Sensors and actuators for safer driving in Automotive Industry
What is a sensor?
A Sensor is a device which detect
the presence of energy,
changes in or the transfer of
energy. Sensors detect by
receiving a signal from a device
such as a transducer,
then responding to that signal by
converting it into an
output that can easily be read
and understood.
Typically, sensors convert a
recognized signal into an
electrical – Analog or Digital –
output that is readable.
We can find hundreds of automotive sensors that
measure all sorts of magnitudes.
Some of these may
be: temperatures, engine air flow
intake, distance from an obstacle, motion, etc.
Ø What is an Actuator and what is its purpose in the automotive
industry?
Ø 
Actuators are tasked with supplying a force
to move or “actuate” another mechanical device. The job of actuators is to
convert electrical signals from the control unit into a controlled action. In
short, actuators are the end items that allow for the modification of variables
to be controlled within an automated installation.
Actuators are an essential part of vehicle electro mechanics, and for the most part, they are electric motors and gear motors, or electromagnetic valves that govern,
for example, braking and steering systems.
Various roles of Sensors and actuators in automotive safety:
1. Electronic accelerator
Until
not long ago, information transmission from the accelerator was performed
mechanically, through a steel cable that was connected to the throttle.
Nowadays, vehicles have an electronic throttle control that has a sensor in the
pedal. This element detects the exact position of the pedal at all times and
relays it to the engine control module, which prompts an actuator to change the aperture of the throttle valve.
2. Parking sensor
Parking
sensors are parking assistance devices installed in the vehicle’s bumpers,
especially in the rear ones. These components inform about the obstacles that
may exist in blind spots.
These
parking sensors warn the driver by an acoustic signal when they detect any
obstacle, increasing their intensity to prevent a possible strike.
Different types of parking sensors. There are some main types of parking sensors:
a.
Ultrasound sensors:
Sensors that have a detection field
between 130 and 160 degrees horizontally and between 50 and 60 vertically.
b.
Electromagnetic detection
sensors:
Their own operation is based on the
detection of disturbances in the electromagnetic field produced by solid
objects, being more resistant to possible strikes.
3.
Crankshaft sensor:
The crankshaft sensor, or CKP sensor, sends raw data
to the engine’s computer about its exact position and, since it is connected to
the pistons, the information about its position helps identify the position of
the various critical engine, piston, belt and valve components.
When
operating, the crankshaft sensor uses a metallic disc and a sensor that is
covered by a magnetic coil. The movement of the disk on the coil causes a
magnetic field disturbance, creating electric pulses. Then the engine control
unit uses them to extrapolate the speed and position of the crankshaft.
A crankshaft malfunction mainly
affects the start-up timings and fuel consumption; even though it hinders the
entire engine functionality.
4. Temperature sensors
Also
known as thermistors. Temperature sensors provide
an electric signal depending on the temperature they are subjected to. Since
the introduction of microsystem technologies for the performance of various
passive safety and comfort functions (passenger position for airbag triggering,
air conditioning adjustment depending on body temperature, windshield
defrosting, etc.) contactless temperature sensors are used (pyrometer).
5. Brake assist
The
emergency brake assist (EBA) or brake assist system (BAS) in one of the most
groundbreaking safety devices in current models. These systems are capable of
activating the vehicle’s brakes without any input from the driver. How does
this system work?
The BAS system measures the rate at which the
accelerator pedal is released and activates the brake. On the other hand, it
also collects data regarding the pressure used in the braking system to
interpret if it is an emergency braking.
For its operation, the system has a speed or force sensor located next to the brake pedal, a
valve with an actuator that increases the pressure in the braking circuit, and
a control unit that manages the entire system based on the measurements taken
by the sensor.
Brake
assist systems using radar technology have
also appeared, with the purpose of identifying possible obstacles on the road
and assist the driver in braking in case an unforeseen hazardous situation
emerges.
6. MAF sensor
Also
called air flow sensor or mass flow
sensor. This component electronically measures the amount of air
entering the engine. This information is analysed and automated with the
purpose of controlling the injection system’s air-fuel mix and start-up
adjustment.
The MAF
sensor is located before the engine’s inlet manifold and after the air filter,
and its signal is interpreted in grams per second flow rate. When a greater air
flow enters the engine, RPMs increase, and thus, temperature does as well. The
MAF system has a platinum wire that also measures temperature and relays it to
the control unit. This allows for the detection of engine anomalies and
anticipate possible failures.
7. Sensors and actuators in the electronic fuel injection system
The electronic fuel injection system in a vehicle is
in charge of providing the fuel dosage. An injection
system actuator that can be used to improve this aspect
are: fuel pump relay, purge valve, IAC valve (with actuators that adjust the
air flow and control the revolutions of the engine when idling), etc.
