The document discusses various chassis control systems including anti-lock braking systems (ABS), traction control systems (TCS), electronic stability programs (ESP), and advanced driver assistance systems (ADAS). ABS uses sensors and a controller to prevent wheel lockup during heavy braking. TCS activates during acceleration to prevent wheel slip. ESP improves stability by detecting and reducing loss of traction, applying brakes independently to wheels as needed.

1. Chassis Control Systems:
ABS-Antilock Braking system:Anti-lock braking systems (ABS) are active
safety features designed to help drivers retain steering control by preventing
wheels from locking up during an episode of heavy braking
Sensor inputs:
 Wheel speed sensor
 Vehicle speed sensor
 Brake lever position sensor
Controller unit.
Calculated slip on the basis of the formula
Eeshan Bashir
Mtech ARAI ACADEMY
푠푙푖푝 =
푣 − 휔푟
푣
Hence, for a locked wheel 휔푟 =0 is described by slip =1, while 휔푟 = 푣 denotes the
free motion of the wheel.
휔 r= denote the wheel speed.
However The Braking dynamics of vehicle needs to be considered while designing an
actual Antilock brake model
The parameters that affect ABS system are:
 Drive torque
 Wheel Mass
 Gravity(g)
 Wheel radius
 Moment of inertia
 Braking torque
Notes:
 No wheel lock allowed to occur for speeds above 4 m/s
 wheel lock for a period of less than 0.2 seconds is allowed for speeds in the
range of 0.8 . . .4 m/s
 for speeds below 0.8 m/s the wheels are allowed to lock

Traction control system: is typically a secondary function of the anti-lock
braking system. TCS is activated when throttle input and engine torque are
mismatched to road surface conditions causing wheel slip, designed to prevent
loss of traction of driven road wheels.
Intervention consists of one or more of the following:
 Brake force applied to one or more wheels
 Reduction or suppression of spark sequence to one or more cylinders
 Reduction of fuel supply to one or more cylinders
 Closing the throttle, if the vehicle is fitted with drive by wire throttle
 In turbocharger vehicles, a boost control solenoid is actuated to reduce
boost and therefore engine power.
Calculation of Slip in traction system.
Calculated slip on the basis of the formula

2. Eeshan Bashir
Mtech ARAI ACADEMY
푠푙푖푝 =
휔푟 − 푣
휔푟
Hence, for a Spinning wheel 휔푟 > 푣 is described by slip =1, while 휔푟 = 푣 denotes the
Full adhesion no slipping of wheel.
휔 r= denote the wheel speed.
푣= vehicle speed.
However The Braking dynamics of vehicle needs to be considered while designing an
actual Antilock brake model /Traction Control model.
general inputs and outputs for ABS/TCS 1
Electronic Stability Program:
This is a active safety technology that improves the stability of the vehicle by
detecting and reducing loss of the traction, brakes are applied when Electronic
stability program detects a loss of steering control. The loss of the steering
control can be due to Under-steering or Over-steering during cornering. The
ESP ECU controls against over-steering or under-steering during cornering by
controlling the vehicle stability using the input values from the sensors and
applying the brakes independently to the corresponding wheels. The system
also limits the engine output by limiting the throttle.
Sensor Inputs:
 Steering wheel angle sensor
 Yaw rare sensor
 Lateral acceleration sensor

3.  Wheel speed sensor
 Longitudinal acceleration sensor
Control system Diagram
These equations are used to calculate the desired values for vehicle side slip
and vehicle and vehicle yaw velocity.
Desired yaw rate:
With
Wheel toe angle due to steering wheel angle.
Maximum desired yaw rate
Eeshan Bashir
Mtech ARAI ACADEMY

4. Desired vehicle side slip angle
With
푙 푟 distance CoG to rear axle
푙푓distance CoG to front axle
l wheel base
ρ=v/ ψ inverse corner radius
퐶훼2 cornering stiffness rear axle.
Empirical relation to determine maximum vehicle side slip angle
With
μ푠 frictional coefficient tyres to road
g gravitational acceleration.
These formulations are desired for calculation of error vector which serves as
an input for controller
ESP during Under steering:
Eeshan Bashir
Mtech ARAI ACADEMY

5. Under steering is when the steering wheel is steered to a certain angle during
the front tires slip towards the reverse direction of the desired direction. The
ESP system recognizes the directional angle with the steering wheel angle
sensor and the slipping route that occurs reversely against the vehicle
cornering direction during under-steering with the yaw rate sensor and the
lateral sensor. Then the ESP system applies the brake at the rear inner wheel
to compensate the yaw moment value.
ESP during Over steering:
Oversteering is when the wheel is steered to a certain angle during driving and
the rear tires slip outward losing traction. ESP system recognizes the
directional angle with the steering angle sensor and senses the slipping route
that occurs towards the vehicle cornering direction during over steering with
the yaw rate sensor and the lateral sensor. Then the ESP brakes at the front
outer wheel to compensate the yaw moment value.
Some other Chassis control systems include:
Advanced Driver Assistance Systems (ADAS)
Electronic chassis control (suspension, steering, damping etc.)
Eeshan Bashir
Mtech ARAI ACADEMY