Abstract:
This thesis aims to see what kinds of performance improvements can be achieved using
an LQR and PID controller on half-car model suspensions for passenger car applica tions. To construct a control system for a half-car model with constant sprung mass,
unsprung mass, damping coefficient, and tire stiffness has been created. Control objec tives including sprung mass acceleration minimization and dynamic tire compression,
as well as suspension travel. Dynamic tire compression is employed as a predictor of
handling quality, whereas the sprung mass acceleration is used to indicate ride com fort.The performances of ASS (with LQR and PID) were evaluated by comparing its
respective passive suspension system (PSS). To investigate the effects of road profiles
and vehicle speeds on ride comfort and road handling performances, two types of road
excitation are designed. These are; random (type B and type C) road inputs and
predictable two bumps sinusoidal road inputs. For the random type B (good surface)
and type C (average), road inputs were designed at four operating vehicle speeds (20
km/hr, 40 km/hr, 60km/hr and 80 km/hr). The simulated MATLAB signal statics of
peak to peak, root mean square (RMS), and settling time are evaluated as parameters
for states of the system. The simulated results of ASS and PSS at selected vehicle
speeds are investigated under selected random road inputs. Two control mechanisms
are used in this dissertation: linear-quadratic optimal (LQR) control and PID control.
Both ride quality for comfort and vehicle handling can be highlighted by developing a
mathematical model for a new design suspension system. With linear quadratic con trol, a 64.577 percent boost in comfort can be achieved on average on the half vehicle
model, according to measurements. This is in contrast to the value of a traditional
suspension system. In addition, the LQR controller improved vehicle handling by 46
percent. As illustrated in the simulation, the comparison of ASS (with PID controller)
is done to their respective PSS for all road inputs and the controlled ASS improves
about 95 percent for sprung masses (ride comfort) in the vertical direction and in the
lateral direction, it contributes a 93.92 percent improvement in the pitching factor, as
well as a 49 percent improvement in for unsprung masses (road handling). From this
research, it can be concluded that the designed LQR and PID controller have excellent
performance for a developed dynamic model, improving the ride quality for passenger
safety and vehicle handling under different road disturbances and vehicle speed opera tions.