The Door Window Lifting Mechanism Engineering Essay

Mechatronics is at the heart of this boom in vehicle design and functionality. Mechatronics engineering unites the principles of mechanical, electrical, electronics and computing to generate a simpler, more economical, efficient and reliable system.

Applications of Mechatronics in designing products and processes is driving advances in automobiles – the actual cars and components, as well as the equipment needed to build, diagnose and service them. Nowadays the mechatronic systems are reliable, accurate and have a very high efficiency especially in automobiles with Electronic engine controls, Anti-lock braking system and self parking system.

Electronic controlled IC engines without starting motor and driverless car systems are under experiment with the evolution of modern mechatronics.

Door window Lifting Mechanism

http://auto.howstuffworks.com/power-window.htm

In the door window lifting mechanism a small motor is attached to a worm gear and many other spur gears to create a large gear reduction, to reduce speed and to give enough torque to lift the door window.

This mechanism consists of a long linkage arm attached to bottom of window. When the motor turns the gear, that engages the teeth of long linkage arm to move the window up or down depends on motor direction.

Animation of window lifting mechanism at work,

with inset of motor and gear reduction

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Door Lock

Door lock mechanism has to be very reliable because it is going to unlock the doors tens of thousands of times over the life of a car.

http://static.howstuffworks.com/gif/power-lock-intro.jpg

In the power door lock system, the body controller decides to lock or unlock the door. The body controller is nothing but the computer in a car. It monitors for the correct code entered on the door mounted touch pad and unlocks the door. It also monitors the radio frequency signals, when it receives the correct digital code from the radio transmitter in the key fob, it provides power to the actuator that locks or unlocks the door.

Door lock mechanism is quite simple. It consists of a small electric motor that serves as a gear reduction by turning a series of spur gears. The last gear drives a rack and pinion gear set that is connected to the actuator rod. The rotational motion of the motor is converted to linear motion by the rack which is needed to move the lock.

achttp://static.howstuffworks.com/gif/power-lock-actuator2.jpgInside the power-door-lock actuator

A centrifugal switch is connected to the gear and engaged by the motor. When the motor spins the gear, the clutch swings out and locks the small metal gear to the larger plastic gear, allowing the motor to drive the door latch.

http://static.howstuffworks.com/gif/power-lock-gears.jpg

Centrifugal clutch on the drive gear

The body controller also monitors a lot of little things like, it ensures the interior lights stay on until the car is started, it beeps out if

the headlights are left on and also when the keys are left in the ignition condition.

In advanced mechatronics, the switches are connected to one of the many electronic modules in the car. Some cars have one in the driver’s door electronic module, as well as in the body controller. If the driver presses his window switch, the door module closes a relay that provides power to the window motor. If the driver presses the switch to adjust the passenger-side window, the driver’s door module sends a packet of data onto the communication bus of the car. This packet tells the body controller to energize one of the passenger-side window motor.

Wind shield wipers

In windshield wiper mechanism a worm gear is used on the output of a small electric motor since a lot of force is required to accelerate the wiper blades back and forth quickly.

An electronic circuit inside the motor/gear assembly senses when the wipers are in their down position. The circuit maintains power to the wipers until they are parked at the bottom of the windshield.

The new type of wiper system introduced to control the wipes automatically called the Rain sensor system. This system uses the optical sensors to detect the moisture. The sensor projects infrared light into the windshield at a 45-degree angle. If the glass is dry, most of this light is reflected back into the sensor by the front of the windshield. If the glass is wet, the less light makes it back into the sensor.

The electronics and software in the sensor turn on the wipers when the amount of light reflected onto the sensor decreases to a preset level. The system adjusts the speed as often as necessary to match with the rate of moisture accumulation.

Anti-Lock Brakes System

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Anti lock braking system are used to keep the wheels from skidding while slow down and it benefits in two ways: able to stop faster

and also able to steer while it stops.

The controller monitors the speed sensors and looking for decelerations in the wheel that are out of the ordinary. It will experience a rapid deceleration right before wheel locks up.

The ABS controller knows such a rapid decelerations is not possible so it reduces the pressure to that brake until it sees an acceleration, then it increases the pressure until it sees the deceleration again. This process is done very fast before the tyre can actually change speed. The result is that the tire slows down at the same rate as the car giving the system maximum braking power.

Engine Control Unit

computer from a ford ranger

The engine control unit (ECU) is the most powerful computer on most cars. The ECU uses closed-loop control, a control scheme that monitors all the outputs of a system and it controls the inputs to a system, to reduce the emissions and increases the fuel economy of the engine.

Fig Elements of Engine control Unit

ECU gathering the data from sevarl different sensors like speed, temperature, crank shaft position and oxygen in exhaust etc. With this data, it performs millions of calculations in each second, including looking up values in tables, calculating the results of long equations to decide on the best spark timing and determining how long the fuel injection is open. The ECU does all of this to ensure the lowest emissions and best mileage.

A modern ECU might contain a 32-bit, 40-MHz processor, 16 (MB) of memory in an ECU.

Controlling the Cruise Control System

The cruise control system controls the speed by adjusting the throttle position an electronic actuator. The throttle valve controls the power and speed of the engine by limiting air/fuel to the engine.

The brain of a cruise control system is a small computer. It connects to the throttle control, as well as several sensors.

http://static.howstuffworks.com/gif/cruise-control-diagram.gif

A cruise control system accelerates the very fast to the desired speed without overshooting, and then maintains that speed with little deviation at independent of car weight, or how steep the hill you drive up. Controlling the speed of a car is a classic application of control system theory. The cruise control system controls the speed of the car by adjusting the throttle position, by feedback signal from speed and throttle position sensor. Also it needs to monitor the controls so it can tell what the desired speed is and when to disengage.

Adaptive Cruise Control

Adaptive cruise control can automatically control the car speed to maintain a safe following distance. This technique uses forward-looking radar, installed behind the grill of a vehicle, to detect the speed and distance of the vehicle ahead of it.

Adaptive cruise control is same as to conventional cruise control in that it maintains the vehicle’s pre-set speed, but also it need adjust speed in order to maintain a proper distance between vehicles in the same lane. This is achieved through a radar headway sensor, digital signal processor and longitudinal controller. If the lead vehicle slows down, or if another object is detected, the system sends a signal to the engine or braking system to decelerate. Then, when the road is clear, the system will re-accelerate the vehicle back to the set speed.

Self-parking Cars

Some cars have put in rear view cameras, sensors and even computer generated 360-degree views of the car, people still manage to scrape, ding and dent their way into parking spaces.

Self-parking car

The system uses sensors all around the car to guide it into a parallel parking space. The driver has to find a parking space, position the car next to it, and use the in-cabin navigation screen to tell the car where it should go.

Automated Guided Vehicle Systems

FROG ( Free Ranging On Grid) technology is used in Automated Guided Vehicle Systems, which are driverless cars.

FROG

FROG vehicles are equipped with a computer that contains a map of the area in which the vehicle operates. The vehicle starts from a known location and uses the map to determine the route to its destination. It counts wheel revolutions to figure out how far it has travelled (sort of how you might count steps to figure out how far you’ve walked). To check itself, the vehicle also uses various calibration points (electronic landmarks for the vehicle) in the area it works.

Throttle Position Sensor

Throttle Valve

Vacuum Actuator

Cruise Control Computer

Vehicle Speed signal

Brake Pedal Switch

Steering Wheel Controls

Clutch Pedal Switchhttp://static.howstuffworks.com/gif/cruise-control-diagram.gif