an overview of vehicle control systems

Vehicle Control SystemsVehicle Control SystemsAn Overview of

Behzad SamadiDepartment of Electrical EngineeringAmirkabir University of Technology

Vehicle Control Systems2

Vehicle Control SystemsVehicle Control Systems ABS TCS ESP 4WS EPS Active Suspension AWD Drive by Wire ANC AEM ACC

S&G ACA OW LW A/F Ratio Control Knock Control Idle Speed Control Variable Compression

Engine VVT ATC CVT


Antilock Braking System (ABS) Antilock Braking System (ABS) 1. Reduce stopping

distance. 2. Maintain

steerability.3. Maintain lateral

stability.


The Operation of ABSThe Operation of ABS Minimize stopping distance. Maximize tire-road adhesion with wheel slip

control.


The Operation of ABSThe Operation of ABS


ABS ComponentsABS Components

Wheel speed sensors.

Electronic control unit.

Hydraulic modulator.


Wheel Speed SensorWheel Speed SensorConstruction Magnetic core with

surrounding coil.

Operation Magnetic field changes

as toothed gear wheel rotates.

AC signal frequency depends on wheel speed.

ECU senses signal and converts it to a square wave.


ABS in Action!ABS in Action!


Traction Control System (TCS)Traction Control System (TCS) Traction control prevents a vehicle's

wheels from spinning excessively while on slippery surfaces.

Traction control is intended as a driver aid which allows a vehicle to make better use of available traction on slippery surfaces.

It shares many of the mechanical and electronic elements of the ABS.


How TCS Works?How TCS Works?Depending on the type of traction control system fitted to the vehicle, wheel spin is controlled by one or a combination of the following: Brake application at one or more wheels. Closing the throttle. Retarding the spark. Fuel cutout. Leaner air/fuel ratio.


TCS in Action!TCS in Action!


Electronic Stability ProgramElectronic Stability Program The electronic stability

program helps improve cornering and control. By monitoring the slip at the wheels as well as the driver's steering and braking inputs, ESP can sense differences between the driver's intentions and the vehicle's direction in turns.


ESP PerformanceESP Performance


ESP OperationESP Operation


ESP ComponentsESP ComponentsA) active wheel speed

sensors

B) steering angle sensor

C) combined yaw rate sensor/lateral accelerometer

D) attached electronic control unit (ECU)

E) motor

F) pressure sensor

G) hydraulic unit


ESP ComponentsESP Components


Automakers & Stability ControlAutomakers & Stability Control Audi: electronic stability program (ESP). BMW: dynamic stability control (DSC). DaimlerChrysler: electronic stability program (ESP). Ford motor company: advance Trac. General motors: active handling system (corvette), precision

control system (Oldsmobile), Stabilitrak (Pontiac, Buick, Cadillac).

Jaguar: dynamic stability control (DSC). Lexus: vehicle skid control (VSC) Porsche: Porsche stability management (PSM). Volkswagen: electronic stability program (ESP). Volvo: dynamic stability traction control (DSTC).


ESP in Action!ESP in Action!


Four Wheel SteerFour Wheel Steer Improve low-speed

maneuverability. Smallest possible

turn radius. Improved handling

at high-speed. Increased vehicle

stability.


Electric Power SteeringElectric Power Steering Reduced engine

drain. Improved fuel

economy and acceleration.

Instant-on power steering.

Added dependability and assist even with engine off.


Active SuspensionActive Suspension Active suspension systems

move each wheel up and down to control body motion in response to road abnormalities.

With an active suspension, a vehicle can simultaneously provide the smooth ride of a soft suspension along with superior handling associated with a firm suspension.


Active Body ControlActive Body Control


Dynamic Body ControlDynamic Body Control


Active Body ControlActive Body Control


Suspension Control in Action!Suspension Control in Action!


All Wheel DriveAll Wheel Drive

When accelerating, weight shifts to the rear, reducing traction in front and AWD direct power to the rear wheels.

When braking, weight shifts forward, reducing traction in back. With AWD, power is instantly directed to the front wheels for better steering control and braking performance.


All Wheel DriveAll Wheel Drive Whether icy, oily, wet, or rough, if front

wheels start to slip, AWD system instantly directs power the rear wheels; If rear wheels start to slip, power is directed to the front wheels.

The power is automatically transferred to the wheels with the best traction. Unwanted understeer and oversteer is virtually eliminated.


Drive by WireDrive by Wire Replacement of traditional mechanical

systems for steering, braking, throttle and suspension functions, with electronic controller, actuators and sensors.


Brake by WireBrake by Wire The braking process is triggered

in the conventional manner by the brake pedal; In the process, the pedal pressure and pedal travel are measured by sensors and converted into electronic signals for the electronic control unit (ECU). The unit that is activated in this way controls the four actuators at the wheel brakes. The brake pads are therefore forced together and opened electromechanically and no longer hydraulically.


Sensotronic Brake ControlSensotronic Brake Control Mechanical components are replaced by electronics. Sensors pass the master cylinder pressure and the

speed with which the brake pedal is operated, to the SBC computer.

To provide the driver with the familiar brake feel, a special simulator is linked to the tandem master cylinder.

Only in the event of a major fault or power failure does SBC instantly establishes a direct hydraulic link between the brake pedal and the front wheel brakes.


Sensotronic Brake ControlSensotronic Brake Control


Steer by WireSteer by Wire Steer-by-wire system

eliminates the mechanical connection between the driver and the vehicle’s front tires. The traditional steering elements are replaced by two actuators positioned in the vehicle’s front corners. These actuators receive input from the control module and turn the front wheels accordingly. The system also uses an electric motor to provide road feedback to the driver’s hand wheel.


Electronic Throttle ControlElectronic Throttle Control Electronic throttle

control (ETC) replaces the throttle cables that run from the accelerator pedal to the engine.


Active Noise ControlActive Noise Control Traditionally noise is

controlled by passive methods: enclosures, barriers and silencers.

Active control is used when passive noise control methods don’t work.

Secondary sources are used to cancel noise from primary source(s) by introducing “antinoise”.


Active Vibration ControlActive Vibration Control

The primary way to cut off paths of noise and vibration from engine is to use soft mounts. However, engine mounts must also constrain or control engine excursions caused by rough roads, firing in cylinders, wheel torque reactions, etc. To limit engine motions, the engine mounts should be stiff and heavily damped. These conflicting requests on engine mounts have prompted automotive industries to search for a new engine mounting method.


Cruise ControlCruise Control The cruise control system controls the

speed of your car the same way you do by adjusting the throttle position.


Adaptive Cruise ControlAdaptive Cruise Control Adaptive cruise control (ACC) improves

on traditional cruise control by allowing a vehicle to automatically adapt to the speed of highway traffic.


Stop and GoStop and Go The Stop & Go function maintains

longitudinal car control at low speeds, e.g. when queuing on a motorway or waiting at a traffic light.


Anti Collision AssistAnti Collision Assist This system helps prevent collisions by sending

the driver an acoustic or visual signal to warn of the presence of standing or slow-moving obstacles in the car's path. The system also acts on the car's brakes when necessary.


Overtaking WarningOvertaking Warning The blind spot coverage sensor warns of the

presence of vehicles about to enter the side area not covered by the door mirrors. The sensor turns on a warning light, which can be used in conjunction with the door mirror. The warning signal becomes acoustic when the turn signal is activated.


Lane WarningLane Warning This additional driving support function

automatically detects car position in relation to lane boundaries. The system issues an advance warning if the car inadvertently crosses the lane boundaries. The road in front of the car is filmed by a micro TV camera and the driver may select between tactile or acoustic indicators.


Engine Control SystemsEngine Control Systems


Air/fuel Ratio ControlAir/fuel Ratio Control A fuel injector is an

electronically controlled valve. It is supplied with pressurized fuel by the fuel-pump in your car.

Two different injection systems:• Manifold injection.• In-cylinder injection.

Lambda: 14.7:1


Effects of Air/fuel RatioEffects of Air/fuel Ratio


Knock ControlKnock Control Self inflammation of the air

fuel mixture.• Increased ambient temperature.• Increased load pressure.• Bad fuel quality.

Usual actuation is a retardation of the ignition angle.

An alternative input: reduce boost pressure of turbo charger.


Idle Speed ControlIdle Speed Control If the idle speed is unstable,

unpleasant vibrations or engine breakdown when started may occur, or fuel economy may drop.

As a rule of thumb, fuel consumption increases proportional to engine speed at idling.

The actuation variable at SI engines is the mass air flow into the engine, at diesel engines the injected fuel amount.


Saab’s Variable Compression Saab’s Variable Compression EngineEngine Improves fuel efficiency by up to 30

percent, reduces tailpipe emissions, and doesn't negatively impact overall performance.

The SVC engine's cylinders are located in the upper section.

By adjusting the "slope" of the upper part of the engine in relation to the lower part by the use of hydraulic actuators, the Saab engine can vary the volume of the combustion chambers. This, in turn, changes the compression ratio.


Variable Valve TimingVariable Valve Timing Valve timing changes with operating

conditions such as engine speed and throttle position.

The engine can rev higher, thus raises peak power. For example, Nissan's 2-liter neo VVL engine output 25% more peak power than its non-VVT version.

Low-speed torque increases, thus improves drivability. For example, fiat Barchetta's 1.8 VVT engine provides 90% peak torque between 2,000 and 6,000 rpm.


Variable Valve TimingVariable Valve Timing


Adaptive Transmission ControlAdaptive Transmission Control ATC adapts transmission shift

parameters according to individual styles of driving (e.g. aggressive vs. relaxed)

Improves shift consistency and transmission durability and allows for shifting that is better suited to specific driver styles or operating conditions


Continuous Variable TransmissionContinuous Variable Transmission

An infinite number of gear ratios to optimize performance and fuel efficiency.

There are no more gear shifts as such, which makes the CVT a highly sophisticated gearbox for high levels of driving comfort.

The metal-link push belt permits high torques of up to 400 nm to be transferred.

The CVT's high gear ratio spread permits the engine to be operated in the low-consumption speed range.


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an overview of vehicle control systems

Automotive

wheel slip control

dynamic stability control

esp operationesp operation

lateral stability

esp componentsesp components

electronic elements

tcs works

wheel spin