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MAK 4045E- Vehicle Dynamics and Control
Assoc. Prof.Dr. Pınar Boyraz
12 May-25 May 2015
Q1. Aerodynamic drag coefficient (Cd) and rolling resistant coefficient (f) of a vehicle will be calculated
using coast-down test. Fort his aim, two different coast down tests have been done in a flat surface. In
first experiment, the vehicle’s speed has been increased to 20m/s, then without any throtlle or brake
command and in neutral gear position the vehicle stops after 40 seconds. In the second experiment
vehicle stops from 30m/s speed in 45 seconds at same conditions. What are the coefficients Cd and f ?
Vehicle Mass (M) : 500kg
Front projection area (A) : 5𝑚2
Air density (𝜌) : 1.2𝑘𝑔/𝑚3
Gravitational acceleration (g) : 9.8𝑚/𝑠 2
Rolling resistant force: 𝑅𝑥 = 𝑓 ∗ 𝑀 ∗ 𝑔
Aerodynamic drag force: 𝐷𝑎 = 0.5 ∗ 𝜌 ∗ 𝐶𝑑 ∗ 𝐴 ∗ 𝑉 2
Q2. a) Sketch a typical time-speed graphic of a vehicle in which ABS (Antilock Braking System) is
activated from 50km/h until it stops.
b) Following speed data is collected from vehicle in every 0.5 seconds. ABS of the vehicle is programmed
to be activated at −2𝑚/𝑠 2 deceleration. According to the data, does ABS activated, if yes when it
happens?
𝑉1 =24.6m/s
𝑉2 =26 m/s
𝑉3 =25.2 m/s
𝑉4 =24.5 m/s
𝑉5 =23.4 m/s
𝑉6 =22.8 m/s
Q3. (a) Explain the reason(s) why driver models are important in developing the vehicles? In what type of
systems is necessary to obtain and use driver model?
(b) Sketch the blockdiagram of the human-driver controlled vehicle system.
Q4. Draw the block-diagram of an Air-to-Fuel Ratio control loop. What does EGR stands for and why do
we have to apply EGR in internal combustion engines?