have electronically powered windows, mirrors, locks, and even seats. It would be dangerous to stick a thick mass of wires like this into the door. Instead, the module keeps track of all the switches.
So, if the driver pushes the window switch, the module closes a relay that provides energy to the motorized window. If the driver pushes the switch to adjust the passenger-side mirror, the door module fires a packet of data onto the communication bus. This packet causes a different module to power one of the mirror motors. This is how the majority of the signals that are sent out from the driver’s door are consolidated in the two wires, forming the communication bus.
Safety, Comfort and Convenience In the last decade, safety systems like ABS and air bags have become more common on cars. Other safety features, like traction- and stability-control systems, are becoming common, too. Each of these additional systems adds another new module to the car. In a few more years, there will be more and more modules as newer safety systems are built into future vehicles.
Each new safety systems demands more processing power, which is usually in its own electronics module. And it doesn’t stop there. In coming years, we can all expect more convenience features to be added in each new generation of cars, and each will need more electronics modules with even more micro-processing ability.
No one can say what the limit will be and just how much technology car manufacturers will be able to fit into our cars. With all these new electronic features, carmakers will have to increase the system voltage from the present-day 14-volt to a 42-volt system. Hopefully, this will be enough to power all the electronic modules and their hundreds of microprocessors in the future age of driving.
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