Quarter model of passive suspension system with simscape
• Definition:Suspension system: a mechanical system of springs and shockabsorbers that connect the wheels and axles to the chassis of awheeled vehicle• The Function of suspension system:- to carry the static weight of the vehicle.- to maximize the friction between the tires and the road surface.- to provide steering stability with good handling (minimize bodyroll).- to ensure the comfort of the passengers (ability to smooth out abumpy road).
The Function of Spring: to absorb shock energy from road bump and convert it into potential energy of spring The Function of Shock Absorber: to dissipate shock energy from road bump without causing undue oscillation in the vehicle.
Passive suspension:Traditional springs and dampers are referred to as passive suspensions
Active suspensions:active suspension works by constantly sensing changes in the roadsurface and feeding that information, via the ECU, to the outlyingcomponents. These components then act upon the system to modifyits character, adjusting shock stiffness, spring rate and the like, toimprove ride performance, drivability, responsiveness, etc.
Simscape™ extends Simulink® with tools for modeling and simulating multidomain physical systems, such as those with mechanical, hydraulic, and electrical components. Simscape can be used for a variety of automotive, aerospace,defense, and industrial-equipment applications With Simscape you build a model of a system just as you would assemble a physical system. This approach lets you describe the physical structure of a systemrather than the underlying mathematics.From your model, which closely resembles a schematic, Simscapeautomatically constructs equations that characterize the behavior of thesystem. These equationsare integrated with the rest of the Simulink model.
Problem(1) Forced vibrationEquation Of Motion:f(t)=Kx+Rx+Mx
Model parameters are:Mse-seat and driver mass (90 kg)Ms-is the quarter of the vehicle sprung mass(250kg)Mu-is the quarter of the vehicle unsprung mass(40kg)Bs-Damping ratio of the vehicle suspension(2000Ns/m)Bse-Damping ratio of the seat suspension(3000Ns/m)Kt=Tire stiffness (125000N/m)Ks-vehicle susspension stiffness (28000N/m)Kse-seat suspension spring stiffness (8000N/m)
Equation of motion for drive and seat massis:Equation of motion for sprung mass is: