Anti Lock Braking System Seminar

8/2/2019 Anti Lock Braking System Seminar

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AJESH R G

S 7 MECHANICAL

7403

MEC


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FUNCTION OF ABS

ABS helps to maintain control and directionalstability of an automobile in case of extreme braking

Supports electronic stability control, brake assist,

traction control


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An ABS system consists of the following components:

Wheel speed sensors

Brake calipers

A hydraulic motor

Pressure release valves

A quick thinking computer which coordinatesthe whole process


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Wheel speed sensor (A), ABS control module (B)

hydraulic motor and pressure release valves (C), Brake pipe leading to caliper (D)


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ABS in detail

The four wheels shown are braking heavily as aresult of heavy brake pedal application, and the green wheel isabout to lock up. . The ABS control module (B) detects theonset of a skid through the sensor (A) in this wheel and reacts

by releasing the brake pressure slightly by rapidly opening apressure release valve (C). This lowers the pressure in thebrake pipe (D) which causes the brake caliper to loosen itsgrip on the brake disc on the locking wheel.A hydraulic motor

(C) will build up the pressure again to the optimum brakingforce and the valve will revert to the closed position.


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Anti-Lock Brake Types

Four-channel, four-sensor ABS

Three-channel, three-sensor ABS

One-channel, one-sensor ABS

There is a speed sensor on all four wheels and aseparate valve for all four wheels

A speed sensor and a valve for each of the frontwheels, with one valve and one sensor for both rear wheels

It has one valve, which controls both rear wheels, andone speed sensor. . In this system it is also possible that one ofthe rear wheels will lock, reducing brake effectiveness.


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Several types of ABS systems

Bosch ABS Actuator (BAA)

Nippon-Denso ABS Actuator (NAA)


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Two yaw motion control systems that

improve a vehicle lateral stability are proposed inthis study: a braking yaw motion controller (BYMC)

and a steering yaw motion controller (SYMC). A BYMC

control the braking pressure of the rear inner

wheel, while a SYMC steers the rear wheels to allow

the yaw rate to track the reference yaw rate. Theperformance of the BYMC and SYMC are evaluated

under various road conditions and driving inputs.

They reduce the slip angle when braking and

steering inputs are applied simultaneously, thereby

increasing the controllability and stability of the

vehicle on slippery roads.

ABSTRACT


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FUNCTIONS OF YAW MOTION CONTROLLER

The main task of a YMC is to limit the slip angle toprevent vehicle spin.

To maintain the slip angle below a characteristic

value to preserve some yaw moment gain


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A yaw motion control device for a vehicle includes a steering

angle sensor for detecting the steering angle of a steering wheel of the vehicle

and a steering angle memory means operatively connected to the steering

angle sensor for storing at least a previous value of the steering angle. A

reference yaw rate generator generates a reference yaw rate in response to aninput from the steering angle memory, and a yaw rate detector detects the yaw

rate of the vehicle. Further, a yaw motion corrector controls the yaw motion of

the vehicle in response to the outputs from the reference yaw rate generator

means and the yaw rate detector. The yaw motion control device set forth

above can also be employed with a vehicle speed detector for detecting thespeed of the vehicle, and for outputting the vehicle speed to said reference yaw

rate generator to provide greater accuracy in controlling the yaw motion of the

vehicle.

YAW MOTION CONTROLLER


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Schematic of BYMC and SYMC

system.


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Effect of road conditions on the yaw motion controller


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Vehicle responses on dry asphalt


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When the BYMC is used, it controls the desired slip of

the rear inner wheel, which is the right rear wheel for this driving

condition. The ABS modifies the brake pressure of the rear inner

wheel to follow the desired slip

The slip of the rear wheels when the BYMC is used


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The steering angle of the rear wheels when the SYMC is

activated

When the SYMC is used, the steering angle of therear wheels is initially opposite to that of the front wheels,

but the direction is changed as the braking maneuverproceeded. The front steering angle is maintained at 5after 2.5 s and the rear steering angle is reduced to zerobecause of the vehicle speed reduction


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ABS, BYMC and SYMC vehicle trajectories on dry asphalt.


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ABS, BYMC and SYMC vehicle trajectories on wet asphalt.


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ABS, BYMC and SYMC vehicleresponses on wet asphalt


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ABS, BYMC and SYMC vehicle trajectories on wet

asphalt.


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ABS, BYMC and SYMC vehicleresponses on snow paved road.


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ABS,BYMCandSYMCvehicletrajectoriesonsnowpavedroad


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Sinusoidal input and vehicle response


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When a sinusoidal input is applied, the steering

control alternates between the left and right rear wheels.

The BYMC controller calculates the desired slip of the rear

inner wheel, while the ABS controls the brake pressure

according to the desired slip. As shown in the bottom left

plot, if the left wheel is on the inside of the turn, its slip

changes from 0.2 to the desired value, while the slip of the

right wheel became 0.2 to reduce the stopping distance.


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Split-l road and vehicleresponse


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The ABS vehicle shows the largest deviationfrom a straight line, while the BYMC and SYMCvehicles have only small deviations. Theseresults demonstrate that the BYMC and SYMCenhance the lateral stability of the vehicle and itssafety on a split-l road.


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Vehicle trajectories on split l road.Vehicle trajectories on split l road.Vehicle trajectories on split l road.Vehicle trajectories on split l road.Vehicle trajectoriesVehicle trajectories on split l road.


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CONCLUSIONS

The first is a braking yaw motion control systemthat controls the braking pressure of the rear inner wheel; theother is a steering yaw motion control system that controls thesteering angle of the rear wheels

When the vehicle is subjected to a braking and corneringmaneuver, the BYMC and SYMC improve its lateral stabilityand controllability, regardless of the road conditions,because they allow the yaw rate of the vehicle to track thereference yaw rate, reducing the slip angle.

When full braking pressure and a sinusoidal steering inputare applied, both the BYMC and SYMC vehicles have reducedslip angles..


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CONCLUSIONS

When full braking input and no steering input are applied toa vehicle on a split ll road, the vehicle travels to the side ofhe road with high friction. However, the BYMC and SYMCreduce the deviation, allowing the vehicle to travel forward.

The SYMC performs better than the BYMC by creating smallerslip angles.


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REFERENCEs

[1]FennelH,DingEL.Amodel-basedfailsafesystemforthecontinentalTEVES

electronic-stability-program(ESP).SAE2000-01-1635;2000.

[2]VanZantenAT.BoschESPsystems:5yearsofexperience.SAE2000-01-1633;

2000.

[3]EsmailzadehE,GoodarziA,VossoughiGR.Optimalyawmomentcontrollaw

forimprovedvehiclehandling.Mechatronics2003;13:65975.

[4]NikzadSV,NaraghiM.Optimizingvehicleresponseinacombinedrideandhandlingfullcarmodelbyoptimalcontrolstrategies.SAE2001-01-1581;

2001.

[5]SongJ,BooK.Performanceevaluationoftractioncontrolsystemsusinga

vehicledynamicmodel.ProcInstMechEngPartD2004;218(7):68596.

[6]SiahkalroudiVN,NaraghiM.Modelreferencetrackingcontrolofa4WSvehicle

usingsingleanddualsteeringstrategies.SAE2002-01-1590;2002.

[7]SongJ.Performanceevaluationofahybridelectricbrakesystemwithasliding

modecontroller.Mechatronics2005;15:33958.


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Anti Lock Braking System Seminar

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